Motor shaft current measuring device

Abstract

The invention provides a motor shaft current measuring device, which comprises a switching disc, and is characterized in that the switching disc is provided with a first carbon brush ring, a second carbon brush ring and an insulation part, and the insulation part is used for being fixedly connected with a rotor; the testing carbon brush is arranged in the first carbon brush ring in a sliding mode, the testing carbon brush is electrically connected with the switching disc through the first carbon brush ring, and one end, far away from the switching disc, of the testing carbon brush is connected with a current display; and the grounding carbon brush is used in cooperation with the second carbon brush ring, and the grounding carbon brush is configured in the mode that when the switching disc rotates along with the rotor, the grounding carbon brush and the switching disc are alternately and electrically connected through the second carbon brush ring. Compared with the prior art, the motor shaft current measuring device provided by the invention can detect the numerical value of the motor shaft current in real time, and provides technical support for the suppression design of the motor shaft current.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a motor shaft current measuring device. Background Technology

[0002] Shaft electro-erosion (also known as bearing galvanic corrosion) is a common failure mode in wind power generation systems, primarily caused by shaft voltage and shaft current. When the shaft voltage accumulates to a certain value (usually exceeding the insulation withstand capability of the lubricating oil film, approximately 0.5V or higher), it breaks down the bearing oil film, forming a shaft current. This current generates an electric arc discharge when passing through the bearing raceway and rolling elements, resulting in tiny electro-erosion pits (approximately 5-8 μm in diameter) on the contact surface, which gradually expand into typical "washboard" textured patterns. Electro-erosion further induces grease carbonization and additive failure, accelerating bearing wear and degradation, ultimately leading to abnormal bearing noise, increased vibration, and even failure. Shaft current is the most direct cause of shaft electro-erosion, but it is difficult to detect the magnitude of the shaft current in real time using current technology.

[0003] Therefore, there is an urgent need for a motor shaft current measuring device that can detect the value of motor shaft current in real time, providing technical support for motor shaft current suppression design. Summary of the Invention

[0004] To address the technical problem of difficulty in real-time detection of shaft current in existing technologies, this invention provides a motor shaft current measuring device capable of real-time detection of motor shaft current values, providing technical support for motor shaft current suppression design.

[0005] A motor shaft current measuring device, comprising: The adapter plate is provided with a first carbon brush ring, a second carbon brush ring and an insulating part, the insulating part being used for fixed connection with the rotor; The test carbon brush is slidably disposed within the first carbon brush ring, and the test carbon brush is electrically connected to the adapter plate through the first carbon brush ring. The end of the test carbon brush away from the adapter plate is connected to the current display. A grounding carbon brush, used in conjunction with the second carbon brush ring, is configured such that when the transfer plate rotates with the rotor, the grounding carbon brush and the transfer plate are alternately electrically connected through the second carbon brush ring.

[0006] Preferably, the second carbon brush ring is a ring structure, at least two second carbon brush rings are provided, the second carbon brush rings are concentrically arranged, and the second carbon brush rings are spaced apart around the axis of the adapter plate.

[0007] Preferably, the first carbon brush ring is a solid ring structure.

[0008] Preferably, the first carbon brush ring is disposed outside the second carbon brush ring; or, The second carbon brush ring is disposed outside the first carbon brush ring.

[0009] Preferably, the adapter plate is made of metal material, and an insulating layer is provided at the connection between the adapter plate and the rotor, with the insulating layer covering the position to form an insulating part.

[0010] Preferably, a mounting hole is provided on the insulating part for fixing the rotor with bolts.

[0011] Preferably, both the current display and the grounding carbon brush are grounded.

[0012] Preferably, it further includes: A bracket is fixedly connected to the gearbox end cover or the test end cover, and the test carbon brush and the grounding carbon brush are disposed on the bracket.

