High speed electrical machines

Thanks to the recent advances in the field of power electronics, the interest of industry and academia towards high speed electrical machines has increased in the last years also due to the their potential advantages in terms of increased power density and elimination of gear-boxes. Possible applications of such technology can range from aerospace field to the generation of electrical energy from renewable sources, and cogeneration. The maximum operating frequency of the electrical machines is limited by losses in magnetic materials. New ferromagnetic materials capable of extreme working conditions (high temperatures, high mechanical stress and vibration) will be considered for the design of novel electrical machines. High performances and low power losses have to be guaranteed also at high frequencies and in presence of harmonics. Such requirements are a major limit for the use of traditional materials. The above mentioned technologies will be also applied in the field of wind power generation and cogeneration. Non-conventional electrical generators, having radial or axial flux and ring structures with high pole number, will be considered. Direct drive generation systems will also allow to reduce the overall dimension and increase efficiency of the devices. Finally, the design stage cannot be considered separate from the development of the electric machine control system to ensure optimum utilization of the entire energy conversion system. In particular, sensorless control strategies (without position and speed sensors) are very interesting to increase system reliability and reduce its complexity.