A cylindrical linear motor eccentricity detection device and method

Abstract

The present invention discloses a cylindrical linear motor eccentricity detection device and method. The device includes: an induced electromotive force generating device provided on the stator of the cylindrical linear motor; an induced electromotive force collecting device for collecting the induced electromotive force generated by the induced electromotive force generating device; an induced electromotive force processing device for obtaining the data collected by the induced electromotive force collecting device, analyzing and processing the data, and further obtaining the eccentricity fault of the cylindrical linear motor. The induced electromotive force generating device, the induced electromotive force collecting device, and the induced electromotive force processing device are connected in sequence. The method performs fast Fourier transform (FFT) processing on the induced electromotive force signal, obtains the amplitude spectrum of the induced electromotive force of each detection coil in each layer and each phase, calculates and analyzes it, and further obtains the eccentricity type, eccentricity direction, and eccentricity degree of the cylindrical linear motor. The invention has a simple structure, low cost, fast detection speed, and high detection accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of tubular linear motors, and particularly to a tubular linear motor eccentricity detection device and method. Background Art

[0002] The tubular linear motor is an evolution of the rotary motor in terms of structure. When the rotary motor is cut along the radial direction and straightened, a flat linear motor is formed. By winding the flat motor around an axis parallel to the direction of magnetic field movement, a tubular linear motor is constituted.

[0003] A linear motor directly converts electrical energy into mechanical energy of linear motion without an intermediate conversion device, and has a simple structure. Different from ordinary rotary motors and flat linear motors, the tubular linear permanent magnet motor has no end windings, high utilization rate of stator windings, no lateral edge effect, no end leakage magnetic flux and additional impedance. Ideally, the radial pulling forces of the cylindrical mover cancel each other out, and there is no problem of unilateral magnetic pulling force either.

[0004] However, due to errors in the manufacturing and assembly processes and the influence of lateral impact forces during the operation of the motor, the axes of the stator and mover of the tubular permanent magnet linear motor are prone to shift, resulting in eccentricity, causing uneven distribution of air-gap magnetic density, and causing distortion of the air-gap magnetic density of the motor along the circumferential and axial directions, causing the mover to generate torsional and shear stresses, generating vibration noise, and increasing motor losses, etc. Various problems caused by the mover eccentricity fault will always affect the long-term safe and stable operation of the motor. Therefore, studying the eccentricity detection of the tubular permanent magnet linear motor under the eccentric state has very important theoretical and practical significance.

[0005] The research on the motor air-gap eccentricity fault not only plays an important role in accurate online diagnosis and monitoring, but also has far-reaching significance for in-depth study of the mechanism of the eccentricity fault, and then developing new technologies to suppress air-gap eccentricity, and even air-gap adjustment control technologies, etc.

[0006] Regarding the research on the air-gap eccentricity fault detection method, from the perspective of detection methods, there are mainly two aspects. One is non-invasive detection, and the other is invasive detection. For non-invasive detection, it is detected through the existing parameters of the motor or the parameters of the sensor, with poor accuracy, and most methods cannot judge the detection eccentricity direction and eccentricity degree. For invasive detection, it mainly detects the change of the leakage magnetic flux of the detection coil to perform eccentricity detection on it.

[0007] However, during the process of the inventors of the present application implementing the inventive technical solution in the embodiments of the present application, it is found that the above technologies at least have the following technical problems:

[0008] Both the existing non-invasive detection and invasive detection are aimed at rotary motors, and the existing detection methods focus on the magnetic leakage spectrum and current spectrum. There is no detection method for the eccentricity fault of tubular permanent magnet linear motors yet. Summary of the Invention

[0009] By providing a tubular linear motor eccentricity detection device and method in an embodiment of the present application, the blank in the prior art that the detection methods are all aimed at rotary motors and there is no detection method for the eccentricity fault of tubular permanent magnet linear motors is filled. The device and method provided by the present application can detect the eccentricity of the tubular linear motor, can diagnose the eccentricity type, eccentricity direction and eccentricity degree of the motor at the same time, and have a fast detection speed and good accuracy.

[0010] An embodiment of the present application provides a tubular linear motor eccentricity detection device, including:

[0011] An induced electromotive force generating device provided on the stator of the tubular linear motor;

[0012] An induced electromotive force collecting device for collecting the induced electromotive force generated by the induced electromotive force generating device;

[0013] An induced electromotive force processing device for obtaining the data collected by the induced electromotive force collecting device, analyzing and processing it, and then obtaining the eccentricity fault of the tubular linear motor;

[0014] The induced electromotive force generating device, the induced electromotive force collecting device and the induced electromotive force processing device are connected in sequence.

[0015] Preferably, the induced electromotive force generating device includes a detection coil, the detection coil is arranged in the outer stator slot of the tubular linear motor, the detection coil includes upper, middle and lower layers, and the detection coils of each layer are arranged in a circular shape. There are p detection coils arranged in each layer, and p is an even number greater than or equal to 4.

[0016] More preferably, the ends of adjacent detection coils are closely attached.

[0017] Preferably, the induced electromotive force collecting device is an oscilloscope, and the input end of the oscilloscope is connected to the induced electromotive force generating device.

[0018] Preferably, the induced electromotive force processing device includes a memory and a processor connected to each other, and the memory is connected to the output end of the induced electromotive force collecting device.

