A 22 kW-85 kHz Three-phase Wireless Power Transfer System with 12 coils

Abstract

A 22-kW three-phase wireless power transfer (WPT) system with six primary coils and six secondary coils are proposed is developed in this paper. For the rapid charging of onboard batteries of electric vehicles (EVs), the output power of the WPT system should be increased. However, the increase of the WPT system may cause an increase in leakage magnetic flux. The leakage magnetic flux from the WPT system must comply with guidelines. The proposed WPT system with 12 solenoid coils, which are circularly placed, suppresses the leakage magnetic flux with two opposite solenoid coils which are differentially coupled. Moreover, the circularly placed coils cancel out the magnetic interference, which is caused by the coupling among the primary coils, and secondary coils. In this paper, first, the 22-kW three-phase WPT system is designed. Especially, the figure of coils, which achieves a minimum volume of the core, are determined with the cancellation capability of the magnetic interference. Then, the 22-kW WPT system is tested with a constant voltage load. The maximum efficiency of the proposed WPT system from a primary DC to a secondary DC side is 91.1% at an output power of 22 kW with a 400-V constant voltage load.