A method for identifying a bulging fault of a liquid-immersed AC motor shield sleeve

Abstract

The application discloses a kind of liquid-immersed AC motor shield sleeve bulging fault identification methods, belong to liquid-immersed AC motor technical field.Construct liquid-immersed AC motor electromagnetic network model;Respectively calculate reluctance parameter and inductance parameter;Reluctance parameter and inductance parameter are input into liquid-immersed AC motor electromagnetic network model;Air gap magnetic field distribution function is calculated using liquid-immersed AC motor electromagnetic network model, and shielding sleeve bulging fault information is obtained by analysis.It is simple, easy to use, without sensor, can identify the electromagnetic field strong coupling effect of liquid-immersed motor stator shield sleeve and rotor shield sleeve in narrow space, due to local temperature is too high, pressure distribution is uneven, and causes the bulging fault.

Description

Technical Field

[0001] This invention belongs to the field of liquid-immersed AC motor technology, specifically relating to a method for identifying shield bulging faults in liquid-immersed AC motors. Background Technology

[0002] In liquid-immersed motors, due to the special properties of the liquid medium, the need for high thermal conductivity in the rotor, and the requirement for good mechanical support, the shielding sleeve is made of Hastelloy, a non-magnetic alloy. During motor operation, this alloy is placed in an alternating air gap magnetic field, generating strong eddy currents in the shielding sleeve, leading to significant ohmic losses. When the motor operates for extended periods, the shielding sleeve is constantly exposed to mechanical stress, liquid corrosion, eddy current losses, and high temperatures, making it prone to deformation, bulging, and even cracking. Shielding sleeve bulging is a unique and common fault in liquid-immersed motor systems, with serious consequences: it allows the liquid pumped by the pump to enter the motor, potentially causing system collapse and threatening safe production.

[0003] To enhance the magnetic field strength inside the motor, the shielding sleeve is an ultra-thin-walled component tightly installed within a very narrow air gap, making invasive fault detection via large-scale sensor installation impossible. Therefore, non-invasive, sensorless or minimally sensored status sensing, particularly for identifying the location and extent of shielding sleeve bulge faults, is crucial for the efficient, safe, and stable operation of the system. However, the characteristic signals from bulge faults are not readily apparent, making it difficult to directly apply non-invasive detection methods used in traditional unshielded motors to liquid-immersed motors. Summary of the Invention

[0004] Purpose of the invention: To address the shortcomings of existing technologies, this invention provides a method for identifying shielding sleeve bulge faults in liquid-immersed AC motors. This method rapidly analyzes the harmonic amplitude-frequency characteristics of the motor's air gap magnetic field caused by the shielding sleeve bulge, thereby detecting and identifying potential threats of bulge faults during the operation of liquid-immersed motors without the use of sensors, effectively improving the efficient, long-term, and stable operation of the shielded electric pump system.

[0005] Technical Solution: To achieve the above technical objectives, this invention discloses a method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor, the steps of which are as follows: S1. Construct an electromagnetic network model for a liquid-immersed AC motor; S2. Calculate the reluctance parameters based on the geometric dimensions of the liquid-immersed AC motor and the permeability of the ferromagnetic material. S3. Calculate the inductance parameters based on the electromagnetic field inside the liquid-immersed AC motor obtained from finite element simulation. S4. Input the reluctance and inductance parameters into the electromagnetic network model of the liquid-immersed AC motor. S5. The air gap magnetic field distribution function is calculated using the electromagnetic network model of the liquid-immersed AC motor, and the shielding sleeve bulge fault information is obtained through analysis.

[0006] Furthermore, the calculated reluctance parameters include: stator tooth reluctance. Stator yoke reluctance Rotor tooth magnetic reluctance Rotor yoke reluctance Stator tooth leakage flux and magnetic reluctance Inter-tooth leakage flux and magnetic resistance of rotor Equivalent air gap magnetic reluctance The calculated inductance parameters include: stator shielding sleeve and rotor tooth under-tooth main inductance. Rotor shielding sleeve, rotor teeth under main inductor Stator shielding sleeve, stator slot leakage inductance 1. Rotor shield sleeve, leakage inductance under rotor slot .

[0007] Furthermore, the stator shielding sleeve and the main inductor under the stator teeth The calculation method is as follows: a1. According to The electromagnetic field inside the motor obtained from the finite element simulation at that time was used to extract the main magnetic flux on the stator shield and rotor shield, respectively. and the eddy currents induced by this magnetic flux. , will the main magnetic flux and eddies The distribution in a planar space is denoted as a complex matrix. Complex matrix , superscript " " represents a matrix; a2. Calculate the complex matrix using the following formula. Complex matrix radial component of each element : , , In the formula and Representing a complex matrix Complex matrix The element in the x-th row and y-th column of the array. and These represent the radial components of the element in the x-th row and the y-th column, respectively. , and These represent the cosine values ​​of the horizontal angle between the elements; a3. Traverse the entire planar space The range of values ​​depends on the radial component of the element. and All values ​​are used to construct the main magnetic flux. and eddies radial component matrix and ; a4. Using the formula: Solve for the main magnetic flux Along the straight segment The integral value of the magnetic flux , The value at time is denoted as Use the formula: Solving eddy currents Along the straight segment The integral value of the current , The value at time is denoted as ,in For a line integral of the first kind, In the electromagnetic network model of a liquid-immersed AC motor, the line segments connecting the main magnetic flux between any two stator teeth and rotor teeth coincide on the stator shielding sleeve. Represents the arc length infinitesimal element on the curve; a5, in Repeat steps a1-a4 at time t to obtain the result. The integral value at time t and integral values In the formula Indicates the number of pole pairs of the motor. Indicates the rotor speed; a6. Will Time and The difference between the integral values ​​of the magnetic flux at time t is... ;Will Time and The difference between the integral values ​​of the current at time t is... ; a7. Using formulas The main inductance under the rotor teeth of the stator shield sleeve is obtained by solving. .

