Variable speed drives using induction motors and direct torque control

Direct torque control is a method of controlling an inverter and induction motor which provides excellent performance without rotor position sensing; that is, it is a high performance sensorless system. New signal processing technology has made it possible to utilise new control principles and all switch changes of the inverter are based on the electromagnetic state of the motor. There is no need for a separate PWM modulator between the motor and inverter control and this provides greatly improved performance.