Electric Motors and Drives, 2nd Edition

Inverter-Fed Induction Motor Drives 249

when more torque is required) is that by making the right

sudden change to the instantaneous position of the stator

MMF wave, the transition from one steady state to the next is

achieved instantaneously, without the variables hunting

around before settling to their new values. In particular, the

vector approach allows us to overcome the long electrical

time-constant of the rotor cage, which is responsible for the

inherently sluggish transient response of the induction motor.

It should also be pointed out that, in practice, the speed of the

rotor will not remain constant when the torque changes (as

assume ...