Generator convenient for measuring shaft current and shaft current testing method thereof

Abstract

The invention relates to a generator facilitating shaft current measurement and a shaft current testing method thereof.The generator comprises a rotating shaft, the output end of the rotating shaft is sleeved with a bearing, the end face of the output end of the rotating shaft is connected with a rotor through a flange plate, and the side, opposite to the rotating shaft, of the flange plate is connected with a special-shaped grounding ring; the stator is sleeved with a machine base, a stator coil is further arranged between the rotor and the stator, a front end cover is assembled at the front end of the machine base, a rear end cover is assembled at the rear end of the machine base, the rear end cover is connected with the grounding end of a grounding carbon brush, one end of a brush body of the grounding carbon brush is connected with a special-shaped grounding ring, and a first insulator is clamped at the connecting position of the flange plate and the rotating shaft. The two sides of the first insulator are respectively provided with a first grounding block and a second grounding block, and the rotating shaft is sleeved with an AC flexible current probe. The generator is convenient for accurately measuring the shaft current passing through the bearing, improves the accuracy of the measurement result, and is beneficial to avoiding the problem of electrocorrosion.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a generator which is convenient for measuring shaft current and a method for testing the shaft current thereof. Background Art

[0002] Semi-direct-drive permanent magnet synchronous generators have become one of the widely used forms in wind power generation systems due to their high reliability and relatively low cost per kilowatt-hour. However, semi-direct-drive generators are prone to bearing electrical corrosion during operation, which causes huge economic losses, especially for offshore units, which usually result in economic losses of millions of RMB. Therefore, the problem of bearing electrical corrosion has become one of the bottlenecks in industrial development and is an urgent issue in the industry and needs to be solved urgently. Since shaft current is the most direct cause of bearing electrical corrosion, accurate measurement of shaft current is the key to improving the problem of motor electrical corrosion. During the test, due to the difficulty in testing shaft current, the shaft current usually measured is actually the current passing through the grounding brush braid. The current passing through the grounding brush braid is not the shaft current passing through the bearing, but a sub-current of the shaft current. Such test results can easily lead to misjudgment by staff, resulting in greater economic losses. Summary of the invention

[0003] In view of the problems existing in the prior art, the purpose of the present invention is to provide a generator that is convenient for measuring shaft current and a testing method for shaft current. The generator is convenient for accurately measuring the shaft current passing through the bearing, improving the accuracy of the measurement results, and has a small capacitance, which is conducive to reducing electrical corrosion.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention proposes a generator that is convenient for measuring shaft current, comprising a rotating shaft, wherein the output end of the rotating shaft is sleeved with a bearing, the end face of the output end of the rotating shaft is connected to the rotor through a flange, the flange is connected to a special-shaped grounding ring on the side facing away from the rotating shaft, a stator is sleeved on the rotor, a machine base is sleeved on the outer periphery of the stator, a stator coil is also arranged between the rotor and the stator, a front end cover is equipped at the front end of the machine base, a rear end cover is equipped at the rear end, the rear end cover is connected to the grounding end of a grounding carbon brush, one end of the brush body of the grounding carbon brush is connected to the special-shaped grounding ring, a first insulator is clamped at the connection between the flange and the rotating shaft, a first grounding block and a second grounding block are respectively arranged on both sides of the first insulator, and an AC flexible current probe is sleeved on the rotating shaft.

[0006] Furthermore, the AC flexible current probe is located between the first insulator and the bearing and has a gap with the periphery of the rotating shaft, and the circumference of the AC flexible current probe is fixedly connected to the fixed axis of the outer ring of the bearing.

[0007] Furthermore, a second insulator is sandwiched between the flange and the rotor.

[0008] Furthermore, a third insulator and a fourth insulator are spaced apart on the base near one end of the front end cover, the third insulator and the fourth insulator are located between the stator and the front end cover, a third grounding block is provided on the side of the third insulator away from the fourth insulator, a fourth grounding block is provided on the side of the fourth insulator away from the third insulator, and a fifth grounding block is provided between the third insulator and the fourth insulator.

[0009] A shaft current testing method based on the generator described above connects an AC flexible current probe to an oscilloscope via an integrator to test the shaft current.

[0010] A shaft current testing method based on the above generator is characterized in that any two of the third grounding block, the fourth grounding block and the fifth grounding block are short-circuited by a short-circuit wire, and then the current on the short-circuit wire is tested.

