High-power-factor operation of three-phase AC-to-DC resonant converter

Analysis and design of a three-phase AC-to-DC resonant converter is considered. The power factor of the three-phase AC input line diode bridge rectifier is improved by injecting high-frequency current. The three-phase AC-to-DC resonant converter is operated at frequencies above the resonant frequency. The analysis of the converter is carried out using different operating modes in one switching cycle of the resonant inverter. The design of the AC-to-DC resonant converter is discussed step by step. An experimental prototype of a 3 kW, 500 V output power and operating above 300 kHz has been developed in the laboratory. The proposed three-phase AC-to-DC resonant converter has high power factor, low total harmonic distortion and high efficiency. It requires narrow variation in switching frequency to regulate the output voltage.