15-11-2014, 10:26 AM
Abstracts: Three-phase induction motor is widely been used in the industry because of its rugged construction and absence of brushes. However, users need to control the speed of the motor depending on the desired speed and application. Sinusoidal PWM has been a very popular technique used in AC motor control. This is a method that employs a triangular carrier wave modulated by a sine wave and the points of intersection determine the switching points of the power devices in the inverter. So, this project is launched to control the speed of the three-phase induction motor by varying the electrical frequency. In this project, the frequency is adjusted by using the Sinusoidal Pulse Width Modulation (SPWM) technique as a variable frequency drive. The variable frequency pulse width modulation (PWM) signal that controls the applied voltage on the gate drive, which provides the required PWM frequency with less harmonics at the output of the power inverter. The fully controlled bridge voltage source inverter has been implemented with semiconductors power devices isolated gate bipolar transistor (IGBT) or metal oxide semiconductor field effect transistor(MOSFET), and the PWM technique has been employed in this inverter to supply the motor with AC voltage.