[0008] Furthermore, the rotor shield sleeve has a main inductance under the rotor teeth. The calculation method is as follows: The line segment in a4 This is changed to represent the line segment in the electromagnetic network model of a liquid-immersed AC motor where the main magnetic flux connecting each pair of stator and rotor teeth coincides on the rotor shield. , The formula for solving the integral numerically in a4 is rewritten as follows: and , The formula for subtracting integral values ​​in a6 can be rewritten as follows: and , The inductance calculation formula in a7 is rewritten as follows: ; By repeatedly executing a1~a7 using the rewritten formula above, the main inductance under the rotor teeth of the rotor shield can be calculated. .

[0009] Furthermore, the stator shield sleeve has a leakage inductance under the stator slot. The calculation method is as follows: b1, according to The electromagnetic field inside the motor obtained from the finite element simulation at that time was used to extract the leakage flux on the stator shield and rotor shield, respectively. and the eddy currents induced by this magnetic flux. , to leak magnetic flux and eddies The distribution in a planar space is denoted as a complex matrix. Complex matrix ; b2. Calculate the complex matrix using the following formula. Complex matrix radial component of each element : , , In the formula and express and The element in the x-th row and y-th column, and These represent the radial components of the element. , and Representing elements respectively and The cosine of the horizontal angle; b3. Traverse the entire range of values ​​for (x, y) in the planar space, and obtain the elements according to step b2. and All values, construct leakage flux and eddies radial component matrix and ; b4. Using the formula Solve for leakage flux φ σ The integral value along the straight line segment Lsσ , The value at time is denoted as Use formula Solving for eddy current i σ The integral value along the straight line segment Lsσ , The value at time is denoted as ,in In the electromagnetic network model of a liquid-immersed AC motor, the line segments representing leakage flux between any two stator teeth coincide on the stator shielding sleeve. Represents the arc length infinitesimal element on the curve; b5, in Repeatedly execute b1~b4 at time 1 to get the result. The integral value at time t and In the formula Indicates the number of pole pairs of the motor. Indicates the rotor speed; b6, will Time and The difference between the integral values ​​of the leakage flux at time t is: ; Will Time and The difference between the integral values ​​of the current at time t is: ; b7. Using formulas The leakage inductance under the stator slot of the stator shield is obtained by solving the problem. .

[0010] Furthermore, the leakage inductance under the rotor slot of the rotor shielding sleeve The calculation method is as follows: The integral in b4 is along the straight line segment Revised to: In the electromagnetic network model of a liquid-immersed AC motor, the lines connecting each pair of rotor teeth representing leakage flux coincide on the rotor shielding sleeve. , Accordingly, the formula for solving the integral value in b4 is rewritten as follows: and ; The formula for subtracting integral values ​​in b6 can be rewritten as follows: and , The formula for calculating leakage inductance in b7 can be rewritten as follows: ; By re-executing b1~b7 using the rewritten formulas described above, the leakage inductance under the rotor slot of the rotor shield can be calculated. .

[0011] Furthermore, methods for analyzing the degree and location of shielding sleeve bulge failure: The degree of bulging failure refers to the maximum displacement of the arc contour of the shielding sleeve from the non-fault state; the location of bulging failure refers to the bulging of the shielding sleeve at the place where it contacts the stator teeth or rotor teeth, or the bulging of the shielding sleeve at the place where it contacts the stator slot or rotor slot. c1. Analysis method for the degree of tooth bulge failure: determined by the displacement of the stator shielding sleeve bulge based on planar geometric relationships. The value is obtained from the displacement of the rotor shield sleeve protrusion. The numerical value; the degree of tooth bulge failure is expressed using The numerical change is represented, and this change is then mapped to the electromagnetic network model of the liquid-immersed AC motor for solution; specifically, through the formula: , Seek Time and At what time is the main magnetic flux value? and ; Using the formula: ,get Time and The difference in the value of the main magnetic flux at time t ; Through the formula: Seeking Time and The corresponding current value at time t and , Then use the formula: ,get Time and The difference in the corresponding current values ​​at time t ; Using formula ,Will The numerical change is transferred to the change in the main inductance of the stator and rotor shielding sleeves. ; By solving the problem containing The electromagnetic network model of a liquid-immersed AC motor, that is, the sum of the main inductance of the shielding sleeve. Substituting the electromagnetic network model of the liquid-immersed AC motor into the solution, we obtain the air gap magnetic field distribution function with different amplitude and frequency characteristics. We then use Fourier analysis to analyze the air gap magnetic field distribution function and thus determine the degree of tooth bulge fault. c2. Analysis method for the degree of slot bulge fault: The straight segment is obtained from the displacement of the stator shield sleeve based on the plane geometric relationship. The value is obtained from the linear segment of the rotor shield sleeve protrusion displacement. The numerical value; the degree of groove bulge failure is expressed using... The numerical change is represented, and this change is then mapped to the electromagnetic network model of the liquid-immersed AC motor for solution, specifically: Through formula Seeking Time and leakage flux value at time 1 and leakage flux value Then calculate the difference. ; Through formula Seeking Time and The corresponding current value at time t and corresponding current values Then calculate the difference. ; Through the formula: ,Will The change is transferred to the change in leakage inductance of the stator and rotor shielding sleeves. ; By solving for changes The electromagnetic network model of a liquid-immersed AC motor, that is, the sum of the leakage inductance of the shielding sleeve. Substituting the electromagnetic network model of the liquid-immersed AC motor, we obtain the air gap magnetic field distribution function with different amplitude and frequency characteristics. We then use Fourier analysis to analyze the air gap magnetic field distribution function and thus determine the degree of slot bulging fault. c3. Determine the location of the bulge fault based on the severity of tooth bulge and slot bulge faults: Based on the calculation results in c2, determine the change in the main inductance of the stator and rotor shielding sleeves. Or changes in leakage inductance Substituting the electromagnetic network model of the liquid-immersed AC motor into the solution, we obtain the air gap magnetic field distribution function with different amplitude and frequency characteristics, and then obtain the fault location through Fourier analysis.

