Research On Torque Ripple Reduction Of Brushless DC Motor

Brushless DC motor combines the traditional motor body and modern control technology with electromechanical integration,featuring high efficiency,low energy consumption,high efficiency and small size.Therefore,it is widely used in precision instruments,electric vehicles,aerospace,household appliances and other fields.The large torque ripple of the brushless DC motor under the traditional control method is a key factor that restricts its development.The main causes of torque ripple are:cogging torque ripple and commutation torque ripple.Among them,the torque ripple caused by the commutation process is the main part.Under normal circumstances,the torque ripple generated by the commutation process is 20%-25% of the rated torque,and in severe cases it will be more than 50%.In order to reduce this effect,this paper improves on the basis of space vector control,and proposes a control method that can suppress the torque ripple of the commutation process.This paper first analyzes the operating principle and mathematical model of brushless DC motor.A method of synthesizing current to power a motor is proposed.The current vector of the brushless DC motor driven by the ideal square wave current in the two-dimensional stationary coordinate system by transforming the brushless DC motor parameters in the three-dimensional stationary coordinate system(abc)into the variables in the two-dimensional stationary coordinate system(αβ)And the back electromotive force vector is analyzed to obtain its motion trajectory,and then the synthesized current vector is expressed in different power supply intervals.The SVPWM is adjusted by using current vectors of different intervals to ensure that the inverter can follow the change of the drive current during the commutation process,thereby ensuring constant torque.Secondly,the system simulation module is built in the environment according to the mathematical formula that is pushed down,and the traditional current speed double closed loop PI control system and the improved coordinate transformationbased brushless DC motor are simulated.The torque ripple generated by the brushless DC motor under vector control is significantly less than that of the brushless DC motor under the traditional control strategy.Finally,according to the existing conditions of the laboratory,the experimental platform of DSP-based brushless DC motor control system is designed and built.And do software programming.Experiments on the method of suppressing torque ripple under the proposed vector control are carried out.The experimental results can be found consistent with the simulation results,which verifies the feasibility and correctness of the scheme,and thus suppresses the brushless DC motor in the commutation process.