A synchronous machine operating state monitoring device and method
By analyzing the vibration and power signals of permanent magnet synchronous motors, filtering periodic characteristic frequencies and performing noise reduction processing, and combining this with DTW analysis, the problem of inaccurate monitoring caused by environmental noise interference was solved, and accurate assessment of the operating status of permanent magnet synchronous motors was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QINGDAO JINGANG MAGNETIC TECH CO LTD
- Filing Date
- 2025-12-23
- Publication Date
- 2026-07-21
Smart Images
Figure CN121656835B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electronic power technology, and specifically to a device and method for monitoring the operating status of a synchronous motor. Background Technology
[0002] A permanent magnet synchronous motor (PMSM) provides a magnetic field on its rotor using permanent magnets, and its rotor speed is synchronized with the power grid frequency. The operating status of a PMSM can be monitored through vibration monitoring, current monitoring, voltage monitoring, speed monitoring, and rotor position monitoring, thus assessing the motor's health. Since rotor imbalance, bearing damage, and other faults can affect the vibration of the motor's rotor and stator, vibration monitoring is generally used to evaluate the PMSM's operating condition.
[0003] When monitoring the vibration of a permanent magnet synchronous motor to assess its operating status, the collected vibration signals are often affected by interference from external equipment such as mechanical devices, fans, and pumps. Because environmental noise has a large amplitude and is not easily dissipated, it often interferes with the vibration signal of the permanent magnet synchronous motor itself, making it impossible to obtain accurate monitoring results on whether the permanent magnet synchronous motor is operating normally. Summary of the Invention
[0004] This invention provides a device and method for monitoring the operating status of a synchronous motor, to solve the problem of inaccurate monitoring of the operating status of a permanent magnet synchronous motor due to environmental noise interference. The specific technical solution adopted is as follows: In a first aspect, one embodiment of the present invention provides a method for monitoring the operating status of a synchronous motor, the method comprising the following steps: Vibration signals and power at all sampling times within a preset time period are collected at different preset positions of the permanent magnet synchronous motor. Based on the vibration signal of the permanent magnet synchronous motor collected from the same preset location, the spectrum of the permanent magnet synchronous motor is obtained. Based on the distribution of all frequencies contained in the spectrum of the permanent magnet synchronous motor and the amplitude values corresponding to all frequencies, the probability of the dominant frequency of all frequencies contained in the spectrum is determined, and periodic characteristic frequencies are screened. The operating status of the permanent magnet synchronous motor is initially screened using the periodic characteristic frequencies. When the screening result is abnormal, the vibration signal is filtered based on the periodic characteristic frequencies to obtain a denoised vibration signal. The time interval sequence of the permanent magnet synchronous motor is obtained based on the denoised vibration signal, and the power sequence of the permanent magnet synchronous motor is obtained based on the power. The time interval sequence and the power sequence are then standardized. Based on the dynamic time warping (DTW) distance between the standardized time interval sequence and the power sequence, and the changing trends of the two, the rotor offset evaluation value of the permanent magnet synchronous motor is determined. Based on the rotor offset evaluation values of the permanent magnet synchronous motor corresponding to all acquisition positions, the real-time monitoring results of the permanent magnet synchronous motor's operating status are obtained.
[0005] Furthermore, the specific method for determining the probability of the dominant frequency of all frequencies in the spectrum of the permanent magnet synchronous motor based on the distribution of all frequencies contained in the spectrum of the permanent magnet synchronous motor and the amplitude values corresponding to all frequencies includes: The normalized Z-score of all frequencies contained in the spectrum of a permanent magnet synchronous motor is denoted as the significance of overweight and weight loss of the permanent magnet synchronous motor. Let any frequency contained in the spectrum of the permanent magnet synchronous motor be denoted as the target frequency, and let the mean of the amplitudes corresponding to all frequencies contained in the spectrum of the permanent magnet synchronous motor be denoted as the frequency mean of the permanent magnet synchronous motor; let the ratio of the amplitude corresponding to the target frequency to the frequency mean of the permanent magnet synchronous motor be denoted as the first ratio of the target frequency. The probability of the target frequency as the main frequency is determined based on the first ratio of the target frequency and the significance of the overweight and weight loss of the permanent magnet synchronous motor.
