Electric motors using non-heavy and non-rare earth permanent magnets

Most motors used in electric vehicles are based on high performance heavy rare earth (HRE) permanent magnets.  Elimination of heavy rare earth and all rare earth materials from permanent magnets  leads to a reduction in their performance – in terms of energy product, temperature stability, and can also make them prone to demagnetization.  Therefore, fundamental changes in the motor design process may be required to make the performance of non-heavy or non-rare earth magnet motors comparable to that of HRE magnet motors. 

This talk will discuss these design changes.  A high-speed motor using non-heavy rare earth permanent was designed, prototyped and tested at ORNL. The talk will discuss the motor design, cooling and other aspects that were taken into account to compensate for the poorer thermal stability of non-heavy rare earth permanent magnets.

In addition, the talk will compare the designs of motors based on  NdFeB, iron nitride and ferrite permanent magnet motors for a typical passenger electric vehicle application in terms of motor topology choices, rotor and winding geometry and possible cooling solutions. The motor performance  - including  power density and loss will be compared for each type of machine.

The talk will conclude with a discussion of emerging technologies that can enable high performance motors based on rare earth free permanent magnets.