[0011] Furthermore, the current on the short-circuit wire is tested by using an AC flexible current probe.

[0012] Furthermore, the current on the short-circuit wire is tested by an ammeter.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) The generator shaft of the present invention is pre-mounted with an AC flexible current probe, which is convenient for directly and accurately measuring the shaft current. When measuring the shaft current, it is only necessary to connect the AC flexible current probe to an oscilloscope through an integrator, which is simple and reliable.

[0015] (2) The generator flange of the present invention is provided with double insulation, and the base is also provided with double insulation at one end close to the front end cover. This double insulation setting can reduce capacitance, is beneficial to suppress shaft current, and alleviates the problem of electrical corrosion of the generator.

[0016] (3) The present invention proposes to first connect a short-circuit wire in parallel to the insulator on the machine base near one end of the front cover, and then test the current on the short-circuit wire. The current on the short-circuit wire is the shaft current to be measured. This indirect method of testing the shaft current is also simple and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the generator of the present invention;

[0018] Figure 2 The equivalent circuit diagram formed by the generator shaft current;

[0019] Reference numerals:

[0020] 1. Rotating shaft, 2. Bearing, 3. Flange, 4. Rotor, 5. Stator coil, 6. Stator, 7. Machine base, 8. Front cover, 9. Rear cover, 10. Grounding carbon brush, 11. Special-shaped grounding ring, 12. First insulator, 13. AC flexible current probe, 14. Second insulator, 15. Third insulator, 16. Fourth insulator, 17. Short-circuit wire, 18. Converter. DETAILED DESCRIPTION

[0021] The embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0023] In the following description, specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0024] Example 1

[0025] refer to Figure 1 The present embodiment provides a generator for measuring shaft current, including a rotating shaft 1, wherein the output end of the rotating shaft 1 is sleeved with a bearing 2, the end face of the output end of the rotating shaft 1 is connected to the rotor 4 through a flange 3, the flange 3 is connected to a special-shaped grounding ring 11 on the side facing away from the rotating shaft 1, the rotor 4 is sleeved with a stator 6, the outer periphery of the stator 6 is sleeved with a base 7, a stator coil 5 is further arranged between the rotor 4 and the stator 6, the stator coil 5 is electrically connected to a converter 18 outside the generator, the front end of the base 7 is equipped with a front cover 8, the rear end is equipped with a rear cover 9, the rear end of the base 7 is connected to the grounding carbon brush 10 The grounding end is connected, one end of the brush body of the grounding carbon brush 10 is connected to the special-shaped grounding ring 11, a first insulator 12 is clamped at the connection between the flange 3 and the rotating shaft 1, and a second insulator 14 is clamped at the connection between the flange 3 and the rotor 4. The first insulator 12 is respectively provided with a first grounding block and a second grounding block on both sides, and an AC flexible current probe 13 is sleeved on the rotating shaft 1. The AC flexible current probe 13 is preferably located between the first insulator 12 and the bearing 1 and has a gap with the outer periphery of the rotating shaft 1. The circumference of the AC flexible current probe 13 is fixedly connected to the fixed axis of the outer ring of the bearing 2.

[0026] Furthermore, a third insulator 15 and a fourth insulator 16 are spaced apart on the base 7 near one end of the front end cover, the third insulator 15 and the fourth insulator 16 are located between the stator and the front end cover 8, a third grounding block is provided on the side of the third insulator 15 away from the fourth insulator 16, a fourth grounding block is provided on the side of the fourth insulator 16 away from the third insulator 15, and a fifth grounding block is provided between the third insulator 15 and the fourth insulator 16.

[0027] The equivalent circuit diagram of the shaft current formed in this embodiment is shown in FIG. Figure 2 , C in the figure wf Represents the stator winding and stator coupling capacitance; C wr Represents the coupling capacitance between stator winding and rotor; C rf Represents the coupling capacitance between the rotor and the stator; bearing capacitance C b =C b1 +C b2 ; R represents a grounding carbon brush, C4 represents a first insulator 13, C3 represents a second insulator 14, C1 and C2 represent a third insulator 15 and a fourth insulator 16 respectively. In this embodiment, an AC flexible current probe 13 is sleeved on the internal shaft 1 of the motor. When measuring the shaft current, it is only necessary to connect the AC flexible current probe 13 to the oscilloscope through an integrator. It is simple and reliable. There is a gap between the AC flexible current probe 13 and the periphery of the shaft 1, and the circumference is fixedly connected to the fixed axis of the outer ring of the bearing 2. During the rotation of the shaft 1, the AC flexible current probe 13 and the shaft 1 do not interfere with each other.

