External rotor permanent magnet synchronous motor key electromagnetic force harmonic extraction method and system

Abstract

The invention discloses a harmonic extraction method and system for key electromagnetic force waves of an outer rotor permanent magnet synchronous motor. The method comprises the following steps: calculating the electromagnetic force density of the inner surface of a permanent magnet of the outer rotor permanent magnet synchronous motor; according to the obtained electromagnetic force density data, two-dimensional Fourier decomposition is carried out on radial and tangential electromagnetic forces; obtaining modal shape data of the inner surface of the permanent magnet; performing one-dimensional Fourier decomposition on radial and tangential modal shapes at each axial position according to the obtained shape data of each order of modal; obtaining modal shape values of all orders at the response point; the selected radial electromagnetic force harmonic waves are reserved; calculating modal generalized forces corresponding to radial and tangential components of each order of modal; and calculating a complex field vibration acceleration generated by the electromagnetic force harmonic waves, wherein the electromagnetic force harmonic waves with relatively large vibration acceleration amplitude are key harmonic waves. The electromagnetic force harmonic waves extracted through the method serve as an optimization target, electromagnetic scheme design of the outer rotor motor is guided, and vibration noise of the outer rotor permanent magnet synchronous motor is restrained.

Description

Technical Field

[0001] The invention relates to a method and a system for extracting key electromagnetic force harmonics of an outer rotor permanent magnet synchronous motor, belonging to the technical field of multi-harmonic optimization of outer rotor permanent magnet synchronous motors. Background Art

[0002] At present, outer rotor permanent magnet synchronous motors are widely used in many industrial applications such as two-wheel electric hub motors, rotor vertical take-off and landing aircraft, and robot joint modules due to their many advantages such as direct load drive, high torque density, and compact structure. However, outer rotor motors are usually accompanied by high-frequency howling during operation, which directly affects the user experience. Low electromagnetic vibration and noise performance design has become one of the core performance indicators of outer rotor permanent magnet synchronous motors.

[0003] The electromagnetic force waves of the prior art are mainly based on the inner rotor structure permanent magnet synchronous motor. A two-dimensional or three-dimensional Fourier decomposition analysis method or a modal vibration type analysis method is used to analyze the time / space harmonic characteristics of the radial electromagnetic force waves of the inner rotor permanent magnet synchronous motor, and then the main harmonic components of the electromagnetic force waves are determined according to the harmonic characteristics, and the motor structure is optimized to reduce electromagnetic noise. For example, in the publication number CN 115996006, an electromagnetic force wave analysis method based on three-dimensional Fourier decomposition is proposed to determine the time, space axial and space tangential three-dimensional harmonic characteristics of the electromagnetic force of the motor; in the publication number CN 115994445, a modal characteristic analysis method is proposed, which converts the modal displacement from the space domain to the "wave number domain" through the Fourier decomposition of the two-dimensional modal vibration type data of the radial and axial multiple degrees of freedom of each modal vibration type space, and uses the amplitude and wave number to analyze the vibration noise of the inner rotor permanent magnet synchronous motor excited by the electromagnetic force. Publication No. CN113468786 proposes a stator concentrated force method, which calculates the concentrated force of each tooth surface by stator tooth surface area integral budget. Publication No. CN117875128 proposes a method for obtaining the electromagnetic force of the stator grid node of a permanent magnet synchronous motor, which obtains the time domain electromagnetic force of the stator grid node at each speed point by reading the stator grid file.

[0004] However, for the permanent magnet synchronous motor with outer rotor structure, the current mainstream solution is the surface-mounted permanent magnet rotor topology. Since the magnetic permeability of the permanent magnet is similar to the motor air gap, the tangential electromagnetic force amplitude is large, and it can also generate large radial electromagnetic vibrations; in addition, the vibration amplitudes and phases generated by different electromagnetic force waves are not the same, and the vibration acceleration of the same frequency can be excited by multiple electromagnetic force waves at the same time. The existing electromagnetic force wave decomposition method is mainly based on radial electromagnetic force waves, and it is impossible to extract the relationship between the vibration accelerations generated by each order of electromagnetic force. Therefore, it is necessary to combine the generation mechanism of the vibration acceleration of the outer rotor permanent magnet synchronous motor and propose a new method for extracting the key electromagnetic force harmonics of the outer rotor permanent magnet synchronous motor, so as to provide the electromagnetic force harmonic optimization target for the vibration and noise suppression of the outer rotor permanent magnet synchronous motor. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for extracting key electromagnetic force harmonics of an outer rotor permanent magnet synchronous motor, provide electromagnetic force harmonic optimization targets for the low vibration and noise design of the outer rotor structure permanent magnet synchronous motor, so as to further suppress the vibration and noise of the outer rotor permanent magnet synchronous motor.

