Precise Parameterized Modeling of Coil Inductance in Wireless Power Transfer Systems

To expedite the laborious design and optimization of resonant coils in wireless power transfer systems, many traditional modeling methods are studied to calculate the coil inductances based on simplified coil structures. However, coil layouts are oversimplified in these studies, especially ignoring the corners of rectangular coils, thus leading to unavoidable low calculation accuracies. Aiming at these issues, precise parametric structure models are proposed for the circular and rectangular coils, which particularly model the corners of rectangular coils as elliptic arcs for the first time. Moreover, based on the parameterized coil structures, precise parametric inductance models are developed to achieve accurate and fast inductance calculations for coils with and without ferrite plates. Particularly, the complex mutual inductances between elliptic corners and other sections in rectangular coils are precisely analyzed and modeled. Through extensive theoretical calculations and experimental verifications, the proposed parametric inductance models not only exhibit higher calculation accuracies than traditional methods but also demonstrate much faster calculation speeds than finite element method (FEM) simulations. Specifically, the proposed models for circular and rectangular coils can enhance the mean accuracy in inductance calculation by more than 13% than traditional methods. Moreover, the proposed model implemented with MATLAB and Python programs is about 3 and 6 times faster than FEM simulations, respectively.