A static two-axis model and its application in direct torque control system for brushless doubly fed induction machine

In order to simplify the system structure and improve the control precision, a static two-axis model for brushless doubly fed induction machine is presented in this paper. The two subsystems of the model are respectively built on αβ reference frames of power winding and control winding. On this basis, a direct torque control strategy has been proposed. The flux and torque is estimated on the two static reference frames, avoiding the rotation transformation and speed measurement error. In addition, the switch table applied to both sub-synchronous and super-synchronous is constructed. The machine model and the control strategies are developed in MATLAB. The simulation results show that the estimation of the torque is feasibility. The brushless doubly fed induction machine is stably controlled under a step change in a given speed and load torque. The parameters used in it are less and rotation transformation is avoided.