[0019] An embodiment of the present application also provides a tubular linear motor eccentricity detection method, which uses the above-mentioned tubular linear motor eccentricity detection device, and the method steps are:

[0020] Start the cylindrical linear motor and detect the induced electromotive force generated by the coil;

[0021] The induced electromotive force acquisition device acquires the induced electromotive force signal and sends it to the induced electromotive force processing device;

[0022] The induced electromotive force processing device performs FFT (Fast Fourier Transform) processing on the induced electromotive force signal, obtains the amplitude spectra of the induced electromotive forces of the detection coils of each layer and each phase, calculates and analyzes them, and then obtains the eccentricity type, eccentricity direction, and eccentricity degree of the cylindrical linear motor.

[0023] Preferably, the specific process of performing FFT processing on the induced electromotive force signal and obtaining the amplitude spectra of the induced electromotive forces of the detection coils of each layer and each phase is as follows:

[0024] The induced electromotive forces measured by the upper, middle, and lower three-layer i-phase detection coils are respectively recorded as functions of the time series number n, u hi (n), u mi (n), u li (n), where i = 1, 2,..., p, p is an even number greater than or equal to 4, and perform FFT processing on them respectively:

[0025]

[0026]

[0027]

[0028] Among them, U hi (k), U mi (k), U li (k) are respectively the frequency spectrum sequences obtained by FFT of the induced electromotive forces measured by the upper, middle, and lower three-layer i-phase detection coils, N is the number of points of FFT, k is the ordinal number of the frequency spectrum sequence obtained by FFT, k = 0, 1,..., N - 1;

[0029] According to the frequency spectrum sequences U hi (k), U mi (k), U li (k), find the maximum values U * ki , U * mi , U * li :

[0030]

[0031]

[0032]

[0033] Furthermore, the eccentric types of the cylindrical linear motor include static eccentricity and skew eccentricity. The specific calculation and analysis process for static eccentricity detection is as follows:

[0034] A. Detection of static eccentricity direction

[0035] The direction of static eccentricity is determined according to the maximum value U of the amplitude spectrum of the induced electromotive force of the middle-layer detection coil: * mi If the maximum value of the amplitude spectrum of the induced electromotive force measured by the i-th phase detection coil in the middle layer s is the largest among all p-phase detection coils, that is:

[0036]

[0037] Then the static eccentricity direction is from the stator center to the direction of the i-th phase detection coil; s

[0038] B. Calculation of static eccentricity degree

[0039] Denote the opposite side of the i-th phase detection coil in the middle layer as the i-th phase detection coil in the middle layer. Since the number of phases p of the detection coil is even, i can be calculated by the following formula: s ss ss :

[0040]

[0041] According to formulas (2) and (5), calculate the maximum value of the amplitude spectrum of the induced electromotive force measured by the i-th phase detection coil in the middle layer ss Combined with The static eccentricity degree detection index U s can be defined as:

[0042]

[0043] U s and the static eccentricity degree e s satisfy the following relationship:

[0044] e s = aU s + b (10)

[0045] where a and b are both constants and are related to the properties of the motor itself.

[0046] Furthermore, the specific calculation and analysis process for skew eccentricity detection is as follows:

[0047] ​​​​​A. Oblique Eccentricity Direction Detection

[0048] The direction of the oblique eccentricity is determined according to the maximum values U * ki and U * li of the amplitude spectra of the induced electromotive forces of the upper and lower layer detection coils: If the difference between the maximum values of the amplitude spectra of the induced electromotive forces measured by the i o -phase detection coils in the upper and lower layers is the largest among all p-phase detection coils, that is:

[0049]

[0050] then there is an oblique eccentricity in the motor where the upper end inclines towards the i o -phase detection coil in the upper layer and the lower end deviates from the i o -phase detection coil in the lower layer;

[0051] B. Oblique Eccentricity Degree Calculation

[0052] Denote the opposite sides of the i o -phase detection coils in the upper and lower layers as the i oo -phase detection coils in the upper and lower layers. Since the number of phases p of the detection coils is even, the i oo can be calculated by the following formula:

[0053]

[0054] According to formulas (1), (3), (4), and (6), calculate the difference between the maximum values of the amplitude spectra of the induced electromotive forces measured by the i oo -phase detection coils in the upper and lower layers Combined with the oblique eccentricity degree detection index U o can be defined as:

[0055]

[0056] U o and the oblique eccentricity degree e o are related as follows:

[0057] e o = cU o + d (14)

[0058] where c and d are both constants related to the properties of the motor itself.

[0059] Furthermore, the method for detecting the eccentricity type of the cylindrical linear motor is as follows:

[0060] When the eccentricity type is unknown, by judging the static eccentricity degree detection index U s and the oblique eccentricity degree detection index U​o Whether it is greater than a certain threshold value to determine whether static eccentricity and skew eccentricity exist;

[0061] A) Threshold value U of the static eccentricity degree detection index s0 Determined according to the theoretical skew eccentricity situation of the motor, and the calculation method is divided into the following three steps:

[0062] The first step: According to the skew eccentricity direction detection method, find out the theoretical skew eccentricity direction of the motor;

[0063] The second step: Measure the induced electromotive force of each phase detection coil in the middle layer when the skew eccentricity in the said direction reaches the theoretical maximum value, and find the maximum value of the amplitude spectrum of the said induced electromotive force through formulas (2) and (5);

[0064] The third step: Substitute the maximum value of the amplitude spectrum of the said induced electromotive force into formulas (7)-(9) to find the corresponding static eccentricity degree detection index, and this index is the threshold value U of the static eccentricity degree detection index s0 ;