[0013] Compared with the prior art, the motor shaft current measuring device provided by the present invention includes a transfer plate, a test carbon brush, and a grounding carbon brush. The transfer plate is provided with a first carbon brush ring, a second carbon brush ring, and an insulating part. The test carbon brush is slidably connected to the first carbon brush ring and electrically connected to the transfer plate through the first carbon brush ring. The side of the test carbon brush away from the transfer plate is connected to a current display. The grounding carbon brush works in conjunction with the second carbon brush ring. The grounding carbon brush is configured such that when the transfer plate rotates with the rotor, the grounding carbon brush and the transfer plate are alternately electrically connected through the second carbon brush ring. When the grounding carbon brush is electrically connected to the second carbon brush, the adapter plate is grounded through the grounding carbon brush. The current display shows the shaft current when the adapter plate is grounded. If the shaft current when the adapter plate is grounded is too large, additional measures can be considered to eliminate the shaft current. When the grounding carbon brush is separated from the adapter plate, the current display shows the shaft current when the adapter plate is not grounded. By comparing the shaft current when the adapter plate is grounded and when it is not grounded, the effect of the adapter plate on the suppression of shaft current after grounding through the grounding carbon brush is reflected, thus providing technical support for the design of motor shaft current suppression.

[0014] Therefore, compared with the prior art, the motor shaft current measuring device provided by the present invention can detect the value of the shaft current in real time when the adapter plate is grounded and not grounded, providing technical support for the design of motor shaft current suppression. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic diagram of a motor shaft current measuring device provided in an embodiment of the present invention; Figure 2 A front view of a motor shaft current measuring device provided in an embodiment of the present invention; Figure 3 for Figure 2 A sectional view; Figure 4 This is a schematic diagram of a converter plate provided in an embodiment of the present invention; Figure 5 This is a partial schematic diagram of a motor shaft current measuring device provided in an embodiment of the present invention.

[0017] Reference numerals in the attached diagram: 1. Adapter plate; 21. Rotor; 22. Stator; 3. First carbon brush ring; 4. Second carbon brush ring; 5. Test carbon brush; 6. Current indicator; 7. Grounding carbon brush; 8. Mounting hole; 9. Bracket. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0020] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0021] like Figures 1 to 5 As shown, the present invention provides a motor shaft current measuring device, comprising: a transfer plate 1, wherein a first carbon brush ring 3, a second carbon brush ring 4 and an insulating part are disposed on the transfer plate 1, the insulating part of the transfer plate being used for fixed connection with the rotor; a test carbon brush 5, which is slidably disposed within the first carbon brush ring 3, and the test carbon brush 5 is electrically connected to the transfer plate 1 through the first carbon brush ring 3, and the end of the test carbon brush 5 away from the transfer plate 1 is connected to a current display 6; and a grounding carbon brush 7, which is used in conjunction with the second carbon brush ring 4, and the grounding carbon brush 7 is configured such that when the transfer plate 1 rotates with the rotor 21, the grounding carbon brush 7 and the transfer plate 1 are alternately electrically connected through the second carbon brush ring 4.

[0022] Generator shaft erosion (also known as bearing electro-corrosion) is a common failure mode in wind power generation systems, mainly caused by shaft voltage and shaft current. Its mechanism lies in the fact that factors such as magnetic circuit imbalance, leakage flux, or common-mode voltage of the frequency converter during generator operation induce shaft voltage in the rotating system. When the shaft voltage accumulates to a certain value (usually exceeding the insulation withstand capability of the lubricating oil film, approximately 0.5V or higher), it breaks down the bearing oil film, forming a shaft current. This current generates an arc discharge when passing through the bearing raceway and rolling elements, resulting in tiny electro-erosion pits (approximately 5-8 μm in diameter) on the contact surface, which gradually expand into typical "washboard" textured patterns. Electro-erosion further leads to grease carbonization, additive failure, accelerated bearing wear and degradation, ultimately causing abnormal bearing noise, increased vibration, and even failure. Statistics show that approximately 30% of generator damage is related to shaft current, especially in doubly-fed asynchronous wind turbines using frequency converters.

[0023] Regarding the problem of shaft erosion, although current generators use an insulated flange structure, factors such as magnetic circuit asymmetry, uneven air gap between stator 22 and rotor 21, and high-frequency harmonic interference can still generate shaft voltage at both ends of the shaft, which in turn forms shaft current. This current forms a closed loop through the gearbox bearings, leading to erosion on the bearing surface and significantly shortening the bearing life.

