Flux weakening effect of permanent magnet traction motor to its operating characteristics

The paper brings torque, power, efficiency and harmonic analyses of traction drive with permanent magnet synchronous motor (PMSM) during flux weakening operation. There is one way to weak flux of rotor permanent magnets — armature reaction caused by negative flux producing current component. On the other hand, the flux producing current component increases total RMS value of stator current. This effect has influence on losses and efficiency of PMSM. The paper investigates power, efficiency, torque and current characteristics in various operation points of PMSM drive. The analyses are realized on the bases of measurements performed on a special testing stand with PMSM 58 kW.