A method and device for predicting air gap variation of a permanent magnet synchronous motor

Abstract

This invention relates to the field of automotive technology, specifically to a method and device for predicting air gap changes in permanent magnet synchronous motors. It includes the following steps: Step 1, establishing a finite element assembly model of the entire permanent magnet synchronous motor; Step 2, determining the load parameters; Step 3, after establishing the analysis model, performing calculations in finite element analysis software to obtain the deformation difference between the outer ring of the rotor core and the inner ring of the stator core, which is the air gap change value. By summing this value with the total eccentricity, the result is compared with the design air gap value to assess the risk of rotor-stator rubbing. This invention can conveniently consider the motor's operating state, improve prediction accuracy, and is more reasonable.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, specifically to a method and apparatus for predicting changes in the air gap of a permanent magnet synchronous motor. Background Technology

[0002] The air gap between the stator and rotor of a permanent magnet synchronous motor affects the motor's performance and safety. During operation, factors such as rotor eccentricity, impact, and temperature rise can cause the air gap to shrink locally, potentially leading to rotor-stator rubbing and posing a risk of motor failure. An excessively large air gap weakens the air gap magnetic field strength, affecting the motor's output performance. Therefore, it is necessary to calculate the air gap deformation under extreme operating conditions to support motor development. There are generally two methods for obtaining air gap changes: one is experimental detection, typically using sensors placed between the rotor and stator to detect changes in the rotor and stator edge positions. This method requires prototyping the motor, which is time-consuming and costly. The other method is simulation technology, which is efficient and low-cost, but current research in this area is limited, and single-factor simulations have low accuracy due to the numerous factors influencing air gap changes.

[0003] Therefore, a method for predicting air gap changes in permanent magnet synchronous motors is needed to assess air gap design risks and meet development requirements. Summary of the Invention

[0004] This invention provides a method and apparatus for predicting changes in the air gap of a permanent magnet synchronous motor, which can conveniently consider the operating state of the motor, improve the prediction accuracy, and is more reasonable.

[0005] The technical solution of this invention is described below in conjunction with the accompanying drawings:

[0006] In a first aspect, embodiments of the present invention provide a method for predicting changes in the air gap of a permanent magnet synchronous motor, comprising the following steps:

[0007] Step 1: Establish the finite element assembly model of the permanent magnet synchronous motor;

[0008] Step 2: Determine the load parameters;

[0009] Step 3: After establishing the analysis model, perform the calculation in the finite element analysis software to obtain the deformation difference between the outer ring of the rotor core and the inner ring of the stator core, which is the change value of the air gap. By summing it with the total eccentricity σ, the result is compared with the design air gap value to assess the risk of rotor-stator collision.

[0010] Furthermore, the specific method of step one is as follows: the finite element assembly model includes modeling the motor shaft, rotor core, permanent magnet, support bearing, axial wave spring, motor housing, and stator.

[0011] Furthermore, the motor shaft, rotor core, permanent magnet, motor housing, and stator are modeled using solid elements; the support bearing and axial wave spring are simulated using spring elements, and the support stiffness of the support bearing and axial wave spring is calibrated by calibrating the stiffness of the spring elements.

[0012] Furthermore, the support stiffness of the support bearing is divided into axial stiffness and radial stiffness. To simulate the support state of the support bearing during the operation of the permanent magnet synchronous motor, two types of springs, oblique and radial, are used to simulate the bearing balls. The stiffness value of the oblique spring is calculated using the following formula:

[0013] k t =K t ·x1

[0014] In the formula:

[0015] k t —Stiffness value of the inclined spring, in N / mm;

[0016] K t —Bearing radial stiffness, in N / mm;

[0017] x1 — Axial displacement of the bearing inner ring, in mm;

[0018] The stiffness value of the radial spring is obtained by the following formula:

[0019] k r =(K r R1R2-2R2+R1) / (R1-R2)

[0020] In the formula:

[0021] k r —The stiffness value of the radial spring, in N / mm;

[0022] K r —Bearing radial stiffness, in N / mm;

