A Mode-Switching-Based Phase Shift Control for Optimized Efficiency and Wide ZVS Operations in Wireless Power Transfer Systems

This article proposes a mode-switching-based phase shift control (MS-PSC) for wireless power transfer (WPT) systems, which is able to achieve power regulation, load matching, and wide ZVS operations simultaneously without using additional dc-dc converters. Based on the mode transitions between the full-bridge, mixed-bridge, and half-bridge modes of both the inverter and the rectifier, the MS-PSC method guarantees a wide-range ZVS with minimized circulation of reactive power. Therefore, the system efficiency is improved over a wider power range compared to the conventional triple-phase-shift (TPS) control and the existing hybrid modulation control. The principles of different operating modes are analyzed. Then, the implementation of the proposed MS-PSC method and the mode selection strategy are presented. Finally, the effectiveness of the proposed MS-PSC method is validated in a WPT prototype. Experimental results show that the proposed MS-PSC method can achieve a high overall efficiency in a wide power range. Compared with the conventional TPS control, the MS-PSC method further optimizes the efficiency in 10%-63% of the rated power, with efficiency improvements ranging from 1.5% to 6%. As a result, the system efficiency remains at 93.5%-96.1% in the power range of 1-10 kW, with the transformer coupling coefficient k = 0.19.

Automated summary

This article proposes a mode-switching-based phase shift control (MS-PSC) method for wireless power transfer (WPT) systems. The method enables power regulation, load matching, and wide zero voltage switching (ZVS) operations without additional dc-dc converters. By analyzing the mode transitions and implementing the MS-PSC method, the system efficiency is improved over a wider power range compared to conventional controls. Experimental results validate the effectiveness of the proposed method, achieving high overall efficiency and further optimizing efficiency in a certain power range.