[0012] Furthermore, the electromagnetic influence of the shielding sleeve was analyzed using the following method: d1. Given the conductivity of the shielding sleeve material, obtain the air gap magnetic field distribution function containing the shielding sleeve by executing S3~S5; d2. Set the conductivity of the shielding sleeve material to that of air, and obtain the air gap magnetic field distribution function without the shielding sleeve by executing S3~S5; d3. By comparing and analyzing the air gap magnetic field distribution function with and without the shielding sleeve, the electromagnetic influence of the shielding sleeve can be obtained through Fourier analysis.

[0013] A computer device includes a processor and a memory, the processor being electrically connected to the memory, the memory being used to store instructions and data, and the processor being used to execute a method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor.

[0014] Beneficial effects: This invention can quickly analyze the harmonic amplitude-frequency characteristics of the air gap magnetic field caused by shield bulging in motors without the need for sensors. By analyzing the harmonic characteristics of the air gap electromagnetic field caused by shield bulging faults, it can quickly identify the minute deformations of the shield and their locations. It solves the problem that traditional invasive detection methods are difficult to install sensors on a large scale on the shield for direct measurement, and it also solves the problem that non-invasive signal detection methods used on conventional unshielded motors cannot be directly applied to liquid-immersed motors due to the unclear output characteristics of bulging faults. This invention provides a non-invasive detection solution for shield bulging faults, a unique, common, and important fault type in liquid-immersed motors. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the electromagnetic network model of the liquid-immersed AC motor in an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the first type of curve integration path of the electromagnetic network model of the liquid-immersed AC motor in an embodiment of the present invention. In the figure, (a) is a schematic diagram of the main inductance calculation; (b) is a schematic diagram of the leakage inductance calculation.

[0017] Figure 3 This is a schematic diagram of the magnetic circuit saturation query of the electromagnetic network model of the liquid-immersed AC motor in an embodiment of the present invention. In the figure, (a) is a schematic diagram when the stator teeth and rotor teeth have no overlap; (b) is a schematic diagram when the stator teeth and rotor teeth have overlap.

[0018] Figure 4 The diagram shows a shielding sleeve bulge fault in an embodiment of the present invention. In the diagram, (a) is a schematic diagram of rotor sleeve tooth bulge; (b) is a schematic diagram of rotor sleeve groove bulge; (c) is a schematic diagram of stator sleeve tooth bulge; and (d) is a schematic diagram of stator sleeve groove bulge.

[0019] Figure 5 This is a computer simulation diagram of the electromagnetic network model of the liquid-immersed AC motor in the implementation of this invention.

[0020] Figure 6 This is a schematic diagram of the air gap magnetic field distribution function and harmonic decomposition under the condition of no bulging fault in the embodiment of the present invention.

[0021] Figure 7 This is a schematic diagram of the air gap magnetic field distribution function under a typical bulge fault in an embodiment of the present invention.

[0022] Figure 8This is a schematic diagram of harmonic analysis of the air gap magnetic field distribution function under a typical bulge fault in an embodiment of the present invention.

[0023] Figure 9 This is a schematic diagram comparing the air gap magnetic field distribution function of motors with and without shielding sleeves in the embodiments of the present invention.

[0024] Figure 10 This is a schematic diagram of harmonic analysis of the air gap magnetic field distribution function of motors with and without shielding sleeves in an embodiment of the present invention. Detailed Implementation

[0025] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0026] This invention discloses a method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor. By calculating and analyzing the air gap magnetic field, the location and extent of the bulging fault can be identified. Specifically, it includes: 1) establishing shielding sleeve parameters during normal operation; 2) establishing shielding sleeve parameters during fault operation; and 3) analyzing the fault and the electromagnetic influence of the shielding sleeve.

[0027] like Figure 1 As shown, the constructed electromagnetic network model of the liquid-immersed AC motor can be divided into three parts from top to bottom: stator, air gap, and rotor. The stator includes a magnetomotive force (M), representing the magnetomotive force generated after current is applied to the stator windings; this is the source of magnetic flux driving the magnetic circuit. It also includes a magnetic saturation lookup table (K), labeled above the stator teeth and accompanied by a 3D surface plot. The stator section includes alternating stator slots and stator teeth; the model uses nodes to realize the convergence and branching of magnetic flux paths. The air gap includes a stator shielding sleeve separating the stator and a rotor shielding sleeve separating the rotor. The rotor includes alternating rotor teeth and rotor slots.

[0028] The stator teeth are connected to the adjacent rotor teeth on the left and right sides respectively, and an equivalent air gap reluctance is connected in series on each connection line. Stator shielding sleeve rotor teeth under main inductance and rotor shielding sleeve rotor teeth under main inductance The stator teeth are connected to the adjacent stator teeth on the left and right, and the leakage inductance under the stator slot of the stator shield is connected in series on each connection. and stator tooth leakage flux and magnetic reluctance The rotor teeth are connected to the adjacent rotor teeth on the left and right sides respectively, and the leakage inductance under the rotor slot of the rotor shield is connected in series on each line. and rotor tooth leakage flux and magnetic resistance .

