Permanent magnet motor modal parameter automatic identification method

Abstract

The present application belongs to the technical field of permanent magnet motor modal parameter identification, and discloses a kind of permanent magnet motor modal parameter automatic identification method, comprising S1, the inherent electromagnetic force in motor is regarded as electromagnetic excitation source;S2, the acceleration data of vibration sensor on the surface of stator is obtained;S3, the inherent frequency and damping parameter are obtained based on fourier analysis method;S4, the mode shape parameter is obtained based on two-dimensional fourier analysis method;S5, the actual modal data parameter is obtained based on modal verification criterion.The present application utilizes the electromagnetic excitation force source of permanent magnet motor itself, without hammer or exciter, reduces the cost of system test, realizes the modal parameter test of low cost and wide frequency range;And realizes modal parameter automatic identification, solves the problem of existing hammer excitation band limitation and modal parameter identification frequency band limitation, can effectively guide the working frequency and operating condition of motor.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of permanent magnet motor modal parameter identification, in particular to a permanent magnet motor modal parameter automatic identification method. BACKGROUND

[0002] The permanent magnet motor stator structure modal directly affects the electromagnetic vibration noise level of the motor. The modal is the inherent vibration characteristic of the stator structure, each modal corresponds to a specific natural frequency, damping ratio and modal shape, which can be used to guide the optimization of the motor structure design, thereby avoiding the resonance of the structure and the excitation source and improving the smoothness of the motor operation.

[0003] At present, in order to realize the identification of motor modal parameters, the commonly used motor modal characteristic test method is the force hammer impact excitation method, the working principle of which is: the force hammer is knocked on the surface of the permanent magnet motor stator shell, the impact pulse of the force hammer acts on the stator structure, which is equivalent to applying a certain frequency range of excitation force to the motor to be tested. The frequency sweeping process of the sinusoidal excitation force can be completed by one knock, and the vibration acceleration of the stator surface is collected. Through the frequency spectrum analysis of the vibration response, the natural frequency of the motor system can be obtained. However, this method has the following problems:

[0004] 1. High cost, whether using a force hammer or an exciter, the cost is high, which increases the test cost;

[0005] 2. Bandwidth limitation, the effective frequency range of the impact pulse of the force hammer is limited by the type of the force hammer, so that the natural frequency in a wide frequency range cannot be measured. SUMMARY

[0006] The present application aims to provide a permanent magnet motor modal parameter automatic identification method, which uses the electromagnetic excitation force source of the permanent magnet motor itself, obtains the frequency response function curve based on the Fourier analysis method, extracts the natural frequency and damping parameter, obtains the mode shape parameter based on the two-dimensional Fourier analysis method, removes the false modal based on the modal verification criterion, and obtains the actual modal data parameter. This method does not need a force hammer or an exciter, realizes low-cost and wide-frequency-range modal parameter testing, and realizes automatic identification of modal parameters, solving the problems of excitation frequency band limitation of the existing force hammer and limitation of the modal parameter identification frequency range.

[0007] In order to achieve the above purpose, the present application provides the following technical scheme:

[0008] A permanent magnet motor modal parameter automatic identification method, comprising the following steps:

[0009] S1, the inherent electromagnetic force in the motor is used as an electromagnetic excitation source;

[0010] S2, based on the fact that the motor works in a stable working condition, the acceleration data of the vibration sensor on the stator surface is obtained.

[0011] S3, frequency domain processing of the vibration signal measured by the single vibration sensor based on the Fourier analysis method to obtain a frequency response function curve, and extracting the natural frequency and damping parameter;

[0012] S4, data processing of the vibration signal measured by each sensor on the surface of the stator casing based on the two-dimensional Fourier analysis method to obtain a mode shape parameter;

[0013] S5, verifying the frequency, damping and mode shape based on the modal verification criterion, removing the false mode, and obtaining the actual modal data parameter.

