Shielding Optimization of IPT System Based on Genetic Algorithm for Efficiency Promotion in EV Wireless Charging Applications

Abstract

For an inductive power transfer (IPT) system used in electric vehicle (EV) charging, the receiving coil is usually equipped with a shielding structure to reduce iron loss and electromagnetic interference in the chassis. However, the addition of a shielding structure may significantly reduce self-inductance and mutual inductance, and the eddy current on the shielding pad can also produce power loss. To maximize the efficiency of the IPT system used for EV charging and sufficient shielding, this study first analyzed the equivalent circuit model of the IPT system. A 3-D model of an IPT system, with a steel plate and aluminum shielding, is established and investigated in the finite-element analysis (FEA) domain, in which the shielding structure is modeled with some parametric sizes to simplify the modification of the parameters on a shielding structure. The simulation result shows how the ohmic loss on coils and the iron loss on steel plate changes after adding the shielding structure. Afterward, a practical method for optimizing aluminum shielding structure's parameters is proposed to maximize the efficiency of the IPT system, taking iron losses in a steel part and aluminum shielding into account. Furthermore, considering that the optimization procedure becomes complex since the different resonant capacitances are required due to the variable inductances, a new efficiency calculation method by FEA is presented to simplify the optimization procedure. Experimental validation is finally performed on a 3-kW wireless charging prototype; thus, the effectiveness of the proposed method is verified.