Method and device for measuring rotating speed or rotor frequency of motor based on three-axis magnetometer

Abstract

The invention discloses a motor rotating speed or rotor frequency measuring method and device based on a three-axis magnetometer, and the method comprises the steps: obtaining a magnetic flux signal based on the three-axis magnetometer when a motor rotates, the three-axis magnetometer is arranged adjacent to the motor and is not in contact with the motor; respectively obtaining a power frequency magnetic field signal and a slip magnetic field signal in low-frequency distribution according to the magnetic flux signal and a predetermined high-pass filter and a predetermined low-pass filter; according to the obtained power supply frequency magnetic field signal and the slip magnetic field signal, analyzing to obtain the stator current frequency and the slip ratio of the motor; and according to the obtained stator current frequency and the slip ratio, calculating to obtain a motor rotating speed or a rotor frequency.

Description

Technical Field

[0001] The present invention relates to the field of computer technology, and in particular to a method and device for measuring motor speed or rotor frequency based on a three-axis magnetometer. Background Art

[0002] In chemical applications, motors and pumps are essential equipment, and their operating status directly affects the efficiency and safety of the entire chemical process. Therefore, it is very important to monitor the use status of the motor.

[0003] There are two main methods for traditional motor speed measurement: contact and non-contact. The contact speed measurement method mainly converts the motor speed information into an electrical signal for measurement through mechanical means, such as a tachometer generator, photoelectric encoder, etc. The non-contact speed measurement method mainly uses electromagnetic induction, ultrasound, laser and other principles to achieve non-contact measurement of the motor speed. However, the application effect of these methods in complex environments such as chemical industry is not ideal.

[0004] Solutions of related technologies: Existing motor speed measurement technologies mainly rely on mechanical methods or principles such as electromagnetic induction, ultrasound, laser, etc. Although these methods can measure the motor speed, they may be affected by various interference factors in a complex environment such as chemical industry, resulting in inaccurate measurement results.

[0005] In addition, the existing motor speed measurement technology has the following major problems in chemical applications: First, due to the complexity of the chemical environment, traditional speed measurement methods may be affected by various interference factors, resulting in inaccurate measurement results. Second, existing speed measurement methods often require direct contact with the motor, which is unrealistic in some cases, for example, when the motor is rotating at high speed, or the environment where the motor is located is very harsh and direct contact measurement is not possible. Finally, existing speed measurement methods usually require complex signal processing and calculations, which is a challenge for real-time monitoring of the motor's status.

[0006] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0007] The main purpose of the present invention is to provide a method and device for measuring the motor speed or rotor frequency based on a three-axis magnetometer, aiming to solve or partially solve the above-mentioned problems in the prior art.

[0008] To achieve the above object, the present invention provides a method for measuring motor speed or rotor frequency based on a three-axis magnetometer, which is characterized by comprising:

[0009] Acquiring a magnetic flux signal when the motor rotates based on a three-axis magnetometer, wherein the three-axis magnetometer is arranged adjacent to the motor and does not contact the motor;

[0010] According to the magnetic flux signal and a predetermined high-pass filter and low-pass filter, a power frequency magnetic field signal of high-frequency distribution and a slip magnetic field signal of low-frequency distribution are obtained respectively;

[0011] According to the obtained power frequency magnetic field signal and slip magnetic field signal, the stator current frequency and slip rate of the motor are analyzed and obtained;

[0012] The motor speed or rotor frequency is calculated based on the obtained stator current frequency and the slip rate.

[0013] Preferably, in the method for measuring the motor speed or rotor frequency based on a three-axis magnetometer, the step of calculating the motor speed or rotor frequency according to the obtained stator current frequency and the slip rate comprises:

[0014] According to the obtained stator current frequency and the slip rate, the motor rotor frequency is calculated, and the calculation formula is as follows:

[0015] f2 = s * f1;

[0016] According to the motor rotor frequency and stator current frequency, the motor speed is calculated. The calculation formula is as follows:

[0017] or,

[0018]

[0019] Where, f1 is the stator current frequency;

[0020] f2 is the motor rotor frequency;

[0021] s is the slip rate;

[0022] P is the number of pole pairs of the motor;

[0023] T1 is the stator current variation period, T1 = 1 / f1;

[0024] T2 is the rotor current variation period, T2 = 1 / f2;

[0025] n0 is the synchronous speed of the motor;

[0026] n is the motor speed.

