Motor rotor loss detection device

Abstract

The invention discloses a motor rotor loss detection device, and relates to the technical field of compressor detection, in particular to a compressor motor rotor loss detection device. According to the invention, the two stators are adopted for excitation in opposite directions, and the stray loss of the rotor is detected and judged according to the size of a power value detected by the detection coil; the base is of a circular groove structure; a shaft is vertically assembled in the center of the base through a bushing and a limiting spring; a sheath is assembled on the upper part of the circumferential table of the base; the top and the bottom of the sheath are each provided with a set of stator, and the stators are packaged through an upper cover plate, a lower cover plate and bolts. The stator is electrically connected with the detection circuit; and a tested rotor is sleeved on the shaft. According to the technical scheme, the problems that in the prior art, an open transformer detection method cannot judge groove breakage, tail end circular ring perforation, poor bevel angle, poor stray loss and the like, and a rotor induced potential oscilloscope test method cannot detect and judge stray loss are solved.

Description

Technical Field

[0001] The invention discloses a motor rotor loss detection device, which relates to the technical field of compressor detection, and in particular to a motor rotor loss detection device for a compressor. Background Art

[0002] With the improvement of motor manufacturing technology, the detection level of motors has also been improved accordingly. As the core component of asynchronous motors, the quality detection of cage cast aluminum rotors has also attracted more and more attention. The quality of cage cast aluminum rotors will directly affect the operating performance of asynchronous motors. Defects in cast aluminum quality will lead to high motor temperature, low efficiency and high noise.

[0003] When the rotor core punching sheets have corrugations, rust spots, oil stains, dust or burrs, poor insulation occurs between the rotor bars and the core, leakage current losses occur between the welding sheets, or high-frequency losses occur in the rotor core. These losses are collectively referred to as stray losses.

[0004] Stray losses will increase the rotor's excitation current and iron loss, reduce the motor's maximum torque, and reduce the motor's efficiency and power factor.

[0005] There are two commonly used methods for testing the performance of cage cast aluminum rotors:

[0006] (1) The open transformer method uses a V-shaped open transformer as the primary and the rotor as the secondary. The rotor to be tested is rotated slowly above the open transformer, and the quality of the rotor can be judged by observing the changes in the primary coil ammeter reading.

[0007] The disadvantage of this method is that it only uses one value to evaluate the rotor. Problems such as broken slots, perforated end rings, poor bevel angles, or poor stray losses cannot be determined by this method alone.

[0008] (2) Rotor induced potential oscilloscope test method: The rotor rotates at a constant angular velocity in the magnetic field generated by the magnet. As the magnetic field cuts the rotor bars, an induced potential is generated in the rotor bars, causing an induced current to flow through the rotor bars. The induced current in the rotor bars will generate a magnetic field in the rotor, and in turn cause a change in the magnetic flux in the voltage detection coil. As a result, the voltage detection coil generates an induced potential, and the induced potential waveform of the coil is displayed through an oscilloscope. When the ideal rotor has no faults, the rotor is symmetrical, and each bar will induce a sine wave with similar amplitude and the same frequency; when the bar has pores or broken grooves, or the end ring is cracked, the frequency and amplitude of the induced potential waveform will change. However, this device has a single function and can only detect the quality of the cast aluminum bars of the rotor, and cannot detect and determine stray losses.

[0009] In view of the problems existing in the above-mentioned prior art, it is very necessary to study and design a new type of motor rotor loss detection device to overcome the problems existing in the prior art. Summary of the invention

[0010] According to the above-mentioned prior art, the open transformer detection method cannot determine the problems of broken slots, end ring perforation, bad bevel and bad stray loss, and the rotor induced potential oscilloscope test method cannot detect and determine the stray loss. A motor rotor loss detection device is provided. The present invention mainly adopts the reverse excitation magnetic field technology, and the size of the power value detected by the voltage detection coil can detect the size of the rotor stray loss, and then screen out defective products.

[0011] The technical means adopted by the present invention are as follows:

[0012] A motor rotor loss detection device uses two stators to excite in opposite directions respectively, and detects and determines the rotor stray loss by detecting the power value detected by the detection coil;

[0013] Further, the motor rotor loss detection device comprises: a rotor to be measured, a shaft, an upper cover plate, bolts, a sleeve, a lower cover plate, a base, a limit spring and a bearing;

[0014] Further, the base is a circular groove structure;

[0015] Further, the center of the base is vertically equipped with a shaft through a bushing and a limit spring;

[0016] Furthermore, a protective sleeve is mounted on the upper portion of the circumferential platform of the base;

[0017] Further, a set of stators is assembled at the bottom of the sheath and encapsulated by a lower cover plate and bolts;

[0018] Further, a set of stators is assembled on the top of the sheath and encapsulated by an upper cover plate and bolts;

[0019] Further, the stator is electrically connected to the detection circuit;

[0020] Furthermore, a rotor to be tested is mounted on the shaft; the rotor to be tested needs to rotate at a constant speed in a test stator during the test project, and the aluminum bars of the rotor cut the magnetic lines of force generated by the excitation magnetic field to generate an induced electromotive force in the stator.

