부산대학교 도서관

This brief discusses the operation and performance comparison of LCL-T DC-DC resonant power converter when controlled with fixed-frequency phase-shifted gating (PSG) and modified-gating signals (MGS) schemes. The converter is designed to operate in lagging power factor mode to accomplish zero-voltage switching (ZVS) of the inverter switches. The operating principle of the converter with the two proposed gating schemes is explained. A brief steady-state analysis of the converter using Fourier series approach is presented. The choice between PSG and MGS schemes is made by comparing the performance of the converter. It is found that both the gating schemes are effective in regulating the output voltage for variable input voltage and loading conditions. However, the efficiency of the converter is found to be higher with MGS due to the fact that only one switch loses ZVS as compared to two with the PSG when operated with maximum input voltage. Also, the variation in pulse-width angle ( ${\delta }$ ) required to regulate the output voltage is small in MGS as compared to that with PSG. A 300 W experimental prototype of the converter has been built and tested to verify the theoretical results. It is experimentally confirmed that the MGS control gives the better performance than the PSG control for different input voltage and loading conditions.