[0006] Furthermore, the specific method for determining the probability of the target frequency's dominant frequency based on the first ratio of the target frequency and the significance of the overweight and weight loss of the permanent magnet synchronous motor includes: The product of the first ratio of the target frequency and the significance of the overweight and weight loss of the permanent magnet synchronous motor is denoted as the probability of the main frequency of the target frequency.
[0007] Furthermore, the specific method for filtering periodic characteristic frequencies based on the probability of the dominant frequency is as follows: When the probability of the main frequency is greater than or equal to the preset first threshold, the frequency corresponding to the probability of the main frequency is recorded as the periodic characteristic frequency.
[0008] Furthermore, the specific methods for using the periodic characteristic frequency to perform preliminary screening of the operating status of the permanent magnet synchronous motor and to obtain the denoised vibration signal are as follows: When the sum of the amplitudes corresponding to all periodic characteristic frequencies is less than the ratio of the sum of the amplitudes of the permanent magnet synchronous motor to the preset second threshold, it is determined that the permanent magnet synchronous motor has not experienced rotor offset or rotor instability during the acquisition time period corresponding to the vibration signal, and the permanent magnet synchronous motor is determined to be in good operating condition. When the sum of the amplitudes corresponding to all periodic characteristic frequencies is greater than or equal to the sum of the amplitudes of the permanent magnet synchronous motor, the preliminary screening result is determined to be abnormal. For the abnormal result, the periodic characteristic frequencies are used as parameters of the bandpass filter to perform bandpass filtering on the vibration signal of the permanent magnet synchronous motor to obtain a denoised vibration signal.
[0009] Furthermore, the time interval sequence and the power sequence are standardized, specifically as follows: Calculate the time interval between the acquisition times corresponding to adjacent extreme points in the denoised vibration signal, and arrange them in the order of acquisition times to obtain the original time interval sequence; arrange the power corresponding to the acquisition times in order to obtain the original power sequence; process the original time interval sequence and the original power sequence using the Z-Score normalization method to obtain the normalized time interval sequence and power sequence.
[0010] Furthermore, the determination of the rotor offset evaluation value of the permanent magnet synchronous motor based on the dynamic time warping (DTW) distance between the standardized time interval sequence and the power sequence, and the changing trends of both, includes: The DTW distance between the standardized time interval sequence and the power sequence is calculated, and the DTW distance is mapped to a synchronization coefficient using a negative exponential function. Curve fitting is performed on the standardized time interval sequence and the power sequence respectively to obtain the average slope of the time interval and the average slope of the power. The product of the average slope of the power and the average slope of the time interval is denoted as the fluctuation intensity factor of the permanent magnet synchronous motor.
[0011] Furthermore, the specific method for determining the rotor offset evaluation value of the permanent magnet synchronous motor includes: The product of the fluctuation intensity factor and the synchronization coefficient is denoted as the rotor offset evaluation value of the permanent magnet synchronous motor.
[0012] Furthermore, the specific method for obtaining the real-time monitoring results of the permanent magnet synchronous motor's operating status based on the rotor offset evaluation values of the permanent magnet synchronous motor corresponding to all acquisition positions of the permanent magnet synchronous motor includes: Calculate the arithmetic mean of the rotor offset evaluation values corresponding to all acquisition positions of the permanent magnet synchronous motor, and denote it as the overall severity; calculate the average absolute deviation of the rotor offset evaluation values corresponding to all acquisition positions of the permanent magnet synchronous motor, and denote it as the spatial dispersion; the sum of the overall severity and the spatial dispersion is denoteed as the rotor anomaly evaluation value of the permanent magnet synchronous motor. When the rotor abnormality evaluation value of the permanent magnet synchronous motor is greater than or equal to the preset third threshold, the permanent magnet synchronous motor is judged to be operating abnormally. When the rotor abnormality evaluation value of the permanent magnet synchronous motor is less than the preset third threshold, the permanent magnet synchronous motor is judged to be operating normally.
