A hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor

Abstract

The application discloses a hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor, and solves the problem of excessive vibration of the permanent magnet motor. The method is to adopt two or more kinds of permanent magnet materials with different residual magnetism densities, adopt appropriate parameters to combine into a required hybrid permanent magnet, and magnetize the hybrid permanent magnet with the maximum residual magnetism density during magnetization. After the permanent magnet motor adopts the hybrid permanent magnet structure, the harmonic content of the permanent magnet magnetic field can be significantly reduced, the sinusoidal degree of the motor air gap magnetic field is improved, and then the low space order radial electromagnetic force density generated by the action of the permanent magnet magnetic field is weakened, the electromagnetic vibration of the motor is reduced, and the problem of excessive vibration of the motor is obviously improved.

Description

TECHNICAL FIELD

[0001] The application 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 motors. BACKGROUND

[0002] Permanent magnet motors have been widely used in aerospace, ship propulsion and electric vehicles due to their high power density and high efficiency. However, traditional permanent magnet motors are prone to produce rich magnetic flux density harmonics due to the low sinusoidal nature of the air gap magnetic field, which in turn produces large radial electromagnetic force harmonics, resulting in large motor vibration and affecting the smooth operation of the motor. Currently, the low-vibration performance of the motor is mainly achieved by changing the structure and shape of the rotor, permanent magnet and stator. However, the traditional method has certain limitations in specific implementation and has certain impact on the operation performance of the motor.

[0003] Document "Reduction of Axial Force and Radial Force of Surface-Mounted Permanent Magnet Motor Based on Subsection Interleaved Unequal Magnetic Pole Structure" (Journal of Electrical Engineering Technology, 2023, 38(04): 945-956) introduces a method for reducing motor vibration based on subsection interleaved unequal magnetic pole structure. This method divides the magnetic pole into two sections in the axial direction and shifts the magnetic pole in the axial direction in the magnetic flux density zero-crossing area to improve the air gap magnetic field. However, this method increases the difficulty of installing permanent magnets and produces unbalanced axial force in the axial direction, affecting the smooth operation of the motor. At the same time, this method increases the range of magnetic flux density zero-crossing area, reduces the effective magnetic flux and reduces the ability of the motor to output torque.

[0004] Chinese invention patent application No. CN202110255720.2 discloses a design method for a low-vibration permanent magnet motor modified rotor structure. By using two rotor modification methods, i.e. sinusoidal harmonic weakening and sinusoidal minus tenth harmonic weakening, the amplitude of air gap magnetic flux density harmonics which mainly affect vibration and noise is reduced, the sinusoidal degree of motor air gap magnetic flux density is improved, the low-space order radial electromagnetic force is weakened, and the purpose of reducing motor vibration is achieved. However, the modification curve of this modification method is complex, the processing requirement for permanent magnets is high, and the irregular surface of the permanent magnets increases the surface roughness of the surface-mounted rotor, increases the wind friction loss and wind noise during motor operation, and affects the operation efficiency of the motor.

[0005] Chinese invention patent application No. CN202122964560.7 discloses a permanent magnet motor rotor skew pole. The V-shaped skew pole structure is used to reduce the harmonic content of the air gap magnetic field, reduce the cogging torque and torque fluctuation, achieve the purpose of reducing motor vibration and noise, and the symmetrical design can weaken the axial reaction force at both ends of the rotor to ensure mechanical reliability. However, the V-shaped skew pole is formed by stacking multiple rotors, which is difficult to implement, and the precision of the surface and inner hole of the stacked rotor is poor, which is prone to cause radial imbalance. Summary of the Invention

[0006] The present invention addresses the shortcomings of existing technologies by proposing a hybrid permanent magnet structure design method to reduce the vibration of permanent magnet motors. This structure can effectively improve the vibration performance of the motor and reduce electromagnetic torque pulsation during motor operation.

