Optimal Control Strategy of CLLC Bidirectional Resonant Converter under Light Load

CLLC resonant bidirectional DC-DC converter has characteristics of isolation and high efficiency. The burst mode under light load is an effective way to increase the light load efficiency. In this paper, pulses burst mode control strategy is proposed to improve the light load efficiency by optimizing the pulse width in a fixed burst on time. First, a modeling method of time domain analysis is adopted to obtain the accurate converter model, Then, the subsequent two pulses work at the resonant frequency point. The burst off time is adapted to the load change in the burst mode. This pulses burst mode control strategy does not need to measure the resonant capacitor voltage, simplifies the circuit, improves the efficiency of light load and minimizes the output voltage ripple. Simulation results verify the efficiency of the method.