Comprehensive cost optimization study of high-efficiency brushless synchronous machines

Due to the increasing significance of energy saving, multiple regulations have been introduced by countries or international organizations regarding the efficiency of electric drives, e.g. the IEC 60034-30 [1]. In the past, many companies replaced induction machines (IMs) by permanent magnet excited synchronous machines (PMSMs). This lead to a considerable increase of the efficiency, but due to the fluctuating price of the permanent magnets, especially of Neodymium-Iron-Boron(NdFeB)-magnets, the cost of PMSMs is hardly predictable. Therefore, many manufacturers are investigating in synchronous reluctance machines (SyncRM) now. In this article, the motor design for standardized rated power Prate = 3kW and nominal synchronous speed of nrate = 1500rpm is taken into consideration. Different motor topologies are analyzed regarding the trade-off between efficiency and material costs, including PMSMs and SyncRMs. This is done for two different cost scenarios. Finally, the cheapest designs that fulfill the IE-2 and IE-3 requirements, respectively, can be determined.