[0023] R1 — Radial displacement of the bearing inner ring under a load of 1N, in mm;

[0024] R2 — Radial displacement of the bearing inner ring under a 2N load, in mm;

[0025] The stiffness of the axial wave spring is obtained by the following formula:

[0026] k = K / n

[0027] In the formula:

[0028] k — simulates the stiffness of a spring, in N / mm;

[0029] K—Axial stiffness parameter of wave spring, unit N / mm;

[0030] n — the number of circumferential springs in the simulated waveform spring;

[0031] The axial wave spring has an initial compression, which is obtained by the following formula:

[0032] Δl=F0 / K

[0033] Δl — Initial compression of the spring, in mm;

[0034] F0—Initial preload of the axial preload device, in N.

[0035] Furthermore, the rotor core and stator simulate stiffness characteristics along different directions by defining the anisotropic properties of the materials.

[0036] Furthermore, the specific method for step two is as follows:

[0037] 21) Identify the main loads affecting air gap changes;

[0038] a. Centrifugal force load generated during high-speed rotor operation;

[0039] b. Unbalanced magnetic pull load caused by rotor eccentricity and uneven air gap;

[0040] c. Eccentric force load generated by the rotor's eccentricity;

[0041] d. The inertial force load generated by impact during the operation of the motor;

[0042] e. Thermal expansion force load generated by the increase in internal temperature of the motor;

[0043] 22) Apply the main loads that affect the air gap change;

[0044] a. Centrifugal force load;

[0045] When the rotor system operates at high speed, the rotor core tends to expand outward due to the centrifugal load. This centrifugal load is applied at the motor's maximum speed.

[0046] ω max =2πn max / 60

[0047] In the formula:

[0048] n max —Maximum motor speed, in r / min;

[0049] ω max—Maximum angular velocity of the motor, in rad / s;

[0050] b. Unbalanced magnetic tensile load;

[0051] When the motor rotor is running, the eccentricity causes an unbalanced magnetic pull. This unbalanced magnetic pull, in turn, increases the rotor eccentricity, resulting in an even greater unbalanced magnetic pull. The specific relationship is as follows:

[0052] σ=σ0+Δσ

[0053] Δσ=F(σ) / K0

[0054] F(σ)=σ·βπDlB 2 / (2αμ0)

[0055] In the formula:

[0056] σ — Total eccentricity, in mm.

[0057] σ0 — Static eccentricity, in mm;

[0058] Δσ — the eccentricity caused by unbalanced magnetic pull, in mm;

[0059] F(σ) — Unbalanced magnetic pull function, in N;

[0060] K0—Support stiffness of the rotor system, N / mm;

[0061] β—Empirical coefficient, taken as 0.5;

[0062] D – Stator inner diameter, in mm;

[0063] l—Core length, in mm;

[0064] B—Average magnetic flux density in the air gap, in tons (T);

[0065] μ0 — Permeability in vacuum, N / A 2 ;

[0066] The formulas for calculating the total eccentricity of the air gap and the unbalanced magnetic pull are obtained as follows:

[0067] σ=σ0·K0 / (K0-λ)

[0068] F(σ)=λσ0·K0 / (K0-λ)

[0069] In the formula, λ=βπDlB 2 / (2αμ0), where the parameters are obtained directly from the parameters of the permanent magnet motor;

[0070] c. Eccentric force load;

[0071] The static eccentric force load generated by the rotor operation is calculated as follows:

[0072]

[0073] In the formula:

[0074] σ0 — Static eccentricity, in mm;

[0075] m—Total rotor mass, in kg;

[0076] The dynamic eccentric force load generated by the rotor operation is calculated as follows:

[0077]

[0078] In the formula:

[0079] m—Total rotor mass, in kg;

[0080] d. Inertial force load;

[0081] When the motor is in an impact condition during operation, an acceleration load 'a' is applied to the rotor system. The magnitude of the load depends on the actual working conditions.

[0082] e. Thermal expansion force load;

[0083] Since the motor experiences temperature rise during operation and the temperature field distribution varies in different parts, different temperature values ​​are assigned to each part based on the motor temperature field test measurement or simulation calculation results.