[0007] To improve the vibration performance of the motor, this invention employs the following technical solution: a hybrid permanent magnet structure design method for reducing the vibration of a permanent magnet motor, the specific steps of which are as follows:

[0008] Step 1: Determine the dimensional parameters of the traditional permanent magnet motor, including the slot-pole ratio, stator inner and outer diameters, stator-rotor air gap length, pole arc coefficient and thickness of the traditional permanent magnet;

[0009] Step 2: Use the finite element method to solve the electromagnetic force of the traditional permanent magnet motor and perform harmonic analysis to determine the main vibration order and permanent magnet magnetic flux density harmonic order that cause motor vibration.

[0010] Step 3: Based on the motor size parameters, determine the hybrid permanent magnet structure model, the number of hybrid permanent magnet blocks, and the types of permanent magnets;

[0011] Step 4: Construct the magnetomotive force expression of the hybrid permanent magnet structure using analytical methods, and perform harmonic analysis on the magnetomotive force of the hybrid permanent magnet structure using numerical methods.

[0012] Step 5: Use a multi-objective genetic algorithm to reduce the harmonic content of the permanent magnet magnetomotive force and determine the parameters of various variables in the hybrid permanent magnet structure;

[0013] Step 6: Import the optimized hybrid permanent magnet structure model into the finite element software for simulation to calculate the permanent magnet magnetic flux density harmonics and electromagnetic force harmonics.

[0014] Step 7: Couple the three-dimensional model of the motor with the electromagnetic model in finite element software using multiphysics to perform motor vibration analysis, obtain the vibration results of the hybrid permanent magnet structure, and verify the effectiveness of the present invention.

[0015] Furthermore, in step 1, the motor used is a 48-slot / 8-pole permanent magnet synchronous motor, which includes four parts: stator, winding, permanent magnet, and rotor; the winding structure is a single-layer modular double-three configuration with a mutual difference of 30°; and the permanent magnet of the traditional structure adopts samarium cobalt permanent magnet SmCo32.

[0016] Furthermore, in step 2, the main vibrations of the motor are the second-order vibration at the 6th harmonic and the zero-order vibration at the 12th harmonic; the vibration at the 12th harmonic is mainly generated by the interaction of the 4th and 44th harmonics of the permanent magnet fundamental wave, the 12th and 36th harmonics of the permanent magnet, and the 20th and 28th harmonics of the permanent magnet; the second-order vibration at the 6th harmonic is mainly generated by the interaction of the 20th harmonic of the permanent magnet with the 26th and 30th harmonics of the armature, and the 28th harmonic of the permanent magnet with the 26th harmonic of the armature.

[0017] Furthermore, in step 3, the hybrid permanent magnet structure used consists of a high remanence SmCo32 permanent magnet in the middle (1.13T) and low remanence SmCo24 permanent magnets on both sides (1.01T). The hybrid permanent magnets are glued together before magnetization, and the hybrid permanent magnets are magnetized in parallel with a maximum remanence of 1.13T.

[0018] Furthermore, in step 4, the expression for the magnetization length of the permanent magnet with the hybrid permanent magnet structure is l. c for:

[0019]

[0020] Among them l c R is the magnetization length of the permanent magnet; R is the outer radius of the permanent magnet; θ is the angle of change of the hybrid permanent magnet; h pm α is the height of the permanent magnet; p is the polar arc coefficient; p is the polar pair number.

[0021] Furthermore, in step 4, the magnetomotive force expression F of the permanent magnet with a hybrid permanent magnet structure is calculated. c for:

[0022]

[0023] Where F c Calculate the magnetomotive force for a permanent magnet with a hybrid permanent magnet structure; θ c1 The angle of the intermediate permanent magnet; H c1 H represents the magnetic field strength of the intermediate permanent magnet. c2 The magnetic field strength of the permanent magnets on both sides.

[0024] Furthermore, in step 5, the optimization variable for the multi-objective genetic algorithm is determined to be the hybrid permanent magnet pole arc coefficient α. p θ, the angle of the intermediate permanent magnet c1 and permanent magnet height h pm The algorithm determines the range of variation for each variable based on the hybrid permanent magnet structure; the optimization objective of the multi-objective genetic algorithm is the 20th harmonic of the hybrid permanent magnet magnetic flux density. 20th And 28 times B 28th Minimum amplitude, average electromagnetic torque T avg maximum.

