A Fast and General Method to Calculate Mutual Inductance for EV Dynamic Wireless Charging System

For the electric vehicle (EV) dynamic wireless charging system, mutual inductance is an important factor affecting the output power. In this article, a fast and general method to calculate mutual inductance is proposed. This method can calculate the mutual inductance of magnetic couplers with different receiver structures and receiver positons by only one simulation, and it can also provide a theoretical guidance for the receiver design. Calculation models for different receiver structures are established, and the mutual inductance calculation-coefficients are proposed to describe the functional relationships between mutual inductance and receiver's parameters. Based on the concept of mutual inductance calculation-coefficients, the surface-integral in the conventional analytical calculation method can be simplified to be the product of these coefficients and magnetic flux density's amplitude, and then the calculation difficulty of the mutual inductance can be reduced. Finally, a prototype was built for experimental verification. The experiment results show that the max error between the measured mutual inductance and the calculated result is only 1.56%, which verifies the feasibility and the accuracy of the proposed calculation method.