[0084] Furthermore, the specific method for mitigating the risk of collision and abrasion in step three is as follows:

[0085] If the following formula holds true, there is a risk of collision / grinding:

[0086] (U+σ)·S≥T

[0087] In the formula:

[0088] U—The calculated deformation difference between the outer ring of the rotor core and the inner ring of the stator core, in mm;

[0089] S – Safety factor, greater than 1;

[0090] T – Air gap value, in mm.

[0091] Secondly, embodiments of the present invention provide a stiffness simulation device for modal analysis of a permanent magnet synchronous motor, the device comprising:

[0092] A model building module is used to build a finite element assembly model of the entire permanent magnet synchronous motor.

[0093] The determination module is used to determine the calculated load parameters;

[0094] The judgment module is used to solve the analysis model in the finite element analysis software after the analysis model is established. The deformation difference between the outer ring of the rotor core and the inner ring of the stator core is the change value of the air gap. By summing it with the total eccentricity σ, the result is compared with the design air gap value to assess the risk of collision and rubbing between the rotor and the stator.

[0095] Thirdly, embodiments of the present invention also provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements a prediction method for air gap changes of a permanent magnet synchronous motor as described in any of the embodiments of the present invention.

[0096] Fourthly, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a method for predicting air gap changes in a permanent magnet synchronous motor as described in any of the embodiments of the present invention.

[0097] The beneficial effects of this invention are as follows:

[0098] 1) The air gap change prediction method for permanent magnet synchronous motors proposed in this invention takes into account multiple factors and is consistent with the motor's operating state;

[0099] 2) This invention proposes a simulation method for the bearing support, wave spring and anisotropic material of permanent magnet synchronous motor, which makes the stiffness simulation of the motor more consistent with the actual working conditions and improves the calculation accuracy;

[0100] 3) This invention proposes a calculation method for centrifugal force, eccentric force, unbalanced magnetic pull, inertial force, and temperature load involved in the air gap calculation of permanent magnet synchronous motors, which takes into account the working state of the motor more comprehensively and is more reasonable. Attached Figure Description

[0101] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0102] Figure 1 This is a schematic diagram simulating the stiffness of the angular contact ball bearing in Embodiment 1 of the present invention;

[0103] Figures 2a-2b This is a schematic diagram simulating the stiffness of the waveform spring in Embodiment 1 of the present invention;

[0104] Figure 3This is a flowchart of a method for predicting air gap changes in a permanent magnet synchronous motor, as described in Embodiment 1 of the present invention.

[0105] Figure 4 This is a schematic diagram of the structure of a prediction device for air gap changes in a permanent magnet synchronous motor according to Embodiment 2 of the present invention;

[0106] Figure 5 This is a schematic diagram of the structure of an electronic device according to Embodiment 3 of the present invention. Detailed Implementation

[0107] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0108] Example 1

[0109] Figure 3 This is a flowchart of a method for predicting air gap changes in a permanent magnet synchronous motor according to Embodiment 1 of the present invention. This embodiment can be applied to the prediction of air gap changes in a permanent magnet synchronous motor. The method can be executed by a device for predicting air gap changes in a permanent magnet synchronous motor according to an embodiment of the present invention. The device can be implemented in software and / or hardware.

[0110] A method for predicting air gap changes in permanent magnet synchronous motors includes the following steps:

[0111] Step 1: Establish the finite element assembly model of the permanent magnet synchronous motor;

[0112] The specific method of step one is as follows: The finite element assembly model includes modeling the motor shaft, rotor core, permanent magnet, support bearing, axial wave spring, motor housing, and stator.

[0113] The motor shaft, rotor core, permanent magnet, motor housing, and stator are modeled using solid elements; the support bearing and axial wave spring are simulated using spring elements, and the support stiffness of the support bearing and axial wave spring is calibrated by calibrating the stiffness of the spring elements.

[0114] See Figure 1 The support stiffness of the support bearing is divided into axial stiffness and radial stiffness. To simulate the support state of the support bearing during the operation of the permanent magnet synchronous motor, two types of springs, oblique and radial, are used to simulate the bearing balls.

