Thermal behavior analysis of wireless electric vehicle charging system under various misalignment conditions

Concerning thermal safety, the surface of ground assembly (GA) is deemed as the most critical part of wireless charging device for electric vehicles (EVs). As a result of accumulated losses in the charging process, its temperature gradually climbs, which may lead to dermal injury to children and ignition of combustible debris. In practice, it is very usual that the GA and vehicle assembly (VA) are not perfectly aligned, wherein its temperature rise will be even higher as a penalty of efficiency deterioration. However, it rarely attracts attention as a safety hazard. This article is devoted to risk evaluation of the GA surface. The temperature-rise-related losses are derived. The thermal distribution is simulated in a transient-state way by JMAG. On the basis of IEC specification, a four-temperature level framework is established as evaluation criteria. The results signify severe impact of GA-VA misalignment on the thermal performance. Moreover, sensitivity analysis of three kinds of misalignments to the temperature rise is conducted. When the horizontal misalignment is larger than 81.12 mm or the angular counterpart exceeds 6.83 degree, the highest hazard level will be reached, revealing over-temperature risk.