CN115856621A - Asynchronous motor rotor broken bar fault diagnosis method and system - Google Patents
Asynchronous motor rotor broken bar fault diagnosis method and system Download PDFInfo
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- CN115856621A CN115856621A CN202211552020.0A CN202211552020A CN115856621A CN 115856621 A CN115856621 A CN 115856621A CN 202211552020 A CN202211552020 A CN 202211552020A CN 115856621 A CN115856621 A CN 115856621A
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Abstract
The invention relates to a method and a system for diagnosing a broken rotor bar fault of an asynchronous motor. The system comprises two parts: the edge side is provided with a vibration sensor and a collector at the position of the asynchronous motor to be detected and a remote server. The method is realized through far edge cooperation: the method comprises the steps that an edge side collector acquires vibration waveform data of a motor at regular time; calculating the actual rotating speed of the motor according to the vibration waveform, the power frequency of the motor and the number of pole pairs of the motor, which are issued by the server; calculating pole passing frequency according to the actual rotating speed of the motor, the power supply frequency of the motor and the pole pair number; segmenting the first ten times of frequency conversion of the motor on a speed frequency spectrum, carrying out envelope demodulation processing on each segment of frequency spectrum, and calculating the characteristic frequency position of each envelope spectrum; and comparing the pole passing frequency with the calculated ten envelope spectrum characteristic frequencies to judge whether the motor has the rotor broken bar fault. The invention collects the vibration signal and diagnoses the mechanical and electrical fault types, and has low monitoring cost and high efficiency.
Description
Technical Field
The invention relates to a method and a system for diagnosing a broken bar fault of an asynchronous motor rotor, belongs to the field of motor state monitoring and fault diagnosis, and particularly relates to a method and a system for diagnosing a broken bar fault of an asynchronous motor rotor based on a vibration signal.
Background
The asynchronous motor is widely applied as an industrial field host device due to a series of advantages of simple structure, low price, high operation efficiency and the like. The fault types of the motor generally comprise a mechanical fault and an electrical fault, and a vibration sensor, a temperature sensor, a current sensor and the like are required to be installed in a common fault monitoring means. For fault monitoring of motor rotor broken bars, current monitoring and diagnosing methods in the prior art are more, but for some application occasions where only a vibration sensor can be installed and a current sensor cannot be installed, the fault monitoring and diagnosing method has the defect that monitoring and diagnosing cannot be performed.
Disclosure of Invention
The invention aims to provide a method and a system for diagnosing the broken bar fault of an asynchronous motor rotor, which are used for solving the problem that the broken bar fault of the motor rotor is difficult to monitor when a vibration sensor can only be installed at a motor.
In order to achieve the above purpose, the scheme of the invention comprises:
the technical scheme of the method for diagnosing the broken bar fault of the asynchronous motor rotor comprises the steps of obtaining vibration waveform data of an asynchronous motor to be detected; calculating the actual rotating speed of the motor according to the vibration waveform data, the power supply frequency of the motor and the number of pole pairs of the motor; calculating pole passing frequency according to the actual rotating speed of the motor, the power frequency of the motor and the pole number of the motor; segmenting a preset number of frequency multiples of the motor frequency conversion on a speed frequency spectrum, carrying out envelope demodulation processing on the frequency spectrum of each frequency multiple, and calculating the characteristic frequency of each envelope demodulation spectrum; and comparing the pole passing frequency with the calculated ten envelope demodulation spectrum characteristic frequencies to judge whether the motor has the rotor broken bar fault.
The asynchronous motor rotor broken bar fault diagnosis method and system based on the vibration signals can solve the dilemma that a field motor can only be provided with a vibration sensor, but the measurement and diagnosis of the motor rotor broken bar fault are required. Meanwhile, the vibration signal is adopted to diagnose two fault types of machinery and electricity, and the method has the advantages of low monitoring cost and high efficiency.
Further, vibration waveform data is obtained through a vibration speed sensor or the vibration speed sensor; or acquiring a vibration acceleration signal through a vibration acceleration sensor, and performing primary integration on the vibration acceleration signal into a vibration speed signal to acquire vibration waveform data.
The vibration waveform data can be obtained by two sensors, and when the vibration acceleration sensor is used for obtaining the vibration waveform data, signals are required to be integrated to obtain the vibration speed waveform data.
Further, the actual rotating speed of the motor is calculated according to the synchronous rotating speed of the motor and the vibration speed frequency spectrum, and the vibration speed frequency spectrum is obtained from vibration waveform data.
Further, the pole pass frequency = [ (synchronous motor rotation speed-actual motor rotation speed) ÷ 60] × motor pole pair number × 2.
Further, the motor synchronous speed = motor power frequency × 60 ÷ motor pole pair number.
And further, segmenting according to the integer multiple of each integer between 1 and the set number as the center.