[0028] Example 2

[0029] refer to Figure 1 This embodiment proposes a method for testing the shaft current of a generator, which can indirectly measure the shaft current. The method is to connect a short-circuit wire in parallel to the insulator on the main line of the shaft current loop. Since the short-circuit wire short-circuits the insulator, and since there are other insulators (first insulators) on the main line of the shaft current loop, the short-circuit wire will hardly affect the actual shaft current. At the same time, the current on the short-circuit wire is the shaft current. It is simple and fast, and the result is reliable. When testing the shaft current through the short-circuit wire, first short-circuit any two of the third grounding block, the fourth grounding block and the fifth grounding block through the short-circuit wire 17, and then test the current on the short-circuit wire 17, that is, connect the short-circuit wire 17 in parallel with the third insulator 15 or the fourth insulator 16, or treat the third insulator 15 and the fourth insulator 16 as a whole, and connect the short-circuit wire 17 to the whole. The current on the short-circuit wire can be measured with an ammeter, an AC flexible current probe or other current measuring equipment.

[0030] Although the present invention has been described in detail in this specification by means of general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto on the basis of the present invention. Therefore, these modifications or improvements made without departing from the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A generator for measuring shaft current, characterized in that: The invention comprises a rotating shaft (1), wherein the output end of the rotating shaft (1) is sleeved with a bearing (2), the end surface of the output end of the rotating shaft (1) is connected to a rotor (4) via a flange (3), the flange (3) is connected to a special-shaped grounding ring (11) on the side facing away from the rotating shaft, a stator (6) is sleeved on the rotor (4), a base (7) is sleeved on the periphery of the stator (6), a stator coil (5) is also arranged between the rotor (4) and the stator (6), a front end cover (8) is arranged at the front end of the base (7), a rear end cover (9) is arranged at the rear end, the rear end cover (9) is connected to the grounding end of a grounding carbon brush (10), one end of the brush body of the grounding carbon brush (10) is connected to the special-shaped grounding ring (11), a first insulator (12) is clamped at the connection between the flange (3) and the rotating shaft (1), a first grounding block and a second grounding block are arranged on both sides of the first insulator (12), and an AC flexible current probe (13) is sleeved on the rotating shaft (1).

2. According to a generator for measuring shaft current according to claim 1, the AC flexible current probe (13) is located between the first insulator (12) and the bearing (2) and has a gap with the periphery of the rotating shaft (1), and the circumference of the AC flexible current probe (13) is fixedly connected to the fixed axis of the outer ring of the bearing (2).

3. A generator for measuring shaft current according to claim 1, characterized in that: A second insulator (14) is clamped at the connection between the flange (3) and the rotor (4).

4. A generator for measuring shaft current according to claim 1, characterized in that: A third insulator (15) and a fourth insulator (16) are arranged at intervals on the base (7) near one end of the front end cover; the third insulator (15) and the fourth insulator (16) are located between the stator (6) and the front end cover (8); a third grounding block is arranged on a side of the third insulator (15) away from the fourth insulator (16); a fourth grounding block is arranged on a side of the fourth insulator (16) away from the third insulator (15); and a fifth grounding block is arranged between the third insulator (15) and the fourth insulator (16).

5. A method for testing the shaft current of a generator according to any one of claims 1 to 4, characterized in that: The AC flexible current probe (13) is connected to an oscilloscope via an integrator to test the shaft current.

6. A method for testing the shaft current of a generator according to claim 4, characterized in that: Any two of the third grounding block, the fourth grounding block and the fifth grounding block are short-circuited by a short-circuit wire (17), and then the current on the short-circuit wire (17) is tested.

7. A generator shaft current testing method according to claim 6, characterized in that: The current on the short-circuit wire (17) is tested using an AC flexible current probe.

8. A generator shaft current testing method according to claim 6, characterized in that: The current on the short-circuit wire (17) is tested by an ammeter.

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