Design of High Voltage Power Supply System for Application of Electrohydrodynamic Drying

Design of High Voltage Power Supply System for Application of Electrohydrodynamic Drying | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Design of High Voltage Power Supply System for Application of Electrohydrodynamic Drying Anas Ejaz Yasmeen Shaikh, Hari Niwas Mishra This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5591834/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Electrohydrodynamic (EHD) drying is an emerging technique for energy-efficient, non-thermal, and high-quality drying of food and biomaterials. It is based on enhancement of moisture removal from food material under action of electric wind resulting from corona discharge, which is generated when high voltage is applied across two electrodes with different radii of curvature. A high voltage power supply (HVPS) is an important component in experimental set-up for studying EHD drying process. In the present study, an HVPS for EHD drying of food has been developed based on its design, measurement, and control requirements. A flyback or line output transformer was used to generate high voltage up to range of 10 kV (peak-to-peak output voltage). Performance of HVPS was evaluated using current-voltage characteristics and power consumption. Maximum peak-to-peak output current obtained was ~ 450 mA under load of 20 MΩ. Average and root mean-squared power of HVPS ranged from 9 to 26 W and 13 to 35 W, respectively. Cost and weight of HVPS were 5,588 INR and 2.4 kg, respectively. Thus, the designed HVPS offered low-cost and portable solution to generate high voltage for electrohydrodynamic drying. This research will expedite the process for development of electrohydrodynamic dryers for food industry. Physical sciences/Engineering/Chemical engineering Physical sciences/Engineering/Electrical and electronic engineering Health sciences/Health care/Nutrition Electrohydrodynamic drying Food High Voltage Power Supply Design Fabrication Performance evaluation Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction In the past decade, there has been an increasing trend in the application of electrohydrodynamic (EHD) processing to food and biomaterials 1 . Depending on whether the application is for solid or liquid products, EHD processing can serve different purposes. In case of liquid food products, EHD processing can be used for electrospraying and electrospinning 2 . Electrospraying has been used to produce dried powders from liquid food matrices such as egg 3 as well to encapsulate valuable food ingredients such as essential oils 4 , saffron extract 5 , β-carotene 6 , and curcumin 7 . On the other hand, electrospinning can be used to produce nanofibers from viscous polymeric solutions such as those of hydrocolloids like starch 8 and pullulan 9 , and plant proteins like zein 10 , soy and gelatin 11 , and pea 12 . These nanofibers not only find applications in food packaging but also can be used as delivery systems for nutraceuticals, such as probiotics 13 through encapsulation. On the other hand, for solid food products, EHD processing has been used to dry food and biomaterials. The EHD drying technique has been applied for drying of solid food products such as slices of ginger 14 , potato 15 , apple 16 , banana slices, mushroom 17 , and shrimps 18 . The technique of EHD processing is based on the application of a high voltage across two electrodes with different radii of curvature. The non-uniform electric field generated between the two electrodes leads to corona discharge and the generation of an electric wind 19 . In EHD processing of liquid food products, the Taylor’s cone formation leads to the atomization of the liquid followed by spraying or spinning due to the electric wind 20 . The major components of an EHD set-up for processing of liquid foods include a high voltage power supply, syringe pump, syringe needle as emitter electrode and collector electrode. On the other hand, in EHD processing of solid foods, seven mass transfer mechanisms were identified by Iranshahi et al. (2022) and the convective effect due to electric wind was reported as a major mechanism for the drying of solid food products. The major components of an EHD set-up for processing of solid foods include a high voltage power supply, emitter and collector electrodes. For researchers in the field of food and bioprocessing, one of the hurdles to build a concise set-up for experiments on EHD processing is in the incorporation of high voltage power supply (HVPS) in the set-up. The EHD processing of food and biomaterials requires high voltages but very low currents. Some of the available HVPS commercial units that have been used in studies on EHD drying of food materials, along with their specifications for comparison have been mentioned in Table S1 . The HVPS systems that have been in the studies are bulky as they are manufactured to meet high current requirements and and even if they are made for meeting the requirements of lower currents, they are expensive (Table S1 ) . Furthermore, the use of a commercially available HVPS gives little opportunity to a researcher to conduct an in-depth analysis of the HVPS in such a way that it’s design can be tuned to meet the scale for different applications. A study was conducted on the design and simulation of an adjustable HVPS for electrospinner application, however, this study was only based on simulation without fabricating the power supply and the maximum voltage generated was too high 22 . Thus, there is a need to develop a low-cost and portable HVPS system that is particularly designed for EHD applications. There is a dearth of studies on the development of HVPS systems for EHD applications. Thus, the design of an HVPS can give the mainstream life science researchers an opportunity to understand the electrical system in a more mechanistic way rather than the black box approach involved in the use of commercially available high voltage power supplies. In this study, a low-cost and portable HVPS system has been designed, fabricated, and tested, to EHD drying process. Given its easy and widespread availability, flyback or line output transformer has been incorporated for generation of high voltage in the HVPS system. This study lays a foundation for the design of HVPS systems for EHD drying of solid foods and can prove to be a useful tool in the design and development of EHD dryers in the future. 2. Materials and Methods 2.1 Materials All electronic components including construction materials for fabrication used in this study have been listed in Table S2 and were procured from local shops or online purchase. 2.2 Circuit for HVPS In this section, the design, measurement, and control requirements of the electrical circuit for the HVPS have been described. 2.2.1 Design requirement The voltage requirements for EHD drying was set as 0 to 10 kV. The high voltage generation was achieved primarily through the flyback transformer (FBT) or line output transformer (LOPT) (Fig. 1 ). The required output DC high voltage from the FBT and thereby from the HVPS system ( V hvps ) was adjusted using two input controls, namely input pulsating DC voltage supplied to the FBT ( V in ) and switching frequency of pulse width modulator ( f SW ). The magnitude of V in was determined by the uppermost part of the circuit shown by the schematic in Fig. 1 by construction of a DC-bus comprising of step-down transformer T1, bridge rectifier BR1, capacitor filter C1, bleeder resistor R1 and LED1 for indicating discharging followed by potentiometer Pot1 for controlling the output of transistor Q1. On the other hand, the frequency and duty ratio of this pulsating DC input voltage Vin to the FBT was controlled using pulse width modulator NE555 and transistor Q2 along with diode D3 served as switch for transforming the output at emitter of Q1 to pulsating DC to be fed as input to the FBT. The ripples in the PWM output were minimized by capacitor C8. The lower part of the circuit shown in the schematic in Fig. 1 consisted of a second DC-bus made up of center-tapped step-down transformer T2, full wave rectifier made using diodes D1 and D2, and capacitor filter C2. This circuit was followed by linear voltage regulators U2 (LM7809), and U3 and U4 (LM78L12 each) for obtaining regulated output voltages of 9 V, and 12 V, respectively, to power auxiliary devices of the HVPS. A DC fan powered at 12 V using LM78L12 was used for removal of heat generated in the circuit and heat sinks were attached to the transistors Q1 and Q2 (each BU536) and bridge rectifier block for heat dissipation. The 12 V voltage generated using voltage regulator LM78L12 was also used for powering the digital voltmeter at the front panel of the HVPS (Fig. 3 d) as well as for PWM while the 9 V generated using voltage regulator LM7809 was used to power the digital oscilloscope DSO138 which is also at the front panel of the HVPS (Fig. 3 d). Similar to the DC-bus in upper part of the circuit, bleeder resistor R2 and LED2 for indicating discharging were provided. The PWM was assembled in astable mode using standard assembly comprising of resistor R3, potentiometer POT2, and capacitors C6 and C7. The output current from the HVPS ( I hvps ) was limited in the desired range using a resistance voltage divider comprising of twenty resistors of 1 MΩ each attached at the output of the FBT. The design requirements for circuit protection were met by using a fuse of 2 A at input. Moreover, separate switches, Sw1 and Sw2, were provided for mains and high voltage, respectively (Fig. 1 ). Furthermore, an RC circuit (Fig. 1 ) comprising of parallel combination of capacitor (10 nF; 1 kV) and resistance (1.5 kΩ) was used as a snubber across the transistor Q2 for protecting it against high voltage spikes (Fig. 1 ). The specifications of all the electronic components as well as other construction materials used in the design and fabrication of the HVPS have been summarized in Table S2. 2.2.2 Measurement requirement The primary measurement requirements for the HVPS system include those for the output high voltage ( V hvps ) and current ( I hvps ). The high voltage generated in the HVPS was a result of the input voltage to the flyback transformer ( V in ) and the output parameters of the of the pulse width modulator, namely duty ratio ( D PWM ) and switching frequency ( f sw ). The average value of the input voltage to the flyback transformer ( V in,avg ) was displayed by the digital voltmeter attached at the front panel of the HVPS (Fig. 3 d) while the waveform for V in was captured using 50:1 differential probe of oscilloscope (DLM3024, Yokogawa, Japan) (Fig. 4 a) at the front panel of the HVPS system. On the other hand, the output of the pulse width modulator was monitored using the digital oscilloscope (DSO138, JYE Tech) which was incorporated as a part of the HVPS system. Thus, the values for the duty ratio ( D PWM ) and switching frequency ( f sw ) were procured from the DSO138 reading (Fig. 3 d). For this two probing points were provided at the front side of the HVPS system from which the DSO138 probes were connected (Fig. 3 d). The DSO was powered at 9 V using voltage regulator, LM7809 (Fig. 1 ). For given values of V in , D PWM or f SW , the output high voltage ( V hvps ) values were measured using voltage divider comprising of 20 arms of resistors each with value of 1 MΩ (Fig. 4 b). The output voltage across one arm closest to the ground terminal of the HVPS was recorded using a 100:1 probe (Multicomp PRO MP770217) in the oscilloscope (DLM3024, Yokogawa, Japan) (Fig. 4 a). Based on these parameters, calibration charts mapping the input parameters ( V in and f SW ) to the output parameter ( V hvps ) was prepared (Fig. 3 f and Fig. 3 g). The calibration chart can be used to obtain V in and f SW to get the desired output high voltage from the HVPS. For measurement of current through the primary winding of FBT ( I in ) and output current from the HVPS system ( I hvps ), a Techtronix differential current probe set at 0.1A/V was used for recording in the Yokogawa oscillosope (Fig. 4 a). Since the currents I hvps and I in are very small, the measurements through the current probes were performed through seven- and six-turn windings, respectively (Fig. 4 b), thus these responses recorded through the oscilloscope represent seven- and six-times magnified currents, respectively (Fig. 6 a). The experiments for measuring and recording waveforms of V in , V hvps , I in , and I hvps under different settings of V in and f SW consisted of one set of experiments. On the other hand, the measurement of input power required by the HVPS system through the mains ( P mains ) under different settings of V in and f SW comprised of another set of experiments. The details for measurement of P mains have been provided in section 2.4.2. These voltage measurements were performed at sixteen points shown in Fig. 1 . The HVPS offered only two probe points at its front panel (shown in Fig. 3 d) corresponding to ‘P14’ and ground as shown in Fig. 1 . The additional probes for the other fifteen points of measurement were obtained through the components assembled (Fig. 3 b) on the PCB (Fig. 3 (a)) by opening the enclosure. 