Photovoltaic inverter

Abstract

Provided in the present application is a photovoltaic inverter. The photovoltaic inverter comprises a housing, and a circuit board and a power conversion circuit that are located in the housing. The housing comprises a first accommodating cavity, a second accommodating cavity, a third accommodating cavity and a fourth accommodating cavity; and the power conversion circuit comprises a first inductor, a bus capacitor and a second inductor which are sequentially connected in series, wherein the bus capacitor is located in the third accommodating cavity; and the first inductor and the second inductor are located in the fourth accommodating cavity. A terminal panel of the housing is provided with a direct-current input terminal and an alternating-current output terminal, wherein the direct-current input terminal extends into the first accommodating cavity and is electrically connected to the first inductor, and the alternating-current output terminal extends into the second accommodating cavity and is electrically connected to the second inductor. During the operation of the photovoltaic inverter, a current sequentially passes through the direct-current input terminal, the first inductor, the bus capacitor, the second inductor and the alternating-current output terminal, such that the current forms an approximate C-shaped flow path in the housing, thereby reducing electromagnetic interference between modules, and improving the electromagnetic compatibility and operating efficiency of the inverted-structure photovoltaic inverter.

Description

A photovoltaic inverter

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411441575.7, filed on October 15, 2024, entitled "A Photovoltaic Inverter", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of electronic technology, and in particular to a photovoltaic inverter. Background Technology

[0004] Power converters can convert one type of current into another and are widely used in power supply and generation systems. A power converter includes a housing, a circuit board inside the housing, a switching assembly mounted on the circuit board, and multiple power devices.

[0005] Power converters must meet electromagnetic compatibility (EMC) standards to be commercially viable. However, as the switching frequency and output power of power converters increase, their electromagnetic immunity (EMS) to other electronic devices decreases, and the electromagnetic signals generated by the power converter itself cause significant electromagnetic interference to its internal components—that is, increased electromagnetic interference (EMI). Therefore, with the increasing power and stricter EMC requirements of power converters, improving the EMC and increasing their operating efficiency has become a key research issue. Summary of the Invention

[0006] This application provides a photovoltaic inverter to improve the electromagnetic compatibility of photovoltaic inverters with inverted circuit structure.

[0007] In a first aspect, this application provides a photovoltaic inverter. The photovoltaic inverter includes a housing, a circuit board, and a power conversion circuit, with the circuit board and power conversion circuit housed within the housing. Specifically, the housing includes a bottom shell and a cover, with the cover covering the bottom shell. A plurality of heat dissipation fins are provided on the surface of the bottom shell facing away from the cover. The circuit board is disposed between the bottom shell and the cover, and the plane of the circuit board is parallel to the surface of the cover relative to the bottom shell. The bottom shell has a plurality of partition plates extending from the bottom shell toward the circuit board, dividing the space between the bottom shell and the circuit board into a plurality of receiving cavities. The plurality of receiving cavities includes a first receiving cavity, a second receiving cavity, a third receiving cavity, and a fourth receiving cavity. The bottom shell or cover includes a terminal panel, which includes DC input terminals and AC output terminals. The first, second, and third receiving cavities are all disposed adjacent to the terminal panel. The third receiving cavity is located between the first and second receiving cavities, and the fourth receiving cavity is located on the side of the third receiving cavity away from the terminal panel. The third receiving cavity is located between the fourth receiving cavity and the first receiving cavity, or between the fourth receiving cavity and the second receiving cavity. The power conversion circuit includes a first inductor, a bus capacitor, and a second inductor connected in series. The bus capacitor is located in a third receiving cavity. The first and second inductors are located in a fourth receiving cavity. A DC input terminal extends through the terminal panel, with one end of the DC input terminal extending into the first receiving cavity electrically connected to the first inductor, and the other end of the DC input terminal used for electrical connection to the photovoltaic module. An AC output terminal extends through the terminal panel, with one end of the AC output terminal extending into the second receiving cavity electrically connected to the second inductor, and the other end of the AC output terminal used for electrical connection to the power grid or load. The power conversion circuit also includes a power module located in the third receiving cavity, with an insulating and thermally conductive substrate between the power module and the bottom wall of the third receiving cavity.

[0008] In the embodiments of this application, the photovoltaic inverter adopts an inverted structure to simplify the cable design of the power conversion circuit. Compared to the forward-facing arrangement of the power conversion circuit within the housing (where the first inductor, bus capacitor, and second inductor are located between the circuit board and the cover), the inverted structure allows for a shorter distance between the heat-generating components and the bottom shell. This means a shorter heat transfer distance is required, allowing the heat sink fins to directly transfer the heat generated by the heat-generating components from the bottom shell to the fins for dissipation, thus accelerating heat dissipation within the photovoltaic inverter. When the photovoltaic inverter is operating, the current enters from the DC input terminal, passes sequentially through the first inductor, bus capacitor, and second inductor, and exits from the AC output terminal. The current flows sequentially along the first, third, and fourth housings, forming an approximately C-shaped current path within the housing. This reduces current path intersections, thereby decreasing the impedance of the power conversion circuit. Meanwhile, by placing the aforementioned multiple devices in separate housing cavities, electromagnetic interference between the devices can be reduced, thereby improving the electromagnetic compatibility of the photovoltaic inverter, which in turn reduces the losses of the photovoltaic inverter and improves its operating efficiency.

[0009] Because the bus capacitor is relatively large, to improve the space utilization of the housing, in one possible implementation, a groove is provided on the surface of the bottom shell facing the cover within the third receiving cavity, and the bus capacitor is partially accommodated in the groove. In this way, the surface shape of the bottom shell facing the cover is the same as the surface shape of the power conversion circuit facing the bottom shell, thereby making the heat conduction path between the bottom shell and the modules of the photovoltaic inverter more uniform, and resulting in a smaller volume compared to photovoltaic inverters with a flat bottom shell.

