| With the development of power electrical devices and permanent magnet materials, the permanent magnet synchronous motor has a wider practical application space. Direct Torque Control with the advantages of simple control and quick response plays an important role in the high-performance control method of AC motor. In this paper, the direct torque control of permanent magnet synchronous motor is introduced. For the problems of the traditional direct torque control, such as large flux linkage and torque ripple, bad robustness,unavoidable mechanical sensor and so on, the corresponding improved control strategy is given. The main contents are as follows:Firstly, in order to overcome the problems of the traditional direct torque control, the space voltage vector PWM technology is introduced. The working principle of the technique is described in detail in the paper. And the simulation results show that the method is effective.Secondly, in the system with uncertainties and outside interference, in order to enhance the robustness of the system and improve the dynamic and static performance of the system, a sliding mode direct torque control strategy based on the space voltage vector PWM technique is presented. And the sliding mode controller for flux linkage and torque is designed. The simulation results show that the control strategy can effectively restrain the influence of external disturbance and enhance the robustness of the system.Finally, in the speed control system of permanent magnet synchronous motor with closed-loop control, the use of sensor can cause the problem of large size of motor, poor environment and high cost. To solve this problem, the VSS(variable structure sliding mode) observer is designed to estimate the speed.Based on the sliding mode direct torque control, a direct torque control system of the double sliding mode is presented by using the VSS observer. And the simulation results prove the feasibility of the strategy.
|
PDF Full Text Request