Structure and method for preventing electro-corrosion of semi-direct-drive gearbox

Abstract

The invention discloses a structure and method for preventing electro-corrosion of a semi-direct-drive gearbox, and relates to the field of electro-corrosion prevention of the semi-direct-drive gearbox, the structure comprises a conductive part, a carbon brush and a plurality of grounding cables, the conductive part is provided with a plurality of cable connection points, and the conductive part is installed on a grounding point of a cabin; each cable connection point on the conductive part is connected with a stator base, a junction box and an end cover of the semi-direct-drive generator through at least one grounding cable. The carbon brush is installed on a hollow pipe of the semi-direct-drive gearbox and makes contact with the hollow pipe, and the carbon brush is connected with a grounding point on the engine room through a grounding cable. According to the invention, the influence of common-mode voltage on the gearbox is reduced by adding the generator grounding point and grounding the gearbox hollow tube.

Description

Technical Field

[0001] This invention relates to the field of preventing electro-corrosion in semi-direct drive gearboxes, and in particular to a structure and method for preventing electro-corrosion in semi-direct drive gearboxes. Background Technology

[0002] In wind turbines, compact semi-direct drive gearboxes are commonly used transmission chains, with their input end connected to the wind turbine shaft and their output end connected to the generator. Electro-corrosion within semi-direct drive gearboxes is a prevalent problem in the industry, generally attributed to shaft voltage during operation. While engineers have implemented various measures to address this issue, such as using filters, insulated bearings, or grounded carbon brushes, these methods can reduce or even eliminate electro-corrosion caused by shaft current. However, in practice, even with these methods, electro-corrosion is still observed in semi-direct drive gearboxes. Therefore, further research is needed to investigate the causes and solutions for electro-corrosion in semi-direct drive gearboxes. Summary of the Invention

[0003] The purpose of this invention is to provide a structure and method for preventing electro-corrosion in a semi-direct drive gearbox, addressing the aforementioned problems by increasing the grounding point of the generator and the grounding of the gearbox hollow tube, thereby reducing the impact of common-mode voltage on the gearbox.

[0004] The technical solution adopted in this invention is as follows: A structure for preventing electro-corrosion in a semi-direct drive gearbox, comprising conductive components, carbon brushes, and multiple grounding cables, wherein: The conductive component has multiple cable connection points and is installed on the grounding point of the engine compartment; each cable connection point on the conductive component is connected to the stator frame, junction box and end cover of the semi-direct drive generator respectively through at least one grounding cable. The carbon brush is mounted on and in contact with the hollow tube of the semi-direct drive gearbox, and the carbon brush is connected to the grounding point on the nacelle via a grounding cable.

[0005] Furthermore, among any two adjacent cable connection points on the conductive element, one connection point is closer to one side of the conductive element, and the other connection point is closer to the other side of the conductive element, and all cable connection points are staggered along the length of the conductive element.

[0006] Furthermore, the carbon brush is mounted on a bracket, which is mounted next to one end of the hollow tube, which is the end of the hollow tube closest to the stator frame.

[0007] Furthermore, cable connection points are provided on the stator frame, junction box, end cover, and carbon brushes, and the cable connection points on the stator frame, junction box, end cover, carbon brushes, and conductive components are all connection holes.

[0008] Furthermore, both ends of the grounding cable are connected to grounding plates, and the grounding plates are provided with connecting through holes. The screw in the bolt passes through the washer, the connecting through hole, the connecting hole, and the nut in sequence to connect the grounding cable to the cable connection point.

[0009] Furthermore, the cross-sectional area of ​​the copper core in the grounding cable is not less than 50 mm². 2 .

[0010] A method for preventing electro-corrosion in a semi-direct drive gearbox involves installing a conductive component with multiple cable connection points at the grounding point of the engine compartment. Each cable connection point on the conductive component is connected to the stator frame, junction box, and end cover of the semi-direct drive generator via at least one grounding cable. Install carbon brushes next to the hollow tube, make contact between the carbon brushes and the surface of the hollow tube, and connect the carbon brushes to the grounding point on the cabin via a grounding cable.

[0011] Furthermore, among any two adjacent cable connection points on the conductive component, one connection point is closer to one side of the conductive component, and the other connection point is closer to the other side of the conductive component.

