Advanced AC Equivalent Circuit Modeling of PWM Converters Using Averaged and State‐Space Techniques

In many modern power electronic systems, accurate modeling is critical for effective control design and overall system performance. This paper examines the derivation of AC equivalent circuit models for pulse‐width modulated (PWM) converters operating in the continuous conduction mode. The primary goal is to isolate the significant low‐frequency behavior of converters by removing the high‐frequency switching components inherent to their operation. To accomplish this, the paper outlines both state‐space averaging and circuit averaging techniques, emphasizing how inductor currents and capacitor voltages can be approximated by averaged quantities over one switching period. Derivations are presented for key topologies—including buck, boost, and buck‐boost converters—to demonstrate the process of constructing small‐signal transfer functions. Practical considerations such as conduction losses, diode drops, and on‐resistance effects are also integrated to reflect real‐world conditions. By capturing the essential dynamics in a linearized form, these averaged models enable standard analytical tools (such as Bode plot analysis) to guide controller design, stability assessments, and transient response optimizations. Concluding remarks highlight the versatility of these methods and recommend directions for future exploration, including extensions to discontinuous conduction and resonant modes. The results underscore the value of averaged modeling as a foundation for robust and efficient power converter design.