Power conversion device

Abstract

A power conversion device. In the power conversion device of the application, the shell of the bus capacitor is exposed to the external environment relative to the outer shell, greatly reducing the influence of heat generation of other heat generating devices in the power conversion device on the bus capacitor. The heat generated by the bus capacitor can be quickly dissipated to the external environment without passing through the outer shell, improving the heat dissipation effect of the bus capacitor and effectively reducing the risk of failure of the bus capacitor due to electrolyte evaporation and drying. When the external bus capacitor explodes due to overheating, the electrolyte inside the bus capacitor will not be sprayed into the internal part of the power conversion device, avoiding the spread of failure. The plurality of positive pole foils, the plurality of negative pole foils and the electrolyte of the bus capacitor are stacked to form a laminated structure. The ratio of the surface area to the volume of the laminated bus capacitor is higher than that of the cylindrical bus capacitor, and the heat generated by the laminated bus capacitor is more easily dissipated to the external environment from the larger surface.

Description

Technical Field

[0001] This application relates to the field of photovoltaic power generation technology, and in particular to a power conversion device. Background Technology

[0002] Among various bus capacitors, aluminum electrolytic capacitors have the advantages of high capacitance density and low price, and are widely used in power conversion devices. Generally speaking, aluminum electrolytic capacitors specifically refer to liquid aluminum electrolytic capacitors, whose internal structure includes positive aluminum foil, negative aluminum foil, electrolytic paper, electrolyte, electrode leads, casing, and other auxiliary structures. Bus capacitors used in power conversion devices generate significant heat under the influence of ripple current. Excessively high temperatures accelerate the evaporation and drying of the electrolyte, leading to capacitor failure. Utility Model Content

[0003] This application provides a power conversion device that can improve the heat dissipation effect of the bus capacitor and reduce the risk of bus capacitor failure.

[0004] This application provides a power conversion device for converting direct current (DC) from photovoltaic modules or energy storage batteries into alternating current (AC) and transmitting the AC power to the power grid. The power conversion device includes a housing, a circuit board, and a bus capacitor. The housing houses the circuit board, which in turn holds the bus capacitor. The bus capacitor regulates the DC power from the photovoltaic modules or energy storage batteries and includes a housing, multiple positive electrode foils, multiple negative electrode foils, electrolytic paper, and electrode connectors. The housing is located outside the main housing and houses the multiple positive electrode foils, multiple negative electrode foils, and electrolytic paper. The multiple positive electrode foils are stacked, with a negative electrode foil between adjacent positive electrode foils. The electrolytic paper, impregnated with electrolyte, is placed between the positive and negative electrode foils. The positive leads of the multiple positive electrode foils and the negative leads of the multiple negative electrode foils are connected to the electrode connectors. The electrode connectors pass through the housing and connect to the circuit board.

[0005] In this application, the casing of the bus capacitor is exposed to the external environment relative to the outer casing, greatly reducing the impact of heat generated by other heat-generating components within the power conversion device on the bus capacitor. The heat generated by the bus capacitor can be quickly dissipated to the external environment without needing to pass through the outer casing, improving the heat dissipation effect of the bus capacitor and effectively reducing the risk of failure due to electrolyte evaporation and drying. In the event of an explosion caused by overheating of the external bus capacitor, the electrolyte inside the bus capacitor will not be sprayed into the power conversion device, preventing the spread of failure.

[0006] Furthermore, the multiple positive and negative electrode foils and electrolyte layers of the bus capacitor are stacked to form a laminated structure. The surface area to volume ratio of the laminated bus capacitor is higher than that of the cylindrical bus capacitor, allowing heat generated by the laminated structure to be more easily dissipated to the external environment from its larger surface area. In scenarios with multiple bus capacitors, the laminated structure facilitates dense arrangement and improves space utilization on the exterior of the casing.

[0007] In one possible implementation, the power conversion device further includes a protective cover, which is located outside the housing and is fixedly connected to the housing. The protective cover houses the bus capacitor and has multiple ventilation holes that connect the interior and exterior of the protective cover.

[0008] A protective cover is installed on the outside of the power conversion device to protect the exposed bus capacitors from impact. Multiple ventilation holes in the cover connect the interior of the cover to the external environment, allowing heat generated by the bus capacitors to be dissipated into the external environment through these holes.

[0009] In one possible implementation, the positive electrode foil has sheet-shaped positive tabs, and the positive tabs of multiple positive electrode foils are connected and fixed to form a positive electrode pin. The negative electrode foil has sheet-shaped negative electrode tabs, and the negative electrode tabs of multiple negative electrode foils are connected and fixed to form a negative electrode pin.

[0010] In a traditional design, the cylindrical positive tab is connected to a point on the positive foil, and similarly, the negative tab is connected to a point on the negative foil. The small contact area between the positive and negative tabs and the foils forces current to converge onto a small cross-section, resulting in a high overall equivalent series resistance (ESR). In this application, the sheet-like positive tab has a wider contact surface with the positive foil, and the negative tab has a wider contact surface with the negative foil. This allows current to flow dispersedly through the entire contact surface into either the positive or negative tab, significantly reducing the contact resistance between the positive foil and the positive tab, and between the negative tab and the negative foil, thereby lowering the overall ESR of the bus capacitor.

[0011] In one possible implementation, the electrode connector includes a connecting plate and a connecting post. The connecting plate is housed within a housing. The connecting plate corresponding to the positive electrode pin is stacked on one side of the positive electrode pin and connected and fixed to the positive electrode pin. The connecting plate corresponding to the negative electrode pin is stacked on one side of the negative electrode pin and connected and fixed to the negative electrode pin. One end of the connecting post is connected to the connecting plate, and the other end of the connecting post passes through the housing and outer shell and is connected to the circuit board.