[0013] Secondly, embodiments of the present invention also provide a synchronous motor operating status monitoring device, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described above.
[0014] The beneficial effects of this invention are: This application evaluates the periodicity of the vibration signal of a permanent magnet synchronous motor (PMSM) affected by frequent periodic overload and weightlessness, based on the characteristic that the rotor in a PMSM exhibits regular overload and weightlessness with each rotation when the rotor is misaligned or unstable. First, it determines the probability of the dominant frequency among all frequencies contained in the PMSM's spectrum. The probability of the dominant frequency is used to evaluate the significance of information about rotor misalignment or instability contained in the PMSM's vibration signal. Then, based on the probability of the dominant frequency, periodic characteristic frequencies are selected, which are the frequencies exhibiting periodic characteristics. Further, based on the periodic characteristic frequencies, the judgment result of the PMSM's rotor operating state is obtained, identifying the rotors with a judgment result indicating rotor misalignment or instability. The noise-reduced vibration signal of the permanent magnet synchronous motor (PMSM) is further analyzed for vibration signals exhibiting periodic characteristics. Based on the clear synchronicity between the power variation trend of the PMSM and the periodic variation trend of the vibration signal, this synchronicity is evaluated to determine the degree of rotor offset, i.e., the rotor offset evaluation value. Finally, the overall operating status of the PMSM is assessed. Based on the rotor offset evaluation values corresponding to all acquisition locations of the PMSM, real-time monitoring results of the PMSM's operating status are obtained. This addresses the problem of inaccurate monitoring of the PMSM's operating status due to environmental noise interference, thus improving the accuracy of PMSM operating status monitoring. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a flowchart illustrating a synchronous motor operation status monitoring method according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating the process of obtaining the probability of obtaining the main frequency according to an embodiment of the present invention. Detailed Implementation
[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] Please see Figure 1 The diagram illustrates a flowchart of a synchronous motor operation status monitoring method according to an embodiment of the present invention, which includes the following steps: Step S001: Collect vibration signals and power at all collection times within the preset time period at different preset positions of the permanent magnet synchronous motor for a preset time period.
[0019] Piezoelectric vibration sensors are installed on the bearings, stator end covers, and rotor shaft of the permanent magnet synchronous motor. The orientation of the piezoelectric vibration sensors is parallel to the installation angle to ensure sufficient capture of vibration signals at the installation locations. The vibration signals of the bearings are collected using piezoelectric vibration sensors.
[0020] Preferably, in one embodiment of this application, the sampling frequency of the vibration signal is 500Hz, and the vibration signal is collected within one minute. The sensitivity of the piezoelectric vibration sensor is 500mV / g to capture minute vibration changes. In practical applications, as other implementations, the implementer can determine the sampling frequency, sampling duration, and sensitivity of the piezoelectric vibration sensor according to the actual situation. This application does not impose any special limitations.
[0021] It is understandable that vibration signals acquired using piezoelectric vibration sensors exhibit a continuously changing curve in the time domain.
[0022] A current sensor and a voltage sensor are connected in the circuit of the permanent magnet synchronous motor. At each vibration signal acquisition moment, the current and voltage are collected by the current sensor and the voltage sensor respectively.
[0023] Calculate the power of the permanent magnet synchronous motor at the same acquisition time based on the current and voltage of the permanent magnet synchronous motor at the same acquisition time.
[0024] Calculating the power of a permanent magnet synchronous motor based on its current and voltage is a well-known technique and will not be elaborated further.
[0025] It should be noted that, for ease of calculation, all currents, voltages, and power involved in the calculations in this embodiment have undergone data preprocessing to eliminate the influence of dimensions. This embodiment uses the Z-Score standard normalization method to remove dimensions from currents, voltages, and power, mapping the values to the interval [0,1]. In practical applications, implementers can use other methods such as the existing maximum-minimum normalization method for dimension removal, which are not limited here.
[0026] Thus, the vibration signal of the permanent magnet synchronous motor within one minute and the power at all acquisition moments within one minute are obtained.
