Phase Shift WPT System Integrated With Dual-Side LC Branches to Maintain High Efficiency Within Wide-Range ZVS Operation

The realization of zero-voltage switching (ZVS) plays a crucial role in improving the system electromagnetic compatibility (EMC), so wide-range ZVS operation is necessary for electric vehicles (EVs) wireless power transfer (WPT) system. However, to realize wide-range ZVS, the system impedance needs to be adjusted by the design of topology parameters and control strategies, which introduces large reactive current at light and medium loads, thus resulting in system efficiency degradation. To fill this gap, this article presents a novel WPT converter integrated with dual-side LC branches that helps realize ZVS while significantly reducing the rms current on switches, thereby minimizing the system conduction loss. Moreover, based on the mathematical model for the proposed system, a universal design method for LC branches and a combined modulation strategy are proposed to ensure the full operating range of ZVS and maintain high efficiency. Finally, a 3.3-kW experimental prototype is built to verify the proposed system and make a comparison with traditional phase shift (PS) WPT systems. The measured efficiency is over 91.7% from 12% to 100% loads with a maximum efficiency improvement of up to 6.47% at the light load.