[0010] The aforementioned groove may be equipped with an insulating membrane, and an explosion-proof valve is installed on the side of the bus capacitor facing the insulating membrane. The explosion-proof valve is spaced a predetermined distance from the insulating membrane. When the explosion-proof valve is opened, the valve cover of the explosion-proof valve pops out and abuts against the insulating membrane. The insulating membrane can keep the bottom shell and the bus capacitor insulated, preventing the bus capacitor from short-circuiting with other devices through the bottom shell in the event of a fault.

[0011] Additionally, when the bus capacitor fails, the electrolyte inside the bus capacitor may be ejected. In one possible implementation, the aforementioned plurality of partitions includes a first partition, with a first receiving cavity and a third receiving cavity separated by the first partition. Within the third receiving cavity, a guide plate is provided on the side of the bottom shell facing the cover, the plane of which is perpendicular to the surface of the cover relative to the bottom shell. The guide plate is located between the groove and the terminal panel, with one end connected to the first partition and the other end inclined towards the terminal panel, thereby diverting the electrolyte within the groove to prevent it from flowing into other receiving cavities and damaging other components.

[0012] In one possible implementation, the power conversion circuit further includes a first communication circuit, which is housed within a third receiving cavity and positioned near the terminal panel. The terminal panel also includes a first communication terminal extending through the terminal panel, with one end of the first communication terminal extending into the third receiving cavity electrically connected to the first communication circuit. The first communication terminal is used for parallel data transmission to an external device. The other end of the guide plate is inclined towards the first communication terminal. In this technical solution, since the first communication circuit is a low-voltage circuit, the guide plate directs the electrolyte in the groove towards the first communication terminal, preventing the electrolyte from entering the high-voltage circuit and causing damage to the power conversion circuit.

[0013] In one possible implementation, the aforementioned plurality of partitions may further include a second partition. The second partition divides the fourth receiving cavity into a first cavity and a second cavity. The first cavity and the second cavity are respectively disposed adjacent to the third receiving cavity. The first inductor is housed in the first cavity, and the second inductor is housed in the second cavity. Within the fourth receiving cavity, the second partition separates the first inductor and the second inductor, which can reduce interference between the first inductor and the second inductor. Furthermore, the second partition can increase the heat dissipation area between the first inductor and the housing, as well as the heat dissipation area between the second inductor and the housing, thereby improving the heat dissipation efficiency for both the first and second inductors.

[0014] In one possible implementation, the power module includes a first switching transistor and a second switching transistor. The first switching transistor is electrically connected between a DC input terminal and a first inductor, and the second switching transistor is electrically connected between a bus capacitor and a second inductor. The first switching transistor is positioned close to the first inductor, and the second switching transistor is positioned close to the second inductor. The first switching transistor can be used to connect or disconnect the electrical connection between the first inductor and the DC input terminal, and the second switching transistor can be used to connect or disconnect the electrical connection between the second inductor and the bus capacitor. By separating the switching transistors from the inductors, interference between the switching transistors and the inductors can be reduced, and the heat dissipation area between the power module and the chassis can be increased.

[0015] In one possible implementation, the power conversion circuit further includes multiple relays located between the circuit board and the base housing. The multiple partitions include a third partition, which isolates the second and third receiving cavities. A thermal pad is provided at the end of the third partition facing the cover, and this thermal pad is used to contact the circuit board. The multiple relays are arranged in two rows on either side of the thermal pad. When the photovoltaic inverter is operating, the relays and areas of the circuit board near the relays generate heat. The thermal pad can adhere to the circuit board, thereby transferring heat from the area near the relays on the circuit board to the base housing, further reducing the heat generated by the relays.

[0016] In one possible implementation, the third partition plate is further provided with a metal bracket at the end facing the cover. The thermal pad is fixed to the end of the metal bracket facing the cover, and the aforementioned multiple relays are distributed in two rows on both sides of the metal bracket. Therefore, the metal bracket can both accommodate the relays and transfer the heat of the thermal pad to the bottom shell.

[0017] In one possible implementation, the plurality of receiving cavities further includes a fifth receiving cavity, which is disposed adjacent to the terminal panel and located between the third and second receiving cavities. The power conversion circuit also includes a second communication circuit. The second communication circuit is housed within the fifth receiving cavity and is used to send and receive interactive data. The terminal panel also includes a second communication terminal. The second communication terminal extends through the terminal panel, and one end of the second communication terminal extending into the fifth receiving cavity is electrically connected to the second communication circuit. The second communication terminal is used to serially transmit data to external devices. In this technical solution, the second communication terminal is disposed on the same side as the DC input terminal and the AC output terminal, which allows the wiring of the photovoltaic inverter to be arranged on the same side, facilitating the installation of the photovoltaic inverter.

[0018] In one possible implementation, the photovoltaic inverter also includes a switch housed in the housing and connected between the DC input terminal and the first inductor. This switch is used to connect or disconnect the electrical connection between the photovoltaic module and the power conversion circuit, thereby disconnecting the output DC power of the photovoltaic module from the DC input circuit of the photovoltaic inverter in the event of a fault, thus protecting the photovoltaic inverter.