[0012] When connecting the positive pin to the corresponding connector, the side with the larger positive tab can be placed on top of the side with the larger positive tab on the corresponding connector, creating a large contact area between the positive tab and the corresponding electrode connector, thereby reducing the contact resistance between them. Similarly, when connecting the negative pin to the corresponding connector, the side with the larger negative tab can be placed on top of the side with the larger negative tab on the corresponding connector, creating a large contact area between the negative tab and the corresponding electrode connector, thus reducing the contact resistance between them. This large contact area between both the positive and negative tabs ensures a more even distribution of current at the connection points, preventing additional resistance caused by excessively high local current density.

[0013] The connecting post needs to pass through the housing of the bus capacitor and the outer shell of the power conversion device to connect with the circuit board. The columnar structure of the connecting post can reduce the opening area on the housing and the outer shell, ensuring the sealing of the bus capacitor and the power conversion device.

[0014] In one possible implementation, the housing further includes a protrusion that protrudes from the outer surface of the housing. The power conversion device also includes multiple latches located on the outer surface of the housing facing the housing. Each latch has a hook that abuts against the side of the protrusion facing away from the housing. The bus capacitor is mounted on the housing using these latches, with the latches directly abutting against the surface of the protrusion, simplifying the installation of the bus capacitor.

[0015] In one possible implementation, the housing further includes multiple protrusions spaced apart on the outer peripheral surface of the housing, each protrusion having a limiting hole. The power conversion device also includes multiple latches corresponding to the protrusions, located on the outer surface of the housing facing the housing. Each latch has a hook, at least a portion of which passes through the limiting hole and engages with the protrusion. The bus capacitor is mounted on the housing by means of latches, and the protrusions have limiting holes that engage with the hooks of the latches, enhancing the stability of the housing installation.

[0016] In one possible implementation, the power conversion device further includes a metal connection bar housed inside the housing, the metal connection bar being disposed on the side of the circuit board facing the housing, and the metal connection bar being connected to the circuit board and the electrode connectors.

[0017] After the metal connector is connected and fixed to the electrode connector, it can fix the bus capacitor. Furthermore, the metal connector is fixed to the circuit board, and the electrode connector achieves electrical connection with the circuit board through the metal connector. The supporting force for the bus capacitor is provided by the metal connector, which reduces the stress on the circuit board to a certain extent.

[0018] In one possible implementation, the electrode connector inside the housing has threaded holes. The power conversion device also includes fasteners housed inside the housing, with metal connecting strips passing through and connecting to the threaded holes.

[0019] A threaded hole is provided on the electrode connector. After the fastener passes through the metal connecting strip, it is connected to the threaded hole. When the fastener is connected to the threaded hole, only the fastener needs to be rotated to be connected and fixed. The metal connecting strip will not rotate inside the housing. In this way, when the fastener is connected to the electrode connector, it will not affect other components inside the power conversion device.

[0020] In one possible implementation, the positive and negative leads are staggered on the outer edge of the electrolytic paper, and are located on the same side of the electrolytic paper. This staggered arrangement prevents excessive localized temperature rise due to concentrated AC density, thus ensuring the lifespan of the bus capacitor. When the positive and negative leads are led out from the same side, the sides containing the positive and negative leads can be mounted and fixed towards the outer casing, shortening the length of the electrode connectors. The distance between the other sides of the multiple positive and negative electrode foils and the corresponding sidewalls of the casing is also smaller, improving space utilization and shortening the thermal link between the multiple electrode foils and the casing.

[0021] In one possible implementation, the housing has a mounting through-hole and a groove, wherein the mounting through-hole is for inserting an electrode connector, and the groove is located on the outer periphery of the mounting through-hole. The power conversion device also includes a seal located in the groove, the seal abutting between the housing and the outer casing.

[0022] A seal is installed around the mounting hole. The pressure applied when the bus capacitor is fixed to the circuit board can press the seal tightly between the housing and the outer shell. The exposed electrode connectors are enclosed by the seal. Even with the bus capacitor exposed to the external environment, this maintains a energized seal on the exposed electrode connectors, reducing the possibility of short circuits in the event of water spray or contact with foreign objects. Furthermore, the seal is housed within a groove, allowing the bus capacitor's housing to fit tightly against the outer surface of the outer shell when mounted. This extends the path for external moisture or foreign objects to enter the seal, improving the sealing performance at the electrode connectors. Simultaneously, it prevents external moisture and debris from entering the housing and the outer shell. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments of this application will be described below.

[0024] Figure 1 This is a schematic diagram of the architecture of an optical energy storage system provided in one embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the structure of a power conversion device provided in an embodiment of this application;

[0026] Figure 3 for Figure 2 A schematic cross-sectional view of the power conversion device shown along line III-III;

[0027] Figure 4 A schematic diagram of the layout of multiple bus capacitors in a power conversion device according to an embodiment of this application;

[0028] Figure 5 This is a schematic diagram of the structure of a bus capacitor provided in one embodiment of this application;

[0029] Figure 6 This is a partial structural schematic diagram of a bus capacitor provided in an embodiment of this application;

[0030] Figure 7 for Figure 5 The diagram shows the exploded structure of the bus capacitor.

[0031] Figure 8 A schematic diagram of the layout of the positive and negative pins provided in an embodiment of this application;

[0032] Figure 9 A schematic diagram of another layout of the positive and negative pins provided in an embodiment of this application;

[0033] Figure 10 This is a schematic diagram of another layout of the positive and negative pins provided in an embodiment of this application;

[0034] Figure 11 This is a schematic diagram of another layout of the positive and negative pins provided in an embodiment of this application;

[0035] Figure 12 This is a partial structural schematic diagram of a power conversion device provided in one embodiment of this application;

[0036] Figure 13 for Figure 12 The diagram shows an exploded view of the power conversion device.

