An Approach for Mutual Inductance Identification of Wireless Power Transfer System in Electric Vehicle Charging Applications

As a key parameter of fundamental electrical, mutual inductance always used to characterize the overall performance of wireless power transfer (WPT) system in electric vehicle charging applications. However, in real case, factors such as parking misalignments, load variations and intrusion of foreign objects would result in a variation of mutual inductance between both coils, which may adversely impact on transmitted power and transmission efficiency. Therefore, in this paper, we propose to identify mutual inductance parameter with the least square method (LSM) based on the equivalent circuit model. In section II, COMSOL is adopted to simulate mutual inductance variation with the change of lateral offset. In section III, the differential equation is derived from the state space equation of the WPT system. Through identifying the process parameters, the mutual inductance of coils can be obtained by the functional relationship between them. In section IV, by means with simulation used MATLAB/Simulink, we verified the feasibility of mutual inductance identification with LSM. Compared with the numerical value of COMSOL simulation, the MATLAB result shows that the identification accuracy of mutual inductance is within 5% which is an acceptable range.