[0024] Currently, shaft current is the most direct cause of shaft erosion, but existing technologies make it difficult to detect the magnitude of shaft current in real time, thus failing to provide technical support for the design of motor shaft current suppression.

[0025] Compared with the prior art, the motor shaft current measuring device provided by the present invention includes a transfer plate 1, a test carbon brush 5, and a grounding carbon brush 7. The transfer plate 1 is provided with a first carbon brush ring 3, a second carbon brush ring 4, and an insulating part. The insulating part of the transfer plate 1 is used for fixed connection with the rotor 21. The test carbon brush 5 is slidably disposed within the first carbon brush ring 3, and the test carbon brush 5 is electrically connected to the transfer plate 1 through the first carbon brush ring 3. The side of the test carbon brush 5 away from the transfer plate 1 is connected to a current display 6. The grounding carbon brush 7 works in conjunction with the second carbon brush ring 4. The grounding carbon brush 7 is configured such that when the transfer plate 1 rotates with the rotor 21, the grounding carbon brush 7 and the transfer plate 1... The two are alternately electrically connected via the second carbon brush ring 4. When the grounding carbon brush 7 is electrically connected to the second carbon brush ring 4, the adapter plate 1 is grounded through the grounding carbon brush 7. The current display 6 shows the shaft current when the adapter plate 1 is grounded. If the shaft current when the adapter plate 1 is grounded is too large, additional measures can be considered to eliminate the shaft current. When the grounding carbon brush 7 is separated from the adapter plate 1, the current display 6 shows the shaft current when the adapter plate 1 is not grounded. By comparing the shaft current when the adapter plate 1 is grounded and when it is not grounded, the effect of the adapter plate 1 on the suppression of shaft current after being grounded by the grounding carbon brush 7 is fed back, thus providing technical support for the design of motor shaft current suppression.

[0026] Without adapter plate 1, the shaft current is grounded through the gearbox bearing. However, by setting adapter plate 1, the shaft is isolated from the gearbox bearing and directly grounded. By measuring the shaft current grounded through adapter plate 1, the shaft current on the bearing when the motor is grounded through the bearing during use can be simulated, thus providing technical support for the design and use of the motor.

[0027] Therefore, compared with the prior art, the motor shaft current measuring device provided by the present invention can detect the value of the shaft current in real time when the adapter plate 1 is grounded and not grounded, providing technical support for the design of motor shaft current suppression.

[0028] In the above structure, the current display 6 in the embodiment of the present invention is specifically an oscilloscope.

[0029] In the above structure, as one embodiment, the adapter plate 1 in the motor shaft current measuring device of the present invention rotates so that the grounding carbon brush 7 has a first state of being electrically connected to the second carbon brush ring and a second state of being separated from the second carbon brush ring. When the grounding carbon brush 7 is in the first state, the grounding carbon brush 7 is electrically connected to the second carbon brush ring 4, and a circuit is formed between the grounding carbon brush 7, the adapter plate 1, the test carbon brush 5 and the current display 6. The current display 6 displays the current when the adapter plate 1 is grounded. When the grounding carbon brush 7 is in the second state, the grounding carbon brush 7 is separated from the second carbon brush ring 4.

[0030] More specifically, as one embodiment, the second carbon brush ring 4 in this invention is specifically a ring structure. At least two second carbon brush rings 4 are provided, concentrically arranged and spaced apart around the axis of the adapter plate 1. Thus, when the motor is running, the adapter plate 1 rotates with the rotor 21, and the grounding carbon brush 7 is periodically grounded through the second carbon brush ring 4. When the grounding carbon brush 7 is electrically connected to the second carbon brush ring 4, the current display 6 measures the shaft current signal when the adapter plate 1 is grounded. As the adapter plate 1 rotates, the grounding carbon brush 7 separates from the second carbon brush ring 4. At this time, the current display 6 measures the shaft current signal when the adapter plate 1 is not grounded.

[0031] In the above structure, as one embodiment, at least two second carbon brush rings 4 are provided in the present invention embodiment. The second carbon brush rings 4 are arranged concentrically and are spaced apart around the axis of the adapter plate 1.

