A method and system for detecting rotor eccentricity of a permanent magnet motor based on modal resonance

Abstract

The application provides a rotor eccentricity detection method and system based on modal resonance for a permanent magnet motor, and belongs to the field of permanent magnet motor eccentricity fault detection. The method comprises the following steps: obtaining the motor operating state and collecting the structural response signal; establishing a modal database to obtain the natural frequency and frequency band range of each order modal; constructing an air gap permeance modulation model to obtain an eccentricity candidate feature set through two-dimensional Fourier decomposition; performing frequency spectrum analysis on the structural response signal to obtain a power spectrum, and calculating a frequency band enhancement feature quantity in the modal frequency band; matching the eccentricity candidate feature set and the frequency band enhancement feature quantity, judging whether there is eccentricity through a preset eccentricity determination rule, and outputting the eccentricity type and eccentricity degree evaluation result. The application improves the observability and anti-interference ability of the eccentricity feature under complex working conditions, and realizes high-sensitivity, high-robustness and mechanism-explained detection and evaluation of the rotor eccentricity fault.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet motor eccentricity fault detection, and particularly relates to a method and system for detecting rotor eccentricity of permanent magnet motors based on modal resonance. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Permanent magnet motors, due to their high efficiency and high power density, are widely used in demanding applications such as electric vehicles, industrial drives, and aerospace propulsion. As motor design evolves towards higher speeds, wider speed ranges, and higher power densities, the coupling between the internal electromagnetic field and mechanical structure becomes increasingly complex. This leads to electromagnetic vibration and noise issues, which are gradually becoming key factors restricting motor reliability and comfort. Research shows that significant amplification of electromagnetic vibration and noise often stems from resonance effects. Specifically, when the spatial order of the electromagnetic force wave matches the modal order of the stator structure, and its excitation frequency is close to the structure's natural frequency, it triggers strong vibration and noise responses. Among these, low-order electromagnetic force waves, due to their longer wavelengths and more direct excitation of the structure, have a particularly significant impact on vibration.

[0004] In actual manufacturing, assembly, and long-term operation, rotor eccentricity is one of the common geometric deviations and fault modes in permanent magnet motors, mainly including three types: static eccentricity, dynamic eccentricity, and mixed eccentricity. Eccentricity leads to uneven air gap, triggering air gap magnetic permeability modulation effect, which in turn changes the distribution characteristics of air gap magnetic flux density and radial electromagnetic force waves. This change will further excite structural resonance, resulting in a significant increase in vibration and noise levels, especially near the mechanical rotation frequency and its harmonics, where the vibration response is often more prominent.

[0005] Currently, detection methods for rotor eccentricity faults can be mainly divided into two categories: electrical-side detection and mechanical-side detection. However, under complex actual operating conditions, motors often operate in environments with varying speeds, loads, and inverter power supplies. Factors such as current harmonics, switching frequency interference, and mechanical background noise can severely interfere with the stable extraction of eccentricity characteristics. Especially in the early stages of eccentricity or early fault stages, the characteristic signal amplitude is low and easily submerged by noise, leading to insufficient detection sensitivity and frequent false positives or false negatives. Furthermore, existing methods mostly focus on whether certain frequency components appear in the signal, failing to effectively correlate electromagnetic excitation characteristics with the resonant frequency band of the motor structure. Therefore, it is difficult to explain why eccentricity symptoms are more pronounced in certain speed ranges, and it is also difficult to reliably distinguish between the type and degree of eccentricity. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides a method and system for detecting rotor eccentricity of permanent magnet motors based on modal resonance. By utilizing the resonant amplification effect between eccentric excitation and structural modes, the observability and detection robustness of eccentricity features are improved, enabling effective identification and assessment of eccentricity type and degree.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions: The first aspect of this invention provides a method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance; A method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance, comprising: Acquire the motor's operating status and collect structural response signals during motor operation; Establish a modal database for the stator or stator-casing system to obtain the natural frequencies and frequency bands of each mode; A model for air gap magnetic permeability modulation caused by rotor eccentricity is constructed. By performing two-dimensional Fourier decomposition of the radial electromagnetic force wave in terms of spatial angle and time, a set of candidate features for eccentricity is obtained. The power spectrum is obtained by performing spectral analysis on the structural response signal, and the frequency band enhancement characteristic is calculated within the modal frequency band. The eccentricity candidate feature set is matched with the frequency band enhancement feature quantity, and the existence of eccentricity is determined by the preset eccentricity determination rule. The eccentricity type and eccentricity degree evaluation results are then output.