[0027] Step S002: Based on the vibration signal of the permanent magnet synchronous motor collected from the same preset location, the spectrum of the permanent magnet synchronous motor is obtained. Based on the distribution of all frequencies contained in the spectrum of the permanent magnet synchronous motor and the amplitude values corresponding to all frequencies, the probability of the dominant frequency of all frequencies contained in the spectrum of the permanent magnet synchronous motor is determined. Periodic characteristic frequencies are screened based on the probability of the dominant frequency. The operating status of the permanent magnet synchronous motor is initially screened based on the periodic characteristic frequencies. The numerical relationship between the amplitude corresponding to all periodic characteristic frequencies and the amplitude corresponding to all frequencies contained in the spectrum of the permanent magnet synchronous motor is compared. If the judgment result shows that the permanent magnet synchronous motor may have rotor offset or rotor instability, an adaptive filter is constructed based on the periodic characteristic frequencies to process the original vibration signal and obtain the denoised vibration signal of the permanent magnet synchronous motor.
[0028] During the operation of a permanent magnet synchronous motor, if the rotor of the permanent magnet synchronous motor is misaligned or unstable, due to the influence of gravity, the rotor will experience regular overload and weightlessness with each rotation. Therefore, the vibration signal of the permanent magnet synchronous motor affected by frequent periodic overload and weightlessness will also exhibit periodicity.
[0029] First, a Fourier transform is performed on the vibration signals collected from the same location of the permanent magnet synchronous motor (PMSM) to obtain the PSM's spectrum. The horizontal axis of the spectrum represents frequency, and the vertical axis represents the amplitude corresponding to each frequency. The larger the amplitude corresponding to a frequency, the greater the energy that frequency occupies in the vibration signal. Therefore, in the vibration signals collected from the same location of a PMSM exhibiting rotor misalignment or instability, there will be significantly larger amplitudes, and frequencies with larger amplitudes and stronger isolation correspond to rotor overload and weight loss information. In contrast, in the vibration signals of a normally operating PMSM, the amplitudes of each frequency are relatively close.
[0030] Based on the distribution of all frequencies in the spectrum of a permanent magnet synchronous motor and the amplitude values corresponding to all frequencies, the probability of a dominant frequency for any frequency in the spectrum of a permanent magnet synchronous motor is determined. Specifically, the method for determining the probability of a dominant frequency is as follows: The Z-scores of the amplitudes of all frequencies contained in the spectrum of the permanent magnet synchronous motor are obtained, and the Z-scores are mapped to the interval between 0 and 1 using the sigmoid function. The calculation of the Z-scores of all frequencies contained in the spectrum of the permanent magnet synchronous motor is a well-known technique and will not be elaborated further. It should be noted that this embodiment uses the Z-score standard normalization method to calculate the normalized value. In practical applications, implementers may use other existing methods such as the maximum-minimum normalization method or the sigmoid function to calculate the normalized value; this is not limited here.
[0031] When the Z fraction of all frequencies contained in the spectrum of a permanent magnet synchronous motor is larger, the frequency with a prominent amplitude proportion in the spectrum of the permanent magnet synchronous motor is more obvious, and the information of rotor offset or rotor instability contained in the vibration signal of the permanent magnet synchronous motor is more significant. At this time, the overweight and weight loss of the permanent magnet synchronous motor is more significant.
[0032] Let any frequency contained in the spectrum of the permanent magnet synchronous motor be denoted as the target frequency, and let the mean of the amplitudes corresponding to all frequencies contained in the spectrum of the permanent magnet synchronous motor be denoted as the frequency mean of the permanent magnet synchronous motor. Let the ratio of the amplitude corresponding to the target frequency to the frequency mean of the permanent magnet synchronous motor be denoted as the first ratio of the target frequency, and let the product of the first ratio of the target frequency and the significance of the overweight and weight loss of the permanent magnet synchronous motor be denoted as the dominant frequency probability of the target frequency.
[0033] When the amplitude corresponding to the target frequency is larger than the average frequency of the permanent magnet synchronous motor, and the overweight and weight loss of the permanent magnet synchronous motor are more significant, the target frequency is more likely to be the frequency with a prominent amplitude in the spectrum of the permanent magnet synchronous motor. The vibration signal of the permanent magnet synchronous motor contains more significant information about rotor offset or rotor instability. In this case, the target frequency is more likely to be the dominant frequency.
