A 50-kW Three-Channel Wireless Power Transfer System With Low Stray Magnetic Field

Abstract

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 article investigates the potentials of multichannel WPT systems to achieve high-power transmission under such requirements. A multichannel 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 the conventional single-channel systems. Moreover, different channels can cooperate to achieve superior performance, such as a low stray magnetic field. A three-channel WPT system is designed in this article, and its capability of significantly reducing the stray magnetic field is investigated. By properly determining the power-sharing proportion of the channels, the magnetic field reduction of 80% and 63% can be achieved compared with the rectangular-pad and double D (DD) pad systems (under similar total pads area), respectively. A three-channel 50-kW prototype is produced with a dc-dc efficiency of 95.2% across the 160 mm air gap. The measured results of the magnetic field agree well with the simulation ones.