[0037] Figure 14 for Figure 12 The front view of the power conversion device shown;

[0038] Figure 15 This is a partial structural schematic diagram of another power conversion device provided in an embodiment of this application;

[0039] Figure 16 for Figure 15The diagram shows an exploded view of the power conversion device.

[0040] Figure 17 A partial structural schematic diagram of another power conversion device provided in an embodiment of this application;

[0041] Figure 18 for Figure 17 The diagram shows an exploded view of the power conversion device.

[0042] Figure 19 This is a schematic diagram of the structure of another power conversion device provided in an embodiment of this application.

[0043] Explanation of reference numerals in the attached figures:

[0044] 10-Outer shell; 11-Mounting through hole; 12-Snap-on; 121-Hook; 20-Circuit board; 30-Bus capacitor; 31-Housing shell; 311-Bottom shell; 312-Cover plate; 313-Bump; 3131-Limiting hole; 32-Positive electrode foil; 321-Positive electrode pin; 322-Positive electrode tab; 33-Negative electrode foil; 331-Negative electrode pin; 332-Negative electrode tab; 34-Electrolytic paper; 35-Electrode connector; 35 1-Connecting plate; 352-Connecting post; 353-Threaded hole; 36-Seal; 40-Power module; 50-Metal connecting bar; 60-Fastener; 70-Protective cover; 71-Ventilation hole; 80-Fan; 100-Power conversion device; 101-Photovoltaic inverter; 102-Energy storage converter; 200-Photovoltaic module; 300-Box substation; 400-Step-up substation; 500-Grid; 600-Energy storage battery. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0046] Please see Figure 1 , Figure 1 This is a schematic diagram of the architecture of a photovoltaic energy storage system provided in one embodiment of this application. Figure 1As shown, the photovoltaic-storage system includes a photovoltaic system and an energy storage system. In the photovoltaic system, photovoltaic modules 200 convert solar energy into direct current (DC) through the photovoltaic effect. Each photovoltaic module 200 includes multiple cells connected in series or parallel to achieve a certain output power. A photovoltaic inverter 101 converts the DC power from the photovoltaic modules 200 into alternating current (AC), and then transmits the AC power to a corresponding prefabricated substation 300 for voltage transformation. The prefabricated substation 300 can convert the low-voltage AC power output from the photovoltaic inverter 101 into medium-voltage AC power, and then further transmit the AC power to a step-up substation 400 and then to the power grid 500 or other loads. Alternatively, it can further transmit the AC power to a prefabricated substation 300 corresponding to the energy storage converter 102.

[0047] In the energy storage system, the energy storage battery 600 is used to store the unstable electrical energy from the photovoltaic module 200, and provides stable electrical energy to the grid 500 or other loads through the energy storage converter 102 and the corresponding box-type substation 300. In addition, the energy storage converter 102 can also convert the AC power from the grid 500 into DC power to charge the energy storage battery 600 and store the electrical energy in the energy storage battery 600.

[0048] Figure 1 In the photovoltaic-storage system shown, the photovoltaic inverter 101 and the energy storage converter 102 are the core devices for power conversion, and they are collectively referred to as the power conversion device 100. The structure of the power conversion device 100 provided in this application will be described in detail below with reference to the accompanying drawings. It is worth mentioning that the power conversion device 100 provided in this application can be applied to residential photovoltaic systems, as well as to photovoltaic-storage systems in large-scale ground-mounted power plants or industrial and commercial applications.

[0049] This application provides a power conversion device 100 for converting alternating current (AC) and direct current (DC) into the other. In one embodiment, the power conversion device 100 may be a photovoltaic inverter 101. In this embodiment, the power conversion device 100 is applied in a photovoltaic system and is used to convert DC power from a photovoltaic module 200 into AC power and transmit the AC power to the power grid 500 or other loads.

[0050] In another embodiment, the power conversion device 100 may be an energy storage converter 102. In this embodiment, the power conversion device 100 is applied to an energy storage system. The power conversion device 100 is used to convert DC power from the energy storage battery 600 into AC power and deliver the AC power to the power grid 500 or other loads. In addition, the power conversion device 100 can also convert AC power from the power grid 500 into DC power to charge the energy storage battery 600.

[0051] Please see Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the structure of a power conversion device 100 provided in an embodiment of this application. Figure 3 for Figure 2 The diagram shows a cross-sectional view of the power conversion device 100 along line III-III. The power conversion device 100 includes a housing 10, a circuit board 20, and a bus capacitor 30. The housing 10 houses the circuit board 20. The circuit board 20 is used to fix the bus capacitor 30. The circuit board 20 can be a printed circuit board (PCB). The circuit board 20 may also house a power module 40, an inductor, a DC switch, and a relay. The power module 40 converts DC power from photovoltaic modules or energy storage batteries into AC power and transmits the AC power to the power grid. In one embodiment, the power module 40, inductor, DC switch, and relay can be disposed on the same surface of the circuit board 20. In another embodiment, at least one of the inductor, DC switch, and relay can be disposed on opposite sides of the circuit board 20, without specific limitation.

[0052] Please combine Figure 4 , Figure 4 This is a schematic diagram showing the layout of multiple bus capacitors 30 in a power conversion device 100 according to an embodiment of this application. The number of bus capacitors 30 can be multiple, and the multiple bus capacitors 30 are arranged in an array on the outside of the housing 10. There is a gap between adjacent bus capacitors 30 to facilitate heat dissipation.

