Patent Publication Number: US-2023164962-A1

Title: Heat Dissipation Apparatus, Inverter, and Electronic Device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2021/107059, filed on Jul. 19, 2021 which claims priority to Chinese Patent Application No. 202010725843.3, filed on Jul. 24, 2020. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This application relates to the field of heat dissipation technologies, and in particular, to a heat dissipation apparatus, an inverter, and an electronic device. 
     BACKGROUND 
     A photovoltaic inverter is mainly configured to invert direct current power generated by a photovoltaic panel into alternating current power that can access a power grid. The photovoltaic inverter may be applied to a ground (a power station), a rooftop (for commercial use and household use), and a water surface (a fishery-solar hybrid project (system)). When applied to a ground, the photovoltaic inverter is usually installed vertically by using a support. On a rooftop, to avoid shading a surrounding photovoltaic panel from sunlight, the photovoltaic inverter is usually installed obliquely at a small angle. On a water surface in a fishery-solar hybrid project (system), the photovoltaic inverter is usually installed on a floating body floating on water, and is usually installed horizontally to avoid blocking light and stabilize a center of gravity. 
     Application scenario environments of photovoltaic inverters are complex and harsh, and installation and maintenance are inconvenient. Therefore, natural heat dissipation is usually adopted. A conventional heat sink for natural heat dissipation is located on a back side of a chassis of an inverter. When the inverter is installed horizontally or obliquely at a small angle on a rooftop or in a fishery-solar hybrid project (system) scenario, a heat dissipation capability is severely attenuated (by 20% to 30%). As a result, the inverter is derated (an electric energy yield decreases) in advance under high temperature. 
     How to improve the heat dissipation capability of the heat sink and reduce difficulty of installation and maintenance should be a research and development direction of the industry. 
     SUMMARY 
     This application provides a heat dissipation apparatus, where thermal energy generated by an inverter is conducted from a main heat sink to an extra heat sink by using a split heat dissipation apparatus design. The main heat sink is installed on the inverter. The extra heat sink and the inverter are separately transported. The extra heat sink and the inverter provided with the main heat sink are assembled on site. Disposition of the main heat sink and the extra heat sink improves a heat dissipation capability, and such a split structure realizes flexible configuration and facilitates transportation, installation, and disassembly. 
     According to a first aspect, this application provides a heat dissipation apparatus. The heat dissipation apparatus includes a main heat sink, an extra heat sink, and a heat conducting element. The main heat sink includes a main substrate and a main fin. One end of the main fin is connected to the main substrate. The extra heat sink is located at an end of the main fin farther away from the main substrate. The extra heat sink is detachably connected to the main heat sink. The heat conducting element extends from the main substrate to the extra heat sink, so as to transfer heat between the main substrate and the extra heat sink. 
     In this application, the heat dissipation apparatus is designed as a split structure, and the split heat dissipation apparatus includes the main heat sink, the extra heat sink, and the heat conducting element. It can be understood that the heat conducting element and the main heat sink may be an integral structure, where the heat conducting element is a part of the main heat sink; or the heat conducting element and the extra heat sink may be an integral structure. The heat dissipation apparatus in this application may be applied to an inverter. The main heat sink is installed on a chassis of the inverter to form an integral whole with the inverter. Then, the extra heat sink and the inverter provided with the main heat sink are separately transported, and are installed on site. Specifically, the extra heat sink is first installed on a ground, a rooftop, a water surface, or the like, and then the inverter provided with the main heat sink is installed on the extra heat sink. Thermal energy generated by a heating element of the inverter is first conducted to the main heat sink. Part of the thermal energy is dissipated through the main heat sink. The other part of the thermal energy is conducted from the main heat sink to the extra heat sink through the heat conducting element, so as to be dissipated. A dual heat dissipation function of the main heat sink and the extra heat sink improves a heat dissipation capability of the heat dissipation apparatus and improves heat dissipation efficiency. In addition, because the extra heat sink and the inverter provided with the main heat sink are detachably connected, flexible configuration is implemented, so that the extra heat sink and the inverter provided with the main heat sink can be separately transported and be assembled on site. An overall weight and size of the inverter are not increased, and a problem of difficult transportation, installation, and maintenance is avoided. 
     In a possible implementation, a coefficient of thermal conductivity of the heat conducting element is greater than a coefficient of thermal conductivity of the extra heat sink, and the coefficient of thermal conductivity of the heat conducting element is greater than a coefficient of thermal conductivity of the main heat sink. The heat conducting element mainly performs a function of conducting thermal energy between the main substrate and the extra heat sink, and usually needs a comparatively large coefficient of thermal conductivity. A material of the main heat sink and the extra heat sink may be aluminum. The heat conducting element may be made of copper or another material with a large coefficient of thermal conductivity. 
     In a possible implementation, a contact area between the heat conducting element and the extra heat sink is greater than a contact area between the heat conducting element and the main substrate (“contact” herein may be direct contact or indirect contact, that is, regions between the heat conducting element and the extra heat sink and between the heat conducting element and the main substrate may be filled with another heat conducting material). Specifically, the heat conducting element includes a first thermal conductive interface and a second thermal conductive interface. The first thermal conductive interface is connected to the main substrate of the main heat sink. The second thermal conductive interface is connected to an extra substrate of the extra heat sink. A size of the second thermal conductive interface is greater than a size of the first thermal conductive interface. The heat conducting element is configured to conduct, to the extra heat sink, thermal energy conducted to the main heat sink. As the size of the second thermal conductive interface is set to be greater than the size of the first thermal conductive interface, a contact area between the heat conducting element and the extra substrate is increased, which helps improve heat conduction efficiency and increase rapid diffusion and transfer of thermal energy on the extra substrate. 
     In a possible implementation, the heat conducting element includes a main body, a first plate body, and a second plate body. The main body is in contact with the main substrate. The first plate body and the second plate body are in contact with the extra heat sink. Both the first plate body and the second plate body bend and extend from an end of the main body farther away from the main substrate, and extension directions thereof are different. In other words, the heat conducting element may have a T-shaped structure, that is, the main body of the heat conducting element may be perpendicular to the first plate body and the second plate body. In another implementation, the main body of the heat conducting element may be alternatively disposed obliquely at a specific angle with the first plate body and the second plate body. The heat conducting element is connected to the main substrate of the main heat sink and the extra substrate of the extra heat sink, to conduct, to the extra heat sink, part of thermal energy conducted to the main heat sink. In this way, the dual heat dissipation function of the main heat sink and the extra heat sink is implemented, so as to improve the heat dissipation capability of the heat dissipation apparatus. 
     In a possible implementation, the heat conducting element includes a main body and a connecting part. The main body is in contact with the main substrate. The connecting part is in contact with the extra heat sink. One end of the connecting part is connected to an end of the main body farther away from the main substrate. An included angle is formed between the main body and the connecting part. In other words, the main body and the connecting part of the heat conducting element may form an L-shaped structure, that is, the connecting part bends and extends to only one side of the main body. 
     In a possible implementation, the extra heat sink is provided with a groove, and a surface, of the heat conducting element, in contact with the extra heat sink includes a mating part that is protrusively disposed. The mating part is accommodated in the groove, and a surface of the mating part fits against an inner surface of the groove. The main heat sink and the extra heat sink can be positioned and installed through fitting between the groove and the mating part between the heat conducting element and the extra substrate. In addition, as the groove and the mating part are disposed, the contact area between the heat conducting element and the extra substrate is increased, which helps improve heat conduction efficiency. 
     In a possible implementation, an elastic element is disposed between the heat conducting element and the extra heat sink. The elastic element is configured to fill a gap between the heat conducting element and the extra heat sink. The elastic element is a graphite foam, a phase-change film, a liquid metal, thermally conductive silicone grease, or a thermally conductive gel. One end of the heat conducting element is connected to the main substrate, and the other end of the heat conducting element is connected to the extra heat sink. Elastic elements may be disposed both between the heat conducting element and the extra heat sink and between the heat conducting element and the main substrate. The elastic elements are configured to fill gaps between the heat conducting element and the extra heat sink and between the heat conducting element and the main substrate, so as to improve heat dissipation efficiency. Specifically, using the heat conducting element and the extra heat sink as an example, when the main heat sink and the extra heat sink are fixedly connected, the heat conducting element and the extra heat sink may be incapable of reaching full contact with each other due to a mechanical tolerance. In addition, when the heat conducting element and the extra heat sink reach contact with each other, even if surface flatness of the heat conducting element and the extra heat sink is good, the heat conducting element and the extra heat sink cannot reach tight contact with each other, but can only reach partial contact with each other, and there are still many extremely tiny gaps or holes between two materials. A heat conductivity of air in the gaps is comparatively poor, which increases thermal resistance and hinders a heat conduction path. Therefore, filling a region between the heat conducting element and the extra heat sink with the elastic element can fill the gaps between the heat conducting element and the extra heat sink, thereby removing air from the gaps, reducing the thermal resistance, and improving thermal energy transfer efficiency. In other words, when the main heat sink and the extra heat sink are fixedly connected, a tight contact connection can be achieved by pressing the elastic element, thereby avoiding a problem that tight contact cannot be achieved due to a mechanical tolerance and surface roughness. 
