Robust Design of Induction Machines for High-Speed Electric Freight Locomotive Applications

This paper showcases a systematic procedure to design the most efficient re design of a commercially available induction machine to be used as a traction motor in an Electric Freight Locomotive for the rail journey from Tehran to Mashhad. Using Taguchi optimization, copper and aluminium wound versions of the machine are optimized for an 1870-ton load locomotive with a peak power of 1203kW. The driving cycle is summarized using the K-means clustering method to obtain representative points. Full details of the drive cycle and guiding rail adhesion modelling are given and subsequently used in a sequential multi-physics and multi-operation mode robust procedure which optimizes the geometry and cooling parameters whilst taking manufacturing tolerances into account. The paper thus presents a thorough comparative study of aluminium-based and copper-based designs to meet a realistic Electric Freight Locomotive specification. Results indicated that the proposed approach is effective in optimum and robust design of conventional and aluminium induction machines and can be applied to other machine types operating on other rail journeys. Switching to aluminium is one way of improving the recyclability of motors, but in the scenario considered here, results in a 1.1% reduction in efficiency over the driving cycle.