[0053] Please combine Figure 5 and Figure 6 , Figure 5 This is a schematic diagram of the structure of a bus capacitor 30 provided in an embodiment of this application. Figure 6This is a partial structural schematic diagram of a bus capacitor 30 provided in an embodiment of this application. The bus capacitor 30 is used to regulate the DC power from a photovoltaic module or energy storage battery. After being regulated by the bus capacitor 30, the DC power from the photovoltaic module or energy storage battery is output to the power module 40, where the regulated DC power is converted into AC power. The bus capacitor 30 includes a housing 31, multiple positive electrode foils 32, multiple negative electrode foils 33, electrolytic paper 34, and electrode connectors 35. The housing 31 is located outside the outer casing 10 and is used to house the multiple positive electrode foils 32, multiple negative electrode foils 33, and electrolytic paper 34. The multiple positive electrode foils 32 are stacked, and a negative electrode foil 33 is disposed between two adjacent positive electrode foils 32. The electrolytic paper 34 is disposed between the positive electrode foils 32 and the negative electrode foils 33, and is impregnated with electrolyte. The positive leads 321 of the multiple positive electrode foils 32 and the negative leads 331 of the multiple negative electrode foils 33 are all connected to the electrode connector 35. The electrode connector 35 passes through the housing 10 and is connected to the circuit board 20.

[0054] In this application, the bus capacitor 30 is placed outside the housing 10 of the power conversion device 100, with the housing 31 of the bus capacitor 30 exposed to the external environment relative to the housing 10. This significantly reduces the impact of heat generated by other heat-generating components within the power conversion device 100 on the bus capacitor 30. Furthermore, the heat generated by the bus capacitor 30 can be quickly dissipated to the external environment without passing through the housing 10, improving the heat dissipation effect of the bus capacitor 30 and effectively reducing the risk of failure due to electrolyte evaporation and drying. In the event of an explosion caused by overheating of the external bus capacitor 30, the electrolyte inside the bus capacitor 30 will not be sprayed into the power conversion device 100, preventing the spread of failure. Simultaneously, the heat generated by the bus capacitor 30 has a minimal impact on the temperature inside the housing 10.

[0055] Furthermore, the multiple positive electrode foils 32, multiple negative electrode foils 33, and electrolyte of the bus capacitor 30 are stacked to form a laminated structure. The surface area to volume ratio of the laminated bus capacitor 30 is higher than that of the cylindrical bus capacitor 30, making it easier for the heat generated by the laminated bus capacitor 30 to dissipate to the external environment from its larger surface area. In scenarios with multiple bus capacitors 30, the laminated structure facilitates dense arrangement and improves space utilization outside the casing 10.

[0056] For example, the housing 31 is mounted on the outside of the outer casing 10. The housing 31 can be directly fixed to the outer casing 10 or fixed to the circuit board 20. The housing 31 sealably houses a plurality of positive electrode foils 32, a plurality of negative electrode foils 33, an electrolyte, and a portion of the electrode connector 35. The positive electrode leads 321 of the plurality of positive electrode foils 32 and the negative electrode leads 331 of the plurality of negative electrode foils 33 are also housed within the housing 31, reducing the possibility of short circuits between the positive and negative electrode leads 331 and the electrode connector 35 caused by external moisture or debris.

[0057] Please combine Figure 7 , Figure 7 for Figure 5 The diagram shows an exploded view of the bus capacitor 30. For example, the housing 31 includes a bottom shell 311 and a cover plate 312. The bottom shell 311 has an open receiving cavity that accommodates a plurality of positive electrode foils 32, a plurality of negative electrode foils 33, electrolytic paper 34, and a portion of the electrode connector 35. The cover plate 312 covers the opening of the bottom shell 311, and is fixedly connected to the bottom shell 311, ensuring a seal and insulation at the connection between the cover plate 312 and the bottom shell 311.

[0058] In this design, a portion of the electrode connector 35 passes through the cover plate 312 and the outer shell 10 and is connected to the circuit board 20. The electrode connector 35 is fitted into the cover plate 312. For example, after the positive electrode pin 321 is connected and fixed to the corresponding electrode connector 35, and the negative electrode pin 331 is connected and fixed to the corresponding electrode connector 35, the portion of the electrode connector 35 extending out of the shell 31 is fixed to the mold of the injection-molded cover plate 312. Then, the cover plate 312 is formed by injection molding in the mold, thereby achieving a sealed connection between the cover plate 312 and the electrode connector 35. External moisture or debris is not easily allowed to enter the receiving cavity.

[0059] Multiple positive electrode foils 32 and multiple negative electrode foils 33 can be aluminum foils. The positive electrode foils 32, negative electrode foils 33, and electrolytic paper 34 can all be rectangular in shape. Each positive electrode foil 32 has a sheet-like positive electrode tab 322. The positive electrode tabs 322 of multiple positive electrode foils 32 are connected and fixed to form a positive electrode pin 321. For example, the positive electrode tabs 322 are formed by extending the side of the positive electrode foil 32. The positive electrode foil 32 and the positive electrode tabs 322 are an integral structure, eliminating the soldering step of the positive electrode tabs 322 and reducing ESR. After each positive electrode foil 32 forms a positive electrode tab 322, the positive electrode tabs 322 of multiple positive electrode foils 32 are pressed together to form a positive electrode pin 321.

[0060] The negative electrode foil 33 is provided with sheet-like negative electrode tabs 332. The negative electrode tabs 332 of multiple negative electrode foils 33 are connected and fixed to form a negative electrode pin 331. For example, the negative electrode tabs 332 are formed by extending the side of the negative electrode foil 33. The negative electrode foil 33 and the negative electrode tabs 332 are an integral structure, eliminating the soldering step of the negative electrode tabs 332 and reducing ESR. After each negative electrode foil 33 forms a negative electrode tab 332, the negative electrode tabs 332 of multiple negative electrode foils 33 are pressed together to form a negative electrode pin 331.

