Push-Pull Zero-Voltage Switching Resonant DC-DC Converter Based on Half Bridge Class-DE Rectifier

This paper presents an analysis of parasitic capacitances in resonant rectifier which has significant impact on the operating point of the resonance circuit, which the junction capacitance is to decrease the resonant current and DC output voltage in the circuit at switching frequency less than resonant frequency. This can be represented by simplified series resonant equivalent circuit and voltage transfer function versus normalized operating frequency at varied values of resonant capacitor. The step-up resonant push-pull DC-DC converter was used as design example. The design procedure is based on the principle of the half bridge class-DE resonant rectifier. All power switches are operated under the zero-voltage switching conditions, resulting in higher overall system efficiency. The prototype of resonant DC-DC converter was operated at 62-88 kHz variable frequency, the input voltage of 12-V-DC, the output voltage of 380-V-DC and the output power rated of 150 W. The experimental results have shown that 92.97% efficiency at full power. The experimental results are presented to verify the theoretical analysis.