[0027] Preferably, in the method for measuring the motor speed or rotor frequency based on the three-axis magnetometer, the analysis of the obtained power frequency magnetic field signal and the slip magnetic field signal to obtain the stator current frequency and the slip rate of the motor includes:

[0028] According to the obtained power frequency magnetic field signal and slip magnetic field signal, the following formulas are used for decomposition, and the maximum eigenvalue direction is selected for data dimension reduction to obtain a one-dimensional high-frequency magnetic flux signal and a one-dimensional low-frequency magnetic flux signal, respectively. The formulas are as follows:

[0029] A=USV t ;

[0030] Using a pre-established regression model, respectively determining the distribution information of the signal power in the frequency domain for the one-dimensional high-frequency magnetic flux signal and the one-dimensional low-frequency magnetic flux signal;

[0031] The peak frequency output is extracted from the obtained signal power distribution information in the frequency domain to obtain the stator current frequency and slip rate;

[0032] Among them, U and V are orthogonal matrices, and are the singular vectors of A;

[0033] S is the singular value of A.

[0034] Preferably, in the method for measuring the motor speed or rotor frequency based on the three-axis magnetometer, before the step of using a pre-established regression model to determine the distribution information of the signal power in the frequency domain for the one-dimensional high-frequency magnetic flux signal and the one-dimensional low-frequency magnetic flux signal, the testing method further includes:

[0035] Establish a regression model, the regression model is as follows:

[0036] x(n)=∑(a i *x(ni))+e(n);

[0037] Among them, a i is the autoregression coefficient;

[0038] e(n) is the noise term;

[0039] x(n) is the signal sequence.

[0040] Preferably, in the motor speed or rotor frequency measurement method based on the three-axis magnetometer, the pre-established regression model is used to determine the distribution information of the signal power in the frequency domain for the one-dimensional high-frequency magnetic flux signal and the one-dimensional low-frequency magnetic flux signal, respectively, including:

[0041]

[0042] Among them, σ 2 is the noise variance;

[0043] j is the imaginary unit;

[0044] ω is the angular frequency;

[0045] P(ω) is the distribution information of signal power in the frequency domain.

[0046] Preferably, in the motor speed or rotor frequency measurement method based on the three-axis magnetometer, the peak frequency output is extracted from the obtained signal power distribution information in the frequency domain to obtain the stator current frequency and the slip rate, including:

[0047] According to the peak finding function findpeaks(), the peak frequency output is extracted from the distribution information of the signal power in the frequency domain to obtain the stator current frequency and the slip rate.

[0048] Preferably, in the method for measuring the motor speed or rotor frequency based on a three-axis magnetometer, the three-axis magnetometer is arranged adjacent to the motor and the distance from the motor is 9 cm-11 cm.

[0049] In order to achieve the above object, the present invention further provides a device for measuring the motor speed or rotor frequency based on a three-axis magnetometer, and the device for measuring the motor speed or rotor frequency based on a three-axis magnetometer comprises:

[0050] an acquisition unit, configured to acquire a magnetic flux signal when the motor rotates based on a three-axis magnetometer, wherein the three-axis magnetometer is disposed adjacent to the motor and does not contact the motor;

[0051] A filtering unit, used to obtain a power frequency magnetic field signal and a slip magnetic field signal of low frequency distribution according to the magnetic flux signal and a predetermined high-pass filter and low-pass filter respectively;

[0052] An analysis unit, used for analyzing and obtaining the stator current frequency and slip rate of the motor according to the obtained power frequency magnetic field signal and slip magnetic field signal;

[0053] The calculation unit is used to calculate the motor speed or rotor frequency according to the obtained stator current frequency and the slip rate.

[0054] In order to achieve the above object, the present invention further provides a computer device, characterized in that it includes:

[0055] at least one processor; and,

[0056] a memory communicatively connected to the at least one processor; wherein,

[0057] The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the above-mentioned method for measuring the motor speed or rotor frequency based on the three-axis magnetometer.

[0058] In order to achieve the above object, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-mentioned method for measuring the motor speed or rotor frequency based on a three-axis magnetometer.

