A ZVS Critical Current Tracing Modulation for Current-Fed Series Resonant Converters in Fuel Cell Vehicles

In this letter, the redundant circulating current is identified as the key factor leading to the degradation of the efficiency of current-fed series resonant converters at light loads, which limits their performance in fuel cell vehicles. To tackle this issue, a zero-voltage switching (ZVS) critical current tracing modulation is proposed for the current-fed series resonant converter. In the proposed method, the circulating current is adjusted to trace the critical circulating current for ZVS, and the excessive loss caused by the redundant circulating current can be suppressed. Finally, a 1-kW prototype is built to verify the effectiveness of the proposed modulation, and a maximal efficiency increase of 15.1% at light load is achieved.