     In another implementation, alternatively, connections between the heat conducting element and the extra heat sink and between the heat conducting element and the main substrate may be direct thermal connections. 
     In a possible implementation, the heat conducting element includes a cavity. A phase-change medium is disposed in the cavity, and the thermal energy is conducted from the main heat sink to the extra heat sink through the phase-change medium. To improve a heat conduction capability of the heat conducting element, the phase-change medium may be disposed in the heat conducting element. The phase-change medium may be water or the like. Specifically, the heat conducting element may be a heat pipe, a vapor chamber, or the like. The heat conducting element further includes a capillary structure. The capillary structure is located on an inner wall of the heat conducting element. The phase-change medium is located in the cavity of the heat conducting element. A region, of the heat conducting element, in contact with the main substrate absorbs heat, so that the phase-change medium in the heat conducting element is gasified by heat, that is, the water changes from liquid to gas. The gas flows in the cavity to another region of the heat conducting element. In a region, of the heat conducting element, in contact with the extra substrate, because a temperature is comparatively low, the gas is liquefied into liquid, and releases thermal energy at the same time. The thermal energy is conducted to the extra substrate, and the liquid is attracted to the capillary structure and transmitted to a side of the main substrate through the capillary structure. In this way, gas-liquid two-phase cycling is formed, thereby implementing rapid conduction of thermal energy, and improving heat conduction efficiency of the heat conducting element. 
     In a possible implementation, the extra heat sink includes an extra substrate, and a gap is formed between the main fin and the extra substrate. The main fin and the extra substrate are not in contact with each other. In other words, the gap is disposed between the main fin and the extra substrate. In this way, air in a ventilation duct formed by adjacent main fins can be exchanged through the gap between the main fin and the extra substrate. That is, air in the ventilation duct formed by two adjacent main fins is circulating, and hot and cold air can be rapidly exchanged, which helps improve heat dissipation efficiency. 
     In a possible implementation, there are a plurality of main fins. The plurality of main fins are arranged side by side along a first direction. A thickness of the heat conducting element and a thickness of the main heat sink are dimensions in the first direction. The thickness of the heat conducting element is greater than the thickness of the main fin. A function of the main fin is to dissipate heat. A heat dissipation effect of the main fin is related to an area of the main fin, and is not quite related to the thickness of the main fin in the first direction. Therefore, to reduce a weight of the main heat sink, the main fin is usually comparatively thin. A function of the heat conducting element is to conduct heat. The thickness of the heat conducting element being greater than the thickness of the main fin facilitates heat conduction, thereby improving heat conduction efficiency. 
     In a possible implementation, a suspension element is disposed on the main substrate, and the suspension element is detachably connected to the extra heat sink. There are a plurality of main fins, and the plurality of main fins are arranged side by side along a first direction. The suspension element and the plurality of main fins are disposed side by side along the first direction. The suspension element may be located at an edge of the main substrate (that is, the main fins are disposed on only one side of the suspension element). Alternatively, the suspension element may be located at a non-edge location on the main substrate, in other words, the suspension element is located between two adjacent main fins (that is, the main fins are disposed on both sides of the suspension element). One end of the suspension element is connected to the main substrate (the suspension element and the main substrate may be an integral structure). The other end of the suspension element is detachably connected to the extra heat sink. Specifically, the end, of the suspension element, connected to the extra heat sink is provided with a clip. During installation, the extra heat sink is first installed on a ground, a rooftop, a water surface, or the like, and then the inverter provided with the main heat sink is pre-positioned and installed on the extra heat sink by using the suspension element (the suspension element may be a mounting ear, and one end of the mounting ear may be provided with a clip structure), thereby implementing preliminary installation of the main heat sink and the extra heat sink. 
     In another implementation, alternatively, the main heat sink and the extra heat sink may be fixedly connected to each other without using a suspension element. For example, the main substrate is provided with a first mounting hole, and the extra substrate is provided with a second mounting hole. The first mounting hole and the second mounting hole are correspondingly disposed. During installation, a screw sequentially passes through the second mounting hole in the extra substrate and the first mounting hole in the main substrate, so as to implement a detachable connection between the main heat sink and the extra heat sink. In addition, because the main heat sink and the extra heat sink are positioned and installed through the correspondingly disposed first mounting hole and second mounting hole, a problem of skew installation and center-of-gravity instability of the heat dissipation apparatus is avoided. 
     Similarly, the first mounting hole may be located at an edge of the main substrate, and correspondingly, the second mounting hole is located at an edge of the extra substrate; or the first mounting hole may be located between adjacent main fins, and correspondingly, the second mounting hole is located between adjacent extra fins. 
     In a possible implementation, the extra heat sink includes an extra substrate, and the extra substrate and the heat conducting element are connected to each other by using a fastener. The fastener may be a detachable structure such as a screw, a bolt, or a clip. After the main heat sink and the extra heat sink are preliminarily positioned and installed by using the suspension element, fastening of the main heat sink and the extra heat sink may not be very stable due to a mechanical tolerance or a fastening structure of the heat sink. To increase overall stability of the heat dissipation apparatus, the heat conducting element and the extra substrate may be fixedly connected by using the fastener, thereby implementing a more stable connection between the main heat sink and the extra heat sink. 
     In a possible implementation, the heat conducting element and the main substrate of the main heat sink are an integral structure, and the heat conducting element is detachably connected to the extra heat sink. Heat conduction is implemented between the main heat sink and the extra heat sink through the heat conducting element. One end of the heat conducting element is connected to the main substrate, and the other end of the heat conducting element is connected to the extra substrate. 
     In a possible implementation, a surface, of the extra heat sink, facing the main substrate is provided with a sliding slot; a surface, of the heat conducting element, in contact with the extra substrate is provided with a slider; and the slider is slidably installed in the sliding slot. The main heat sink and the extra heat sink can be detachably connected through slidable mating between the sliding slot on the extra heat sink and the slider on the heat conducting element. 
     In a possible implementation, the extra heat sink is provided with a fastening hole, a surface, of the heat conducting element, in contact with the extra heat sink is provided with a fastening element, and the fastening element is detachably inserted into the fastening hole. The main heat sink and the extra heat sink can be detachably connected through tight fastening between the fastening hole on the extra heat sink and the fastening element on the heat conducting element. 
     In a possible implementation, the heat conducting element and the extra heat sink are an integral structure, and the heat conducting element is detachably connected to the main substrate. 
     In a possible implementation, a first cavity is disposed in the heat conducting element, a second cavity is disposed in the extra heat sink, the first cavity communicates with the second cavity, and a phase-change medium is disposed in both the first cavity and the second cavity. The heat conducting element and the extra heat sink may be an integral structure, and the first cavity communicates with the second cavity, thereby forming an integral heat conducting element provided with the phase-change medium, so as to implement rapid heat conduction. 
     In a possible implementation, a surface, of the main substrate, facing the extra heat sink is provided with a sliding slot; a surface, of the heat conducting element, in contact with the main substrate is provided with a slider; and the slider is slidably installed in the sliding slot. The main heat sink and the extra heat sink can be detachably connected through slidable mating between the sliding slot on the main substrate and the slider on the heat conducting element. 
     In a possible implementation, the main substrate is provided with a fastening hole, a surface, of the heat conducting element, in contact with the main substrate is provided with a fastening element, and the fastening element is detachably inserted into the fastening hole. The main heat sink and the extra heat sink can be detachably connected through tight fastening between the fastening hole in the main substrate and the fastening element on the heat conducting element. 
     In another implementation, the heat conducting element, the main heat sink, and the extra heat sink may all be separate structures, and the heat conducting element may be fastened to the main substrate of the main heat sink and the extra substrate of the extra heat sink in a manner such as insertion or bonding, thereby implementing flexible configuration of the main heat sink and the extra heat sink. 
