BLDCM Control System Research Based On The Sliding Mode Observer

Brushless DC motor has been concerned widely by many advantages,such as strong stability,wide speed range,high power density and so on.In order to control it accurately,mechanical position sensors are often used to determine the real-time position information of the rotor in the field of industry.However,the installation of sensors will bring many problems to the system,such as increasing complexity,reducing reliability and increasing cost,etc.Therefore,more and more researchers have begun to apply the sensorless technology to the brushless DC motor control system in recent years.Sliding mode control method is one of the most effective methods to control the nonlinear system.It changes to external disturbance and internal parameter alterations phenomenon showed very strong anti-interference,using this characteristic,adding sliding mode observer into the sensorless control system for brushless DC motor,which can be implemented for the indirect measurement of rotor position in real time,and then the sensorless control of brushless DC motor can be achieved.The sliding mode control method itself has a serious buffeting problem.By optimizing the approaching law,the buffeting phenomenon can be weakened to a certain extent.Firstly,the basic structure,working principle,mathematical model and operating characteristics as well as the “three-stage” in the start mode of brushless DC motor are studied.Meanwhile,the common methods to obtain rotor position in real time without position sensor are introduced,and the estimation method of back electromotive force of brushless DC motor based on sliding mode observer is focused on.Secondly,the principle of sliding mode control is introduced,a new sliding mode reaching laws is introduced to build a new sliding mode observer,the advantages of it in anti-interference and rapid corresponding are analyzed through mathematical formula deduction,and a double closed loop control system of brushless DC motor is designed based on this.Thirdly,the simulation analysis is carried out with the Matlab/Simulink platform to verify the correctness and superiority of the proposed control method.Finally,the hardware experimental platform of brushless DC motor sensorless control system is built by taking TMS320F2812 as the core of control.At the same time,software program is used to verify the whold control system.The experimental results are get and the experimental analysis are given.The experimental results show that the brushless DC motor sensorless control system based on the new sliding mode observer is good in running performance,and can accomplish brushless DC motor status acquisition,speed adjustment,location estimation and so on.