[0012] Furthermore, the carbon brush is mounted on a bracket, which is mounted next to one end of the hollow tube, the end of the hollow tube being the end closest to the stator frame.

[0013] Furthermore, the cross-sectional area of ​​the copper core in the grounding cable shall not be less than 50 mm². 2 .

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: The key focus of this invention is to solve the technical problem of "severe electro-corrosion effect of common-mode voltage on semi-direct-drive gearboxes". By adding grounding cables to the stator frame, junction box, and end cover, as well as a grounding cable to the hollow tube, a low-impedance discharge path can be provided for the common-mode current. This allows the common-mode current to flow into the ground preferentially through the grounding wire, rather than forming a loop through the shaft and bearings. This effectively reduces shaft current, alleviates electro-corrosion of the gearbox bearings, improves the operational stability and reliability of the semi-direct-drive wind turbine, and extends the service life of the equipment. Attached Figure Description

[0015] The present invention will be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the assembly of the grounding cable and conductive components; The markings in the diagram are: 1-stator frame; 2-junction box; 3-end cover; 4-grounding cable; 5-conductive component; 51-cable connection point; 6-hollow tube; 7-carbon brush. Detailed Implementation

[0016] In the description of this specification, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," or "outer" appear to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, they are only for the convenience of describing this specification and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this specification.

[0017] Furthermore, the use of terms such as "horizontal" or "vertical" in this specification does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0018] In the description of this specification, it should also be noted that, unless otherwise expressly specified and limited, the terms “set up,” “install,” “connect,” and “link” should be interpreted broadly. For example, a link can be a fixed link, a detachable link, or an integral link; it can be a mechanical link or an electrical link; it can be a direct link or an indirect link through an intermediate medium; it can be a connection within two components.

[0019] Example 1 Research indicates that common-mode voltage is generated during the operation of semi-direct-drive wind turbine generators. This common-mode voltage is primarily caused by several factors. Firstly, the pulse-width modulation (PWM) technology used in the converter leads to rapid voltage switching and fluctuations during operation, resulting in a higher common-mode voltage within the generator. Secondly, the generator's structural characteristics, such as the distribution of the stator windings and parasitic capacitances between the windings and the rotor, also contribute to the generation of common-mode voltage. When the generator operates at high speed, these factors interact, causing the common-mode voltage to increase significantly.

[0020] Common-mode voltage generates shaft current on the gearbox shaft, which flows through the bearings or gear teeth. When this current "arc" breaks through the oil film, it instantly generates powerful energy, forming numerous molten pits on the bearing surface. Over time, the bearing raceways, balls, or gear teeth gradually wear and peel off, leading to increased gearbox vibration and noise. This severely affects the normal operation and service life of the gearbox, increasing maintenance costs and failure risks for the wind power generation system.

[0021] To effectively reduce the electro-corrosion of gearbox bearings caused by common-mode voltage, the following technical solution is proposed.

[0022] like Figures 1-2 As shown, a structure for preventing electro-corrosion in a semi-direct drive gearbox includes a conductive component 5, a carbon brush 7, and multiple grounding cables 4, wherein: The conductive element 5 has multiple cable connection points 51, and the conductive element 5 is installed on the grounding point of the engine compartment; each cable connection point 51 on the conductive element 5 is connected to the stator frame 1, junction box 2 and end cover 3 of the semi-direct drive generator through at least one grounding cable 4. The carbon brush 7 is mounted on and in contact with the hollow tube 6 of the semi-direct drive gearbox, and the carbon brush 7 is connected to the grounding point on the nacelle via the grounding cable 4.

[0023] In this embodiment, to address the technical problem of "severe electro-corrosion impact of common-mode voltage on the semi-direct-drive gearbox," a low-impedance discharge path for the common-mode current is provided by adding grounding cables 4 to the ground of the stator frame 1, junction box 2, and end cover 3, as well as the grounding cable 4 to the ground of the hollow tube 6. This allows the common-mode current to preferentially flow into the ground through the grounding wire, rather than forming a loop through the shaft and bearings. This effectively reduces shaft current, alleviates electro-corrosion of the gearbox bearings, improves the operational stability and reliability of the semi-direct-drive wind turbine, and extends the service life of the equipment.