     In a possible implementation, the heat dissipation apparatus further includes an auxiliary heat sink, the auxiliary heat sink is connected to the extra heat sink, and the auxiliary heat sink and the extra heat sink together surround the main heat sink partially. Specifically, the main fin includes a first end part, a second end part, and a side part located between the first end part and the second end part. The first end part is connected to the main substrate, and the auxiliary heat sink is located at the side part of the main fin. The auxiliary heat sink is disposed on the extra heat sink, thereby adding a heat dissipation means, so that heat dissipation efficiency can be improved. There may be one auxiliary heat sink, and the auxiliary heat sink is located on one side of the extra heat sink. Alternatively, there may be two auxiliary heat sinks, and the two auxiliary heat sinks are distributed opposite each other on two sides of the extra heat sink. 
     In a possible implementation, a gap is disposed between the auxiliary heat sink and the main heat sink. Disposing the gap between the auxiliary heat sink and the main heat sink facilitates air circulation, thereby improving heat dissipation efficiency. 
     In a possible implementation, an auxiliary substrate of the auxiliary heat sink and the extra substrate may be fixedly connected in a manner such as friction stir welding, and a split structure facilitates transportation; or the auxiliary heat sink and the extra heat sink are an integral structure, which simplifies an installation process. 
     In a possible implementation, an overall size of the extra heat sink may be extended to be the same as a size of the chassis. When the size of the extra heat sink is comparatively large, a heat dissipation area can be increased, thereby effectively improving heat dissipation. When the size of the extra heat sink is set to be comparatively small, the entire heat dissipation apparatus can be thinned. 
     In a possible implementation, the extra heat sink includes an extra substrate, an extra fin, and a supporting element. A root of the supporting element is connected to the extra substrate. A free end of the supporting element is farther away from the extra substrate. A perpendicular distance between the root of the supporting element and the free end of the supporting element is a height of the supporting element. A root of the extra fin is connected to the extra substrate. A free end of the extra fin is farther away from the extra substrate. A perpendicular distance between the root of the extra fin and the free end of the extra fin is a height of the extra fin. The height of the supporting element is greater than the height of the extra fin. The height of the supporting element and the height of the extra fin are dimensions of the supporting element and the extra fin at corresponding locations, and the height of the supporting element is greater than the height of the extra fin. Therefore, during installation, the supporting element is in contact with a ground or the like, and the extra fin is not in contact with the ground, that is, there is a gap between the extra fin and the ground. This facilitates air circulation, thereby improving heat dissipation efficiency. The supporting element may be located at an edge of the extra substrate (that is, the extra fin is disposed on only one side of the supporting element). Alternatively, the supporting element may be located at a non-edge location on the extra substrate, in other words, the supporting element is located between two adjacent extra fins (that is, the extra fins are disposed on both sides of the supporting element). The supporting element and the extra substrate may be an integral structure, which simplifies an installation process. A quantity of supporting elements is not limited. There may be two supporting elements. To stabilize a center of gravity during installation of the heat dissipation apparatus, the two supporting elements may be symmetrically disposed. In another implementation, alternatively, the quantity of supporting elements may be 3, 4, or the like, to increase installation stability of the heat dissipation apparatus. 
     In a possible implementation, the free end of the supporting element is inclined relative to a plane on which the extra substrate is located. It can be understood that a range of an inclination angle is greater than or equal to 10° and less than 90°. When the inclination angle is less than 10°, the inclination angle is excessively small, and heat dissipation efficiency cannot be effectively improved. When the inclination angle is greater than or equal to 90°, it is equivalent to a case that the heat dissipation apparatus is vertically installed or reversely installed. When the heat dissipation apparatus is horizontally installed (for example, when an installation carrier is a rooftop or a water surface, the heat dissipation apparatus is usually located on the rooftop or the water surface, and the inverter is located on a side of the heat dissipation apparatus facing away from the rooftop or the water surface, that is, the inverter is located on an upper side of the heat dissipation apparatus), during natural heat dissipation of the heat dissipation apparatus, hot air in the heat dissipation apparatus is blocked by the upper-side inverter in a process of rising, and cannot be effectively dissipated, but can only be dissipated through two side ends of a horizontal ventilation duct. As a result, the heat dissipation capability of the heat dissipation apparatus is severely attenuated (the heat dissipation capability is attenuated by 20% to 30%). If thermal energy generated by the inverter cannot be dissipated in a timely manner, performance of the inverter is affected, leading to reduction of an electric energy yield of the inverter. In this implementation, the free end of the supporting element is disposed obliquely relative to the plane on which the extra substrate is located (it can be understood that a perpendicular projection of the supporting element in a direction perpendicular to the extra substrate may be triangular or trapezoidal), so that there is a specific inclination angle between the extra fin and the rooftop or the water surface. In this way, hot air can be effectively dissipated through the fin, thereby improving exchange efficiency of hot and cold air, and weakening impact on the heat dissipation capability of the heat dissipation apparatus that is caused by the inverter blocking the hot air. This implements effective heat dissipation when the heat dissipation apparatus is horizontally installed. 
     In a possible implementation, the extra heat sink includes a plurality of extra fins, the plurality of extra fins are disposed side by side on the extra substrate, and a surface, of each extra fin, farther away from the extra substrate is disposed obliquely relative to the extra substrate. In this implementation, surfaces, of all the extra fins, father away from the extra substrate are disposed obliquely relative to the extra substrate (it can be understood that a perpendicular projection of the extra fin in a direction perpendicular to the extra substrate may be triangular or trapezoidal), so that exchange of hot and cold air can be increased, and there is a specific inclination angle between the extra fin and a rooftop or a water surface. In this way, hot air can be effectively dissipated through the inclined fins, thereby improving exchange efficiency of hot and cold air, and weakening impact on the heat dissipation capability of the heat dissipation apparatus that is caused by the inverter blocking the hot air. In addition, because all the extra fins in this implementation are obliquely disposed, a heat dissipation area is increased, thereby implementing effective heat dissipation when the heat dissipation apparatus is horizontally installed. 
     In a possible implementation, an inclination angle is disposed between the extra substrate and the surface, of each extra fin, farther away from the extra substrate, and the inclination angle is greater than or equal to 10° and less than 90°. When the inclination angle is less than 10°, the inclination angle is excessively small, and heat dissipation efficiency cannot be effectively improved. When the inclination angle is greater than or equal to 90°, it is equivalent to a case that the heat dissipation apparatus is vertically or reversely installed. 
     According to a second aspect, this application provides an inverter, including a chassis, a heating element, and the heat dissipation apparatus according to any one of the foregoing implementations. The heating element is located in the chassis. The main substrate is fastened to the chassis. A first region is disposed on the main substrate, and the heating element is correspondingly disposed in the first region. At least one heat conducting element is correspondingly disposed on a side of each first region facing away from the heating element. 
     According to a third aspect, this application provides an electronic device, including a heating element and the heat dissipation apparatus according to any one of the foregoing implementations. The heating element is connected to the heat dissipation apparatus, and thermal energy of the heating element is conducted to the heat dissipation apparatus. 
     The split heat dissipation apparatus in this application has a good heat dissipation capability, and the dual heat dissipation function of the main heat sink and the extra heat sink improves heat dissipation efficiency of the heat dissipation apparatus. In addition, because the extra heat sink and the inverter provided with the main heat sink are detachably connected, flexible configuration is implemented, so that the extra heat sink and the inverter provided with the main heat sink can be separately transported and be assembled on site. The overall weight and size of the inverter are not increased, and the problem of difficult transportation, installation, and maintenance is avoided. The heat dissipation apparatus in this application has a simple structure and is convenient to install, and the overall weight and size of the inverter are not increased, which facilitates transportation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To describe technical solutions in embodiments of this application or in the background more clearly, the following describes the accompanying drawings used in embodiments of this application or in the background. 
