Multiphase cage induction motors for controlled drives

General control possibilities of the drive with a multiphase cage induction motors having number of phases greater than 3 are subject of the paper. The motors have additional properties for speed control distinguishing them from the standard 3 phase motors. They are connected with operation at various sequences of supplying voltages due to the inverter control and possible operation with open-circuited phases. This allows for different no load speeds at the same frequency. Applying vector or scalar control this feature extends applications for miscellaneous drive demands including sensor-less control. The main features of the motors depend mainly on type of the stator winding for a given number of phases. Example of operation was presented for a 9-phase motor, though general approach was discussed. The motor was supplied from a voltage source inverter and controlled with field orientation under forced currents. The mathematical model of the motor was reduced to the minimum form incorporating all most important physical features and appropriate for the control law formulation.