[0059] The present invention has at least the following beneficial effects:

[0060] The present invention obtains a magnetic flux signal when a motor rotates based on a three-axis magnetometer, and the three-axis magnetometer is arranged adjacent to the motor and does not contact the motor; a power supply frequency magnetic field signal and a slip magnetic field signal of low frequency distribution are obtained respectively according to the magnetic flux signal and a predetermined high-pass filter and a low-pass filter; the stator current frequency and the slip rate of the motor are analyzed according to the obtained power supply frequency magnetic field signal and the slip magnetic field signal; the motor speed or rotor frequency is calculated according to the obtained stator current frequency and the slip rate, so that the motor speed or rotor frequency can be accurately calculated without contacting the motor.

[0061] Furthermore, the method of calculating the motor speed or rotor frequency by the present invention can be widely used in the fields of motor operation status monitoring, chemical production efficiency optimization, motor equipment failure prevention and diagnosis, etc. By detecting the change of magnetic flux when the motor rotates through a three-axis magnetometer, non-contact measurement of the motor frequency and speed can be achieved, avoiding the problem that the traditional speed measurement method needs to be in direct contact with the motor, and improving the safety and reliability of the measurement.

[0062] Furthermore, the method provided by the present invention can realize accurate measurement of motor speed in complex environments, which helps to improve the efficiency and safety of chemical production.

[0063] Furthermore, the signal processing and calculation in the method provided by the present invention are relatively simple, which is conducive to the real-time monitoring of the motor status and helps to prevent and diagnose the faults of the motor equipment.

[0064] Furthermore, a 3D linear magnetometer is used to detect changes in magnetic flux when the motor rotates: by installing a three-axis magnetometer near the motor and using its sensitivity to the magnetic field, the changes in magnetic flux generated when the motor rotates can be detected in real time. This non-contact measurement method can effectively avoid measurement errors caused by factors such as motor vibration and temperature changes in traditional contact measurement methods, and improve measurement accuracy. Non-contact measurement of motor frequency and speed avoids the problem that traditional speed measurement methods require direct contact with the motor, especially when the motor is rotating at high speed or in a harsh environment, the advantages of non-contact measurement are more obvious.

[0065] Furthermore, the motor frequency and speed calculation based on the magnetic flux change: by analyzing the magnetic flux change signal detected by the three-axis magnetometer, the motor frequency and speed information contained therein are extracted. Compared with the traditional complex calculation method, this signal processing method is simpler and faster, and can meet the needs of real-time monitoring of the motor status.

[0066] Furthermore, considering the complex electromagnetic environment in chemical application scenarios, which may interfere with motor speed measurement, this technical solution adopts a variety of anti-interference designs, such as signal filtering, noise elimination and other technologies to ensure the stability and reliability of motor speed measurement.

[0067] Furthermore, compared with the traditional speed measurement method, the magnetometer speed measurement method has a stronger anti-interference ability. In the complex environment of chemical industry, various interference factors may affect the accuracy of the speed measurement results, while the magnetometer speed measurement method can effectively resist these interferences and ensure the accuracy of the measurement results.

[0068] Furthermore, the method provided by the present invention can directly obtain the motor's rotational frequency and speed by detecting the change in magnetic flux when the motor rotates, without the need for complex signal processing and calculation, which greatly simplifies the signal processing process and is conducive to the real-time monitoring of the motor status.

[0069] Furthermore, the method provided by the present invention is not only applicable to ordinary motors, but also to motors in special environments, such as high temperature, high pressure, strong corrosion and the like, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a flow chart of a first embodiment of a method for measuring a motor speed or rotor frequency based on a three-axis magnetometer provided by the present invention;

[0071] Figure 2 A schematic flow chart of a second embodiment of a method for measuring a motor speed or rotor frequency based on a three-axis magnetometer provided by the present invention;

[0072] Figure 3 A schematic diagram of a first embodiment of a device for measuring motor speed or rotor frequency based on a three-axis magnetometer provided by the present invention;

[0073] Figure 4 FIG. 1 is a schematic diagram of a computer device according to a first embodiment of the present invention.