[0065] B) Threshold value U of the skew eccentricity degree detection index o0 Determined according to the theoretical static eccentricity situation of the motor, and the calculation method is also divided into three steps:

[0066] The first step: According to the said static eccentricity direction detection method, find out the theoretical static eccentricity direction of the motor;

[0067] The second step: Measure the induced electromotive force of each phase detection coil in the upper and lower layers when the static eccentricity in the said direction reaches the theoretical maximum value, and then find the maximum value of the amplitude spectrum of the said induced electromotive force through formulas (1), (3), (4), and (6);

[0068] The third step: Substitute the maximum value of the amplitude spectrum of the said induced electromotive force into formulas (11)-(13) to find the corresponding skew eccentricity degree detection index, and this index is the threshold value U of the skew eccentricity degree detection index o0 ;

[0069] When U s > U s0 It indicates that the motor has static eccentricity;

[0070] When U o > U o0 It indicates that the motor has skew eccentricity;

[0071] When U s > U s0 and U o > U o0 hold simultaneously, it indicates that the motor has mixed eccentricity;

[0072] After determining the type of eccentricity, the directions and degrees of static eccentricity and skew eccentricity are obtained according to the static eccentricity detection method and the skew eccentricity detection method respectively.

[0073] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0074] 1. The present application provides a device capable of detecting the eccentricity of a cylindrical linear motor. The device has a simple structure, low cost, and is convenient for popularization and use.

[0075] 2. The present application provides a method capable of detecting the eccentricity of a cylindrical linear motor. By using the induced electromotive force signal to detect the air-gap eccentricity fault of the cylindrical linear motor, an invasive detection is used, and a method for detecting the induced electromotive force of a layered and phase-divided detection coil is designed. The result is subjected to FFT fast Fourier transform and processing to obtain the amplitude spectrum of the induced electromotive force of each layer and each phase of the detection coil, and it is calculated, analyzed and processed, and then eccentricity diagnosis is carried out, and the eccentricity type, eccentricity direction and eccentricity degree of the motor can be diagnosed simultaneously.

[0076] 3. The detection device and method provided by the present application have a fast detection speed and high accuracy, and provide technical support for the technology of suppressing air-gap eccentricity and motor maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 is a structural block diagram of the cylindrical linear motor eccentricity detection device provided in the embodiments of the present application;

[0078] Figure 2 is a schematic diagram of arranging upper, middle and lower three-layer detection coils on the stator of the cylindrical linear motor in the embodiments of the present application;

[0079] Figure 3 is a schematic diagram of the structure of the detection coil in the embodiments of the present application;

[0080] Figure 4 is a flowchart of the cylindrical linear motor eccentricity detection method in the embodiments of the present application;

[0081] Figure 5 is a schematic diagram of the maximum value of the amplitude spectrum of the induced electromotive force of each phase of the middle layer detection coil under different static eccentricities;

[0082] Figure 6 is e s -U s scatter plot and regression equation schematic diagram;

[0083] Figure 7 is a schematic diagram of the difference between the maximum values of the amplitude spectra of the induced electromotive forces of each phase of the upper and lower layer detection coils under different skew eccentricities;

[0084] Figure 8 is eo -U o Scatter diagram and schematic diagram of regression equation

[0085] Figure 9 Schematic diagram of the difference between the maximum values of the induced electromotive force amplitude spectra of each phase of the upper and lower detection coils under mixed eccentricity

[0086] Figure 10 Schematic diagram of the maximum value of the induced electromotive force amplitude spectrum of each phase of the middle detection coil under maximum oblique eccentricity

[0087] Figure 11 Schematic diagram of the maximum value of the induced electromotive force amplitude spectrum of each phase of the middle detection coil under mixed eccentricity

[0088] Figure 12 Schematic diagram of the difference between the maximum values of the induced electromotive force amplitude spectra of each phase of the upper and lower detection coils under maximum static eccentricity Specific implementation manner

[0089] By providing a cylindrical linear motor eccentricity detection device and method in the embodiments of the present application, the blank in the prior art that the detection methods are all for rotary motors and there is no eccentricity fault detection method for cylindrical permanent magnet linear motors is filled

[0090] The technical solutions in the embodiments of the present application are to solve the above technical problems, and the general idea is as follows

[0091] Design a cylindrical linear motor eccentricity detection device, arrange three layers of upper, middle and lower layers on the stator of the cylindrical linear motor, and arrange p detection coils on each layer, where p is an even number greater than or equal to 4. The more detection coils are arranged on each layer, the more accurate the eccentricity detection direction is. The detection coils are connected to the induced electromotive force acquisition device, and the induced electromotive force acquisition device is then connected to the induced electromotive force processing device

[0092] When the cylindrical linear motor has an eccentricity fault, the symmetric structure of the motor is damaged, and the air gap length between the stator and the rotor becomes uneven. According to the change of the induced electromotive force parameters of the detection coils under the eccentricity of the cylindrical linear motor, online detection is carried out

[0093] Specifically, the air gap eccentricity fault is detected through the induced electromotive force signal, and an invasive detection is used to design a method for detecting the induced electromotive force of the hierarchical and phase-separated detection coils. The result is subjected to FFT (Fast Fourier Transformation) and processed to obtain the amplitude spectra of the induced electromotive forces of the detection coils of each layer and each phase, and calculate and analyze them to perform eccentricity diagnosis, which can simultaneously diagnose the eccentricity type, eccentricity direction and eccentricity degree of the cylindrical linear motor

