The Research And Design Of Brushless Direct Current Motor Speed Regulating System Based On BP Neural Network

In modem society,the electrical energy is the secondary energy resources that is most frequently and most commonly used.And as a electromechanical energy conversion device,the electric motor is widely used in every field.For adapting different application scenarios,various kinds of electric motors are emerged.Generally,electric motors are divided into AC motor and DC motor.AC motor has the simple construction and can easily be manufactured,but due to its inefficiency and its bad stating performance,it is unsuitable in some occasions of higher request for speed regulation and starting.DC motor have many advantages,such as,high operating efficiency,good speed regulation performance,etc.Therefore,it is well applied in some driving system.Brushless direct current motor is developed based on traditional brush direct current motor.Comparing to traditional brush direct current motor,it has the features of high torque,high precision and high efficiency,etc.and is widely applied in many control fields,such as,national defense,aerospace,robot,precision machine tool,etc.So,research for the brushless direct current motor speed regulating system have very broad prospect.Classical brushless DC motor control system adopt PID controller.PID controller has feature of simple construction,good reliability,etc.,therefore it has very significant position in motor control fields.But because brushless DC motor control system has feature of nonlinear,strong coupling,etc.and tuning parameters of traditional PID controller depend very on artificial experience,it is very difficult in control system design.BP neutral network has ability of fitting any nonlinear function.In this article,we have detailedly explained algorithm and theory of BP neutral network.And have analyzed its deficiency and have proposed improvement strategy.And BP neutral network is combined with traditional PID controller,so that PID parameter online self-tuning is realized.In MATLAB platform,simulation experiment about PID controller based on BP neutral network is conducted.The result shows that PID controller based on BP neutral network has advantages of fast response speed,small overshoot,good tracking performance and strong robustness,etc.Based on simulation,Brushless Direct Current Motor speed regulating system with ZYNQ is designed and constructed.And hardware circuit is designed,including brushless DC motor driving circuit,current sampling circuit,hall signal detection circuit,serial communicationcircuit,etc.Control strategy adopts software and hardware co-design method of ARM+FPGA.In FPGA,low-level control module is realized,including motor speed reading IP core,PWM signal generation IP core,commutation control IP core.And functional simulation of each module is conducted in Modelsim software in order to test correctness of logic.Because these functions are relatively stationary,in upgrading Integral control algorithm,it don't need to be changed.In ARM,speed+current double closed loop control algorithm,speed ring using BP-PID controller,current loop using PI controller is realized and make the best of advantage that ARM processor implement complex algorithm.Finally,it turned out that the control system achieved high precision and high stability through experiment.