Misalignment Tolerance of Inductive Power Transfer Coupler With Low Loss and High Magnetic Induction Ferromagnetic Materials

For an inductive power transfer (IPT) system, ferromagnetic materials such as ferrite and nanocrystalline are generally adopted to enhance the coupling and misalignment tolerance between the primary and secondary coils. However, it may decrease the transmission efficiency of IPT system due to the different magnetization and loss characteristics of ferromagnetic materials. Therefore, it is necessary to investigate material performance accurately under the real scenario of high frequency supply. In this study, a mathematical model of the IPT system is firstly established and a new test method combining 3-D finite element analysis (FEA) for magnetization and loss characteristics of ferromagnetic materials in IPT system is proposed and the loss variations of different ferromagnetic materials are also revealed. With the measured magnetization and loss data, misalignment tolerance of magnetic coupler with different ferromagnetic materials is investigated by 3-D FEA. It is found that, when the magnetic field conforms to the paramagnetism of the magnetic material, misalignment tolerance can be improved effectively and the higher efficiency of magnetic coupler can be reached under misalignment conditions. Experimental validation is performed on a 1.2-kW coupler prototype under 200-mm misalignment between primary and secondary coils. With the ferrite and nanocrystalline cores of horizontal and vertical laminations, efficiency of magnetic coupler decreases by 0.457%, 1.392% and 1.352%, respectively, and misalignment tolerance of coupler can be improved effectively.