Though the inverter controlled induction motor traction system has been widely used in the railway traction,recently,it′s the availability of high-performance rare-earth permanent magnets of the samarium-cobalt or neodymium-iron-bore types that makes the permanent magnet synchronous motor noteworthy in the railway traction.

It discusses the calculation of NPS (Negative Phase Sequence) current, NPS voltage and unbalance rate in rail traction system with three-phase Yd11 connected transformer, implements the software development for traction flow calculation and NPS analysis, and presents several simulation results.