CN-116306151-B - Hybrid permanent magnet structure design method for reducing vibration of permanent magnet motor

CN116306151BCN 116306151 BCN116306151 BCN 116306151BCN-116306151-B

Abstract

The invention discloses a hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor, which solves the problem of overlarge vibration of the permanent magnet motor. The method adopts two or more permanent magnet materials with different residual magnetic densities, adopts proper parameters to combine into a required mixed permanent magnet, and adopts the maximum residual magnetic density to magnetize the mixed permanent magnet during magnetizing. After the permanent magnet motor adopts a mixed permanent magnet structure, the harmonic content of a permanent magnet field can be obviously reduced, the sine degree of an air gap field of the motor is improved, the radial electromagnetic force density of low space order generated by the action of the permanent magnet field is further weakened, the electromagnetic vibration of the motor is reduced, and the problem of overlarge motor vibration is obviously solved.

Inventors

ZHAO WENXIANG
HE QINGJUN
TIAN WEI
SUN YUHUA
JI JINGHUA

Assignees

江苏大学

Dates

Publication Date: 20260512
Application Date: 20230323

Claims (8)

1. A structural design method of a hybrid permanent magnet for reducing vibration of a permanent magnet motor is characterized by comprising the following specific steps: Step 1, determining dimension parameters of a traditional permanent magnet motor, wherein the dimension parameters comprise slot pole proportion, inner and outer diameter dimensions of a stator, length of an air gap between a stator and a rotor, and pole arc coefficient and thickness parameters of the traditional permanent magnet; Step 2, modeling a traditional motor, simulating the modeled model by adopting finite elements, solving electromagnetic force and carrying out harmonic analysis, and determining main vibration orders and permanent magnet density harmonic orders which cause motor vibration; step 3, determining a mixed permanent magnet structure model, the number of mixed permanent magnet blocks and the types of permanent magnets according to the size parameters of the motor; Step 4, constructing a magnetomotive force expression of the mixed permanent magnet by using an analytic method, and carrying out harmonic analysis on magnetomotive force of the mixed permanent magnet structure by using a numerical method; in the step 4, the permanent magnet magnetization length expression l c of the hybrid permanent magnet structure is: (1); Wherein l c is the magnetization length of the permanent magnet, R is the radius of the outer circle of the permanent magnet, theta is the change angle of the mixed permanent magnet, h pm is the height of the permanent magnet, alpha p is the polar arc coefficient, and p is the pole pair number; in the step 4, the magnetomotive force expression F c calculated by the permanent magnet of the hybrid permanent magnet structure is: (2); Wherein F c is the magnetomotive force calculated by the permanent magnet with a mixed permanent magnet structure, theta c1 is the angle of the middle permanent magnet, H c1 is the magnetic field intensity of the middle permanent magnet, and H c2 is the magnetic field intensity of the permanent magnets at two sides; Step 5, reducing the magnetomotive force harmonic content of the permanent magnet by adopting a multi-target genetic algorithm, and determining various variable parameters in the mixed permanent magnet structure; step 6, introducing the optimized mixed permanent magnet structure model into finite element software for simulation, and calculating permanent magnet flux density harmonic waves and electromagnetic force harmonic waves; And 7, performing multi-physical field coupling on the motor three-dimensional model and the electromagnetic model in finite element software, performing motor vibration analysis to obtain a vibration result of the hybrid permanent magnet structure, and verifying the effectiveness of the invention.
2. The method for designing the hybrid permanent magnet structure for reducing the vibration of the permanent magnet motor according to claim 1 is characterized in that in the step 1, the adopted motor is a 48-slot/8-pole permanent magnet synchronous motor and comprises four parts including a stator, a winding, a permanent magnet and a rotor, the outermost layer is the stator, the stator slot comprises the winding, the innermost layer is the rotor, the permanent magnet is adhered to the outer surface of the rotor, the winding structure is in a single-layer modularized double-three-phase mutual difference 30-degree configuration, and the permanent magnet with the traditional structure adopts samarium cobalt permanent magnet SmCo32.