2.2.3 Control requirement The output voltage from the flyback transformer ( V hvps ) was controlled using the analog regulators provided at the front panel of the system (Fig. 3 d). One of the regulators (Pot1 in Fig. 1 ) was used to control the input voltage to the flyback ( V in ) while the other one (Pot2 in Fig. 1 ) was used to control duty ratio ( D PWM ) and switching frequency ( f SW ) of the pulse width modulator in the astable mode. These regulators have also been depicted in Fig. 3 d. Moreover, as a safety measure, a switch (Sw2 in Fig. 1 ) for input voltage to the flyback transformer ( V in ) was provided at the back panel of the system (Fig. 3 e) in addition to the mains switch (Sw1 in Fig. 1 ) provided at the front panel of the system (Fig. 3 d). 2.3 Fabrication of HVPS The electrical circuit designed and simulated was subsequently fabricated to develop the high voltage power supply. 2.3.1 Hardware description The main external hardware element of the high voltage power supply consisted of the output high voltage and ground terminals to be connected to the emitter and collector electrodes, respectively. These terminals were designed to be at the back panel of the system (Fig. 3 e). The terminals were connected to the electrodes using alligator cables, which are accessories with the HVPS system. Besides, the mains supply cable for AC ( V rms_mains = 230 V; f mains = 50 Hz), high voltage switch, and fuse box were among other external hardware elements that were provided at the back panel of the HVPS. On the other hand, the mains switch, regulators for potentiometers, oscilloscope along with its buttons and power cable, voltage probes after the pulse width modulator, and digital voltmeter were among other external hardware elements that consisted of the front panel of the HVPS system (Fig. 3 d). The enclosure for the HVPS has been designed in such a way that it can be easily opened for diagnostic purposes with the two LED’s provided in the circuit serving as preliminary diagnostic tools. The internal hardware consisted of the circuit assembly based on the designed circuit (Fig. 1 ) and the elements used have been listed in Table S2. The details about the electronic hardware have been specified in section 2.2.1. 2.3.2 Enclosure for HVPS The enclosure for the HVPS was made using transparent acrylic sheet of thicknesses 2.79 mm and 1.93 mm to ensure insulation for the high voltage circuit. The enclosure was designed to make the system compact (size: 124 mm × 263 mm × 85 mm) and light in weight (2.397 kg). The enclosure also consisted of compartment for housing the digital oscilloscope. The enclosure was also designed to incorporate suitable sections for cables of mains supply and of DSO power supply. It also provided sections for high voltage and ground terminals. Furthermore, the enclosure was provided with clearance at the bottom using four acrylic stands. The enclosure was colored using metallic silver spray paint (Rust Oleum 1915830). The dimensions of the enclosure have been provided in the engineering drawing (Fig. 3 c) constructed using Solidworks 2022 software. 2.3.3 Bill of materials The bill of materials for the electronic components and other building materials, such as acrylic sheet and color, used in the fabrication of the high voltage power supply system has been provided in Table S2. The acrylic sheet of thickness 2.79 mm was used to fabricate the bottom support of the enclosure to provide mechanical strength for holding the electrical circuit while the acrylic sheet of thickness 1.93 mm was used to fabricate the top cover of the enclosure as its cost was lower than the former sheet. The cost of raw material for manufacturing one unit of the power supply was estimated using it. 2.3.4 Build instructions Based on the designed circuit, the printed circuit board (PCB) was designed and fabricated on a 2 mm general purpose board by etching (Fig. 3 a). The electronic components were then assembled on the board (Fig. 3 b). The enclosure was prepared separately with the sections cut out for the external hardware elements described in section 2.3.1. The enclosure was colored on its outside surface with metallic silver spray paint. The assembled PCB was fitted into the enclosure and the external hardware were installed in the cut sections and connected to appropriate positions on the PCB. After the installation, the enclosure top cover was attached to complete the build-up of the high voltage power supply. 2.3.5 Voltage calibration Voltage calibration was performed to find out the value of high voltage output ( V hv ) for set values of the two inputs to the FBT, namely, input voltage ( V in ) and switching frequency of the pulse width modulator ( f sw ). The peak-to-peak voltage ( V hv,pp ) was used as indicator of the high voltage output. The output high voltage was monitored using Yokogawa across one arm of the resistance voltage divider. Calibration charts depicting the high voltage response, V hvps for different values of V in and f sw were generated to determine the high voltage output for the corresponding input settings. 2.3.6 Operation instructions The overall operation of the HVPS for electrohydrodynamic drying can be divided into three phases, namely, OFF-phase, partial-ON-phase, and ON-phase. The OFF phase is when none of the two switches are ON and consists primarily of connecting all the accessories. To complete this phase, firstly the high voltage and ground probes provided at the back panel need to be connected using cables, respectively, to the emitter and collector electrodes of the electrohydrodynamic drying experimental setup. This is followed by connecting DSO138 to the appropriate probe points provided at the front panel as shown in Fig. 3 d. The last step of the OFF-phase comprises of connecting the HVPS to the AC mains supply (230 V; 50 Hz). The partial-ON phase consists of turning ON the mains supply followed by turning ON the main switch at the front panel of the HVPS. Once the DSO138 has turned on, the user can refer to the calibration chart provided at the top of the HVPS in order to find out the appropriate values for input voltage and switching frequency that need to be set to obtain the desired output high voltage. After having obtained them, the user can then set these values using the corresponding knobs provided at the front panel (Fig. 3 d). The set values for input voltage and switching frequency can be visualized using the digital voltmeter and DSO138, respectively. This marks the end of partial-ON phase. Finally, the ON-phase is a single-step phase consisting of turning on the high voltage switch provided at the back panel. After the completion of the drying experiment, all the steps and stages need to be followed in the exact reverse order for appropriate shut down. 2.4 Performance evaluation of HVPS The performance of the HVPS was evaluated by studying the effect of tuning the two input controls, namely, input voltage and switching frequency. The performance parameters that were taken into consideration were current-voltage characteristics, modes of operation, and total power consumption. 2.4.1 Current-voltage characteristics The current and voltage waveforms at the primary ( I in and V in ) and secondary ( I hv and V hv ) sides of the FBT were monitored concomitantly using oscilloscope. A resistor voltage divider comprising of twenty arms each of 1 MΩ resistor was used for monitoring V hv while the multiple-wound wire with six and seven turns were used to monitor I in and I hv , respectively. The current voltage characteristics were studied based on peak-to-peak parameters ( I in,pp , V in,pp , I hv,pp , and V hv,pp ). 2.4.2 Total power consumption The total power consumption for the HVPS ( P mains ) was provided by the mains supply and was determined based on the product of V mains and I mains , which was single phase input current through mains supply. The waveforms for I mains and V mains were concomitantly captured using oscilloscope (Yokogawa) followed by employing its built-in product function to obtain the power waveform (Fig. 7 a and Fig. 7 b). The average power ( P mains,avg ) and root mean squared power ( P mains,rms ) were obtained using the power waveform using OriginPro 2024 software. 3. Results and Discussion 3.1 Circuit for HVPS The high voltage ( V hv ) generation by the high voltage power supply (HVPS) was achieved through the means of a flyback (FBT) or line output (LOPT) transformer. The entire circuit for the HVPS (Fig. 1 ) was tested for voltage waveforms at all points (P1 to P16 in Fig. 1 ) using the external oscilloscope (Fig. 4 a). The FBT was driven by a pulsating DC voltage ( V in ) which was generated through the interaction of DC voltage ( V Q1 ) and pulses with switching frequency ( f sw ) generated through pulse width modulator (PWM). Besides providing for the means to generate V Q1 and f sw , the circuit also provided means for supplying power to the oscilloscope and fan. It can be seen in Fig. 2 a and Fig. 2 d that the AC mains voltage ( V mains ; 230 V, 50 Hz) (P1 in Fig. 1 ) was stepped down to AC voltages of V BR1−2 (P2 in Fig. 1 ) of about 30 V (amplitude) and 50 Hz; and V D1−2 of 17.5 V (amplitude) and 50 Hz (P7 in Fig. 1 ) by transformers T1 and T2, respectively. It can also be observed that V BR1−2 was rectified as V BR1 (P3 in Fig. 1 ) and V BR2 (P4 in Fig. 1 ) by the bridge rectifier BR while V D1−2 was rectified as V D1 (P8 in Fig. 1 ) and V D2 (P9 in Fig. 1 ) by the full wave rectifier composed of diodes D1 and D2. Eventually, it was observed that the rectified outputs were filtered using capacitors C1 and C2 to generate DC voltages, V C1 (P5 in Fig. 1 ) of 30 V (Fig. 2 b) and V C2 (P10 in Fig. 1 ) of 12.5 V (Fig. 2 f & Fig. 2 g), respectively. With the aid of potentiometer POT1 and transistor Q1, V C1 can be regulated as V Q1 (P6 in Fig. 1 ) from 0 V to 50 V. For one of the settings of POT1, the output V Q1 has been shown in Fig. 2 c, while for several other settings, the outputs can be found in supplementary material (Fig. S1 ). Lastly, it can be seen that the effect of charging of capacitor C1 which required time of 1.6 s to reach the maximum can not only be visualized in V C1 but also in V BR1 , V BR2 , V BR1−2 , and V Q1 as seen in their corresponding transient waveforms in Fig. 2 b and Fig. 2 c. Similarly, the effect of charging of capacitor C2 which required time of 90 ms to reach the maximum value can be visualized in the transient waveforms (Fig. 2 e, Fig. 2 g, Fig. 2 h, and Fig. 2 i) of V C2 , V D1−2 , V D1 , V D2 , V C4 (P11 in Fig. 1 ), V C5 (P12 in Fig. 1 ), V PWM (P13 in Fig. 1 ) and V Q2base (P14 in Fig. 1 ) as propagation delays. On the other hand, as seen in Fig. 2 (h), V C2 was converted to V C4 of 9 V by linear voltage regulator U2 and to V C5 of 12 V by linear voltage regulators U3 and U4. V C5 was supplied as an input to the PWM NE555 and the output from the PWM, viz. V PWM (P13 in Fig. 1 ) and V Q2base (P14 in Fig. 1 ) are shown in part (i) of Fig. 5 a. With the aid of POT2, V PWM and V Q2base can be regulated in order to vary the parameters of the pulses, namely f sw , duty ratio ( D PWM ), ON-time ( t ON ) and time period ( T PWM ) of the cycle. While the pulsating waveforms of positions P13 and P14 for one setting is shown in part (i) of Fig. 5 a, the waveforms for several other settings have been provided in supplementary material (Fig. S2). 3.2 Fabrication of HVPS The fabrication of the HVPS was performed by developing the printed circuit board (PCB) (Fig. 3 a), assembling its components (Fig. 3 b), and fixing them in the enclosure (Fig. 3 c). The fully fabricated HVPS consisted of mains switch, digital voltmeter, digital oscilloscope and probing points for it, and knobs for setting V Q1 and f sw at the front panel (Fig. 3 d) while the mains supply cable, HV switch, fuse box, high voltage and ground terminals were provided at the back panel (Fig. 3 e) of the HVPS. After the satisfactory testing of the designed circuit as described in the previous section, the testing of the two input controls V Q1 and f sw and their display by the digital voltmeter and oscilloscope DSO138 were conducted. The voltmeter which was connected at position P6 of the circuit (Fig. 1 ) displayed the value of the DC voltage V Q1 when the HVPS was in the partial-ON stage. However, upon turning on the HVPS fully, i.e. in the ON stage, it was observed that the voltage value displayed by the voltmeter dropped below the voltage value V Q1 that was set during the partial-ON stage. This was due to the change in the nature of the measured voltage from DC ( V Q1 ) during the partial-ON stage to pulsating DC ( V in ) during the ON stage. Thus, when the switch Sw2 is turned on, the voltmeter no longer displays the voltage at position P6 (Fig. 1 ) but displays the voltage across position P15 (Fig. 1 ). This dropped voltage displayed by the voltmeter was recorded for different settings of V Q1 and f sw and it can be interestingly observed that the nature of change of the dropped voltage with f sw was similar for different values set for V Q1 . It can be seen from part (iii) of Fig. 5 b that the dropped voltage followed similar trend with increasing f sw for all settings of V Q1 . This can be possibly explained based on the similarities in the waveforms of V in for same frequencies across the different settings for V Q1 as shown in Fig. 6 a. Moreover, the dropped voltage