Impedance Shaping Control Strategy for Wireless Power Transfer System Based on Dynamic Small-Signal Analysis

The interaction between the resonant wireless power transfer (WPT) component and the dc/dc converter may weaken the system stability, causing overshoot and oscillation in the dynamic process of such WPT system. Nevertheless, both the mechanism and the solutions of the above problems are not fully researched for the WPT systems. This paper first analyzes the small-signal impedance characteristics of such systems and points out the cause of the instability phenomenon. Then, a novel control strategy is proposed to regulate the system impedance characteristics, which can suppress the interaction and improve the system dynamic performance. Small-signal analysis and experiment results demonstrate that the proposed strategy has the advantages of fast response and less overshoot compared with traditional PI control, and is suitable for different operating conditions.