[0029] Calculate magnetoresistance parameters: including Figure 1 The equivalent air gap magnetoresistance in Stator tooth reluctance Stator yoke reluctance Rotor tooth magnetic reluctance Rotor yoke reluctance Stator tooth leakage flux and magnetic reluctance Inter-tooth leakage flux and magnetic resistance of rotor These calculations are based on the motor's geometry and use formulas. Obtain, among which This represents the resistance value of the corresponding magnetic reluctance. The length of the magnetic reluctance, Let be the permeability of the ferromagnetic material under ideal conditions. The width of the magnetic reluctance.

[0030] Calculate inductance parameters: including Figure 1 The stator shield sleeve rotor tooth under main inductor and rotor shielding sleeve rotor teeth under main inductor The steps are as follows: a1, based on The electromagnetic field inside the motor obtained from the finite element simulation at that time was used to extract the main magnetic flux on the stator shielding sleeve. and the eddy currents induced by this magnetic flux. , will the main magnetic flux and eddies The distribution in a planar space is denoted as a complex matrix. Complex matrix , superscript " " represents a matrix; a2. Calculate complex matrices Complex matrix The radial component r of each element is expressed as follows: , In the formula and Representing a complex matrix Complex matrix The element in the x-th row and y-th column, and These represent the radial components of the element. cosα φ(x,y) and cosα i(x,y) These represent the cosine values ​​of the horizontal angle between the elements; a3. Traverse the range of values ​​for (x, y) in the planar space, and obtain the result from step a2. and All values ​​are used to construct the main magnetic flux. and eddies radial component matrix and ; a4. Using the formula: and Solve for the integral values ​​of parameters φ and i along the line segment Ls, respectively. and In the formula ∫ Ls For a line integral of the first kind, In the electromagnetic network model of a liquid-immersed AC motor, the line segments connecting the main magnetic flux between each pair of stator and rotor teeth coincide on the stator shielding sleeve, i.e., along... Figure 2 The line connecting points A and B shown in (a) express Arc length infinitesimal element; a5, in Repeat steps a1 to a4 at time t, and obtain the result at time t. Values ​​at any given time and In the formula Indicates the number of pole pairs of the motor. Indicates the rotor speed; a6. Will Time and At present Do the work, record it as ;Will Time and At present Do the work, record it as ; a7. Using formulas The main inductance under the rotor teeth of the stator shield sleeve is obtained by solving. ; a8. Rotor shielding sleeve, rotor tooth under-rotor main inductance Calculation method: Repeat steps a1 to a7, the only difference being in a4. Transformed into a line segment representing the main magnetic flux connection between any two stator teeth and rotor teeth in the network model coinciding on the rotor shielding sleeve. Accordingly, the formula in a4 is changed to and Rewrite the formula in a7 as follows: .

[0031] Leakage inductance calculation: including Figure 1 The stator shield sleeve and stator slot leakage inductance described in the article and the leakage inductance under the rotor slot of the rotor shielding sleeve The steps are as follows: b1. According to a certain The electromagnetic field inside the motor obtained from the finite element simulation at that time was used to extract the leakage flux on the stator shielding sleeve. and the eddy currents induced by this magnetic flux. , parameters and The distribution in a planar space is denoted as a complex matrix. Complex matrix ; b2. Calculate the complex matrix Complex matrix radial component of each element The mathematical expression is , In the formula and express and The element in the x-th row and y-th column, and These represent the radial components of the element. , and Representing elements respectively and The cosine of the horizontal angle; b3. Traverse the entire range of values ​​(x, y) in the planar space, and obtain the elements according to step b2. and All values, construct leakage flux and eddies radial component matrix and ; b4. Using the formula Solve for leakage flux φ σ The integral value along the straight line segment Lsσ , The value at time t is denoted as Use formula Solving for eddy current i σ The integral value along the straight line segment Lsσ , The value at time is denoted as ,in In the electromagnetic network model of a liquid-immersed AC motor, the line segments representing leakage flux between any two stator teeth coincide on the stator shielding sleeve. Represents the arc length infinitesimal element on the curve; b5, in Repeatedly execute b1~b4 at time 1 to get the result. The integral value at time t and In the formula Indicates the number of pole pairs of the motor. This indicates the rotor speed; " / " represents the division operator. b6, will Time and The difference between the integral values ​​of the leakage flux at time t is: ; Will Time and The difference between the integral values ​​of the current at time t is: ; b7. Using the formula The leakage inductance under the stator slot of the stator shield is obtained by solving the problem. .

[0032] b8. Rotor shield sleeve, leakage inductance L under rotor slot RCσ The calculation method is as follows: Repeat steps b1 to b7, with the only difference being that in b4, Lsσ is replaced by Lrσ, which represents the line segment Lrσ on the rotor shielding sleeve that coincides with the line connecting each pair of rotor teeth representing leakage flux in the network model. Accordingly, the formula in b4 is changed to... and The formula for the difference of integral values ​​in b6 can be rewritten as follows: and The formula for calculating leakage inductance in b7 can be rewritten as follows: ; Establishing the magnetic saturation lookup table K: ① Connect the magnetic reluctances of each component in series and sum them to form a magnetic circuit. Based on the given value of the magnetomotive force, use Ohm's law for the magnetic circuit. Calculate the performance of each component of the motor under different rotor position conditions. Establish the ideal magnetic flux of the main magnetic circuit under different winding excitation intensities and stator and rotor positions. In the formula This is a given value for the magnetomotive force of the winding under different excitation intensities. The reluctance of each component of the motor (including stator tooth reluctance, stator yoke reluctance, rotor tooth reluctance, rotor yoke reluctance, and equivalent air gap reluctance) is calculated using the following formula: ,in The length of the corresponding magnetic reluctance, Let be the cross-sectional area of ​​the magnetic reluctance. Permeability, permeability of the air gap It is a constant. Setting up ideal ferromagnetic materials , ① To establish the summation symbol; ② To establish the actual magnetic flux of the main magnetic circuit under different winding excitation intensities and rotor positions. Given the magnetization curve of a ferromagnetic material, calculate iteratively according to ① to make Gradually approaching the true value Obtaining the actual magnetic flux ③ According to the formula The equivalent resistance value of the magnetic reluctance generated by the magnetic saturation of the ferromagnetic material is calculated to obtain the values ​​under different winding excitation intensities and stator and rotor position combinations. The query table is constructed, and its structure and form are as follows: Figure 3 As shown.

