Speed Control of Three-Phase Induction Motor using Direct

Abstract — Direct Torque Control or DTC as it is called is the very latest AC drive technology developed by ABB and is set to replace tr aditional PWM drives of the open- and closed-loop type in the near future. Direct Torque Control describes the way in which the control of torque and speed are directly based on the electromagnetic state of the motor. DTC is the first technology to control the “real ” motor c ontrol variables of torque and flux. Because torque and flux are motor parameters that are being directly controlled, there is no need for a modulator, as used in PWM drives, to control the frequency and voltage. This, in effect, cuts out the middle man and dramatically speeds up the response of the drive to changes in required torque. DTC also provides precise torque control without the need for a feedback device