Stator current and power factor optimization in an IPMSM for railway traction application

The objective of this paper is to compare two control strategies aimed at optimizing stator current and power factor in the constant torque operation zone on railway traction applications when interior permanent magnet synchronous machines (IPMSM) are used. Both control strategies are the classical “zero d-current”, which is used in most of industrial applications, and the Most Torque per Amp (MTPA) technique, which optimizes the torque with the lowest current. A simulation study has been carried out with different saliency interior permanent magnet syncronous machines, in order to demonstrate that MTPA control strategy allows stator current and power factor optimization, specially if high saliency IPMSM are used. Finally, experimental results with a full-scale 100kW prototype have been carried out, confirming the study fulfilled in simulation.