A WPT System With Wide-Range Voltage Gains and Soft Switching via Primary-Side Hybrid Modulation

Wireless power transfer systems for electric vehicles require wide-range voltage gains to satisfy battery charging requirements and coupling coefficient variations. However, existing solutions typically require additional dc-dc converters, or may suffer from discontinuous output voltage and hard switching. To solve these problems, this article proposes a primary-side hybrid modulation method that can achieve wide-range voltage regulation and zero voltage switching (ZVS) simultaneously. At first, the topology of the proposed system and the hybrid modulation method based on variable frequency modulation are presented. Then, the design procedure of the system is described, and a parameter design method of the vehicle assembly is proposed to achieve ZVS and a wide range of operating frequencies. Meanwhile, the control scheme of this system is demonstrated in detail. Finally, a 5-kW prototype with a maximum efficiency of 93.2% is built and the feasibility and effectiveness of the system are verified.