[0019] In one possible implementation, the side of the circuit board facing the cover also includes surface-mount resistors, surface-mount capacitors, and indicator lights. The indicator lights are used to indicate the operating status of the photovoltaic inverter. In the inverted structure, the space between the circuit board and the cover is smaller, allowing for the installation of smaller components and making full use of the space within the housing. Attached Figure Description

[0020] Figure 1 is a schematic diagram of an application scenario of the photovoltaic system provided in an embodiment of this application;

[0021] Figure 2 is a front view of the photovoltaic inverter provided in the embodiment of this application;

[0022] Figure 3 is a schematic diagram of the back of the photovoltaic inverter provided in the embodiment of this application;

[0023] Figure 4 is an exploded view of the photovoltaic inverter provided in the embodiment of this application;

[0024] Figure 5 is a schematic diagram of the bottom shell provided in an embodiment of this application;

[0025] Figure 6 is a schematic diagram of the power conversion circuit and the bottom shell provided in an embodiment of this application;

[0026] Figure 7 is a schematic diagram of the current path of the photovoltaic inverter provided in the embodiment of this application during operation;

[0027] Figure 8 is a schematic diagram of a power conversion circuit provided in an embodiment of this application;

[0028] Figure 9 is another schematic diagram of the bottom shell provided in an embodiment of this application;

[0029] Figure 10 is another schematic diagram of the power conversion circuit and the bottom shell provided in an embodiment of this application;

[0030] Figure 11 is another schematic diagram of the bottom shell provided in an embodiment of this application;

[0031] Figure 12 is a schematic cross-sectional view of the bottom shell along the AA direction in Figure 11;

[0032] Figure 13 is a cross-sectional schematic diagram of the photovoltaic inverter provided in the embodiment of this application along the AA direction in Figure 11;

[0033] Figure 14 is another schematic diagram of the bottom shell provided in an embodiment of this application;

[0034] Figure 15 is a cross-sectional view of the bottom shell along the BB direction in Figure 14;

[0035] Figure 16 is a schematic diagram of the power conversion circuit and the bottom shell provided in an embodiment of this application;

[0036] Figure 17 is another schematic diagram of the bottom shell provided in an embodiment of this application;

[0037] Figure 18 is another schematic diagram of the power conversion circuit provided in an embodiment of this application;

[0038] Figure 19 is another schematic diagram of the bottom shell provided in an embodiment of this application;

[0039] Figure 20 is a schematic diagram of the thermal pad and metal bracket provided in an embodiment of this application;

[0040] Figure 21 is another schematic diagram of the bottom shell provided in an embodiment of this application.

[0041] Figure reference numerals: 10-Photovoltaic system; 11-Photovoltaic module; 12-Photovoltaic inverter; 13-Energy storage device; 20-Grid; 31-First housing cavity; 32-Second housing cavity; 33-Third housing cavity; 34-Fourth housing cavity; 35-Fifth housing cavity; 121-Housing shell; 122-Power conversion circuit; 123-Switch; 331-Groove; 332-Guide plate; 333-Insulating film; 334-Thermal pad; 335-Metal bracket; 336-First insulating thermal conductive substrate; 337-Second insulating thermal conductive substrate; 341-Second partition plate; 342-First cavity; 343-Second cavity; 1210-Terminal panel; 1211-Cover; 1212-Bottom shell; 1213-DC input terminal; 1214-AC output terminal; 121 5-Separator Plate 1216-Heat Dissipation Fins 1217-First Communication Terminal 1218-Second Communication Terminal 1221-DC Input Circuit 1222-DC Converter Circuit 1223-Bus Capacitor 1224-Inverter Circuit 1225-AC Output Circuit 1226-Circuit Board 1227-Filter Circuit 1228-First Communication Circuit 1229-Second Communication Circuit 12151-First Separator Plate 12152-Third Separator Plate 12221-First Inductor 12222-First Switching Transistor 12241-Second Inductor 12242-Second Switching Transistor 12271-Relay 12261-Surface Mount Resistor 12262-Surface Mount Capacitor 12263-Signal Indicator Light Detailed Implementation

[0042] 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.

[0043] To facilitate understanding of the photovoltaic inverter provided in this application embodiment, its application scenarios are described below. The photovoltaic inverter of this application can be applied to power supply systems and power generation systems. Taking a photovoltaic system as an example, the photovoltaic system can be used in two application scenarios: residential power stations and industrial photovoltaic power stations. The photovoltaic inverter can convert solar energy into electrical energy to supply the grid or load. Figure 1 is a schematic diagram of an application scenario of the photovoltaic system provided in this application embodiment. As shown in Figure 1, the photovoltaic system 10 is applied in a residential power station. Specifically, the photovoltaic module 11 is used to convert light energy into electrical energy. The photovoltaic system 10 includes a photovoltaic inverter 12, one end of which is used to connect to the photovoltaic module 11, and the other end is used to connect to the power grid 20. The photovoltaic inverter 12 is used to convert the direct current from the photovoltaic module 11 into alternating current and transmit the alternating current to the power grid 20. A photovoltaic optimizer can also be installed in the photovoltaic system 10, which can be used to improve the power generation efficiency of the photovoltaic module 11. The photovoltaic optimizer is a DC-input, DC-output module-level power electronic device. Connected in series with the photovoltaic module 11, it employs predictive current and voltage technology to ensure the module is always in optimal operating condition. Following the working principle of a step-down topology, it addresses the impact of shading, inconsistent orientation, or differences in module electrical specifications on power generation in photovoltaic power plants, achieving maximum power output from the photovoltaic module 11 and thus increasing the power generation of the photovoltaic system 10. The photovoltaic system 10 may also include an energy storage device 13. The AC power converted by the photovoltaic inverter 12 can also be transmitted to the energy storage device 13 for energy storage. Furthermore, a grid-connected / off-grid controller can be installed between the photovoltaic inverter 12 and the grid 20. The photovoltaic inverter 12 converts the DC power provided by the photovoltaic module 11 into AC power and transmits the AC power to the grid-connected / off-grid controller. The grid-connected / off-grid controller can also be electrically connected to electrical appliances. In practical applications, the grid-connected / off-grid controller has both off-grid and grid-connected states. When the grid-connected controller is in off-grid mode, it is not electrically connected to the grid 20, and the AC power transmitted by the photovoltaic inverter 12 is only supplied to electrical appliances. These electrical appliances include household appliances such as televisions, air conditioners, refrigerators, and washing machines. When the grid-connected controller is in grid-connected mode, it is electrically connected to the grid 20 via a power sensor. When the electrical energy generated by the photovoltaic module 11 cannot meet the power demand of the electrical appliances, the grid 20 can supply power to the photovoltaic system 10 through the grid-connected controller. When the power generation of the photovoltaic module 11 exceeds the power consumption of the electrical appliances, the grid-connected controller can transmit the excess power to the grid 20. The power sensor is used to measure the power flow between the photovoltaic system 10 and the grid 20; for example, the power sensor can be an electricity meter.