[0008] As a further technical solution, the motor operating state includes at least one of speed, load, or electromagnetic torque; The structural response signals during the operation of the motor include at least the vibration acceleration signal and noise sound pressure signal at the stator or housing.

[0009] As a further technical solution, an air gap magnetic permeability modulation model caused by rotor eccentricity is constructed. By performing two-dimensional Fourier decomposition of the radial electromagnetic force wave in terms of spatial angle and time, a set of candidate features for eccentricity is obtained, including: For different eccentric forms, corresponding mathematical models of air gap length and air gap magnetic permeability are established to clarify the temporal control mechanism of eccentricity on the air gap magnetic field. Based on the constructed model, the sideband characteristics introduced by rotor eccentricity in radial electromagnetic force waves are analyzed, including additional components in spatial order, modulation sidebands in time frequency and their correlation characteristics with mechanical frequency. By performing two-dimensional Fourier decomposition on the radial electromagnetic force wave along both spatial angle and time dimensions, the characteristic spectral peak distributions corresponding to different eccentric forms are extracted, forming a set of eccentric candidate features containing the characteristic patterns of each eccentric type and their corresponding spatial order-frequency coordinates.

[0010] As a further technical solution, spectral analysis is performed on the structural response signal to obtain the power spectrum, and the frequency band enhancement characteristic quantity is calculated within the modal frequency band, including: Spectral analysis of the acquired signal yields the amplitude spectrum or power spectrum; For each intrinsic frequency in the modal database, a modal band enhancement feature is constructed within its band window. The band enhancement feature includes band energy, band peak value, and normalized ratio relative to the healthy baseline.

[0011] As a further technical solution, the frequency band energy is:

[0012] in, For frequency band energy; Power spectrum; For each natural frequency in the modal database; The bandwidth of the mode.

[0013] The peak value of the frequency band is:

[0014] in, Peak value in the frequency band; The normalized ratio of the relative health baseline is:

[0015]

[0016] in, The normalized ratio of the frequency band energy relative to the healthy baseline; The normalized ratio of the frequency band peak value relative to the healthy baseline; , These are reference values ​​for a healthy state.

[0017] As a further technical solution, matching the eccentric candidate feature set with the frequency band enhancement feature quantity, and determining whether eccentricity exists through a preset eccentricity determination rule includes: The real-time extracted frequency band enhancement features are matched with the set of eccentricity candidate features, and the matching degree between each candidate feature and the current response is calculated. If the matching degree exceeds a set threshold, and the enhancement feature meets a preset amplitude or energy condition within the corresponding modal frequency band, then rotor eccentricity is determined to exist. Specifically: If a certain mode exists With a certain eccentric force wave characteristic , The spatial order of the radial electromagnetic force wave; satisfying And the corresponding modal frequency band enhancement index meets the threshold condition. or If so, it is determined that there is rotor eccentricity.

[0018] As a further technical solution, the criteria for determining the eccentricity type are as follows: If the frequency band enhancement feature is mainly manifested as spatial order sidebands and does not shift significantly with rotational speed, it is determined to be static eccentricity; If the frequency band enhancement feature exhibits a frequency shift sideband related to the mechanical frequency and affects multiple modal frequency bands, it is determined to be dynamic eccentricity; If it simultaneously possesses spatial order sideband and frequency shift sideband characteristics, it is determined to be a mixed eccentricity.

[0019] A second aspect of the present invention provides a permanent magnet motor rotor eccentricity detection system based on modal resonance.

