Design Strategy and Comparison of Four PM Motor Topologies for a 2kW Traction Application

This paper discusses the design optimization and comparison of four permanent magnet machines with different rotor topologies for a 2kW traction application. The rotor topologies considered include the surface mount, spoke type, radial bar and v-shaped topologies. Special attention is given to the optimization strategy and three alternative ways of formulating the optimization problem are given and the relative merits of each formulation are discussed. Performance calculations are based on 2D finite element analyses of all the critical operating points across the required operational speed range. The objective of the optimization is to minimize the material cost of the machine. Despite the popularity of interior permanent magnet machines, this study shows that the surface mount topology can be a strong competitor in this regard, even when a constant power speed range equal to four times the base speed is required.