Critical Parameter Design and Power Quality Optimization of Two-Stage Isolated Inverter Power Supply Based on Series Resonance

In order to address the issues of low efficiency, large size, and low output power quality in the two-stage inverter power supply, this paper focuses on the series-resonant push-pull converter and conducts an in-depth analysis of its different operating modes. Two critical operating modes of the converter are identified, and optimal parameter designs for the resonant components under different critical operating modes are derived through time-domain analysis. The reasons and consequences of the double-frequency ripple voltage on the two-stage circuit bus are analyzed, and a modulation wave reconstruction nonlinear feedforward control strategy is proposed to real-time correct the modulation signal and reduce the impact of bus ripple voltage on the output power quality. Finally, simulation models and experimental platforms are built to validate the correctness of the theory. The experimental prototype is designed to operate in the second critical mode, and the results show that the proposed scheme can enhance the peak efficiency of the power supply by 5%, reduce the volume by 40%, and decrease the output voltage total harmonic distortion (THD) by 0.56%, effectively improving the efficiency and output power quality of the inverter power supply.