[0094] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0095] Figure 1 This is a structural block diagram of the eccentric detection device for a cylindrical linear motor provided in an embodiment of the present application. The eccentric detection device for the cylindrical linear motor includes:

[0096] An induced electromotive force generating device provided on the stator of the cylindrical linear motor;

[0097] An induced electromotive force collecting device for collecting the induced electromotive force generated by the induced electromotive force generating device;

[0098] An induced electromotive force processing device for obtaining the data collected by the induced electromotive force collecting device, performing analysis and processing, and then obtaining the eccentric fault of the cylindrical linear motor;

[0099] The induced electromotive force generating device, the induced electromotive force collecting device, and the induced electromotive force processing device are connected in sequence.

[0100] Combined with Figure 2 , the induced electromotive force generating device includes a detection coil 2. Upper, middle, and lower layers of detection coils 2 are arranged in the slots of the outer stator 1 of the cylindrical linear motor. p detection coils are arranged in each layer, and p is an even number greater than or equal to 4. The more detection coils are arranged in each layer, the more accurate the eccentric detection direction is.

[0101] Combined with Figure 3 , a single detection coil is arc-shaped along the length direction. The detection coils in each layer are arranged in a circular shape. The smaller the gap between adjacent detection coils, the more accurate the eccentric detection direction is.

[0102] In a certain preferred embodiment, the end of a single detection coil is a planar structure, and the ends of adjacent detection coils are in close contact with a zero gap.

[0103] The induced electromotive force collecting device is an oscilloscope. The input end of the oscilloscope is connected to the detection coil 2. The oscilloscope collects the induced electromotive force signal of the detection coil 2 and displays the waveform curve of the amplitude of the induced electromotive force signal changing with time on the screen.

[0104] The induced electromotive force processing device includes a memory and a processor connected to each other. The memory is connected to the output end of the oscilloscope. The memory obtains the induced electromotive force signal output by the oscilloscope and stores it. The processor performs FFT fast Fourier transform processing on the induced electromotive force signal, calculates the amplitude spectrum of the induced electromotive force of each layer and each phase of the detection coil, and performs calculation and analysis on it, so as to perform eccentric diagnosis, and can simultaneously diagnose the eccentric type, eccentric direction, and eccentric degree of the cylindrical linear motor.

[0105] Figure 4 This is the flowchart of the eccentric detection method for the cylindrical linear motor in the embodiments of this application. The detection method of the above-mentioned cylindrical linear motor eccentric detection device is as follows:

[0106] Start the cylindrical linear motor, and the detection coil generates an induced electromotive force. Denote the induced electromotive forces measured by the upper (h), middle (m), and lower (l) three-layer phase-i detection coils as functions of the time sequence number n, u hi (n), u mi (n), u li (n), where i = 1, 2,..., p, and p is an even number greater than or equal to 4. Perform FFT (Fast Fourier Transform) processing on them respectively:

[0107]

[0108]

[0109]

[0110] Among them, U hi (k), U mi (k), U li (k) are the spectral sequences obtained by FFT of the induced electromotive forces measured by the upper, middle, and lower layer phase-i detection coils respectively. N is the number of points of FFT, k is the ordinal number of the spectral sequence obtained by FFT, and k = 0, 1,..., N - 1. Next, according to the spectral sequences U hi (k), U mi (k), U li (k), find the maximum values U * ki 、U * mi 、U * li :

[0111]

[0112]

[0113]

[0114] 1. Static eccentricity detection method

[0115] (1) Static eccentricity direction detection method

[0116] The direction of static eccentricity is determined according to the maximum value U * mi of the amplitude spectrum of the induced electromotive force of the middle layer detection coil: If the middle layer phase-i sThe maximum value of the amplitude spectrum of the induced electromotive force measured by the phase detection coil is the largest among all p phase detection coils, that is:

[0117]

[0118] Then the direction of static eccentricity is from the center of the stator to the i s th phase detection coil.

[0119] (2) Method for calculating the degree of static eccentricity

[0120] Denote the opposite side of the i s th phase detection coil in the middle layer as the i ss th phase detection coil in the middle layer. Since the number of phases p of the detection coil is even, i can be calculated by the following formula ss :

[0121]

[0122] According to formulas (2) and (5), calculate the maximum value of the amplitude spectrum of the induced electromotive force measured by the i ss th phase detection coil in the middle layer Combined with the detection index U of the static eccentricity degree can be defined s :

[0123]

[0124] U s and the static eccentricity degree e s are related as follows:

[0125] e s = aU s + b (10)

[0126] where a and b are both constants, related to the properties of the motor itself, and can be calculated by finding the regression equation from experimental data. Therefore, in the actual scenario, as long as the induced electromotive forces of each phase detection coil in the middle layer are measured, the static eccentricity degree e can be obtained according to formulas (2), (5), (7) to (10) s .

[0127] 2. Oblique eccentricity detection method

[0128] (1) Method for detecting the direction of oblique eccentricity

[0129] The direction of oblique eccentricity is determined according to the maximum values U * ki 、U * li of the amplitude spectra of the induced electromotive forces of the upper and lower layer detection coils: If the i oThe difference between the maximum values of the amplitude spectra of the induced electromotive forces measured by the phase detection coils The largest among all p phase detection coils, that is:

[0130]

[0131] Then there is an inclined eccentricity in the motor where the upper end inclines towards the upper layer of the i o phase detection coil and the lower end deviates from the lower layer of the i o phase detection coil.