[0061] The cylindrical positive tab 322 is connected to a point on the positive foil 32, and similarly, the negative tab 332 is connected to a point on the negative foil 33. The contact area between the positive and negative tabs 332 and the foil is small, forcing the current to converge onto a small cross-section, resulting in a high overall ESR. In this application, the contact surfaces between the sheet-like positive tab 322 and the positive foil 32, and between the negative tab 332 and the negative foil 33, are wider. Current can then flow dispersedly through the entire contact surface into either the positive tab 322 or the negative tab 332, significantly reducing the contact resistance between the positive foil 32 and the positive tab 322, and between the negative tab 332 and the negative foil 33, thereby reducing the overall ESR of the bus capacitor 30.

[0062] The positive terminal 321 and the negative terminal 331 are staggered on the outer edge of the electrolytic paper 34. This staggered arrangement of the positive terminal 321 and the negative terminal 331 on the outer edge of the electrolytic paper 34 can prevent excessive local temperature rise caused by concentrated AC density, thus ensuring the service life of the bus capacitor 30.

[0063] The positive electrode pin 321 and the negative electrode pin 331 are located on the same side of the electrolytic paper 34, wherein the electrolytic paper 34 has a rectangular structure and may include a long side and a short side.

[0064] Please see Figure 8 , Figure 8 This is a schematic diagram of the layout of the positive electrode pin 321 and the negative electrode pin 331 provided in one embodiment of this application. In one embodiment, the positive electrode pin 321 and the negative electrode pin 331 are both located on the same long side of the electrolytic paper 34. In this way, the positive electrode pin 321 and the negative electrode pin 331 are far apart, reducing the mutual influence between the positive and negative electrode pins 331.

[0065] Please see Figure 9 , Figure 9 This is a schematic diagram illustrating another layout of the positive electrode pin 321 and the negative electrode pin 331 provided in one embodiment of this application. In another embodiment, the positive electrode pin 321 and the negative electrode pin 331 may be disposed on the same short side of the electrolytic paper 34.

[0066] Specifically, the positive electrode tabs 322 of each positive electrode foil 32 are disposed on the same side of the electrolytic paper 34, in the stacking direction of the positive electrode foil 32 and the negative electrode foil 33 (e.g., Figure 8 or Figure 9 In the Z direction, the positive tabs 322 of two adjacent positive electrode foils 32 are arranged opposite each other, and then the positive tabs 322 of multiple positive electrode foils 32 are pressed together. The negative tabs 332 of each negative electrode foil 33 are arranged on the same side of the electrolytic paper 34. In the stacking direction of the positive electrode foils 32 and the negative electrode foils 33, the negative tabs 332 of two adjacent negative electrode foils 33 are arranged opposite each other, and then the negative tabs 332 of multiple negative electrode foils 33 are pressed together. When the positive electrode pin 321 and the negative electrode pin 331 are located on the same side of the electrolytic paper 34, the positive electrode foil 32 and the positive tab 322 are in an "L" shape, and the negative electrode foil 33 and the negative tab 332 are in an "L" shape. For example, the foil to be processed can be cut into an "L" shape to form the negative electrode foil 33 and the negative tab 332, or to form the positive electrode foil 32 and the positive tab 322. When the positive electrode pin 321 and the negative electrode pin 331 are led out on the same side, the sides where the positive electrode pin 321 and the negative electrode pin 331 are located can be installed and fixed towards the housing 10, which can shorten the length of the electrode connector 35. The distance between the other sides of the multiple positive electrode foils 32 and the multiple negative electrode foils 33 as a whole and the corresponding sidewall of the housing 31 is small, which improves the space utilization rate and shortens the thermal link from the multiple electrode foils and the multiple negative electrode foils 33 as a whole to the housing 31.

[0067] In other embodiments, the positive pin 321 and the negative pin 331 are located on different sides of the electrolytic paper 34.

[0068] Please see Figure 10 , Figure 10 This is a schematic diagram illustrating another layout of the positive electrode pin 321 and the negative electrode pin 331 provided in one embodiment of this application. In one embodiment, one of the positive electrode pin 321 and the negative electrode pin 331 is disposed on one of the long sides of the electrolytic paper 34, and the other of the positive electrode pin 321 and the negative electrode pin 331 is disposed on the other long side of the electrolytic paper 34. Specifically, the positive electrode tab 322 of each positive electrode foil 32 is disposed on one of the long sides of the electrolytic paper 34, and the negative electrode tab 332 of each negative electrode foil 33 is disposed on the other long side of the electrolytic paper 34.

[0069] Please see Figure 11 , Figure 11This is a schematic diagram illustrating another layout of the positive electrode pin 321 and the negative electrode pin 331 provided in one embodiment of this application. In another embodiment, one of the positive electrode pin 321 and the negative electrode pin 331 is disposed on one of the short sides of the electrolytic paper 34, and the other of the positive electrode pin 321 and the negative electrode pin 331 is disposed on the other short side of the electrolytic paper 34. Specifically, the positive electrode tab 322 of each positive electrode foil 32 is disposed on one of the short sides of the electrolytic paper 34, and the negative electrode tab 332 of each negative electrode foil 33 is disposed on the other short side of the electrolytic paper 34. In this way, the positive electrode pin 321 and the negative electrode pin 331 are relatively far apart, which can reduce the thermal impact between them.

[0070] When the positive electrode pin 321 and the negative electrode pin 331 are located on different sides of the electrolytic paper 34, the sides of the electrolytic paper 34 that do not have the positive electrode pin 321 and the negative electrode pin 331 can be installed facing the outer casing 10. For example, Figure 10 The multiple positive electrode foils 32 shown are mounted with their short sides facing the housing 10. Also, for example, [the following is an example of...]. Figure 9 The multiple positive electrode foils 32 shown are mounted with their long sides facing the outer casing 10. Among them, the electrode connectors 35 connecting the positive electrode pin 321 and the negative electrode pin 331 are located on opposite sides of the electrolytic paper 34. One end of the electrode connector 35 passes through the cover plate 312 and the outer casing 10 and is connected to the circuit board 20. With this installation, the electrode connector 35 does not need to be bent.

