Abstract
In this paper three voltage control strategies for three-phase ac voltage regulator have been studied. These strategies depend on varying the stator ac voltage to control the speed of three-phase induction motor. These strategies are symmetrical angle control (SAC), constant pulse width modulation control (CPWM), and saw-tooth pulse width modulation control (SPWM). The system consists of six bidirectional switches. Performance evaluation of the motor under the different switching techniques is shown. The simulation of the system is carried out by PSIM computer program. The simulation results show stable operation for wide range of speed control. The level of harmonics in the supply currents and power factor has been evaluated for different control strategies.