[0025] Furthermore, in step 5, a correlation analysis is performed on the optimization variable parameters and the optimization target parameters of the multi-objective genetic algorithm, and the sensitivity of the optimization variable parameters is determined according to formula (3).

[0026]

[0027] Where S ni To calculate sensitivity, f is the response of the target parameter, and z i To optimize the values ​​of variable parameters.

[0028] Furthermore, in step 5, sample points are determined by the central experimental design (BBD) method, and the optimized target values ​​of the sample points are obtained by analytical method and finite element simulation; the second-order response surface regression surrogate model of each optimized target parameter is obtained, as shown in formula (4), and the accuracy of the surrogate model is verified.

[0029]

[0030] Where Y is the optimization objective parameter, β0, β j ,β jj and β ij These are the second-order response surface regression coefficients, X i and X j It involves optimizing variable parameters.

[0031] Furthermore, in step 5, the obtained second-order response surface regression surrogate model is subjected to deep optimization using a multi-objective genetic algorithm to obtain the Pareto solution set.

[0032] Furthermore, in step 5, the Pareto solution optimization result is substituted into the analytical expression, and the magnetomotive force harmonics of the permanent magnet are calculated using a numerical method to determine the optimal hybrid permanent magnet structure model.

[0033] Furthermore, in step 6, the determined hybrid permanent magnet structure model is imported into finite element software for simulation analysis to obtain permanent magnet magnetic flux density harmonics, electromagnetic force harmonics, and average electromagnetic torque.

[0034] Furthermore, in step 7, the three-dimensional model of the motor and the electromagnetic model are subjected to multiphysics coupling simulation analysis in finite element software to obtain the vibration acceleration on the surface of the motor housing.

[0035] Based on the traditional permanent magnet motor, a finite element simulation model is constructed. The air gap magnetic flux density harmonics and electromagnetic force density harmonics of the motor are solved by finite element software. The main electromagnetic force order causing motor vibration is determined, the main magnetic flux density harmonic order causing motor vibration is identified, and the permanent magnet magnetic flux density harmonics that need to be weakened are determined.

[0036] In order to ensure the attenuation of permanent magnet magnetic flux density harmonics, and to consider the feasibility of processing, the structure of the hybrid permanent magnet is determined, and the type of permanent magnet and the magnetization method used in the hybrid permanent magnet are specified.

[0037] After determining the structure and magnetization method of the hybrid permanent magnet, an expression for the magnetization length of the hybrid permanent magnet is constructed using analytical methods. Furthermore, after determining the type of permanent magnet used, an expression for the calculated magnetomotive force of the hybrid permanent magnet is constructed in conjunction with the magnetization length of the hybrid permanent magnet.

[0038] After obtaining the expression for calculating the magnetomotive force of the hybrid permanent magnet, the optimization variables of the hybrid permanent magnet structure are clarified. At the same time, the optimization objective of the multi-objective genetic algorithm is clarified by combining the permanent magnet magnetic flux density harmonics that need to be weakened.

[0039] After determining the structure of the hybrid permanent magnet, the range of variation of the optimization variables is determined based on the structural characteristics. Correlation analysis between the optimization variables and the optimization objective is conducted to determine the sensitivity of the optimization variables to the optimization objective. The optimization variables with high sensitivity are selected as the final optimization variables.

[0040] After determining the optimization variables and their range, the central experimental design (BBD) method is used to determine the sample points for the multi-objective genetic algorithm, reducing the impact of excessively large sample points caused by parameter scanning. The determined sample points are then analyzed to obtain the optimization target values ​​for the sample points.

[0041] The second-order response surface regression surrogate model for each optimization objective parameter is calculated based on the sample point results. The accuracy of the surrogate model is verified by the sample point method. The Pareto solution set of the second-order response surface surrogate model is calculated by a multi-objective genetic algorithm and substituted into the analytical model to determine the optimal value of the optimization variable.

[0042] After obtaining the optimal variable values, an optimal model of the hybrid permanent magnet structure is constructed and imported into finite element software for simulation analysis. The results of permanent magnet magnetic flux density harmonics, electromagnetic torque and vibration acceleration are compared with the results of traditional permanent magnet structures to verify the effectiveness of the invention.

