High-speed permanent magnet electrical machines — applications, key issues and challenges

In this paper, application examples of high-speed electrical machines are presented, and the machine structures are categorized. Key issues of design and control for the high-speed permanent magnet machines are reviewed, including bearings selection, rotor dynamics analysis and design, rotor stress analysis and protection, thermal analysis and design, electromagnetic losses analysis and reduction, sensorless control strategies, as well as comparison and selection of sine-wave and square-wave drive modes. Some challenges are also discussed, so that future studies could be focused.