[0014] Further, in S1, the acquisition method of the electromagnetic excitation source is: when the motor is stably working at a stable speed and constant torque, considering mechanical error, a time-space frequency-order electromagnetic excitation force source is generated in the motor air gap; the motor electromagnetic force contains 1, 2, 3, 4 and other orders of spatial harmonics and time harmonics of current frequency multiples. These excitation sources are used as the excitation source of the motor structure excitation, and the calculation model is as follows:

[0015] f r,PM (θ,t)=f rad,r (θ,t)+f r,PM2 (θ,t)+f r,PM3 (θ,t)

[0016]

[0017]

[0018]

[0019] In the formula, f r,PM is the electromagnetic force density in the permanent magnet motor, f rad,r is the motor electromagnetic force density without eccentricity, f r,PM2 and f r,PM3 are the electromagnetic force densities generated after the eccentricity of the stator and rotor, p is the number of pole pairs, Z is the number of slots, θ is the rotor position, ω is the rotor rotation angular frequency, FF r is the r-order radial electromagnetic force amplitude, Fm n represents the n-order harmonic magnetic motive force, Λ0 is the average magnetic guide, ξ represents the eccentricity of the stator and rotor, t is the time, k, n1, and n2 represent the harmonic coefficients, k=0, 1, 2, 3…, n1, n2=1, 3…

[0020] Further, in S2, the stable working condition of the motor is constant speed and constant torque;

[0021] The acceleration data of the vibration sensor reflects the electromagnetic vibration of the motor, which is specifically shown as:

[0022] Based on the electromagnetic force received by the motor stator, the stator generates electromagnetic vibration, the vibration sensor collects the vibration acceleration signal on the surface of the motor stator, processes and records the vibration amplitude of the motor at the slot frequency, wherein the slot frequency is the product of the slot number and the rotor frequency; When the frequency and order of the electromagnetic force are close to the natural frequency and mode shape of the motor, resonance will be caused, at this time, the surface of the motor will produce significant vibration; Increase the motor speed, measure the electromagnetic vibration of the motor at different speeds, and record the vibration amplitude at the slot frequency.

[0023] Further, in S3, the method for obtaining the natural frequency and damping parameter based on the Fourier analysis method is:

[0024] A1, intercepting the time domain vibration acceleration data of the permanent magnet motor current period or integer multiple thereof;

[0025] A2, Fourier decomposition is performed on the time domain acceleration data to obtain frequency domain data of vibration;

[0026] A3, the natural frequency of the motor is obtained by peak value method, and the damping parameter of the motor is solved by half power point method.

[0027] Further, in S4, the method for obtaining the mode shape based on the two-dimensional Fourier analysis method is:

[0028] B1, intercepting the time domain vibration acceleration data of each sensor of the motor in one cycle of the permanent magnet motor current period or integer multiple thereof;

[0029] B2, two-dimensional Fourier decomposition is performed on the time domain acceleration data to obtain frequency domain-order data of vibration;

[0030] B3, extracting the mode shape information at the natural frequency.

[0031] Further, in S5, the actual modal data parameters include frequency, damping and mode shape.

[0032] The beneficial effects of the technical scheme are: the permanent magnet motor itself is used as the electromagnetic excitation force source, without the need for a force hammer or a vibration exciter, the cost of system testing is reduced, the modal parameter testing with low cost and wide frequency range is realized, the identification range of modal frequency is improved; and the modal parameter automatic identification is realized, the problems of the excitation frequency band limitation of the existing force hammer and the limitation of the modal parameter identification frequency band are solved, and the working frequency and operation condition of the motor can be effectively guided. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a system block diagram of the permanent magnet motor modal parameter automatic identification method of the application;

[0034] Figure 2 It is the modal parameter measured in the experiment based on the permanent magnet motor modal parameter automatic identification method of the application;

[0035] Figure 3 Figure 1 is a comparison chart of modal parameters measured by an experimental modal parameter automatic identification method of a permanent magnet motor according to the present application and force hammer experimental data. DETAILED DESCRIPTION

[0036] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments:

[0037] As shown in Figure 1, an automatic identification method of modal parameters of a permanent magnet motor includes the following steps: Figure 1

