A Method for Suppressing Vibration and Noise of Bearingless Switched Reluctance Motors

Abstract

A method for suppressing vibration and noise of a bearingless switched reluctance motor. The 12 / 8-pole BSRMWR includes a double salient stator and rotor and an asymmetric half-bridge power converter composed of 12 sets of windings. Due to its body structure and asymmetric power supply method, the motor has relatively large vibration and noise. The shape optimization method is to establish a dynamic optimization model and perform iterative optimization on the BSRMWR motor housing. When the termination condition is met, the finally output motor housing model after iterative optimization is obtained. The modal strain energy of the BSRMWR housing before and after optimization is obtained through finite element modal analysis. The modal strain energy can accurately reflect the change of the actual local force on the motor housing and effectively analyze the stiffness of the motor housing. The present invention takes improving the stiffness of the motor housing as the optimization design goal, the vibration deformation amount of the motor as the design variable, and the mass of the motor housing as the constraint function. The main optimization scheme is to use the shape optimization method to find the optimal rib distribution in the motor housing and compare the vibration and noise waveforms of the motor before and after optimization.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor vibration and noise, and particularly relates to a method for suppressing vibration and noise of a bearingless switched reluctance motor. Background Technique

[0002] The technology of vibration reduction and noise reduction has always been an important topic in the field of engineering design. Morphology optimization is a method for optimizing the structure shape, and its main optimization scheme is to find the optimal distribution of stiffeners in plate and shell structures. There are three elements in this optimization design, namely design variables, objective function, and constraint conditions. Design variables are a set of parameters that change during the optimization process to improve performance; the objective function is the required optimal design performance and is a function of the design variables; the constraint conditions are the limitations on the design.

[0003] Currently, in the field of motor vibration reduction and noise reduction, it is nothing more than considering from the perspective of control strategies and structural optimization. A large number of literatures have conducted relevant research on suppressing motor vibration and noise from the perspective of control strategies. From the perspective of structural optimization, for example, many literatures have carried out optimization analysis starting from aspects such as motor stator / rotor slotting and skewed poles. Although it can bring certain vibration reduction and noise reduction effects, this method does not have universality and processability, and if not handled well, it will damage the electrical characteristics of the motor and bring counterproductive effects. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for suppressing vibration and noise of a bearingless switched reluctance motor. By optimizing the morphology of the motor housing, the final optimized model of the motor stiffeners is obtained. While ensuring the electrical characteristics of the motor, its vibration and noise are effectively reduced.

[0005] The present invention provides a method for suppressing vibration and noise of a bearingless switched reluctance motor, including the following steps,

[0006] Step S1. Perform finite element mesh division, define the model material, thickness, and connection, and establish a finite element model of the motor stator-housing structure;

[0007] Step S2. Solve the free mode of the motor housing model, calculate the first N-order modes, and then obtain the initial frequency before optimization through the mode magnitude and vibration mode;

[0008] Step S3. Perform mid-surface extraction on the motor housing to obtain the finite element model of the motor housing, and then obtain the initial frequency before optimization through the mode magnitude and vibration mode;

[0009] Step S4. Improve the stiffness of the motor housing through morphology optimization, with the first-order modal frequency as the optimization target;

[0010] Step S5. Taking the deformation of the motor housing as the design variable and the mass of the motor housing as the constraint condition, a structural dynamics optimization model is established;

[0011] Step S6. The topography optimization area is the BSRMWR motor housing. In engineering, the rib width is 1.5 - 2 times the average size of the grid cells, and the rib angle is 60° - 75°;

[0012] Step S7. Perform optimization calculations on the optimization model. After a finite number of iterations, if convergence is achieved, the optimization ends; otherwise, return to Step S4 - Step S6

[0013] Step S8. Process the ribs after topography optimization according to the feasibility and experience of the production process. For the optimized ribs, use tools to convert the optimization cloud map into a surface;

[0014] Step S9. Perform free modal analysis on the optimized model again to obtain the frequencies and vibration modes of the optimized structure;

[0015] Step S10. Compare the modal vibration modes and frequency magnitudes before and after optimization. If the optimized mode reaches the defined target value, the analysis is completed; if the optimized mode does not reach the defined target value, return to Step S4 - Step S6 to continue the topography optimization analysis.

[0016] As a further technical solution of the present invention, in Step S5, taking mass lightweighting as the constraint condition and the deformation of the motor housing as the design variable; then the model is:

[0017] Minimize:

[0018] f(X) = f(x1, x2, …, x n )

[0019] Constraint conditions:

[0020] g j (X) ≤ 0 (j = 1, 2, …, m)

[0021] h k (X) ≤ 0 (k = 1, 2, …, m k )

[0022]

[0023] Among them, X = (x1, x2, …, x n ) is the topography optimization design variable, f(X) is the objective function, g(X) and h(X) are inequality constraints, is the upper limit of the variable, is the lower limit of the variable.

