Research on Bidirectional Isolated Charging System Based on Resonant Converter

Abstract

This paper proposes a two-stage bidirectional isolated charging system, which can realize the bidirectional flow of electric energy, not only making the electric energy flow from the grid side to the battery side but also converting the battery’s energy into single-phase alternating current to supply other electric equipment. The charging system also has the function of power factor correction and wide-range voltage output. The front stage of the charging system is a bidirectional totem pole structure power factor correction converter with a voltage and current double closed-loop control strategy to ensure the stability of the DC bus voltage, and the rear stage is a bidirectional CLLLC resonant converter, which adopts a high-frequency soft start strategy to reduce the inrush current during start-up and ensure the safe operation of the converter. Moreover, the frequency control strategy is used to make it have a wide range of DC output characteristics. In this paper, the principle analysis and parameter calculation of the charging system is carried out, the simulation platform and hardware circuit design are built, and a test prototype is piloted to verify the bidirectional operating characteristics of the charging system. The simulation and experimental results demonstrate the correctness of the theoretical analysis and topology design.