[0020] A permanent magnet motor rotor eccentricity detection system based on modal resonance, comprising: The signal acquisition module is configured to: acquire the motor operating status and acquire the structural response signals during the motor operation process; The modal database construction module is configured to: establish a modal database for the stator or stator-casing system, and obtain the natural frequencies and frequency bands of each mode; The eccentricity candidate feature set acquisition module is configured to: construct an air gap magnetic permeability modulation model caused by rotor eccentricity, and obtain the eccentricity candidate feature set by performing two-dimensional Fourier decomposition of the radial electromagnetic force wave in terms of spatial angle and time. The feature extraction module is configured to: perform spectral analysis on the structural response signal to obtain the power spectrum, and calculate the frequency band enhancement feature quantity within the modal frequency band; The matching and determination module is configured to: match the eccentric candidate feature set with the frequency band enhancement feature quantity, determine whether eccentricity exists through preset eccentricity determination rules, and output the eccentricity type and eccentricity degree evaluation results.

[0021] A third aspect of the present invention provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the steps of the method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in the first aspect of the present invention.

[0022] The fourth aspect of the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in the method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in the first aspect of the present invention.

[0023] The above one or more technical solutions have the following beneficial effects: (1) This invention achieves an effective correlation between fault mechanism and detection characteristics through a complete physical link of “eccentricity → electromagnetic force wave sideband → modal matching → resonance peak enhancement”. This gives the detection results clear physical meaning, explaining why eccentricity symptoms are more prominent at certain speeds or frequency bands, avoiding the misjudgment and poor portability problems caused by relying on empirical frequency selection in traditional methods. By analyzing the order distribution of enhancement features within the modal frequency band, the sideband structure, and its correlation with mechanical frequency, this invention can effectively distinguish between different types of faults such as static eccentricity, dynamic eccentricity, and mixed eccentricity. At the same time, based on the calibration mapping relationship between frequency band enhancement index and eccentricity rate, quantitative or semi-quantitative assessment of the degree of eccentricity can be achieved, improving the engineering practical value of fault diagnosis.

[0024] (2) This invention does not rely on the direct visibility of eccentric features across the entire frequency band. Instead, it utilizes the resonant amplification effect between eccentric excitation and the inherent modes of the structure to significantly enhance the sideband excitation caused by minute eccentricity within the modal frequency band, thereby improving the signal-to-noise ratio of the feature signal. This method can still stably extract eccentric features under complex electrical noise, mechanical vibration, and variable operating condition interference, and is especially suitable for fault detection in the early stage of eccentricity or when the degree of eccentricity is small.

[0025] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0027] Figure 1 This is a flowchart of the method in the first embodiment.

[0028] Figure 2 This is a schematic diagram of the rotor eccentricity and geometric relationship in the first embodiment.

[0029] Figure 3 This is a finite element modal model diagram of the stator-casing in the first embodiment.

[0030] Figure 4 This is a flowchart of the modal testing measurement point layout and modal testing process in the first embodiment.

[0031] Figure 5 This is a comparison diagram of vibration acceleration and noise spectrum in the first embodiment.

[0032] Figure 6 This is a system structure diagram of the second embodiment. Detailed Implementation

[0033] It should be noted that the following detailed description is exemplary and aims to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0035] Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] The general idea proposed by the present invention: The present invention is based on the resonance effect between the electromagnetic force wave caused by eccentricity and the inherent mode of the motor structure. By constructing an eccentricity feature - structure mode matching mechanism, the modal band enhancement features related to eccentricity are extracted from vibration or noise signals. Utilizing the resonance amplification effect, the identifiability and signal - to - noise ratio of eccentricity features in complex background noise are significantly improved, realizing high - sensitivity detection of eccentricity faults. Further combined with feature mode analysis, static eccentricity, dynamic eccentricity and mixed eccentricity types can be distinguished, and based on the mapping relationship between the feature amplitude and the degree of eccentricity, quantitative or hierarchical evaluation of the degree of eccentricity can be achieved. The present invention takes into account the clarity of the mechanism, engineering practicability and detection robustness, providing a reliable means for the diagnosis of permanent - magnet motor eccentricity faults.

