Eddy Current Reduction in Automotive Permanent Magnets

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The movement to electrification of the automotive industry provides a huge opportunity to reduce the environmental impact of transport, and help meet UK and international climate targets, but it also presents technical challenges of the same scale. The core of each electric car, van or lorry is an electric machine. Although designs can differ, the vast majority use neodymium-iron-boron permanent magnets as a key component. When the electric machine operates, the high frequency magnetic fields produced cause eddy current losses in the magnets. This not only harms efficiency but can lead to localised heating reducing the magnet performance. While magnet materials have a generally higher resistivity than conductors, they do carry current, thus an increase in their resistivity would reduce eddy current losses and increase the efficiency of electric machines, improving vehicle performance. This project will explore approaches to achieving this, and the impact it would have in real applications. The processing of neodymium-iron-boron magnets will be explored using powder manufacturing methods, such as Spark Plasma Sintering (SPS, also known as Field Assisted Sintering Technology or FAST), with the incorporation of additional phases or pre-treatment of the powder to introduce more electrically resistive features to impede current flow. Samples will be evaluated to understand their structure, including the grain alignment, and the electric and magnetic performance. In parallel, finite element simulations of the material and how they behave in situ will be used to evaluate the impact of the different treatments on the motors efficiency.