Large-current high-voltage dry-type direct-current support capacitor

Abstract

The invention discloses a large-current high-voltage dry-type direct-current support capacitor, which comprises a shell, a core, an electrical connection assembly, a wiring terminal assembly, an insulation assembly, filled resin, a pressure relief valve and a pressure switch, and is characterized in that the shell comprises a shell body, a shell bottom, a shell cover and a mounting bar; the mounting piece comprises a mounting piece body and a mounting nut, the core comprises an element, a first wire outlet copper foil and a second wire outlet copper foil, the electrical connection assembly comprises an electrical connection insulating plate, a copper bus bar and a connecting wire, and the wiring terminal assembly comprises an insulator, a sealing ring, a conducting rod and a fixing nut. The insulating assembly comprises a bottom insulating part, a first insulating part, a second insulating part and a corner insulating part. The device is simple in structure, is convenient to install and use, and can meet the requirements of long-term safe, stable and reliable operation of the DC support capacitor.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of capacitors, and particularly relates to a large-current high-voltage dry-type direct-current support capacitor. BACKGROUND

[0002] The direct-current support capacitor is a key device of a converter, and mainly plays a role of stabilizing voltage and filtering. At present, the dry-type direct-current support capacitor is widely used in the fields of new energy, rail transit and smart grid. With the development of power electronic technology, the power of the converter is getting larger and larger, and the current resistance of the direct-current support capacitor needs to be stronger. Especially, the current of the direct-current support capacitor applied to the high-power frequency converter and STATCOM is generally large, and the maximum current of 2.8kV / 8mF has reached 1000A.

[0003] Such direct-current support capacitor with large current has large heat power, and the temperature of the internal core is large, which will greatly reduce the service life in long-term operation. Such capacitor also has the commonness of dry-type structure, high voltage, large capacity and large weight. Therefore, the heat and heat dissipation factors need to be considered at the same time.

[0004] At present, the dry-type direct-current support capacitor is divided into multiple cores inside, and the whole copper bar for connecting the cores can reduce the heat power, which is composed of a welded copper bar, a poured resin and a shell to comprehensively dissipate heat. Such capacitor has relatively large weight, and needs to be installed and fixed on the frame or the support of the device, usually adopting 304 stainless steel plate. Considering the combination firmness of the resin and the stainless steel plate, high-viscosity and low-density flame-retardant polyurethane is usually adopted. Usually, the thermal conductivity coefficient of the high-viscosity and low-density flame-retardant polyurethane after curing is 0.2W / m•K, and the thermal conductivity coefficient of the 304 stainless steel plate is 16W / m•K.

[0005] The capacitor structure can reduce the heat power of the capacitor, thereby reducing the temperature of the internal core of the capacitor.

[0006] At present, multiple cores or capacitor units are adopted inside the direct-current capacitor, which will increase the plating surface of the core element and increase the manufacturing cost. Similarly, the whole copper bar welding of the core of the direct-current capacitor also increases the manufacturing cost of the capacitor. The whole copper bar butt welding of the core of the direct-current capacitor has very high requirements for the welding force and accuracy, and the phenomenon of incomplete welding may occur, which needs the inspector to spend more time for inspection. In addition, in the core welding process, if the element is damaged, the replacement is relatively cumbersome. Therefore, the production efficiency is relatively low.

[0007] The capacitor with the above structure can also solve the problems of heat dissipation, insulation and large current resistance by adopting the capacitor multi-core and whole copper bar structure, but also has respective shortcomings.

[0008] In summary, the high-voltage large-current dry-type DC support capacitor needs to consider: heat power; internal insulation structure; heat dissipation structure; production cost and efficiency. Solving these key technologies becomes the key point to be overcome in the research and development of such capacitors. SUMMARY

[0009] In order to overcome the shortcomings of the existing DC support capacitor electrode structure technology, the application provides a large-current high-voltage dry-type DC support capacitor (hereinafter referred to as "capacitor").

[0010] The technical scheme adopted by the application is as follows.

[0011] The capacitor comprises a shell, a core, an electrical connection assembly, a terminal assembly, an insulation assembly, a filled resin, a pressure release valve and a pressure switch. The shell comprises a shell body, a shell bottom, a shell cover and a mounting bar. The mounting bar comprises a mounting bar body and a mounting nut. The core comprises an element, a first outgoing copper foil and a second outgoing copper foil. The electrical connection assembly comprises an electrical connection insulation plate, a copper bus and a connecting wire. The terminal assembly comprises an insulator, a sealing ring, a conductive rod and a fixing nut. The insulation assembly comprises a bottom insulation piece, a first insulation piece, a second insulation piece and a corner insulation piece.

