An Integrated DC-DC Topology Combining Wireless Power Transfer and CLLC Resonant Converter for Electric Vehicle Charging

In conventional electric vehicles, the on-board charger and wireless power transfer operate as two separate charging systems, which can lead to redundancy and increased costs. To enhance the integration of electric vehicle (EV) battery charging systems, this paper proposes a novel DC-DC topology integrating a wireless power transfer (WPT) and a CLLC resonant converter. By sharing the receiver coil, compensation capacitor and full-bridge rectifier between the two subsystems, the proposed design achieves high power density while significantly reducing the system cost. Instead of a transformer in the CLLC converter, a strong coupling mechanism is used, and the secondary coil of the strong coupling mechanism can be loosely coupled to the transmitter coil of the WPT system and used as the receiver coil. The integrated DC-DC topology has a large difference in leakage inductance between the receiver coil in CLLC mode and WPT mode due to the difference in coupling coefficients, which requires compensation capacitors with different capacitance values, so switched capacitor regulation of capacitance values is proposed to achieve the optimal operation of WPT and CLLC systems. This paper describes the integrated DC-DC topology, the operating principles in different modes, and the design of a novel integrated magnetic coupling mechanism, and finally verifies its feasibility through experiments.