The Next Generation Motor Control Method: Direct Torque Control (DTC)

Abstract

AbstractDirect Torque Control (DTC) is the latest AC motor control method developed by ABB, In Direct Torque Control all switch changes are based directly on the electromagnetic state of the motor. Optimum switching is determined for every control cycle on a time level of 25 microseconds. That is also the main difference between Direct Torque Control and the traditional AC drive control methods. In DTC, there is no separate voltage-and frequency-controlled PWM modulator. The switch positions of the power module are determined by a calculated stator flux and motor torque. The used selection of the switches forces The stator flux in the direction where the reference values of the torque and the stator flux are achieved. The calculation of the stator-flux is based on an accurate motor model and the measurement of the motor input voltage and current. The measurement of the shaft speed is not needed. The reference value of the torque controller either comes from speed controller or is an external reference. Th...