[0074] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0075] In the embodiments of the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0076] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0077] In the embodiments of the present invention, the term "plurality" refers to two or more than two, and other quantifiers are similar.

[0078] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. However, it can be understood by those skilled in the art that in the embodiments of the present invention, many technical details are proposed in order to enable the reader to better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present invention can also be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0079] In order to solve the above problems, the present embodiment relates to a method for measuring motor speed or rotor frequency based on a three-axis magnetometer, which can be applied to computer equipment, or electronic devices with data processing capabilities such as desktops, tablets, notebooks, etc., without specific restrictions.

[0080] The implementation details of the positioning method according to the first embodiment of the present invention are described below. The following content is only the implementation details provided for the convenience of understanding and is not necessary for implementing this solution.

[0081] The specific process of this implementation is as follows: Figure 1 As shown, specifically including:

[0082] Step S100, obtaining a magnetic flux signal when the motor rotates based on a three-axis magnetometer, wherein the three-axis magnetometer is arranged adjacent to the motor and does not contact the motor;

[0083] It should be understood that the three-axis magnetometer is installed near the motor and uses its sensitivity to the magnetic field to detect the change in magnetic flux generated when the motor rotates in real time, so that relevant data of the motor can be obtained through non-contact measurement. The selection of a three-axis magnetometer usually requires the selection of accuracy requirements.

[0084] In this embodiment, the selected 3D linear magnetometer model is MLX90393, which has the advantages of large range, high sensitivity, low power consumption, small size, etc., and is suitable for use in chemical application scenarios. Specifically, the magnetic flux change signal detected by the magnetometer is obtained in real time through the SPI interface of the 3D linear magnetometer.

[0085] The three-axis magnetometer needs to be installed near the motor. If the three-axis magnetometer is installed too far away, it will affect the measurement accuracy. If the three-axis magnetometer is installed too close, it may easily contact the motor and affect the operation of the motor. Therefore, in this embodiment, the distance between the three-axis magnetometer and the motor is about 10 cm, usually set to 9 cm-11 cm, so as to ensure that the three-axis magnetometer can accurately detect the change in magnetic flux generated when the motor rotates.

[0086] Usually, the working parameters of the three-axis magnetometer include: the sampling frequency is set to 200Hz-220Hz, and the filter parameter is set to 50Hz-60Hz to ensure the accuracy of the acquisition and processing of the magnetic flux change signal. The three-axis magnetometer detects the magnetic flux change when the motor rotates, and analyzes the detected magnetic flux change signal to extract the motor speed or rotor frequency of the motor.

[0087] In addition, since the motor magnetic field varies greatly in different positions and directions, there is often a problem of large differences in the data collected at different positions. A three-axis magnetometer can be used to collect magnetic field data in any direction at different positions. This method can be used to avoid problems caused by direction errors.

[0088] Step S200, obtaining a power frequency magnetic field signal and a slip magnetic field signal of low frequency distribution respectively according to the magnetic flux signal and a predetermined high-pass filter and low-pass filter;

[0089] It should be noted that when three-phase alternating current is applied to the stator of an asynchronous motor, a rotating magnetic field is naturally induced inside the motor, which is a composite of the basic rotating magnetic field components and the harmonic rotating magnetic field components. Among them, the magnetic flux caused by the basic rotating magnetic field crosses the air gap and interlinks with the stator and rotor windings at the same time, which is called the main magnetic flux. However, due to non-ideal factors in the structure of the asynchronous motor, such as uneven air gap, non-concentricity between the rotor and the shaft, etc., a part of the magnetic flux will deviate and only flow through the air gap and the rotor surface, but not associated with the rotor winding. This part is called stator leakage flux, especially the end leakage flux, whose frequency of change is consistent with the current frequency of the stator power supply. In addition, the speed difference between the stator and the rotor causes the rotor to continuously induce current and further generate its own rotating magnetic field. In this magnetic field, there will also be slot leakage flux, harmonic leakage flux and end leakage flux. In particular, the end leakage flux fluctuates with the frequency of the rotor current, although this part of the leakage flux is usually relatively small. Therefore, in order to adapt to the adaptive speed acquisition at different installation positions of the motor, a three-axis magnetometer is used to obtain the motor leakage magnetic field change signal, and the stator and rotor current change signals are extracted through signal processing to extract the motor speed.