[0033] Parameterization of the degree and location of shielding sleeve bulge faults: The degree of bulge fault refers to the maximum displacement of the outline (represented by an arc) of the shielding sleeve protrusion or depression from the non-fault state. The location of the bulge fault refers to whether the sub-shield sleeve shows a protrusion (tooth bulge) at the contact point with the stator or rotor teeth, or a depression (slot bulge) at the contact point with the stator or rotor slots. Figure 4 As shown. The line segments on the stator shielding sleeve where the main magnetic flux connecting each pair of stator and rotor teeth coincide. The line segments on the rotor shielding sleeve that coincide with the main magnetic flux connecting each pair of stator teeth and rotor teeth. The line segments on the stator shielding sleeve that coincide with the main magnetic flux connecting each pair of stator teeth. In this network model, the line segments connecting the main magnetic flux between any two rotor teeth coincide on the rotor shielding sleeve. The parameters are divided into the following three steps: Step 1, Parametric method for determining the degree of tooth bulge fault: Determined by the displacement of the stator shielding protrusion based on planar geometric relationships. The value is obtained from the displacement of the rotor shield sleeve protrusion. The numerical value. The degree of tooth bulge failure is expressed using... The numerical changes are represented, and then expressed through the formulas on the stator shielding sleeve and the rotor shielding sleeve. The numerical change is linearly mapped to the sum of the main inductance under the stator teeth of the stator shield and the main inductance under the rotor teeth of the rotor shield. The numerical change. When a fault occurs, the bulge of the stator shield in the tooth bulge area directly affects... The length of the arc, the displacement of the vertex and The length variation shows a linear relationship; the bulge of the rotor shield sleeve within the tooth bulge area directly affects the length of Lr, and the displacement of the arc apex is related to... The length changes are linearly related. Since the magnetic field in the convex region has a similar distribution to the original magnetic field, based on the linear property of the first kind of line integral, the main inductance... The value of its integral line There is a linear relationship between the lengths of the main inductor and the main inductor. The value of its integral line There is a linear relationship between their lengths. Furthermore, based on the linear property of line integrals, The value as The numerical changes show a linear relationship between the two. The degree of failure is represented by the independent variable. Changes in numerical values ​​represent, and are thus reflected in, variables. Regarding the numerical changes, by solving for the values ​​containing The model yields air gap magnetic field distribution functions with different amplitude-frequency characteristics, and the degree of fault is analyzed by post-processing (Fourier analysis) of the function.

[0034] Step 2, Parametric method for determining the degree of slot bulge fault: The degree is determined by the displacement of the stator shielding sleeve recess based on planar geometric relationships. The value is obtained from the displacement of the rotor shield sleeve protrusion. The numerical value. The severity of the groove bulge failure is expressed using... The numerical changes are represented, and then expressed through the formulas on the stator shielding sleeve and the rotor shielding sleeve. The numerical change is linearly mapped to the sum of the stator shielding sleeve stator tooth leakage inductance and the rotor shielding sleeve rotor tooth leakage inductance. The numerical change. When a fault occurs, the indentation of the stator shield sleeve in the slot bulge area directly affects... The length of the arc, the displacement of the vertex and The length variation shows a linear relationship; the indentation of the rotor shield sleeve within the slot bulge area directly affects... The length of the arc, the displacement of the vertex and The length changes are linearly related. Since the magnetic field in the concave region has approximately the same spatial distribution as the original magnetic field, based on the linearity of the first kind of line integral, the leakage inductance... The value of its integral line There is a linear relationship between the lengths; leakage inductance The value of its integral line There is a linear relationship between their lengths. Furthermore, based on the linear property of line integrals, The value as The numerical changes show a linear relationship between the two. The degree of failure is represented by the independent variable. Changes in numerical values ​​represent, and are thus reflected in, variables. Regarding the numerical changes, by solving for the values ​​containing The model yields air gap magnetic field distribution functions with different amplitude-frequency characteristics, and the degree of fault is analyzed by post-processing (Fourier analysis) of the function.

[0035] Step 3: Combining the above two steps, the location of the shielding sleeve bulge fault can be parameterized: the sum of the main inductance before and after the fault. The value or leakage inductance The changes in the sum of values ​​are substituted into the model for solution to obtain air gap magnetic field distribution functions with different amplitude and frequency characteristics. Then, the location of the fault is analyzed by post-processing (Fourier analysis) of the function.

[0036] Construction and operation of the electromagnetic network model of a liquid-immersed AC motor: After inputting the geometric and simulation settings parameters of the motor, the parameters are first processed in a Matlab m-file, and then the software FEMM (Finite Element Method Magnetics) is called to perform finite element calculations. and The electromagnetic field at a given time is stored in matrix form on the Matlab simulation platform. Figure 5 The diagram shows the distribution of the motor's magnetic field as magnetic field lines. Based on the above parameters, an electromagnetic network model of the liquid-immersed AC motor is established: ① Calculate the stator tooth reluctance. Stator yoke reluctance Rotor tooth magnetic reluctance Rotor yoke reluctance Stator tooth leakage flux and magnetic reluctance Inter-tooth leakage flux and magnetic resistance of rotor Equivalent air gap magnetic reluctance Then substitute them into the model; ② Establish the magnetomotive force based on the excitation current and winding parameters. That is, magnetomotive force function , For winding functions, Both are phase currents, and are given by measurement. Indicates the rotor position. Indicates time; ③ Calculates the main inductance under the rotor teeth of the stator shielding sleeve based on the electromagnetic field obtained from finite element simulation. Rotor shielding sleeve, rotor teeth under main inductor Stator shielding sleeve, stator slot leakage inductance 1. Rotor shield sleeve, leakage inductance under rotor slot Then substitute the values ​​into the model; ④ Establish a magnetic saturation lookup table K based on the magnetization curve of the ferromagnetic material; ⑤ Obtain the corresponding magnetic reluctance value through the lookup table K based on the rotor position and phase current value. Then Replace with After completing the above five steps, run the electromagnetic network model of the liquid-immersed AC motor and obtain the air gap magnetic field distribution function according to Ohm's law for magnetic circuits.