[0034] It is understandable that for each sampling location of a permanent magnet synchronous motor (PMSM), there is a corresponding PSM spectrum. The same method can be used to obtain the probability of a dominant frequency within any frequency in the PSM spectrum, that is, to obtain the probability of the dominant frequency of all frequencies within the spectrum corresponding to each sampling location of the PSM.
[0035] The flowchart for obtaining the probability of obtaining the main frequency is as follows: Figure 2 As shown.
[0036] When the probability of the dominant frequency is greater than or equal to the first threshold, the frequency corresponding to the probability of the dominant frequency is recorded as the periodic characteristic frequency. The sum of the amplitudes corresponding to all frequencies contained in the spectrum of the permanent magnet synchronous motor is recorded as the amplitude sum of the permanent magnet synchronous motor.
[0037] When the sum of the amplitudes corresponding to all periodic characteristic frequencies is less than the ratio of the sum of the amplitudes of the permanent magnet synchronous motor to the second threshold, it is determined that the permanent magnet synchronous motor has not experienced rotor offset or rotor instability during the acquisition time period corresponding to the vibration signal, and the permanent magnet synchronous motor is judged to be in good operating condition, and no further analysis is required.
[0038] When the ratio of the sum of the amplitudes corresponding to all periodic characteristic frequencies to the sum of the amplitudes of the permanent magnet synchronous motor is greater than or equal to the second threshold, it is determined that the permanent magnet synchronous motor has a rotor offset or rotor instability problem during the acquisition time period corresponding to the vibration signal, and further analysis is carried out based on the periodic characteristic frequencies. For cases initially determined to be abnormal, in order to further analyze its dynamic changes in the time domain, it is necessary to extract the main fault components. The specific method is as follows: the selected periodic characteristic frequencies are used as the center frequency or passband range of the bandpass filter, and the original vibration signal of the permanent magnet synchronous motor is bandpass filtered.
[0039] Understandably, when the judgment result corresponding to the partial acquisition position of the permanent magnet synchronous motor is "the permanent magnet synchronous motor is in good operating condition", the subsequent analysis of the partial acquisition position of the permanent magnet synchronous motor corresponding to the judgment result of "the permanent magnet synchronous motor is in good operating condition" will stop, and the analysis of the denoised vibration signal of the permanent magnet synchronous motor corresponding to the judgment result of "the permanent magnet synchronous motor has a problem of rotor offset or rotor instability during the acquisition time period corresponding to the vibration signal" will continue. Each acquisition position of the permanent magnet synchronous motor corresponds to a denoised vibration signal of the permanent magnet synchronous motor.
[0040] Wherein, the first threshold and the second threshold are both preset constant values. In this embodiment, the first threshold is set to 0.8 and the second threshold is set to 0.5.
[0041] The signal after the targeted filtering process described above is the denoised vibration signal of the permanent magnet synchronous motor. This signal removes irrelevant environmental noise and retains only the signal components that are highly correlated with the rotor's periodic faults, which are used for the fine quantitative evaluation based on the time interval sequence and power sequence in the subsequent step S003.
[0042] Thus, we obtain the judgment result that the permanent magnet synchronous motor is in good operating condition, or we obtain the noise-reduced vibration signal of the permanent magnet synchronous motor.
[0043] Step S003: Based on the time interval between the acquisition times corresponding to adjacent extreme points in the denoised vibration signal of the permanent magnet synchronous motor, obtain the time interval sequence of the permanent magnet synchronous motor; based on the power of the permanent magnet synchronous motor, obtain the power sequence of the permanent magnet synchronous motor; based on the difference between the time interval sequence and the power sequence of the permanent magnet synchronous motor, the changing trend of the values contained in the time interval sequence of the permanent magnet synchronous motor, and the changing trend of the values contained in the power sequence of the permanent magnet synchronous motor, determine the rotor offset evaluation value of the permanent magnet synchronous motor.
