Mutual Inductance Calculation of Circular Coils for an Arbitrary Position With Electromagnetic Shielding in Wireless Power Transfer Systems
Xueyi Zhang, Changhui Quan, Zhongqi Li
Abstract
Mutual inductance is a key parameter in a wireless power transfer (WPT) system that determines transmission power and transmission efficiency. Mutual inductance can be increased, and magnetic leakage can be reduced by adding electromagnetic (EM) shielding materials to the coil structure. However, the calculation of the mutual inductance between two arbitrarily positioned circular coils, including the effect of EM shielding, has not been resolved. In this article, an analytical formula for calculating the mutual inductance between two circular coils with arbitrary relative positions on a double-layer EM shielding is obtained based on the coordinate transformation method and electric field intensity. A series of experiments are carried out to validate the analytic calculations. The experimental results for each of the misalignment cases are compared with analytical predictions and finite-element method (FEM) solutions. The theoretical results and FEM simulation results are in good agreement with the experimental data, which verifies the validity of the proposed method.