Motor and inverter design criteria for variable-speed and vector controlled AC drives

The robustness, reliability and lack of maintenance requirements of cage induction motors make them an ideal choice for variable-speed drive applications. The authors identify some of the design parameters which affect the overall system behaviour. For the motor, consideration is given to: choice of base frequency, voltage/frequency profile, rotor slot shape, ventilation arrangements and lamination material. For the inverter: voltage ratings, choice of switching frequency for different control strategies and the selection of power devices will be discussed. The validity of the above design approach is demonstrated by results taken from actual designs, many of which are implemented in production equipment