observed in ON condition for the set voltage in partial-ON condition have been illustrated in part (iv) of Fig. 5 b. This chart holds significance from a diagnostic point of view. If any of the transistors Q1 or Q2 are damaged, then the value of dropped voltage for a particular set voltage is far less than that depicted in part (iv) of Fig. 5 b. Such damages can occur due to high voltage spikes in the primary side of FBT. However, in the present system, the magnitude of such spikes were attenuated using RC snubber across the primary winding of the FBT (Fig. 1 ). The drop in the voltmeter reading can be attributed to the change in the the measured voltage from average value of DC voltage ( V Q1 ) to the average value of the pulsating DC voltage ( V in ). Furthermore, the similarities in the trends with changing frequencies can be explained on the basis of the similarities in the wave shape of V in as witnessed in Fig. 6 a and supplementary figures (Fig. S3). This may have led to similar trend in computation of mean voltage that is displayed by the digital voltmeter. The change in the nature of V in waveform shape can be explained on the basis of resonance and FBT inductance. Thus, the characterization of one of the controls V Q1 and that of its display by the voltmeter was conducted as depicted by Fig. 5 b. Another variable for controlling the input to the FBT was f sw of the pulses generated by the PWM. It was regulated using POT2 and its value along with the values of several other characteristics of the pulses, namely V max , V min , D PWM , t ON , and T cycle were displayed by the oscilloscope. It was observed that DSO138 was not a reliable instrument for recording the ordinate-based parameters i.e. voltages ( V max , V min , V avg , V rms ) however it was found to be reliable for recording the abscissa-based parameters, namely f sw , D PWM , t ON , and T cycle . Despite this, DSO138 was selected as a choice of built-in oscilloscope in the HVPS due to its low-cost, easy availability, and reliability in recording ordinate-based parameters, particularly fsw as it was majorly used in the HVPS system for setting as an input to the high voltage generating FBT. However, the reliability of DSO138 was quantitatively determined by concomitant measurement using external oscilloscope (Yokogawa) and comparing f sw , D PWM , t ON , and T cycle as depicted by DSO138 and Yokogawa. It can be seen in Fig. 5 a that in the overall operational frequency range of the PWM, which was ~ 1.8 kHz to 12 kHz, all parameters measured by DSO138 were in good agreement with corresponding measurements made using Yokogawa oscilloscope except D PWM measurement by DSO138, which was coherent with the D PWM measurement by Yokogawa only up to 56% in terms of the value and up to about 76% in terms of its linear increase with increasing f sw . The corresponding ranges in which the parameter display by DSO138 was reliable were selected to generate calibration curves which can be used for predicting these responses as measured by a standard oscilloscope (part (v) to (viii) of Fig. 5 a). It could be inferred from the slopes and intercepts of these calibration curves that the parameters, f sw , t ON , and T cycle of DSO138 were in good agreement with the standard Yokogawa parameters, thus establishing their high accuracy in the corresponding frequency ranges (part (v), (vii) & (viii) of Fig. 5 a). Thus, the characteristics of the second control input to be provided to the HVPS for the generation of HV, i.e. f sw were established. Figure 3 f depicts the overall effect of V in and f sw on V hv using a 3D plot. Based on the desired value of HV ( V hv ), the values of V in and f sw can be set using the calibration graph provided in Fig. 3 g. 3.3 Performance evaluation of HVPS The HV generation by the HVPS was based on the action of the FBT. Therefore, it was essential to study the current-voltage characteristics of the FBT. Furthermore, the HVPS had been designed for its intended use in electrohydrodynamic (EHD) drying, wherein minimization of energy is an important processing challenge in drying operations. Therefore, the quantification of total power consumption by the HVPS was conducted. Due to their aforementioned significance, current-voltage characteristics and total power consumption were selected to evaluate the performance of the HVPS system. The measurements for V hvps were made across one arm of the twenty-armed resistance voltage divider while those for I in and I hvps were made around wires with six and seven turns, respectively. Therefore, Fig. 6 a shows the waveform for V hvps that has been attenuated by factor of twenty and the waveform for I in , and I hvps that have been magnified by factors of six and seven, respectively. While Fig. 6 a shows the waveforms of V in , V hvps , I in , and I hvps for different settings of POT1 ( V in ) and POT2 ( f sw ), these waveforms for several other settings have been provided in supplementary material (Fig. S3). From Fig. 6 b, it can be seen that the current-voltage characteristics of the primary side of FBT ( I in - V in ) followed quadratic trend. The primary current ( I in ) increased in a quadratic manner with increasing primary voltage ( V in ). On the other hand, trend for change in secondary current ( I hvps ) with increasing secondary voltage ( V hvps ) was based on the individual input parameters, V in and f sw . The individual effects of V in and f sw on the primary current-voltage characteristics can be seen in part (i) and (ii) of Fig. 6 b, respectively, while their individual effects on the secondary current-voltage characteristics can be seen in part (iii) and (iv) of Fig. 6 b, respectively. At any particular set V in , the primary current, I in increased with increasing primary voltage, V in (part (i) of Fig. 6 b). On the other hand, the trend for change in the secondary current, I hvps with increasing secondary voltage, V hvps at a particular set V in , was not monotonous although it was the same across all values of V in (part (iii) of Fig. 6 b). The trend for the change in I hvps with V hvps can be better explained if visualized with respect to varying f sw as is depicted in part iv of Fig. 6 b. At any particular f sw , the secondary current-voltage ( I hvps - V hvps ) characteristics were found to be linear for all values of f sw used in the study. The maximum current that can be at any particular f sw increased with increasing f sw in the case of primary current ( I in ) (part (ii) of Fig. 6 b), however it was not monotonous in the case of secondary current ( I hvps ) (part (iv) of Fig. 6 b). Lastly, the overall effect of V in on the output high voltage ( V hvps ) followed direct relationship while that f sw was found to be inversely related to V hvps as shown in Fig. 3 f and Fig. 3 g. The waveforms for mains voltage ( V mains ), mains current ( I mains ), and total power ( P mains ) have been shown in Fig. 7 a and Fig. 7 b for different settings of V in and f sw , i.e. {20 V, 4.600 kHz} and {50 V, 2.049 kHz}, respectively. Moreover, these waveforms for several other settings of V in and f sw have been provided in supplementary material (Fig. S4). Based on the waveforms for P mains , the average ( P avg ) and root mean squared ( P rms ) power were calculated. It can be seen that in the entire domain of V in and f sw that can be set using the HVPS system, P avg ranged from 8.9166 W to 25.9251 W (Fig. 7 c) while P rms ranged from 13.4902 W to 35.2285 W (Fig. 7 d). Furthermore, the individual effects of V in and f sw on P avg and P rms can also be seen in Fig. 7 c and Fig. 7 d, respectively. At any particular f sw , both P avg and P rms increased with increasing V in . On the other hand, at any particular Vin, both P avg and P rms decreased with increasing f sw when f sw ranged from ~ 1.8 kHz to ~ 5 kHz and from ~ 6 kHz to ~ 9.5 kHz while in the f sw ranges of ~ 5 to ~ 6 kHz and ~ 9.5 to 12 kHz, P avg and P rms increased with increasing f sw . This may be due to the transition in the shape of the output voltage waveform in these ranges as depicted in Fig. 6 a. It is also noteworthy that the magnitudes of current and power consumption can vary based on the output load (which in the present study was 20 MΩ). However, this study has established the nature of characteristics of current-voltage and power consumption by the developed HVPS system. Despite the dependency of secondary current and total power on the output load, it is also noteworthy that the output high voltage ( V hvps ) is independent of the output load used. Thus, the HVPS can be used for achieving the desired output high voltage across the emitter and collector electrodes in electrohydrodynamic drying up to a peak-to-peak voltage of about 10 kV. 4. Conclusions The developed HVPS system can be used for generation of high voltages required in electrohydrodynamic drying of food and biomaterials as well as for other electrohydrodynamic applications up to a voltage of about 10 kV. The cost of the HVPS was found to be 5,588 INR while its weight was 2.4 kg. Thus, the developed HVPS system provides a low-cost and portable solution to the otherwise expensive and bulky HVPS systems that are commercially available. Furthermore, the HVPS system was appropriately calibrated based on two control inputs. The performance evaluation established the current-voltage and power requirements of the HVPS system. Overall, the present study has been completed holistically from the design and testing of circuit to the fabrication, characterization, and performance evaluation of HVPS system for electrohydrodynamic applications. This study will pave the way for design of low-cost and portable electrohydrodynamic devices such as electrohydrodynamic dryer for food products. Declarations Conflicts of interest The authors declare no conflicts of interest. Funding The work is primarily funded by the Prime Minister Research Fellowship, Ministry of Education, Government of India received by the first author. Author Contribution Anas Ejaz Yasmeen Shaikh was involved in conceptualization, designing experiments, data acquisition, analysis and interpretation, and manuscript writing and editing. Hari Niwas Mishra was involved in conceptualization, designing of experiments, supervision, and manuscript writing and editing. Acknowledgement The first author is grateful to Mr. Prosenjit Das, Senior Technician at the Electrical Engineering Department, Indian Institute of Technology Kharagpur for his dedicated assistance. Data Availability The datasets used and/or analysed during the current study available from the corresponding author on reasonable request. References Ciprian Foronda, K. D. et al. Electrohydrodynamic Drying in Agribusiness: Literature Review. Front. Sustain. Food Syst. 5 , 1–13 (2022). Reshmi, S. K., Mahalakshmi, L., Moses, A. J. & Anandharamakrishnan, C. Electrospraying and Electrospinning: Applications in the Food Industry. Non-Thermal Technol. Food Industry: Adv. Regulations . 94–111. 10.1201/9781003359302-7 (2024). Soraiyay Zafar, H., Asefi, N., Siahpoush, V., Roufegarinejad, L. & Alizadeh, A. Preparation of egg white powder using electrohydrodynamic drying method and its effect on quality characteristics and functional properties. Food Chem. 426 , 136567 (2023). Laina, K. T., Drosou, C. & Krokida, M. Comparative assessment of encapsulated essential oils through the innovative electrohydrodynamic processing and the conventional spray drying, and freeze-drying techniques. Innov. Food Sci. Emerg. Technol. 95 , 103720 (2024). Alehosseini, A., Gómez-Mascaraque, L. G. & Ghorani, B. & López-Rubio, A. Stabilization of a saffron extract through its encapsulation within electrospun/electrosprayed zein structures. LWT 113, (2019). Niu, B., Shao, P., Feng, S., Qiu, D. & Sun, P. Rheological aspects in fabricating pullulan-whey protein isolate emulsion suitable for electrospraying: Application in improving β-carotene stability. LWT 129, (2020). Gómez-Estaca, J., Gavara, R. & Hernández-Muñoz, P. Encapsulation of curcumin in electrosprayed gelatin microspheres enhances its bioaccessibility and widens its uses in food applications. Innov. Food Sci. Emerg. Technol. 29 , 302–307 (2015). Lv, H. et al. Improving structural and functional properties of starch-catechin-based green nanofiber mats for active food packaging by electrospinning and crosslinking techniques. Int. J. Biol. Macromol. 267 , 131460 (2024). Celebioglu, A. & Uyar, T. Electrohydrodynamic encapsulation of eugenol-cyclodextrin complexes in pullulan nanofibers. Food Hydrocoll. 111 , (2021). Aghababaei, F., McClements, D. J., Martinez, M. M. & Hadidi, M. Electrospun plant protein-based nanofibers in food packaging. Food Chem. 432 , 137236 (2024). Raeisi, M. et al. Physicochemical and antibacterial effect of Soy Protein Isolate/Gelatin electrospun nanofibres incorporated with Zataria multiflora and Cinnamon zeylanicum essential oils. J. Food Meas. Charact. 15 , 1116–1126 (2021). wen Jia, X. et al. Preparation and characterization of pea protein isolate-pullulan blend electrospun nanofiber films. Int. J. Biol. Macromol. 