Eddy Current Reduction in Automotive Permanent Magnets

汽车行业的电气化运动为减少运输对环境的影响提供了巨大的机会，并有助于实现英国和国际气候目标，但它也带来了同样规模的技术挑战。每辆电动汽车、货车或卡车的核心都是一台电机。虽然设计可能不同，但绝大多数使用钕铁硼永磁体作为关键部件。当电机运行时，所产生的高频磁场在磁体中引起涡流损耗。这不仅损害效率，而且可能导致局部加热，降低磁体性能。虽然磁体材料通常具有比导体更高的电阻率，但它们确实携带电流，因此它们的电阻率的增加将减少涡流损耗并增加电机的效率，从而改善车辆性能。本项目将探讨实现这一目标的方法，以及它在真实的应用中的影响。钕铁硼磁体的加工将使用粉末制造方法进行探索，例如火花等离子体烧结（SPS，也称为场辅助烧结技术或FAST），并结合额外的相或粉末的预处理，以引入更多的电阻特征来阻止电流流动。将对样品进行评估，以了解其结构，包括晶粒排列以及电磁性能。与此同时，材料的有限元模拟及其在原位的表现将用于评估不同处理对电机效率的影响。

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.