Transient control based on transmitter current envelope model for in-motion wireless power transfer

In-motion wireless power transfer (WPT) is expected to solve many problems of electric vehicles (EVs). In order to transfer a large amount of energy to vehicles running at high speed, quick-start charging is needed. However, the sudden starting of the power transmission causes a large current overshoot, which damages the equipment of the WPT system. Therefore, it is commonly thought that the transient property of current must be improved. However, a transient control method with an accurate circuit model for EV applications is yet to be developed. Here, we propose a novel control method using the envelope model of the transient response. We applied the precise envelope model with d-q conversion to the starting of the power transmission considering the different modes of diodes. By calculating the inversion of the circuit model, the input voltage trajectory that achieves the desired current trajectory was theoretically obtained. Finally, the proposed method enabled quick-start charging without causing any current overshoot. This method is expected to be an essential technique for the practical use of in-motion WPT.