         FIG.  1    is a schematic diagram of an application environment of an inverter according to an implementation of this application; 
         FIG.  2   a    is a schematic diagram of installing an inverter on a ground according to an implementation of this application; 
         FIG.  2   b    is a schematic diagram of installing an inverter on a rooftop according to an implementation of this application; 
         FIG.  2 C  is a schematic diagram of installing an inverter on a water surface according to an implementation of this application; 
         FIG.  3    is a schematic diagram of an overall structure of a heat dissipation apparatus according to an implementation of this application; 
         FIG.  4    is a top view of a heat dissipation apparatus according to an implementation of this application; 
         FIG.  5    is a sectional view of a heat dissipation apparatus according to an implementation of this application; 
         FIG.  6    is a schematic diagram of a structure of a heat conducting element according to an implementation of this application; 
         FIG.  7    is a schematic diagram of a structure of a heat conducting element according to another implementation of this application; 
         FIG.  8    is a schematic diagram of an internal structure of a heat conducting element according to an implementation of this application; 
         FIG.  9   a    is a schematic diagram of a structure of detachably connecting a main heat sink and an extra heat sink by using a heat conducting element according to an implementation of this application; 
         FIG.  9   b    is a schematic diagram of a structure of detachably connecting a main heat sink and an extra heat sink by using a heat conducting element according to another implementation of this application; 
         FIG.  9   c    is a schematic diagram of a structure of detachably connecting a main heat sink and an extra heat sink by using a heat conducting element according to another implementation of this application; 
         FIG.  9   d    is a schematic diagram of a structure of detachably connecting a main heat sink and an extra heat sink by using a heat conducting element according to another implementation of this application; 
         FIG.  9   e    is a schematic diagram of a structure of a heat conducting element according to an implementation of this application; 
         FIG.  10    is a schematic diagram of an overall structure of a heat dissipation apparatus according to another implementation of this application; 
         FIG.  11    is a top view of a heat dissipation apparatus according to another implementation of this application; 
         FIG.  12    is a sectional view of a heat dissipation apparatus according to another implementation of this application; 
         FIG.  13    is a schematic diagram of a structure of a heat dissipation apparatus installed on a horizontal plane according to an implementation of this application; 
         FIG.  14    is a schematic diagram of a structure of a heat dissipation apparatus installed on an inclined plane according to an implementation of this application; 
         FIG.  15    is a schematic diagram of an overall structure of a heat dissipation apparatus according to another implementation of this application; 
         FIG.  16    is a top view of a heat dissipation apparatus according to another implementation of this application; 
         FIG.  17    is a sectional view of a heat dissipation apparatus according to another implementation of this application; 
         FIG.  18    is a schematic diagram of a structure of a heat dissipation apparatus installed on a horizontal plane according to another implementation of this application; 
         FIG.  19    is a schematic diagram of a structure of a heat dissipation apparatus installed on an inclined plane according to another implementation of this application; 
         FIG.  20    is a schematic diagram of an overall structure of a heat dissipation apparatus according to another implementation of this application; 
         FIG.  21    is a top view of a heat dissipation apparatus according to another implementation of this application; 
         FIG.  22    is a sectional view of a heat dissipation apparatus according to another implementation of this application; 
         FIG.  23    is a schematic diagram of a fin shape structure of an extra heat sink according to an implementation of this application; and 
         FIG.  24    is a schematic diagram of a fin shape structure of an extra heat sink according to an implementation of this application. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     The following clearly describes specific implementations of this application with reference to accompanying drawings. 
     This application provides a heat dissipation apparatus, an inverter, and an electronic device. The inverter is mainly configured to invert direct current power generated by a photovoltaic panel into alternating current power that can access a power grid. The electronic device may be an inverter, or may be another device that needs heat dissipation.  FIG.  1    is a schematic diagram of an environment in which an inverter is applied to a photovoltaic power generation system. A photovoltaic module  30  converts solar energy into direct current energy. The inverter  10  converts the direct current energy generated by the photovoltaic module  30  into alternating current energy. The alternating current energy accesses a power grid  50  through a power distribution function of an alternating current power distribution cabinet  40 , so as to be used by a user. 
       FIG.  2   a   ,  FIG.  2   b   , and  FIG.  2   c    are schematic diagrams of installing an inverter on a ground, a rooftop, and a water surface, respectively. Referring to  FIG.  2   a   , when applied to a ground, the inverter  10  is vertically installed on a ground  112  by using a support in. A heat dissipation apparatus (not shown in  FIG.  2   a   ) is disposed closer to the support iii, that is, the heat dissipation apparatus is located between the inverter  10  and the support  111 . Referring to  FIG.  2   b   , when applied to a rooftop, the inverter  10  is usually installed obliquely at a small angle on a rooftop  113 , to avoid shading a surrounding photovoltaic panel (not shown in  FIG.  2   b   ) from sunlight. A heat dissipation apparatus (not shown in  FIG.  2   b   ) is installed closer to the rooftop  113 , that is, the heat dissipation apparatus is located between the inverter  10  and the rooftop  113 . Referring to  FIG.  2   c   , when applied to a water surface, the inverter  10  is usually installed on a floating body  114  on water in a fishery-solar hybrid project (system), and the inverter  10  is horizontally installed to avoid blocking light and stabilize a center of gravity. A heat dissipation apparatus (not shown in  FIG.  2   c   ) is installed closer to the floating body  114  on water, that is, the heat dissipation apparatus is located between the inverter  10  and the floating body  114 . 
       FIG.  3   ,  FIG.  4   , and  FIG.  5    are respectively a schematic diagram of an overall structure, a top view, and a sectional view of a heat dissipation apparatus. The inverter  10  generates thermal energy in a running process. If heat dissipation cannot be performed on the inverter  10  in a timely manner, an electric energy yield of the inverter  10  is reduced, and even the inverter  10  cannot work normally. Therefore, a heat dissipation apparatus  20  is of great importance to the inverter  10 . The heat dissipation apparatus  20  includes a main heat sink  21 , an extra heat sink  22 , and a heat conducting element  23 . The main heat sink  21  includes a main substrate  211  and a main fin  212 . The extra heat sink  22  includes an extra substrate  221  and an extra fin  222 . One end of the main fin  212  is connected to the main substrate  211 . The extra heat sink  22  is located at an end of the main fin  212  farther away from the main substrate  211 . The extra heat sink  22  is detachably connected to the main heat sink  21 . The heat conducting element  23  extends from the main substrate  211  to the extra heat sink  22 , to transfer heat between the main substrate  211  and the extra heat sink  22 . 
     In this application, the heat dissipation apparatus  20  is designed as a split structure, and the split heat dissipation apparatus  20  includes the main heat sink  21 , the extra heat sink  22 , and the heat conducting element  23 . It can be understood that the heat conducting element  23  and the main heat sink  21  may be an integral structure, where the heat conducting element  23  is a part of the main heat sink  21 ; or the heat conducting element  23  and the extra heat sink  22  may be an integral structure. The main heat sink  21  is installed on the inverter  10  to form an integral whole with the inverter  10 . Then, the extra heat sink  22  and the inverter  10  provided with the main heat sink  21  are separately transported, and are installed on site. Specifically, the extra heat sink  22  is first installed on a ground, a rooftop, a water surface, or the like, and then the inverter  10  provided with the main heat sink  21  is installed on the extra heat sink  22 . Thermal energy generated by the inverter  10  is first conducted to the main heat sink  21 . Part of the thermal energy is dissipated through the main heat sink  21 . The other part of the thermal energy is conducted from the main heat sink  21  to the extra heat sink  22  through the heat conducting element  23 , so as to be dissipated. A dual heat dissipation function of the main heat sink  21  and the extra heat sink  22  improves a heat dissipation capability of the heat dissipation apparatus  20  and improves heat dissipation efficiency. In addition, because the extra heat sink  22  and the inverter  10  provided with the main heat sink  21  can be separately transported and be assembled on site, flexible configuration is implemented, so that an overall weight and size of the inverter  10  are not increased, and a problem of difficult transportation, installation, and maintenance is avoided. 
     One end of the heat conducting element  23  is connected to the main heat sink  21 , and the other end is connected to the extra heat sink  22 . A structure of the heat conducting element  23  includes but is not limited to the following two solutions. 
     In a first solution, referring to  FIG.  4   , the heat conducting element  23  includes a main body  231 , a first plate body  2321 , and a second plate body  2322 . The main body  231  is in contact with the main substrate  211 . The first plate body  2321  and the second plate body  2322  are in contact with the extra substrate  221  of the extra heat sink  22 . Both the first plate body  2321  and the second plate body  2322  bend and extend from an end of the main body  231  farther away from the main substrate  211 , and extension directions thereof are different. In other words, the heat conducting element  23  may have a T-shaped structure, where the first plate body  2321  and the second plate body  2322  extend in opposite directions. The main body  231  may be perpendicular to the first plate body  2321  and the second plate body  2322 , thereby forming the T-shaped structure. In another implementation, the main body  231  of the heat conducting element  23  may be alternatively disposed obliquely at a specific angle with the first plate body  2321  and the second plate body  2322 . Specifically, the bodies are disposed based on a structure of the heat dissipation apparatus  20  and a heat dissipation requirement. 
