Investigation of magnetic flux distribution of EV wireless charging systems

A High Frequency and High Power Density Wireless Planar Transformer (HFHPD-WPT) is a very attractive future technology which can provide power to an electric vehicle (EV) through a contactless charging system. In this paper, EMC computer modeling and simulation techniques are employed to investigate the magnetic flux distribution and associated EMC problems such as stray fluxes and hot spots. The bifilar planar spiral coils of the transformer are designed on multilayer PCB. A finite element method (FEM) has been used to calculate the magnetic field. The effect of the planar magnetic ferrite cores on magnetic flux distribution has been investigated by using three designs, where the first design has the ferrite core only at the primary side, the second draft has a planar core on the primary and secondary side, and the third design has a U-Shape magnetic core for the primary and secondary side. Both designs are operating at a resonant frequency of 60 kHz. A new proposed design is introduced to minimize flux leakages and reduce hot spots, in order to improve the flux distribution and to increase the magnetizing impedance.