Synthesis of the mutual inductor of a Wireless Power Transfer Systems: a field-circuit approach

Wireless power transfer systems are a viable solution to solve the problems that still delay a widespread diffusion of electric vehicles. Performances of these systems are affected by the magnetic characteristic of the coupling coils, so that they should be carefully designed. This paper presents a two-stage process for the optimal design of the coils. In the first stage, the equivalent circuit of the coupled coils is synthesized using an analytical approach for the computation of the objective functions and a genetic algorithm for their minimization. In turn, in the second stage, the optimization acts on objective functions computed by FEM analysis and identifies the geometrical parameters of the coils with the aim of achieving the circuit parameters recognized as optimal at the end of the first stage. The effectiveness of the proposed method is checked comparing the obtained coil design with a laboratory prototype.