[0037] Analysis of the air gap magnetic field distribution function under no bulge fault: such as Figure 6As shown, the horizontal axis represents the circumferential mechanical angles from 0° to 180°, covering the entire distribution period of the air gap magnetic field, while the vertical axis represents the numerical value and direction of the magnetic flux density. The air gap magnetic field distribution function is the distribution of the magnetic field within the motor's air gap along the circumferential direction. It is a core element of the electromagnetic analysis and optimization of the motor body, representing the magnetic flux density distribution of the electromagnetic field under the stator and rotor teeth and slots throughout the entire circumference. Further Fourier decomposition of this function yields sinusoidal components with different odd frequencies, including the first fundamental frequency and the third, fifth, and seventh high-frequency harmonic components.

[0038] Analyze the air gap magnetic field distribution function under bulging faults: Substitute the following values ​​representing different bulging fault locations and degrees—slot bulge 0.1mm, slot bulge 0.5mm, tooth bulge 0.1mm, and tooth bulge 0.5mm—into "Model Construction and Run" ③ to calculate the corresponding main inductance and leakage inductance. Then, re-execute ③~⑤ to calculate the corresponding air gap magnetic field distribution function. For example... Figure 7 As shown: the horizontal axis represents the circumferential direction from 0 to 180. o From a mechanical perspective, this study covers the entire distribution period of the air gap magnetic field. The vertical axis represents the value and direction of the magnetic flux density, and the four curves represent the air gap magnetic field distribution function under different locations and degrees of fault. The calculation results show that: ① The overall distribution of the function is consistent under different faults, exhibiting a sinusoidal distribution with local fluctuations of different shapes; ② The local fluctuations of the curve under slot bulge faults are relatively small; ③ The local fluctuations of the curve under tooth bulge faults are relatively large, and the changes are more obvious as the degree of fault increases.

[0039] Harmonic characteristic analysis of the air gap magnetic field distribution function: such as Figure 8 As shown, four colors are used to correspond to Figure 7 The air gap magnetic field distribution function in the figure represents the amplitude and frequency characteristics of the fundamental and harmonic waves under different fault locations and degrees. The horizontal axis represents the frequency order, and the vertical axis represents the amplitude (expressed as a percentage). The first-order wave is the working fundamental wave, which forms the basic shape of the curve and is responsible for the electromechanical energy conversion of the main magnetic field inside the motor. The other higher-order waves (3rd, 5th, and 7th) are harmonics, which cause local magnetic field oscillations inside the motor, resulting in iron loss and noise during motor operation. It can be seen that: ① The location and degree of the fault do not affect the working fundamental wave, making it difficult to determine whether a fault has occurred based on the input and output performance of the motor during operation; ② The amplitude changes of harmonics are relatively small under slot bulging faults: the 3rd harmonic remains unchanged, while the 5th and 7th harmonics decrease slightly. This is because the degree of slot bulging is affected by leakage inductance. and The value of the leakage inductance is determined by the change in the value of the leakage flux, and since the leakage flux has little effect on the electromagnetic field of the motor, the change in the value of the leakage inductance has little effect on the air gap magnetic field distribution function; ③ The harmonic amplitude changes significantly under tooth bulge faults: the 3rd harmonic decreases to a certain extent, and the 5th and 7th harmonics decrease more significantly. This is because the bulge area directly increases the air gap magnetic field distribution function. The value of , thus increasing The value. Due to Located on the line connecting the main magnetic flux, the main magnetic flux has a significant impact on the electromagnetic field of the motor, therefore The increase of has a significant impact on the air gap magnetic field distribution function, and it significantly suppresses the amplitude of the main harmonics.

[0040] Based on the above analysis, the methods for determining the location and extent of bulging faults in liquid-immersed motors are as follows: ① When the amplitude of the 3rd harmonic remains unchanged, and the amplitudes of the 5th and 7th harmonics decrease slightly, it is a slot bulge, and there is a relatively obvious linear relationship between the degree of bulging and the degree of amplitude reduction; ② When the amplitude of the 3rd harmonic decreases to a certain extent, it is a tooth bulge, at which point the amplitudes of the 5th and 7th harmonics decrease significantly, and there is a relatively obvious linear relationship between the degree of bulging and the degree of amplitude reduction.

