DTC is direct torque control (Directtorquecontrol), which is a way for the inverter to control the torque of the three-phase motor.
The method is to calculate the estimated values ??of motor flux and torque based on the measured motor voltage and current. After controlling the torque, the motor speed can also be controlled to directly control the torque. The control is a patent of the European ABB company.
In direct torque control, the stator magnetic field is obtained by integrating the stator voltage. The torque is estimated based on the inner product of the estimated stator flux vector and the measured current vector.
The magnetic flux and torque will be compared with the reference value. If the error between the magnetic flux or torque and the reference value exceeds the allowable value, the power crystal in the frequency converter will switch to reduce the error in the magnetic flux or torque. Can be reduced as quickly as possible. Therefore direct torque control can also be regarded as a hysteresis or relay control.
Extended information
The different characteristics of the DTC system and the VC system are:
1. The control of torque and flux linkage adopts two-position bang-bang control converter, and directly use these two control signals to generate the SVPWM waveform of the voltage in the PWM inverter, thus avoiding the decomposition of the stator current into torque and flux components, eliminating the need for rotation conversion and current control, and simplifying the control The structure of the device.
2. Select the stator flux as the controlled variable, instead of selecting the rotor flux as in the VC system. In this way, the model for calculating the flux can not be affected by changes in the rotor parameters, which improves Control system robustness. If the law of stator flux control is deduced from a mathematical model, it is obviously more complicated than when the rotor flux is oriented. However, due to the use of bang-bang control, this complexity has no impact on the controller.
Baidu Encyclopedia - Direct Torque Control