Design Of Direct Torque Control System For Asynchronous Motor

The thesis proposes a novel kind of Direct Torque Control (DTC). The principle of DTC system is showed as follows. The different between the reference of the stator flux' magnetic torque and the instantaneous value of them is used as the input of the control algorithm. The control algorithm realizes two purposes: one is to keep the stator flux's amplitude constant and the other is to make the instantaneous magnetic torque to follow the reference. The algorithm get the reference of the stator current on the conditions that the above purposes is realized and then a predicted working voltage vector is decided which in next step is formed by two adjacent voltage vector of inverter. Zero voltage is used if necessary. Because of the instantaneous control of the stator current, the vibration of the decreased sharply and the responding velocity is improved as well.