[0024] Further, in step S6, the rib width is 4 mm, the rib angle is 60°, and the rib height is 3 mm.

[0025] Further, in step S1, when the motor model is meshed, the stator uses solid element meshes, and the housing uses shell element meshes. The element mesh size is determined according to the geometric dimensions and accuracy requirements of the motor. The material of the motor stator is steel, and the material of the housing is iron.

[0026] Further, in step S5, the modal file before optimization is output in HyperWorks and imported into the vibration and noise analysis software to perform modal-based vibration analysis and acoustic response analysis on the motor model before optimization.

[0027] The advantages of the present invention are as follows: By analyzing the strain energy of the motor housing and the vibration and noise response, the distribution of the stiffeners on the motor housing is optimized, and finally a reasonable shape arrangement of the stiffeners is obtained. Different from topology optimization, shape optimization does not delete materials, but generates ribs according to the perturbation of nodes in the designable area, which has strong engineering application value for suppressing vibration and noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic flow chart of the method of the present invention;

[0029] Figure 2 is the finite element model of BSRMWR before optimization of the present invention

[0030] Figure 3 are the vibration displacement response and acoustic response of BSRMWR before optimization of the present invention

[0031] Figure 4 is the motor housing of BSRMWR after shape optimization of the present invention

[0032] Figure 5 is the model of BSRMWR after optimization of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Please refer to Figure 1 , this embodiment provides the present invention, which includes the following steps:

[0034] S1. Establishment of the motor model:

[0035] After three-dimensional solid modeling of the motor in SolidWorks according to the main parameters of the 12 / 8 pole BSRMWR prototype, it is imported into HyperWorks in x_t format or step format;

[0036] S2. Construction of the finite element model:

[0037] When meshing the motor model, solid element meshes are used for the stator and shell element meshes are used for the housing. The element mesh size is determined according to the geometric dimensions and accuracy requirements of the motor. The material of the motor stator is steel and the material of the housing is iron. Elastic modulus, Poisson's ratio, density and other properties are assigned to establish the finite element model for modal analysis of the motor as shown in Figure 2 ;

[0038] S3. Conduct free modal calculation:

[0039] Perform free modal solution on the BSRMWR motor stator-housing model, calculate the first N modes, and view the modal results in the post-processing software, including modal vibration modes and modal frequencies. It is found that the modal frequencies of the motor model are not high, that is, the structural stiffness needs to be improved;

[0040] S4. Free modal calculation of the motor housing:

[0041] Perform mid-surface extraction on the motor housing to obtain the finite element model of the motor housing. Calculate and output the modal strain energy contour map of the motor housing, and then view the modal magnitude and vibration mode in the post-processing software to obtain the initial frequency before optimization;

[0042] S5. Vibration and noise calculation of the motor before optimization:

[0043] Output the modal file before optimization in HyperWorks, import it into the vibration and noise analysis software, perform modal-based vibration analysis and acoustic response analysis on the motor model before optimization, and the output results are as shown in Figure 3 ;

[0044] S6. Design the topography optimization model:

[0045] The mathematical model of structural topography optimization design consists of three parts: design variables, objective function and constraint conditions. Its mathematical model can be expressed as follows:

[0046] Minimize:

[0047] f(X) = f(x1, x2,..., x n )

[0048] Constraint conditions:

[0049] g j (X) ≤ 0 j = 1, 2,..., m

[0050] h k (X) ≤ 0 k = 1, 2,..., m k

[0051]

[0052] Among them, X = (x1, x2,..., x n$X$ is the design variable for shape optimization, $f(X)$ is the objective function, $g(X)$ and $h(X)$ are the inequality constraints, is the upper limit of the variable, is the lower limit of the variable.

[0053] S7. Define the objective of the motor shape optimization design:

[0054] Adopt the shape optimization scheme to improve the stiffness of the motor housing. When the first-order modal frequency is increased, the subsequent modal frequencies will also increase accordingly. Therefore, the first-order modal frequency is used as the optimization design objective here;

[0055] S8. Define the design variables and constraint conditions of the motor shape optimization:

[0056] Take the deformation of the motor housing as the design variable and the mass of the motor housing as the constraint condition to establish a structural dynamics optimization model;

[0057] S9. Define the shape optimization region and rib parameters of the motor:

[0058] The shape optimization region is the BSRMWR motor housing. In engineering, the rib width is generally set to 1.5 - 2 times the average size of the grid unit, and the rib angle is usually set to 60° - 75°. Therefore, the rib width is taken as 4 mm, the rib angle is taken as 60°, and the rib height is taken as 3 mm here.

