Modulation with Full-Range Zero Voltage Switching and Current Peak Optimization for AC–DC Converter

To address the issues of limited soft-switching range and high inductor current peak in traditional single phase shift (SPS) modulation for AC–DC converters under a wide range of voltage conversion ratio conditions, this paper proposes an optimized modulation strategy based on SPS modulation. First, the steady-state operating characteristics under SPS modulation are analyzed, and the current-transfer equation is derived. A conversion coefficient is then introduced to transform the conventional phase-shift ratio into a new variable. Based on this, the time-domain characteristics of the inductor current peak and the constraints for zero voltage switching (ZVS) are analyzed. An analytical expression of the conversion coefficient is obtained, which ensures ZVS operation for all switches in the dual-active-bridge (DAB) converter and minimizes the inductor current peak. Finally, experiments verify the effectiveness and feasibility of the proposed modulation strategy.