[0132] (2) Method for calculating the degree of inclined eccentricity

[0133] Denote the opposite sides of the upper and lower layer i o phase detection coils as the upper and lower layer i oo phase detection coils. Since the number of phases p of the detection coils is even, the i can be calculated through the following formula oo :

[0134]

[0135] Calculate the difference between the maximum values of the amplitude spectra of the induced electromotive forces measured by the upper and lower layer i oo phase detection coils according to formulas (1), (3), (4), and (6) Combined with The detection index U of the inclined eccentricity can be defined o :

[0136]

[0137] U o And the degree of inclined eccentricity e o There is the following relationship:

[0138] e o = cU o + d (14)

[0139] Where c and d are both constants, related to the properties of the motor itself, and can be calculated by finding the regression equation from experimental data. Therefore, in the actual scenario, as long as the induced electromotive forces of the phase detection coils of the upper and lower layers are measured, the degree of inclined eccentricity e can be obtained according to formulas (1), (3), (4), (6), (11)-(14) o .

[0140] 3. Method for detecting the type of eccentricity

[0141] When the type of eccentricity is unknown, it can be determined whether static eccentricity and inclined eccentricity exist by judging whether the static eccentricity detection index U s and the inclined eccentricity detection index U o are greater than a certain threshold.

[0142] A) Threshold U of the static eccentricity degree detection index s0 It needs to be determined according to the theoretical skew eccentricity situation of the motor, and the calculation method is divided into the following three steps:

[0143] The first step: According to the skew eccentricity direction detection method described above, find out the theoretical skew eccentricity direction of the motor;

[0144] The second step: Measure the induced electromotive force of each phase detection coil in the middle layer when the skew eccentricity in this direction reaches the theoretical maximum value, and find the maximum value of the amplitude spectrum of these induced electromotive forces through formulas (2) and (5);

[0145] The third step: Substitute the maximum value of the amplitude spectrum of these induced electromotive forces into formulas (7)-(9) to find the corresponding static eccentricity degree detection index, and this index is the threshold U of the static eccentricity degree detection index s0 .

[0146] B) Threshold U of the skew eccentricity degree detection index o0 It needs to be determined according to the theoretical static eccentricity situation of the motor, and the calculation method is also divided into three steps:

[0147] The first step: According to the static eccentricity direction detection method described above, find out the theoretical static eccentricity direction of the motor;

[0148] The second step: Measure the induced electromotive force of each phase detection coil in the upper and lower layers when the static eccentricity in this direction reaches the theoretical maximum value, and then find the maximum value of the amplitude spectrum of these induced electromotive forces through formulas (1), (3), (4), and (6);

[0149] The third step: Substitute the maximum value of the amplitude spectrum of these induced electromotive forces into formulas (11)-(13) to find the corresponding skew eccentricity degree detection index, and this index is the threshold U of the skew eccentricity degree detection index o0 .

[0150] When U s >U s0 , it indicates that the motor has static eccentricity; when U o >U o0 , it indicates that the motor has skew eccentricity; when U s >U s0 and U o >U o0 hold simultaneously, it indicates that the motor has mixed eccentricity. After determining the eccentricity type, the directions and degrees of static eccentricity and skew eccentricity can be found respectively according to the static eccentricity detection method and skew eccentricity detection method described above.

[0151] The following is illustrated with a specific example.

[0152] Arrange upper, middle, and lower three - layer detection coils in the slots of the outer stator of the cylindrical linear motor. Each layer arranges 8 detection coils, as Figure 3 shown.

[0153] 1. Static eccentricity detection

[0154] First, obtain the induced electromotive force measured by each phase detection coil in the middle layer under different static eccentricities. Then, according to formulas (1) - (6), find the maximum value U of the amplitude spectrum of the induced electromotive force measured by each phase detection coil in the middle layer * mi . Since there are 8 phases of detection coils in the prototype, so i = 0, 1, …, 8.

[0155] Make a line graph of the maximum value U of the amplitude spectrum of the induced electromotive force of each phase detection coil in the middle layer under the cases of no eccentricity and five static eccentricities, and the result is as * mi shown, Figure 5 in which, "none" represents no eccentricity, and "static 0.5", "static 1", "static 1.5", "static 2", "static 2.4" represent the static eccentricity distances of 0.5mm, 1mm, 1.5mm, 2mm, and 2.4mm respectively. From Figure 5 it can be seen that when there is static eccentricity, the maximum value of U of the first - phase detection coil Figure 5 is the largest. Therefore, in this embodiment, the directions of the five static eccentricities are all from the center of the stator to the first - phase detection coil, that is, i * mi = 1. s = 1.

[0156] Table 1 U under different static eccentricities s

[0157]

[0158] According to formula (8), it is found that the coil opposite to the first - phase detection coil is the fifth - phase detection coil, that is, i ss = 5. Substitute i s , i ss into formula (9) to calculate the static eccentricity degree detection index U s under the cases of no eccentricity and five static eccentricities, and the results are shown in Table 1. Make a scatter plot of the results in Table 1 as Figure 6 shown.