     In a second solution, referring to  FIG.  6   , the heat conducting element  23  includes a main body  231  and a connecting part  232 . The main body  231  is in contact with the main substrate  211 . The connecting part  232  is in contact with the extra substrate  221 . One end of the connecting part  232  is connected to an end of the main body  231  farther away from the main substrate  211 . An included angle is formed between the main body  231  and the connecting part  232 . In other words, the main body  231  and the connecting part  232  of the heat conducting element  23  may form an L-shaped structure, that is, the connecting part  232  bends and extends to only one side of the main body  231 . When a distance between two adjacent heat conducting elements  23  is comparatively small, the heat conducting element  23  of the L-shaped structure may be used, so as to implement rapid transfer of thermal energy. 
     The heat conducting element  23  and the extra substrate  221  may be in contact with each other on a plane (referring to  FIG.  4    and  FIG.  6   ). Alternatively, the heat conducting element  23  and the extra substrate  221  may be in contact with each other through a groove. Specifically, referring to  FIG.  7   , the extra substrate  221  is provided with a groove  2211 , and a surface, of the heat conducting element  23 , in contact with the extra heat sink  22  includes a mating part  237  that is protrusively disposed. The mating part  237  is accommodated in the groove  2211 , and a surface of the mating part  237  fits against an inner surface of the groove  2211 . The main heat sink  21  and the extra heat sink  22  can be positioned and installed, between the heat conducting element  23  and the extra substrate  221 , through mating between the groove  2211  and the mating part  237 . In addition, as the groove  2211  and the mating pall  237  are disposed, a contact area between the heat conducting element  23  and the extra substrate  221  is increased, which helps improve heat conduction efficiency. The groove  2211  may be an arcuate groove, and the surface, of the mating part  237 , fitting against the groove  2211  is an arcuate surface. Such an arcuate structure increases the contact area between the heat conducting element  23  and the extra substrate  221 , thereby facilitating rapid heat conduction. 
     A main function of the heat conducting element  23  is to conduct thermal energy between the main substrate  211  and the extra heat sink  22 . Therefore, a coefficient of thermal conductivity of the heat conducting element  23  is greater than a coefficient of thermal conductivity of the extra heat sink  22 , and the coefficient of thermal conductivity of the heat conducting element  23  is greater than a coefficient of thermal conductivity of the main heat sink  21 , thereby facilitating rapid heat conduction. It can be understood that a material of the main heat sink  21  and the extra heat sink  22  may be aluminum, and the heat conducting element  23  may be made of copper or another material with a large coefficient of thermal conductivity. 
     In another implementation, alternatively, the heat conducting element  23 , the main heat sink  21 , and the extra heat sink  22  may be made of a same material, that is, coefficients of thermal conductivity of the heat conducting element  23 , the main heat sink  21 , and the extra heat sink  22  are the same. For example, the heat conducting element  23 , the main heat sink  21 , and the extra heat sink  22  may all be made of copper or aluminum. 
     When the heat conducting element  23 , the main heat sink  21 , and the extra heat sink  22  are made of a same material (that is, the coefficients of thermal conductivity thereof are the same), to improve a heat conduction effect of the heat conducting element  23 , a phase-change medium may also be disposed in the heat conducting element  23 , so as to improve a heat conduction capability of the heat conducting element  23 . Specifically, referring to  FIG.  8   , the heat conducting element  23  includes a cavity  235 , and a phase-change medium (not shown in  FIG.  8   , where the phase-change medium may be water or the like) is disposed in the cavity  235 . Thermal energy is conducted from a hot end  2361  (that is, an end closer to a heating element) of the heat conducting element  23  to a cold end  2362  (that is, an end farther away from the heating element) of the heat conducting element  23 . In other words, the thermal energy is conducted from the main heat sink  21  to the extra heat sink  22  through the phase-change medium. It can be understood that, when the coefficient of thermal conductivity of the heat conducting element  23  is greater than the coefficient of thermal conductivity of the extra heat sink  22 , and the coefficient of thermal conductivity of the heat conducting element  23  is greater than the coefficient of thermal conductivity of the main heat sink  21 , a phase-change medium may also be disposed in the heat conducting element  23  to improve a heat conduction effect of the heat conducting element  23 . 
     It can be understood that the heat conducting element  23  may be a heat pipe, a vapor chamber, or the like. The heat conducting element  23  further includes a capillary structure. The capillary structure is located on an inner wall of the heat conducting element  23 . The phase-change medium is located in the cavity  235  of the heat conducting element  23 . A region, of the heat conducting element  23 , in contact with the main substrate  211  absorbs heat, so that the phase-change medium in the heat conducting element  23  is gasified by heat, that is, the water changes from liquid to gas. The gas flows in the cavity to another region of the heat conducting element  23 . In a region, of the heat conducting element  23 , in contact with the extra substrate  221 , because a temperature is comparatively low, the gas is liquefied into liquid, and releases thermal energy at the same time. The thermal energy is conducted to the extra substrate  221 , and the liquid is attracted to the capillary structure and transmitted to a side of the main substrate  211  through the capillary structure. In this way, gas-liquid two-phase cycling is formed, thereby implementing rapid conduction of thermal energy, and improving heat conduction efficiency of the heat conducting element. 
     The contact area between the heat conducting element  23  and the extra substrate  221  is greater than a contact area between the heat conducting element  23  and the main substrate  211  (“contact” herein may be direct contact or indirect contact, that is, regions between the heat conducting element  23  and the extra heat sink  22  and between the heat conducting element  23  and the main substrate  211  may be filled with another heat conducting material). Specifically, referring to  FIG.  4    and  FIG.  6   , the heat conducting element  23  includes a first thermal conductive interface  233  and a second thermal conductive interface  234 . The first thermal conductive interface  233  is connected to the main substrate  211 . The second thermal conductive interface  234  is connected to the extra substrate  221 . A size of the second thermal conductive interface  234  is greater than a size of the first thermal conductive interface  233 . The heat conducting element  23  is configured to conduct, to the extra heat sink  22 , thermal energy conducted to the main heat sink  21 . As the size of the second thermal conductive interface  234  is set to be greater than the size of the first thermal conductive interface  233 , the contact area between the heat conducting element  23  and the extra substrate  221  is increased, which helps improve heat conduction efficiency and increase rapid diffusion and transfer of thermal energy on the extra substrate  221 . 
     Referring to  FIG.  4   , a gap is formed between the main fin  212  and the extra substrate  221 . In other words, the main fin  212  and the extra substrate  221  are not in contact with each other. In this way, air in a ventilation duct formed by two adjacent main fins  212  can be exchanged through the gap between the main fin  212  and the extra substrate  221 . That is, air in the ventilation duct formed by two adjacent main fins  212  is circulating, and hot and cold air can be rapidly exchanged, which helps improve heat dissipation efficiency. 
     In a possible implementation, there are a plurality of main fins  212 . An arrangement direction of the plurality of main fins  212  is a first direction X 1 . A thickness of the heat conducting element  23  and a thickness of the main fin  212  are dimensions in the first direction X 1 . The thickness of the heat conducting element  23  is greater than the thickness of the main fin  212 . A function of the main fin  212  is to dissipate heat. A heat dissipation effect of the main fin  212  is related to an area of the main fin  212 , and is not quite related to the thickness of the main fin  212  in the first direction. Therefore, to reduce a weight of the main heat sink  21 , the main fin  212  is usually comparatively thin. A function of the heat conducting element  23  is to conduct heat. The thickness of the heat conducting element  23  being greater than the thickness of the main fin  212  facilitates rapid conduction of thermal energy, thereby improving heat conduction efficiency. 
     The main heat sink  21  and the extra heat sink  22  are detachably connected. Referring to  FIG.  4   , a suspension element  213  is disposed on the main substrate  211  of the main heat sink  21 , and the suspension element  213  is detachably connected to the extra substrate  221  of the extra heat sink  22 . The suspension element  213  and the plurality of main fins  212  are disposed side by side along the first direction X 1 . The suspension element  213  may be located at an edge of the main substrate  211  (that is, the main fins  212  are disposed on only one side of the suspension element  213 ). Alternatively, the suspension element  213  may be located at a non-edge location on the main substrate  211 , in other words, the suspension element  213  is located between two adjacent main fins  212  (that is, the main fins  212  are disposed on both sides of the suspension element  213 ). One end of the suspension element  213  is connected to the main substrate  211  (the suspension element  213  and the main substrate  211  may be an integral structure). The other end of the suspension element  213  is detachably connected to the extra heat sink  22 . Specifically, the end, of the suspension element  213 , connected to the extra heat sink  22  is provided with a clip. During installation, the extra heat sink  22  is first installed on a ground, a rooftop, a water surface, or the like, and then the inverter  10  provided with the main heat sink  21  is pre-positioned and installed on the extra heat sink  22  by using the suspension element  213  (the suspension element  213  may be a mounting ear, and one end of the mounting ear may be provided with a clip structure), thereby implementing preliminary installation of the main heat sink  21  and the extra heat sink  22 . A quantity of suspension elements  213  is not limited, and the quantity of suspension elements  213  may be 2, 3, or the like. 