[0071] The bus capacitor 30 is processed as follows: The prepared positive electrode foil 32 and negative electrode foil 33 are cut into predetermined shapes (such as rectangles or "L" shapes). The positive electrode foil 32 and negative electrode foil 33 serve as the charge storage area and the electrode tab area, respectively. Electrolytic paper 34 covers the charge storage area. The electrode tab area of ​​the positive electrode foil 32 is the positive electrode tab 322, and the electrode tab area of ​​the negative electrode foil 33 is the negative electrode tab 332. Then, the multiple layers of cut positive electrode foil 32, negative electrode foil 33, and electrolyte-impregnated electrolytic paper 34 are stacked sequentially, with the positive electrode tab 322 of the positive electrode foil 32 and the negative electrode tab 332 of the negative electrode foil 33 staggered. The stacked positive electrode foil 32, multiple negative electrode foil 33, and electrolytic paper 34 are arranged as follows: Figure 8 , Figure 9 , Figure 10 and Figure 11 As shown. Then, the positive tabs 322 of multiple positive electrode foils 32 are connected together by welding or other methods to form a positive electrode pin 321, and the negative tabs 332 of multiple negative electrode foils 33 are connected together to form a negative electrode pin 331, as shown. Figure 6As shown, an electrode connector 35 is connected to one end of the positive pin 321 and another electrode connector 35 is connected to one end of the negative pin 331, forming the core of the bus capacitor 30. This core is assembled with the housing 31, and the exposed electrode connectors 35 are sealed and insulated for protection, thus forming a complete thin-film bus capacitor 30. In scenarios with multiple bus capacitors 30, the flow resistance between adjacent bus capacitors 30 is small, which is beneficial for heat dissipation.

[0072] Please return to the reference. Figure 7 , Figure 10 and Figure 11The electrode connector 35 can be made of the same material as the positive electrode pin 321 and the negative electrode pin 331. For example, the positive electrode pin 321, the negative electrode pin 331, and the electrode connector 35 can all be made of aluminum. The electrode connector 35 includes a connecting plate 351 and a connecting post 352. The connecting plate 351 is housed within the housing 31. The connecting plate 351 corresponding to the positive electrode pin 321 is stacked on one side of the positive electrode pin 321 and connected and fixed to the positive electrode pin 321. The connecting plate 351 corresponding to the negative electrode pin 331 is stacked on one side of the negative electrode pin 331 and connected and fixed to the negative electrode pin 331. When the positive electrode pin 321 is connected to the corresponding connecting plate 351, the side with the larger area of ​​the positive electrode tab 322 can be placed on the side with the larger area of ​​the corresponding connecting plate 351, so that the positive electrode tab 322 and the corresponding electrode connector 35 form a large-area contact, thereby reducing the contact resistance between the positive electrode tab 322 and the corresponding electrode connector 35. When the negative pin 331 is connected to the corresponding connecting plate 351, the larger side of the negative tab 332 can be stacked on the larger side of the corresponding connecting plate 351, so that the negative tab 332 and the corresponding electrode connector 35 form a large-area contact, thereby reducing the contact resistance between the negative tab 332 and the corresponding electrode connector 35. Both the positive tab 322 and the negative tab 332 form a large-area contact, so that the current is more evenly distributed at the connection between the positive tab 322 and the corresponding electrode connector 35, and at the connection between the negative tab 332 and the corresponding electrode connector 35, avoiding the additional resistance caused by excessive local current density. One end of the connecting post 352 is connected to the connecting plate 351. For example, the other end of the connecting post 352 is stacked on the side of the connecting plate 351 away from the positive pin 321 or the negative pin 331, and the other end of the connecting post 352 passes through the housing 31 and the outer shell 10 and is connected to the circuit board 20. The connecting post 352 and the connecting plate 351 can be separate structures, connected and fixed by welding or other methods; alternatively, they can be an integral structure, reducing the welding steps between them. The connecting post 352 needs to pass through the housing 31 of the bus capacitor 30 and the outer shell 10 of the power conversion device 100 to connect to the circuit board 20. The columnar structure of the connecting post 352 can reduce the opening area on the housing 31 and the outer shell 10, ensuring the sealing of the bus capacitor 30 and the power conversion device 100.

[0073] For example, the housing 10 is provided with a mounting through hole 11 for inserting an electrode connector 35, such as a connecting post 352. The shape of the mounting through hole 11 is adapted to the shape of the connecting post 352.

[0074] Please see Figure 12 and Figure 13 , Figure 12This is a partial structural schematic diagram of a power conversion device 100 provided in an embodiment of this application. Figure 13 for Figure 12 The diagram shows an exploded view of the power conversion device 100. In one embodiment, the bus capacitor 30 further includes a sealing element 36, which is tightly fitted between the housing 31 and the outer casing 10. The sealing element 36 can be sleeved on the electrode connector 35 located between the housing 31 and the outer casing 10, that is, the sealing element 36 is located on the outer periphery of the mounting through hole 11. The sealing element 36 is a sealing ring made of insulating rubber, which achieves insulation and sealing of the electrode connector 35. By setting the sealing element 36 on the outer periphery of the mounting through hole 11, the pressure applied when the bus capacitor 30 is fixed to the circuit board 20 can press the sealing element 36 tightly between the housing 31 and the outer casing 10. The exposed part of the electrode connector 35 is wrapped by the sealing element 36. Under the premise that the bus capacitor 30 is exposed to the external environment, the exposed part of the electrode connector 35 is kept electrically sealed, reducing the possibility of short circuit in the event of water spray or contact with foreign objects.

