Improved hybrid control LLC resonant converter for electric vehicle charging

For on-board chargers, it is difficult for the traditional inverter-controlled LLC resonant converter to achieve a wide-range voltage output, and it is not conducive to the optimal design of the resonant converter. In order to solve these problems, an improved control method combining pulse frequency modulation (PFM) and phase-shift pulse modulation (PS-PWM) is proposed, which adopts phase-shift control in the case of low voltage and low power, and adopts frequency control for high voltage and high power, effectively broadening the output range of the LLC. Compared with the traditional variable frequency control, the improved hybrid control resonant converter has the following advantages: wide voltage range, narrow frequency and low circulating current loss. Finally, the validity and feasibility of the converter design and control strategy are verified by simulation.