The Research On The Control Strategies Of Brushless DC Motor Governing System

Brush DC motor commutation mechanical contact often produces commutation sparks and mechanical wear, and it is not conducive to long-term operation of the motor. Brushless DC motor could abandon the mechanical contact commutation by adopting electronic commutation. It has advantages like high efficiency, clear structure. And it is easy to control. Brushless DC motor has been applied to the industrial production, aerospace, and office automation and many other fields. Therefore, in order to provide more theoretic support, the research of the field in brushless DC motor was given more practical significances. In view of the speed controller of brushless DC motor speed control system, two control algorithms have been designed in this paper. Specific works are summarized as follows:Firstly, the background and significance of this topic was introduced, and the research status and the development trend of the brushless DC motor and its control strategies were summarized.Secondly, the mathematical model of the motor has been obtained based on the structure and the work principle of brushless DC motor. And the simulation mode of brushless DC motor speed control system has been set up in MATLAB/Simulink. Simulations have been given to confirm the correctness and the effectiveness of the model of brushless DC motor.Then, on the basis of dynamic Terminal sliding mode control theory, a sliding mode speed controller was designed with the combination of the mathematical models. Traditional speed controller can’t meet the accuracy requirements of complex systems like brushless DC motor control which has many variables and strong coupling. Dynamic Terminal sliding mode controller was designed. The results show that the controller allows the system state to converge to the desired value in a limited time and the steady-state tracking system speed and control precision results were improved at the same time.Finally, in the direct torque control system of brushless DC motor, a new fuzzy variable structure Anti-windup PI controller was designed. For the windup problem existing in the speed controller, the design of variable structure Anti-windup PI controller was realized, and by using the fuzzy theory to adjust the control parameters online. The simulation shows that, when the controller went into the situation of saturation, the system enters the linear region as soon as possible and the overshoot will be reduced by the adjusting effects of the controller. Characters like real-time and the rapid responses are both improved, and the non-static error adjustment of the system is also achieved.