[0044] As the requirements for loss and efficiency in photovoltaic systems increase, the electromagnetic compatibility (EMC) requirements for photovoltaic inverters are also gradually becoming more stringent. Therefore, improving the EMC of photovoltaic inverters has become an important research issue.

[0045] In view of this, this application provides a photovoltaic inverter to improve the electromagnetic compatibility of photovoltaic inverters with inverted circuit structure.

[0046] It should be noted that the terminology used in the following embodiments is for the purpose of describing specific embodiments only and is not intended to be a limitation of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise.

[0047] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0048] In this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0049] Furthermore, in this article, directional terms such as "top," "bottom," "upper," and "lower" are defined relative to the orientation of the structure as shown in the attached drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation of the structure.

[0050] Figure 2 is a front view of the photovoltaic inverter provided in the embodiment of this application, Figure 3 is a rear view of the photovoltaic inverter provided in the embodiment of this application, and Figure 4 is an exploded view of the photovoltaic inverter provided in the embodiment of this application. As shown in Figures 2 to 4, the photovoltaic inverter 12 includes a housing 121 and a power conversion circuit 122. The housing 121 includes a cover 1211 and a bottom shell 1212. The cover 1211 is used to cover the bottom shell 1212 and form an internal space for accommodating the power conversion circuit 122. In practical applications, the side surface of the bottom shell 1212 facing away from the cover 1211 (i.e., the back side) is mounted on a mounting plate, and the cover 1211 (i.e., the front side) faces the user.

[0051] It should be noted that in some embodiments, the bottom shell 1212 can be a basin-shaped structure, that is, the bottom shell 1212 includes a bottom shell base plate and a plurality of bottom shell side plates, which are connected in sequence and arranged perpendicularly to the bottom shell base plate. In this embodiment, the cover 1211 can be a plate-shaped structure and is arranged opposite to the bottom shell base plate. The outer periphery of the cover 1211 is connected to the aforementioned plurality of bottom shell side plates, thereby forming a space for accommodating the power conversion circuit 122. Of course, in this embodiment, the cover 1211 can also be a basin-shaped structure, that is, the cover 1211 includes a cover base plate and a plurality of cover side plates, which are connected in sequence and arranged perpendicularly to the cover base plate. The cover base plate is arranged opposite to the bottom shell base plate, and the aforementioned plurality of cover side plates are connected to the aforementioned plurality of bottom shell side plates, thereby forming a space for accommodating the power conversion circuit 122. In other embodiments, the cover 1211 can be a basin-shaped structure. The bottom shell 1212 can be a plate-shaped structure and is arranged opposite to the cover base plate. The bottom shell 1212 is connected to the aforementioned multiple cover side plates, thereby forming a space that can accommodate the power conversion circuit 122.

[0052] The structure of the photovoltaic inverter 12 will be described in detail below, taking the shell 121, which can be a basin-shaped structure for the bottom shell 1212 and a plate-shaped structure for the cover 1211 as an example.

[0053] The photovoltaic inverter of this application adopts an inverted-button structure to simplify the cable design of the power conversion circuit and achieve centralized heat dissipation for heat-generating components. As shown in Figure 4, the photovoltaic inverter 12 also includes a circuit board 1226. The plane of the circuit board 1226 is parallel to the surface of the cover 1211 relative to the bottom shell 1212. Specifically, the front of the circuit board 1226 faces the cover 1211, and the switching components and multiple power devices of the power conversion circuit 122 are located on the back of the circuit board 1226 and facing the bottom plate of the bottom shell 1212. In this way, the switching components and multiple power devices can be rigidly connected to the circuit board 1226 through pins, thereby simplifying the cable design.

[0054] As shown in Figure 3, in the housing 121 of this application, the bottom shell 1212 has multiple heat dissipation fins 1216 on the side surface facing away from the cover 1211. Compared to the power conversion circuit 122 being arranged in the housing 121 (i.e., the first inductor 12221, bus capacitor 1223, and second inductor 12241 are located on the side of the circuit board 1226 facing the cover 1211), in the above embodiment, the inverted structure allows for a shorter distance between the heat-generating device and the bottom shell 1212, meaning a shorter heat transfer distance is required. The heat dissipation fins 1216 can directly transfer the heat generated by the heat-generating device from the bottom shell 1212 to the heat dissipation fins 1216, and dissipate the heat through the heat dissipation fins 1216, thereby accelerating the heat dissipation inside the photovoltaic inverter 12.