3. The method for designing the hybrid permanent magnet structure for reducing the vibration of the permanent magnet motor according to claim 1, wherein in the step 2, the main vibration of the motor is the second-order vibration at the frequency of 6 times and the zero-order vibration at the frequency of 12 times, wherein the zero-order vibration at the frequency of 12 times is mainly generated by the action of the fundamental wave 4 th harmonic wave and 44 th harmonic wave of the permanent magnet, the 12 th harmonic wave and 36 th harmonic wave of the permanent magnet, the 20 th harmonic wave and 28 th harmonic wave of the permanent magnet, and the second-order vibration at the frequency of 6 times is mainly generated by the action of the permanent magnet 20 th harmonic wave and the armature 26 th harmonic wave, 30 th harmonic wave and the permanent magnet 28 th harmonic wave and the armature 26 th harmonic wave.
4. The method for designing the mixed permanent magnet structure for reducing the vibration of the permanent magnet motor according to claim 1 is characterized in that in the step 3, the adopted mixed permanent magnet structure is samarium cobalt permanent magnet SmCo32 with high remanence in the middle, the remanence is 1.13T, samarium cobalt permanent magnets SmCo24 with low remanence are arranged on two sides, the remanence is 1.01T, the mixed permanent magnets are bonded by glue before magnetizing, and the mixed permanent magnets are magnetized in parallel with the maximum remanence of 1.13T.
5. The method for designing the hybrid permanent magnet structure for reducing the vibration of the permanent magnet motor according to claim 1, wherein in the step 5, the optimization variables of the multi-objective genetic algorithm are determined to be the hybrid permanent magnet pole arc coefficient α p , the intermediate permanent magnet angle θ c1 and the permanent magnet height h pm , the variation range of each optimization variable is determined according to the hybrid permanent magnet structure, and the optimization targets of the multi-objective genetic algorithm are that the magnetic density harmonic of the hybrid permanent magnet is minimum in the amplitudes of 20 times B 20th and 28 times B 28th , and the average electromagnetic torque T avg is maximum.
6. The method for designing a hybrid permanent magnet structure for reducing vibration of a permanent magnet motor according to claim 1, wherein in the step 5, correlation analysis is performed on the optimized variable parameters and the optimized target parameters of the multi-target genetic algorithm, and the sensitivity of the optimized variable parameters is determined according to the formula (3); (3); Where S ni is the computation sensitivity, f is the optimization target parameter response, and z i is the optimization variable parameter value.
7. The method for designing the hybrid permanent magnet structure for reducing the vibration of the permanent magnet motor according to claim 1, wherein in the step 5, a sample point is determined by a center test design BBD method, and a sample point optimization target value is obtained by adopting an analytic method and finite element simulation; (4); Wherein Y is an optimization target parameter, beta 0 ,β j ,β jj and beta ij are second-order response surface regression coefficients, and X i and X j are optimization variable parameters; Performing multi-objective genetic algorithm depth optimization on the solved second-order response surface regression proxy model to obtain a pareto solution set; substituting the pareto solution set optimization result into an analytic type, calculating magnetomotive force harmonic waves of the mixed permanent magnet by adopting a numerical method, and determining an optimal mixed permanent magnet structure model.
8. The method for designing the hybrid permanent magnet structure for reducing the vibration of the permanent magnet motor according to claim 1 is characterized in that in the step 6, the determined hybrid permanent magnet structure model is imported into finite element software for simulation analysis to obtain permanent magnet flux density harmonic waves, electromagnetic force harmonic waves and average electromagnetic torque, and in the step 7, the motor three-dimensional model and the electromagnetic model are subjected to multi-physical field coupling simulation analysis in the finite element software to obtain the vibration acceleration of the surface of the motor shell.

