3-Phase AC Induction Motor

The AC induction motor is a rotating electric machine designed to operate from a three-phase source of alternating voltage. The stator is a classic three phase stator with the winding displaced by 120°.

                                In adjustable speed applications, AC motors are powered by inverters. The inverter converts DC power to AC power at the required frequency and amplitude. The inverter consists of three half-bridge units where the upper and lower switch are controlled complimentarily. As the power device's turn-off time is longer than its turn-on time, some dead-time must be inserted between the turn-off of one transistor of the half-bridge and turn-on of it's complementary device. The output voltage is mostly created by a pulse width modulation (PWM) technique.The 3-phase voltage waves are shifted 120° to each other and thus a 3-phase motor can be supplied.

Applications