[0115] Define the stiffness value of the oblique spring;

[0116] The radial stiffness K of the bearing can be obtained from the bearing's design parameters. r and axial stiffness K t The stiffness of both the radial and oblique spring units of the bearing is set to unit stiffness, i.e., 1 N / mm. Material properties are assigned to the inner and outer rings of the bearing. The outer ring nodes are constrained, and an axial unit force load of 1 N is applied to the inner ring. The axial displacement x1 of the inner ring is obtained through simulation calculation. The stiffness value of the simulated bearing oblique spring can then be derived using the following formula:

[0117] k t =K t ·x1

[0118] In the formula:

[0119] k t —Stiffness value of the inclined spring, in N / mm;

[0120] K t —Bearing radial stiffness, in N / mm;

[0121] x1 — Axial displacement of the bearing inner ring, in mm;

[0122] Define the stiffness value of the radial spring.

[0123] The calculated oblique spring stiffness is assigned to the corresponding spring element, and the radial spring stiffness value is solved. Similarly, the outer ring node of the bearing is constrained, and a radial unit force load of 1N is applied to the inner ring of the bearing. The radial displacement R1 of the inner ring is obtained through simulation calculation. Then, the radial spring element stiffness is set to twice the unit stiffness, i.e., 2N / mm, and the above loading process is repeated to obtain the radial displacement R2 of the inner ring of the bearing. The radial spring stiffness can then be calculated using the following formula:

[0124] k r =(K r R1R2-2R2+R1) / (R1-R2)

[0125] In the formula:

[0126] k r —The stiffness value of the radial spring, in N / mm;

[0127] K r —Bearing radial stiffness, in N / mm;

[0128] R1 — Radial displacement of the bearing inner ring under a load of 1N, in mm;

[0129] R2 — Radial displacement of the bearing inner ring under a 2N load, in mm;

[0130] See Figure 2a and Figure 2bThe axial fixation of the motor shaft often employs a constraint at one end and a preloaded wave spring at the other. During initial assembly, the wave spring has an initial compression. A spring unit is used to simulate the support stiffness of the axial wave spring. The axial stiffness K of the wave spring is given, and the initial axial preload after assembly is F0. The simulated axial preload position of the wave spring is shown in Figure 2. Springs evenly distributed circumferentially are used to simulate the stiffness of the axial wave spring. If n springs are evenly distributed circumferentially, the stiffness k of the spring unit can be obtained by the following formula:

[0131] k = K / n

[0132] In the formula:

[0133] k — simulates the stiffness of a spring, in N / mm;

[0134] K—Axial stiffness parameter of wave spring, unit N / mm;

[0135] n — the number of circumferential springs in the simulated waveform spring;

[0136] The axial wave spring has an initial compression, which is obtained by the following formula:

[0137] Δl=F0 / K

[0138] Δl — Initial compression of the spring, in mm;

[0139] F0—Initial preload of the axial preload device, in N.

[0140] Structural stiffness simulation of rotor core and stator. The structural stiffness of a single-material component is determined by its shape and material properties. However, for motor rotors and stators composed of multiple layers of thin silicon steel sheets, modeling each sheet would significantly increase the computational load. Therefore, this type of component is modeled as a whole, and its stiffness characteristics along different directions are simulated by defining the anisotropic properties of its material. The anisotropic parameters are shown in Table 1 below.

[0141] Table 1. Anisotropic material properties of stator core and rotor core

[0142]

[0143] Step 2: Determine the load parameters;

[0144] 21) Identify the main loads affecting air gap changes;

[0145] a. Centrifugal force load generated during high-speed rotor operation;

[0146] b. Unbalanced magnetic pull load caused by rotor eccentricity and uneven air gap;

[0147] c. Eccentric force load generated by the rotor's eccentricity;

[0148] d. The inertial force load generated by impact during the operation of the motor;

[0149] e. Thermal expansion force load generated by the increase in internal temperature of the motor;

[0150] 22) Apply the main loads that affect the air gap change;

[0151] a. Centrifugal force load;

[0152] When the rotor system operates at high speed, the rotor core tends to expand outward due to the centrifugal load. This centrifugal load is applied at the motor's maximum speed.

