An Integrated WPT-APM System with Decoupled Charging for EV High-Voltage and Low-Voltage Batteries

Electric vehicles (EVs) typically have a high-voltage (HV) power battery and a low-voltage (LV) auxiliary battery. In traditional EV wireless power transfer (WPT) systems, the LV battery is charged from the HV battery via an additional auxiliary power module (APM), which leads to additional power losses and an undesirable reliance on the HV battery. To address these issues, this paper proposes an integrated WPT and APM system with a DC-link parallel AC-link series multi-inverter multi-rectifier architecture, enabling decoupled charging of both the HV and LV batteries without extra circuits or relays. At first, the proposed topology and circuit analysis are introduced. Then, three charging modes are discussed in detail, including simultaneous charging, HV battery charging, and LV battery charging. In addition, the design procedure is also summarized to provide a design reference for EV battery charging systems. Finally, a 5-kW experimental prototype is implemented, with 4 kW for the HV battery charging and 1 kW for the LV battery charging. The system achieves a maximum overall efficiency of 92.5%, while the efficiency degradation for LV battery charging is merely 3%, verifying its feasibility.