Section 15.6: Speed and Torque Control of Induction Motors
Recall that induction motors are nearly constant (i.e., synchronous) speed machines
The synchronous speed is ns = 120f/p
Ergo, the motor’s speed can be controlled by controlling the stator voltage’s frequency (by way of power electronics)
For further details see text pp. 561-567 for a (mostly) qualitative description of torque-speed control