Experimental Study on Asymmetric Wireless Power Transfer System for Electric Vehicle Considering Ferrous Chassis

Steel chassis of an electric vehicle (EV) could reduce the efficiency of a wireless power transfer (WPT) system installed on which. To improve the performance of practical EV-oriented wireless charging systems, asymmetric WPT systems in ferrous environment are studied in this paper. First, inevitable adverse effects of the ferrous chassis on a nearby WPT coil are investigated. Then, impedance matching criteria to achieve the theoretical maximal efficiency of a general WPT system are theoretically elaborated. Further, one common symmetric and two asymmetric EV oriented WPT systems are built and comparative experiments on these three WPT systems are conducted. Vulnerability to ferrous environment, throughput power, efficiency, misalignment sensibility, as well as electromagnetic field radiation of these three WPT systems are assessed and compared in both ideal environment and chassis-emulated ferrous environment. Experimental results indicate that, asymmetric WPT system with a smaller transmitter and a larger receiver is more suitable to be implemented on a real EV for wireless charging.