Research on rare earth electrolytic power supply based on three-phase LLC resonant converter

At present, China’s rare earth electrolytic power supply has the shortcomings of large volume and low efficiency, aiming at the occasion of low voltage and high current of rare earth electrolytic power supply, a three-phase LLC resonant converter with a pre-stage of three-phase PFC correction circuit and a post-stage staggered parallel structure is proposed, and the secondary side adopts a three-phase full-bridge rectifier circuit, and the resonant element adopts a triangular connection mode, which can effectively improve the power factor, reduce the harmonic distortion rate of the grid current, and reduce the current ripple. Then, the fundamental sinusoidal variable in the three-symmetric stationary coordinate system is transformed into the DC variable in the synchronous rotating coordinate system through the coordinate rotation transformation, and finally the fundamental approximation method (FHA) is used to analyze the gain of the converter. Through simulation experiments, it is verified that the structure can realize soft switching, and stably output 12 V DC voltage and 7000 A DC current, which meets the occasion of low voltage and high current of rare earth electrolytic power supply.