[0024] In fact, although each grounding cable 4 has its own impedance, through the technical solution disclosed in this structure, each grounding cable 4 is actually connected in parallel with each other, and the circuits between the stator frame 1 of the semi-direct drive generator and the ground, between the junction box 2 and the ground, between the end cover 3 and the ground, and between the hollow tube 6 and the ground are also connected in parallel, thus forming a common mode current discharge path with lower impedance.

[0025] It should be noted that the conductive component 5 is designed to connect the grounding cable 4 to the grounding point of the engine room. Furthermore, the conductive component 5 can be made of conductive material into a sheet-like structure, such as copper busbar or aluminum busbar. Of course, the preferred material for the conductive component is copper busbar, which is made of copper busbar. The purpose is to better conduct common mode current without changing the structure of the engine room grounding point. The structure of the conductive component 5 can be designed according to the layout of the engine room grounding point, as long as the contact area between the conductive component 5 and the engine room grounding point meets the current density of common mode current discharge and can reliably connect the grounding cable 4.

[0026] Example 2 Based on Example 1, further feasible implementation methods are proposed.

[0027] One feasible implementation method is, for example Figure 2As shown, among any two adjacent cable connection points 51 on the conductive element 5, one connection point is closer to one side of the conductive element 5, and the other connection point is closer to the other side of the conductive element 5. All cable connection points 51 are staggered along the length of the conductive element 5. This distribution of cable connection points 51 not only makes it convenient to connect and install the grounding cable 4 to the conductive element 5 using bolts, but also maximizes the distance between any two adjacent cable connection points 51, thereby avoiding short circuits caused by air breakdown due to potential difference between adjacent cable connection points 51.

[0028] In one feasible implementation, the carbon brush 7 is mounted on a bracket, which is installed beside one end of the hollow tube 6, the end of the hollow tube 6 closest to the stator frame 1. The hollow tube 6 has its own impedance. Along the axial direction of the hollow tube 6, due to the impedance of the hollow tube 6, the potential on the hollow tube 6 gradually decreases from the end close to the stator frame 1 to the end far from the stator frame 1. That is, the end of the hollow tube 6 closest to the stator frame 1 has the maximum potential. Therefore, the carbon brush 7 is placed near this position, which can directly discharge the current formed by the maximum potential, thereby avoiding the formation of common-mode current on the hollow tube 6 and reducing the occurrence of electro-corrosion.

[0029] In one feasible implementation, cable connection points 51 are provided on the stator frame 1, junction box 2, end cover 3, and carbon brush 7. The cable connection points 51 on the stator frame 1, junction box 2, end cover 3, carbon brush 7, and conductive component 5 are all connection holes. Both ends of the grounding cable 4 are connected to grounding plates, and the grounding plates are provided with connection through holes. The bolts are passed through the washers, connection through holes, connection holes, and nuts in sequence to connect the grounding cable 4 to the cable connection points 51. This makes it convenient to install the grounding cable 4 and ensures stable installation.

[0030] Preferably, the connection holes on the stator frame 1, junction box 2, end cover 3 and carbon brush 7 that serve as cable connection points 51 can be the inherent threaded holes on the stator frame 1, junction box 2, end cover 3 and carbon brush 7, without the need for additional machining of cable connection points 51 or changes to the structure.

[0031] Preferably, the cable connection points 51 on the stator frame 1, junction box 2, and end cover 3 can be selected by arranging three points evenly on each side of the stator frame 1 along the axial direction, and reserving suitable threaded holes as cable connection points 51 at symmetrical locations on the left and right sides below the junction box 2 and end cover 3.

[0032] In one feasible implementation, the cross-sectional area of ​​the copper core in the grounding cable 4 is not less than 50 mm². 2 This ensures that it has sufficient current-carrying capacity to meet the discharge of common-mode current. Preferably, the grounding cable is made of flexible multi-strand copper braided tape, which has good conductivity and bending resistance.

[0033] Example 3 A method for preventing electro-corrosion in a semi-direct drive gearbox, using the structure for preventing electro-corrosion in a semi-direct drive gearbox described in any one of the embodiments of Examples 1-2, and the specific method is as follows.

[0034] A conductive element 5 with multiple cable connection points 51 is installed at the grounding point of the engine compartment. Each cable connection point 51 on the conductive element 5 is connected to the stator frame 1, junction box 2 and end cover 3 of the semi-direct drive generator through at least one grounding cable 4. Install carbon brush 7 next to hollow tube 6, make carbon brush 7 contact with the surface of hollow tube 6, and connect carbon brush 7 to the grounding point on the cabin through grounding cable 4.