[0075] For example, the housing 10 also has a groove on the outer periphery of the mounting through hole 11, which is used to accommodate the seal 36, wherein the seal 36 abuts against the housing 10 of the housing 31. With the seal 36 accommodated in the groove, when the bus capacitor 30 is mounted on the housing 10, the housing 31 of the bus capacitor 30 can fit tightly against the outer surface of the housing 10, extending the path for external moisture or foreign matter to enter the seal 36, which helps improve the sealing performance at the electrode connector 35. Simultaneously, it also prevents external moisture and debris from entering the housing 31 and the housing 10.

[0076] In one embodiment, the power conversion device 100 further includes a metal connection busbar 50 housed inside the housing 10. The metal connection busbar 50 is located on the side of the circuit board 20 facing the housing 31, and is connected to the circuit board 20 and the electrode connector 35. The metal connection busbar 50 is fixedly connected to the connecting post 352 of the electrode connector 35, and is also connected to the circuit board 20 to achieve electrical connection between the bus capacitor 30 and the circuit board 20. The metal connection busbar 50 can be a copper busbar. After the metal connection busbar 50 is fixedly connected to the electrode connector 35, it can fix the bus capacitor 30. Furthermore, the metal connection busbar 50 is fixedly connected to the circuit board 20, and the electrode connector 35 achieves electrical connection with the circuit board 20 through the transition of the metal connection busbar 50. The supporting force for the bus capacitor 30 is provided by the metal connection busbar 50, which reduces the stress on the circuit board 20 to a certain extent.

[0077] Please combine Figure 14 , Figure 14 for Figure 12The diagram shows a front view of the power conversion device 100. Further, the electrode connector 35 inside the housing 10 is provided with a threaded hole 353, as is the connecting post 352 located inside the housing 10. The power conversion device 100 also includes a fastener 60, which is housed inside the housing 10 and passes through a metal connecting strip 50 and connects to the threaded hole 353. The fastener 60 can be a screw. During the connection and fixation process between the fastener 60 and the metal connecting strip 50, a tensile force is applied to the electrode connector 35 towards the metal connecting strip 50, thereby achieving the function of pressing the sealing member 36.

[0078] A threaded hole 353 is provided on the electrode connector 35. After the fastener 60 passes through the metal connecting strip 50, it is connected with the threaded hole 353. There is no need to open a threaded hole on the metal connecting strip 50. When the fastener 60 is connected with the threaded hole 353, it is only necessary to rotate the fastener 60 to connect and fix it. The metal connecting strip 50 will not rotate inside the housing 10. In this way, when the fastener 60 is connected with the electrode connector 35, it will not affect other components inside the power conversion device 100.

[0079] Please see Figure 15 and Figure 16 , Figure 15 This is a partial structural schematic diagram of another power conversion device 100 provided in an embodiment of this application. Figure 16 for Figure 15 The diagram shows an exploded view of the power conversion device 100. In another embodiment, the housing 31 further includes a protrusion 313, which protrudes from the outer surface of the housing 31 and surrounds the outer edge of the bottom housing 311. For example, the protrusion 313 is a flat plate structure extending outward relative to the outer surface of the bottom housing 311. The protrusion 313 is located at the end of the bottom housing 311 near the outer housing 10. The side of the protrusion 313 facing the outer housing 10 can be flush with the side of the cover plate 312 facing the outer housing 10. When the housing 31 is assembled with the outer housing 10, the side of the protrusion 313 facing the outer housing 10 and the side of the cover plate 312 facing the outer housing 10 can fit against the outer surface of the outer housing 10. When the seal 36 is received in the groove, the protrusion 313 further extends the path of moisture or debris from the external environment to the seal 36, strengthening the sealing protection of the bus capacitor 30.

[0080] The power conversion device 100 also includes a plurality of snap fasteners 12, which are disposed on the outer surface of the housing 10 facing the housing 31. Each snap fastener 12 has a hook 121, which is disposed facing the protrusion 313 and abuts against the side of the protrusion 313 away from the housing 10. The snap fasteners 12 are elastic and can deform within a small range. When the bus capacitor 30 is installed on the housing 10, pressure is applied to the bus capacitor 30 to fasten the protrusion 313 into the hooks 121 of the plurality of snap fasteners 12. In this way, the bus capacitor 30 is fixedly installed on the housing 10 by the snap fasteners 12, and the snap fasteners 12 directly abut against the surface of the protrusion 313, which simplifies the installation method of the bus capacitor 30.

[0081] Please see Figure 17 and Figure 18 , Figure 17 This is a partial structural schematic diagram of another power conversion device 100 provided in an embodiment of this application. Figure 18 for Figure 17 The diagram shows an exploded view of the power conversion device 100. In another embodiment, the housing 31 further includes a plurality of protrusions 313, which are spaced apart on the outer peripheral surface of the housing 31. Each protrusion 313 has a limiting hole 3131, which is a through hole penetrating both opposite sides of the protrusion 313. The power conversion device 100 also includes a plurality of latches 12 corresponding to each of the protrusions 313. The latches 12 are disposed on the outer surface of the housing 10 facing the housing 31. Each latch 12 has a hook 121, at least a portion of which passes through the limiting hole 3131 and engages with the protrusion 313. The buckle 12 is elastic and can deform within a small range. When the bus capacitor 30 is installed on the housing 10, the limiting hole 3131 of the protrusion 313 is aligned with the hook 121 of the buckle 12. At the same time, ensure that the electrode connector 35 is aligned with the mounting through hole 11. Apply pressure to the bus capacitor 30 toward the housing 10 so that the hooks 121 of the multiple buckles 12 are fastened one by one into the corresponding limiting hole 3131. At this time, the sealing member 36 can be pressed between the housing 31 and the housing 10 to achieve a seal for the electrode connector 35. The bus capacitor 30 is installed on the housing 10 by means of the buckle 12, and the protrusion 313 has a limiting hole 3131 that engages with the hook 121 of the buckle 12, which enhances the installation stability of the housing 31 and the housing 10.

