High-Speed Electric Machines: Challenges and Design Considerations

High-speed electric machines (HSEMs) have been widely used in many of today's applications and are gaining more attention in the automotive industry. However, many special design challenges exist for HSEMs. This paper aims to summarize and discuss major challenges and design considerations for HSEMs. Solutions to overcome these challenges are also offered in this paper. Four major loss components of HSEMs are discussed and the methods to reduce each loss component are further explained. Bearing options for HSEMs are also compared. In addition, the rotor dynamics and structural challenges are discussed in detail, followed by some design suggestions and considerations. Thermal and cooling challenges are presented as an overview. At the end, the challenges for power electronics circuitry are also demonstrated and are followed by some proposed solutions. Thus, this paper offers a guideline for proper technique selection and the design of HSEMs and associated accessories.