[0012] The first outgoing copper foil of the core is welded at both end faces of the element, and the second outgoing copper foil is folded L-shaped after being welded together with the first outgoing copper foil, and then welded together with the connecting wire of the electrical connection assembly. The other end of the connecting wire is welded together with the copper bus.

[0013] The insulator is placed on the upper end of the sealing ring, the lower end of the sealing ring is in the hole of the shell cover and is sealed with sealing glue, the upper end of the conductive rod is placed in the hole of the upper end of the insulator, and the lower end of the conductive rod passes through the copper bus, the electrical connection insulation plate and the sealing ring in turn and is fastened with the fixing nut.

[0014] The bottom insulation piece of the insulation assembly is placed between the core and the shell bottom, the first insulation piece is placed between the first outgoing copper foil and the second outgoing copper foil of the core and the shell body, the second insulation piece is placed between the element of the core and the shell body, and the corner insulation piece is placed at the four corners of the element of the core. The filled resin comprises resin filled in the gap between the core, the gap between the core and the insulation assembly, and the gap between the insulation assembly and the shell. The pressure release valve and the pressure switch are installed on the shell cover of the capacitor.

[0015] The shell adopts a 430 stainless steel plate, the thickness of the shell body is 2mm, and the thickness of the shell bottom, the shell cover and the mounting bar is 3mm.

[0016] The element adopts a cylindrical shape, is wound by two layers of metallized film on a core rod, and has a gold plating layer at both ends, and has a local breakdown self-healing performance.

[0017] The first outgoing copper foil material is brass, and its thickness is 1mm; the second outgoing copper foil material is brass, and its thickness is 1mm.

[0018] The electrically connected insulating plate is made of 2mm-thick epoxy plate, and has three square holes with a length of 17mm. The bus copper bar material is brass, and its thickness is 1mm, and its surface is tin-plated. The edge angle is chamfered with a diameter of 5mm, and has three square holes with a length of 17mm. The connecting wire is made of 35m 2 of copper wire.

[0019] The insulator is made of SMC composite material, and has a groove at the top, a convex groove at the bottom, and an inner hole in the middle.

[0020] The conductive rod is made of brass, and has a cylindrical outer thread structure at the upper end, a middle stepped cylinder, a lower end part of a light rod, and a square bottom. The outer surface is tin-plated.

[0021] The fixing nut is made of brass, and has an inner hole in the middle, an inner thread, and a nickel-plated outer surface.

[0022] The bottom insulating part is made of a 3mm-thick polyurethane block.

[0023] The first insulating part is made of polyurethane pouring, and has a thickness of 3mm, a plurality of circular holes with a diameter of 10mm, and a mixed ratio of A:B material of 20:100. The density is 1.5g / cm 3 , and the flame-retardant level is V0 level.

[0024] The second insulating part is made of polyurethane pouring, and has a thickness of 3mm, a plurality of circular holes with a diameter of 10mm, and a mixed ratio of A:B material of 20:100. The density is 1.5g / cm 3 , and the flame-retardant level is V0 level.

[0025] The edge angle insulating part is made of DMD paper and folded into an L shape.

[0026] The filled resin is made of polyurethane, and has a mixed ratio of A:B material of 40:100. The density is 0.92g / cm 3 , and the flame-retardant level is V0 level.

[0027] Further, the bus copper bar has one folded edge, and the bus copper bar and the connecting wire are welded at the folded edge.

[0028] Further, the first insulating part and the first insulating part are made of high-density polyurethane pouring, and the thermal conductivity coefficient after curing reaches 0.6W / m•K; the thermal conductivity coefficient of the 430 stainless steel plate reaches 40W / m•K; the element is welded with the first outgoing copper foil and then welded with the second outgoing copper foil, which not only reduces the resistance loss of the capacitor, but also increases the heat dissipation area of the core.

[0029] Through test verification, the temperature rise of the capacitor with the new structure of the rated current 1000A is reduced by about 30% than that of the conventional structure, which greatly reduces the operation temperature.

[0030] The capacitor has the advantages of good heat dissipation performance, good insulation performance and the like, solves the internal heat dissipation problem of the capacitor, reduces the production cost of the capacitor, and improves the production efficiency, operation reliability and service life of the capacitor.