[0153] ω max =2πn max / 60

[0154] In the formula:

[0155] n max —Maximum motor speed, in r / min;

[0156] ω max —Maximum angular velocity of the motor, in rad / s;

[0157] b. Unbalanced magnetic tensile load;

[0158] When the motor rotor is running, the eccentricity causes an unbalanced magnetic pull. This unbalanced magnetic pull, in turn, increases the rotor eccentricity, resulting in an even greater unbalanced magnetic pull. The specific relationship is as follows:

[0159] σ=σ0+Δσ

[0160] Δσ=F(σ) / K0

[0161] F(σ)=σ·βπDlB 2 / (2αμ0)

[0162] In the formula:

[0163] σ — Total eccentricity, in mm.

[0164] σ0 — Static eccentricity, in mm;

[0165] Δσ — the eccentricity caused by unbalanced magnetic pull, in mm;

[0166] F(σ) — Unbalanced magnetic pull function, in N;

[0167] K0—Support stiffness of the rotor system, N / mm;

[0168] β—Empirical coefficient, taken as 0.5;

[0169] D – Stator inner diameter, in mm;

[0170] l—Core length, in mm;

[0171] B—Average magnetic flux density in the air gap, in tons (T);

[0172] μ0 — Permeability in vacuum, N / A 2 ;

[0173] The formulas for calculating the total eccentricity of the air gap and the unbalanced magnetic pull are obtained as follows:

[0174] σ=σ0·K0 / (K0-λ)

[0175] F(σ)=λσ0·K0 / (K0-λ)

[0176] In the formula, λ=βπDlB 2 / (2αμ0), where the parameters are obtained directly from the parameters of the permanent magnet motor;

[0177] c. Eccentric force load;

[0178] Due to manufacturing errors and assembly errors within the machine, the rotor exhibits static eccentricity. Since rotor eccentricity is unrelated to assembly eccentricity, and the additional eccentricity caused by the eccentric force generated during rotor operation is small in magnitude and cannot be directly obtained, it can be ignored. The static eccentric force load generated by rotor operation is calculated as follows:

[0179]

[0180] In the formula:

[0181] σ0 — Static eccentricity, in mm;

[0182] m—Total rotor mass, in kg;

[0183] The dynamic eccentric force load generated by the rotor operation is calculated as follows:

[0184]

[0185] In the formula:

[0186] m—Total rotor mass, in kg;

[0187] K0 can be obtained through simulation calculation. After the finite element model of the whole machine is built, the deformation is solved by applying radial force to the rotor, and the support stiffness is calculated by using the ratio of force to deformation.

[0188] d. Inertial force load;

[0189] When the motor is in an impact condition during operation, an acceleration load 'a' is applied to the rotor system. The magnitude of the load depends on the actual working conditions.

[0190] e. Thermal expansion force load;

[0191] Since the motor experiences temperature rise during operation and the temperature field distribution varies in different parts, different temperature values ​​are assigned to each part based on the motor temperature field test measurement or simulation calculation results.

[0192] Step 3: After establishing the analysis model, perform the calculation in the finite element analysis software to obtain the deformation difference between the outer ring of the rotor core and the inner ring of the stator core, which is the change value of the air gap. By summing it with the total eccentricity σ, the result is compared with the design air gap value to assess the risk of rotor-stator collision.

[0193] Furthermore, the specific method for mitigating the risk of collision and abrasion in step three is as follows:

[0194] If the following formula holds true, there is a risk of collision / grinding:

[0195] (U+σ)·S≥T

[0196] In the formula:

[0197] U—The calculated deformation difference between the outer ring of the rotor core and the inner ring of the stator core, in mm;

[0198] S – Safety factor, greater than 1;

[0199] T – Air gap value, in mm.

