High-Efficiency Line-Start Synchronous Reluctance Motor for Fan and Pump Applications

In the last years the line-start synchronous motors have gained a growing interest thanks to the remarkable energy efficiency, since the operation at synchronous speed ensures the absence of losses in the squirrel cage at steady state. Typical application fields are fans, pumps, compressors and textile industry. Many papers propose line-start PM motors, due to their high efficiency and power density: rare earths magnets feat to this role thanks to the good coercive force, but they are also characterized by very high prices. Moreover, the price volatility of these alloys represents a drawback for mass production. On the other hand, line-start synchronous reluctance machines are very cost-effective and easy to manufacture, and they can compete with the induction motor in terms of reliability and cost. In this paper the design of a high efficiency 3 kW, 2 poles, frame size IEC 100 motor is proposed. A new design procedure is introduced and an optimization algorithm is applied. Two different geometries have been developed and compared, leading to a final design. The capability of the machine both during the starting transient and steady state operation has been analyzed.