A Novel High-Frequency Hybrid Resonant Converter for CC-CV Charger of 48V Urban-Electric Vehicles

In this paper, a novel hybrid resonant converter for a low voltage high current on-board charge system is proposed. Two transformers are employed with connected-series primary and parallel secondary, which reduces the step-down ratio of the transformer and current stress on secondary devices. Constant Current (CC) and Constant Voltage (CV) charging profile can be performed automatically by reconfiguring between a high order resonant network and a series LC resonant tank at the primary side without frequency or phase-shift modulation. Due to excellent soft switching and output regulation characteristics, the proposed converter design is suitable to operate at several-hundred kHz up to MHz switching frequencies. By adopting GaN-FETs and high-frequency planar transformers, the power density and efficiency of the proposed design can be further improved. In this article, operating principle and steady state analysis are presented. Additionally, simulation and experiment results are provided to validate the feasibility of proposed converter