[0043] The present invention has the following benefits:

[0044] 1. In this invention, the permanent magnet motor adopts a hybrid permanent magnet structure, which can significantly reduce the vibration during motor operation and improve the stability of the motor.

[0045] 2. This invention reduces the vibration of permanent magnet motors and simultaneously reduces electromagnetic torque pulsation, thereby improving the electromagnetic performance of the motor.

[0046] 3. The present invention adopts a hybrid permanent magnet structure method, which is easy to implement and highly applicable, and can solve the limitations of traditional methods.

[0047] In summary, the hybrid permanent magnet structure design method for reducing the vibration of a permanent magnet motor according to the present invention can not only reduce the vibration of the permanent magnet motor and improve its vibration performance, but also reduce electromagnetic torque pulsation and improve its electromagnetic performance, thus solving the limitations of traditional methods. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of a traditional permanent magnet motor structure;

[0049] Figure 2 This is a schematic diagram of the hybrid permanent magnet motor structure of the present invention;

[0050] Figure 3 A comparison diagram of the radial air gap magnetic flux density harmonics of the permanent magnet magnetic field between a conventional permanent magnet structure motor and a hybrid permanent magnet structure motor according to an embodiment of the present invention;

[0051] Figure 4 A comparison diagram of the vibration acceleration of the housing surface of a traditional permanent magnet structure motor and a hybrid permanent magnet structure motor according to an embodiment of the present invention;

[0052] Figure 5 A comparison diagram of the electromagnetic torque of a traditional permanent magnet structure motor and a hybrid permanent magnet structure motor according to an embodiment of the present invention;

[0053] Figure 6 This is a flowchart illustrating the design process of the hybrid permanent magnet structure motor of this invention. Detailed Implementation

[0054] To illustrate the design method and benefits of the present invention in more detail, specific embodiments and related drawings will be used for explanation.

[0055] Figure 1 This is a schematic diagram of a traditional permanent magnet motor. The motor is a 48-slot, 8-pole, single-layer surface-mount permanent magnet motor with a modular double-triple winding configuration, 30° apart. Here, 1 represents the stator core, 2 represents the armature winding, 3 represents the permanent magnet, 4 represents the rotor core, 6 indicates the permanent magnet type is SmCo32 (samarium cobalt), 8 represents the permanent magnet height, and 10 represents the permanent magnet pole arc coefficient. A finite element model was constructed based on the traditional permanent magnet motor structure, and simulation analysis was performed. It was determined that the main vibrations of the motor are the second-order vibration at the 6th harmonic and the zero-order vibration at the 12th harmonic. The vibration at the 12th harmonic is mainly caused by the interaction of the 4th and 44th harmonics of the permanent magnet fundamental wave, the 12th and 36th harmonics of the permanent magnet, and the 20th and 28th harmonics of the permanent magnet. The second-order vibration at the 6th harmonic is mainly caused by the interaction of the 20th harmonic of the permanent magnet with the 26th and 30th harmonics of the armature, and the 28th harmonic with the 26th harmonic of the armature.

[0056] Figure 2This is a schematic diagram of an embodiment of the hybrid permanent magnet structure of the present invention. In the diagram, 5 represents the type of permanent magnet on the left (SmCo24), 7 represents the type of permanent magnet on the right (SmCo24), 9 represents the angle of the middle permanent magnet, and the magnetization method is parallel magnetization. Based on this diagram, the expression for the magnetization length of the permanent magnets in the hybrid permanent magnet structure can be derived. c for:

[0057]

[0058] Among them l c R is the magnetization length of the permanent magnet; R is the outer radius of the permanent magnet; θ is the angle of change of the hybrid permanent magnet; h pm α is the height of the permanent magnet; p is the polar arc coefficient; p is the polar pair number.

[0059] By combining the magnetization length and the magnetic field strength of the permanent magnet, the expression for calculating the magnetomotive force F of a hybrid permanent magnet structure can be derived. c for:

[0060]

[0061] Where F c Calculate the magnetomotive force for a permanent magnet with a hybrid permanent magnet structure; θ c1 The angle of the intermediate permanent magnet; H c1 H represents the magnetic field strength of the intermediate permanent magnet. c2 The magnetic field strength of the permanent magnets on both sides.

