Research On Brushless DC Motor Control System Based On Improved Sliding Mode Algorithm

Brushless DC motors use electronic switching devices instead of traditional contact commutators and brushes.On the basis of maintaining the characteristics of DC brushed motors,they also have small size,strong load capacity,wide speed adjustment range,and starting current.Because of the characteristics of small size,high stability,long life,etc.,this article takes the DC brushless motor as the research object.Traditional control methods are difficult to meet the control requirements for complex systems with nonlinear,time-varying,multi-variable,unknown structure and parameters,which limits the application of traditional control methods in brushless DC motor control systems.Sliding mode control theory,as a commonly used nonlinear control theory in motor control,can reduce the influence of inaccurate model establishment on the system.Therefore,the sliding mode control method is often used for the control of DC brushless motors,and when the sliding mode controller is used for motor control,it is insensitive to disturbances,and is easily affected by external disturbances,and the existence of chattering problems will seriously affect the stability of the system..In response to this problem,this paper proposes an improved sliding mode control algorithm.First,analyze the control method of the DC brushless motor;secondly,the working principle of the DC brushless motor is studied in detail and its dynamic model is established;and finally on this basis,Completed the following research content:(1)On the basis of the traditional sliding mode variable structure control algorithm,an improved exponential approach rate sliding mode control algorithm is proposed and the controller is designed to analyze its stability;the simulation experiment is compared with the traditional sliding mode algorithm,and the improved algorithm The overshoot is smaller,the response speed is faster,and the robustness is stronger.(2)Combined with the fast terminal sliding mode theory,the fast terminal improved sliding mode control is designed,and the simulation analysis verifies that the algorithm has better dynamic performance.Aiming at the chattering problem of sliding mode control,an integral correction function is introduced.Under the premise of ensuring the stable performance of the system,the algorithm improves the system convergence speed,reduces the switching time,and basically eliminates chattering.(3)According to the overall plan of the brushless DC motor control system,the software and hardware of the control system are designed,and on this basis,an experimental platform based on STM32F103C8T6 is built.The signal waveform and three-phase voltage waveform of the Hall sensor during normal operation of the motor are analyzed,and the speed regulation and acceleration/deceleration experiments of the improved sliding mode algorithm are carried out on the experimental platform.The experimental results show that the improved sliding mode algorithm not only significantly reduces the overshoot and speeds up the response,but also basically eliminates the chattering problem of the motor sliding mode control.