[0055] Figure 5 is a schematic diagram of the bottom shell provided in an embodiment of this application. As shown in Figure 5, the bottom shell 1212 is provided with a plurality of partition plates 1215. The partition plates 1215 extend from the bottom shell 1212 toward the circuit board 1226 and divide the space between the bottom shell 1212 and the circuit board 1226 into a plurality of receiving cavities, which are separated from each other. The plurality of receiving cavities include a first receiving cavity 31, a second receiving cavity 32, a third receiving cavity 33, and a fourth receiving cavity 34. The housing 121 includes a terminal panel 1210, which may be part of the bottom shell 1212 or part of the cover 1211. As shown in Figures 2 and 3, the terminal panel 1210 is a bottom shell side plate of the bottom shell 1212. The terminal panel 1210 includes a DC input terminal 1213 and an AC output terminal 1214. In this embodiment, the first receiving cavity 31, the second receiving cavity 32, and the third receiving cavity 33 are all disposed adjacent to the terminal panel 1210. That is, the terminal panel 1210 may form sidewalls for a first receiving cavity 31, a second receiving cavity 32, and a third receiving cavity 33. The third receiving cavity 33 is located between the first receiving cavity 31 and the second receiving cavity 32, and the fourth receiving cavity 34 is located on the side of the third receiving cavity 33 away from the terminal panel 1210. The third receiving cavity 33 is located between the fourth receiving cavity 34 and the first receiving cavity 31, or the third receiving cavity 33 is located between the fourth receiving cavity 34 and the second receiving cavity 32.

[0056] Figure 6 is a schematic diagram of the power conversion circuit and the base provided in an embodiment of this application, and Figure 7 is a schematic diagram of the current path of the photovoltaic inverter provided in an embodiment of this application during operation. As shown in Figures 6 and 7, in the embodiment of this application, the power conversion circuit 122 includes a first inductor 12221, a bus capacitor 1223, and a second inductor 12241 connected in series. The bus capacitor 1223 is located in the third receiving cavity 33. The first inductor 12221 and the second inductor 12241 are located in the fourth receiving cavity 34. The DC input terminal 1213 passes through the terminal panel 1210, and one end of the DC input terminal 1213 extending into the first receiving cavity 31 is electrically connected to the first inductor 12221, while the other end of the DC input terminal 1213 is electrically connected to the photovoltaic module 11. The AC output terminal 1214 passes through the terminal panel 1210, and one end of the AC output terminal 1214 extending into the second receiving cavity 32 is electrically connected to the second inductor 12241, while the other end of the AC output terminal 1214 is electrically connected to the power grid 20 or the load.

[0057] When the photovoltaic inverter 12 is operating, current flows sequentially through the DC input terminal 1213, the first inductor 12221, the bus capacitor 1223, the second inductor 12241, and the AC output terminal 1214. This causes the current to flow sequentially along the first receiving cavity 31, the third receiving cavity 33, the fourth receiving cavity 34, the third receiving cavity 33, the fourth receiving cavity 34, the third receiving cavity 33, and the second receiving cavity 32, forming an approximately C-shaped current path within the housing 121. This reduces current path intersections, thereby reducing the impedance of the power conversion circuit 122. Simultaneously, by placing these multiple components in separate receiving cavities, electromagnetic interference between components is reduced, improving the electromagnetic compatibility of the photovoltaic inverter 12. This, in turn, reduces the losses of the photovoltaic inverter 12 and increases its operating efficiency, ultimately achieving reduced losses and increased efficiency in the photovoltaic system 10.

[0058] Figure 8 is a schematic diagram of a power conversion circuit provided in an embodiment of this application. As shown in Figure 8, in the photovoltaic inverter 12, the power conversion circuit 122 includes a DC-DC converter 1222, a bus capacitor 1223, and an inverter circuit 1224. The DC-DC converter 1222 includes a first inductor 12221, and the inverter circuit 1224 includes a second inductor 12241. Further, the power conversion circuit 122 also includes a filter circuit 1227 and a relay 12271. The filter circuit 1227 is connected between the inverter circuit 1224 and the AC output terminal 1214, and the relay 12271 is connected between the filter circuit 1227 and the AC output terminal 1214. The relay 12271 can be used as an output protection switch to ensure the stability of the output current. Additionally, the power conversion circuit 122 may also include a DC input circuit 1221 and an AC output circuit 1225. A DC input circuit 1221 is connected between a DC input terminal 1213 and a DC-DC converter circuit 1222. The DC input circuit 1221 is housed within a first receiving cavity 31 and is connected to the DC input terminal 1213. An AC output circuit 1225 is connected between a relay 12271 and an AC output terminal 1214 and is housed within a second receiving cavity 32.

[0059] In addition, the power conversion circuit 122 also includes a power module located within the third receiving cavity 33. An insulating thermally conductive substrate is disposed between the power module and the bottom wall of the third receiving cavity 33. The insulating thermally conductive substrate thermally connects the power module to the bottom shell 1212, accelerating the heat dissipation efficiency of the power module. Furthermore, in the event of a fault in the bus capacitor 1223, the insulating thermally conductive substrate can prevent a short circuit between the bottom shell 1212 and the power module when the bus capacitor 1223 is short-circuited to the bottom shell 1212.

[0060] Figure 9 is another schematic diagram of the bottom shell provided in an embodiment of this application. As shown in Figure 9, the photovoltaic inverter 12 also includes a switch 123, which is connected to the DC input circuit 1221 and is used to connect or disconnect the DC input circuit 1221. In this way, when the photovoltaic system 10 fails, the switch 123 can disconnect the electrical connection between the photovoltaic module 11 and the DC input circuit 1221, thereby disconnecting the DC output power of the DC input circuit 1221 from the photovoltaic module 11, so as to protect the photovoltaic inverter 12.

