Electromagnetic Coupler in Wireless Charging for Electric Vehicles

Abstract

The transmission power in wireless charging for electric vehicles is unstable due to the decline of the coupling coefficient caused by the misalignment of the electromagnetic coupler.Considering misalignment tolerance and coupling coefficient, the paper designed a kind of asymmetric electromagnetic coupler with large lateral misalignment tolerance.The coupling coefficient of charging pads can be greatly improved by using the asymmetric structure, and the requirement of electromagnetic safety can still be met.The rectangular coil and the linearly-arranged ferrite strip along the long side ensure that the coupler has greater lateral misalignment tolerance, which solves the problem of not easy adjustment of lateral misalignment when electric vehicles park for wireless charging.The experimental results of transmission power with misalignment well agree with simulation results.Both simulation and experimental results show that the transmission power can keep stable within a wide offset range.In experiments, the transmission power of 2.1 kW at the interval of 125 mm has been realized, and the power variation within the offset of 100 mm is no more than 20%.