[0159] According to Figure 6 the scatter plot of [], the regression equation can be obtained, and the constants a = 1.0316 and b = 0.0064 in formula (10) can be found. The regression equation R 2 score is 0.9995, so the fitting effect of this equation is excellent. Furthermore, when the static eccentricity direction is from the center of the stator to the first - phase detection coil, it can be obtained through

[0160] e s= 1.0316U s + 0.0064

[0161] Calculate the static eccentricity degree e s 。

[0162] 2. Oblique eccentricity detection

[0163] First, obtain the induced electromotive forces measured by the detection coils of each phase in the upper and lower layers under different oblique eccentricities, and then calculate the maximum values U of the amplitude spectra of the induced electromotive forces measured by the detection coils of each phase in the upper and lower layers according to formulas (1)-(6) * hi 、U * li 。Since there are 8 phases in the prototype detection coils, i = 0, 1,..., 8

[0164] Take the difference U between the maximum values of the amplitude spectra of the induced electromotive forces of the detection coils of each phase in the upper and lower layers under the cases of no eccentricity and five kinds of oblique eccentricities * hi -U * li Make a line graph, and the result is as Figure 7 shown Figure 7 where no representative means no eccentricity, and oblique 0.5, oblique 1, oblique 1.5, oblique 2, and oblique 2.3 respectively represent oblique eccentric angles of 0.5 degrees, 1 degree, 1.5 degrees, 2 degrees, and 2.3 degrees. It can be seen from Figure 7 that when there is oblique eccentricity, the difference U * hi -U * li of the first-phase detection coil is the largest. Therefore, in this embodiment, all five kinds of oblique eccentricities are the oblique eccentricities with the upper end inclined towards the first-phase detection coil in the upper layer and the lower end deviating from the first-phase detection coil in the lower layer, that is, i o = 1

[0165] Table 2 U under different oblique eccentricity conditions o

[0166]

[0167] According to formula (12), it is found that the coil opposite to the first-phase detection coil is the fifth-phase detection coil, that is, i oo = 5. Substitute i o 、i oo into formula (13) to calculate the oblique eccentricity degree detection index U o under the cases of no eccentricity and five kinds of oblique eccentricities. The results are shown in Table 2. Make a scatter plot of the results in Table 2 as Figure 8 shown

[0168] According to the scatter plot Figure 8To find the regression equation, the constants c = 0.7229 and d = -0.0338 in equation (14) can be obtained, and the regression equation R 2 The score is 0.9991, so the fitting effect of this equation is excellent. Furthermore, when the direction of the oblique eccentricity is that the upper end inclines towards the first-phase detection coil of the upper layer and the lower end deviates from the first-phase detection coil of the lower layer, it can be obtained through

[0169] e o = 0.7229U o -0.0338

[0170] to calculate the degree of oblique eccentricity e o .

[0171] 3. Eccentricity type detection

[0172] Set the static eccentricity with the direction from the center of the stator to the first-phase detection coil and a magnitude of 1.0 mm, and the mixed eccentricity of the static eccentricity and the oblique eccentricity with the direction that the upper end inclines towards the first-phase detection coil of the upper layer, the lower end deviates from the first-phase detection coil of the lower layer, and a magnitude of 0.5°. According to the eccentricity type detection method proposed in this application, predict the directions and degrees of the static eccentricity and the oblique eccentricity, and compare the prediction results with the actual eccentricity situation to prove the effectiveness of the eccentricity type detection method proposed in this application.

[0173] 3.1 Judgment and detection of static eccentricity

[0174] In the first step, according to the oblique eccentricity detection method proposed above, calculate the difference U * hi -U * li between the maximum values of the amplitude spectra of the induced electromotive forces measured by the detection coils of each phase in the upper and lower layers under the given mixed eccentricity situation, and the result is as Figure 9 shown. It can be seen from Figure 9 that under the given mixed eccentricity condition, the difference U * hi -U * li of the first-phase detection coil is the largest. Therefore, theoretically, there is an oblique eccentricity in the motor where the upper end inclines towards the first-phase detection coil of the upper layer and the lower end deviates from the first-phase detection coil of the lower layer.

[0175] In the second step, calculate the maximum values of the amplitude spectra of the induced electromotive forces of the detection coils of each phase in the middle layer when the direction of the oblique eccentricity is that the upper end inclines towards the first-phase detection coil of the upper layer and the lower end deviates from the first-phase detection coil of the lower layer, and the degree reaches the theoretical maximum value. For the prototype, the theoretical maximum value of the oblique eccentricity degree is 2.3°. At this time, the maximum values of the amplitude spectra of the induced electromotive forces of the detection coils of each phase in the middle layer are as Figure 10 shown.

[0176] In the third step, substitute the maximum value of the amplitude spectrum of these induced electromotive forces into Formulas (7)-(9) to obtain the corresponding static eccentricity degree detection index as 0.455. The value of this index is the static eccentricity degree detection index threshold U s0 , that is, U s0 = 0.455.

[0177] Now calculate the maximum value of the amplitude spectrum of the induced electromotive force of each phase detection coil in the middle layer under the condition of mixed eccentricity. The results are as Figure 11 shown. It can be seen that when there is mixed eccentricity, the maximum value of the amplitude spectrum of the induced electromotive force of the first-phase detection coil in the middle layer is the largest. Therefore, theoretically, there is a static eccentricity in the motor in the direction from the center of the stator to the first-phase detection coil. Furthermore, according to Formulas (8) and (9), the static eccentricity degree detection index U s = 1.037 can be obtained. Since 1.037 > U s0 , there is static eccentricity in the motor; substitute U s into Formula (15) to obtain the predicted value of the static eccentricity degree e s as 1.05 mm.