[0006] In order to solve the above technical problems, the present invention provides a method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor, comprising the following steps:

[0007] Step S1, calculating the electromagnetic force density on the inner surface of the permanent magnet of the outer rotor permanent magnet synchronous motor, wherein the electromagnetic force density data at least includes electromagnetic force density data of radial, circumferential and axial degrees of freedom of the inner surface of multiple permanent magnets;

[0008] Step S2, based on the acquired electromagnetic force density data, perform two-dimensional Fourier decomposition on the radial and tangential electromagnetic forces respectively to obtain the spatial order ε corresponding to the radial electromagnetic force density rp, , time order ξ rp , amplitude F εrpξrp and phase φ εrpξrp ;and

[0009] The spatial order ε corresponding to the tangential electromagnetic force density tp , time order ξ tp , amplitude F εtpξtp and phase φ εtpξtp ;

[0010] Step S3, calculating each order of modal vibration shape and frequency of the permanent magnet synchronous motor rotor, and obtaining modal vibration shape data of the inner surface of the permanent magnet, wherein each order of modal vibration shape data at least includes modal vibration shape values ​​of the radial, circumferential and axial degrees of freedom of the inner surface of the permanent magnet;

[0011] Step S4, based on the acquired vibration mode data of each order mode, perform one-dimensional Fourier decomposition on the radial and tangential vibration modes at each axial position, and obtain the radial vibration mode σ at each axial position z. r The amplitude of the subharmonic Φ hzσr and phase φ hzσr , and the tangential mode shape σ t The amplitude of the subharmonic Φ hzσt and phase φ hzσt ;

[0012] Step S5, obtaining the values ​​of each order of mode shapes at the response point according to the coordinate value of the response position in the acquired h-th order mode shape data;

[0013] Step S6, according to the spatial order ε of the radial electromagnetic force density obtained in step 2 rp and the spatial order σ of the radial component of the modal vibration shape obtained in step 4 r , only the spatial order ε of the radial electromagnetic force density is retained rp and the spatial order σ of the radial component of the modal vibration shape r Equal radial electromagnetic force harmonics;

[0014] Similarly, according to the spatial order ε of the tangential electromagnetic force density obtained in step 2 tp and the spatial order σ of the tangential component of the modal vibration shape obtained in step 4 t , only the spatial order ε of the tangential electromagnetic force density is retained tp and the spatial order of the tangential component of the modal vibration shape σ t Equal radial electromagnetic force harmonics;

[0015] Step S7, according to the radial electromagnetic force density harmonic amplitude F in step 2 εrpξrp and phase φ εrpξrp , the harmonic amplitude of the radial mode shape at each axial position Φ hzσr and phase φ hzσr , calculate the modal generalized force F corresponding to the radial component of each mode hrεrpξrp ;

[0016] According to the harmonic amplitude F of the tangential electromagnetic force density in step 2 εtpξtp and phase φ εtpξtp , the harmonic amplitude of the tangential mode shape at each axial position Φ hzσt and phase φ hzσt , calculate the modal generalized force F corresponding to the tangential component of each mode htεtpξtp ;

[0017] Step S8: according to the modal generalized force F corresponding to the radial electromagnetic force of each order mode hrεrpξrp , the modal vibration value φ at the response point rh , angular frequency ω of electromagnetic force, h-order modal frequency ω h and damping ζ h , calculate the response point by (ε rp ,ξ rp )-order radial electromagnetic force harmonics generated by the complex domain vibration acceleration; similarly, calculate the (ε tp ,ξ tp ) order tangential electromagnetic force harmonic vibration acceleration;

[0018] Step S9, extracting key harmonics according to the vibration acceleration amplitudes generated by electromagnetic force harmonics of various orders, and the electromagnetic force harmonics with larger vibration acceleration amplitudes are the key harmonics.

[0019] In the aforementioned method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor, in step 1, electromagnetic finite element software is used to calculate the electromagnetic force density on the inner surface of the permanent magnet of the outer rotor permanent magnet synchronous motor.

[0020] In the aforementioned method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor, in step 3, structural finite element software is used to calculate the modal vibration shapes and frequencies of each order of the motor rotor.

