A Novel Phase-Shift Pulsewidth Modulation Method for Light-Load Bidirectional Resonant Converter

For the bidirectional full-bridge CLLC resonant converter, soft switching of primary side and secondary side switches and bidirectional power transmission are its obvious advantages. However, in the pulse frequency modulation control under light-load conditions, the converter will have the disadvantages of output voltage imbalance and low transmission efficiency. In order to improve the range of voltage regulation and efficiency of CLLC resonant converter under light-load conditions, a novel phase-shift pulsewidth modulation method is proposed in this article. There is low voltage gain regulation and low operation losses can be achieved under light load. Considering the parasitic parameters and dead time of the switches, the voltage gain of the proposed control method under light load is precise research by using the time domain analysis method. Finally, an experimental prototype of a bidirectional full-bridge CLLC resonant converter with 200 V input voltage, 200 V output voltage, and a rated power of 800 W is designed. According to the simulation and experimental results, it can be shown that the proposed control method is effective under light-load operation.