[0044] When rotor misalignment or instability occurs, the rotor will experience regular overload and weightlessness with each rotation. In this situation, if the current and voltage of the permanent magnet synchronous motor (PMSM) decrease, the PSM's operating speed will slow down, and the period of the noise-reducing vibration signal will become longer relative to the period of the main vibration signal. Conversely, if the current and voltage of the PSM increase, the PSM's operating speed will increase, and the period of the noise-reducing vibration signal will become shorter relative to the main vibration signal. Therefore, when rotor misalignment or instability occurs, the trends in the changes of the PSM's current and voltage are clearly synchronized with the trends in the changes of the vibration signal's period. Furthermore, the trends in the changes of the PSM's power are also clearly synchronized with the trends in the changes of the vibration signal's period.
[0045] Calculate the time interval between adjacent extreme points in the denoised vibration signal of the permanent magnet synchronous motor (PMSM). Arrange all time intervals according to the chronological order of the acquisition times of the extreme points corresponding to the time intervals to obtain the time interval sequence of the PMSM. Arrange all the power data of the PMSM collected within the acquisition time period corresponding to the vibration signal of the PMSM according to the chronological order of the acquisition times to obtain the original power sequence of the PMSM.
[0046] To eliminate the impact of differences in data dimensions and orders of magnitude on similarity calculations, both the original time interval sequence and the original power sequence are standardized. Specifically, the Z-Score standardization method is used to process the original time interval sequence to obtain a standard time interval sequence; the same method is used to process the original power sequence to obtain a standard power sequence.
[0047] The DTW distance between the standard time interval sequence and the standard power sequence of the permanent magnet synchronous motor (PMSM) is denoted as the sequence difference between the time interval sequence and the power sequence. The average absolute values of the slopes at corresponding points on the time interval curve and the power curve of the PMSM are denoted as the average slope of the time interval and the average slope of the power, respectively. The product of the average slope of the power and the average slope of the time interval is denoted as the fluctuation intensity factor of the PMSM. Considering that a smaller DTW distance indicates higher synchronization, a negative exponential function is used to map the sequence difference to a synchronization coefficient (e.g., using...). The product of the fluctuation intensity factor and the synchronization coefficient is denoted as the rotor offset evaluation value of the permanent magnet synchronous motor.
[0048] Considering that a smaller DTW distance represents higher synchronization, and that the synchronization is extremely high during rotor offset faults, a negative exponential function is used to map the difference value to a similarity value. The product of the similarity value and the synchronization coefficient is recorded as the rotor offset evaluation value of the permanent magnet synchronous motor.
[0049] When a rotor misalignment fault occurs in a motor, the changes in power and time interval are highly synchronized. DTW approaches 0, the synchronization coefficient approaches 1, and the drastic fluctuations in both values lead to an increase in the fluctuation intensity factor, resulting in a significant increase in the final evaluation value, which facilitates the monitoring of anomalies.
[0050] Among them, the polynomial fitting technique is a known technique for curve fitting of the time interval sequence and power sequence of the permanent magnet synchronous motor, and the DTW distance between the time interval sequence and power sequence of the permanent magnet synchronous motor is a known technique, which will not be elaborated further.
[0051] It is understandable that, apart from the permanent magnet synchronous motor sampling location corresponding to "permanent magnet synchronous motor operating in good condition", each permanent magnet synchronous motor sampling location corresponds to a noise-reduced vibration signal of the permanent magnet synchronous motor, and each permanent magnet synchronous motor sampling location also corresponds to a rotor offset evaluation value of the permanent magnet synchronous motor.
[0052] Thus, the rotor offset evaluation value of the permanent magnet synchronous motor is obtained.
[0053] Step S004: Based on the rotor offset evaluation values of the permanent magnet synchronous motor corresponding to all the acquisition positions of the permanent magnet synchronous motor, obtain the real-time monitoring results of the operating status of the permanent magnet synchronous motor.
[0054] Since each vibration signal acquisition position of the permanent magnet synchronous motor can only indicate the current working status of the permanent magnet synchronous motor, and is insufficient to measure the overall working status of the permanent magnet synchronous motor, the real-time monitoring results of the operating status of the permanent magnet synchronous motor are obtained based on the rotor offset evaluation value of the permanent magnet synchronous motor corresponding to all acquisition positions.
