Thermal Design and Evaluation of a Rectifier for Electric Vehicle Wireless Charging Using Hybrid PCBs and Planar Magnetics

Wireless power transfer (WPT) is expected to provide more flexibility and convenience in the electric vehicle (EV) charging process than conventional physical connector or cable-based conductive charging. However, the space limitation when integrating WPT into the vehicle underbody creates challenges in the design and installation of the system. Especially when integrating WPT into plug-in hybrid EVs (PHEVs), the design complexity increases significantly due to thermal issues caused by exhaust pipes and tighter packaging. In this article, we propose a novel rectifier design for the PHEV WPT receiver that decouples inductance and power sections using a separate multilayer FR-4 printed circuit board (PCB) and metal core PCB (MCPCB), respectively. In addition to this hybrid PCB design, the proposed strategy utilizes distributed planar PCB winding inductors to further reduce package size by 66% in height while improving the thermally safe clearance by over 20 cm. A detailed finite element numerical analysis reveals a maximum temperature reduction of 64.8% with a power transfer level of 7.2 kW when compared to a conventional design without incorporating the proposed design elements. Benefiting from enhanced heat spreading in the design, no additional passive cooling components are required in the proposed configuration while potentially maintaining the peak temperature under the permissible operating limitation of 125 °C. Low-power thermal experiments validate the numerical results with a maximum 2.1 °C deviation between the experiments and the simulations of the conventional and proposed strategies.