[0037] Embodiment 1 This embodiment discloses a method for detecting the eccentricity of a permanent - magnet motor rotor based on modal resonance. By constructing an eccentricity feature - structure mode matching mechanism, the modal band enhancement features related to eccentricity are extracted from vibration or noise signals. Utilizing the resonance amplification effect, the identifiability and signal - to - noise ratio of eccentricity features in complex background noise are significantly improved, realizing high - sensitivity detection of eccentricity faults.

[0038] Specifically, as Figure 1 shown, a method for detecting the eccentricity of a permanent - magnet motor rotor based on modal resonance includes: Step S1, obtain the operating state of the motor and collect the structural response signal during the operation of the motor.

[0039] The operating state of the motor includes at least one of speed, load, and electromagnetic torque. The acquisition methods of each operating state parameter are adapted to industrial actual detection scenarios. The real - time speed value and electromagnetic torque value can be directly collected through the speed sensor and torque sensor supporting the motor. The load parameter can be read from the operating parameters of the motor control system or obtained through torque and speed conversion; during the acquisition process, ensure that the sampling frequency of the operating state parameters matches the sampling frequency of the subsequent structural response signal, realizing the time - axis synchronization of the state parameters and the response signal, and avoiding deviation in subsequent frequency - domain and order analysis due to time difference.

[0040] The structural response signals during motor operation include at least the vibration acceleration signal and noise sound pressure signal at the stator or housing. A piezoelectric accelerometer is used to collect the vibration acceleration signal, and a sound level meter or microphone is used to collect the noise sound pressure signal. In addition, the rotational speed signal is simultaneously acquired to convert the frequency axis to an order axis or to achieve frequency normalization under variable speed conditions. The acquired signals undergo preprocessing such as detrending, bandpass filtering, and window function processing to improve the accuracy of subsequent spectral analysis.

[0041] Step S2: Establish a modal database for the stator or stator-casing system to obtain the natural frequencies and frequency bands of each mode.

[0042] Obtain the natural modal frequencies and modal orders of the motor stator or stator-casing system, and establish a modal database. Modal information can be obtained through finite element modal analysis or modal testing, and the natural frequency range of each mode is recorded.

[0043] By establishing a modal database of the stator or stator-casing system, the inherent vibration characteristics of the motor structure within the target frequency band can be obtained, including the natural frequencies of each mode and their corresponding frequency band ranges. This database provides a structural dynamics benchmark for subsequent eccentricity detection, enabling matching analysis between the electromagnetic excitation caused by eccentricity and the structural modes. This allows for the identification of eccentricity features amplified by resonance effects, improving the targeting and reliability of the detection.

[0044] Step S3: Construct an air gap magnetic permeability modulation model caused by rotor eccentricity. Obtain the eccentricity candidate feature set by performing two-dimensional Fourier decomposition of the radial electromagnetic force wave in terms of spatial angle and time.

[0045] like Figure 2 As shown, rotor eccentricity includes three forms: static eccentricity, dynamic eccentricity, and mixed eccentricity. Air gap length calculation models for uniform air gap, static rotor eccentricity, dynamic rotor eccentricity, and mixed eccentricity PMSMs are established in the stator coordinate system. The air gap length when the rotor is not eccentric is a constant value δ0, and the air gap permeability... As shown in the following formula:

[0046] When the motor rotor has static eccentricity, the air gap length at different positions in the air gap is only related to the position angle θ, and the air gap permeability λ(θ,t) can be regarded as a function of the position angle θ. When dynamic eccentricity occurs, the air gap permeability is a two-dimensional function λ(θ,t) of position θ and time t. Therefore, static eccentricity can be regarded as a special case of dynamic eccentricity (i.e., t=0 in the air gap permeability function of dynamic eccentricity). When the motor rotor has mixed eccentricity, it will have the characteristics of both static and dynamic eccentricity.