[0055] Considering that faults in permanent magnet synchronous motors may manifest as local anomalies, resulting in large differences in evaluation values at different locations, or as overall faults, where evaluation values at all locations are large but with small differences, a composite index including "overall severity" and "spatial dispersion" is constructed to avoid missed detections caused by using only dispersion.
[0056] The specific method is as follows: Calculate the arithmetic mean of the rotor offset evaluation values corresponding to all acquisition positions of the permanent magnet synchronous motor, and calculate the average absolute deviation of the rotor offset evaluation values corresponding to all acquisition positions of the permanent magnet synchronous motor. The sum of the arithmetic mean and the average absolute deviation is recorded as the rotor anomaly evaluation value of the permanent magnet synchronous motor.
[0057] When the rotor abnormality evaluation value of the permanent magnet synchronous motor is greater than or equal to the third threshold, the permanent magnet synchronous motor is judged to be operating abnormally; when the rotor abnormality evaluation value of the permanent magnet synchronous motor is less than the third threshold, the permanent magnet synchronous motor is judged to be operating normally.
[0058] The third value is a preset constant value. In this embodiment, the first threshold value is 0.9.
[0059] At this point, the real-time monitoring results of the permanent magnet synchronous motor's operating status are obtained.
[0060] Based on the same inventive concept as the above method, this embodiment of the invention also provides a synchronous motor operating status monitoring device, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described synchronous motor operating status monitoring methods.
[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for monitoring the operating status of a synchronous motor, characterized in that, The method includes the following steps: Vibration signals and power at all sampling times within a preset time period are collected at different preset positions of the permanent magnet synchronous motor. Based on the vibration signal of the permanent magnet synchronous motor collected from the same preset location, the spectrum of the permanent magnet synchronous motor is obtained. Based on the distribution of all frequencies contained in the spectrum of the permanent magnet synchronous motor and the amplitude values corresponding to all frequencies, the probability of the dominant frequency of all frequencies contained in the spectrum is determined, and periodic characteristic frequencies are screened. The operating status of the permanent magnet synchronous motor is initially screened using the periodic characteristic frequencies. When the screening result is abnormal, the vibration signal is filtered based on the periodic characteristic frequencies to obtain a denoised vibration signal. The time interval sequence of the permanent magnet synchronous motor is obtained based on the denoised vibration signal, and the power sequence of the permanent magnet synchronous motor is obtained based on the power. The time interval sequence and the power sequence are then standardized. Based on the dynamic time warping (DTW) distance between the standardized time interval sequence and the power sequence, and the changing trends of the two, the rotor offset evaluation value of the permanent magnet synchronous motor is determined. Based on the rotor offset evaluation values of the permanent magnet synchronous motor corresponding to all the acquisition positions of the permanent magnet synchronous motor, the real-time monitoring results of the operating status of the permanent magnet synchronous motor are obtained. The method for determining the probability of the dominant frequency of all frequencies in the spectrum of a permanent magnet synchronous motor based on the distribution of all frequencies and the amplitude values corresponding to all frequencies is as follows: The normalized Z-score of all frequencies contained in the spectrum of a permanent magnet synchronous motor is denoted as the significance of overweight and weight loss of the permanent magnet synchronous motor. Let any frequency contained in the spectrum of the permanent magnet synchronous motor be denoted as the target frequency, and let the mean of the amplitudes corresponding to all frequencies contained in the spectrum of the permanent magnet synchronous motor be denoted as the frequency mean of the permanent magnet synchronous motor; let the ratio of the amplitude corresponding to the target frequency to the frequency mean of the permanent magnet synchronous motor be denoted as the first ratio of the target frequency. The probability of the target frequency as the main frequency is determined based on the first ratio of the target frequency and the significance of the overweight and weight loss of the permanent magnet synchronous motor. The method for determining the likelihood of the target frequency's dominant frequency based on the first ratio of the target frequency and the significance of the overweight and weight loss of the permanent magnet synchronous motor includes the following specific methods: The product of the first ratio of the target frequency and the significance of the overweight and weight loss of the permanent magnet synchronous motor is denoted as the probability of the main frequency of the target frequency.
