Comprehensive Research On Operating Performance And Vibration Characteristics Of Unequal Thick Permanent Magnet DC Motor

For permanent magnet motors,the performance,shape and size of permanent magnets directly affect the operating performance and cost of the motor system.The magnetic pole is adjacent to the air gap,and the shape of the permanent magnet will directly affect the length of the air gap.Therefore,it is of great significance to optimize the design of the permanent magnet magnetic pole when designing the permanent magnet motor.Studies have shown that the use of unequal-thick pole structures can not only save permanent magnet materials and simplify pole processing,but also effectively improve the motor back-EMF waveform,reduce cogging torque,suppress motor torque ripple,and significantly improve the overall performance of the motor.Firstly,the analytical model of radial air gap magnetic field of equal-thickness magnetic pole and unequal-thickness magnetic pole motor considering cogging effect is derived.The two-dimensional finite element model was established in Maxwell electromagnetic software,and the radial air gap magnetic field of the motors with equal thickness and unequal thickness was calculated.Furthermore,by comparing the analytical solution and the finite element solution,the correctness of the finite element model is verified,which lays the foundation for the subsequent simulation.Secondly,the effects of the magnetic pole eccentricity d,the permanent magnet center thickness hm and the polar arc coefficient ap on the motor torque performance and radial electromagnetic force were studied.The magnetic pole eccentricity d and the polar arc coefficient αp have a greater influence on the cogging torque,while hm and d have a greater influence on the electromagnetic torque.The frequency of the radial electromagnetic force is mainly 600 Hz,1200 Hz,1800 Hz,2400 Hz,and 3000 Hz,and the amplitude of the radial electromagnetic force at 600 Hz is the largest.The influence of d and αp on radial electromagnetic force is more obvious,especially on 600 Hz radial electromagnetic force.Then,a three-dimensional finite element model of unequal-thickness permanent magnet DC motor was established,and modal analysis and vibration response characteristic analysis were carried out,which were verified by modal and vibration experiments.The influence rule of magnetic pole eccentric distance d,permanent magnet center thickness hm and polar arc coefficient αp on motor vibration characteristics was further studied.Among them,it has the greatest impact on electromagnetic vibration,and has an impact on the vibration amplitude at various frequencies,followed by the impact on motor vibration,especially on 2400 Hz,which has the smallest impact on electromagnetic vibration.Finally,taking the magnetic pole eccentricity d,the permanent magnet center thickness hm and the polar arc coefficient ap as independent variables,the cogging torque,electromagnetic torque and motor vibration of the motor as optimization goals,the Kriging proxy model was established through 25 sets of samples,and The proxy model is verified,and further combined with the particle swarm optimization algorithm to obtain the optimal magnetic pole parameters.Optimizing the motor not only improves the vibration characteristics of the motor,but also has better motor torque performance.