Design evaluation of several electric machines topologies for propulsion of a railway vehicle

This paper approaches the electromagnetic design and finite-element analysis of two outer rotor machines topologies: radial flux NdFeB permanent magnet synchronous machines and asynchronous machine. The design evaluation of the machines, based on 2-D finite element field analysis, proves that using bonded NdFeB permanent magnets the efficiency of the machine is increased with the penalty of higher costs, due to high price of magnets. Induction machine has the energy conversion efficiency, especially at nominal power, approximately the same. The benefits of the asynchronous machine compared to permanent magnet variants are: lower production costs, higher operating temperature, better robustness, and disadvantages: lower power density, lower power factor.