[0031] The capacitor has the advantages of simple structure, convenient installation and use, and can meet the requirements of long-term safety, stability and reliable operation of the DC support capacitor. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic diagram for implementing the present application; Figure 2 is a top view of Figure 1 ; Figure 3 is a left view of Figure 1 ; Figure 4 is a front view of the longitudinal section structure of Figure 1 ; Figure 5 is a top view of the longitudinal section structure of Figure 1 ; Figure 6 is a left view of the longitudinal section structure of Figure 1 ; Figure 7 is a schematic diagram of part of the electrical connection assembly; Figure 8 is a schematic diagram of part of the insulation assembly; In the figure, 1 is an outer shell; 2 is a core; 3 is an electrical connection assembly; 4 is a wiring terminal assembly; 5 is an insulation assembly; 6 is filled resin; 7 is a pressure release valve; 8 is a pressure switch; 11 is a shell; 12 is a shell bottom; 13 is a shell cover; 14 is a mounting claw; 21 is an element; 22 is a first outgoing copper foil; 23 is a second outgoing copper foil; 31 is an electrical connection insulation plate; 32 is a bus copper bar; 33 is a connecting wire; 41 is an insulator; 42 is a sealing ring; 43 is a conductive rod; 44 is a fixing nut; 51 is a bottom insulation piece; 52 is a first insulation piece; 53 is a second insulation piece; 54 is a corner insulation piece; 141 is a mounting claw body; 142 is a mounting nut. DETAILED DESCRIPTION

[0033] The application will be further described in conjunction with the accompanying drawings and specific embodiments.

[0034] As can be seen from Figures 1-8 The capacitor comprises a shell (1), a core (2), an electrical connection assembly (3), a terminal assembly (4), an insulation assembly (5), a filled resin (6), a pressure release valve (7) and a pressure switch (8). The shell (1) comprises a shell body (11), a shell bottom (12), a shell cover (13) and a mounting lug (14), the mounting lug (14) comprises a mounting lug body (141) and a mounting nut (142), the core (2) comprises an element (21), a first copper foil (22) and a second copper foil (23), the electrical connection assembly (3) comprises an electrical connection insulation plate (31), a copper bus (32) and a connecting wire (33), the terminal assembly (4) comprises an insulator (41), a sealing ring (42), a conductive rod (43) and a fixing nut (44), and the insulation assembly (5) comprises a bottom insulation piece (51), a first insulation piece (52), a second insulation piece (53) and a corner insulation piece (54). The first copper foil (22) of the core (2) is welded on both end faces of the element (21), the second copper foil (23) is folded L-shaped after being welded with the first copper foil (21) and then welded with the connecting wire (33) of the electrical connection assembly (3), and the other end of the connecting wire (33) is welded with the copper bus (32). The insulator (41) is placed on the upper end of the sealing ring (42), the lower end of the sealing ring (42) is in the hole of the shell cover (13) and sealed with sealing glue, the upper end of the conductive rod (43) is placed in the hole of the insulator (41), and the lower end of the conductive rod (43) is sequentially passed through the copper bus (32), the electrical connection insulation plate (31) and the sealing ring (42) and fastened with the fixing nut (44). The bottom insulation piece (51) of the insulation assembly (5) is placed between the core (2) and the shell bottom (12), the first insulation piece (52) is placed between the first copper foil (22) and the second copper foil (23) of the core (2) and the shell body (11), the second insulation piece (53) is placed between the element (21) of the core (2) and the shell body (11), the corner insulation piece (54) is placed on the four corners of the element (21) of the core (2), the filled resin (6) comprises resin filled in the gap between the core (2), the gap between the core (2) and the insulation assembly (5), the gap between the insulation assembly (5) and the shell (1), and the pressure release valve (7) and the pressure switch (8) are installed on the capacitor shell cover (13).

[0035] The shell (1) is made of a 430 stainless steel plate, the thickness of the shell body (11) is 2 mm, and the thickness of the shell bottom (12), the shell cover (13) and the mounting lug (14) is 3 mm.

[0036] The element (21) is in the shape of a cylinder, is wound by two layers of metallized film on a mandrel, and has a gold-plated layer at both ends, and has the performance of self-healing after partial breakdown.

[0037] The first outgoing copper foil (22) is made of brass and has a thickness of 1 mm; the second outgoing copper foil (23) is made of brass and has a thickness of 1 mm.

[0038] The electrically connected insulating plate (31) is made of an epoxy plate with a thickness of 2 mm and has three square holes with a length of 17 mm; the bus copper bar (32) is made of brass and has a thickness of 1 mm, is surface-tinned, has a round corner chamfer with a diameter of 5 mm at the edge, and has three square holes with a length of 17 mm; the connecting wire (33) is made of 35 m 2 of copper wire.