[0061] In the inverted structure described above, the space between the circuit board 1226 and the cover 1211 is relatively small, allowing for the placement of smaller components to fully utilize the space within the housing 121. Figure 10 is another schematic diagram of the power conversion circuit and bottom shell provided in an embodiment of this application. As shown in Figure 10, in one embodiment, the side of the circuit board 1226 facing the cover 1211 is also provided with a surface mount resistor 12261, a surface mount capacitor 12262, and a signal indicator 12263. The surface mount resistor 12261 can be used to limit current in the circuit, suppress interference and noise, etc., while the surface mount capacitor 12262 can be used to store charge. The signal indicator 12263 is used to indicate the operating status of the photovoltaic inverter 12, such as normal operation, standby, communication connection, etc. In this embodiment, the number of signal indicator 12263 is not limited. For example, in one embodiment, one signal indicator 12263 can be provided, and different colors can be displayed by the signal indicator 12263 to indicate the status of the photovoltaic inverter 12. Alternatively, in another embodiment, multiple indicator lights 12263 can be provided, each displaying a different color, and all multiple indicator lights 12263 have different colors. In this way, each indicator light 12263 can consistently represent a state of the photovoltaic inverter 12.

[0062] Figure 11 is another schematic diagram of the bottom shell provided in an embodiment of this application, Figure 12 is a cross-sectional schematic diagram of the bottom shell in Figure 1 along the AA direction, and Figure 13 is a cross-sectional schematic diagram of the photovoltaic inverter provided in an embodiment of this application along the AA direction in Figure 11. As shown in Figures 11, 12, and 13, due to the large volume of the bus capacitor 1223, in order to improve the space utilization rate within the housing 121, in one embodiment, a groove 331 is provided on the surface of the bottom shell 1212 facing the cover 1211 in the third receiving cavity 33, and the bus capacitor 1223 is partially accommodated in the groove 331. In this way, the surface shape of the bottom shell 1212 facing the cover 1211 is the same as the surface shape of the power conversion circuit 122 facing the bottom shell 1212. That is, the surface shape of the bottom shell 1212 facing the cover 1211 can be designed to match the position of the circuit devices on the circuit board 1226, thereby making the gap between the bottom shell 1212 and each module of the power conversion circuit 122 more uniform, and smaller in volume compared to a photovoltaic inverter with a flat bottom shell. In addition, this structural design can reduce the size of the photovoltaic inverter 12 and increase the heat dissipation area of ​​the circuit devices.

[0063] Additionally, when the bus capacitor 1223 malfunctions, the electrolyte inside the bus capacitor 1223 may be ejected from the bus capacitor 1223. Figure 14 is another schematic diagram of the bottom shell provided in an embodiment of this application, and Figure 15 is a cross-sectional view of the bottom shell in Figure 14 along the BB direction. As shown in Figures 14 and 15, in one embodiment, the aforementioned plurality of partition plates 1215 include a first partition plate 12151, and the first receiving cavity 31 and the third receiving cavity 33 are separated by the first partition plate 12151, that is, the first receiving cavity 31 and the third receiving cavity 33 are located on both sides of the first partition plate 12151. In the third receiving cavity 33, a guide plate 332 may be provided on the side surface of the bottom shell 1212 facing the cover 1211, and the plane of the guide plate 332 is perpendicular to the surface of the cover 1211 relative to the bottom shell 1212. The guide plate 332 is located between the groove 331 and the terminal panel 1210. One end of the guide plate 332 is connected to the first partition plate 12151, and the other end extends toward the second side of the housing 122. In practical applications, the first partition plate 12151 and the circuit board 1226 cannot be completely fitted together. Therefore, without the guide plate 332, the electrolyte in the groove 331 flows to the first partition plate 12151 under the action of gravity, and flows into the first receiving cavity 31 through the gap between the first partition plate 12151 and the circuit board 1226. Since the DC input circuit 1221 in the first receiving cavity 31 is a high-voltage device, the electrolyte flowing into the first receiving cavity 31 will cause a short circuit in the high-voltage circuit, posing a significant safety risk. As shown in Figure 14, the guide plate 332 guides the electrolyte in the groove 331 to the side of the third receiving cavity 33 closer to the second side, which can prevent the electrolyte from entering the first receiving cavity 31 and damaging the electronic components of the DC input circuit 1221.

[0064] As shown in Figure 13, the groove 331 may be provided with an insulating film 333. An explosion-proof valve is provided on the side of the bus capacitor 1223 facing the insulating film 333. The explosion-proof valve is spaced a predetermined distance from the insulating film 333. When the explosion-proof valve is opened, the valve cover of the explosion-proof valve pops out and abuts against the insulating film 333. The insulating film 333 can maintain insulation between the bottom shell 1212 and the bus capacitor 1223, preventing the bus capacitor 1223 from short-circuiting with other devices through the bottom shell 1212 in the event of a fault.

[0065] Figure 16 is a schematic diagram of the power conversion circuit and the base shell provided in an embodiment of this application. As shown in Figures 2 and 16, in one embodiment, the terminal panel 1210 further includes a first communication terminal 1217. The power conversion circuit 122 further includes a first communication circuit 1228, which is housed within a third receiving cavity 33. The first communication terminal 1217 penetrates the terminal panel 1210, and one end of the first communication terminal 1217 extending into the third receiving cavity 33 is electrically connected to the first communication circuit 1228. In this embodiment, the first communication terminal 1217 is used to transmit data in parallel to external devices and can send and receive parameter data of the photovoltaic inverter 12. For example, the first communication terminal 1217 can communicate with external devices via wireless connection methods such as 4G or FE (fast ethernet). In this embodiment, the other end of the guide plate 332 is inclined toward the first communication terminal 1217. Since the first communication circuit 1228 is a low-voltage circuit, the guide plate 332 directs the electrolyte in the groove 331 toward the first communication terminal 1217, which can prevent the electrolyte from entering the high-voltage circuit and causing damage to the power conversion circuit 122.

