I. Introduction
Electric motors are the most important type of industrial loads accounting for approximately 70% of industrial electricity consumed [1]. High efficiency motors can ensure significant reductions in global energy consumption and alleviate the environmental problems. Induction machines (IMs) hold the largest market share among AC motors of different types. NEMA (national electrical manufacturers association) premium efficiency or IEC (international electrotechnical committee) IE3 efficiency class motors are now mandatory in North America. Super-premiuml/E4 and ultra-premium/IE5 efficiency classes are already incorporated in IEC 60034-30 standard [2]. These new efficiency regulations are motivating government, industries and academia to invest time and resources in high efficiency electric machines research. For commercial standard frame induction motors, IE4/ super-premium efficiency is achievable for more than 7.5 kW rated power. At lower power levels (≤ 7.5 kW) that accounts for 79% of the total AC motor market [3], IE4 efficiency is achievable with rare-earth permanent magnet (PM) alternatives whose price/kW is 2 to 4 times that of IMs [1]. This reveals the research gap to find a low cost, higher efficiency alternative to induction motors at low power levels (≤ 7.5 kW).