The operation of an induction motor controlled by a Variable Frequency Drive (VFD) is illustrated with this Demonstration. You can choose from several National Electrical Manufacturers Association (NEMA) motor designs. You can also select the plot to include the induction generator region of operation.

The torque developed by an induction motor is determined by means of the formula , where is the voltage induced in the blocked rotor, is the resistance of the rotor, is the reactance of the blocked rotor, is the rotor slip, and is the synchronous speed.

Equations and principles referenced from: C. I. Hubert, Electric Machines: Theory, Operation, Applications, Adjustment, and Control, 2nd ed., Upper Saddle River, NJ: Prentice Hall, 2002.