157 , 641–647 (2020). Ma, J. et al. Enhanced viability of probiotics encapsulated within synthetic/natural biopolymers by the addition of gum arabic via electrohydrodynamic processing. Food Chem. 413 , (2023). Polat, A. & Izli, N. Drying of garlic slices by electrohydrodynamic-hot air method. J. Food Process. Eng. 45 , e13980 (2022). Sumariyah, S., Khuriati, A., Pratiwi, S. H. & Fachriyah, E. Ion wind drying with input power variation of the potato slices. J. Phys. Conf. Ser. 1524 , (2020). Martynenko, A. & Zheng, W. Electrohydrodynamic drying of apple slices: Energy and quality aspects. J. Food Eng. 168 , 215–222 (2016). Dinani, S. T., Hamdami, N., Shahedi, M., Havet, M. & Queveau, D. Influence of the electrohydrodynamic process on the properties of dried button mushroom slices: A differential scanning calorimetry (DSC) study. Food Bioprod. Process. 95 , 83–95 (2015). Hu, Y., Huang, Q. & Bai, Y. Combined electrohydrodynamic (EHD) and vacuum freeze drying of shrimp. J. Phys. Conf. Ser. 418 , 012143 (2013). Johnson, M. J. & Go, D. B. Recent advances in electrohydrodynamic pumps operated by ionic winds: a review. Plasma Sources Sci. Technol. 26 , 103002 (2017). Ghorani, B. & Tucker, N. Fundamentals of electrospinning as a novel delivery vehicle for bioactive compounds in food nanotechnology. Food Hydrocoll. 51 , 227–240 (2015). Iranshahi, K., Onwude, D. I., Martynenko, A. & Defraeye, T. Dehydration mechanisms in electrohydrodynamic drying of plant-based foods. Food Bioprod. Process. 131 , 202–216 (2022). Parkash, V., Kumar, P. & Sapra, G. Design and simulation of flyback based adjustable high voltage power supply (HVPS) for electro-spinner. in AIP Conference Proceedings vol. 2276AIP Publishing, (2020). Additional Declarations The authors declare no competing interests. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5591834","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":404359882,"identity":"07de48db-5843-4263-9928-7745666901db","order_by":0,"name":"Anas Ejaz Yasmeen Shaikh","email":"data:image/png;base64,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","orcid":"","institution":"Indian Institute of Technology Kharagpur","correspondingAuthor":true,"prefix":"","firstName":"Anas","middleName":"Ejaz Yasmeen","lastName":"Shaikh","suffix":""},{"id":404359883,"identity":"f83ec35b-da71-4637-965e-9c6f32cd178a","order_by":1,"name":"Hari Niwas Mishra","email":"","orcid":"","institution":"Indian Institute of Technology Kharagpur","correspondingAuthor":false,"prefix":"","firstName":"Hari","middleName":"Niwas","lastName":"Mishra","suffix":""}],"badges":[],"createdAt":"2024-12-06 07:53:36","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-5591834/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5591834/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":74512017,"identity":"a72c9565-758c-4ee5-82a7-40ba09a28309","added_by":"auto","created_at":"2025-01-23 04:00:22","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":3703851,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic of high voltage power supply circuit\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-5591834/v1/9f8ca9ee1b5a7799662bd3f5.png"},{"id":74511982,"identity":"31d90d5e-b88f-4164-81ae-aac2851629db","added_by":"auto","created_at":"2025-01-23 04:00:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":32328774,"visible":true,"origin":"","legend":"\u003cp\u003eResponse of circuit for positions (a) P1-4, (b) P2-5, (c) P5-6, (d) P1, 7-9, (e) P1,7-9, (f) P7-10, (g) P7-10, (h) P10-12, and (i) P12-14\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-5591834/v1/6af3779a8e1619f5bb72eaec.png"},{"id":74511981,"identity":"5b4e7cb0-a13e-4e3d-9c3f-ebbe02852a56","added_by":"auto","created_at":"2025-01-23 04:00:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":26315696,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a) \u003c/strong\u003ePrinted circuit board, \u003cstrong\u003e(b)\u003c/strong\u003e component assembly, \u003cstrong\u003e(c)\u003c/strong\u003e engineering drawing of enclosure, \u003cstrong\u003e(d)\u003c/strong\u003e pictorial view of front panel, \u003cstrong\u003e(e)\u003c/strong\u003e pictorial view of back panel for high voltage power supply system, and \u003cstrong\u003e(f)\u003c/strong\u003e3D-plot for high voltage output, and \u003cstrong\u003e(g)\u003c/strong\u003ecalibration chart for high voltage output\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-5591834/v1/12d15855c9b8a54c6bf09a6d.png"},{"id":74511983,"identity":"f8bb20f6-80ca-414c-a750-a10dc0dd8536","added_by":"auto","created_at":"2025-01-23 04:00:21","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":17458157,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement set-up of current-voltage characteristics of primary and secondary sides of the flyback transformer (a) front view (b) top view\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-5591834/v1/be2701b55281772d0d164f90.png"},{"id":74511986,"identity":"493973ea-d927-4709-b276-469904e256c6","added_by":"auto","created_at":"2025-01-23 04:00:22","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":18229092,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e (i) Response for positions P13-14 as measured using external (Yokogawa) oscilloscope; (ii) response for position P14 as measured by built-in oscilloscope of the high voltage power supply; variation of frequency, duty ratio, time period, and pulse width for positive half cycle with varying potentiometer POT2 opening as recorded in (iii) external oscilloscope and (iv) built-in oscilloscope; calibration curves for (v) frequency, (vi) duty ratio, (vii) time period, and (viii) pulse width of positive half cycle.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(b)\u003c/strong\u003e \u003cstrong\u003e(i) \u003c/strong\u003eVoltage set using potentiometer POT1 as displayed by voltmeter in partial-ON stage, (ii) corresponding dropped voltage displayed during ON stage; characterization of set versus dropped voltage with varying (iii) frequency and (iv) voltage.\u003c/p\u003e\n\u003cp\u003eFigure 5B parts 3 and 4 are not available with this version.\u003c/p\u003e","description":"","filename":"Figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-5591834/v1/0fe49abc7ecc345f09bceabf.png"},{"id":74512019,"identity":"33ffc88e-19d6-478d-8fce-8d512692d38c","added_by":"auto","created_at":"2025-01-23 04:00:22","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":33238037,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e Waveforms for voltage and current of primary and secondary sides of FBT for {\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e} values of (i) {5 V, 1.897 kHz}, (ii) {5 V, 3.988 kHz}, (iii) {5 V, 5.632 kHz}, (iv) {5 V, 9.754 kHz}, (v) {5 V, 11.258 kHz}, (vi) {5 V, 12.757 kHz}, (vii) {30 V, 1.897 kHz}, (viii) {30 V, 3.988 kHz}, (ix) {30 V, 5.632 kHz}, (x) {30 V, 9.754 kHz}, (xi) {30 V, 11.258 kHz}, (xii) {30 V, 12.757 kHz}, (xiii) {50 V, 1.897 kHz}, (xiv) {50 V, 3.988 kHz}, (xv) {50 V, 5.632 kHz}, (xvi) {50 V, 9.754 kHz}, (xvii) {50 V, 11.258 kHz}, (xviii) {50 V, 12.757 kHz}\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(b)\u003c/strong\u003e Current-voltage characteristics of primary of flyback transformer with varying (i) voltage and (ii) frequency and those of secondary of flyback transformer with varying (iii) voltage and (iv) frequency\u003c/p\u003e","description":"","filename":"Figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-5591834/v1/d0fee0160d9685d70a01dbe9.png"},{"id":74512024,"identity":"ee079764-421f-46d6-b98c-6733ac8045ed","added_by":"auto","created_at":"2025-01-23 04:00:22","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":9584397,"visible":true,"origin":"","legend":"\u003cp\u003eTotal power consumption by high voltage power supply; waveforms for \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e for {\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e} of (a) {20 V, 4.600 kHz} and (b) {50 V, 2.049 kHz}; (c) average and (d) root mean squared power consumption\u003c/p\u003e","description":"","filename":"Figure7.png","url":"https://assets-eu.researchsquare.com/files/rs-5591834/v1/916de6c992804bad4be8644e.png"},{"id":74511980,"identity":"ff2388cb-9ea5-427d-8d90-1f1e5522586f","added_by":"auto","created_at":"2025-01-23 04:00:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":65321,"visible":true,"origin":"","legend":"","description":"","filename":"supplementarymaterial.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5591834/v1/c717336c2e19e83922c66e70.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"Design of High Voltage Power Supply System for Application of Electrohydrodynamic Drying","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eIn the past decade, there has been an increasing trend in the application of electrohydrodynamic (EHD) processing to food and biomaterials \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Depending on whether the application is for solid or liquid products, EHD processing can serve different purposes. In case of liquid food products, EHD processing can be used for electrospraying and electrospinning \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Electrospraying has been used to produce dried powders from liquid food matrices such as egg \u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e as well to encapsulate valuable food ingredients such as essential oils \u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e, saffron extract \u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e, β-carotene \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e, and curcumin \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. On the other hand, electrospinning can be used to produce nanofibers from viscous polymeric solutions such as those of hydrocolloids like starch \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e and pullulan \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e, and plant proteins like zein \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e, soy and gelatin \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e, and pea \u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. These nanofibers not only find applications in food packaging but also can be used as delivery systems for nutraceuticals, such as probiotics \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e through encapsulation. On the other hand, for solid food products, EHD processing has been used to dry food and biomaterials. The EHD drying technique has been applied for drying of solid food products such as slices of ginger \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, potato \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e, apple \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e, banana slices, mushroom \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e, and shrimps \u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe technique of EHD processing is based on the application of a high voltage across two electrodes with different radii of curvature. The non-uniform electric field generated between the two electrodes leads to corona discharge and the generation of an electric wind \u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. In EHD processing of liquid food products, the Taylor\u0026rsquo;s cone formation leads to the atomization of the liquid followed by spraying or spinning due to the electric wind \u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. The major components of an EHD set-up for processing of liquid foods include a high voltage power supply, syringe pump, syringe needle as emitter electrode and collector electrode. On the other hand, in EHD processing of solid foods, seven mass transfer mechanisms were identified by Iranshahi et al. (2022) and the convective effect due to electric wind was reported as a major mechanism for the drying of solid food products. The major components of an EHD set-up for processing of solid foods include a high voltage power supply, emitter and collector electrodes.\u003c/p\u003e \u003cp\u003eFor researchers in the field of food and bioprocessing, one of the hurdles to build a concise set-up for experiments on EHD processing is in the incorporation of high voltage power supply (HVPS) in the set-up. The EHD processing of food and biomaterials requires high voltages but very low currents. Some of the available HVPS commercial units that have been used in studies on EHD drying of food materials, along with their specifications for comparison have been mentioned in \u003cb\u003eTable \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/b\u003e. The HVPS systems that have been in the studies are bulky as they are manufactured to meet high current requirements and and even if they are made for meeting the requirements of lower currents, they are expensive \u003cb\u003e(Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e)\u003c/b\u003e. Furthermore, the use of a commercially available HVPS gives little opportunity to a researcher to conduct an in-depth analysis of the HVPS in such a way that it\u0026rsquo;s design can be tuned to meet the scale for different applications. A study was conducted on the design and simulation of an adjustable HVPS for electrospinner application, however, this study was only based on simulation without fabricating the power supply and the maximum voltage generated was too high \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Thus, there is a need to develop a low-cost and portable HVPS system that is particularly designed for EHD applications. There is a dearth of studies on the development of HVPS systems for EHD applications. Thus, the design of an HVPS can give the mainstream life science researchers an opportunity to understand the electrical system in a more mechanistic way rather than the black box approach involved in the use of commercially available high voltage power supplies.