[0082] Please see Figure 19 , Figure 19This is a schematic diagram of the structure of another power conversion device 100 provided in an embodiment of this application. The power conversion device 100 also includes a protective cover 70, which is disposed outside the outer shell 10 and is fixedly connected to the outer shell 10. The protective cover 70 houses the bus capacitor 30 and has multiple ventilation holes 71 that connect the interior and exterior of the protective cover 70. For example, multiple ventilation holes 71 are provided on the side walls of opposite sides of the protective cover 70, which can form convective air inside the protective cover 70, which is beneficial for heat dissipation. Alternatively, multiple ventilation holes 71 are provided on multiple side walls of the protective cover 70 to achieve multi-faceted ventilation. The protective cover 70 is provided outside the power conversion device 100 to protect the exposed bus capacitor 30 from impact. Furthermore, the multiple ventilation holes 71 of the protective cover 70 connect the interior of the protective cover 70 to the external environment, and the heat generated by the bus capacitor 30 is dissipated to the external environment through the ventilation holes 71.

[0083] Furthermore, the power conversion device 100 may also include a fan 80, which is fixed to the housing 10 and housed within the protective cover 70. The fan 80 is located between the multiple bus capacitors 30 and the side wall of the protective cover 70. The arrangement of the fan 80 accelerates the airflow within the protective cover 70 and accelerates the heat dissipation of the bus capacitors 30.

[0084] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A power conversion device, characterized by, The power conversion device is used to convert direct current (DC) from photovoltaic modules or energy storage batteries into alternating current (AC), and to transmit the AC power to the power grid. It includes a casing, a circuit board, and a bus capacitor. The housing is used to house the circuit board, and the circuit board is used to fix the bus capacitor; The bus capacitor is used to regulate the DC power from the photovoltaic module or the energy storage battery. The bus capacitor includes a housing, multiple positive electrode foils, multiple negative electrode foils, electrolytic paper, and electrode connectors. The housing is located outside the outer shell and is used to house the multiple positive electrode foils, the multiple negative electrode foils, and the electrolytic paper. The multiple positive electrode foils are stacked, and a negative electrode foil is disposed between two adjacent positive electrode foils. The electrolytic paper is disposed between the positive electrode foils and the negative electrode foils and is impregnated with electrolyte. The positive electrode leads of the multiple positive electrode foils and the negative electrode leads of the multiple negative electrode foils are all connected to the electrode connectors. The electrode connectors pass through the outer shell and are connected to the circuit board.

2. The power conversion device of claim 1, wherein, The power conversion device also includes a protective cover, which is located outside the housing and is fixedly connected to the housing. The protective cover houses the bus capacitor and has multiple ventilation holes that connect the interior and exterior of the protective cover.

3. The power conversion device according to claim 1 or 2, characterized by, The positive electrode foil has sheet-shaped positive electrode tabs, and the positive electrode tabs of the plurality of positive electrode foils are connected and fixed to form the positive electrode pins. The negative electrode foil has sheet-shaped negative electrode tabs, and the negative electrode tabs of the plurality of negative electrode foils are connected and fixed to form the negative electrode pins.

4. The power conversion device of claim 3, wherein, The electrode connector includes a connecting plate and a connecting post. The connecting plate is housed within the housing. The connecting plate corresponding to the positive electrode pin is stacked on one side of the positive electrode pin and connected and fixed to the positive electrode pin. The connecting plate corresponding to the negative electrode pin is stacked on one side of the negative electrode pin and connected and fixed to the negative electrode pin. One end of the connecting post is connected to the connecting plate, and the other end of the connecting post passes through the housing and the outer shell and is connected to the circuit board.

5. The power conversion device according to any one of claims 1 to 4, characterized by, The housing also includes a protrusion that protrudes from the outer peripheral surface of the housing; The power conversion device further includes multiple latches, which are disposed on the outer surface of the housing facing the housing. Each latch has a hook that abuts against the side of the protrusion facing away from the housing.

6. The power conversion device according to any one of claims 1 to 4, characterized by The housing also includes a plurality of protrusions, which are spaced apart on the outer peripheral surface of the housing, and each protrusion is provided with a limiting hole; The power conversion device further includes a plurality of buckles corresponding one-to-one with the plurality of protrusions. The plurality of buckles are disposed on the outer surface of the housing facing the housing. The buckles have hooks, and at least a portion of the hooks pass through the limiting holes and engage with the protrusions.

7. The power conversion device of any one of claims 1-6, wherein, The power conversion device further includes a metal connection bar housed inside the housing. The metal connection bar is located on the side of the circuit board facing the housing and is connected to the circuit board and the electrode connector.

8. The power conversion device of claim 7, wherein, The electrode connector inside the housing is provided with a threaded hole; the power conversion device also includes a fastener, which is housed inside the housing, and the fastener passes through the metal connecting bar and is threadedly connected to the threaded hole.

9. The power conversion device of any of claims 1-8, wherein, The positive electrode pin and the negative electrode pin are staggered on the outer edge of the electrolytic paper, and the positive electrode pin and the negative electrode pin are located on the same side of the electrolytic paper.

10. The power conversion device of any one of claims 1-9, wherein, The outer casing is provided with a mounting through hole and a groove, wherein the mounting through hole is used to pass through the electrode connector, and the groove is provided on the outer periphery of the mounting through hole; The power conversion device further includes a sealing element disposed in the groove, the sealing element abutting between the housing and the outer shell.

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