Vibration Analysis And Optimization Of Hybrid Permanent Magnet Motor Considering Magnetic Material Inconsistency

Permanent magnet motor has become the first choice for driving motors of new energy vehicles due to its advantages of high power density,high efficiency and strong magnetic weakness.With the continuous pursuit of lightweight development of new energy vehicle drive motor,the problems of vibration and noise in operation become increasingly prominent.The radial electromagnetic force existing in the motor air gap is the main factor causing electromagnetic vibration of the motor.The permanent magnet motor uses rare earth permanent magnet material as the power source.There are a lot of uncertain factors in the processing and manufacturing process of magnetic material,which leads to the inconsistency of magnetic material in the motor after processing,thus affecting the vibration and noise of the motor.Therefore,how to reduce the negative impact of magnetic material inconsistency on motor vibration and noise,so that the motor has good vibration and noise performance and high performance characteristics,has become one of the main research directions of high-quality permanent magnet motor.In this paper,the radial electromagnetic force distribution of the motor is deduced and summarized in the case that the ideal is inconsistent with the magnetic material.On this basis,a multi-objective optimization design method considering the magnetic material inconsistency of motor was proposed to improve the vibration and noise performance of motor while maintaining good torque output performance.Based on this,this paper takes a combined permanent magnet motor with a polegroove mix ratio of 12/10 as the research object,and constructs a multi-physical field coupling model for motor vibration and noise analysis.The specific work content is as follows:1.The source and distribution of radial electromagnetic force are obtained by studying and analyzing the radial electromagnetic force theory of motor under the condition that the ideal and magnetic material are inconsistent.Based on this,the radial electromagnetic force distribution of a combined permanent magnet synchronous motor with 12 slots and 10 poles is calculated under the condition that the ideal is inconsistent with the magnetic material,and the radial electromagnetic force is taken as the hub to contact the electromagnetic vibration noise of the motor,and the dominant harmonic of the radial electromagnetic force causing the vibration noise of the motor is defined.2.In order to make the motor achieve low vibration and noise performance and have good torque output capacity,a multi-objective optimization design method considering the motor magnetic material inconsistencies was proposed for motor vibration and noise.In this method,the radial electromagnetic force harmonics that dominate the vibration and the torque and torque ripple of the motor are set as the design objectives to be optimized.Sensitivity analysis method and the second generation non-dominated genetic algorithm(NSGA-II)are adopted to optimize the design variables of the motor,aiming at maintaining good torque performance and improving the vibration and noise performance of the motor.3.For the stator subsystem,a holistic finite element model is built,which includes the end-covers,supports,casing,and stator.The finite element method is adopted to study the modal characteristics of the motor structure,and to explore and analyze the influence of the end-covers,supports,and casing on the overall modal characteristics of the motor.Additionally,a comparison will be made between the natural frequencies and mode shapes of the motor in the constrained and free modes.4.The multi-physical field coupling model of motor vibration and noise analysis was constructed,the finite element method was used to calculate the motor vibration and noise,and the amplitude and sound pressure level before and after the motor optimization were compared and analyzed.The rationality of the motor optimization design method adopted in this paper was verified,which effectively weakened the negative impact of magnetic material inconsistency on motor vibration and improved the reliability of motor design.5.The experimental platform of the motor was constructed,and the basic electromagnetic performance of the torque under steady state and the reverse potential performance of the motor under no-load state were tested.For the stator structure system,the hammer method is used to test its free mode and test the vibration acceleration of the prototype.In order to verify the rationality and accuracy of the motor vibration analysis and optimization in this paper,the calculation results of the model are compared with the experimental test results.