宽输出三电平LLC谐振变换器及控制策略OA

With the massive growth of the electric vehicle(EV)market,the applications of EV charging equipment have also increased.Aimed at the disadvantages of traditional EV charging converters such as a small voltage-gain range,a low efficiency in low voltage output mode and a high voltage stress in rectifier diodes on the secondary side,the topology of a three-level LLC resonant converter with integrated flying-capacitor cell is improved,and a Burst control strategy with variable pulse width is proposed to enhance the efficiency in low voltage output mode.Through the hybrid control composed of pulse frequency modulation and the proposed Burst control strategy with variable pulse width,a wide output voltage is achieved,and the voltage-gain range under the Burst control strategy with variable pulse width is analyzed using first harmonic approximation.Finally,an experimental prototype with maximum power of 2 000 W was built,and results verified the feasibility of the novel topology of the improved three-level LLC resonant converter with integrated flying-capacitor cell and its Burst control strategy with variable pulse width.