[0021] Furthermore, the coaxiality of the two sets of stators is ensured by the sheath.

[0022] Further, the stator includes: a stator core, a voltage detection coil and an excitation coil;

[0023] Further, the voltage detection coil and the excitation coil are relatively mounted on the stator core;

[0024] Furthermore, the voltage detection coil and the excitation coil mounted on the stators above and below the sheath are arranged opposite to each other.

[0025] Furthermore, the voltage detection coil and the excitation coil are wound by enameled copper wire, and the number of turns of the enameled copper wire is 30±5 turns;

[0026] Furthermore, the thickness of the stator core is 15±1 mm;

[0027] Furthermore, it is ensured that when the excitation coil is energized, a sufficiently large reverse excitation magnetic field can be generated in the stator core, and at the same time, the voltage detection coil can accurately detect the voltage and power.

[0028] Furthermore, the rotor under test rotates uniformly in the stator under test at a speed of 100-200 rpm.

[0029] Further, the detection circuit includes: a power supply, a power supply voltage meter and a power meter;

[0030] Further, the power supply and the power supply voltmeter are connected to the two excitation coils through wires, power is supplied to the excitation coils, and an excitation magnetic field is generated in the stator core;

[0031] Furthermore, the power meter is connected to two poles of the two voltage detection coils through a wire.

[0032] Furthermore, the voltage of the power supply is 5±0.1V.

[0033] Furthermore, during the test, the rotor under test needs to rotate at a constant speed in the test stator at a speed of 100-200 rpm. The rotor aluminum bar cuts the magnetic lines of force generated by the excitation magnetic field to generate current. Because the excitation coils of the two stators are installed in opposite directions, after the rotor rotates, the induced currents generated in the upper and lower parts of the aluminum bar are equal in magnitude and opposite in direction. The current flows in the following directions: Figure 4 As shown in the figure, if the punching sheet is completely insulated from the core, the two opposite currents generated in the aluminum bar cancel each other out, no back electromotive force is detected in the voltage detection coil of the stator, and no power is measured by the power meter; when the stray loss of the rotor is large, Figure 4 The current flows through cast aluminum conductor bar - iron core - cast aluminum conductor bar - aluminum end ring - cast aluminum conductor bar, and the back electromotive force is detected in the voltage detection coil of the test stator.

[0034] Furthermore, after the induced electromotive force is generated in the voltage detection coil, the induced power is measured by a power meter.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1. The motor rotor loss detection device provided by the present invention has an excitation coil and a voltage detection coil installed in a stator respectively, and detects the rotor loss by a reverse excitation method. The structure is simple and practical, and can detect and determine the rotor stray loss efficiently and quickly.

[0037] 2. The motor rotor loss detection device provided by the present invention can generate a stable induced current in the rotor aluminum bar and then generate a stable power value in the power meter as long as the tested rotor rotates stably and at a constant speed. The test data is stable with small fluctuations, and data recording is convenient and fast.

[0038] In summary, the application of the technical solution of the present invention solves the problem of detecting large stray losses of the rotor caused by poor cast aluminum, with high test accuracy, and can effectively detect and identify rotors with large stray losses, thereby improving detection efficiency. In theory, after the rotor rotates, the induced current generated in the upper and lower parts of the aluminum bar is equal in magnitude and opposite in direction. If the punching sheet is completely insulated from the core, there will be no current flow, and there will be no back electromotive force detection in the voltage detection coil of the test stator, and no power will be measured by the power meter; only when the stray loss of the rotor is large can the power value be detected, but in the actual test process, all rotors can test the corresponding values, and multiple sets of data need to be tested to determine the limit value of defective products with large stray losses based on the actual test results. At the same time, for defective products such as broken rotor bars, since there is no induced current generated in their rotors, the device cannot be used for detection, and other detection devices need to be used for auxiliary detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0040] Figure 1 It is the assembly diagram of the mechanical part of the present invention;

[0041] Figure 2 A top view of the stator structure of the present invention;

[0042] Figure 3 This is a schematic diagram of the stator structure of the present invention;

[0043] Figure 4 It is the electrical wiring schematic diagram of the present invention;

[0044] Figure 5 Schematic diagram of rotor current flow in the present invention.

[0045] In the figure: 1, stator core 2, voltage detection coil 3, excitation coil 4, measured rotor 5, shaft 6, upper cover 7, bolt 8, sheath 9, lower cover 10, base 11, limit spring 12, bearing 13, power supply 14, power supply voltmeter 15, power meter. DETAILED DESCRIPTION

[0046] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0047] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0049] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0050] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0051] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0052] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0053] like Figure 2-3 As shown, the present invention provides a motor rotor loss detection device, and the stator tested in the detection device includes: a stator core 1, a voltage detection coil 2, and an excitation coil 3; a set of voltage detection coil 2 and excitation coil 3 are installed on each stator.