[0038] S1, the electromagnetic force inherent in the motor is taken as an electromagnetic excitation source; wherein the acquisition method of the electromagnetic excitation source is: when the motor is stably working at a stable speed and constant torque, considering mechanical errors, a time-space frequency-order electromagnetic excitation force source is generated in the motor air gap; the motor electromagnetic force contains 1, 2, 3, 4 order spatial harmonics and time harmonic electromagnetic force related to current frequency multiples, these excitation force sources are taken as the excitation source of motor structure excitation, and the calculation model is as follows:

[0039] f r,PM (θ,t)=f rad,r (θ,t)+f r,PM2 (θ,t)+f r,PM3 (θ,t)

[0040]

[0041]

[0042]

[0043] In the formula, f r,PM is the electromagnetic force density in the permanent magnet motor, f rad,r is the motor electromagnetic force density without eccentricity, f r,PM2 and f r,PM3 are the electromagnetic force densities generated after the eccentricity of the stator and rotor, p is the number of pole pairs, Z is the number of slots, θ is the rotor position, ω is the rotor rotation angular frequency, FF r is the r-order radial electromagnetic force amplitude, Fm n represents the n-order harmonic magnetic motive force, Λ0 is the average magnetic conductance, ξ represents the eccentricity of the stator and rotor, t is the time, k, n1, and n2 represent harmonic coefficients, k=0, 1, 2, 3…, n1, n2=1, 3…;

[0044] ​S2. Based on the stable operating condition of the motor with constant speed and constant torque, the acceleration data of the vibration sensor around the stator surface is obtained. The acceleration data of the vibration sensor reflects the electromagnetic vibration of the motor. Specifically, based on the electromagnetic force acting on the motor stator, the stator generates electromagnetic vibration. The vibration sensor collects the vibration acceleration signal of the motor stator surface, processes and records the motor vibration amplitude at the slot frequency, where the slot frequency is the number of slots multiplied by the rotor frequency. When the frequency and order of the electromagnetic force are close to the natural frequency and mode shape of the motor, resonance will be caused. At this time, the motor surface will generate significant vibration.

[0045] Increase the motor speed, measure the electromagnetic vibration of the motor at different speeds, and record the vibration amplitude at the slot frequency. When the frequency meets the maximum modal frequency range, connect the slot frequency electromagnetic vibration amplitudes at different speeds to form a curve, thereby obtaining the frequency response function.

[0046] S3. Based on the Fourier analysis method, the vibration signal measured by a single vibration sensor is processed in the frequency domain to obtain the frequency response function curve, and the natural frequency and damping parameters are extracted. The specific method is as follows:

[0047] A1. Extract time-domain vibration acceleration data of the permanent magnet motor current period or an integer multiple thereof;

[0048] A2. Perform Fourier decomposition on the acceleration data in the time domain to obtain the frequency domain data of the vibration;

[0049] A3. The natural frequency of the motor is obtained by the peak method, and the damping parameters of the motor are solved by the half-power point method.

[0050] S4. Based on the two-dimensional Fourier analysis method, the vibration signals measured by various sensors on the surface of the stator housing are processed to obtain the mode shape parameters. The specific method is as follows:

[0051] B1. Extract time-domain vibration acceleration data from each sensor for one revolution of the permanent magnet motor current cycle or an integer multiple thereof;

[0052] B2. Perform two-dimensional Fourier decomposition on the acceleration data in the time domain to obtain the frequency domain-order data of the vibration.

[0053] B3. Extract mode shape information at the natural frequency;

[0054] S5. Based on the modal verification criteria, verify the frequency, damping and mode shape respectively, remove spurious modes, and obtain the actual modal data parameters, including frequency, damping and mode shape.

[0055] like Figure 2 , Figure 3As shown in Table 1, the permanent magnet motor modal parameters measured based on the method provided by the application are basically consistent with the modal parameters analyzed by the force hammer method, the frequency error is within 3%, the damping ratio error is within 6.8%, which is within the engineering allowable range, and the effectiveness of the permanent magnet motor modal parameters obtained by the method is verified.

[0056] Table 1 Comparison of permanent magnet motor modal parameters and modal parameters analyzed by force hammer method

[0057]

[0058] The application does not need a force hammer or an excitation source such as an exciter, greatly reducing the cost of system testing, and in addition, without a force hammer or an exciter, the identification range of modal frequency is improved, which can effectively guide the working frequency and operating condition of the motor.

