Voltage and Rectification Timing Control for Start-Up Current Overshoot Suppression in Dynamic Wireless Power Transfer Systems

In dynamic wireless power transfer (DWPT) systems for electric vehicles, maximizing the power output from each transmitter (Tx) coil is essential for minimizing installation costs. However, in series-series (SS) type DWPT systems, applying a large step voltage in low-coupling regions causes a Tx-side current overshoot, which consequently requires increased equipment capacity. This study proposes a control method that simultaneously minimizes the current overshoot and settling time by combining bilateral voltage control with receiver (Rx)-side rectifier timing control, employing an active rectifier. The conventional current envelope model is extended to an SS-type DWPT system by approximating the time variation of mutual inductance using a polynomial. It is theoretically shown that voltage trajectories that eliminate oscillatory components while maintaining a constant steady-state current exist, and these trajectories are implemented through voltage control on both the Tx and Rx sides, along with Rx-side rectification timing control. The proposed method was experimentally validated on an 8kW-scale DWPT test bench operating at 20km/h. The results confirm that the proposed method reduces the Tx current overshoot from 207% to 5% and shortens the settling time to 0.14 ms. Consequently, under a 50A current limit, the received energy increased from 22.47 J to 115.8 J.