[0021] In the above-mentioned method for extracting key electromagnetic force waves harmonics of an outer rotor permanent magnet synchronous motor, in step S7, the modal generalized force F corresponding to the radial component of each order mode is calculated according to the following formula: hrεrpξrp ;

[0022]

[0023] Among them, R PM is the radius of the inner surface of the permanent magnet, L is the stack length of the motor, ω is the angular frequency of the electromagnetic force, ω r is the mechanical angular frequency, t is the time, and z is the axial position coordinate.

[0024] The above-mentioned method for extracting key electromagnetic force waves harmonics of an outer rotor permanent magnet synchronous motor is as follows: In step S7, the modal generalized force F corresponding to the tangential component of each order mode is calculated according to the following formula: htεtpξtp ;

[0025] .

[0026] In the above-mentioned method for extracting key electromagnetic force waves harmonics of an outer rotor permanent magnet synchronous motor, in step S8, the following formula is used to calculate the harmonics of the response point (ε rp ,ξ rp )-order radial electromagnetic force harmonics generate complex domain vibration acceleration,

[0027]

[0028] Among them, N is the highest modal order of the motor, i is the imaginary unit, and the complex domain vibration acceleration is projected onto the real coordinate axis, which is the actual vibration acceleration amplitude.

[0029]

[0030] Among them, Real is the real part function.

[0031] In the above-mentioned method for extracting key electromagnetic force waves harmonics of an outer rotor permanent magnet synchronous motor, in step S8, the following formula is used to calculate (ε tp ,ξ tp ) order tangential electromagnetic force harmonic vibration acceleration;

[0032]

[0033] .

[0034] A computer device / equipment / system comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above method.

[0035] A computer-readable storage medium stores a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0036] A computer program product comprises a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0037] Beneficial effects achieved by the invention: The method of the invention further quantitatively evaluates the acceleration amplitude of radial and tangential electromagnetic force density on radial electromagnetic vibration by calculating the radial vibration acceleration generated by each harmonic in the radial / tangential electromagnetic force of the outer rotor permanent magnet synchronous motor, and can analyze the phase relationship between the radial electromagnetic vibration acceleration generated by each electromagnetic force wave, thereby extracting the key harmonics in the radial and tangential electromagnetic force harmonics. The key harmonics extracted by the present invention can provide electromagnetic force harmonic optimization targets for outer rotor structure permanent magnet synchronous motors in industrial fields such as robot joint modules, hub motors and rotors, so as to suppress the electromagnetic vibration and noise of outer rotor permanent magnet synchronous motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the electromagnetic topology structure of the outer rotor permanent magnet synchronous motor used in the embodiment of the present invention;

[0039] Figure 2 This is a spatial distribution diagram of electromagnetic force corresponding to 24 times the frequency in an embodiment of the present invention;

[0040] Figure 3is a two-dimensional spectrum diagram of space and time corresponding to the radial and tangential electromagnetic force density on the inner surface of the permanent magnet in an embodiment of the present invention;

[0041] Figure 4 Schematic diagram of radial and tangential components of the inner surface of the outer rotor permanent magnet of the second-order modal vibration type in an embodiment of the present invention;

[0042] Figure 5 It is the radial and tangential modal vibration mode distribution and one-dimensional spectrum diagram of the inner surface of the permanent magnet in the circumferential direction at a certain axial position in an embodiment of the present invention;

[0043] Figure 6 Schematic diagram of radial acceleration amplitudes generated by various order spatial harmonics of 24 times rotational frequency electromagnetic force calculated in an embodiment of the present invention;

[0044] Figure 7 Schematic diagram of radial acceleration amplitudes generated by spatial harmonics of 48-fold rotational frequency electromagnetic force calculated in an embodiment of the present invention;

[0045] Figure 8 It is a flow chart of a method for extracting key electromagnetic force wave harmonics of an outer rotor permanent magnet synchronous motor in an embodiment of the present invention.