[0200] Example 2

[0201] Figure 4 This is a schematic diagram of a device for predicting air gap changes in a permanent magnet synchronous motor, provided in Embodiment 2 of the present invention. This embodiment is applicable to the prediction of air gap changes in permanent magnet synchronous motors. The device can be implemented using software and / or hardware, and can be integrated into any device that provides the function of predicting air gap changes in permanent magnet synchronous motors, such as… Figure 4 As shown, the device for predicting changes in the air gap of a permanent magnet synchronous motor specifically includes:

[0202] A model building module is used to build a finite element assembly model of the entire permanent magnet synchronous motor.

[0203] The determination module is used to determine the calculated load parameters;

[0204] The judgment module is used to solve the analysis model in the finite element analysis software after the analysis model is established. The deformation difference between the outer ring of the rotor core and the inner ring of the stator core is the change value of the air gap. By summing it with the total eccentricity σ, the result is compared with the design air gap value to assess the risk of collision and rubbing between the rotor and the stator.

[0205] The above-described products can perform the methods provided in any embodiment of the present invention, and have the corresponding functional modules and beneficial effects for performing the methods.

[0206] Example 3

[0207] Figure 5 This is a schematic diagram of the structure of a computer device according to Embodiment 4 of the present invention. Figure 5 A block diagram of an exemplary computer device 12 suitable for implementing embodiments of the present invention is shown. Figure 5 The computer device 12 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of the present invention.

[0208] like Figure 5 As shown, the computer device 12 is represented in the form of a general-purpose computing device. The components of the computer device 12 may include, but are not limited to: one or more processors or processing units 16, system memory 28, and a bus 18 connecting different system components (including system memory 28 and processing unit 16).

[0209] Bus 18 represents one or more of several bus architectures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any of the various bus architectures. For example, these architectures include, but are not limited to, the Industry Standard Architecture (ISA) bus, the Micro Channel Architecture (MAC) bus, the Enhanced ISA bus, the Video Electronics Standards Association (VESA) local bus, and the Peripheral Component Interconnect (PCI) bus.

[0210] Computer device 12 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by computer device 12, including volatile and non-volatile media, removable and non-removable media.

[0211] System memory 28 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 30 and / or cache memory 32. Computer device 12 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 34 may be used to read and write non-removable, non-volatile magnetic media (…). Figure 5 Not shown; usually referred to as a "hard drive"). Although Figure 5Not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk") and an optical disk drive for reading and writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) may be provided. In these cases, each drive may be connected to bus 18 via one or more data media interfaces. Memory 28 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of the present invention.

[0212] A program / utility 40 having a set (at least one) of program modules 42 may be stored, for example, in memory 28. Such program modules 42 include—but are not limited to—an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment. Program modules 42 typically perform the functions and / or methods described in the embodiments of the present invention.

[0213] The computer device 12 can also communicate with one or more external devices 14 (e.g., keyboard, pointing device, display 24, etc.), and with one or more devices that enable a user to interact with the computer device 12, and / or with any device that enables the computer device 12 to communicate with one or more other computing devices (e.g., network card, modem, etc.). This communication can be performed via the input / output (I / O) interface 22. Furthermore, in this embodiment, the display 24 of the computer device 12 is not an independent entity, but is embedded in a mirror, so that when the display surface of the display 24 is not displayed, the display surface of the display 24 and the mirror surface visually blend together. Moreover, the computer device 12 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via the network adapter 20. As shown, the network adapter 20 communicates with other modules of the computer device 12 via the bus 18. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with computer device 12, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0214] The processing unit 16 executes various functional applications and data processing by running programs stored in the system memory 28, such as implementing a prediction method for air gap changes of a permanent magnet synchronous motor provided in the embodiments of the present invention.

[0215] Example 4

[0216] Embodiment 4 of the present invention provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements a method for predicting air gap changes in a permanent magnet synchronous motor as provided in all embodiments of the present application.

[0217] Any combination of one or more computer-readable media may be used. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device.

