Analysis And Suppression Method Research Of Torque Ripple For Brushless DC Motor

Currently suppression method of brushless DC motor torque ripple is mainly to optimizethe motor structure and improve control algorithm. Under certain conditions, torque ripple canbe weakened to some extent. But electric vehicle drive motor under complex condition, torqueripple problem is still prominent. Torque ripple can cause torsional vibration of transmissionsystem and directly reduce the reliability of transmission system as well as reduce service lifeof various components. Therefore, combining the characteristics of brushless DC motortorque ripple, torsional vibration damper is developed to impair motor torque ripple forelectric vehicle so as to reduce the adverse impact of transmission system imposed by torqueripple. The main research content is as follows:Firstly, generation mechanism and characteristics of torque ripple is analyzed bystudying the structure and working principle of brushless DC motor. Then torque ripple testsystem based on virtual instrument is developed by using torque sensor, magnetic brake anddata acquisition card etc. The test system is used to measure motor torque ripple and analyzethe real characteristics of motor output torque ripple.Secondly, torsional vibration mathematical model of motor rotor is established and therelationship between motor output torque ripple and torsional vibration is analyed. Byanalyzing the impact of torque ripple imposed by dynamic damper torsion damper andvibration isolation-type torsion damper, it arrives at the conclusion that vibrationisolation-type torsion damper can impair torque ripple of higher motor speed range.Finally, vibration isolation-type torsion damper, whose elastic component is rubber, isselected to impair motor torque ripple. The size of torsion damper is determined according toits stiffness and strength, and3D model of torsion damper is established in CATIA. Stiffness,strength and dynamic characteristics are analyed through static and dynamic simulation oftorsion damper by using software ABAQUS.The research shows that brushless DC motor output torque ripple is mainly commutationtorque ripple. It is linear relationship between frequency and motor speed. Torsion dampercan effectively impair output torque ripple of drive motor when electric vehicle drives atcommon speed.