2. The method for monitoring the operating status of a synchronous motor according to claim 1, characterized in that, The specific methods for filtering cyclical characteristic frequencies based on the probability of dominant frequency are as follows: When the probability of the main frequency is greater than or equal to the preset first threshold, the frequency corresponding to the probability of the main frequency is recorded as the periodic characteristic frequency.
3. The method for monitoring the operating status of a synchronous motor according to claim 1, characterized in that, The specific methods for performing preliminary screening of the operating status of the permanent magnet synchronous motor using the periodic characteristic frequency and for obtaining denoised vibration signals are as follows: When the sum of the amplitudes corresponding to all periodic characteristic frequencies is less than the ratio of the sum of the amplitudes of the permanent magnet synchronous motor to the preset second threshold, it is determined that the permanent magnet synchronous motor has not experienced rotor offset or rotor instability during the acquisition time period corresponding to the vibration signal, and the permanent magnet synchronous motor is determined to be in good operating condition. When the sum of the amplitudes corresponding to all periodic characteristic frequencies is greater than or equal to the sum of the amplitudes of the permanent magnet synchronous motor, the preliminary screening result is determined to be abnormal. To address the abnormal results, the periodic characteristic frequency is used as a parameter of a bandpass filter to perform bandpass filtering on the vibration signal of the permanent magnet synchronous motor, thereby obtaining a denoised vibration signal.
4. The method for monitoring the operating status of a synchronous motor according to claim 1, characterized in that, The time interval sequence and the power sequence are standardized, specifically as follows: Calculate the time interval between the acquisition times corresponding to adjacent extreme points in the denoised vibration signal, and arrange them in the order of acquisition times to obtain the original time interval sequence; arrange the power corresponding to the acquisition times in order to obtain the original power sequence; process the original time interval sequence and the original power sequence using the Z-Score normalization method to obtain the normalized time interval sequence and power sequence.
5. The method for monitoring the operating status of a synchronous motor according to claim 1, characterized in that, The determination of the rotor offset evaluation value of the permanent magnet synchronous motor based on the dynamic time warping (DTW) distance between the standardized time interval sequence and the power sequence, and the changing trends of both, includes: The DTW distance between the standardized time interval sequence and the power sequence is calculated, and the DTW distance is mapped to a synchronization coefficient using a negative exponential function. Curve fitting is performed on the standardized time interval sequence and the power sequence respectively to obtain the average slope of the time interval and the average slope of the power. The product of the average slope of the power and the average slope of the time interval is denoted as the fluctuation intensity factor of the permanent magnet synchronous motor.
6. The method for monitoring the operating status of a synchronous motor according to claim 5, characterized in that, The specific method for determining the rotor offset evaluation value of the permanent magnet synchronous motor is as follows: The product of the fluctuation intensity factor and the synchronization coefficient is denoted as the rotor offset evaluation value of the permanent magnet synchronous motor.
7. The method for monitoring the operating status of a synchronous motor according to claim 1, characterized in that, The method for obtaining real-time monitoring results of the permanent magnet synchronous motor's operating status based on the rotor offset evaluation values of the permanent magnet synchronous motor corresponding to all acquisition positions includes the following: Calculate the arithmetic mean of the rotor offset evaluation values corresponding to all data collection positions of the permanent magnet synchronous motor, and denote it as the overall severity. The average absolute deviation of the rotor offset evaluation values corresponding to all acquisition positions of the permanent magnet synchronous motor is calculated and denoted as the spatial dispersion. The sum of the overall severity and the spatial dispersion is denoted as the rotor anomaly evaluation value of the permanent magnet synchronous motor. When the rotor abnormality evaluation value of the permanent magnet synchronous motor is greater than or equal to the preset third threshold, the permanent magnet synchronous motor is judged to be operating abnormally. When the rotor abnormality evaluation value of the permanent magnet synchronous motor is less than the preset third threshold, the permanent magnet synchronous motor is judged to be operating normally.
8. A synchronous motor operating status monitoring device, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as claimed in any one of claims 1-7.