[0178] Comparing with the actual static eccentricity situation, the predicted static eccentricity direction is consistent with the actual one, and the error of the static eccentricity degree is only 0.05 mm. It can be seen that the prediction result has high accuracy.

[0179] 3.2 Judgment and Detection of Oblique Eccentricity

[0180] In the first step, according to the analysis in the judgment and detection of static eccentricity, there is theoretically a static eccentricity in the motor in the direction from the center of the stator to the first-phase detection coil.

[0181] In the second step, calculate the difference between the maximum values of the amplitude spectra of the induced electromotive forces measured by the upper and lower layer phase detection coils when the static eccentricity direction is from the center of the stator to the first-phase detection coil and the degree reaches the theoretical maximum value. For the prototype, the theoretical maximum value of the static eccentricity degree is 2.4 mm. At this time, the difference between the maximum values of the amplitude spectra of the induced electromotive forces measured by the upper and lower layer phase detection coils is as Figure 12 shown.

[0182] In the third step, substitute the difference between the maximum values of the amplitude spectra of these induced electromotive forces into Formulas (11)-(13) to obtain the corresponding oblique eccentricity degree detection index as 0.125. The value of this index is the oblique eccentricity degree detection index threshold U o0 , that is, U o0 = 0.125.

[0183] In the judgment and detection of static eccentricity, it has been obtained that there is theoretically an oblique eccentricity in the motor with the upper end tilting towards the first-phase detection coil in the upper layer and the lower end deviating from the first-phase detection coil in the lower layer. Furthermore, according to Formulas (12) and (13), the oblique eccentricity degree detection index U o= 0.725. Since 0.725 > U o0 , there is an inclined eccentricity in the motor; substitute U o into formula (16) to obtain the degree of inclined eccentricity e o The predicted value is 0.47°.

[0184] Comparing with the actual inclined eccentricity situation, the predicted inclined eccentricity direction is consistent with the actual one, and the error of the inclined eccentricity degree is only 0.03°. It can be seen that the prediction result has high accuracy.

[0185] It should be understood that the orientation terms such as up, down, left, right, front, back, front side, back side, top, bottom, etc. mentioned or possibly mentioned in this specification are defined relative to the structures shown in the respective drawings. They are relative concepts, and thus may change accordingly according to their different positions and different usage states. Therefore, these or other orientation terms should not be construed as restrictive terms.

[0186] The above is only a preferred embodiment of the present application, and does not impose any formal or substantial restrictions on the present application. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the method of the present application, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present application. For those skilled in the art, without departing from the spirit and scope of the present application, any equivalent changes, modifications, and evolutions made by using the technical content disclosed above shall be equivalent embodiments of the present application; at the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the essential technology of the present application shall still fall within the scope of the technical solution of the present application.

Claims

1. A method for detecting eccentricity of a cylindrical linear motor, characterized in that, Adopt a cylindrical linear motor eccentricity detection device, and the cylindrical linear motor eccentricity detection device includes: An induced electromotive force generating device provided on the stator of the cylindrical linear motor; An induced electromotive force acquisition device for acquiring the induced electromotive force generated by the induced electromotive force generating device; An induced electromotive force processing device for obtaining the data acquired by the induced electromotive force acquisition device, analyzing and processing it, and then obtaining the eccentricity fault of the cylindrical linear motor; The induced electromotive force generating device, the induced electromotive force acquisition device, and the induced electromotive force processing device are connected in sequence; The induced electromotive force generating device includes a detection coil, the detection coil is arranged in the outer stator slot of the cylindrical linear motor, the detection coil includes upper, middle, and lower layers, each layer of the detection coil is arranged in a circular shape, and p detection coils are arranged in each layer, where p is an even number greater than or equal to 4; A single detection coil is arc-shaped along the length direction, the end of a single detection coil is a planar structure, and the ends of adjacent detection coils are closely attached; The method steps are as follows: Start the cylindrical linear motor, and the detection coil generates an induced electromotive force; The induced electromotive force acquisition device acquires the induced electromotive force signal and sends it to the induced electromotive force processing device; The induced electromotive force processing device performs FFT fast Fourier transform processing on the induced electromotive force signal, obtains the amplitude spectrum of the induced electromotive force of each layer and each phase of the detection coil, and performs calculation and analysis on it to obtain the eccentricity type, eccentricity direction, and eccentricity degree of the cylindrical linear motor; The eccentricity types of the cylindrical linear motor include static eccentricity and skew eccentricity; the specific calculation and analysis process for static eccentricity detection is as follows: A. Static eccentricity direction detection The direction of the static eccentricity is determined according to the maximum value U of the amplitude spectrum of the induced electromotive force of the middle-layer detection coil * mi as follows: If the maximum value of the amplitude spectrum of the induced electromotive force measured by the i s -th phase detection coil in the middle layer is the largest among all p-phase detection coils, that is: The static eccentricity direction is from the center of the stator to the direction of the i s -phase detection coil; B. Static eccentricity degree calculation Denote the i-th layer in the middle s The opposite side of the phase detection coil is the i-th layer in the middle ss phase detection coil. Since the number of phases p of the detection coil is even, i can be calculated by the following formula ss : Calculate the maximum value of the amplitude spectrum of the induced electromotive force measured by the phase detection coil for the i-th layer according to Formulas (2) and (5). ss The maximum value of the amplitude spectrum of the induced electromotive force measured by the phase detection coil Combined with The static eccentricity degree detection index U can be defined s : U s and the static eccentricity e s satisfy the following relationship: e s = aU s + b(10) Where a and b are both constants, related to the properties of the motor itself; The specific calculation and analysis process for skew eccentricity detection is as follows: A. Skew eccentricity direction detection The direction of the skew eccentricity is determined according to the maximum values U * ki , U * li of the amplitude spectra of the induced electromotive forces of the upper and lower detection coils: If the difference between the maximum values of the amplitude spectra of the induced electromotive forces measured by the i o -phase detection coils of the upper and lower layers is the largest among all p-phase detection coils, that is: ​ Then there is an inclined eccentricity in the motor, where the upper end inclines towards the upper layer of the i-th o phase detection coil, and the lower end deviates from the lower layer of the i-th o phase detection coil. B. Skew eccentricity degree calculation Record the i-th of the upper and lower layers o The opposite sides of the i-th phase detection coils of the upper and lower layers are oo the i-th phase detection coils. Since the number of phases p of the detection coils is even, i can be calculated by the following formula oo : Calculate the difference between the maximum values of the amplitude spectra of the induced electromotive forces measured by the upper and lower layer's i-th oo phase detection coils according to formulas (1), (3), (4), and (6). Combined with the skewed eccentricity detection index U can be defined as o : U o and the degree of diagonal eccentricity e o satisfy the following relationship: e o = cU o + d(14) Where c and d are both constants, related to the properties of the motor itself.

