Design and Comparison of Three Different Types of IE4 Efficiency Machines

The demand for highly efficient electric machines has been expanded in recent decade due to increase of energy consumption and the improvement of international standards for high efficiency machines. Although the rare-earth permanent magnet machines usually exhibit high performance, rare-earth resources are limited and their cost is high. In this case, this paper studies and compares the performance and cost of 2.2 kW copper-rotor induction machine (CR-IM), synchronous reluctance machine (SynRM), and PM-assisted synchronous reluctance machine (PMASynRM) achieving IE4 efficiency level. A finite-element method (FEM) is used to validate the performance of three machines. The results show that SynRM can achieve IE4 efficiency level with the lowest cost, but the power factor is a big challenge, PMASynRM has the best performance and a competitive cost advantage compared to CR-IM.