A 50 kW Modular Wireless Power Transfer System with Low Stray Magnetic Field

Adopting high power wireless charging systems, particularly for heavy-duty electric vehicles (EVs) and fast charging of regular EVs becomes extremely imperative. The stringent requirements of safety guidelines, high efficiency, and high-power density would continue to impede the rapid penetrations of wireless power transfer (WPT) systems for EVs at high power. This paper investigates the potentials of multi-channel WPT systems to achieving high power transmission under these stringent requirements. A multi-channel WPT system consists of multiple power-transfer paths such that adjusting the number of channels affords the system become adaptive to multiple power levels. That could eventually present an opportunity for developing high power, which would be seriously challenging with conventional single-channel systems. Moreover, different channels can co-operate to achieve superior performance, such as low stray magnetic field. As an example, a three-channel WPT system is designed in this paper, and its capability of significantly reducing the stray magnetic field is investigated. By properly determining the power-sharing proportion of the channels, magnetic field reduction of 80% and 63% can be achieved compared with the rectangular-pad and DD pad systems (under similar total pads area), respectively. A three-channel 50 kW prototype is produced to verify the analysis.