A Wireless Powered EV battery charger for sinusoidal current charging technique with maximum efficiency control

This paper reports on implementation of sinusoidal battery charging technique for Wireless Power Transfer (WPT) with maximum efficiency control algorithm. In sinusoidal current charging technique, the battery current varies continuously depending on charging frequency and current. Therefore, to improve the overall efficiency of the system, load impedance has to be matched with source impedance continuously depending on charging current frequency. In this paper, an algorithm is presented to maximize the efficiency of the system. For concept A, algorithm varies both frequency and phase shift of the inverter output voltage to minimize input power, whereas output power is kept constant by a dc-dc converter. For concept B, the battery current is controlled by switching frequency, and the algorithm optimizes the phase shift of inverter to improve efficiency. To verify the proposed system, a brief mathematical analysis is provided. Further, a laboratory prototype of a 600W power rating is developed, and results are presented to verify the effectiveness of the concept.