[0054] like Figure 1As shown, the present invention provides a motor rotor loss detection device including: a stator core 1, a voltage detection coil 2, an excitation coil 3, a rotor to be measured 4, a shaft 5, an upper cover plate 6, a bolt 7, a sheath 8, a lower cover plate 9, a base 10, a limit spring 11, a bearing 12, a power supply 13, a power supply voltage meter 14, and a power meter 15. The voltage detection coils 2 and the excitation coils 3 of the two stators are placed in opposite directions, the stator is installed in the sheath 8, and is fixed on the base 10 through the upper cover plate 6, the bolt 7, and the lower cover plate 9, the rotor to be measured 4 is installed on the shaft 5 for rotation operation, the shaft 5 is supported by the bearing 12, and the bearing 12 is installed on the base 10 through the limit spring 11.

[0055] Figure 4 This is the electrical wiring diagram of the detection device. The stator excitation coils 3-(1) and 3-(2) are installed and wired in opposite directions and symmetrically. They are powered by a power supply 13, generating reverse excitation magnetic fields in the upper stator core 1-(1) and the lower stator core 1-(2), respectively, so that the rotor 4 generates currents in opposite directions when it rotates. After the induced electromotive force is generated in the voltage detection coil 2, the induced power is measured by a power meter 15.

[0056] Figure 5 This is a schematic diagram of the current flow in the rotor aluminum bars. The rotor aluminum bars cut the magnetic lines of force generated by the excitation magnetic field to generate current. Because the excitation coils of the two stators are installed in opposite directions, the induced currents generated in the upper and lower parts of the aluminum bars are equal in magnitude and opposite in direction. If the punching sheets and the iron core are completely insulated, the two opposite currents generated in the aluminum bars will cancel each other out. When the stray losses of the rotor are large, the current flow of cast aluminum bars - iron core - cast aluminum bars - aluminum end rings - cast aluminum bars will be generated in the rotor.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A motor rotor loss detection device, characterized in that: The motor rotor loss detection device adopts two stators to be excited in opposite directions respectively, and detects and determines the rotor stray loss by detecting the power value detected by the detection coil; The motor rotor loss detection device comprises: a rotor to be tested (4), a shaft (5), an upper cover plate (6), bolts (7), a sleeve (8), a lower cover plate (9), a base (10), a limit spring (11) and a bearing (12); The base (10) is a circular groove structure; The center of the base (10) is vertically equipped with a shaft (5) through a bearing (12) and a limit spring (11); The upper part of the circumferential platform of the base (10) is equipped with a protective sleeve (8); A set of stators is assembled at the bottom of the sheath (8) and is encapsulated by a lower cover plate (9) and bolts (7); A set of stators is installed on the top of the sheath (8) and is encapsulated by an upper cover plate (6) and bolts (7); The stator is electrically connected to the detection circuit; The shaft (5) is mounted with a rotor (4) to be measured; The rotor (4) to be tested needs to rotate at a constant speed in the test stator during the test process, and the aluminum bars of the rotor cut the magnetic lines of force generated by the excitation magnetic field, thereby generating an induced electromotive force in the stator.

2. The motor rotor loss detection device according to claim 1, characterized in that: The coaxiality of the two sets of stators is ensured by the sheath (8).

3. The motor rotor loss detection device according to claim 1, characterized in that: The stator comprises: a stator core (1), a voltage detection coil (2) and an excitation coil (3); The voltage detection coil (2) and the excitation coil (3) are relatively mounted on the stator core (1); The voltage detection coil (2) and the excitation coil (3) mounted on the stators above and below the sheath (8) are arranged opposite to each other.

4. The motor rotor loss detection device according to claim 3 is characterized in that: The voltage detection coil (2) and the excitation coil (3) are wound by enameled copper wire, and the number of turns of the enameled copper wire is 30±5 turns; The thickness of the stator core (1) is 15±1 mm; It is ensured that when the excitation coil (3) is energized, a sufficiently large reverse excitation magnetic field can be generated in the stator core (1), and at the same time, the voltage detection coil (2) can accurately detect the voltage and power.

5. The motor rotor loss detection device according to claim 1, characterized in that: The rotor (4) under test rotates at a constant speed in the stator under test, with the rotation speed being 100-200 revolutions per minute.

6. The motor rotor loss detection device according to claim 1, characterized in that: The detection circuit comprises: a power supply (13), a power supply voltage meter (14) and a power meter (15); The power supply (13) and the power supply voltmeter (14) are connected to the two excitation coils via wires to supply power to the excitation coils (3) and generate an excitation magnetic field in the stator core (1); The power meter (15) is connected to the two poles of the two voltage detection coils (2) via a wire.

7. The motor rotor loss detection device according to claim 6, characterized in that: The voltage of the power supply (13) is 5±0.1V.

8. The motor rotor loss detection device according to claim 3, characterized in that: After the induced electromotive force is generated in the voltage detection coil (2), the induced power is measured by a power meter (15).

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