\u003c/p\u003e \u003cp\u003eIn this study, a low-cost and portable HVPS system has been designed, fabricated, and tested, to EHD drying process. Given its easy and widespread availability, flyback or line output transformer has been incorporated for generation of high voltage in the HVPS system. This study lays a foundation for the design of HVPS systems for EHD drying of solid foods and can prove to be a useful tool in the design and development of EHD dryers in the future.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials\u003c/h2\u003e \u003cp\u003eAll electronic components including construction materials for fabrication used in this study have been listed in Table S2 and were procured from local shops or online purchase.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Circuit for HVPS\u003c/h2\u003e \u003cp\u003eIn this section, the design, measurement, and control requirements of the electrical circuit for the HVPS have been described.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1 Design requirement\u003c/h2\u003e \u003cp\u003eThe voltage requirements for EHD drying was set as 0 to 10 kV. The high voltage generation was achieved primarily through the flyback transformer (FBT) or line output transformer (LOPT) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The required output DC high voltage from the FBT and thereby from the HVPS system (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) was adjusted using two input controls, namely input pulsating DC voltage supplied to the FBT (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) and switching frequency of pulse width modulator (\u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003eSW\u003c/em\u003e\u003c/sub\u003e). The magnitude of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e was determined by the uppermost part of the circuit shown by the schematic in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e by construction of a DC-bus comprising of step-down transformer T1, bridge rectifier BR1, capacitor filter C1, bleeder resistor R1 and LED1 for indicating discharging followed by potentiometer Pot1 for controlling the output of transistor Q1. On the other hand, the frequency and duty ratio of this pulsating DC input voltage Vin to the FBT was controlled using pulse width modulator NE555 and transistor Q2 along with diode D3 served as switch for transforming the output at emitter of Q1 to pulsating DC to be fed as input to the FBT. The ripples in the PWM output were minimized by capacitor C8.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe lower part of the circuit shown in the schematic in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e consisted of a second DC-bus made up of center-tapped step-down transformer T2, full wave rectifier made using diodes D1 and D2, and capacitor filter C2. This circuit was followed by linear voltage regulators U2 (LM7809), and U3 and U4 (LM78L12 each) for obtaining regulated output voltages of 9 V, and 12 V, respectively, to power auxiliary devices of the HVPS. A DC fan powered at 12 V using LM78L12 was used for removal of heat generated in the circuit and heat sinks were attached to the transistors Q1 and Q2 (each BU536) and bridge rectifier block for heat dissipation. The 12 V voltage generated using voltage regulator LM78L12 was also used for powering the digital voltmeter at the front panel of the HVPS (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed) as well as for PWM while the 9 V generated using voltage regulator LM7809 was used to power the digital oscilloscope DSO138 which is also at the front panel of the HVPS (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). Similar to the DC-bus in upper part of the circuit, bleeder resistor R2 and LED2 for indicating discharging were provided.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe PWM was assembled in astable mode using standard assembly comprising of resistor R3, potentiometer POT2, and capacitors C6 and C7. The output current from the HVPS (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) was limited in the desired range using a resistance voltage divider comprising of twenty resistors of 1 MΩ each attached at the output of the FBT. The design requirements for circuit protection were met by using a fuse of 2 A at input. Moreover, separate switches, Sw1 and Sw2, were provided for mains and high voltage, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Furthermore, an RC circuit (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) comprising of parallel combination of capacitor (10 nF; 1 kV) and resistance (1.5 kΩ) was used as a snubber across the transistor Q2 for protecting it against high voltage spikes (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The specifications of all the electronic components as well as other construction materials used in the design and fabrication of the HVPS have been summarized in Table S2.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2 Measurement requirement\u003c/h2\u003e \u003cp\u003eThe primary measurement requirements for the HVPS system include those for the output high voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) and current (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e). The high voltage generated in the HVPS was a result of the input voltage to the flyback transformer (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) and the output parameters of the of the pulse width modulator, namely duty ratio (\u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e) and switching frequency (\u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e). The average value of the input voltage to the flyback transformer (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein,avg\u003c/em\u003e\u003c/sub\u003e) was displayed by the digital voltmeter attached at the front panel of the HVPS (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed) while the waveform for \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e was captured using 50:1 differential probe of oscilloscope (DLM3024, Yokogawa, Japan) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ea) at the front panel of the HVPS system. On the other hand, the output of the pulse width modulator was monitored using the digital oscilloscope (DSO138, JYE Tech) which was incorporated as a part of the HVPS system. Thus, the values for the duty ratio (\u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e) and switching frequency (\u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e) were procured from the DSO138 reading (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). For this two probing points were provided at the front side of the HVPS system from which the DSO138 probes were connected (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). The DSO was powered at 9 V using voltage regulator, LM7809 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). For given values of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e or \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003eSW\u003c/em\u003e\u003c/sub\u003e, the output high voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) values were measured using voltage divider comprising of 20 arms of resistors each with value of 1 MΩ (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003eb).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe output voltage across one arm closest to the ground terminal of the HVPS was recorded using a 100:1 probe (Multicomp PRO MP770217) in the oscilloscope (DLM3024, Yokogawa, Japan) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ea). Based on these parameters, calibration charts mapping the input parameters (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003eSW\u003c/em\u003e\u003c/sub\u003e) to the output parameter (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) was prepared (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ef and Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eg). The calibration chart can be used to obtain \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003eSW\u003c/em\u003e\u003c/sub\u003e to get the desired output high voltage from the HVPS. For measurement of current through the primary winding of FBT (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) and output current from the HVPS system (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e), a Techtronix differential current probe set at 0.1A/V was used for recording in the Yokogawa oscillosope (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ea). Since the currents \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e are very small, the measurements through the current probes were performed through seven- and six-turn windings, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003eb), thus these responses recorded through the oscilloscope represent seven- and six-times magnified currents, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003ea). The experiments for measuring and recording waveforms of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e under different settings of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003eSW\u003c/em\u003e\u003c/sub\u003e consisted of one set of experiments. On the other hand, the measurement of input power required by the HVPS system through the mains (\u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e) under different settings of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003eSW\u003c/em\u003e\u003c/sub\u003e comprised of another set of experiments. The details for measurement of \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e have been provided in section 2.4.2. These voltage measurements were performed at sixteen points shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe HVPS offered only two probe points at its front panel (shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed) corresponding to \u0026lsquo;P14\u0026rsquo; and ground as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The additional probes for the other fifteen points of measurement were obtained through the components assembled (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eb) on the PCB (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e(a)) by opening the enclosure.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3 Control requirement\u003c/h2\u003e \u003cp\u003eThe output voltage from the flyback transformer (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) was controlled using the analog regulators provided at the front panel of the system (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). One of the regulators (Pot1 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) was used to control the input voltage to the flyback (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) while the other one (Pot2 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) was used to control duty ratio (\u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e) and switching frequency (\u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003eSW\u003c/em\u003e\u003c/sub\u003e) of the pulse width modulator in the astable mode. These regulators have also been depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed. Moreover, as a safety measure, a switch (Sw2 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) for input voltage to the flyback transformer (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) was provided at the back panel of the system (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ee) in addition to the mains switch (Sw1 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) provided at the front panel of the system (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed).\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Fabrication of HVPS\u003c/h2\u003e \u003cp\u003eThe electrical circuit designed and simulated was subsequently fabricated to develop the high voltage power supply.\u003c/p\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e2.3.1 Hardware description\u003c/h2\u003e \u003cp\u003eThe main external hardware element of the high voltage power supply consisted of the output high voltage and ground terminals to be connected to the emitter and collector electrodes, respectively. These terminals were designed to be at the back panel of the system (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ee). The terminals were connected to the electrodes using alligator cables, which are accessories with the HVPS system. Besides, the mains supply cable for AC (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003erms_mains\u003c/em\u003e\u003c/sub\u003e = 230 V; \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e = 50 Hz), high voltage switch, and fuse box were among other external hardware elements that were provided at the back panel of the HVPS. On the other hand, the mains switch, regulators for potentiometers, oscilloscope along with its buttons and power cable, voltage probes after the pulse width modulator, and digital voltmeter were among other external hardware elements that consisted of the front panel of the HVPS system (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). The enclosure for the HVPS has been designed in such a way that it can be easily opened for diagnostic purposes with the two LED\u0026rsquo;s provided in the circuit serving as preliminary diagnostic tools. The internal hardware consisted of the circuit assembly based on the designed circuit (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and the elements used have been listed in Table S2. The details about the electronic hardware have been specified in section 2.2.1.