Research On Torque Ripple Suppression Strategy For Brushless DC Motor Based On The Proportional Resonant Control

Because of the high power density,high efficiency,simple structure,high reliability,large starting torque and good dynamic performance,permanent magnet brushless DC(BLDC)motors have a wide range of applications in industrial and civil areas,such as aerospace,electric vehicles,household appliances,office supplies and other fields.However,the serious torque ripple narrows the scope of high precision and high stability applications.Commutation torque ripple is the main factor affecting the BLDC motor,so the reduction of commutation torque ripple has been the research hotspot of BLDC motors.Based on the analysis of previous literatures about the suppression of commutation torque ripple,a novel control strategy is proposed for the BLDC motors with non-ideal back-EMF.The proposed method combines machine design and current control strategy,which is accomplished in three steps.Firstly,the non-ideal back-EMF data needs to be obtained from the machine design or experimental measurement.Secondly,based on the improved torque harmonic expressions considering the effects of phase current lagging,the main ripple contributors can be found and are also used as the basis of designing the phase current and reducing torque ripple.Thirdly,the improved proportional-resonant current controller(IPRCC)is employed to track the designed reference current in real time.The resonant term parameters' effects on the current controller are discussed through control variate method,and the stability of current controller is analyzed by means of Nyquist and Bode diagram.In this paper,three control methods are compared to verify the feasibility of current designing method and IPRCC.Moreover,the steady-state and dynamic performance is also investigated.