[0047] A normal motor has a uniform air gap and a stator geometric center O. s With the rotor geometric center O r The rotors coincide, and their rotation centers are also O. r δ0 is the uniform air gap length of a normal motor, R is the stator inner diameter, r is the rotor outer diameter, and θ is the mechanical angle. Given the mechanical angular velocity, consider the air gap permeability of a uniform air gap under the condition of stator slotting. It can be obtained from the following formula:

[0048] Let the average air gap be Circumferential angle is The time is The mechanical angular velocity is eccentricity is The eccentricity is The air gap length can then be parameterized in the following form: Static eccentricity:

[0049] Dynamic eccentricity:

[0050] Mixed eccentricity:

[0051] The above model is used to clarify the spatial / temporal modulation relationship of eccentricity on the air gap, providing a mechanistic basis for the subsequent enhancement of electromagnetic force wave sidebands and resonance caused by eccentricity.

[0052] Since "modal resonance-based" detection requires knowledge of the inherent modal frequencies and modal orders of the motor structure, this invention can obtain modal information and form a modal database through one or a combination of the following two methods. ,in For modal index, For the natural frequency, The bandwidth of this mode (determined by damping or recognition error). This refers to mode shape or mode order information. For example... Figure 3 As shown, a three-dimensional finite element modal model of the stator and housing as a whole is established, and boundary conditions consistent with those of the actual assembly are applied to calculate the natural modal frequencies in the target frequency band. And the corresponding modal characteristics (mode order). For example... Figure 4 As shown, measuring points are arranged on the outer surface of the motor stator / housing. Modal testing is performed using hammer impact or a vibrator to collect the frequency response function and identify the natural frequencies. This method is used to verify or update finite element results, making the modal database more closely reflect reality.

[0053] Rotor eccentricity leads to air gap permeability modulation, thereby introducing new spatial orders and frequency sideband components into the radial electromagnetic force. To establish prior features that can be used for detection, this embodiment is based on radial electromagnetic force waves. Spatiotemporal analysis yielded an eccentric "fingerprint": When the rotor is statically eccentric, the stator geometric center is O. s Rotor geometric center O r0 An offset occurs, i.e., with O s No longer overlapping, rotor rotation center O r With O r0 coincide. δ e This represents the eccentric distance, which is O. s With O r0 The distance between them, ε=δ e / δ0 represents the eccentricity. δ(θ,t) is the air gap length at different air gap positions after static eccentricity, which can be expressed as:

[0054] Since the air gap permeability is positively correlated with the reciprocal of the air gap length, the air gap permeability when the rotor is statically eccentric during stator slotting is:

[0055] Using the Maclaurin expansion, we get (ignoring higher-order components of degree two or above):

[0056] When the rotor is dynamically eccentric, the stator geometric center is O. s Rotor rotation center O r With O s Overlap, rotor geometric center offset to O r0 O r1 The rotor's geometric center at time t is O r0 Move to O r1 δ e This represents the eccentric distance, which is O. s With O r0 The distance between them, ε=δ e / δ0 represents the eccentricity. The air gap length at this point can be expressed as a function of time, where δ(θ,t) is the air gap length at different times and positions after dynamic eccentricity, i.e.:

[0057] In the formula, f m This refers to the mechanical frequency.

[0058] Considering the stator slotting, the air gap permeability due to rotor dynamic eccentricity is:

[0059] Similarly, it can be further simplified to:

[0060] When the rotor is mixed with eccentricity, the stator geometric center is O. s Rotor rotation center O r relative to O s An offset also occurred, with the rotor's geometric center shifting to O. r0 O r1 The rotor's geometric center at time t is O r0 Move to O r1 At this point, the eccentricity under mixed eccentricity is composed of a combination of static and dynamic eccentricity, possessing characteristics of both static and dynamic eccentricity. δ e Denotes the eccentric distance, ε=δ e / δ0 represents the eccentricity. The air gap length at this point can also be expressed as a function of time:

[0061] In the formula 0 <f m1 <f m Similarly, the expression for the air gap permeability under mixed eccentricity is obtained as follows:

[0062] By comparing radial electromagnetic force waves under uniform air gap and different eccentricity conditions, it can be observed that eccentricity causes asymmetric enhancement of the force wave distribution and an increase in local peak values. This result demonstrates that eccentricity does indeed alter the spatial distribution of radial electromagnetic excitation, laying the foundation for subsequent response enhancement.