[0046] Reference numerals: 1. stator, 2. rotor, 3. permanent magnet, 4. coil, 5. inner surface of permanent magnet, 6. end cover, 7. rotor back iron, 8. acceleration sensor. DETAILED DESCRIPTION

[0047] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0048] Example 1

[0049] This embodiment provides a method for extracting key electromagnetic force wave harmonics of an outer rotor permanent magnet synchronous motor. The outer rotor permanent magnet synchronous motor has 24 slots and 22 poles. The topology of the two-dimensional cross section and the three-dimensional rotor structure topology are as follows: Figure 1 As shown, the method proposed in this embodiment is used to extract the key harmonics of the electromagnetic force, so as to optimize the electromagnetic vibration and noise of the outer rotor permanent magnet synchronous motor, which includes the following steps:

[0050] Step S1, using electromagnetic finite element software to calculate the electromagnetic force density on the inner surface of the surface-mounted permanent magnet of the outer rotor permanent magnet synchronous motor, and then uniformly sampling the electromagnetic force density data on the inner surface of the permanent magnet;

[0051] The electromagnetic finite element software may be commercial software ANSYS Maxwell, JMAG Designer, Hyperworks Flux or open source software FEMM, etc.;

[0052] The electromagnetic force density data at least includes: electromagnetic force density data of three degrees of freedom, namely radial, circumferential and axial directions, on the inner surfaces of multiple permanent magnets;

[0053] Step S2, based on the acquired electromagnetic force density data, perform two-dimensional Fourier decomposition on the radial electromagnetic force to obtain the spatial order ε corresponding to the radial electromagnetic force density rp, , time order ξ rp , amplitude F εrpξrp and phase φ εrpξrp ;

[0054] Similarly, by performing two-dimensional Fourier decomposition on the tangential electromagnetic force density, the spatial order ε corresponding to the tangential electromagnetic force density is obtained: tp , time order ξ tp , amplitude F εtpξtp and phase φ εtpξtp ; The results are as follows Figure 3 As shown;

[0055] Figure 2 This is the electromagnetic force spatial distribution diagram corresponding to 24 times the frequency in this embodiment, Figure 2 In the figure, (a) is the spatial distribution vector diagram of the total electromagnetic force cross section, Figure 2 (b) is the spatial distribution vector diagram of the radial electromagnetic force component. Figure 2 (c) is the spatial distribution vector diagram of the tangential electromagnetic force component. Through Fourier decomposition, the radial / tangential electromagnetic force component can be further decomposed into harmonics, and the electromagnetic vibration generated by each harmonic can be calculated;

[0056] Step S3, using structural finite element software to calculate the modal vibration mode and frequency of each order of the motor rotor, and obtain the modal vibration mode data of the inner surface of the surface-mounted permanent magnet, each order of modal vibration mode data at least includes: the modal vibration mode values ​​of the radial, circumferential and axial degrees of freedom of the inner surface of multiple permanent magnets; wherein the radial and tangential component results of the second-order mode are as follows: Figure 4 As shown, Figure 4 In the figure, (a) is the radial component and (b) is the tangential component;

[0057] Structural finite element software can be Ansys Mechanical, JMAG Designer or Hyper works, etc.

[0058] Step S4: Based on the acquired vibration mode data of each order mode, one-dimensional Fourier decomposition is performed on the radial mode vibration mode at each axial position to obtain the radial mode vibration mode σ at each axial position z.r The amplitude of the subharmonic Φ hzσr and phase φ hzσr Similarly, the tangential component of the modal vibration shape is decomposed into one-dimensional Fourier to obtain the tangential modal vibration shape σ t The amplitude of the subharmonic Φ hzσt and phase φ hzσt , the results are as follows Figure 5 As shown in (b) and (c);

[0059] Figure 5 In the figure, (a) is the spatial distribution diagram of the 2nd, 3rd, and 4th order modes, (b) is the amplitude spectrum diagram corresponding to the 2nd, 3rd, and 4th order modes, and (c) is the phase spectrum diagram corresponding to the 2nd, 3rd, and 4th order modes. It can be seen that in addition to the ideal 2nd, 3rd, and 4th order spatial harmonics, there are multiple high-order spatial harmonics. The high-order spatial harmonics will also interact with the high-order electromagnetic force harmonics to produce a large electromagnetic vibration acceleration.

[0060] Step S5, acquiring modal vibration mode values ​​of each order at the response point according to the position coordinate value of the response position in the acquired h-th modal vibration mode data, wherein the modal vibration mode values ​​of each order at least include modal vibration mode values ​​of each order mode in the radial direction at the position of the response point;

[0061] Step S6, according to the spatial order ε of the radial electromagnetic force density obtained in step 2 rp and the spatial order σ of the radial component of the modal vibration shape obtained in step 4 r , only the spatial order ε of the radial electromagnetic force density is retained rp and the spatial order σ of the radial component of the modal vibration shape r Equal radial electromagnetic force harmonics;

