Transient Analysis of ZCS PWM Converter Based on Equivalent Small Parameter Method

This letter proposes a nonlinear mathematical model for a zero-current-switching (ZCS) pulse width modulation (PWM) Buck converter and obtains the approximate analytical solutions of state variables using the equivalent small parameter method (ESPM). First, the operating modes of the converter are analyzed, and the equivalent circuit model together with a unified nonlinear mathematical description can be derived. Then, ESPM is adopted to solve this model, and approximate analytical solutions of state variables in both transient process and steady-state operation are obtained. The acquired results are verified by simulations and experiments finally. Since the ESPM combines the peculiarity of the perturbation method and harmonic balance method, the results obtained by ESPM are accurate and have obvious advantages compared with other methods.