Optimal PWM Frequency Acquisition Method Based on Parallel Structure of IGBT and WBG Inverter

In the parallel structure of IGBT and SiC MOSFET inverter, the PWM frequency of SiC MOSFET has a large adjustment range. If it is not properly designed, it will bring the problem of output instability. Aiming at this problem, a method is proposed to relate the switching frequency and the size of passive components, and then establish the relationship between the switching frequency and the system stability through impedance modeling. At the same time, the influence of the switching frequency on the dynamic performance of the system is considered. Finally, the accuracy of modeling and stability analysis and the validity of optimal switching frequency are verified by simulation. The method solves the problem of selecting the PWM frequency of the SiC MOSFET in the inverter with the hybrid parallel structure of the IGBT and the SiC MOSFET. It achieves the goal that the system is still stable when the PWM frequency of the SiC MOSFET is changed in the optimal frequency range.