Modeling And Control Of A 4-Pole/8-Pole Induction Motor For Smooth Torque Production During Electronic Pole Changing

The pole changing motor drive is an appealing solution to address the wide speed operation desired in traction applications. The modeling and control of a 4-pole/8-pole induction motor with bar winding is discussed in this paper. The dual-pole operation is accomplished with indirect field-oriented control by supplying 4-phase currents during 8-pole operation, in low speed region and 8-phase currents during 4-pole operation, in high speed region. The electronic pole changing is enabled with a step change in torque command and a ramped change in rotor flux command to obtain a smooth and continuous torque. The co-simulation results of the finite element analysis (FEA) motor model coupled with a circuit simulator are provided, which shows the behavior of torque and stator flux during pole changing. A mathematical d-q model is developed to aid in rapid controller tuning of the drive which is validated with the FEA results. This paper shows insights into the pole changing behavior with optimum transition time of torque and flux commands, to minimize the torque and flux transients.