Description

Hybrid permanent magnet structure design method for reducing vibration of permanent magnet motor Technical Field The invention relates to a hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor, and belongs to the field of low-vibration permanent magnet synchronous motor application. Background The permanent magnet motor has the characteristics of high power density, high efficiency and the like, and is widely applied to the fields of aerospace, ship propulsion, electric automobiles and the like. However, the traditional permanent magnet motor is easy to generate rich magnetic density harmonic waves due to low air gap magnetic field sine, and further generates larger radial electromagnetic force harmonic waves, so that the motor generates larger vibration, and the stable operation of the motor is influenced. At present, the low vibration performance of the motor is realized mainly by changing the structures and the shapes of a rotor, a permanent magnet and a stator, however, the traditional method has certain limitation on specific implementation and has certain influence on the running performance of the motor. The literature is based on the weakening [ J ]. Electrician technical report of the pole frequency vibration of the surface-mounted permanent magnet motor of the staggered unequal magnetic pole of the segmentation, 2023,38 (04): 945-956. Introduce a method for reducing the motor vibration of the structure of the staggered unequal magnetic pole of segmentation, this method divides the magnetic pole equally into two sections in the axial direction, carry on the axial deviation of the magnetic pole in the zero crossing area of the magnetic flux density and improve the air gap field. However, the method can increase the installation difficulty of the permanent magnet, generate unbalanced axial force in the axial direction, influence the stable operation of the motor, and simultaneously increase the range of the zero crossing region of the magnetic flux density, reduce the effective magnetic flux and reduce the capacity of the motor to output torque. The Chinese patent application No. CN202110255720.2 discloses a design method of a low-vibration permanent magnet motor modified rotor structure, which reduces the amplitude of an air gap flux density harmonic wave which plays a main role in vibration noise by adopting two rotor modification methods of sine harmonic wave attenuation and sine eleven harmonic wave attenuation, improves the sine degree of the air gap flux density of the motor, further weakens the radial electromagnetic force of low space order, and achieves the aim of reducing the vibration of the motor. However, the modification curve of the modification mode is complex, the processing requirement on the permanent magnet is high, meanwhile, the surface roughness of the surface-mounted rotor can be increased due to the irregular surface of the permanent magnet, the wind friction loss and wind noise during the operation of the motor are increased, and the operation efficiency of the motor is affected. Chinese patent application No. CN202122964560.7 discloses a rotor oblique pole of a permanent magnet motor, which adopts a V-shaped oblique pole structure to reduce the harmonic content of an air gap magnetic field, reduce cogging torque and torque fluctuation, achieve the purpose of reducing motor vibration and noise, and simultaneously, the symmetrical design can weaken axial counter force at two ends of the rotor, thereby ensuring mechanical reliability. However, the V-shaped oblique pole is formed by superposing a plurality of sections of rotors, so that the implementation difficulty is high, and meanwhile, the precision of the rotor surface and the rotor inner hole after superposition is poor, so that the problem of radial unbalance is easily caused. Disclosure of Invention The invention aims to solve the defects in the prior art, and provides a structural design method for a hybrid permanent magnet for reducing the vibration of a permanent magnet motor. In order to improve the vibration performance of the motor, the invention is realized by adopting the following technical scheme, namely a structural design method for reducing the vibration of a permanent magnet motor by a mixed permanent magnet, which comprises the following specific steps: Step 1, determining dimension parameters of a traditional permanent magnet motor, wherein the dimension parameters comprise slot pole proportion, inner and outer diameter dimensions of a stator, length of an air gap between a stator and a rotor, pole arc coefficient and thickness of the traditional permanent magnet and the like; Step 2, solving the electromagnetic force of the traditional permanent magnet motor by adopting a finite element method, carrying out harmonic analysis, and determining the main vibration order and the permanent magnet density harmonic order which cause motor vibration; step 3, determin