The segmentation of the first n frequency multiples of the motor frequency conversion on the speed spectrum is specifically as follows:
frequency band 1: the lower limit is f (1 x-0.8 x) and the upper limit is f (1x + 0.8x), namely [ f0.2x, f1.8x ];
frequency band 2: the lower limit is f (2 x-0.8 x) and the upper limit is f (2x + 0.8x), namely [ f1.2x, f2.8x ];
……
frequency band n: the lower limit is f (nx-0.8 x) and the upper limit is f (nx +0.8 x), namely [ f (n-0.8) x, f (n + 0.8) x ];
wherein 0.8x, 1x, 2x, \ 8230, nx are zero octave, one octave, two octaves, \ 8230, and n octaves of synchronous frequency conversion of the motor, respectively.
Further, the maximum value of the peak value of the spectral line on the envelope demodulation spectrum of the envelope demodulation frequency range after envelope demodulation is used as the characteristic frequency of the envelope demodulation spectrum.
Further, the numerical value comparison is to respectively perform difference between the pole passing frequency and the characteristic frequency on the envelope demodulation spectrums with the set number and take absolute values, and then respectively compare the absolute values with the set values, and when the number smaller than the set values is within a certain range, the motor is judged to have no rotor broken bar fault; otherwise, judging that the motor has a rotor broken bar fault; the set value is a value of a resolution on the frequency spectrum.
Furthermore, the confidence of the judgment result of the motor rotor broken bar fault increases along with the increase of the number of the broken bar fault judgment results smaller than the set value.
The technical scheme of the system for diagnosing the broken bar fault of the asynchronous motor rotor comprises a server at the edge side and the far end of a motor to be detected; the edge side comprises a vibration sensor arranged at the position of a motor bearing and an edge collector connected with the vibration sensor; according to the vibration waveform data obtained by the edge collector, the power frequency of the motor and the logarithm of the motor level, a processor in the edge collector or the server is used for executing instructions so as to realize the method for diagnosing the broken rotor bar fault of the asynchronous motor as claimed in any one of claims 1 to 9.
Drawings
FIG. 1 is a system schematic diagram of an asynchronous motor rotor bar break fault diagnosis method of the present invention;
FIG. 2 is a flow chart of the asynchronous motor rotor bar break fault diagnosis method of the present invention;
FIG. 3 is a frequency spectrum diagram of a vibration velocity waveform of a motor according to an embodiment of the present invention;
fig. 4 is a demodulation spectrum of ten frequency bands of the frequency spectrum division of the vibration speed of the motor according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.
The method comprises the following steps:
the invention relates to a vibration signal-based asynchronous motor rotor broken bar fault diagnosis method, wherein corresponding system hardware components and connection structures are shown in figure 1, and the method comprises the following steps: the device comprises a vibration acceleration sensor and a collector which are arranged on the edge side of the asynchronous motor to be detected, and a server which is positioned at the far end.
The vibration acceleration sensor can be installed at the radial horizontal position and the radial vertical position of the bearing position of the driving end of the motor, and the radial horizontal position and the radial vertical position of the bearing position of the free end of the motor, wherein the installation of the sensors at four positions are listed in the figure and are respectively marked as a sensor 1, a sensor 2, a sensor 3 and a sensor 4. The sensor is connected with the collector through a signal cable, and the collector is in network communication with the server through a 5G, wiFi or RJ45 wired network; the server may be a local area network server or a wide area network cloud server.
As shown in fig. 2, the method for diagnosing the broken rotor bar fault of the asynchronous motor comprises the following steps:
firstly, an edge side collector regularly obtains vibration waveform data meeting the judgment of the broken bar fault of the asynchronous motor rotor; the sensor for collecting vibration waveform data can be a vibration acceleration sensor or a vibration speed sensor; the sampling time for collecting the vibration waveform data is not less than 10 seconds, namely the frequency spectrum resolution is not less than 0.1Hz, and the sampling frequency is not less than 25.6 times of the synchronous rotating speed frequency of the motor.
And secondly, calculating the actual rotating speed of the motor by the edge side collector according to the vibration waveform and the power frequency of the motor issued by the server.
Wherein, the vibration acceleration signal needs to be integrated into a vibration speed signal for one time;
and the actual rotating speed of the motor is calculated according to the synchronous rotating speed and the vibration speed frequency spectrum.
Wherein, the synchronous rotation speed of the motor = the power frequency of the motor × 60 ÷ number of pole pairs of the motor.
And thirdly, calculating the pole passing frequency according to the motor power frequency and the number of pole pairs of the motor, which are transmitted by the motor at the actual rotating speed and the server.