[0032] Furthermore, the second carbon brush ring 4 is preferably configured as any one of 2, 3 or 4.

[0033] Furthermore, as one specific implementation, the first carbon brush ring 3 in this embodiment of the invention is specifically a complete ring structure, and the test carbon brush 5 and the adapter plate 1 are always electrically connected through the first carbon brush ring 3.

[0034] Furthermore, as one specific implementation, in this practical embodiment, the first carbon brush ring 3 is disposed outside the second carbon brush ring 4, or the second carbon brush ring 4 is disposed outside the first carbon brush ring 3.

[0035] Furthermore, the adapter plate 1 is specifically made of metal material, and an insulating layer is provided on the outer surface of the part of the adapter plate 1 that is connected to the rotor, and the area covered by the insulating layer forms the insulating part of the adapter plate 1.

[0036] Furthermore, to facilitate the installation of the adapter plate 1, as one specific embodiment of the invention, the motor shaft current measuring device further includes mounting holes 8. The mounting holes 8 are disposed on the insulating portion of the adapter plate 1 and are used for fixed connection with the rotor 21 via bolts. Multiple mounting holes 8 are provided, and these holes are evenly spaced around the axial direction of the adapter plate 1.

[0037] Furthermore, both the current display 6 and the grounding carbon brush 7 are grounded; specifically, both the current display 6 and the grounding carbon brush 7 are grounded via wires.

[0038] Furthermore, as one implementation method, such as Figure 5As shown, the motor shaft current measuring device in this embodiment of the invention also includes a bracket 9, which is fixedly connected to the gearbox end cover or the test end cover. The test carbon brush 5 and the grounding carbon brush 7 are both mounted on the bracket 9.

[0039] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of the present invention, but these improvements all fall within the protection scope of the present invention.

Claims

1. An electrical machine shaft current measuring device, characterized in that, The utility model relates to a kind of motor shaft current measurement devices, including: Adapter disc (1), first carbon brush ring (3), second carbon brush ring (4) and insulating part are provided on the adapter disc (1), and the insulating part is used to be fixedly connected with rotor; Test carbon brush (5) is slidably arranged in the first carbon brush ring (3), and the test carbon brush is electrically connected between the test carbon brush and the adapter disc by the first carbon brush ring (3), and one end of the test carbon brush (5) away from the adapter disc (1) is connected with current display (6); Ground carbon brush (7) is used in cooperation with the second carbon brush ring (4), and the ground carbon brush (7) is configured to be alternately electrically connected between the ground carbon brush (7) and the adapter disc by the second carbon brush ring (4) when the adapter disc (1) rotates with rotor (21).

2. The motor shaft current measurement device of claim 1, wherein: The second carbon brush ring (4) is specifically annular structure, the second carbon brush ring (4) is provided with at least two, and the second carbon brush ring (4) is concentrically arranged, and the second carbon brush ring (4) is arranged at intervals around the axis direction of the adapter disc (1).

3. The motor shaft current measurement device of claim 2, wherein: The first carbon brush ring (3) is specifically whole ring structure.

4. The motor shaft current measurement device of claim 3, wherein: The first carbon brush ring (3) is arranged outside the second carbon brush ring (4);Or, The second carbon brush ring (4) is arranged outside the first carbon brush ring (3).

5. The motor shaft current measurement device of any one of claims 1 to 4, wherein: The adapter disc (1) is made of metal material, and an insulating layer is arranged at the connecting part of the adapter disc (1) and the rotor, and the position covered by the insulating layer forms an insulating part.

6. The motor shaft current measurement device of any one of claims 1 to 4, further comprising: Mounting hole (8) arranged on the insulating part, the mounting hole (8) is used to be fixedly connected between the rotor (21) by bolt.

7. The motor shaft current measurement device of any one of claims 1 to 4, wherein: The current display (6) and the ground carbon brush (7) are both grounded.

8. The motor shaft current measurement device of any one of claims 1 to 4, further comprising: Support (9), the support (9) is fixedly connected with gear box end cover or test end cover, and the test carbon brush (5) and the ground carbon brush (7) are arranged on the support (9). ​ ​

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