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.3.2 Enclosure for HVPS\u003c/h2\u003e \u003cp\u003eThe enclosure for the HVPS was made using transparent acrylic sheet of thicknesses 2.79 mm and 1.93 mm to ensure insulation for the high voltage circuit. The enclosure was designed to make the system compact (size: 124 mm \u0026times; 263 mm \u0026times; 85 mm) and light in weight (2.397 kg). The enclosure also consisted of compartment for housing the digital oscilloscope. The enclosure was also designed to incorporate suitable sections for cables of mains supply and of DSO power supply. It also provided sections for high voltage and ground terminals. Furthermore, the enclosure was provided with clearance at the bottom using four acrylic stands. The enclosure was colored using metallic silver spray paint (Rust Oleum 1915830). The dimensions of the enclosure have been provided in the engineering drawing (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ec) constructed using Solidworks 2022 software.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.3.3 Bill of materials\u003c/h2\u003e \u003cp\u003eThe bill of materials for the electronic components and other building materials, such as acrylic sheet and color, used in the fabrication of the high voltage power supply system has been provided in Table S2. The acrylic sheet of thickness 2.79 mm was used to fabricate the bottom support of the enclosure to provide mechanical strength for holding the electrical circuit while the acrylic sheet of thickness 1.93 mm was used to fabricate the top cover of the enclosure as its cost was lower than the former sheet. The cost of raw material for manufacturing one unit of the power supply was estimated using it.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e2.3.4 Build instructions\u003c/h2\u003e \u003cp\u003eBased on the designed circuit, the printed circuit board (PCB) was designed and fabricated on a 2 mm general purpose board by etching (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). The electronic components were then assembled on the board (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). The enclosure was prepared separately with the sections cut out for the external hardware elements described in section 2.3.1. The enclosure was colored on its outside surface with metallic silver spray paint. The assembled PCB was fitted into the enclosure and the external hardware were installed in the cut sections and connected to appropriate positions on the PCB. After the installation, the enclosure top cover was attached to complete the build-up of the high voltage power supply.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e2.3.5 Voltage calibration\u003c/h2\u003e \u003cp\u003eVoltage calibration was performed to find out the value of high voltage output (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv\u003c/em\u003e\u003c/sub\u003e) for set values of the two inputs to the FBT, namely, input voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) and switching frequency of the pulse width modulator (\u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e). The peak-to-peak voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv,pp\u003c/em\u003e\u003c/sub\u003e) was used as indicator of the high voltage output. The output high voltage was monitored using Yokogawa across one arm of the resistance voltage divider. Calibration charts depicting the high voltage response, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e for different values of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e were generated to determine the high voltage output for the corresponding input settings.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e \u003ch2\u003e2.3.6 Operation instructions\u003c/h2\u003e \u003cp\u003eThe overall operation of the HVPS for electrohydrodynamic drying can be divided into three phases, namely, OFF-phase, partial-ON-phase, and ON-phase. The OFF phase is when none of the two switches are ON and consists primarily of connecting all the accessories. To complete this phase, firstly the high voltage and ground probes provided at the back panel need to be connected using cables, respectively, to the emitter and collector electrodes of the electrohydrodynamic drying experimental setup. This is followed by connecting DSO138 to the appropriate probe points provided at the front panel as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed. The last step of the OFF-phase comprises of connecting the HVPS to the AC mains supply (230 V; 50 Hz). The partial-ON phase consists of turning ON the mains supply followed by turning ON the main switch at the front panel of the HVPS. Once the DSO138 has turned on, the user can refer to the calibration chart provided at the top of the HVPS in order to find out the appropriate values for input voltage and switching frequency that need to be set to obtain the desired output high voltage. After having obtained them, the user can then set these values using the corresponding knobs provided at the front panel (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). The set values for input voltage and switching frequency can be visualized using the digital voltmeter and DSO138, respectively. This marks the end of partial-ON phase. Finally, the ON-phase is a single-step phase consisting of turning on the high voltage switch provided at the back panel. After the completion of the drying experiment, all the steps and stages need to be followed in the exact reverse order for appropriate shut down.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Performance evaluation of HVPS\u003c/h2\u003e \u003cp\u003eThe performance of the HVPS was evaluated by studying the effect of tuning the two input controls, namely, input voltage and switching frequency. The performance parameters that were taken into consideration were current-voltage characteristics, modes of operation, and total power consumption.\u003c/p\u003e \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e \u003ch2\u003e2.4.1 Current-voltage characteristics\u003c/h2\u003e \u003cp\u003eThe current and voltage waveforms at the primary (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) and secondary (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv\u003c/em\u003e\u003c/sub\u003e) sides of the FBT were monitored concomitantly using oscilloscope. A resistor voltage divider comprising of twenty arms each of 1 MΩ resistor was used for monitoring \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv\u003c/em\u003e\u003c/sub\u003e while the multiple-wound wire with six and seven turns were used to monitor \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv\u003c/em\u003e\u003c/sub\u003e, respectively. The current voltage characteristics were studied based on peak-to-peak parameters (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein,pp\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein,pp\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv,pp\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv,pp\u003c/em\u003e\u003c/sub\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003e2.4.2 Total power consumption\u003c/h2\u003e \u003cp\u003eThe total power consumption for the HVPS (\u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e) was provided by the mains supply and was determined based on the product of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e, which was single phase input current through mains supply. The waveforms for \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e were concomitantly captured using oscilloscope (Yokogawa) followed by employing its built-in product function to obtain the power waveform (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003ea and Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003eb). The average power (\u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003emains,avg\u003c/em\u003e\u003c/sub\u003e) and root mean squared power (\u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003emains,rms\u003c/em\u003e\u003c/sub\u003e) were obtained using the power waveform using OriginPro 2024 software.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Circuit for HVPS\u003c/h2\u003e \u003cp\u003eThe high voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv\u003c/em\u003e\u003c/sub\u003e) generation by the high voltage power supply (HVPS) was achieved through the means of a flyback (FBT) or line output (LOPT) transformer. The entire circuit for the HVPS (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) was tested for voltage waveforms at all points (P1 to P16 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) using the external oscilloscope (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003ea). The FBT was driven by a pulsating DC voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) which was generated through the interaction of DC voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e) and pulses with switching frequency (\u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e) generated through pulse width modulator (PWM). Besides providing for the means to generate \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e, the circuit also provided means for supplying power to the oscilloscope and fan.\u003c/p\u003e \u003cp\u003eIt can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003ea and Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003ed that the AC mains voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e; 230 V, 50 Hz) (P1 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) was stepped down to AC voltages of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eBR1\u0026minus;2\u003c/em\u003e\u003c/sub\u003e (P2 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) of about 30 V (amplitude) and 50 Hz; and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eD1\u0026minus;2\u003c/em\u003e\u003c/sub\u003e of 17.5 V (amplitude) and 50 Hz (P7 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) by transformers T1 and T2, respectively. It can also be observed that \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eBR1\u0026minus;2\u003c/em\u003e\u003c/sub\u003e was rectified as \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eBR1\u003c/em\u003e\u003c/sub\u003e (P3 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eBR2\u003c/em\u003e\u003c/sub\u003e (P4 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) by the bridge rectifier BR while \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eD1\u0026minus;2\u003c/em\u003e\u003c/sub\u003e was rectified as \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eD1\u003c/em\u003e\u003c/sub\u003e (P8 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eD2\u003c/em\u003e\u003c/sub\u003e (P9 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) by the full wave rectifier composed of diodes D1 and D2. Eventually, it was observed that the rectified outputs were filtered using capacitors C1 and C2 to generate DC voltages, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC1\u003c/em\u003e\u003c/sub\u003e (P5 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) of 30 V (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003eb) and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC2\u003c/em\u003e\u003c/sub\u003e (P10 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) of 12.5 V (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003ef \u0026amp; Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003eg), respectively. With the aid of potentiometer POT1 and transistor Q1, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC1\u003c/em\u003e\u003c/sub\u003e can be regulated as \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e (P6 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) from 0 V to 50 V. For one of the settings of POT1, the output \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e has been shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, while for several other settings, the outputs can be found in supplementary material (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). Lastly, it can be seen that the effect of charging of capacitor C1 which required time of 1.6 s to reach the maximum can not only be visualized in \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC1\u003c/em\u003e\u003c/sub\u003e but also in V\u003csub\u003eBR1\u003c/sub\u003e, V\u003csub\u003eBR2\u003c/sub\u003e, V\u003csub\u003eBR1\u0026minus;2\u003c/sub\u003e, and V\u003csub\u003eQ1\u003c/sub\u003e as seen in their corresponding transient waveforms in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003eb and Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003ec. Similarly, the