     In a possible implementation, referring to  FIG.  4   , the extra substrate  221  and the heat conducting element  23  are connected to each other by using a fastener  236  ( FIG.  4    shows merely an example in which one heat conducting element  23  is provided with the fastener  236 ; in a specific application environment, each heat conducting element  23  may be provided with a fastener  236 , and both the first plate body  2321  and the second plate body  2322  of the heat conducting element  23  may be provided with fasteners  236 ). The fastener  236  may be a detachable structure such as a screw, a bolt, or a clip. After the main heat sink  21  and the extra heat sink  22  are preliminarily positioned and installed by using the suspension element  213 , fastening of the main heat sink  21  and the extra heat sink  22  may not be very stable due to a mechanical tolerance or a fastening structure of the heat sink. To increase overall stability of the heat dissipation apparatus  20 , the heat conducting element  23  and the extra substrate  221  may be fixedly connected by using the fastener  236 , thereby implementing a more stable connection between the main heat sink  21  and the extra heat sink  22 . 
     In another implementation, alternatively, the main heat sink  21  and the extra heat sink  22  may be fixedly connected to each other without using a suspension element. For example, the main substrate  211  is provided with a first mounting hole, and the extra substrate  221  is provided with a second mounting hole. The first mounting hole and the second mounting hole are correspondingly disposed. During installation, a screw sequentially passes through the second mounting hole in the extra substrate  221  and the first mounting hole in the main substrate  211 , so as to implement a detachable connection between the main heat sink  21  and the extra heat sink  22 . In addition, because the main heat sink  21  and the extra heat sink  22  are positioned and installed through the correspondingly disposed first mounting hole and second mounting hole, a problem of skew installation and center-of-gravity instability of the heat dissipation apparatus is avoided. 
     Similarly, the first mounting hole may be located at an edge of the main substrate  211 , and correspondingly, the second mounting hole is located at an edge of the extra substrate  221 ; or the first mounting hole may be located between adjacent main fins  212 , and correspondingly, the second mounting hole is located between adjacent extra fins  222 . 
     Alternatively, the main heat sink  21  and the extra heat sink  22  may be detachably connected to each other by using the heat conducting element  23 . Manners of the detachable connection specifically include but are not limited to the following connection manners. 
     In a first manner, the heat conducting element  23  and the main substrate  211  of the main heat sink  21  are an integral structure, and the heat conducting element  23  is detachably connected to the extra substrate  221  of the extra heat sink  22 . 
     Specifically, referring to  FIG.  9   a   , a surface, of the extra substrate  221 , facing the main substrate  211  is provided with a sliding slot  2212 ; a surface, of the heat conducting element  23 , in contact with the extra substrate  221  is provided with a slider  2213 ; and the slider  2213  is slidably installed in the sliding slot  2212  and is used for the detachable connection between the main heat sink  21  and the extra heat sink  22 . The main heat sink  21  and the extra heat sink  22  can be detachably connected through slidable mating between the sliding slot  2212  on the extra substrate  221  and the slider  2213  on the heat conducting element  23 . 
     In another implementation, referring to  FIG.  9   b   , the extra substrate  221  is provided with a fastening hole  2214 , a surface, of the heat conducting element  23 , in contact with the extra substrate  221  is provided with a fastening element  2215 , and the fastening element  2215  is detachably inserted into the fastening hole  2214 . The main heat sink  21  and the extra heat sink  22  can be detachably connected through tight fastening between the fastening hole  2214  in the extra substrate  221  and the fastening element  2215  on the heat conducting element  23 . 
     In a second manner, the heat conducting element  23  and the extra substrate  221  of the extra heat sink  22  are an integral structure, and the heat conducting element  23  is detachably connected to the main substrate  211  of the main heat sink  21 . 
     Specifically, referring to  FIG.  9   c   , a surface, of the main substrate  211 , facing the extra substrate  221  is provided with a sliding slot  2212 ; a surface, of the heat conducting element  23 , in contact with the main substrate  211  is provided with a slider  2213 ; and the slider  2213  is slidably installed in the sliding slot  2212  and is used for the detachable connection between the main heat sink  21  and the extra heat sink  22 . The main heat sink  21  and the extra heat sink  22  can be stably and detachably connected through slidable mating between the sliding slot  2212  on the main substrate  211  and the slider  2213  on the heat conducting element  23 . 
     In another implementation, referring to  FIG.  9   d   , the main substrate  211  is provided with a fastening hole  2214 , a surface, of the heat conducting element  23 , in contact with the main substrate  211  is provided with a fastening element  2215 , and the fastening element  2215  is detachably inserted into the fastening hole  2214 . The main heat sink  21  and the extra heat sink  22  can be stably and detachably connected through tight fastening between the fastening hole  2214  in the main substrate  211  and the fastening element  2215  on the heat conducting element  23 . 
     Referring to  FIG.  9   e   , when the heat conducting element  23  and the extra substrate  221  are an integral structure, the heat conducting element  23  is internally provided with a cavity  235  (for differentiation, the cavity  235  is referred to as a first cavity), and the extra substrate  221  is internally provided with a second cavity  2216 . The heat conducting element  23  is butted with the extra substrate  221 , so that the first cavity (that is, the cavity  235 ) communicates with the second cavity  2216 . A phase-change medium (not shown in  FIG.  9   e   ) is disposed in both the first cavity and the second cavity  2216 . The heat conducting element  23  and the extra substrate  221  may be an integral structure, and their cavities communicate with each other, thereby forming an integral heat conducting element provided with the phase-change medium, so as to implement rapid heat conduction. 
     In another implementation, the heat conducting element  23 , the main heat sink  21 , and the extra heat sink  22  may all be separate structures, and the heat conducting element  23  may be fastened to the main substrate  211  of the main heat sink  21  and the extra substrate  221  of the extra heat sink  22  in a manner such as insertion or bonding, thereby implementing flexible configuration of the main heat sink  21  and the extra heat sink  22 . 
     Connections between the heat conducting element  23  and the extra substrate  221  and between the heat conducting element  23  and the main substrate  211  may be direct thermal connections. Alternatively, elastic elements  27  may be disposed between the heat conducting element  23  and the extra substrate  221  and between the heat conducting element  23  and the main substrate  211 , to improve heat dissipation efficiency. Referring to  FIG.  9   a   , the elastic element  27  may be a graphite foam, a phase-change film, thermally conductive silicone grease, a thermally conductive gel, a liquid metal, or the like. One end of the heat conducting element  23  is connected to the main substrate  211 , and the other end of the heat conducting element  23  is connected to the extra heat sink  22 . Elastic elements  27  may be disposed both between the heat conducting element  23  and the extra heat sink  22  and between the heat conducting element  23  and the main substrate  211 . The elastic elements  27  are configured to fill gaps between the heat conducting element  23  and the extra heat sink  22  and between the heat conducting element  23  and the main substrate  211 , so as to improve heat dissipation efficiency. Specifically, using the heat conducting element  23  and the extra heat sink  22  as an example, when the main heat sink  21  and the extra heat sink  22  are fixedly connected, the heat conducting element  23  and the extra heat sink  22  may be incapable of reaching full contact with each other due to a mechanical tolerance. In addition, when the heat conducting element  23  and the extra substrate  221  reach contact with each other, even if surface flatness of the heat conducting element  23  and the extra substrate  221  is good, the heat conducting element and the extra substrate cannot reach fully tight contact with each other, but can only reach partial contact with each other, and there are still many extremely tiny gaps or holes between two materials. A heat conductivity of air in the gaps is comparatively poor, which increases thermal resistance and hinders a heat conduction path. Therefore, filling a region between the heat conducting element  23  and the extra substrate  221  with the elastic element  27  can fill the gaps between the heat conducting element  23  and the extra substrate  221 , thereby removing air from the gaps, reducing the thermal resistance, and improving thermal energy transfer efficiency. In other words, when the main heat sink  21  and the extra heat sink  22  are fixedly connected, a tight contact connection can be achieved by pressing the elastic element  27 , thereby avoiding a problem that full contact cannot be achieved due to a mechanical tolerance and surface roughness. 
     In a possible implementation, an overall size of the extra heat sink  22  may be extended to be the same as the size of the inverter  10 . When the size of the extra heat sink  22  is comparatively large, a heat dissipation area can be increased, thereby effectively improving heat dissipation. When the size of the extra heat sink  22  is set to be comparatively small, the entire heat dissipation apparatus  20  can be thinned. 
