Structure-Reconfigurable Wide Gain Series Resonant Converter for On-Board Charger

In this article, a structure-reconfigurable series resonant DC-DC converter is proposed for a wide gain on-board charger application. The proposed converter consists of a dual-bridge structure on the primary side which can realize 0.5 to 1 voltage gain by using a reconfigurable half/full bridge structure, and a hybrid rectifier on the secondary side which can realize 1 to infinite voltage gain by replacing two diodes with active switches. Moreover, the proposed converter employs a control scheme based on fixed frequency PWM, with the operating frequency being identical to the series resonant frequency. Accordingly, magnetizing inductance of the transformer is independent of the converter gain characteristics, which simplifies the consideration of the resonance parameters design. In addition, soft switching can be realized during the entire charging process, and high efficiency can be achieved. To avoid the voltage spike and current impact in the transition between two operation modes, a unified switching modulation strategy is applied to achieve a smooth transition and improve the control stability. Finally, a 2.5 kW prototype with an output voltage range of 200V - 500 V is established and tested to verify the effectiveness and feasibility of the proposed converter.