[0063] Furthermore, in order to separate the components of each order from the spatial distribution, the following steps are taken: Perform two-dimensional Fourier decomposition:

[0064] in For analysis window length. Two-dimensional spectrum. The spectral peak positions correspond to the spatial order and frequency of the electromagnetic force wave, and the peak amplitude reflects the intensity of that component. Finally, the aggregation / sidebanding characteristics of the two-dimensional spectral peaks under eccentric conditions are used to form a set of eccentric candidate features:

[0065] in, This is the set of eccentric candidate features.

[0066] Step S4: Perform spectral analysis on the structural response signal to obtain the power spectrum, and calculate the frequency band enhancement characteristic within the modal frequency band.

[0067] Vibration acceleration and / or noise sound pressure are used as detection signals. The data acquisition objects can be the surface acceleration of the casing (accelerometer) and near-field / far-field sound pressure (microphone), and the rotational speed is collected simultaneously for order tracking or operating condition normalization.

[0068] For the acquired signal Spectral analysis is performed to obtain the amplitude spectrum or power spectrum. For each natural frequency in the modal database In its frequency band window Internal structural modal band enhancement feature quantity, wherein the band energy is:

[0069] in, For frequency band energy; Power spectrum; For each natural frequency in the modal database; The bandwidth of the mode.

[0070] The peak value of the frequency band is:

[0071] in, Peak value in the frequency band; The normalized ratio of the relative health baseline is:

[0072]

[0073] in, The normalized ratio of the frequency band energy relative to the healthy baseline; The normalized ratio of the frequency band peak value relative to the healthy baseline; , These are reference values ​​for a healthy state.

[0074] Step S5: Match the eccentric candidate feature set with the frequency band enhancement feature quantity, determine whether eccentricity exists through the preset eccentricity determination rule, and output the eccentricity type and eccentricity degree evaluation result.

[0075] Compared to the uniform air gap condition, the eccentric condition exhibits significant enhancement of vibration and noise spectrum peaks in certain frequency bands. This enhancement is more prominent near the intrinsic modes, reflecting the amplification effect of "eccentric excitation-modal resonance," and thus can be used as a highly sensitive feature for eccentricity detection.

[0076] eccentric candidate feature set Modal frequency band enhancement features Perform matching and construct bias determination rules: If a certain mode exists With a certain eccentric force wave characteristic ,satisfy:

[0077] And the corresponding modal frequency band enhancement index meets the threshold condition: or

[0078] If a modal resonance enhancement response related to eccentricity is detected, the detection conclusion "rotor eccentricity exists" will be output.

[0079] For eccentricity types, if the main manifestation is spatial order sideband enhancement and the frequency shift feature is not obvious, it is biased towards static eccentricity; if a frequency shift sideband related to the mechanical frequency appears and causes enhancement of multiple modal frequency bands, it is biased towards dynamic eccentricity; if both types of features exist at the same time, it is determined to be mixed eccentricity.

[0080] For eccentricity estimation, under small eccentricity conditions, the amplitude of the sideband excitation introduced by eccentricity is related to the eccentricity. It exhibits monotonic correlation. The mapping relationship can be obtained through calibration:

[0081] in It can be a linear / piecewise linear / table lookup or regression model. The final output is an estimate of the degree of eccentricity or an estimation interval, and a reliability evaluation can be provided.

