Answer Happy

A 400 V, 50 Hz, 6-pole, 940 rpm, star connected induction motor has the following parameters: stator and rotor resistances are 1.25 each, and stator and rotor leakage reactance are 2 each (magnetising reactance can be neglected). The motor is controlled by simultaneous stator voltage and frequency variation. Voltage boost is not used and the motor is controlled using V/f = constant law. The motor is supplied from a three-phase voltage source inverter a) The motor operates at 25 Hz. Calculate the ratio of the maximum torque at this frequency with respect to the one at rated frequency, for both motoring and generation. [5 marks] For the motoring case the ratio is: Number For the generation case the ratio is: Number