Composite magnetic materials development for application in inroad charging systems

Abstract

In-road inductive power transfer (IPT) charging systems that can couple power across an air gap without any physical contact, will make EVs easier to charge. Current IPT systems typically use solid ferrite materials to improve magnetic coupling. Although ferrite is good for guiding magnetic fields, it is very brittle and a large solid block of ferrite would not survive within a road’s structure. Strong robust magnetic materials are required so that vehicles can run over charging pads built into the road without destroying them. This will require innovative affordable solutions and new magnetic material sources to meet these needs in an economically viable way.This study reports on investigations using soft magnetic composite (SMC) materials made with a range of magnetic powders and binder materials. Manufacturing methods were developed based on magnetic ferrite powders to maximise both magnetic and mechanical performance of SMCs. The best performing SMC sample was achieved with 81 vol% magnetic loading with a polyurethane binder. It had a magnetic permeability of μr = 80 and a failure strain (ductility) 20× that of ferrite which is superior to similar types of commercial SMCs currently available for inroad charging applications. The methods and understandings developed in this study will guide future development and performance enhancement of SMCs for inroad charging.