[0090] It should be understood that the selection of high-pass filter and low-pass filter is to determine the filter bandwidth range of the filter according to different motors. To separate the power frequency magnetic field signal that occupies the main component of the magnetic field signal and the slip magnetic field signal distributed at a low frequency, the low-pass filter that needs to be set is slightly higher than the maximum slip of the motor * the number of stages P.

[0091] Since the slip rate range of common three-phase asynchronous motors usually does not exceed 2HZ, the low-pass filter range is set to: 0-4HZ, and the high-pass filter range is: 4HZ-analysis frequency. In this way, the three-axis magnetic flux signal is filtered by the high-pass filter and the low-pass filter respectively.

[0092] When the magnetic signal passes through a high-pass filter, a power frequency magnetic field signal is obtained. When the magnetic signal passes through a low-pass filter, a slip magnetic field signal with low frequency distribution can be obtained.

[0093] Step S300, analyzing and obtaining the stator current frequency and slip rate of the motor according to the obtained power frequency magnetic field signal and slip magnetic field signal;

[0094] Step S400, calculating the motor speed or rotor frequency according to the obtained stator current frequency and the slip rate.

[0095] Specifically, the step S400 includes:

[0096] According to the obtained stator current frequency and the slip rate, the motor rotor frequency is calculated, and the calculation formula is as follows:

[0097] f2 = s * f1;

[0098] According to the motor rotor frequency and stator current frequency, the motor speed is calculated. The calculation formula is as follows:

[0099] or,

[0100]

[0101] Where, f1 is the stator current frequency;

[0102] f2 is the motor rotor frequency;

[0103] s is the slip rate;

[0104] P is the number of pole pairs of the motor;

[0105] T1 is the stator current variation period, T1 = 1 / f1;

[0106] T2 is the rotor current variation period, T2 = 1 / f2;

[0107] n0 is the synchronous speed of the motor;

[0108] n is the motor speed.

[0109] The present invention obtains a magnetic flux signal when a motor rotates based on a three-axis magnetometer, and the three-axis magnetometer is arranged adjacent to the motor and does not contact the motor; a power supply frequency magnetic field signal and a slip magnetic field signal of low frequency distribution are obtained respectively according to the magnetic flux signal and a predetermined high-pass filter and a low-pass filter; the stator current frequency and the slip rate of the motor are analyzed according to the obtained power supply frequency magnetic field signal and the slip magnetic field signal; the motor speed or rotor frequency is calculated according to the obtained stator current frequency and the slip rate, so that the motor speed or rotor frequency can be accurately calculated without contacting the motor.

[0110] Figure 2 The second embodiment of the method for measuring the motor speed or rotor frequency based on the three-axis magnetometer provided by the present invention is shown. Figure 2 As shown, the step S300 includes:

[0111] Step S310: Decompose the obtained power frequency magnetic field signal and slip magnetic field signal using the following formulas respectively, and select the maximum eigenvalue direction to perform data dimension reduction, and obtain a one-dimensional high-frequency magnetic flux signal and a one-dimensional low-frequency magnetic flux signal respectively. The formulas are as follows:

[0112] A=USV t ;

[0113] Among them, U and V are orthogonal matrices, and are the singular vectors of A;

[0114] S is the singular value of A.

[0115] By using this formula to reduce the dimension, decompose and reconstruct the data, the main distribution of the magnetic field in space can be solved and the noise can be filtered out.

[0116] Step S320, using a pre-established regression model to determine the distribution information of signal power in the frequency domain for the one-dimensional high-frequency magnetic flux signal and the one-dimensional low-frequency magnetic flux signal respectively;

[0117] Establish a regression model, the regression model is as follows:

[0118] x(n)=Σ(a i *x(ni))+e(n);

[0119] Among them, a i is the autoregression coefficient;

[0120] e(n) is the noise term;

[0121] x(n) is the signal sequence.

[0122] Establish a regression model, the regression model is as follows:

[0123] x(n)=∑(a i *x(ni))+e(n);

[0124] Among them, a i is the autoregression coefficient;

[0125] e(n) is the noise term;

[0126] x(n) is the signal sequence.

