ZVS frequency analysis of a current-fed resonant converter

ZVS (zero voltage switching) is a basic control strategy for normal current-fed DC-AC parallel resonant converters. However, the ZVS operating frequency and how it varies with the load and system parameters remains an unsolved theoretical problem of practical importance. After identifying different types of resonant frequencies of a typical resonant tank of a current-fed resonant converter, this paper gives both accurate numerical solution and approximate analytical solution of ZVS frequencies. The analysis is based on a step current injection model in a half-switching cycle. The validity of the analysis is proven with PSpice simulation results