[0059] S10. Solve the shape optimization:

[0060] After all the parameters are set, perform the optimization calculation on the optimization model. After a finite number of iterations, if it converges, the optimization ends, and the motor housing after shape optimization is calculated and output, as Figure 4 shown. Otherwise, return to step S7 - step S9 to redesign the optimization scheme;

[0061] S11. Process the shape optimization results:

[0062] Combined with the feasibility and experience of the production process, process the ribs after shape optimization. Use tools to convert the optimization nephogram into a surface for the optimized ribs, as Figure 5 shown;

[0063] S12. Verify the feasibility of the shape optimization results:

[0064] Perform the free modal analysis on the optimized model again to obtain the frequencies and vibration modes of the optimized structural modes;

[0065] S13. Evaluate the performance of the shape optimization results:

[0066] Compare the modal shapes and frequencies before and after optimization. If the modal frequency after optimization reaches the defined target value, the analysis is completed. If the defined target value is not reached after optimization, return to steps S6 to S9 to continue the topography optimization analysis;

[0067] S14. Calculation of motor vibration and noise after optimization:

[0068] Perform finite element modal solution on the optimized model, export the modal file, and then re-import the optimized modal file into the vibration and noise analysis software to calculate the vibration displacement response and acoustic response of the motor. Through comparative analysis, illustrate the feasibility of the optimization scheme.

[0069] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above specific embodiments. The above specific embodiments and the descriptions in the specification are only for further explaining the principles of the present invention. Without departing from the spirit scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the claims and their equivalents.

Claims

1. A method for suppressing vibration and noise of a bearingless switched reluctance motor, characterized in that, It includes the following steps. Step S1. Conduct finite element mesh division, define the model materials, thickness, and connections, and establish a finite element model of the motor stator-housing structure. Step S2. Perform free modal solution on the motor housing model, calculate the first N-order modes, and then obtain the initial frequency before optimization through the modal magnitude and vibration mode. Step S3. Perform mid-surface extraction on the motor housing to obtain the finite element model of the motor housing, and then obtain the initial frequency before optimization through the modal magnitude and vibration mode. Step S4. Improve the stiffness of the motor housing through topology optimization, with the first-order modal frequency as the optimization target. Step S5. Take the deformation of the motor housing as the design variable and the mass of the motor housing as the constraint condition to establish a structural dynamics optimization model. Step S6. The topology optimization region is the BSRMWR motor housing. In engineering, the rib width is 1.5 - 2 times the average size of the grid element, and the rib angle is 60° - 75°. Step S7. Perform optimization calculation on the optimization model. After a finite number of iterations, if it converges, the optimization ends; otherwise, return to Step S4 - Step S6. Step S8. Process the ribs after topology optimization according to the feasibility and experience of the production process. Use tools to convert the optimization cloud map of the optimized ribs into a surface. Step S9. Perform free modal analysis on the optimized model again to obtain the frequency and vibration mode of the optimized structural mode. Step S10. Compare the modal vibration modes and frequency magnitudes before and after optimization. If the optimized mode reaches the defined target value, the analysis is completed; if the optimized mode does not reach the defined target value, return to Step S4 - Step S6 to continue the topology optimization analysis. In Step S5 above, with mass lightweight as the constraint condition and the deformation of the motor housing as the design variable, the model is as follows: Minimize: f(X) = f(x1, x2, …, x n ) Constraint condition: g j (X) ≤ 0 for j = 1, 2, …, m h k (X) ≤ 0 for k = 1, 2, …, m k Among them, X = (x1, x2, …, x n ) is the design variable for morphology optimization, f(X) is the objective function, g(X) and h(X) are the inequality constraints, is the upper limit of the variable, is the lower limit of the variable.

2. The method for suppressing vibration and noise of a bearingless switched reluctance motor according to claim 1, characterized in that, In Step S6 above, the rib width is 4 mm, the rib angle is 60°, and the rib height is 3 mm.

3. The method for suppressing vibration and noise of a bearingless switched reluctance motor according to claim 1, characterized in that, In Step S1 above, when performing mesh division on the motor model, solid element meshes are used for the stator and shell element meshes are used for the housing. Determine the element mesh size according to the geometric dimensions and accuracy requirements of the motor. The material of the motor stator is steel, and the material of the housing is iron.

4. The method for suppressing vibration and noise of a bearingless switched reluctance motor according to claim 1, characterized in that, In Step S5 above, output the modal file before optimization in HyperWorks, import it into the vibration and noise analysis software, and perform modal-based vibration analysis and acoustic response analysis on the motor model before optimization.

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