     Referring to  FIG.  4   , the inverter  10  includes a chassis no and a heating element  101 . The heating element  101  is located in the chassis no. The main heat sink  21  is installed on the chassis no. The heating element  101  is connected to a side of the main heat sink  21  facing the chassis no. The extra heat sink  22  is connected to a side of the main heat sink  21  facing away from the chassis no. The heat conducting element  23  is located between the main heat sink  21  and the extra heat sink  22 . The heating element  101  may be fastened to the main substrate  211  of the main heat sink  21  by using a screw, a bolt, a clip, or the like. The heating element  101  may be a device that generates thermal energy, such as a power semiconductor device. It can be understood that the chassis  110  may be a structure whose one side is provided with an opening. When the main heat sink  21  is installed, the main substrate  211  of the main heat sink  21  blocks a location of the opening of the chassis  110 , and the heating element  101  is directly fastened to the main substrate  211 . In another implementation, alternatively, the chassis  110  may be an intact housing structure, and the main heat sink  21  fits against a surface of the chassis  110 . 
     A first region  2111  is disposed on the main substrate  211 , and the heating element  101  is correspondingly disposed in the first region  2111 . At least one heat conducting element  23  is correspondingly disposed on a side of each first region  2111  facing away from the heating element  101 . The heating element  23  is located in the first region  2111 , and thermal energy generated by the heating element  23  is also mainly located in the first region  2111 . Therefore, the heat conducting element  23  is also mainly disposed in the first region  2111  correspondingly, so as to help improve heat conduction efficiency, so that the thermal energy generated by the heating element  101  can be concentratedly and rapidly transferred to the extra heat sink  22 . Each first region  2111  is connected to at least one heat conducting element  23 . To improve heat conduction efficiency, a quantity of heat conducting elements  23  corresponding to each first region  2111  may also be 2, 3, or the like. 
       FIG.  10   ,  FIG.  11   , and  FIG.  12    are respectively a diagram of an overall structure, a top view, and a sectional view of the heat dissipation apparatus according to a possible implementation. A supporting element  2217  is disposed on the extra substrate  221 . A root of the supporting element  2217  (to be distinguished from a root of the extra fin, the root of the supporting element  2217  is referred to as a first root  2218 ) is connected to the extra substrate  221 . A free end of the supporting element  2217  (to be distinguished from a free end of the extra fin, the free end of the supporting element  2217  is referred to as a first free end  2219 ) is farther away from the extra substrate  221 . A perpendicular distance between the first root  2218  of the supporting element  2217  and the first free end  2219  of the supporting element  2217  is a height of the supporting element  2217 . A root (referred to as a second root  2221 ) of the extra fin  222  is connected to the extra substrate  221 . A free end (referred to as a second free end  2222 ) of the extra fin  222  is farther away from the extra substrate  221 . A perpendicular distance between the second root  2221  of the extra fin  222  and the second free end  2222  of the extra fin  222  is a height of the extra fin  222 . The height of the supporting element  2217  is greater than the height of the extra fin  222 . The height of the supporting element  2217  and the height of the extra fin  222  are dimensions of the supporting element  2217  and the extra fin  222  at corresponding locations, and the height of the supporting element  2217  is greater than the height of the extra fin  222 . Therefore, during installation, the supporting element  2217  is in contact with a ground or the like, and the extra fin  222  is not in contact with the ground, that is, there is a gap between the extra fin  222  and the ground. This facilitates air circulation, thereby improving heat dissipation efficiency. 
     The free end of the supporting element  2217  is inclined relative to a plane on which the extra substrate  221  is located. It can be understood that a range of an inclination angle is greater than or equal to 10° and less than 90°. When the inclination angle is less than 10°, the inclination angle is excessively small, and heat dissipation efficiency cannot be effectively improved. When the inclination angle is greater than or equal to 90°, it is equivalent to a case that the heat dissipation apparatus is vertically installed or reversely installed. 
     It can be understood that, when the heat dissipation apparatus  20  is horizontally installed (for example, when an installation carrier is a rooftop or a water surface, the heat dissipation apparatus  20  is usually located on the rooftop or the water surface, and the inverter  10  is located on a side of the heat dissipation apparatus facing away from the rooftop or the water surface), during natural heat dissipation of the heat dissipation apparatus  20 , hot air in the heat dissipation apparatus  20  is blocked by the inverter  10  in a process of rising, and cannot be effectively dissipated, but can only be dissipated through two side ends of a ventilation duct. As a result, a heat dissipation capability of the heat dissipation apparatus  20  is severely attenuated (the heat dissipation capability is attenuated by 20% to 30%). If thermal energy generated by the inverter  10  cannot be dissipated in a timely manner, performance of the inverter  10  is affected, leading to reduction of an electric energy yield of the inverter  10 . In this implementation, for example, when both the supporting element  2217  and the extra fin  222  are rectangular, that is, the free end (that is, the first free end  2219 ) of the supporting element  2217  is not disposed obliquely relative to the plane on which the extra substrate  221  is located, but the height of the supporting element  2217  is greater than the height of the extra fin  222 , the gap between the extra fin  222  and the ground helps improve heat dissipation efficiency. When the height of the supporting element  2217  is greater than the height of the extra fin  222 , and the free end (that is, the first free end  2219 ) of the supporting element  2217  is disposed obliquely relative to the plane on which the extra substrate  221  is located (it can be understood that a perpendicular projection of the supporting element  2217  in a direction perpendicular to the extra substrate  221  may be triangular or trapezoidal), both the gap between the extra fin  222  and the ground and the oblique disposition of the free end of the supporting element  2217  relative to the extra substrate  221  improve exchange efficiency of hot and cold air and weaken impact on the heat dissipation capability of the heat dissipation apparatus  20  that is caused by the inverter  10  blocking hot and cold air, thereby implementing effective heat dissipation when the heat dissipation apparatus  20  is horizontally installed. 
     The supporting element  2217  may be located at an edge of the extra substrate  221  (that is, the extra fin  222  is disposed on only one side of the supporting element  2217 ). Alternatively, the supporting element  2217  may be located at a non-edge location on the extra substrate  221 , in other words, the supporting element  2217  is located between two adjacent extra fins  222  (that is, the extra fins  222  are disposed on both sides of the supporting element  2217 ). 
     The supporting element  2217  and the extra substrate  221  may be an integral structure, which simplifies an installation process. A quantity of supporting elements  2217  is not limited. There may be two supporting elements  2217 . To stabilize a center of gravity during installation of the heat dissipation apparatus  20 , the two supporting elements  2217  may be symmetrically disposed. In another implementation, alternatively, the quantity of supporting elements  2217  may be 3, 4, or the like, to increase installation stability of the heat dissipation apparatus  20 . 
     It can be understood that, referring to  FIG.  13   , in a case of installation on a horizontal plane  115 , the supporting element  2217  is in contact with the horizontal plane  115 , and a channel  28  (that is, a gap between the extra fins  222  and the horizontal plane  115 ) is formed between the extra fins  222  and the horizontal plane  115 , thereby facilitating air exchange and heat dissipation. Each of the inverter  10 , the main heat sink  21 , and the extra heat sink  22  is at an inclination angle A 1  with the horizontal plane  115 . Hot air can be dissipated from two ends of the inclination. Compared with a case in which the extra fins  222  are horizontally disposed, disposing the extra fins  222  obliquely relative to the horizontal plane  115  by using the supporting element  2217  facilitates rise of hot air and improves the heat dissipation capability. Referring to  FIG.  14   , in a case of installation on an inclined plane  116 , the supporting element  2217  is in contact with the inclined plane  116 , an included angle between the inclined plane  116  and a horizontal plane is A 2 , and each of the inverter  10 , the main heat sink  21 , and the extra heat sink  22  is at an inclination angle of A 1 +A 2  with the horizontal plane. Hot air can be dissipated from two ends of the inclination. This facilitates rise of hot air, improves the heat dissipation capability, and reduces impact caused by the inverter  10  blocking exchange of hot and cold air. 