[0035] Its specific effects are explained in detail in Example 1, therefore, they will not be elaborated upon in this example.

[0036] It should be noted that when installing the grounding cable 4 and conductive parts 5, the cable connection points 51 on the stator frame 1, junction box 2 and end cover 3, as well as the area around the grounding point on the nacelle, need to be cleaned to ensure that the contact surface is smooth and free of foreign objects, so as to ensure that the impedance at the connection is low and that the common mode current can be discharged through the grounding cable 4 to the maximum extent, thereby reducing the impact of common mode voltage on the electro-corrosion of the gearbox bearing.

[0037] Furthermore, when connecting the grounding cable 4 to the cable connection point 51 with bolts, 0.15-0.2mm of conductive paste can be evenly applied to all contact surfaces to ensure a firm connection and good contact, thereby reducing contact resistance.

[0038] Furthermore, when laying the grounding cable 4, the grounding cable 4 needs to be threaded through the appropriate corrugated pipe in advance, tied and fixed on the support along the path, kept straight during laying, and tied and fixed securely after laying for protection.

[0039] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A structure for preventing electro-corrosion in a semi-direct drive gearbox, characterized in that: Includes conductive components (5), carbon brushes (7), and multiple grounding cables (4), wherein: The conductive element (5) has multiple cable connection points (51), and the conductive element (5) is installed on the grounding point of the engine compartment; each cable connection point (51) on the conductive element (5) is connected to the stator frame (1), junction box (2) and end cover (3) of the semi-direct drive generator respectively through at least one grounding cable (4); The carbon brush (7) is mounted on and in contact with the hollow tube (6) of the semi-direct drive gearbox, and the carbon brush (7) is connected to the grounding point on the nacelle via the grounding cable (4).

2. The structure according to claim 1, characterized in that: Of any two adjacent cable connection points (51) on the conductive element (5), one connection point is closer to one side of the conductive element (5), and the other connection point is closer to the other side of the conductive element (5), and all cable connection points (51) are staggered along the length of the conductive element (5).

3. The structure according to claim 1, characterized in that: The carbon brush (7) is mounted on a bracket, which is mounted next to one end of the hollow tube (6), which is the end of the hollow tube (6) near the stator frame (1).

4. The structure according to claim 1, characterized in that: Cable connection points (51) are provided on the stator frame (1), junction box (2), end cover (3) and carbon brush (7), and the cable connection points (51) on the stator frame (1), junction box (2), end cover (3), carbon brush (7) and conductive component (5) are all connection holes.

5. The structure according to claim 4, characterized in that: Both ends of the grounding cable (4) are connected to grounding plates. The grounding plates are provided with connecting through holes. The screw in the bolt passes through the washer, connecting through hole, connecting hole and nut in sequence to connect the grounding cable (4) to the cable connection point (51).

6. The structure according to any one of claims 1-5, characterized in that: The cross-sectional area of ​​the copper core in the grounding cable (4) is not less than 50 mm². 2 .

7. A method for preventing electro-corrosion in a semi-direct drive gearbox, characterized in that: A conductive element (5) with multiple cable connection points (51) is installed at the grounding point of the engine compartment. Each cable connection point (51) on the conductive element (5) is connected to the stator frame (1), junction box (2) and end cover (3) of the semi-direct drive generator respectively through at least one grounding cable (4). Install carbon brushes (7) next to the hollow tube (6), make contact between the carbon brushes (7) and the surface of the hollow tube (6), and connect the carbon brushes (7) to the grounding point on the cabin through the grounding cable (4).

8. The method according to claim 7, characterized in that: Of any two adjacent cable connection points (51) on the conductive element (5), one connection point is closer to one side of the conductive element (5), and the other connection point is closer to the other side of the conductive element (5).

9. The method according to claim 7, characterized in that: The carbon brush (7) is mounted on a bracket, which is mounted next to one end of the hollow tube (6), which is the end of the hollow tube (6) near the stator frame (1).

10. The method according to any one of claims 7-9, characterized in that: The cross-sectional area of ​​the copper core in the grounding cable (4) shall not be less than 50 mm². 2 .

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