Pole pass frequency fp = [ (motor synchronous rotating speed-motor actual rotating speed) ÷ 60] × motor pole pair number × 2;
fourthly, segmenting the first ten frequencies of the motor frequency conversion on the speed frequency spectrum, carrying out envelope demodulation processing on each segment of frequency spectrum, and calculating the characteristic frequency position of each envelope spectrum;
the specific method for segmenting the first ten times of the motor frequency conversion on the speed spectrum comprises the following steps:
frequency band 1: the lower limit is f (1 x-0.8 x) and the upper limit is f (1x + 0.8x), namely [ f0.2x, f1.8x ];
frequency band 2: the lower limit is f (2 x-0.8 x) and the upper limit is f (2x + 0.8x), namely [ f1.2x, f2.8x ];
frequency band n: the lower limit is f (nx-0.8 x) and the upper limit is f (nx +0.8 x), namely [ f (n-0.8) x, f (n + 0.8) x ];
wherein n =10,0.8x, 1x, 2x, \8230, nx is zero octa-frequency, one-frequency, two-frequency, \8230ofsynchronous frequency conversion of the motor, and n-frequency.
And respectively carrying out envelope demodulation processing on the ten frequency multiplication sections, and taking the maximum value position of the spectrum line peak value on the processed demodulation spectrum as the characteristic frequency, wherein the characteristic frequency is respectively marked as fe1, fe2, \ 8230;, fe10.
Fifthly, comparing the pole passing frequency with the calculated ten envelope spectrum characteristic frequencies, judging whether the motor has a rotor broken bar fault, and calculating a confidence coefficient;
and (3) making a difference between the polar pass frequency and each characteristic frequency on the envelope demodulation spectrum and taking an absolute value to obtain an array with the length of 10 as follows: [ | fe1-fp |, | fe2-fp |, \ 8230 |, fe10-fp | ];
calculating the number of data in the array, wherein the data is smaller than a, and is marked as b, a is a definable decimal, the numerical value of a resolution on a frequency spectrum is taken as a default, and b is an integer within 10;
if b is more than or equal to 0 and less than 2, judging that the motor has no rotor broken bar fault;
if b is more than or equal to 2 and less than or equal to 10, judging that the motor has a rotor broken bar fault;
its confidence, cf =0.6+ (b-2) × 0.1, b ∈ [2,5];
cf＝1.0,b∈[6,10].
and sixthly, uploading the judged broken motor rotor bar fault state and the confidence coefficient thereof to a server-side database by the edge side for system display.
The process of the invention is illustrated below by way of specific examples:
the model number of a certain asynchronous motor is YKK630-4, a fixed frequency motor has power of 1300kW, rated rotation speed of 1490r/min, the number of pole pairs of the motor is 2, synchronous rotation speed of 1500r/min and synchronous rotation frequency of 25Hz. On-site monitoring finds that the vibration speed values of the front end and the rear end of the motor have a gradual rising trend, and then the vibration of the front end and the rear end of the motor is analyzed in detail, so that the diagnosis conclusion is that the motor rotor broken bar fault is obtained.
The sampling parameters of the system edge side collector are as follows: the number of sampling points is 8192 points, and the sampling frequency is 640Hz.
And selecting the measuring position with the maximum vibration in the measuring points at the front end and the rear end of the motor for vibration analysis. The waveform spectrum of the horizontal vibration speed signal at the rear end of the motor is shown in fig. 3.
The actual operating frequency of the motor can be calculated to be 24.92Hz from the frequency spectrum diagram of FIG. 3, i.e. the actual rotating speed is 1495r/min;
the motor pole passing frequency can be calculated according to the basic parameter information of the motor as follows:
fp＝[(1500-1495)÷60]×2×2＝0.33(Hz)
the first ten frequencies of the synchronous frequency conversion of the motor in the spectrogram are segmented, and the characteristic frequency and amplitude of the envelope spectrum corresponding to each frequency band are respectively calculated, as shown in table 1 below. The envelope spectrogram corresponding to each frequency band is shown in fig. 4.
TABLE 1 frequency band division and corresponding table for calculating characteristic frequency and amplitude of envelope spectrum
And (3) making a difference between the polar pass frequency and each characteristic frequency on the envelope demodulation spectrum and taking an absolute value to obtain an array with the length of 10 as follows:
[0.0175,0.0175,0.0175,0.295,0.0175,0.0175,0.0175,0.0175,0.0175,0.0175]；
given a spectral sampling resolution of 640Hz/8192=0.078125, a =0.078125;
if 9 values smaller than a are satisfied in the array, b =9, and therefore it is judged that the motor has a rotor broken bar fault, and the confidence coefficient cf =1.0.