[0066] Figure 17 is a schematic diagram of the power conversion circuit and the base provided in an embodiment of this application, and Figure 18 is another schematic diagram of the base provided in an embodiment of this application. As shown in Figures 17 and 18, in one embodiment, the power module includes a first switching transistor 12222 and a second switching transistor 12242. The first switching transistor 12222 is electrically connected between the DC input terminal 1213 and the first inductor 12221, and the second switching transistor 12242 is electrically connected between the bus capacitor 1223 and the second inductor 12241. The first switching transistor 12222 and the second switching transistor 12242 are located in the third receiving cavity 33, with the first switching transistor 12222 disposed close to the first inductor 12221 and the second switching transistor 12242 disposed close to the second inductor 12241. By separating the switching transistors from the inductors, interference between the switching transistors and the inductors can be reduced, and the heat dissipation area of ​​the DC conversion circuit 1222 and the inverter circuit 1224 can be increased respectively.

[0067] In the aforementioned photovoltaic inverter 12, the third receiving cavity 33 is provided with a first insulating thermally conductive substrate 336 and a second insulating thermally conductive substrate 337. The surface of the first switching transistor 12222 facing the bottom shell 1212 is attached to the first insulating thermally conductive substrate 336, and the surface of the second switching transistor 12242 facing the bottom shell 1212 is attached to the second insulating thermally conductive substrate 337. The first insulating thermally conductive substrate 336 thermally connects the first switching transistor 12222 to the bottom shell 1212, and the second insulating thermally conductive substrate 337 thermally connects the second switching transistor 12242 to the bottom shell 1212, thereby accelerating the heat dissipation efficiency of the first switching transistor 12222 and the second switching transistor 12242. Furthermore, the first switch transistor 12222, the second switch transistor 12242, and the bus capacitor 1223 are located in the same housing cavity. The first insulating heat-conducting substrate 336 and the second insulating heat-conducting substrate 337 can reduce the impact of the bus capacitor 1223 on the first switch transistor 12222 and the second switch transistor 12242 when the bus capacitor 1223 fails.

[0068] As shown in Figure 4, in one embodiment, a second partition plate 341 is provided within the fourth receiving cavity 34, dividing the fourth receiving cavity 34 into a first cavity 342 and a second cavity 343. The first cavity 342 and the second cavity 343 are respectively arranged adjacent to the third receiving cavity 33. A first inductor 12221 is housed within the first cavity 342, and a second inductor 12241 is housed within the second cavity 343. Within the fourth receiving cavity 34, the second partition plate 341 separates the first inductor 12221 and the second inductor 12241, which can reduce interference between the first inductor and the second inductor 12241. Furthermore, the second partition plate 341 increases the heat dissipation area between the first inductor 12221 and the housing 121, as well as the heat dissipation area between the second inductor 12241 and the housing 121, thereby improving the heat dissipation efficiency of the first inductor 12241 and the second inductor 12241.

[0069] In one embodiment, the power conversion circuit 122 further includes a plurality of relays. These relays are located on the side of the circuit board 1226 opposite to the cover 1211. Figure 19 is another schematic diagram of the power conversion circuit provided in an embodiment of this application. As shown in Figure 19, the plurality of partitions 1215 further includes a third partition 12152, which separates the third receiving cavity 33 from the second receiving cavity 32, i.e., the third receiving cavity 33 and the second receiving cavity 32 are located on opposite sides of the third partition 12152. A thermal pad 334 is provided on the side of the third partition 12152 facing the cover 1211, and the thermal pad 334 is used to contact the circuit board 1226. The plurality of relays are arranged in two rows on both sides of the thermal pad 334. When the photovoltaic inverter 12 is operating, the relays and the area of ​​the circuit board 1226 near the relays will generate heat. The thermal pad 334 can be used to attach the circuit board 1226 of the power conversion circuit 122, so that the heat near the relay on the circuit board 1226 can be transferred from the thermal pad 334 to the bottom shell 1212, thereby reducing the heat of the relay and preventing the relay from overheating and malfunctioning.

[0070] In this application, the relay has pins on the side facing the circuit board 1226. These pins are fixed to the circuit board 1226 and connected to metal traces. The multiple relays are distributed around the outer periphery of the thermal pad 334, which reduces the distance between the area of ​​the circuit board 1226 near the relays and the thermal pad 334. Figure 20 is a schematic diagram of the thermal pad and metal bracket provided in an embodiment of this application. As shown in Figures 19 and 20, in one embodiment, the third partition plate 12152 also has a metal bracket 335 on the side facing the cover 1211. The thermal pad 334 is fixed to the side of the metal bracket 335 facing the cover 1211. The multiple relays are arranged in two rows on both sides of the metal bracket 335. Therefore, the metal bracket 335 can both accommodate the relays and transfer the heat from the thermal pad 334 to the bottom shell 1212.

[0071] Figure 21 is another schematic diagram of the bottom shell provided in an embodiment of this application. As shown in Figures 2, 3, and 21, in one embodiment, the terminal panel 1210 further includes a second communication terminal 1218. The aforementioned plurality of receiving cavities also include a fifth receiving cavity 35, which is disposed adjacent to the terminal panel 1210 and is located between the second receiving cavity 32 and the third receiving cavity 33. The power conversion circuit 122 further includes a second communication circuit, which is housed within the fifth receiving cavity 35. The second communication terminal 1218 penetrates the terminal panel 1210, and one end of the second communication terminal 1218 extending into the fifth receiving cavity 35 is electrically connected to the second communication circuit. The second communication terminal 1218 is used to serially transmit data to an external device; for example, the second communication terminal 1218 can be connected to an external device via a communication cable. In this embodiment, the second communication terminal 1218 is disposed on the same side as the DC input terminal 1213 and the AC output terminal 1214, which allows the wiring of the photovoltaic inverter 12 to be disposed on the same side, facilitating the installation of the photovoltaic inverter 12.

