Research Of Torque Ripple And Noise Related Problems For The BLDC Motor

Brushless DC motors(BLDCM)are widely used in industrial products,digital control machine,micro-processing,aerospace and other occasions for its advantages on high performance,simple control,long-life,and high power density.But the inevitably torque ripple of brushless DC motor in its operation inhibits its application in high-precision applications.Meanwhile,the noise brought by the operation of the BLDCM seriously affects the user experience.Therefore,the related problems of torque ripple and noise of the brushless dc motor have become one of research focus in the research field.This paper presents different control methods to suppress the brushless DC motor torque ripple,and establish the motor noise test platform.Firstly,the structure,mathematical model and operating principle of BLDCM are analyzed.Then this paper analyze in detail the cause of torque ripple of BLDCM and classify the torque ripple.Furthermore,this paper presents different torque ripple suppression methods.The paper introduces the SVPWM control algorithm in detail aiming that back-EMF of BLDCM is sine-wave-like,and this method is applied to the open-loop control,which results that can effectively reduce the commutation torque ripple and the principle torque fluctuation caused by the non-ideal back-EMF.Then,in the double closed-loop control of brushless DC motor speed and current,using the mathematical model of the motor with different control methods,two different non commutation current prediction model are deduced.Two model predictive control(MPC)methods are proposed to suppress commutation torque ripple accordingly,that is,the finite control set model predictive control(FCS-MPC)algorithm and PWM model predictive control(PWM-MPC)algorithm.The different simulation algorithms of BLDCM are simulated in MATLAB/Simulink platform.The simulation results show that it has good effect on commutation torque ripple suppression that adding the present control algorithm.Then,on the basis of theoretical analysis and simulation verification,the motor control system is built.The experiment system realize the SVPWM control algorithm and PWM-MPC control algorithm.And the experimental results show that the proposed algorithm can efficiently suppress the torque ripple.Finally,the causes of motor noise are introduced in detail,and the classification and principle analysis are also carried out.The relationship between noise and torque ripple is described.Aiming at the motor noise,this paper builds a motor noise test system to detect the motor noise under different driving conditions,and obtains the noise spectrum by using the Fourier transform.Through the analysis,the relationship between the brushless DC motor noise and torque fluctuations is found.