D.C. dynamic braking of induction motors with secondary capacitors

The presence of secondary-circuit capacitance permits large torque to be developed in induction motors at high speeds, with d.c. dynamic braking. Variation of braking torque at fixed speed can be achieved by variation of excitation current or capacitance, or by the inclusion of resistance in series or parallel with the capacitor. Test results are given for an experimental drive with a 3-phase wound-rotor machine. Computed performance curves, taking saturation of the machine into account, give acceptable agreement with the experimental results.