ASPECTS OF INDUCTION MOTOR STATOR VOLTAGE AND FREQUENCY CONTROL

Direct implementation of Constant Flux Control of Induction Motor is difficult due to the lumped nature of winding parameters. Engineers have tried to solve this problem by using Volts/Hertz control which permits the indirect control of flux. To make full use of the motor torque capability at start and low speed, a modified Volt/Hertz control strategy which utilises low frequency boost-voltage is developed in this book. This, unlike the basic Volts/Hertz control, provides a boost-voltage at low frequencies thereby compensating for the stator impedance drops, offering constant flux operation and maximum motoring torque from zero to rated speed. This modified strategy is applied in the closed loop control of Induction Motor using Six Step Inverter. The results obtained show that variable voltage and frequency control allows simultaneous realization of good running and transient performances from squirrel cage induction motor which, inherently, is not capable of variable speed operation. All MATLAB/SIMULINK files used in realizing these results are included as appendix. The book is highly recommended for graduate level teaching and research in the area of Electric Machines and Drives