Interoperability of the Voltage/Current Doubler Converter Employing Bipolar Pads with the SAE J2954 VA WPT2/Z2 for EV Wireless Charging

This paper investigates the interoperability of the proposed voltage/current doubler (V/I-D) converter used for wireless charging of electric vehicles (EVs), which achieves high efficiency when charging both 400V and 800V batteries at the same power. Nominally, the V/I-D converter employs bipolar pads (BPP) at both the primary and the secondary circuits. In this study, the functionality of the converter is assessed when the primary BPP is coupled with a standard secondary coil, here being the VA test station WPT2/Z2 from SAE J2954. First, the intended operation of the V/I- D converter is explained. After that, the equivalent circuit of the BPP primary coupled with the standardized secondary coil is modeled analytically. The operation based on the misalignment is discussed. Then, the interoperability is verified through experimental results for the entire constant current charging mode for a rated output power of 7.2kW. Even though the functionality of the V/I-D converter is not optimal during the interoperability, the measured DC-to-DC power transfer efficiency in the considered operating range reaches the maximum at 95.22%, while the minimum is 92.86%.