Reconfigurable Receiver Wireless Charger Enabling Dual-Voltage Battery Charging With Reduced Component Voltage Stress

Abstract

Most modern electric vehicles use 400 or 800 V battery packs, posing challenges for wireless chargers that achieve peak efficiency at fixed load points defined by battery voltage and power demand. Conventional approaches for dual-voltage charging rely on additional DC–DC converters or the use of dual decoupled coil sets with multiple converters, thereby resulting in increased system complexity and reduced efficiency. To overcome these limitations, this article proposes a tapped-receiver wireless charging system with split-series compensation to charge 400 and 800 V batteries at the same power level. A passive single-pole double-throw switch reconfigures the same coil with appropriate compensation for dual voltage levels. A complete analytical design methodology based on load quality factor constraints is presented and validated through finite-element simulations in ANSYS Maxwell. System-level performance at 7.2 kW is verified using the MATLAB and LTspice simulation platforms. Experimental results obtained from a scale-down prototype of 1 kW operating at 100 and 200 V demonstrate peak DC–DC efficiencies of 94.68% and 92.36%, respectively. In addition, a home-based low-power charging mode is introduced for 400 V batteries (validated at 100 V, 350 W, with 93.1% efficiency) to enhance user convenience and utilize the unused coil turns. Owing to the substantial reduction in the transmitter coil inductance, the proposed approach reduces the voltage stress by approximately 86% and 80% across the contactors, and by up to 67% across the primary coil and the compensating capacitor, compared to the recently proposed tapped transmitter system. Further, comparison with recent dual voltage approaches shows that the proposed approach achieves comparable efficiency with fewer components.