[0127] Furthermore, the model for determining the distribution information of signal power in the frequency domain is as follows:

[0128]

[0129] Among them, σ 2 is the noise variance;

[0130] j is the imaginary unit;

[0131] ω is the angular frequency;

[0132] P(ω) is the distribution information of signal power in the frequency domain.

[0133] Step S330, extract the peak frequency output of the obtained signal power distribution information in the frequency domain to obtain the stator current frequency and slip rate.

[0134] It should be understood that a conventional peak finding method may be used, such as using the findpeaks() function.

[0135] In order to achieve the above object, the present invention also provides a device for measuring the motor speed or rotor frequency based on a three-axis magnetometer, such as Figure 3 As shown, the device for measuring the motor speed or rotor frequency based on a three-axis magnetometer includes an acquisition unit 510 , a filtering unit 520 , an analysis unit 530 , and a calculation unit 540 .

[0136] The acquisition unit 510 is used to acquire the magnetic flux signal when the motor rotates based on the three-axis magnetometer, and the three-axis magnetometer is arranged near the motor and does not contact the motor.

[0137] It should be understood that the three-axis magnetometer is installed near the motor and uses its sensitivity to the magnetic field to detect the change in magnetic flux generated when the motor rotates in real time, so that relevant data of the motor can be obtained through non-contact measurement. The selection of a three-axis magnetometer usually requires the selection of accuracy requirements.

[0138] In this embodiment, the selected 3D linear magnetometer model is MLX90393, which has the advantages of large range, high sensitivity, low power consumption, small size, etc., and is suitable for use in chemical application scenarios. Specifically, the magnetic flux change signal detected by the magnetometer is obtained in real time through the SPI interface of the 3D linear magnetometer.

[0139] The three-axis magnetometer needs to be installed near the motor. If the three-axis magnetometer is installed too far away, it will affect the measurement accuracy. If the three-axis magnetometer is installed too close, it may easily contact the motor and affect the operation of the motor. Therefore, in this embodiment, the distance between the three-axis magnetometer and the motor is about 10 cm, usually set to 9 cm-11 cm, so as to ensure that the three-axis magnetometer can accurately detect the change in magnetic flux generated when the motor rotates.

[0140] Usually, the working parameters of the three-axis magnetometer include: the sampling frequency is set to 200Hz-220Hz, and the filter parameter is set to 50Hz-60Hz to ensure the accuracy of the acquisition and processing of the magnetic flux change signal. The three-axis magnetometer detects the magnetic flux change when the motor rotates, and analyzes the detected magnetic flux change signal to extract the motor speed or rotor frequency of the motor.

[0141] In addition, since the motor magnetic field varies greatly in different positions and directions, there is often a problem of large differences in the data collected at different positions. A three-axis magnetometer can be used to collect magnetic field data in any direction at different positions. This method can be used to avoid problems caused by direction errors.

[0142] The filtering unit 520 is used to obtain a power frequency magnetic field signal and a slip magnetic field signal of low frequency distribution according to the magnetic flux signal and a predetermined high-pass filter and low-pass filter.

[0143] It should be noted that when three-phase alternating current is applied to the stator of an asynchronous motor, a rotating magnetic field is naturally induced inside the motor, which is a composite of the basic rotating magnetic field components and the harmonic rotating magnetic field components. Among them, the magnetic flux caused by the basic rotating magnetic field crosses the air gap and interlinks with the stator and rotor windings at the same time, which is called the main magnetic flux. However, due to non-ideal factors in the structure of the asynchronous motor, such as uneven air gap, non-concentricity between the rotor and the shaft, etc., a part of the magnetic flux will deviate and only flow through the air gap and the rotor surface, but not associated with the rotor winding. This part is called stator leakage flux, especially the end leakage flux, whose frequency of change is consistent with the current frequency of the stator power supply. In addition, the speed difference between the stator and the rotor causes the rotor to continuously induce current and further generate its own rotating magnetic field. In this magnetic field, there will also be slot leakage flux, harmonic leakage flux and end leakage flux. In particular, the end leakage flux fluctuates with the frequency of the rotor current, although this part of the leakage flux is usually relatively small. Therefore, in order to adapt to the adaptive speed acquisition at different installation positions of the motor, a three-axis magnetometer is used to obtain the motor leakage magnetic field change signal, and the stator and rotor current change signals are extracted through signal processing to extract the motor speed.

