Influence of Rotor Slot Number on Flux Weakening Characteristics of Induction Machines

The influence of rotor slot number on the flux-weakening performance of a variable speed induction machine is studied in this paper. The impact of a particular rotor slot number is closely related to the numbers of poles and stator slots. The influence of the number of rotor slots for a range of pole numbers and slots per pole per phase on leakage inductance, magnetizing inductance, torque and torque ripple is discussed. The induction machines with the same outer diameter, stack length and drive circuit are compared over a wide range of slot/pole combinations by analytical and finite element methods. The corresponding optimum rotor slot number that maximizes the operating speed range and minimizes torque ripple is determined.