[0041] Analysis of the electromagnetic influence of the shielding sleeve: The main inductance under the rotor teeth of the shielding sleeve in this model... Rotor shielding sleeve, rotor teeth under main inductor Stator shielding sleeve, stator slot leakage inductance 1. Rotor shield sleeve, leakage inductance under rotor slot When the value is set to 0, the shielding material becomes air, and the liquid-immersed motor becomes a regular motor without a shield. The model is then used again for calculations, and the electromagnetic influence of the shielding is analyzed by comparing the amplitude and frequency characteristics of the fundamental and harmonic waves of the air gap magnetic field with and without a shield. For example... Figure 9 As shown, the horizontal axis represents the circumferential mechanical angles from 0° to 180°, covering the entire distribution period of the air gap magnetic field, while the vertical axis represents the value and direction of the magnetic flux density. Figure 9 As can be seen, the liquid-immersed motor shielding sleeve makes the overall change in the air gap magnetic flux density distribution smoother, and the local fluctuations more moderate. Further Fourier decomposition yields the amplitude and frequency characteristics of the fundamental and harmonic waves of the air gap magnetic field, such as... Figure 10 The curve distribution for the liquid-immersed motor with a shielding sleeve is observed as follows: ① The amplitude of the 3rd harmonic decreases the most, making the overall curve smoother; ② The amplitude of the 7th harmonic increases the most, resulting in higher local fluctuation frequencies in the curve. This analysis demonstrates that the proposed electromagnetic network model can compare and analyze the electromagnetic effects of the shielding sleeve: when the shielding sleeve is present, the main inductance under the rotor teeth of the stator shielding sleeve... and rotor shielding sleeve rotor teeth under main inductance L RCIt can suppress the main third electromagnetic harmonics, making the air gap magnetic field distribution function curve smoother, resulting in less output torque pulsation and smoother motor operation.

[0042] The above description is merely one embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiment based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor, characterized in that, The steps are as follows: S1. Construct an electromagnetic network model for a liquid-immersed AC motor; S2. Calculate the reluctance parameters based on the geometric dimensions of the liquid-immersed AC motor and the permeability of the ferromagnetic material. S3. Calculate the inductance parameters based on the electromagnetic field inside the liquid-immersed AC motor obtained from finite element simulation. S4. Input the reluctance and inductance parameters into the electromagnetic network model of the liquid-immersed AC motor. S5. The air gap magnetic field distribution function is calculated using the electromagnetic network model of the liquid-immersed AC motor, and the shielding sleeve bulge fault information is obtained through analysis. The degree of bulging fault refers to the maximum displacement of the arc contour of the shielding sleeve from the non-fault state; the location of bulging fault refers to the bulging of the shielding sleeve at the contact point with the stator teeth or rotor teeth, or the bulging of the shielding sleeve at the contact point with the stator slots or rotor slots. set up In the electromagnetic network model of a liquid-immersed AC motor, the line segments connecting the main magnetic flux between any two stator teeth and rotor teeth coincide on the stator shielding sleeve; assuming In the electromagnetic network model of a liquid-immersed AC motor, the line segments connecting the main magnetic flux between each pair of stator teeth and rotor teeth coincide on the rotor shielding sleeve. Analysis method for the degree of tooth bulge failure: determined by the displacement of the stator shielding sleeve bulge based on planar geometric relationships. The value is obtained from the displacement of the rotor shield sleeve protrusion. The numerical value; the degree of tooth bulge failure is expressed using The numerical change is represented, and then this change is mapped to the electromagnetic network model of the liquid-immersed AC motor for solution. Determine the location of the bulge fault by assessing the severity of tooth bulge and slot bulge faults: This involves analyzing the changes in the main inductance of the stator and rotor shielding sleeves. Or changes in leakage inductance Substituting the electromagnetic network model of the liquid-immersed AC motor into the solution, we obtain the air gap magnetic field distribution function with different amplitude and frequency characteristics, and then obtain the fault location through Fourier analysis.

2. The method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor according to claim 1, characterized in that, The calculated reluctance parameters include: stator tooth reluctance. Stator yoke reluctance Rotor tooth magnetic reluctance Rotor yoke reluctance Stator tooth leakage flux and magnetic reluctance Inter-tooth leakage flux and magnetic resistance of rotor Equivalent air gap magnetic reluctance The calculated inductance parameters include: stator shielding sleeve and rotor tooth under-tooth main inductance. Rotor shielding sleeve, rotor teeth under main inductor Stator shielding sleeve, stator slot leakage inductance 1. Rotor shield sleeve, leakage inductance under rotor slot .

3. The method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor according to claim 2, characterized in that, Stator shielding sleeve stator teeth under main inductor The calculation method is as follows: a1. According to The electromagnetic field inside the motor obtained from the finite element simulation at that time was used to extract the main magnetic flux on the stator shield and rotor shield, respectively. and the eddy currents induced by this magnetic flux. , will the main magnetic flux and eddies The distribution in a planar space is denoted as a complex matrix. Complex matrix , superscript " represents a matrix; a2. Calculate the complex matrix using the following formula. Complex matrix radial component of each element : ， ， In the formula and Representing a complex matrix Complex matrix The element in the x-th row and y-th column of the array. and These represent the radial components of the element in the x-th row and the y-th column, respectively. , and These represent the cosine values ​​of the horizontal angle between the elements; a3. Traverse the entire planar space The range of values ​​depends on the radial component of the element. and All values ​​are used to construct the main magnetic flux. and eddies radial component matrix and ; a4. Using the formula: Solve for the main magnetic flux Along the straight segment The integral value of the magnetic flux , The value at time is denoted as Use the formula: Solving eddy currents Along the straight segment The integral value of the current , The value at time is denoted as ,in For a line integral of the first kind, Represents the arc length infinitesimal element on the curve; a5, in Repeat steps a1-a4 at time t to obtain the result. The integral value at time t and integral values In the formula Indicates the number of pole pairs of the motor. This indicates the rotor speed; " / " represents the division operator. a6. Will Time and The difference between the integral values ​​of the magnetic flux at time t is... ;Will Time and The difference between the integral values ​​of the current at time t is... ; a7. Using formulas The main inductance under the rotor teeth of the stator shield sleeve is obtained by solving. .