[0082] In the embodiment, tests were conducted on the uniform air gap and eccentric prototypes under the same rotational speed / load conditions, and the casing acceleration and noise signals were collected and calculated. .like Figure 5 As shown, under no-load conditions, regardless of the motor speed, the vibration acceleration and noise of a healthy motor with a uniform air gap are generally slightly less than those of a dynamically eccentric motor. Furthermore, it is noted that the noise of the dynamically eccentric motor is higher than that of the healthy motor with a uniform air gap at the second-order modal frequency. This is mainly because even when the motor is running under no-load control by the frequency converter, there is still a certain current in its stator armature winding, and the dynamic eccentricity exists in the (0, 24f)... m The (2, 26f) order electromagnetic force wave is introduced near the vicinity of the electromagnetic force wave. mThe second-order sideband component will cause greater vibration at the second-order mode. Whether at the rated speed of 3000 r / min or 1500 r / min, the overall vibration of the dynamic eccentric motor is greater than that of a normal motor with a uniform air gap at the same speed. Furthermore, comparing the vibration acceleration spectra of the same motor at different speeds reveals that the vibration of the uniform air gap motor at its rated speed is significantly greater than that at 1500 r / min, meaning that the vibration increases significantly with increasing speed. Similarly, the vibration acceleration amplitude of the dynamic eccentric motor also increases significantly with increasing speed, especially at the mechanical frequency f. m Vibration at the rated speed f m The vibration acceleration amplitude at f is approximately 1500 r / min. m The vibration amplitude was several times that of the motor. In the noise spectrum at different speeds under inverter power supply conditions, it was noted that both normal motors with uniform air gaps and dynamically eccentric rotor motors generated significant vibration noise near the switching frequency of 10kHz and twice the switching frequency of 20kHz. Furthermore, due to the introduction of sideband electromagnetic force wave components near the switching frequency and twice the switching frequency by the rotor's dynamic eccentricity, the electromagnetic force wave components near the relevant mode order (e.g., 8th order) increased, resulting in even more pronounced vibration noise near the relevant frequencies.

[0083] The eccentric prototype exhibits significant spectral peak enhancement near certain intrinsic mode frequency bands, leading to... and normalization indicators The value is significantly higher than the healthy baseline. Based on the above matching criteria, reliable detection of rotor eccentricity can be achieved, and the eccentricity type and degree can be further output.

[0084] Example 2 This embodiment discloses a permanent magnet motor rotor eccentricity detection system based on modal resonance; like Figure 6 As shown, a permanent magnet motor rotor eccentricity detection system based on modal resonance includes: The signal acquisition module is configured to: acquire the motor operating status and acquire the structural response signals during the motor operation process; The modal database construction module is configured to: establish a modal database for the stator or stator-casing system, and obtain the natural frequencies and frequency bands of each mode; The eccentricity candidate feature set acquisition module is configured to: construct an air gap magnetic permeability modulation model caused by rotor eccentricity, and obtain the eccentricity candidate feature set by performing two-dimensional Fourier decomposition of the radial electromagnetic force wave in terms of spatial angle and time. The feature extraction module is configured to: perform spectral analysis on the structural response signal to obtain the power spectrum, and calculate the frequency band enhancement feature quantity within the modal frequency band; The matching and determination module is configured to: match the eccentric candidate feature set with the frequency band enhancement feature quantity, determine whether eccentricity exists through preset eccentricity determination rules, and output the eccentricity type and eccentricity degree evaluation results.

[0085] Example 3 The purpose of this embodiment is to provide a computer-readable storage medium.

[0086] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in Example 1.

[0087] Example 4 The purpose of this embodiment is to provide an electronic device.

[0088] An electronic device includes a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in Embodiment 1.

[0089] The steps and methods involved in the apparatuses of Embodiments 2, 3, and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0090] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0091] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance, characterized in that, include: Acquire the motor's operating status and collect structural response signals during motor operation; Establish a modal database for the stator or stator-casing system to obtain the natural frequencies and frequency bands of each mode; A model for air gap magnetic permeability modulation caused by rotor eccentricity is constructed. By performing two-dimensional Fourier decomposition of the radial electromagnetic force wave in terms of spatial angle and time, a set of candidate features for eccentricity is obtained. The power spectrum is obtained by performing spectral analysis on the structural response signal, and the frequency band enhancement characteristic is calculated within the modal frequency band. The eccentricity candidate feature set is matched with the frequency band enhancement feature quantity, and the existence of eccentricity is determined by the preset eccentricity determination rule. The eccentricity type and eccentricity degree evaluation results are then output.

2. The method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in claim 1, characterized in that, The motor operating state includes at least one of speed, load, or electromagnetic torque; The structural response signals during the operation of the motor include at least the vibration acceleration signal and noise sound pressure signal at the stator or housing.