[0144] It should be understood that the selection of high-pass filter and low-pass filter is to determine the filter bandwidth range of the filter according to different motors. To separate the power frequency magnetic field signal that occupies the main component of the magnetic field signal and the slip magnetic field signal distributed at a low frequency, the low-pass filter that needs to be set is slightly higher than the maximum slip of the motor * the number of stages P.

[0145] Since the slip rate range of common three-phase asynchronous motors usually does not exceed 2HZ, the low-pass filter range is set to: 0-4HZ, and the high-pass filter range is: 4HZ-analysis frequency. In this way, the three-axis magnetic flux signal is filtered by the high-pass filter and the low-pass filter respectively.

[0146] When the magnetic signal passes through a high-pass filter, a power frequency magnetic field signal is obtained. When the magnetic signal passes through a low-pass filter, a slip magnetic field signal with low frequency distribution can be obtained.

[0147] The analysis unit 530 is used to analyze and obtain the stator current frequency and slip rate of the motor according to the obtained power frequency magnetic field signal and the slip magnetic field signal.

[0148] The calculation unit 540 is used to calculate the motor speed or rotor frequency according to the obtained stator current frequency and the slip rate.

[0149] Specifically, the calculation unit 540 is further used for:

[0150] According to the obtained stator current frequency and the slip rate, the motor rotor frequency is calculated, and the calculation formula is as follows:

[0151] f2 = s * f1;

[0152] According to the motor rotor frequency and stator current frequency, the motor speed is calculated. The calculation formula is as follows:

[0153] or,

[0154]

[0155] Where, f1 is the stator current frequency;

[0156] f2 is the motor rotor frequency;

[0157] s is the slip rate;

[0158] P is the number of pole pairs of the motor;

[0159] T1 is the stator current variation period, T1 = 1 / f1;

[0160] T2 is the rotor current variation period, T2 = 1 / f2;

[0161] n0 is the synchronous speed of the motor;

[0162] n is the motor speed.

[0163] In order to achieve the above object, the present invention also provides a computer device, such as Figure 4 As shown, the cleaning base station includes at least one processor 601; and a memory 602 that is communicatively connected to the at least one processor 601; wherein the memory 602 stores instructions that can be executed by the at least one processor 601, and the instructions are executed by the at least one processor 601 so that the at least one processor 601 can execute the above-mentioned method for measuring the motor speed or rotor frequency based on the three-axis magnetometer.

[0164] The memory 602 and the processor 601 are connected in a bus manner, and the bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors 601 and the memory 602 together. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices on a transmission medium. The data processed by the processor 601 is transmitted on a wireless medium via an antenna, and further, the antenna also receives data and transmits the data to the processor 601.

[0165] The processor 601 is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management and other control functions. The memory 602 can be used to store data used by the processor 601 when performing operations.

[0166] In order to achieve the above object, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above method for measuring the motor speed or rotor frequency based on a three-axis magnetometer.

[0167] That is, those skilled in the art can understand that all or part of the steps in the above-mentioned implementation method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor to execute all or part of the steps of the method described in each implementation of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0168] Obviously, the above described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, ordinary technicians in this field can make other different forms of changes or modifications without making creative work, which should all fall within the scope of protection of the present invention.

Claims

1. A method for measuring motor speed or rotor frequency based on a three-axis magnetometer, characterized in that: include: Acquiring a magnetic flux signal when the motor rotates based on a three-axis magnetometer, wherein the three-axis magnetometer is arranged adjacent to the motor and does not contact the motor; According to the magnetic flux signal and a predetermined high-pass filter and low-pass filter, a power frequency magnetic field signal of high-frequency distribution and a slip magnetic field signal of low-frequency distribution are obtained respectively; According to the obtained power frequency magnetic field signal and slip magnetic field signal, the stator current frequency and slip rate of the motor are analyzed and obtained; The motor speed or rotor frequency is calculated based on the obtained stator current frequency and the slip rate.

