A Subdomain Analytical Model of Coil System with Magnetic Shields of Finite Dimensions and Finite Permeability for Wireless Power Transfer Systems

In the wireless power transfer (WPT) system, the magnetic shielding of finite permeability and finite dimensions is practically used with the primary and secondary coils. Generally, the analytical model is used to design such coils having magnetic shields. However, the reported analytical models in the literature include the magnetic shield with different assumptions, which introduces errors in the calculated results. In this context, this article presents a 3-D analytical model that does not consider such assumptions. This 3-D model is developed by the superposition of two 2-D analytical models. These 2-D models are developed based on the subdomain technique. Since 2-D models are invariant in their third direction (i.e., in the y -direction for the xz -plane and the x -direction for the yz -plane), a correction factor is introduced for 2-D subdomain models to make it variant in their third directions. The results obtained from the subdomain model are compared with finite element analysis (FEA) and experimental results, which are found in good agreement. The proposed subdomain model can be used in the initial design and optimization of the coils used in the WPT system.