A High-Efficiency ZVS Wireless Power Transfer System for Electric Vehicle Charging WithVariable Angle Phase Shift Control

Tight current/voltage regulation and high efficiency are the fundamental objectives of wireless power transfer systems (WPTSs) for electric vehicle (EV) chargers. To achieve high efficiency and minimize electromagnetic interference, it is necessary to ensure zero-voltage switching (ZVS) of all MOSFET switches. However, such objectives often necessitate auxiliary dc-dc converters or additional resonant components, which increases system costs and complexity. In this article, a high-efficiency WPTS is implemented without any additional converter or resonant component. Only two H-bridge converters, i.e., an inverter and an active rectifier (AR), are employed. The AR utilizes the variable angle phase shift control (VAPSC) that achieves accurate current/voltage regulation and ZVS simultaneously. Moreover, the optimal power angle range (OPAR) is identified, within which the system efficiency is further enhanced through power loss analysis. Subsequently, the proposed WPTS is regulated via a noncommunication double-loop control strategy, which gets rid of communication interferences and noises. The maximum transfer efficiency can be obtained by adjusting the ZVS angle in OPAR. Finally, the experimental results obtained from a 500-W WPTS prototype verify the theoretical analysis. Under the case of a coupling coefficient k=0.2, the maximum transfer efficiency reaches 95.2% at rated power.