2. The eccentric detection method of the cylindrical linear motor according to claim 1, characterized in that, The induced electromotive force acquisition device is an oscilloscope, and the input end of the oscilloscope is connected to the induced electromotive force generating device.

3. The eccentric detection method of the cylindrical linear motor according to claim 1, characterized in that The induced electromotive force processing device includes a memory and a processor connected to each other, and the memory is connected to the output end of the induced electromotive force acquisition device.

4. The eccentric detection method of the cylindrical linear motor according to claim 1, characterized in that The specific process of performing FFT fast Fourier transform processing on the induced electromotive force signal and obtaining the amplitude spectrum of the induced electromotive force of each layer and each phase of the detection coil is as follows: The induced electromotive forces measured by the upper, middle, and lower three-layer phase-i detection coils are respectively denoted as functions of the time series number n, u hi (n), u mi (n), u li (n), where i = 1, 2, …, p, p is an even number greater than or equal to 4, and perform FFT (Fast Fourier Transform) processing on them respectively: where U hi (k), U mi (k), U li (k) are the spectrum sequences obtained by FFT of the induced electromotive forces measured by the i-th phase detection coils in the upper, middle, and lower layers respectively, N is the number of points of FFT, k is the ordinal number of the spectrum sequence obtained by FFT, and k = 0, 1, …, N - 1; According to the spectrum sequence U hi (k), U mi (k), U li (k), find the maximum values U * ki of the amplitude spectra of the induced electromotive forces measured by the i-th phase detection coils in the upper, middle, and lower layers, * mi U * li :

5. The eccentric detection method of the cylindrical linear motor according to claim 1, characterized in that, The method for detecting the eccentricity type of the cylindrical linear motor is as follows: When the eccentricity type is unknown, the static eccentricity degree detection index U is judged s and the skew eccentricity degree detection index U o to determine whether static eccentricity and skew eccentricity exist by whether they are greater than a certain threshold value; A) Static eccentricity degree detection index threshold U s0 Determined according to the theoretical skew eccentricity of the motor, and the calculation method is divided into the following three steps: The first step: According to the skew eccentricity direction detection method, find out the theoretically existing skew eccentricity direction of the motor; The second step: Measure the induced electromotive force of each phase of the middle layer detection coil when the skew eccentricity in the direction reaches the theoretical maximum value, and obtain the maximum value of the amplitude spectrum of the induced electromotive force through formulas (2) and (5); Step 3: Substitute the maximum value of the amplitude spectrum of the induced electromotive force into formulas (7)-(9) to obtain the corresponding static eccentricity detection index, which is the threshold U of the static eccentricity detection index s0 ; B) Oblique Eccentricity Detection Index Threshold U o0 Determined according to the theoretical static eccentricity of the motor, and the calculation method is also divided into three steps: The first step: According to the static eccentricity direction detection method, find out the theoretically existing static eccentricity direction of the motor; The second step: Measure the induced electromotive force of each phase of the upper and lower layer detection coils when the static eccentricity in the direction reaches the theoretical maximum value, and then obtain the maximum value of the amplitude spectrum of the induced electromotive force through formulas (1), (3), (4), and (6); Step 3: Substitute the maximum value of the amplitude spectrum of the induced electromotive force into formulas (11)-(13) to obtain the corresponding detection index of the degree of skew eccentricity, which is the threshold U of the detection index of the degree of skew eccentricity o0 ; When U s > U s0 it indicates that there is static eccentricity in the motor; When U o >U o0 it indicates that there is an inclined eccentricity in the motor; When U s > U s0 and U o > U o0 hold simultaneously, it indicates that the motor has a mixed eccentricity; After determining the type of eccentricity, the directions and degrees of static eccentricity and inclined eccentricity are respectively obtained according to the described static eccentricity detection method and inclined eccentricity detection method.

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