Hybrid Core Composed of Ferrite and Nanocrystalline Alloy of Wireless Charging System for Electric Vehicle Application

Nanocrystalline and ferrite are two commonly used magnetic cores for magnetic couplers of wireless charging systems (WCSs) in electric vehicle (EV) applications. Considering the advantages and limitations such as loss, saturation, temperature, and weight of those two types of magnetic cores, a hybrid core, with nanocrystalline and ferrite on receiving and transmitting sides respectively, is proposed in this study. Firstly, different topologies are generalized into the form of S-S topology, and the influence of load and magnetic material on the efficiency of the magnetic coupler is analyzed for an S-S compensated WCS. Then, an evaluation method of magnetic materials in WCS is proposed according to the derived optimal load. Based on the simulation comparison and consideration for practical applications, the layout of the proposed hybrid core is proposed. With the genetic algorithm, a detailed design process is given and a design scheme is also obtained. Finally, a prototype with the proposed hybrid core is manufactured for experimental validation. The results show that the efficiency of the magnetic coupler with the proposed hybrid core can reach 95.395% at 20 kHz, which is 2.5% higher and only slightly lower than that of the coreless magnetic coupler and magnetic coupler with ferrite core, respectively.