Research On Commutation Torque Ripple Reduction Strategy Of Permanent Magnet Brushless DC Motor

The permanent magnetic brushless DC motor(BLDCM)has good mechanical characteristics and speed regulating performance.Because of its small size,simple structure,reliable operation,simple control,high power density and large torque,BLDCM has been widely used in various fields of the national economy such as industrial robots,medical devices,aerospace technology,chemical industry,textile industry,automobile industry,household appliances and so on.However,because of its unique physical structure and control strategy,the torque ripple is too large for BLDCM.And the torque ripple of the commutation is the special torque ripple of the permanent magnet brushless DC motor.This problem seriously affects the stability and reliability of the permanent magnet brushless DC motor,so it limits its scope of use.This paper from the origin of BLDCM commutation torque ripple,through mathematical analysis to calculate the factors of the BLDCM commutation torque ripple effect.By controlling these factors,the commutation torque ripple of the BLDCM is effectively suppressed.First,the research background,research significance and development status of BLDCM is introduced at the beginning of this paper.Then this paper analyzes the cause of the torque ripple of the permanent magnet brushless DC motor,and classifies the torque ripple of the motor according to the reasons.The current research status of commutation torque ripple suppression technology for BLDCM is introduced.Next,introduces the basic structure and working principle of BLDCM.By analysing the running state of each period of BLDCM,the mathematical model of BLDCM is deduced.Based on the mathematical model of BLDCM,the mathematical expression of electromagnetic torque of motor under different running states is deduced,and it is used as a basis for studying commutation torque ripple of BLDCM.Secondly,the cause of the commutation torque ripple of BLDCM is introduced in detail.First,the influence of several common PWM modulation modes on commutation torque ripple suppression of BLDCM is introduced,and the advantages and disadvantages of these control strategies are analyzed.Then,a simple permanent magnet brushless DC motor torque ripple suppression strategy is proposed according to the reason of commutation torque ripple,which is in front of the three-phase inverter with a conventional SIMO DC-DC converter circuit,by changing the input voltage of the motor inverter in the commutation period and the conduction period of the motor to effectively suppress the commutation torque ripple of the motor.Finally,in order to verify the correctness and effectiveness of the proposed method,the proposed control strategy is verified.At first,the mathematical model of BLDCM and a simulation system of the whole control strategy are built in the MATLAB/Simulink software environment.The correctness and effectiveness of the proposed method for the commutation torque ripple of permanent magnet brushless DC motor is verified by simulation.Next,the corresponding BLDCM controller is made.In the Cadence Pspice simulation software,a single inductor and two output DC-DC conversion circuit and the corresponding hardware control circuit are designed.Based on the simulation results,we draw the corresponding PCB schematic and layout in Altium Designer,and then make a prototype to measure the functions of the above circuit design is correct.Secondly,the corresponding software control program is programmed based on TMS320F28335,and the program is debugged and tested.At last,the hardware circuit and the software circuit are combined to build the controller of the BLDCM commutation torque ripple,and the problems in the experiment are analyzed,and the shortcomings of the designed motor controller are summarized and improved.