High Efficiency and High Speed PM Motors for the More Electric Aircraft

More electric aircraft has been a subject of increasing discussions and research for more than ten years now, both in Europe and in North America. These efforts follow the growing realisation of the benefits that are likely to emerge from the future growth of the more electric aircraft technology. This is evident from the sizes and numbers of research and development programmes currently undertaken on the subject by both aerospace industry and academic institutions. High speed permanent magnet motors, excited by rare-earth magnetic materials, are used extensively in majority of these research programmes. The applications, on more electric aircrafts, often demand motor drives that have very high reliability, energy efficiency and high power density. On of the factors that require significant design consideration is the effect of high speed on the operational performance of the motor. High rotational speed impacts heavily on the rotational losses whilst the high peripheral speed influences the mechanical construction of the rotor. Iron and windage losses can become dominating factors in determining the overall rating and efficiency of the motor. The other important consideration relate to the ability of the motor to generate high torque at low speed, a feature that is very essential in actuation drive systems on the aircraft