3. The method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in claim 1, characterized in that, A model for air gap magnetic permeability modulation caused by rotor eccentricity is constructed. By performing two-dimensional Fourier decomposition of the radial electromagnetic force wave in terms of spatial angle and time, a set of candidate eccentricity features is obtained, including: For different eccentric forms, corresponding mathematical models of air gap length and air gap magnetic permeability are established to clarify the temporal control mechanism of eccentricity on the air gap magnetic field. Based on the constructed model, the sideband characteristics introduced by rotor eccentricity in radial electromagnetic force waves are analyzed, including additional components in spatial order, modulation sidebands in time frequency and their correlation characteristics with mechanical frequency. By performing two-dimensional Fourier decomposition on the radial electromagnetic force wave along both spatial angle and time dimensions, the characteristic spectral peak distributions corresponding to different eccentric forms are extracted, forming a set of eccentric candidate features containing the characteristic patterns of each eccentric type and their corresponding spatial order-frequency coordinates.

4. The method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in claim 1, characterized in that, Spectral analysis is performed on the structural response signal to obtain the power spectrum, and the frequency band enhancement characteristics are calculated within the modal band, including: Spectral analysis of the acquired signal yields the amplitude spectrum or power spectrum; For each intrinsic frequency in the modal database, a modal band enhancement feature is constructed within its band window. The band enhancement feature includes band energy, band peak value, and normalized ratio relative to the healthy baseline.

5. The method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in claim 4, characterized in that, The frequency band energy is: in, For frequency band energy; Power spectrum; For each natural frequency in the modal database; The bandwidth of the mode; The peak value of the frequency band is: in, Peak value in the frequency band; The normalized ratio of the relative health baseline is: in, The normalized ratio of the frequency band energy relative to the healthy baseline; The normalized ratio of the frequency band peak value relative to the healthy baseline; , These are reference values ​​for a healthy state.

6. The method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in claim 1, characterized in that, Matching the eccentricity candidate feature set with the frequency band enhancement feature quantity, and determining whether eccentricity exists through preset eccentricity determination rules, includes: The real-time extracted frequency band enhancement features are matched with the set of eccentricity candidate features, and the matching degree between each candidate feature and the current response is calculated. If the matching degree exceeds a set threshold, and the enhancement feature meets a preset amplitude or energy condition within the corresponding modal frequency band, rotor eccentricity is determined to exist. Specifically: If a certain mode exists With a certain eccentric force wave characteristic , The spatial order of the radial electromagnetic force wave; satisfying And the corresponding modal frequency band enhancement index meets the threshold condition. or If so, it is determined that there is rotor eccentricity.

7. The method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in claim 1, characterized in that, The criteria for determining the eccentricity type are: If the frequency band enhancement feature is mainly manifested as spatial order sidebands and does not shift significantly with rotational speed, it is determined to be static eccentricity; If the frequency band enhancement feature exhibits a frequency shift sideband related to the mechanical frequency and affects multiple modal frequency bands, it is determined to be dynamic eccentricity; If it simultaneously possesses spatial order sideband and frequency shift sideband characteristics, it is determined to be a mixed eccentricity.

8. A permanent magnet motor rotor eccentricity detection system based on modal resonance, characterized in that, include: The signal acquisition module is configured to: acquire the motor operating status and acquire the structural response signals during the motor operation process; The modal database construction module is configured to: establish a modal database for the stator or stator-casing system, and obtain the natural frequencies and frequency bands of each mode; The eccentricity candidate feature set acquisition module is configured to: construct an air gap magnetic permeability modulation model caused by rotor eccentricity, and obtain the eccentricity candidate feature set by performing two-dimensional Fourier decomposition of the radial electromagnetic force wave in terms of spatial angle and time. The feature extraction module is configured to: perform spectral analysis on the structural response signal to obtain the power spectrum, and calculate the frequency band enhancement feature quantity within the modal frequency band; The matching and determination module is configured to: match the eccentric candidate feature set with the frequency band enhancement feature quantity, determine whether eccentricity exists through preset eccentricity determination rules, and output the eccentricity type and eccentricity degree evaluation results.

9. A computer-readable storage medium having a program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in any one of claims 1-7.

10. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the method for detecting rotor eccentricity of a permanent magnet motor based on modal resonance as described in any one of claims 1-7.

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