[0062] Similarly, according to the spatial order ε of the tangential electromagnetic force density obtained in step 2 tp and the spatial order σ of the tangential component of the modal vibration shape obtained in step 4 t , only the spatial order ε of the tangential electromagnetic force density is retained tp and the spatial order of the tangential component of the modal vibration shape σ t Equal radial electromagnetic force harmonics;

[0063] Step S7, according to the radial electromagnetic force density harmonic amplitude F in step 2 εrpξrp and phase φ εrpξrp , the harmonic amplitude of the radial mode shape at each axial position Φ hzσr and phase φ hzσr , calculate the modal generalized force F corresponding to the radial component of each mode according to the following formula: hrεrpξrp ;

[0064]

[0065] Among them, R PM is the radius of the inner surface of the permanent magnet, L is the stack length of the motor, ω is the angular frequency of the electromagnetic force, ω r is the mechanical angular frequency, t is the time, and z is the axial position coordinate;

[0066] Similarly, according to the harmonic amplitude F of the tangential electromagnetic force density in step 2 εtpξtp and phase φ εtpξtp , the harmonic amplitude of the tangential mode shape at each axial position Φ hzσt and phase φ hzσt , calculate the modal generalized force F corresponding to the tangential component of each mode according to the following formula: htεtpξtp ;

[0067] .

[0068] Step S8: according to the modal generalized force F corresponding to the radial electromagnetic force of each order mode hrεrpξrp , the modal vibration value φ at the response point r h , angular frequency ω of electromagnetic force, h-order modal frequency ω h and damping ζ h , calculate the response point by (ε rp ,ξ rp )-order radial electromagnetic force harmonics generate complex domain vibration acceleration,

[0069]

[0070] Among them, N is the highest modal order of the motor, i is the imaginary unit, and the complex domain vibration acceleration is projected onto the real coordinate axis, which is the actual vibration acceleration amplitude.

[0071]

[0072] Among them, Real is the real part function;

[0073] Similarly, the calculation is given by (ε tp ,ξ tp )-order tangential electromagnetic force harmonic vibration acceleration

[0074]

[0075] ;

[0076] Step S9, extracting key harmonics according to the vibration acceleration amplitudes generated by electromagnetic force harmonics of various orders, and the electromagnetic force harmonics with larger vibration acceleration amplitudes are the key harmonics.

[0077] according to Figure 7, it can be seen that for the 24-fold frequency vibration, the electromagnetic vibrations generated by the radial and tangential electromagnetic forces are in opposite phases, and the 2nd, 20th, 24th, and 46th spatial harmonics are the key harmonics; for the 48-fold frequency vibration, the 4th, 26th, 48th, and 70th spatial harmonics are the key harmonics. The radial electromagnetic vibrations generated by the 24-fold frequency spatial harmonics are Figure 6 It can be seen that the 2nd, 20th, 24th, and 46th order electromagnetic forces are the key electromagnetic force harmonics in the 24-fold rotation frequency electromagnetic force; the radial electromagnetic vibrations generated by the 48-fold frequency spatial harmonics are Figure 7 It can be seen that the 4th, 26th, 48th, and 70th order electromagnetic forces are the key electromagnetic force harmonics in the 48-fold rotation frequency electromagnetic force. Figure 6 and Figure 7 It can be seen that each order of electromagnetic force contains both radial and tangential components, and the electromagnetic vibration accelerations they generate are in opposite phases and cancel each other out. Therefore, the multiple key electromagnetic force harmonics calculated by this method can be used as optimization targets to suppress the vibration noise of the outer rotor permanent magnet synchronous motor.

[0078] A computer device / equipment / system comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above method.