       FIG.  15   ,  FIG.  16   , and  FIG.  17    are respectively a diagram of an overall structure, a top view, and a sectional view of the heat dissipation apparatus according to a possible implementation. The extra heat sink  22  has a plurality of extra fins  222 . The plurality of extra fins  222  are disposed side by side on the extra substrate  221 . A surface, of each extra fin  222 , farther away from the extra substrate  221  is disposed obliquely relative to the extra substrate  221 , to improve heat dissipation efficiency. Specifically, in this implementation, surfaces, of all the extra fins  222 , father away from the extra substrate  221  are disposed obliquely relative to the extra substrate  221  (it can be understood that a perpendicular projection of the extra fin  222  in a direction perpendicular to the extra substrate  221  may be triangular or trapezoidal), so that exchange of hot and cold air can be increased, and there is a specific inclination angle between the extra fin  222  and a rooftop or a water surface. In this way, hot air can be effectively dissipated through the inclined fins, thereby improving exchange efficiency of hot and cold air, and weakening impact on the heat dissipation capability of the heat dissipation apparatus  20  that is caused by the inverter  10  blocking hot and cold air. In addition, because all the extra fins  222  in this implementation are obliquely disposed, a heat dissipation area is increased, thereby implementing effective heat dissipation when the heat dissipation apparatus  20  is horizontally installed. 
     An inclination angle A 1  is disposed between the extra substrate  221  and the surface, of each extra fin  222 , farther away from the extra substrate  221 . The inclination angle A 1  between the extra substrate  221  and the surface, of the extra fin  222 , farther away from the extra substrate  221  is greater than or equal to 10° and less than 90°. When the inclination angle A 1  between the extra substrate  221  and the surface, of the extra fin  222 , farther away from the extra substrate  221  is less than 10°, the inclination angle is excessively small, and heat dissipation efficiency cannot be effectively improved. When the inclination angle A 1  between the extra substrate  221  and the surface, of the extra fin  222 , farther away from the extra substrate  221  is greater than or equal to 90°, it is equivalent to a case that the heat dissipation apparatus  20  is vertically or reversely installed. 
     It can be understood that, referring to  FIG.  18   , in a case of installation on a horizontal plane  115 , the extra fins  222  are in contact with the horizontal plane  115 , and each of the inverter  10 , the main heat sink  21 , and the extra heat sink  22  is at an inclination angle A 1  with the horizontal plane  115 . Hot air can be dissipated from two ends of the inclination. This facilitates rise of hot air. Referring to  FIG.  19   , in a case of installation on an inclined plane  116 , the extra fins  222  are in contact with the inclined plane  116 , an included angle between the inclined plane  116  and a horizontal plane is A 2 , and each of the inverter  10 , the main heat sink  21 , and the extra heat sink  22  is at an inclination angle of A 1 +A 2  with the horizontal plane. Hot air can be dissipated from two sides. This facilitates rise of hot air and improves the heat dissipation capability. 
     Compared with the implementation in  FIG.  10    where only the supporting element  2217  is disposed obliquely relative to the extra substrate  221 , in this implementation, the surface, of each extra fin  222 , farther away from the extra substrate  221  is disposed obliquely relative to the extra substrate  221 , thereby increasing the heat dissipation area, and implementing effective heat dissipation when the heat dissipation apparatus  20  is horizontally installed. Correspondingly, a weight and costs of the heat dissipation apparatus  20  are also increased. Therefore, whether only the supporting element  2217  is disposed obliquely relative to the extra substrate  221  or the surface, of each extra fin  222 , farther away from the extra substrate  221  is disposed obliquely relative to the extra substrate  221  may be set based on a need. 
     In another implementation, alternatively, a surface, of only some of the extra fins  222 , farther away from the extra substrate  221  may be disposed obliquely relative to the extra substrate  221 . In other words, during installation, only some of the extra fins  222  are in contact with and fastened to an installation carrier such as the horizontal plane  115  or the inclined plane  116 . This may be flexibly performed based on a need. 
       FIG.  20   ,  FIG.  21   , and  FIG.  22    are respectively a diagram of an overall structure, a top view, and a sectional view of the heat dissipation apparatus according to a possible implementation. The heat dissipation apparatus  20  further includes an auxiliary heat sink  24 . The auxiliary heat sink  24  is connected to the extra heat sink  22 . The auxiliary heat sink  24  and the extra heat sink  22  together surround the main heat sink  21  partially. The auxiliary heat sink  24  is configured to assist the extra heat sink  22  in heat dissipation. Specifically, the main fin includes a first end part  2121 , a second end part  2122 , and a side part  2123  located between the first end part  2121  and the second end part  2122 . The first end part  2121  is connected to the main substrate  211 , and the auxiliary heat sink  24  is located at the side part  2123  of the main fin. The auxiliary heat sink  24  is disposed on the extra heat sink  22 , thereby adding a heat dissipation means, so that heat dissipation efficiency can be improved. There may be one auxiliary heat sink  24 , and the auxiliary heat sink  24  is located on one side of the extra heat sink  22 . Alternatively, there may be two auxiliary heat sinks  24 , and the two auxiliary heat sinks  24  are distributed opposite each other on two sides of the extra heat sink  22 . In this application, a quantity of auxiliary heat sinks  24  is not limited, and may be set based on a heat dissipation need. 
     The auxiliary heat sink  24  includes an auxiliary substrate  241  and an auxiliary fin  242 . A gap is disposed between the auxiliary substrate  241  and the main heat sink  21 , so as to facilitate air circulation, thereby improving heat dissipation efficiency. 
     It can be understood that the auxiliary substrate  241  may be provided with a cavity. A heat conducting structure such as a heat pipe or a vapor chamber is disposed in the cavity. In this way, part of thermal energy conducted to the extra heat sink  22  is dissipated through the extra fin  222 , and the rest of the thermal energy can be conducted to the auxiliary fin  242  through a heat conducting structure in the auxiliary substrate  241 , so as to be dissipated. This implements multi-means heat dissipation, thereby improving heat dissipation efficiency. 
     In a possible implementation, the auxiliary substrate  241  and the extra substrate  221  may be fixedly connected in a manner such as friction stir welding, and a split structure facilitates transportation; or the extra heat sink  22  and the auxiliary heat sink  24  are an integral structure, which simplifies an installation process. 
     When the heat dissipation apparatus is vertically installed in a direction shown in  FIG.  20   , extension directions of the main fin  212  and the extra fin  222  are parallel to a gravity direction. A ventilation duct is formed between adjacent main fins  212 , and a ventilation duct is formed between adjacent extra fins  222 . Extension directions of the ventilation ducts are parallel to the gravity direction. During natural heat dissipation, hot air  25  rises, and cold air  26  falls. As the extension directions of the main fin  212  and the extra fin  222  are parallel to the gravity direction (that is, an air circulation direction is parallel to the gravity direction), the hot air  25  is not blocked when passing through the ventilation duct between two fins during rising, and a heat dissipation effect is better. 
     Referring to  FIG.  23    and  FIG.  24   , when the heat dissipation apparatus is vertically installed in a direction shown in  FIG.  23    and  FIG.  24   , the auxiliary fin  242  may be a vertical fin, a horizontal fin, a fin inclined at any angle, a pin fin, or the like. The auxiliary heat sink  24  is on a side face of the inverter  10 , so that exchange of hot and cold air is not blocked by the inverter  10 . Therefore, a fin shape of the auxiliary heat sink  24  is not limited and may be various shapes, and fin shapes of two auxiliary heat sinks  24  may be different. 
     It can be understood that, alternatively, the extra heat sink  22  and the auxiliary heat sink  24  may be provided with no extra fin  222  and auxiliary fin  242 , and the extra heat sink  22  and the auxiliary heat sink  24  are configured as heat pipes or vapor chambers, to dissipate heat through a phase-change medium in the heat pipes or the vapor chambers. 
     In a possible implementation, the main heat sink  21 , the extra heat sink  22 , and the auxiliary heat sink  24  may be processed in manners such as die casting, extrusion, relieving, gear shaping, and bonding. 
     With the split heat dissipation apparatus  20  provided in this application, thermal energy generated by the inverter  10  can be conducted from the main heat sink  21  to the extra heat sink  22  through the heat conducting element  23 . The dual heat dissipation function of the main heat sink  21  and the extra heat sink  22  improves the heat dissipation capability of the heat dissipation apparatus  20 , and flexible configuration is implemented. In addition, because the extra heat sink  22  and the inverter  10  provided with the main heat sink  21  can be separately transported and be assembled on site, the overall weight and size of the inverter  10  are not increased, and a problem of difficult installation and maintenance is avoided. According to the design of the extra heat sink  22  in this application, when the extra heat sink  22  is installed horizontally or at a small angle on a rooftop and a water surface, an included angle between the heat dissipation apparatus  20  and the horizontal plane is increased, thereby improving the heat dissipation capability of the heat dissipation apparatus  20 . 
     The foregoing is merely some embodiments and implementations of this application, but is not intended to limit the protection scope of this application. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in this application shall fall within the protection scope of this application.