[0062] Since the air gap magnetic flux density of a permanent magnet is the product of the magnetomotive force (MTF) of the permanent magnet and the air gap permeability, and the permeability of the permanent magnet and the air gap are essentially the same, the parameters of the permanent magnet have little effect on the air gap permeability. In other words, the air gap magnetic flux density is positively correlated with the magnetomotive force (MTF). Based on the expression for calculating the MMF of a permanent magnet, the variable affecting the air gap magnetic flux density can be determined; therefore, the optimization variable for the multi-objective genetic algorithm is the hybrid permanent magnet pole arc coefficient α. p θ, the angle of the intermediate permanent magnet c1 and permanent magnet height h pm The variation range of each variable was determined by combining the hybrid permanent magnet structure; based on the analysis of traditional permanent magnet motors, the optimization objective of the multi-objective genetic algorithm can be determined as the 20th harmonic of the hybrid permanent magnet magnetic flux density. 20th And 28 times B 28th Minimum amplitude, average electromagnetic torque T avg maximum.

[0063] After determining the variables and objectives of the multi-objective optimization, the correlation analysis between the optimization variables and the optimization objectives is performed according to formula (3) to determine the sensitivity of each variable to the optimization objectives.

[0064]

[0065] Where S ni To calculate sensitivity, f is the response of the target parameter, and z i To optimize the variable parameter values, the results show that the selected optimization variable, the hybrid permanent magnet pole arc coefficient α, is optimal. p θ, the angle of the intermediate permanent magnet c1 and permanent magnet height h pm All of the target parameters are highly sensitive parameters. Then, the central experimental design BBD method is used to determine the sample points, and the target values ​​of the sample points are obtained by analytical method and finite element simulation. The second-order response surface regression surrogate model of each target is obtained, as shown in formula (4), and the accuracy of the surrogate model is verified by the sample point method.

[0066]

[0067] Where Y is the optimization objective parameter, β0, β j ,β jj and β ij These are the second-order response surface regression coefficients, X i and X j These are optimization variables. The average electromagnetic torque T was calculated. avg The second-order response surface regression surrogate model is shown in Equation (5), and the 20th harmonic of the permanent magnet magnetic flux density is B. 20th The second-order response surface regression surrogate model is shown in Equation (6), and the 28th harmonic of the permanent magnet magnetic flux density is B. 28th The second-order response surface regression surrogate model is shown in Equation (7).

[0068]

[0069]

[0070]

[0071] After determining the second-order response surface regression surrogate model, a multi-objective genetic algorithm is used for deep optimization to obtain the Pareto solution set. A suitable optimization result is selected from the Pareto solution set and substituted into the analytical expression for calculating the magnetomotive force of the permanent magnet. The magnetomotive force harmonics of the permanent magnet are calculated using a numerical method, and the electromagnetic force harmonics are calculated using finite element software. The optimal hybrid permanent magnet structure model is the model of the embodiment of this invention.

[0072] Figure 3The figure shows a comparison of the radial air gap magnetic flux density harmonics of the permanent magnet magnetic field between a traditional permanent magnet structure motor and a hybrid permanent magnet structure motor according to the present invention. As can be seen from the figure, after adopting the hybrid permanent magnet structure, the amplitudes of the 20th and 28th harmonics of the radial air gap magnetic flux density of the permanent magnet magnetic field that affect motor vibration are significantly reduced, and the amplitude of the 12th harmonic of the radial air gap magnetic flux density of the permanent magnet magnetic field is also reduced.

[0073] Figure 4 The figure shows a comparison of the vibration acceleration of the housing surface of a traditional permanent magnet structure motor and a hybrid permanent magnet structure motor according to the present invention. As can be seen from the figure, after adopting the hybrid permanent magnet structure, the vibration acceleration of the motor at the 6th and 12th harmonics is significantly reduced. At the same time, the vibration acceleration at other frequencies is also lower than that of the traditional permanent magnet structure motor. Therefore, the hybrid permanent magnet structure provides a more comprehensive improvement to motor vibration.