[0079] A computer-readable storage medium stores a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0080] A computer program product comprises a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0081] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0082] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0083] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor, characterized in that: The following steps are involved: Step S1, calculating the electromagnetic force density on the inner surface of the permanent magnet of the outer rotor permanent magnet synchronous motor, wherein the electromagnetic force density data at least includes electromagnetic force density data of radial, circumferential and axial degrees of freedom of the inner surface of multiple permanent magnets; Step S2, based on the acquired electromagnetic force density data, perform two-dimensional Fourier decomposition on the radial and tangential electromagnetic forces respectively to obtain the spatial order ε corresponding to the radial electromagnetic force density rp, , time order ξ rp , amplitude F εrpξrp and phase φ εrpξrp ;and The spatial order ε corresponding to the tangential electromagnetic force density tp , time order ξ tp , amplitude F εtpξtp and phase φ εtpξtp ; Step S3, calculating each order of modal vibration shape and frequency of the permanent magnet synchronous motor rotor, and obtaining modal vibration shape data of the inner surface of the permanent magnet, wherein each order of modal vibration shape data at least includes modal vibration shape values ​​of the radial, circumferential and axial degrees of freedom of the inner surface of the permanent magnet; Step S4, based on the acquired vibration mode data of each order mode, perform one-dimensional Fourier decomposition on the radial and tangential vibration modes at each axial position, and obtain the radial vibration mode σ at each axial position z. r The amplitude of the subharmonic Φ hzσr and phase φ hzσr , and the tangential mode shape σ t The amplitude of the subharmonic Φ hzσt and phase φ hzσt ; Step S5, obtaining the values ​​of each order of modal vibration shape at the response point according to the coordinate value of the response position in the acquired h-th order modal vibration shape data; Step S6, according to the spatial order ε of the radial electromagnetic force density obtained in step 2 rp and the spatial order σ of the radial component of the modal vibration shape obtained in step 4 r , only the spatial order ε of the radial electromagnetic force density is retained rp and the spatial order σ of the radial component of the modal vibration shape r Equal radial electromagnetic force harmonics; Similarly, according to the spatial order ε of the tangential electromagnetic force density obtained in step 2 tp and the spatial order σ of the tangential component of the modal vibration shape obtained in step 4 t , only the spatial order ε of the tangential electromagnetic force density is retained tp and the spatial order of the tangential component of the modal vibration shape σ t Equal radial electromagnetic force harmonics; Step S7, according to the radial electromagnetic force density harmonic amplitude F in step 2 εrpξrp and phase φ εrpξrp , the harmonic amplitude of the radial mode shape at each axial position Φ hzσr and phase φ hzσr , calculate the modal generalized force F corresponding to the radial component of each mode hrεrpξrp ; According to the harmonic amplitude F of the tangential electromagnetic force density in step 2 εtpξtp and phase φ εtpξtp , the harmonic amplitude of the tangential mode shape at each axial position Φ hzσt and phase φ hzσt , calculate the modal generalized force F corresponding to the tangential component of each mode htεtpξtp ; Step S8: according to the modal generalized force F corresponding to the radial electromagnetic force of each order mode hrεrpξrp , the modal vibration value φ at the response point r h , angular frequency ω of electromagnetic force, h-order modal frequency ω h and damping ζ h , calculate the response point by (ε rp ,ξ rp )-order radial electromagnetic force harmonics generated by the complex domain vibration acceleration; similarly, calculate the (ε tp ,ξ tp ) order tangential electromagnetic force harmonic vibration acceleration; Step S9, extracting key harmonics according to the vibration acceleration amplitudes generated by electromagnetic force harmonics of various orders, and the electromagnetic force harmonics with larger vibration acceleration amplitudes are the key harmonics.

2. The method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor according to claim 1, characterized in that: In step 1, electromagnetic finite element software is used to calculate the electromagnetic force density on the inner surface of the permanent magnet of the outer rotor permanent magnet synchronous motor.

3. The method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor according to claim 1, characterized in that: In step 3, structural finite element software is used to calculate the modal vibration shapes and frequencies of the motor rotor.

4. The method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor according to claim 1, characterized in that: In step S7, the modal generalized force F corresponding to the radial component of each mode is calculated according to the following formula: hrεrpξrp ; ； Among them, R PM is the radius of the inner surface of the permanent magnet, L is the stack length of the motor, ω is the angular frequency of the electromagnetic force, ω r is the mechanical angular frequency, t is the time, and z is the axial position coordinate.

5. The method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor according to claim 1, characterized in that: In step S7, the modal generalized force F corresponding to the tangential component of each mode is calculated according to the following formula: htεtpξtp ; 。 6. The method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor according to claim 1, characterized in that: In step S8, the following formula is used to calculate the response point (ε rp ,ξ rp )-order radial electromagnetic force harmonics generate complex domain vibration acceleration, ； Where N is the highest modal order of the motor, i is the imaginary unit, and the complex domain vibration acceleration is projected onto the real coordinate axis, which is the actual vibration acceleration amplitude. ； Among them, Real is the real part function.

7. The method for extracting key electromagnetic force waves and harmonics of an outer rotor permanent magnet synchronous motor according to claim 1, characterized in that: In step S8, the following formula is used to calculate (ε tp ,ξ tp ) order tangential electromagnetic force harmonic vibration acceleration; ； 。 8. A computer device / equipment / system comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method of claim 1.

9. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to claim 1 are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to claim 1 are implemented.

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