Abstract：A novel L-LLC resonant bidirectional DC-DC converter (L-LLC-BDC) 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, a three pulses burst mode control strategy is proposed to improve the light load efficiency by optimizing the pulse width in a fixed burst on time. Based on the precise time domain analysis, the first pulse width in the burst on time stage is accurately predicted to make the converter reach the steady-state maximum efficiency point in the shortest time. Then, the next two pulses work at the resonant frequency point. The burst off time is changed to adopt to the load change in the burst mode. This three 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. A 760V/380V/6kW experimental prototype is built, the experimental results verify the correctness and effectiveness of the proposed three pulses burst mode control strategy.
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2022, Vol. 37 