[0074] Figure 5 The graph shows a comparison of the electromagnetic torque of a conventional permanent magnet structure motor and a hybrid permanent magnet structure motor according to the present invention. As can be seen from the graph, after adopting the hybrid permanent magnet structure, the torque ripple of the electromagnetic torque is reduced from 3.74% in the conventional permanent magnet structure to 1.39%, demonstrating a significant optimization effect, while the average electromagnetic torque remains essentially unchanged. Therefore, adopting the hybrid permanent magnet structure can not only improve the vibration performance of the motor but also improve its electromagnetic torque performance, verifying the effectiveness of the present invention.

[0075] Figure 6 This is a flowchart illustrating the design process of the hybrid permanent magnet structure motor of this invention. The design mainly includes three stages: hybrid permanent magnet structure design, multi-objective optimization, and finite element verification. Hybrid permanent magnet structure design is the primary method for improving the harmonics of the permanent magnet magnetic field in the motor; multi-objective optimization is the main technical means for determining the hybrid permanent magnet structure parameters; and finite element verification ensures the effectiveness of the implementation results. Among the hybrid permanent magnet structure parameters, the pole arc coefficient α... p θ, the angle of the intermediate permanent magnet c1 and permanent magnet height h pm The choice of [aspect name] has a significant impact on the harmonic content of the permanent magnet field and needs to be determined using the finite element method.

[0076] In summary, this invention provides a hybrid permanent magnet structure design method for reducing vibration in permanent magnet motors. First, the parameters of a traditional permanent magnet motor are determined, and finite element simulation analysis is performed to analyze the main vibrations and the main magnetic flux density harmonic orders causing these vibrations. Then, the basic model of the hybrid permanent magnet structure is determined, and the magnetization length and magnetomotive force expressions for the hybrid permanent magnet structure are derived. The optimization variables of the hybrid permanent magnet structure are clarified, and a multi-objective genetic algorithm is used to optimize and determine the parameters of the hybrid permanent magnet structure. Finally, the determined hybrid permanent magnet structure model is imported into finite element software for simulation, calculating the radial air gap magnetic flux density harmonics of the permanent magnet magnetic field, the vibration acceleration of the casing surface, and the electromagnetic torque. This verifies that the hybrid permanent magnet structure of this invention has the ability to improve vibration and electromagnetic performance. This invention can provide a reference for reducing motor vibration and torque ripple.

Claims

1. A method for designing a hybrid permanent magnet structure to reduce vibration of a permanent magnet motor, characterized in that, The specific steps are as follows: Step 1: Determine the dimensional parameters of the traditional permanent magnet motor, including the slot-pole ratio, stator inner and outer diameters, stator-rotor air gap length, and the pole arc coefficient and thickness parameters of the traditional permanent magnet. Step 2: Model the traditional motor, simulate the model using the finite element method, solve the electromagnetic force and perform harmonic analysis to determine the main vibration order and permanent magnet flux density harmonic order that cause motor vibration. Step 3: Based on the motor size parameters, determine the hybrid permanent magnet structure model, the number of hybrid permanent magnet blocks, and the types of permanent magnets; Step 4: Construct the magnetomotive force expression of the hybrid permanent magnet using analytical methods, and perform harmonic analysis on the magnetomotive force of the hybrid permanent magnet structure using numerical methods. In step 4, the expression for the magnetization length of the permanent magnet in the hybrid permanent magnet structure is l. c for: (1)； Among them l c R is the magnetization length of the permanent magnet; R is the outer radius of the permanent magnet; θ is the angle of change of the hybrid permanent magnet; h pm α is the height of the permanent magnet; p p is the polar arc coefficient; p is the polar pair number; In step 4, the magnetomotive force expression F of the hybrid permanent magnet structure is calculated. c for: (2)； Where F c Calculate the magnetomotive force for a permanent magnet with a hybrid permanent magnet structure; θ c1 The angle of the intermediate permanent magnet; H c1 H represents the magnetic field strength of the intermediate permanent magnet. c2 The magnetic field strength of the permanent magnets on both sides; Step 5: Use a multi-objective genetic algorithm to reduce the harmonic content of the permanent magnet magnetomotive force and determine the parameters of various variables in the hybrid permanent magnet structure; Step 6: Import the optimized hybrid permanent magnet structure model into the finite element software for simulation to calculate the permanent magnet magnetic flux density harmonics and electromagnetic force harmonics. Step 7: Couple the three-dimensional model of the motor with the electromagnetic model in finite element software using multiphysics to perform motor vibration analysis, obtain the vibration results of the hybrid permanent magnet structure, and verify the effectiveness of the present invention.