effect of charging of capacitor C2 which required time of 90 ms to reach the maximum value can be visualized in the transient waveforms (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003ee, Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003eg, Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003eh, and Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003ei) of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC2\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eD1\u0026minus;2\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eD1\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eD2\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC4\u003c/em\u003e\u003c/sub\u003e (P11 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC5\u003c/em\u003e\u003c/sub\u003e (P12 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e (P13 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ2base\u003c/em\u003e\u003c/sub\u003e (P14 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) as propagation delays. On the other hand, as seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e2\u003c/span\u003e(h), \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC2\u003c/em\u003e\u003c/sub\u003e was converted to \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC4\u003c/em\u003e\u003c/sub\u003e of 9 V by linear voltage regulator U2 and to \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC5\u003c/em\u003e\u003c/sub\u003e of 12 V by linear voltage regulators U3 and U4. \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eC5\u003c/em\u003e\u003c/sub\u003e was supplied as an input to the PWM NE555 and the output from the PWM, viz. \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e (P13 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ2base\u003c/em\u003e\u003c/sub\u003e (P14 in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) are shown in part (i) of Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e5\u003c/span\u003ea. With the aid of POT2, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ2base\u003c/em\u003e\u003c/sub\u003e can be regulated in order to vary the parameters of the pulses, namely \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e, duty ratio (\u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e), ON-time (\u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003eON\u003c/em\u003e\u003c/sub\u003e) and time period (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e) of the cycle. While the pulsating waveforms of positions P13 and P14 for one setting is shown in part (i) of Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, the waveforms for several other settings have been provided in supplementary material (Fig. S2).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Fabrication of HVPS\u003c/h2\u003e \u003cp\u003eThe fabrication of the HVPS was performed by developing the printed circuit board (PCB) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ea), assembling its components (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eb), and fixing them in the enclosure (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). The fully fabricated HVPS consisted of mains switch, digital voltmeter, digital oscilloscope and probing points for it, and knobs for setting \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e at the front panel (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ed) while the mains supply cable, HV switch, fuse box, high voltage and ground terminals were provided at the back panel (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ee) of the HVPS. After the satisfactory testing of the designed circuit as described in the previous section, the testing of the two input controls \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e and their display by the digital voltmeter and oscilloscope DSO138 were conducted. The voltmeter which was connected at position P6 of the circuit (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) displayed the value of the DC voltage \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e when the HVPS was in the partial-ON stage. However, upon turning on the HVPS fully, i.e. in the ON stage, it was observed that the voltage value displayed by the voltmeter dropped below the voltage value \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e that was set during the partial-ON stage. This was due to the change in the nature of the measured voltage from DC (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e) during the partial-ON stage to pulsating DC (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) during the ON stage. Thus, when the switch Sw2 is turned on, the voltmeter no longer displays the voltage at position P6 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) but displays the voltage across position P15 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). This dropped voltage displayed by the voltmeter was recorded for different settings of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e and it can be interestingly observed that the nature of change of the dropped voltage with \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e was similar for different values set for \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e. It can be seen from part (iii) of Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e5\u003c/span\u003eb that the dropped voltage followed similar trend with increasing \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e for all settings of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e. This can be possibly explained based on the similarities in the waveforms of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e for same frequencies across the different settings for \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003ea. Moreover, the dropped voltage observed in ON condition for the set voltage in partial-ON condition have been illustrated in part (iv) of Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e5\u003c/span\u003eb. This chart holds significance from a diagnostic point of view. If any of the transistors Q1 or Q2 are damaged, then the value of dropped voltage for a particular set voltage is far less than that depicted in part (iv) of Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e5\u003c/span\u003eb. Such damages can occur due to high voltage spikes in the primary side of FBT. However, in the present system, the magnitude of such spikes were attenuated using RC snubber across the primary winding of the FBT (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The drop in the voltmeter reading can be attributed to the change in the the measured voltage from average value of DC voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e) to the average value of the pulsating DC voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e). Furthermore, the similarities in the trends with changing frequencies can be explained on the basis of the similarities in the wave shape of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e as witnessed in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003ea and supplementary figures (Fig. S3). This may have led to similar trend in computation of mean voltage that is displayed by the digital voltmeter. The change in the nature of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e waveform shape can be explained on the basis of resonance and FBT inductance. Thus, the characterization of one of the controls \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eQ1\u003c/em\u003e\u003c/sub\u003e and that of its display by the voltmeter was conducted as depicted by Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e5\u003c/span\u003eb.\u003c/p\u003e \u003cp\u003eAnother variable for controlling the input to the FBT was \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e of the pulses generated by the PWM. It was regulated using POT2 and its value along with the values of several other characteristics of the pulses, namely \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003emax\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003emin\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003eON\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ecycle\u003c/em\u003e\u003c/sub\u003e were displayed by the oscilloscope. It was observed that DSO138 was not a reliable instrument for recording the ordinate-based parameters i.e. voltages (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003emax\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003emin\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003eavg\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003erms\u003c/em\u003e\u003c/sub\u003e) however it was found to be reliable for recording the abscissa-based parameters, namely \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003eON\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ecycle\u003c/em\u003e\u003c/sub\u003e. Despite this, DSO138 was selected as a choice of built-in oscilloscope in the HVPS due to its low-cost, easy availability, and reliability in recording ordinate-based parameters, particularly fsw as it was majorly used in the HVPS system for setting as an input to the high voltage generating FBT. However, the reliability of DSO138 was quantitatively determined by concomitant measurement using external oscilloscope (Yokogawa) and comparing \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003eON\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ecycle\u003c/em\u003e\u003c/sub\u003e as depicted by DSO138 and Yokogawa. It can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e5\u003c/span\u003ea that in the overall operational frequency range of the PWM, which was ~\u0026thinsp;1.8 kHz to 12 kHz, all parameters measured by DSO138 were in good agreement with corresponding measurements made using Yokogawa oscilloscope except \u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e measurement by DSO138, which was coherent with the \u003cem\u003eD\u003c/em\u003e\u003csub\u003e\u003cem\u003ePWM\u003c/em\u003e\u003c/sub\u003e measurement by Yokogawa only up to 56% in terms of the value and up to about 76% in terms of its linear increase with increasing \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e. The corresponding ranges in which the parameter display by DSO138 was reliable were selected to generate calibration curves which can be used for predicting these responses as measured by a standard oscilloscope (part (v) to (viii) of Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e5\u003c/span\u003ea). It could be inferred from the slopes and intercepts of these calibration curves that the parameters, \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003eON\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ecycle\u003c/em\u003e\u003c/sub\u003e of DSO138 were in good agreement with the standard Yokogawa parameters, thus establishing their high accuracy in the corresponding frequency ranges (part (v), (vii) \u0026amp; (viii) of Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e5\u003c/span\u003ea). Thus, the characteristics of the second control input to be provided to the HVPS for the generation of HV, i.e. \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e were established. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ef depicts the overall effect of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e on \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv\u003c/em\u003e\u003c/sub\u003e using a 3D plot. Based on the desired value of HV (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehv\u003c/em\u003e\u003c/sub\u003e), the values of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e can be set using the calibration graph provided in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eg.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Performance evaluation of HVPS\u003c/h2\u003e \u003cp\u003eThe HV generation by the HVPS was based on the action of the FBT. Therefore, it was essential to study the current-voltage characteristics of the FBT. Furthermore, the HVPS had been designed for its intended use in electrohydrodynamic (EHD) drying, wherein minimization of energy is an important processing challenge in drying operations. Therefore, the quantification of total power consumption by the HVPS was conducted. Due to their aforementioned significance, current-voltage characteristics and total power consumption were selected to evaluate the performance of the HVPS system.