Eliminating Dead Zone in Wireless Power Transfer with Repeater Coil by Power Factor Control

Dynamic wireless power transfer (D-WPT) is attracting attention as a way to compensate for the shortcomings of electric vehicles. However, the cost of inverters for D-WPT is high due to the cost of the semiconductor devices and controllers, making it difficult to implement in society. Therefore, a method that can energize multiple repeater coils with a power transmitter coil is known as an effort to reduce costs. However, the repeater coil creates a dead zone in which the power cannot be transferred to the receiver coil. The main cause of the dead zone is the high input impedance of the circuit. This paper proposes a method to eliminate the dead zone by implementing power factor control on the transmitter side. In the proposed method, the frequency of the inverter is controlled to maintain the power factor to one when the receiver coil moves over the transmitter and repeater coil. The frequency of the inverter is determined by the hill climbing algorithm.