[0039] The insulator (41) is made of SMC composite material, has a groove at the top, a convex groove at the bottom, and an inner hole in the middle.

[0040] The conductive rod (43) is made of brass, has a cylindrical shape and an external thread structure at the upper end, a stepped cylinder in the middle, a partial light rod at the lower end, and a square shape at the bottom, and is surface-tinned.

[0041] The fixing nut (44) is made of brass, has an inner hole in the middle, is internally threaded, and is surface-nickel plated.

[0042] The bottom insulating part (51) is made of a polyurethane block with a thickness of 3 mm.

[0043] The first insulating part (52) is made of polyurethane pouring and has a thickness of 3 mm, has multiple circular holes with a diameter of 10 mm, and has a mixing ratio of A:B of 20:100, a density of 1.5 g / cm 3 , and a flame-retardant level of V0.

[0044] The second insulating part (53) is made of polyurethane pouring and has a thickness of 3 mm, has multiple circular holes with a diameter of 10 mm, and has a mixing ratio of A:B of 20:100, a density of 1.5 g / cm 3 , and a flame-retardant level of V0.

[0045] The edge and corner insulating part (54) is made of DMD paper and is folded into an L shape.

[0046] The filled resin (6) is made of polyurethane, has a mixing ratio of A:B of 40:100, a density of 0.92 g / cm 3 , and a flame-retardant level of V0.

[0047] Further, the bus copper bar (32) has one folded edge, and the bus copper bar (32) and the connecting wire (33) are welded at the folded edge.

[0048] Further, the first insulation member (52) and the first insulation member (53) are made of high-density polyurethane and have a heat conductivity of 0.6 W / m•K after curing; the heat conductivity of the 430 stainless steel plate is 40 W / m•K; and the element (21) is welded with the second outgoing copper foil (23) after being welded with the first outgoing copper foil (22), which not only reduces the resistance loss of the capacitor, but also increases the heat dissipation area of the core (2).

[0049] Through test verification, the temperature rise of the capacitor with the new structure is reduced by about 30% compared with the conventional structure, and the operating temperature is greatly reduced.

[0050] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high-current, high-voltage dry-type DC supported capacitor, characterized in that: The high-current, high-voltage dry-type DC supported capacitor includes a shell, a core, an electrical connection assembly, a terminal assembly, an insulating assembly, a filled resin, a pressure relief valve, and a pressure switch. The shell includes a housing, a bottom, a cover, and a mounting plate. The mounting plate includes a mounting plate body and a mounting nut. The core includes an element, a first lead copper foil, and a second lead copper foil. The electrical connection assembly includes an electrical connection insulating plate, a busbar, and connecting wires. The terminal assembly includes an insulator, a sealing ring, a conductive rod, and a fixing nut. The insulating assembly includes a bottom insulating component, a first insulating component, a second insulating component, and corner insulating components. The first copper foil of the core is welded to both ends of the component. The upper end of the second copper foil and the first copper foil after being welded together is folded into an L-shape and then welded to the connecting wire of the electrical connection assembly. The other end of the connecting wire is welded to the busbar. The insulator is placed on the upper end of the sealing ring, the lower end of the sealing ring is inside the hole of the shell cover and sealed with sealant, the upper end of the conductive rod is placed inside the hole at the upper end of the insulator, and the lower end of the conductive rod passes through the busbar, the electrical connection insulation plate and the sealing ring in sequence and is fastened with a fixing nut. The bottom insulating component of the insulating assembly is placed between the core and the bottom of the shell. The first insulating component is placed between the first and second copper foils of the core and the shell. The second insulating component is placed between the core element and the shell. The corner insulating components are placed at the four corners of the core element. The filling resin includes resin for the gaps between cores, the gaps between the core and the insulating assembly, and the gaps between the insulating assembly and the shell. The pressure relief valve and pressure switch are installed on the capacitor shell cover.

2. The high-current, high-voltage dry-type DC supported capacitor according to claim 1, characterized in that: The outer shell is made of 430 stainless steel plate, the thickness of the shell is 2mm, and the thickness of the shell bottom, shell cover and mounting plate is 3mm.

3. The high-current, high-voltage dry-type DC supported capacitor according to claim 1, characterized in that: The first outgoing copper foil is made of brass and has a thickness of 1 mm; the second outgoing copper foil is made of brass and has a thickness of 1 mm.

4. The high-current, high-voltage dry-type DC supported capacitor according to claim 1, characterized in that: The busbar is made of brass with a thickness of 1mm and a tin-plated surface. The rounded corners have a diameter of 5mm and the busbar has three square holes with a length of 17mm.

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