\u003c/p\u003e \u003cp\u003eThe measurements for \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e were made across one arm of the twenty-armed resistance voltage divider while those for \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e were made around wires with six and seven turns, respectively. Therefore, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003ea shows the waveform for \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e that has been attenuated by factor of twenty and the waveform for \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e that have been magnified by factors of six and seven, respectively. While Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003ea shows the waveforms of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e for different settings of POT1 (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) and POT2 (\u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e), these waveforms for several other settings have been provided in supplementary material (Fig. S3). From Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003eb, it can be seen that the current-voltage characteristics of the primary side of FBT (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e-\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) followed quadratic trend. The primary current (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) increased in a quadratic manner with increasing primary voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e). On the other hand, trend for change in secondary current (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) with increasing secondary voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) was based on the individual input parameters, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e. The individual effects of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e on the primary current-voltage characteristics can be seen in part (i) and (ii) of Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003eb, respectively, while their individual effects on the secondary current-voltage characteristics can be seen in part (iii) and (iv) of Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003eb, respectively. At any particular set \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, the primary current, \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e increased with increasing primary voltage, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e (part (i) of Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003eb). On the other hand, the trend for change in the secondary current, \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e with increasing secondary voltage, \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e at a particular set \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e, was not monotonous although it was the same across all values of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e (part (iii) of Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003eb). The trend for the change in \u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e with \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e can be better explained if visualized with respect to varying \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e as is depicted in part iv of Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003eb. At any particular \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e, the secondary current-voltage (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e-\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) characteristics were found to be linear for all values of \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e used in the study. The maximum current that can be at any particular \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e increased with increasing \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e in the case of primary current (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e) (part (ii) of Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003eb), however it was not monotonous in the case of secondary current (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) (part (iv) of Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003eb). Lastly, the overall effect of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e on the output high voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) followed direct relationship while that \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e was found to be inversely related to \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003ef and Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003eg.\u003c/p\u003e \u003cp\u003eThe waveforms for mains voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e), mains current (\u003cem\u003eI\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e), and total power (\u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e) have been shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003ea and Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003eb for different settings of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e, i.e. {20 V, 4.600 kHz} and {50 V, 2.049 kHz}, respectively. Moreover, these waveforms for several other settings of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e have been provided in supplementary material (Fig. S4). Based on the waveforms for \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003emains\u003c/em\u003e\u003c/sub\u003e, the average (\u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003eavg\u003c/em\u003e\u003c/sub\u003e) and root mean squared (\u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003erms\u003c/em\u003e\u003c/sub\u003e) power were calculated. It can be seen that in the entire domain of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e that can be set using the HVPS system, \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003eavg\u003c/em\u003e\u003c/sub\u003e ranged from 8.9166 W to 25.9251 W (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003ec) while \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003erms\u003c/em\u003e\u003c/sub\u003e ranged from 13.4902 W to 35.2285 W (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003ed). Furthermore, the individual effects of \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e on \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003eavg\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003erms\u003c/em\u003e\u003c/sub\u003e can also be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003ec and Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e7\u003c/span\u003ed, respectively. At any particular \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e, both \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003eavg\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003erms\u003c/em\u003e\u003c/sub\u003e increased with increasing \u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ein\u003c/em\u003e\u003c/sub\u003e. On the other hand, at any particular Vin, both \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003eavg\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003erms\u003c/em\u003e\u003c/sub\u003e decreased with increasing \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e when \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e ranged from ~\u0026thinsp;1.8 kHz to ~\u0026thinsp;5 kHz and from ~\u0026thinsp;6 kHz to ~\u0026thinsp;9.5 kHz while in the \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e ranges of ~\u0026thinsp;5 to ~\u0026thinsp;6 kHz and ~\u0026thinsp;9.5 to 12 kHz, \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003eavg\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eP\u003c/em\u003e\u003csub\u003e\u003cem\u003erms\u003c/em\u003e\u003c/sub\u003e increased with increasing \u003cem\u003ef\u003c/em\u003e\u003csub\u003e\u003cem\u003esw\u003c/em\u003e\u003c/sub\u003e. This may be due to the transition in the shape of the output voltage waveform in these ranges as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003ea. It is also noteworthy that the magnitudes of current and power consumption can vary based on the output load (which in the present study was 20 MΩ). However, this study has established the nature of characteristics of current-voltage and power consumption by the developed HVPS system. Despite the dependency of secondary current and total power on the output load, it is also noteworthy that the output high voltage (\u003cem\u003eV\u003c/em\u003e\u003csub\u003e\u003cem\u003ehvps\u003c/em\u003e\u003c/sub\u003e) is independent of the output load used. Thus, the HVPS can be used for achieving the desired output high voltage across the emitter and collector electrodes in electrohydrodynamic drying up to a peak-to-peak voltage of about 10 kV.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eThe developed HVPS system can be used for generation of high voltages required in electrohydrodynamic drying of food and biomaterials as well as for other electrohydrodynamic applications up to a voltage of about 10 kV. The cost of the HVPS was found to be 5,588 INR while its weight was 2.4 kg. Thus, the developed HVPS system provides a low-cost and portable solution to the otherwise expensive and bulky HVPS systems that are commercially available. Furthermore, the HVPS system was appropriately calibrated based on two control inputs. The performance evaluation established the current-voltage and power requirements of the HVPS system. Overall, the present study has been completed holistically from the design and testing of circuit to the fabrication, characterization, and performance evaluation of HVPS system for electrohydrodynamic applications. This study will pave the way for design of low-cost and portable electrohydrodynamic devices such as electrohydrodynamic dryer for food products.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflicts of interest\u003c/h2\u003e\n\u003cp\u003eThe authors declare no conflicts of interest.\u003c/p\u003e\n\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThe work is primarily funded by the Prime Minister Research Fellowship, Ministry of Education, Government of India received by the first author.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eAnas Ejaz Yasmeen Shaikh was involved in conceptualization, designing experiments, data acquisition, analysis and interpretation, and manuscript writing and editing. Hari Niwas Mishra was involved in conceptualization, designing of experiments, supervision, and manuscript writing and editing.\u003c/p\u003e\n\u003ch2\u003eAcknowledgement\u003c/h2\u003e\n\u003cp\u003eThe first author is grateful to Mr. Prosenjit Das, Senior Technician at the Electrical Engineering Department, Indian Institute of Technology Kharagpur for his dedicated assistance.\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCiprian Foronda, K. D. et al. Electrohydrodynamic Drying in Agribusiness: Literature Review. \u003cem\u003eFront. Sustain. Food Syst.\u003c/em\u003e \u003cb\u003e5\u003c/b\u003e, 1\u0026ndash;13 (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eReshmi, S. K., Mahalakshmi, L., Moses, A. 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Design and simulation of flyback based adjustable high voltage power supply (HVPS) for electro-spinner. in \u003cem\u003eAIP Conference Proceedings\u003c/em\u003e vol. 2276AIP Publishing, (2020).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Indian Institute of Technology Kharagpur","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":false,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Electrohydrodynamic drying, Food, High Voltage Power Supply, Design, Fabrication, Performance evaluation","lastPublishedDoi":"10.21203/rs.3.rs-5591834/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5591834/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eElectrohydrodynamic (EHD) drying is an emerging technique for energy-efficient, non-thermal, and high-quality drying of food and biomaterials. It is based on enhancement of moisture removal from food material under action of electric wind resulting from corona discharge, which is generated when high voltage is applied across two electrodes with different radii of curvature. A high voltage power supply (HVPS) is an important component in experimental set-up for studying EHD drying process. In the present study, an HVPS for EHD drying of food has been developed based on its design, measurement, and control requirements. A flyback or line output transformer was used to generate high voltage up to range of 10 kV (peak-to-peak output voltage). Performance of HVPS was evaluated using current-voltage characteristics and power consumption. Maximum peak-to-peak output current obtained was ~\u0026thinsp;450 mA under load of 20 MΩ. Average and root mean-squared power of HVPS ranged from 9 to 26 W and 13 to 35 W, respectively. Cost and weight of HVPS were 5,588 INR and 2.4 kg, respectively. Thus, the designed HVPS offered low-cost and portable solution to generate high voltage for electrohydrodynamic drying. This research will expedite the process for development of electrohydrodynamic dryers for food industry.\u003c/p\u003e","manuscriptTitle":"Design of High Voltage Power Supply System for Application of Electrohydrodynamic Drying","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-23 04:00:16","doi":"10.21203/rs.3.rs-5591834/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6e608bf2-1d9a-42be-ba4b-2b6e64514d11","owner":[],"postedDate":"January 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":43104929,"name":"Physical sciences/Engineering/Chemical engineering"},{"id":43104930,"name":"Physical sciences/Engineering/Electrical and electronic engineering"},{"id":43104931,"name":"Health sciences/Health care/Nutrition"}],"tags":[],"updatedAt":"2025-01-23T04:00:16+00:00","versionOfRecord":[],"versionCreatedAt":"2025-01-23 04:00:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5591834","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5591834","identity":"rs-5591834","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}