4. The method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor according to claim 3, characterized in that, Rotor shielding sleeve rotor teeth under main inductance The calculation method is as follows: The line segment in a4 This is changed to represent the line segment in the electromagnetic network model of a liquid-immersed AC motor where the main magnetic flux connecting each pair of stator and rotor teeth coincides on the rotor shield. , The formula for solving the integral numerically in a4 is rewritten as follows: and , The formula for subtracting integral values ​​in a6 can be rewritten as follows: and , The inductance calculation formula in a7 is rewritten as follows: ; By repeatedly executing a1~a7 using the rewritten formula above, the main inductance under the rotor teeth of the rotor shield can be calculated. .

5. The method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor according to claim 4, characterized in that, Stator shielding sleeve under stator slot leakage inductance The calculation method is as follows: b1, according to The electromagnetic field inside the motor obtained from the finite element simulation at that time was used to extract the leakage flux on the stator shield and rotor shield, respectively. and the eddy currents induced by this magnetic flux. , to leak magnetic flux and eddies The distribution in a planar space is denoted as a complex matrix. Complex matrix ; b2. Calculate the complex matrix using the following formula. Complex matrix radial component of each element : ， ， In the formula and express and The element in the x-th row and y-th column, and These represent the radial components of the element. , and Representing elements respectively and The cosine of the horizontal angle; b3. Traverse the entire range of values ​​for (x, y) in the planar space, and obtain the elements according to step b2. and All values, construct leakage flux and eddies radial component matrix and ; b4. Using the formula Solve for leakage flux φ σ The integral value along the straight line segment Lsσ , The value at time is denoted as Use formula Solving for eddy current i σ The integral value along the straight line segment Lsσ , The value at time is denoted as ,in In the electromagnetic network model of a liquid-immersed AC motor, the line segments representing leakage flux between any two stator teeth coincide on the stator shielding sleeve. Represents the arc length infinitesimal element on the curve; b5, in Repeatedly execute b1~b4 at time 1 to get the result. The integral value at time t and In the formula Indicates the number of pole pairs of the motor. Indicates the rotor speed; b6, will Time and The difference between the integral values ​​of the leakage flux at time t is: ； Will Time and The difference between the integral values ​​of the current at time t is: ； b7. Using formulas The leakage inductance under the stator slot of the stator shield is obtained by solving the problem. .

6. The method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor according to claim 5, characterized in that, Rotor shield sleeve, rotor slot leakage inductance The calculation method is as follows: The integral in b4 is along the straight line segment Revised to: In the electromagnetic network model of a liquid-immersed AC motor, the straight line segments on the rotor shielding sleeve that connect the leakage flux between each pair of rotor teeth coincide. , Accordingly, the formula for solving the integral value in b4 is rewritten as follows: and ; The formula for subtracting integral values ​​in b6 can be rewritten as follows: and , The formula for calculating leakage inductance in b7 can be rewritten as follows: ; By re-executing b1~b7 using the rewritten formulas described above, the leakage inductance under the rotor slot of the rotor shield can be calculated. .

7. The method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor according to claim 6, characterized in that, Methods for analyzing the degree and location of shielding sleeve bulges: c1. Analysis method for the degree of tooth bulge failure, specifically through the formula: ， Seeking Time and At what time is the main magnetic flux value? and ; Using the formula: ,get Time and The difference in the value of the main magnetic flux at time t ; Through the formula: Seeking Time and The corresponding current value at time t and , Then use the formula: ,get Time and The difference in the corresponding current values ​​at time t ; Using formula ,Will The numerical change is transferred to the change in the main inductance of the stator and rotor shielding sleeves. ; By solving the problem containing The electromagnetic network model of a liquid-immersed AC motor, that is, the sum of the main inductance of the shielding sleeve. Substituting the electromagnetic network model of the liquid-immersed AC motor into the solution, we obtain the air gap magnetic field distribution function with different amplitude and frequency characteristics. We then use Fourier analysis to analyze the air gap magnetic field distribution function and thus determine the degree of tooth bulge fault. c2. Analysis method for the degree of slot bulge fault: The straight segment is obtained from the displacement of the stator shield sleeve based on the plane geometric relationship. The value is obtained from the linear segment of the rotor shield sleeve protrusion displacement. The numerical value; the degree of groove bulge failure is expressed using... The numerical change is represented, and this change is then mapped to the electromagnetic network model of the liquid-immersed AC motor for solution, specifically: Through formula Seeking Time and leakage flux value at time 1 and leakage flux value Then calculate the difference. ; Through formula Seeking Time and The corresponding current value at time t and corresponding current values Then calculate the difference. ; Through the formula: ,Will The change is transferred to the change in leakage inductance of the stator and rotor shielding sleeves. ; By solving for changes The electromagnetic network model of a liquid-immersed AC motor, that is, the sum of the leakage inductance of the shielding sleeve. Substituting the electromagnetic network model of the liquid-immersed AC motor, we obtain the air gap magnetic field distribution function with different amplitude and frequency characteristics. We then use Fourier analysis to analyze the air gap magnetic field distribution function and thus determine the degree of slot bulging fault. c3. Determine the location of the bulge fault by assessing the severity of the tooth bulge and the groove bulge.

8. The method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor according to claim 1, characterized in that, The method for analyzing the electromagnetic influence of the shielding sleeve is as follows: d1. Given the conductivity of the shielding sleeve material, obtain the air gap magnetic field distribution function containing the shielding sleeve by executing S3~S5; d2. Set the conductivity of the shielding sleeve material to that of air, and obtain the air gap magnetic field distribution function without the shielding sleeve by executing S3~S5; d3. By comparing and analyzing the air gap magnetic field distribution function with and without the shielding sleeve, the electromagnetic influence of the shielding sleeve can be obtained through Fourier analysis.

9. A computer device, characterized in that, It includes a processor and a memory, the processor being electrically connected to the memory, the memory being used to store instructions and data, and the processor being used to execute the method for identifying bulging faults in the shielding sleeve of a liquid-immersed AC motor as described in any one of claims 1-8.

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