[0059] The above is only an embodiment of the application, and common knowledge such as specific technical solutions or characteristics in the scheme is not described in detail. It should be pointed out that for those skilled in the art, without departing from the technical solutions of the application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the application, and these will not affect the effect and practicality of the application. The protection scope of the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A permanent magnet motor modal parameter automatic identification method, characterized in that, The method comprises the following steps: S1, the electromagnetic force inherent in the motor is taken as an electromagnetic excitation source; S2, based on the motor working in a stable working condition, acceleration data of a vibration sensor on the surface of the stator is obtained; S3, based on a Fourier analysis method, frequency domain processing is performed on the vibration signal measured by the single vibration sensor to obtain a frequency response function curve, and inherent frequency and damping parameters are extracted; S4, based on a two-dimensional Fourier analysis method, data processing is performed on the vibration signals measured by each sensor on the surface of the stator casing to obtain vibration mode parameters; S5, based on a modal verification criterion, frequency, damping and vibration mode are verified respectively, false modes are removed, and actual modal data parameters are obtained; In S1, the acquisition method of the electromagnetic excitation source is as follows: when the motor works stably at a stable speed and a constant torque, considering mechanical errors, a time-space frequency-order electromagnetic excitation force source is generated in the motor air gap; the motor electromagnetic force contains various order space harmonics and time harmonics electromagnetic force related to current frequency multiples, these excitation sources are taken as the excitation source of the motor structure excitation, and the calculation model is as follows: wherein f r,PM is the electromagnetic force density in the permanent magnet motor, f rad,r is the electromagnetic force density in the motor without eccentricity, f r,PM2 and f r,PM3 is the electromagnetic force density generated after the eccentricity of the stator and rotor, p is the number of pole pairs, Z is the number of slots, is the rotor position, is the rotor rotation angular frequency, FF r is the r-th order radial electromagnetic force amplitude, Fm n denotes n the sub-harmonic magnetic motive force, is the average magnetic permeance, denotes the eccentricity of the stator and rotor, t is the time quantity, k n 1, and n 2 denote the harmonic coefficients, k = 0, 1, 2, 3…, n 1 ,n 2 = 1, 3…​ 2. The method of claim 1, wherein: In S2, the stable working condition of the motor is constant speed and constant torque; The acceleration data of the vibration sensor reflects the electromagnetic vibration of the motor, which is specifically as follows: Based on the electromagnetic force received by the motor stator, the stator generates electromagnetic vibration, the vibration sensor is used to collect the vibration acceleration signal on the surface of the motor stator, and the motor vibration amplitude at the slot frequency is processed and recorded, wherein the slot frequency is the product of the slot number and the rotor frequency; when the frequency and order of the electromagnetic force are close to the inherent frequency and vibration mode of the motor, resonance will be caused, at this time, significant vibration will be generated on the surface of the motor; the motor speed is increased, the motor electromagnetic vibration under different speeds is measured, and the vibration amplitude at the slot frequency is recorded.

3. The method of claim 1, wherein: In S3, the method for obtaining the inherent frequency and damping parameters based on the Fourier analysis method is as follows: A1, the time domain vibration acceleration data of the permanent magnet motor current period or integer multiple thereof is intercepted; A2, the Fourier decomposition is performed on the time domain acceleration data to obtain the frequency domain data of the vibration; A3, the inherent frequency of the motor is obtained by the peak value method, and the damping parameter of the motor is obtained by the half power point method.

4. The method of claim 1, wherein: In S4, the method for obtaining the vibration mode based on the two-dimensional Fourier analysis method is as follows: B1, the time domain vibration acceleration data of each sensor of the motor one cycle of the permanent magnet motor current period or integer multiple thereof is intercepted; B2, the two-dimensional Fourier decomposition is performed on the time domain acceleration data to obtain the frequency domain-order data of the vibration; B3, the vibration mode information at the inherent frequency is extracted.

5. The method of claim 1, wherein: In S5, the actual modal data parameters include frequency, damping and vibration mode.

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