[0218] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including—but not limited to—electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of transmitting, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0219] The program code contained on a computer-readable medium may be transmitted using any suitable medium, including—but not limited to—wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0220] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0221] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for predicting air gap changes in a permanent magnet synchronous motor, characterized in that, Includes the following steps: Step 1: Establish the finite element assembly model of the permanent magnet synchronous motor; Step 2: Determine the load parameters, as detailed below: 21) Identify the main loads affecting air gap changes; a. Centrifugal force load generated during high-speed rotor operation; b. Unbalanced magnetic pull load caused by rotor eccentricity and uneven air gap; c. Eccentric force load generated by the rotor's eccentricity; d. The inertial force load generated by impact during the operation of the motor; e. Thermal expansion force load generated by the increase in internal temperature of the motor; 22) Apply the main loads that affect the air gap change; a. Centrifugal force load; When the rotor system operates at high speed, the rotor core tends to expand outward due to the centrifugal load. This centrifugal load is applied at the motor's maximum speed. In the formula: —Maximum motor speed, in units ; —Maximum angular velocity of the motor, in units ; b. Unbalanced magnetic tensile load; When the motor rotor is running, the eccentricity causes an unbalanced magnetic pull. This unbalanced magnetic pull, in turn, increases the rotor eccentricity, resulting in an even greater unbalanced magnetic pull. The specific relationship is as follows: In the formula: —Total eccentricity, in units ; —Static eccentricity, unit ; —The eccentricity caused by the unbalanced magnetic pull, in units ; —Unbalanced magnetic pull function, unit ; —The support stiffness of the rotor system, ; —Empirical coefficient, taken as 0.5; —Stator inner diameter, unit ; — Core length, unit ; —Average magnetic flux density in the air gap, in units ; —Permeability in vacuum ; The formulas for calculating the total air gap eccentricity and unbalanced magnetic pull are obtained as follows: In the formula The parameters are obtained directly from the parameters of the permanent magnet motor; c. Eccentric force load; The static eccentric force load generated by the rotor operation is calculated as follows: In the formula: —Static eccentricity, unit ; —Total rotor mass, in units ; The dynamic eccentric force load generated by the rotor operation is calculated as follows: In the formula: —Total rotor mass, in units ; d. Inertial force load; When the motor is in operation, it experiences impact conditions, which apply acceleration loads to the rotor system. The load value depends on the actual working conditions; e. Thermal expansion force load; Since the motor experiences temperature rise during operation and the temperature field distribution varies in different parts, different temperature values ​​are assigned to each part based on the motor temperature field test measurement or simulation calculation results. Step 3: After establishing the analysis model, perform the calculation in the finite element analysis software to obtain the deformation difference between the outer ring of the rotor core and the inner ring of the stator core, which is the change in air gap. This change is then compared with the total eccentricity. Summing the results and comparing them with the design air gap value, the risk of rotor-stator rubbing is assessed; the specific method for assessing the rubbing risk is as follows: If the following formula holds true, there is a risk of collision / grinding: In the formula: —The calculated deformation difference between the outer ring of the rotor core and the inner ring of the stator core, in units of ; —Safety factor, greater than 1; —Air gap value, unit .

2. The method for predicting air gap changes in a permanent magnet synchronous motor according to claim 1, characterized in that, The specific method of step one is as follows: The finite element assembly model includes modeling the motor shaft, rotor core, permanent magnet, support bearing, axial wave spring, motor housing, and stator.

3. The method for predicting air gap changes in a permanent magnet synchronous motor according to claim 2, characterized in that, The motor shaft, rotor core, permanent magnet, motor housing, and stator are modeled using solid elements; the support bearing and axial wave spring are simulated using spring elements, and the support stiffness of the support bearing and axial wave spring is calibrated by calibrating the stiffness of the spring elements.

