Calculation of mutual inductance based on field-circuit coupling analysis for WPT

Determination of mutual inductance in the WPT system based on the electromagnetic coupling mode is crucial for system design and efficiency optimization. The analytic formulas and experimental methods which only aim at a coupling coil with a certain type of configuration and parameters are not universal approaches. Therefore they can´t serve as a design basis for the system optimization. This paper presents a novel calculating method based on field-circuit coupling. This method can process the different coil configurations and two coils with different spatial positions. It also allows the variation of magnetic medium during modeling. In this method, the mutual inductance parameter is processed by Matlab with the secondary open circuit voltage as the intermediate variable. Then, a mutual inductance function of axial distance, intersection angle, coil configuration and turn ratio is obtained. This function can be directly used to calculate the operation parameters and optimize the system efficiency in the power transmission system with electromagnetic coupling or resonant coupling. The method has made a breakthrough and provided a powerful tool for the design and optimization of electromagnetic coupling power transmission system.