2. The hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor according to claim 1, characterized in that, In step 1, the motor used is a 48-slot / 8-pole permanent magnet synchronous motor, which includes four parts: stator, winding, permanent magnet, and rotor. The outermost layer is the stator, and the stator slots contain the winding. The innermost layer is the rotor, and the permanent magnet is bonded to the outer surface of the rotor. The winding structure is a single-layer modular double-three configuration with a 30° mutual difference. The permanent magnet in the traditional structure uses samarium cobalt permanent magnet SmCo32.

3. The hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor according to claim 1, characterized in that, In step 2, the main vibrations of the motor are the second-order vibration at the 6th harmonic and the zero-order vibration at the 12th harmonic. The zero-order vibration at the 12th harmonic is mainly generated by the interaction of the 4th and 44th harmonics of the permanent magnet fundamental wave, the 12th and 36th harmonics of the permanent magnet, and the 20th and 28th harmonics of the permanent magnet. The second-order vibration at the 6th harmonic is mainly generated by the interaction of the 20th harmonic of the permanent magnet with the 26th and 30th harmonics of the armature, and the 28th harmonic of the permanent magnet with the 26th harmonic of the armature.

4. The hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor according to claim 1, characterized in that, In step 3, the hybrid permanent magnet structure used consists of a high remanence SmCo32 permanent magnet in the middle (1.13T) and low remanence SmCo24 permanent magnets on both sides (1.01T). The hybrid permanent magnets are glued together before magnetization and then magnetized in parallel with the maximum remanence of 1.13T.

5. The hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor according to claim 1, characterized in that, In step 5, the optimization variable for the multi-objective genetic algorithm is determined to be the hybrid permanent magnet polar arc coefficient α. p θ, the angle of the intermediate permanent magnet c1 and permanent magnet height h pm The algorithm determines the range of each optimization variable based on the hybrid permanent magnet structure; the optimization objective of the multi-objective genetic algorithm is the 20th harmonic of the hybrid permanent magnet magnetic flux density. 20th And 28 times B 28th Minimum amplitude, average electromagnetic torque T avg maximum.

6. The hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor according to claim 1, characterized in that, In step 5, the correlation analysis between the optimization variable parameters and the optimization target parameters of the multi-objective genetic algorithm is performed, and the sensitivity of the optimization variable parameters is determined according to formula (3). (3)； Where S ni To calculate sensitivity, f is the response of the target parameter, and z i To optimize the values ​​of variable parameters.

7. The hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor according to claim 1, characterized in that, Step 5 also includes determining sample points through the central experimental design BBD method, obtaining the optimized target values ​​of the sample points using analytical methods and finite element simulation; obtaining the second-order response surface regression surrogate model of each optimized target parameter, as shown in formula (4), and verifying the accuracy of the surrogate model. (4)； Where Y is the optimization objective parameter, β0, β j ,β jj and β ij These are the second-order response surface regression coefficients, X i and X j It optimizes variable parameters; The desired second-order response surface regression surrogate model is deeply optimized using a multi-objective genetic algorithm to obtain the Pareto solution set; Substituting the Pareto solution set optimization results into the analytical expression, the harmonics of the magnetomotive force of the hybrid permanent magnet are calculated using a numerical method to determine the optimal hybrid permanent magnet structural model.

8. The hybrid permanent magnet structure design method for reducing vibration of a permanent magnet motor according to claim 1, characterized in that, In step 6, the determined hybrid permanent magnet structure model is imported into finite element software for simulation analysis to obtain permanent magnet magnetic flux density harmonics, electromagnetic force harmonics, and average electromagnetic torque; in step 7, the three-dimensional model of the motor and the electromagnetic model are subjected to multiphysics coupling simulation analysis in finite element software to obtain the vibration acceleration on the surface of the motor housing.

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