一种适用于充电桩的LLC谐振变换器的PFM控制电路

A PFM Control Scheme for LLC Resonant Converter Applied to Charging Pile

为了减小充电桩的体积,提高装置的功率密度,设计了一种LLC谐振变换器的PFM控制电路,通过基波近似分析法对LLC谐振变换的参数进行了计算,对主电路伯德图进行了校正,并设计了补偿器,最后用PSIM软件仿真了相应的电路.结果表明:设计电路获得了原边开关管的零电压开通和副边整流二极管的零点流关断,大幅提高了开关管的开关频率并减小了开关损耗.

For the purpose of minimizing the power electronics devices and improving the power density,the switching frequency must be improved. A PFM control circuit for LLC resonant converter is designed. Just with many advantages comparing to Series Resonator and Parallel Resonator,the LLC resonator is used widely. The equivalent circuit model of the converter was obtained by fundamental analysis. And corrected the Bode diagram,designed the compensator. Used the PSIM software simulated the circuits,it showed that the LLC resonant can achieve the primary switch Zero Voltage Switch turning on and secondary rectifier diode Zero Current Switch turning off. Improved the switching frequency and minimized the switching loss. The LLC resonator＇s frequency can attain 200 k Hz and the output voltage and current is 200 V/25 A.