Comprehensive Analysis of Nanocrystalline Ribbon Cores in High-Power-Density Wireless Power Transfer Pads for Electric Vehicles

The nanocrystalline alloys are gradually used as shielding materials in wireless power transfer (WPT) systems with the development of high power density. In this article, the system properties of WPT using ferrite and four types of nanocrystalline cores are simulated by 3-D finite element analysis (FEA). Based on this, a novel shielding pad composed of nanocrystalline alloy and ferrite is designed to improve the WPT system properties. The WPT systems are preliminarily compared with 3-D FEA when the different nanocrystalline alloys are used in the novel shielding pad. The experimental WPT system for 85 kHz and 1.5 kW with a 24 cm air gap between the primary and secondary coils is built to validate the simulation. The results show that significantly greater shielding can be realized for the novel pad at the price of a slight decrease of transmission efficiency than conventional ferrite core.