[0072] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A photovoltaic inverter, characterized in that, The system includes a housing, a circuit board, and a power conversion circuit, wherein the circuit board and the power conversion circuit are housed within the housing, wherein: The housing includes a bottom shell and a cover, the cover being used to cover the bottom shell; the bottom shell has multiple heat dissipation fins on its surface opposite to the cover; the circuit board is disposed between the bottom shell and the cover, and the plane of the circuit board is parallel to the surface of the cover relative to the bottom shell; the bottom shell has multiple partition plates extending from the bottom shell toward the circuit board, dividing the space between the bottom shell and the circuit board into multiple receiving cavities; The plurality of receiving cavities includes a first receiving cavity, a second receiving cavity, a third receiving cavity, and a fourth receiving cavity; the bottom shell or the cover includes a terminal panel, the terminal panel including a DC input terminal and an AC output terminal, the first receiving cavity, the second receiving cavity, and the third receiving cavity are all disposed adjacent to the terminal panel, the third receiving cavity is located between the first receiving cavity and the second receiving cavity, the fourth receiving cavity is located on the side of the third receiving cavity away from the terminal panel, the third receiving cavity is located between the fourth receiving cavity and the first receiving cavity, or the third receiving cavity is located between the fourth receiving cavity and the second receiving cavity; The power conversion circuit includes a first inductor, a bus capacitor, and a second inductor connected in series. The bus capacitor is located in the third receiving cavity, and the first and second inductors are located in the fourth receiving cavity. The DC input terminal extends through the terminal panel, with one end of the DC input terminal extending into the first receiving cavity electrically connected to the first inductor, and the other end of the DC input terminal used for electrical connection to the photovoltaic module. The AC output terminal extends through the terminal panel, with one end of the AC output terminal extending into the second receiving cavity electrically connected to the second inductor, and the other end of the AC output terminal used for electrical connection to the power grid or load. The power conversion circuit further includes a power module located within the third receiving cavity, and an insulating and heat-conducting substrate is provided between the power module and the bottom wall of the third receiving cavity.

2. The photovoltaic inverter as described in claim 1, characterized in that, Within the third accommodating cavity, a groove is provided on the side surface of the bottom shell facing the cover, and the bus capacitor portion is accommodated within the groove.

3. The photovoltaic inverter as described in claim 2, characterized in that, An insulating film is provided in the groove, and an explosion-proof valve is provided on the side surface of the bus capacitor facing the insulating film, with the explosion-proof valve and the insulating film spaced at a set distance apart.

4. The photovoltaic inverter as described in any one of claims 1 to 3, characterized in that, The plurality of partitions includes a first partition, wherein the first receiving cavity and the third receiving cavity are separated by the first partition; Within the third accommodating cavity, a guide plate is provided on the side of the bottom shell facing the cover, and the plane of the guide plate is perpendicular to the surface of the cover relative to the bottom shell; the guide plate is located between the groove and the terminal panel, one end of the guide plate is connected to the first partition plate, and the other end of the guide plate is inclined toward the terminal panel.

5. The photovoltaic inverter as described in claim 4, characterized in that, The power conversion circuit further includes a first communication circuit, which is housed within the third receiving cavity and is disposed close to the terminal panel. The terminal panel also includes a first communication terminal, which extends through the terminal panel and is electrically connected to the first communication circuit at one end of the first communication terminal that extends into the third receiving cavity. The first communication terminal is used to transmit data to an external device in parallel. The other end of the guide plate is inclined toward the first communication terminal.

6. The photovoltaic inverter as described in any one of claims 1 to 5, characterized in that, The plurality of partitions includes a second partition, which divides the fourth receiving cavity into a first cavity and a second cavity. The first cavity and the second cavity are respectively arranged adjacent to the third receiving cavity. The first inductor is housed in the first cavity, and the second inductor is housed in the second cavity.

7. The photovoltaic inverter as described in claim 6, characterized in that, The power module includes a first switching transistor and a second switching transistor. The first switching transistor is electrically connected between the DC input terminal and the first inductor, and the second switching transistor is electrically connected between the bus capacitor and the second inductor. The first switching transistor is located close to the first inductor, and the second switching transistor is located close to the second inductor.

8. The photovoltaic inverter as described in any one of claims 1 to 7, characterized in that, The power conversion circuit also includes multiple relays; the multiple relays are located between the circuit board and the bottom housing; The plurality of partitions includes a third partition, which separates the second accommodating cavity from the third accommodating cavity; a thermal pad is provided at one end of the third partition facing the cover, and the thermal pad is used to contact the circuit board; the plurality of relays are arranged in two rows on both sides of the thermal pad.

9. The photovoltaic inverter as described in claim 8, characterized in that, The third partition plate is also provided with a metal bracket at one end facing the cover, the heat-conducting pad is fixed to the end of the metal bracket facing the cover, and the multiple relays are distributed in two rows on both sides of the metal bracket.

10. The photovoltaic inverter as described in any one of claims 1 to 9, characterized in that, The plurality of receiving cavities also includes a fifth receiving cavity, which is disposed adjacent to the terminal panel and is located between the third receiving cavity and the second receiving cavity; The power conversion circuit further includes a second communication circuit, which is housed within the fifth accommodating cavity; The terminal panel also includes a second communication terminal that extends through the terminal panel. One end of the second communication terminal that extends into the fifth receiving cavity is electrically connected to the second communication circuit. The second communication terminal is used to serially transmit data to an external device.

11. The photovoltaic inverter as described in any one of claims 1 to 10, characterized in that, The photovoltaic inverter also includes a switch, which is disposed in the housing and connected between the DC input terminal and the first inductor. The switch is used to connect or disconnect the electrical connection between the photovoltaic module and the power conversion circuit.

12. The photovoltaic inverter as described in any one of claims 1 to 11, characterized in that, The circuit board is provided with a surface mount resistor, a surface mount capacitor, and a signal indicator light on the side facing the cover. The signal indicator light is used to indicate the working status of the photovoltaic inverter.

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