Rotor Optimization of a Synchronous Reluctance Machine for Railway Applications

This article presents a design optimization strategy of a synchronous reluctance motor for railway applications, aimed at finding a trade-off solution among selected performance metrics in different operating points. The methodology consists in deriving, via finite element analysis, the machine fluxes-currents relationships required for calculating the torque-speed curve. Consequently, the trajectories relative to the main control strategies in the d-q axes reference frame are derived to obtain the torque-speed characteristic. By varying the rotor layout only, an optimisation is carried out by analysing two relevant operating points in the torque speed characteristic, i.e. rated torque - base speed point and the transition point between flux weakening and maximum-torque-per-voltage operations. Results reveal a clear trade-off among these performance indexes underlining the importance of a multi-objective design approach.