Design Method Of Cooling Structure Considering Load Fluctuation Of High-Power Wireless Power Transfer System

This paper proposes a thermal design method for transmission coils with thermally conductive plastic plates considering load fluctuation of high-power wireless power transfer (WPT) systems. The high power transmission may cause melting of an insulation coating film of litz wires due to the heat generation of the windings and cores. For this reason, a cooling structure for the transmission coils is required. As the cooling structure, thermally conductive plastic plates with high thermal conductivity and resistivity are inserted between the core and the aluminum plates for an improvement of heat transfer. By representing the cooling structure as a thermal equivalent circuit, it facilitates a thermal design that takes into account load fluctuations. The thermal equivalent circuit is composed of a two-stage ladder circuit divided into the WPT system part and a cooling part. The peak temperature and the maximum allowable loss of load fluctuation are derived by simplifying the two-stage ladder circuit. In addition, the thickness of the thermally conductive plastic plates is designed by the design flowchart for the 15- kW WPT system.