4. The method for predicting air gap changes in a permanent magnet synchronous motor according to claim 3, characterized in that, The support stiffness of the bearing is divided into axial stiffness and radial stiffness. To simulate the support state of the bearing during operation of the permanent magnet synchronous motor, two types of springs, oblique and radial, are used to simulate the bearing balls. The stiffness value of the oblique spring is calculated using the following formula: In the formula: —Stiffness value of the oblique spring, in units ; —Bearing radial stiffness, unit ; —Axial displacement of the bearing inner ring, in units ; The stiffness value of the radial spring is obtained by the following formula: In the formula: —The stiffness value of the radial spring, in units ; —Bearing radial stiffness, unit ; —Radial displacement of the bearing inner ring under a load of 1N, in units ; —Radial displacement of the bearing inner ring under a 2N load, in units ; The stiffness of the axial wave spring is obtained by the following formula: In the formula: —Simulating the stiffness of a spring, in units ; —Axial stiffness parameter of wave spring, unit ; —The number of circumferential springs in the simulated waveform spring; The axial wave spring has an initial compression, which is obtained by the following formula: —Initial compression of the spring, in units ; —Initial preload of the axial preload device, unit .

5. The method for predicting air gap changes in a permanent magnet synchronous motor according to claim 2, characterized in that, The rotor core and stator simulate stiffness characteristics along different directions by defining the anisotropic properties of the materials.

6. A stiffness simulation device for modal analysis of a permanent magnet synchronous motor, characterized in that, The device includes: A model building module is used to build a finite element assembly model of the entire permanent magnet synchronous motor. The determination module is used to determine the calculated load parameters; specifically as follows: 22) Identify the main loads affecting air gap changes; a. Centrifugal force load generated during high-speed rotor operation; b. Unbalanced magnetic pull load caused by rotor eccentricity and uneven air gap; c. Eccentric force load generated by the rotor's eccentricity; d. The inertial force load generated by impact during the operation of the motor; e. Thermal expansion force load generated by the increase in internal temperature of the motor; 22) Apply the main loads that affect the air gap change; a. Centrifugal force load; When the rotor system operates at high speed, the rotor core tends to expand outward due to the centrifugal load. This centrifugal load is applied at the motor's maximum speed. In the formula: —Maximum motor speed, in units ; —Maximum angular velocity of the motor, in units ; b. Unbalanced magnetic tensile load; When the motor rotor is running, the eccentricity causes an unbalanced magnetic pull. This unbalanced magnetic pull, in turn, increases the rotor eccentricity, resulting in an even greater unbalanced magnetic pull. The specific relationship is as follows: In the formula: —Total eccentricity, in units ; —Static eccentricity, unit ; —The eccentricity caused by the unbalanced magnetic pull, in units ; —Unbalanced magnetic pull function, unit ; —The support stiffness of the rotor system, ; —Empirical coefficient, taken as 0.5; —Stator inner diameter, unit ; — Core length, unit ; —Average magnetic flux density in the air gap, in units ; —Permeability in vacuum ; The formulas for calculating the total air gap eccentricity and unbalanced magnetic pull are obtained as follows: In the formula The parameters are obtained directly from the parameters of the permanent magnet motor; c. Eccentric force load; The static eccentric force load generated by the rotor operation is calculated as follows: In the formula: —Static eccentricity, unit ; —Total rotor mass, in units ; The dynamic eccentric force load generated by the rotor operation is calculated as follows: In the formula: —Total rotor mass, in units ; d. Inertial force load; When the motor is in operation, it experiences impact conditions, which apply acceleration loads to the rotor system. The load value depends on the actual working conditions; e. Thermal expansion force load; Since the motor experiences temperature rise during operation and the temperature field distribution varies in different parts, different temperature values ​​are assigned to each part based on the motor temperature field test measurement or simulation calculation results. The judgment module is used to perform calculations in finite element analysis software after the analysis model is established. The deformation difference between the outer ring of the rotor core and the inner ring of the stator core is the change in air gap. This change is then compared with the total eccentricity. Summing the results and comparing them with the design air gap value, the risk of rotor-stator rubbing is assessed; the specific method for assessing the rubbing risk is as follows: If the following formula holds true, there is a risk of collision / grinding: In the formula: —The calculated deformation difference between the outer ring of the rotor core and the inner ring of the stator core, in units of ; —Safety factor, greater than 1; —Air gap value, unit .

7. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements a method for predicting air gap changes in a permanent magnet synchronous motor as described in any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements a method for predicting air gap changes in a permanent magnet synchronous motor as described in any one of claims 1-5.

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