A Dynamic Charging System With Reduced Output Power Pulsation for Electric Vehicles

This paper proposes a continuous dynamic wireless power transfer system for electric vehicles that reduces power pulsations during the charging process. Multiple rectangular unipolar coils are used at the primary side as the transmitters, and another unipolar coil works as a receiver at the secondary side. The transmitters are placed closely together to reduce the variation of magnetic fields along the moving track of the receiver. This structure induces self-coupling between the adjacent transmitters. AnLCC-compensated circuit topology is utilized, and a compensation parameter design is provided which considers self-coupling between the primary coils. Finite-element analysis of the dynamic charging system is performed using Maxwell. The receiver size is optimized to reduce the variation of the coupling coefficient. A 1.4-kW dynamic charging prototype is constructed according to the designed coil structure and circuit parameters. There are six transmitters, each with dimensions 388 mmx400 mm, and one receiver with dimensions 485 mmx400 mm. Experimental results show that the output power pulsation is within +/- 7.5% in the dynamic charging process, and the maximum efficiency is 89.78%. If the edge effects of the transmitters are neglected, then the power pulsation is within +/- 2.9%.