Analysis on Pre-charging of Auxiliary Resonant Capacitor of Resonant DC Link Inverter

Based on the resonant DC link inverter with energy feedback function, in order to overcome the problem of voltage change rate (dv/dt) increase caused by the auxiliary resonant capacitor not being charged to the power supply voltage during its operation, this paper analyzes its pre-charging process in detail. When the energy stored in the auxiliary resonant inductor is not enough to charge the auxiliary resonant capacitor to the power supply voltage, the latter will not immediately participate in the resonance process, resulting in an increase in the voltage change rate at both ends of the bus and main switches. Under this condition, the working mode of this soft-switching inverter is given, and the parameters are designed to suppress the increase of voltage change rate. Finally, the correctness of theoretical analysis is proved by comparing the waveforms of switches under different resonance parameters.