2. The method for measuring motor speed or rotor frequency based on a three-axis magnetometer according to claim 1, characterized in that: The step of calculating the motor speed or rotor frequency according to the obtained stator current frequency and the slip rate comprises: According to the obtained stator current frequency and the slip rate, the motor rotor frequency is calculated, and the calculation formula is as follows: f**f According to the motor rotor frequency and stator current frequency, the motor speed is calculated. The calculation formula is as follows: or, Where, f1 is the stator current frequency; f2 is the motor rotor frequency; s is the slip rate; P is the number of pole pairs of the motor; T1 is the stator current variation period, T1 = 1 / f1; T2 is the rotor current variation period, T2 = 1 / f2; n0 is the synchronous speed of the motor; n is the motor speed.

3. The method for measuring motor speed or rotor frequency based on a three-axis magnetometer according to claim 1, characterized in that: The method of analyzing and obtaining the stator current frequency and slip rate of the motor according to the obtained power frequency magnetic field signal and the slip magnetic field signal includes: According to the obtained power frequency magnetic field signal and slip magnetic field signal, the following formulas are used for decomposition, and the maximum eigenvalue direction is selected for data dimension reduction to obtain a one-dimensional high-frequency magnetic flux signal and a one-dimensional low-frequency magnetic flux signal, respectively. The formulas are as follows: A=USV t ; Using a pre-established regression model, respectively determining the distribution information of the signal power in the frequency domain for the one-dimensional high-frequency magnetic flux signal and the one-dimensional low-frequency magnetic flux signal; The peak frequency output is extracted from the obtained signal power distribution information in the frequency domain to obtain the stator current frequency and slip rate; Among them, U and V are orthogonal matrices, and are the singular vectors of A; S is the singular value of A.

4. The method for measuring motor speed or rotor frequency based on a three-axis magnetometer as claimed in claim 3, characterized in that: Before the step of using the pre-established regression model to determine the distribution information of the signal power in the frequency domain for the one-dimensional high-frequency magnetic flux signal and the one-dimensional low-frequency magnetic flux signal, the testing method further includes: Establish a regression model, the regression model is as follows: x(n)=∑(ai*x(ni))+e(n); Among them, a i is the autoregression coefficient; e(n) is the noise term; x(n) is the signal sequence.

5. The method for measuring motor speed or rotor frequency based on a three-axis magnetometer as claimed in claim 4, characterized in that: The method of using a pre-established regression model to determine the distribution information of the signal power in the frequency domain for the one-dimensional high-frequency magnetic flux signal and the one-dimensional low-frequency magnetic flux signal respectively includes: Among them, σ 2 is the noise variance; j is the imaginary unit; ω is the angular frequency; P(ω) is the distribution information of signal power in the frequency domain.

6. The method for measuring motor speed or rotor frequency based on a three-axis magnetometer as claimed in claim 3, characterized in that: The peak frequency output is extracted from the obtained signal power distribution information in the frequency domain to obtain the stator current frequency and the slip rate, including: According to the peak finding function findpeaks(), the peak frequency output is extracted from the distribution information of the signal power in the frequency domain to obtain the stator current frequency and the slip rate.

7. The method for measuring motor speed or rotor frequency based on a three-axis magnetometer according to claim 1, characterized in that: The three-axis magnetometer is disposed adjacent to the motor and the distance from the motor is 9 cm to 11 cm.

8. A device for measuring motor speed or rotor frequency based on a three-axis magnetometer, characterized in that: include: an acquisition unit, configured to acquire a magnetic flux signal when the motor rotates based on a three-axis magnetometer, wherein the three-axis magnetometer is disposed adjacent to the motor and does not contact the motor; A filtering unit, used to obtain a power frequency magnetic field signal and a slip magnetic field signal of low frequency distribution according to the magnetic flux signal and a predetermined high-pass filter and low-pass filter respectively; An analysis unit, used for analyzing and obtaining the stator current frequency and slip rate of the motor according to the obtained power frequency magnetic field signal and slip magnetic field signal; The calculation unit is used to calculate the motor speed or rotor frequency according to the obtained stator current frequency and the slip rate.

9. A computer device, characterized in that: include: at least one processor; as well as, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method for measuring the motor speed or rotor frequency based on a three-axis magnetometer as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for measuring the motor speed or rotor frequency based on a three-axis magnetometer as claimed in any one of claims 1 to 7 is implemented.

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