A Novel Frequency Modulation Technique to Minimize the Start-Up Transients in Dynamic Wireless Charging Systems for Electric Vehicles

In the dynamic wireless charging systems for Electric Vehicles (EVs), it is essential to minimize the startup transients, i.e., ensure low settling times and overshoot for the transmitter and receiver coil currents. In a dynamic charging application, the EVs have only short time intervals for charging. Hence, a faster settling is desirable so that enough charging time is available. Also, current overshoots should be minimized to reduce the excessive stress on the power devices and compensation elements. Therefore, soft-starting techniques are used to minimize the start-up transients. Conventionally, a phase-shift pulse width modulation technique is used for soft-starting. This work proposes a novel frequency modulation soft-starting technique that offers better start-up transient minimization than the conventional technique. Two other variations of the proposed frequency modulation technique are also presented and compared. The best frequency modulation technique for minimizing the start-up transients is identified. The popularly used series-series compensated wireless charging system feeding a constant voltage type load is considered here for the analysis. The simulations are performed in PLECS for a 7.7kW dynamic wireless charging system to demonstrate the performance of the soft-starting techniques. Experiments are underway to validate the claims and will be presented in a future paper.