The embodiment of the system is as follows:
the asynchronous motor rotor broken bar fault diagnosis system based on the vibration signal comprises a server at the edge side and the far end of a motor to be detected; the edge side comprises a vibration sensor arranged at the position of a motor bearing and an edge collector connected with the vibration sensor; the edge collector is connected with the server through the Internet; the edge collector executes the asynchronous motor rotor broken bar fault diagnosis method based on the vibration signal according to the obtained vibration waveform data and the motor power supply frequency and the motor grade logarithm transmitted by the server.
In other embodiments, the vibration waveform data obtained by the edge collector may also be transmitted to a server, and the server executes the asynchronous motor rotor broken bar fault diagnosis method of the present invention.
The method for diagnosing the broken bar fault of the asynchronous motor rotor based on the vibration signal is sufficiently clear in the embodiment of the method, and is not described in detail herein.
The above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A method for diagnosing the broken bar fault of an asynchronous motor rotor is characterized by acquiring vibration waveform data of an asynchronous motor to be detected; calculating the actual rotating speed of the motor according to the vibration waveform data, the power supply frequency of the motor and the number of pole pairs of the motor; calculating pole passing frequency according to the actual rotating speed of the motor, the power frequency of the motor and the pole number of the motor; segmenting the preset number of frequency multiplication of the motor frequency conversion on the speed frequency spectrum, carrying out envelope demodulation processing on the frequency spectrum of each frequency multiplication band, and calculating the characteristic frequency of each envelope demodulation spectrum; and comparing the pole passing frequency with the calculated ten envelope demodulation spectrum characteristic frequencies to judge whether the motor has the rotor broken bar fault.
2. The asynchronous motor rotor broken bar fault diagnosis method according to claim 1, characterized in that vibration waveform data is obtained through an or vibration speed sensor; or acquiring a vibration acceleration signal through a vibration acceleration sensor, and performing primary integration on the vibration acceleration signal into a vibration speed signal to acquire vibration waveform data.
3. The method for diagnosing the broken rotor bar fault of the asynchronous motor according to claim 1, wherein the actual rotating speed of the motor is calculated according to the synchronous rotating speed of the motor and a vibration speed frequency spectrum, and the vibration speed frequency spectrum is obtained from vibration waveform data.
4. The method for diagnosing a rotor breaking bar fault of an asynchronous motor according to claim 1, wherein the pole passing frequency = [ (synchronous motor speed-actual motor speed) ÷ 60] x number of pole pairs of the motor x 2.
5. The method for diagnosing a broken rotor bar fault of an asynchronous motor according to claim 3 or 4, characterized in that the motor synchronous rotation speed = motor power frequency x 60 ÷ motor pole pair number.
6. The method for diagnosing the broken bar fault of the asynchronous motor rotor according to claim 1, wherein the segmentation is carried out by taking the integer multiple of each integer between 1 and the set number as the center.
7. The asynchronous motor rotor broken bar fault diagnosis method according to claim 1, characterized in that the maximum value of the peak value of the spectral line on the envelope demodulation spectrum of the envelope demodulation frequency band after envelope demodulation is used as the characteristic frequency.
8. The method for diagnosing the rotor broken bar fault of the asynchronous motor according to claim 1, wherein the numerical comparison is that the pole passing frequency and the characteristic frequency on the envelope demodulation spectrums with the set number are respectively subjected to difference and absolute values are obtained, and then the absolute values are respectively compared with the set value, and when the number smaller than the set value is within a certain range, the occurrence of the rotor broken bar fault of the motor is judged; otherwise, judging that the motor has a rotor broken bar fault; the set value is a value of a resolution on the frequency spectrum.
9. The method for diagnosing the broken bar fault of the asynchronous motor rotor as recited in claim 8, wherein the confidence of the judgment result of the broken bar fault of the motor rotor increases with the increase of the number of the broken bar faults smaller than the set value.
10. A broken bar fault diagnosis system of an asynchronous motor rotor is characterized by comprising a server at the edge side and the far end of a motor to be detected; the edge side comprises a vibration sensor arranged at the position of a motor bearing and an edge collector connected with the vibration sensor; according to the vibration waveform data obtained by the edge collector, the power frequency of the motor and the logarithm of the motor level, a processor in the edge collector or the server is used for executing instructions so as to realize the method for diagnosing the broken rotor bar fault of the asynchronous motor as claimed in any one of claims 1 to 9.
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| CN116448236A (en) * | 2023-06-20 | 2023-07-18 | 安徽容知日新科技股份有限公司 | Edge-end vibration monitoring system and method, and computer-readable storage medium |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116448236A (en) * | 2023-06-20 | 2023-07-18 | 安徽容知日新科技股份有限公司 | Edge-end vibration monitoring system and method, and computer-readable storage medium |
| CN116448236B (en) * | 2023-06-20 | 2023-09-12 | 安徽容知日新科技股份有限公司 | Edge-end vibration monitoring system and method, and computer-readable storage medium |
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