Electrical device

Abstract

The electrical device includes an electrical component, an electrical component support portion, and an outer frame, an internal space is formed between the electrical component support portion and the outer frame, the electrical component is disposed in the internal space, and a gas having a water vapor pressure of 0.60 kPa or less is sealed in the internal space. Consequently, in an electrical device in which an electrical component such as an electrolytic capacitor is disposed in a sealed space, it is possible to prevent condensation on the wall surface of the sealed space, and to prevent damage to the electrical component due to air pressure.

Description

Technical Field

[0001] The present invention relates to electrical equipment. Background Art

[0002] In order to realize a zero-carbon society, countries are strongly calling for restrictions on CO2 emissions and are actively promoting the electrification of power systems as an alternative to engines using fossil fuels.

[0003] In all engine-driven mobile products, the application of power electronics is being studied, and the output density is being required to be increased. Along with this, the power electronics are being pursued to be applicable to all climates around the world. In aircraft, environmental resistance that can cope with rapid changes in altitude is required. At the same time, there are demands for improved cooling performance, higher voltage, and lighter weight, and technology development is being promoted for these purposes.

[0004] Patent Document 1 discloses an air conditioner having an inverter device driving an electric compressor, in which an inert gas is filled into a housing accommodating a power element and a control circuit controlling the power element as a condensation prevention structure in the housing of the inverter device. Patent Document 1 describes that the inert gas is filled at a pressure slightly higher than atmospheric pressure at room temperature.

[0005] Patent document 2 discloses a power conversion device for aircraft, which includes a sealed frame including a gas inlet valve and a gas outlet valve, a power semiconductor module arranged in the internal space of the sealed frame, and a dry gas filling the internal space of the sealed frame. In addition, Patent document 2 discloses that the dry gas is injected from the ambient air pressure (e.g., atmospheric pressure) outside the sealed frame to set the internal space of the sealed frame to a set pressure.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2004-219031

[0009] Patent Document 2: Japanese Patent No. 6878712 Summary of the invention

[0010] Patent Documents 1 and 2 disclose methods of increasing the gas pressure in a container in which electric components are arranged to be higher than the atmospheric pressure. However, depending on the type of electric component, some electric components may be damaged when the gas pressure becomes high.

[0011] An object of the present disclosure is to prevent condensation from forming on a wall surface or the like of a closed space and to prevent damage to the electric components due to air pressure in an electric device in which electric components such as an electrolytic capacitor are arranged in a closed space.

[0012] The electrical device disclosed herein includes an electrical component, an electrical component support portion, and an outer frame. An internal space is formed between the electrical component support portion and the outer frame. The electrical component is disposed in the internal space. A gas having a water vapor pressure of 0.60 kPa or less is sealed in the internal space.

[0013] Effects of the Invention

[0014] According to the present disclosure, in an electrical device in which electrical components such as an electrolytic capacitor are arranged in a closed space, condensation can be prevented from occurring on a wall surface of the closed space, and damage to the electrical components due to air pressure can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a schematic cross-sectional view showing the electric device of Example 1.

[0016] Figure 2 1 is a schematic cross-sectional view showing an electric device according to a second embodiment.

[0017] Figure 3 1 is a schematic cross-sectional view showing an electric device according to a third embodiment.

[0018] Figure 4 1 is a schematic cross-sectional view showing an electric device according to a fourth embodiment.

[0019] Figure 5 1 is a schematic cross-sectional view showing an electric device according to a fifth embodiment. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0021] It should be noted that in this specification, electrical equipment and electronic equipment that function using electricity as an energy source are collectively referred to as “electrical equipment.” Electrical equipment also includes power conversion devices.

[0022] [Example 1]

[0023] Figure 1 1 is a schematic cross-sectional view showing the electric device of Example 1.

[0024] The electric device shown in the figure is a power conversion device having a liquid cooling mechanism. The power conversion device includes a switching element 1 , an electrolytic capacitor 60 , a substrate 2 , a substrate support 21 , a heat conducting member 22 , and an outer frame 90 .

[0025] The liquid flow path 8 is provided in the substrate support portion 21. The substrate 2 and the heat conducting member 22 are provided on the substrate support portion 21. The switching element 1 is arranged so as to be in contact with the heat conducting member 22. The electrolytic capacitor 60 is arranged on the substrate 2.

[0026] The outer frame 90 is fixed to the substrate support portion 21 in a manner covering the switching element 1, the electrolytic capacitor 60, the substrate 2 and the heat-conducting component 22. Thus, an internal space 92 is formed between the substrate support portion 21 and the outer frame 90. The internal space 92 is completely sealed to prevent air from entering and exiting from the outside. The switching element 1, the electrolytic capacitor 60, the substrate 2 and the heat-conducting component 22 are configured not to be in contact with the outer frame 90. A gas substantially free of water vapor, such as dry air, is enclosed in the internal space 92. Thus, condensation does not occur on the inner wall surface of the outer frame 90. It should be noted that the water vapor pressure of the gas enclosed in the internal space 92 is preferably 0.60 kPa or less, more preferably 0.080 kPa or less, and particularly preferably 0.0020 kPa or less. Here, the composition of the dry air is the same as that of normal air (containing nitrogen with a volume fraction of approximately 78% and oxygen with a volume fraction of approximately 21% as main components.).

[0027] The switch element 1 includes a MOSFET (metal oxide semiconductor field effect transistor) or a power module. The substrate support portion 21 is made of metal. It should be noted that in this specification, components that function when energized, such as the switch element 1, are collectively referred to as "electrical components". Electrical components include capacitors, printed circuit boards (PCBs), and the like.

[0028] The outer frame 90 is made of metal such as aluminum alloy or stainless steel, and has strength sufficient to serve as a cover for the switch element 1. The thickness of the outer frame 90 also depends on the material, but is preferably about 2 to 3 mm.

[0029] Furthermore, since the outer frame 90 is made of metal, even if lightning strikes, noise current is unlikely to be generated inside the power conversion device, and malfunction can be unlikely to occur.

[0030] It is preferred that the contact area between the substrate support portion 21 and the heat conducting component 22 and the contact area between the switch element 1 and the heat conducting component 22 are wide enough to fully remove the heat generated in the switch element 1. In addition, it is preferred that the liquid flow path 8 of the substrate support portion 21 is configured so that the heat can be fully removed from the heat conducting component 22 by the liquid flowing in the liquid flow path 8. Examples of the liquid flowing into the liquid flow path 8 include water, mineral oil, fluorocarbon cooling materials, vegetable oil, etc. It should be noted that in this specification, the cooling of the power conversion device and the like by the liquid flowing into the liquid flow path 8 is described, but the cooling mechanism of the electrical equipment disclosed in the present invention is not limited to this, and gases such as air, refrigerants with phase change, etc. may also be used. Specifically, it may be a structure using forced air cooling or a structure using a heat pipe.

[0031] The electrolytic capacitor 60 is a structure for smoothing or filtering in the power conversion device. As such a capacitor, ceramic capacitors, film capacitors, hybrid capacitors, etc. are applied. Capacitors other than the capacitors exemplified here can also be applied, and the type of capacitor is not limited.

[0032] In the case of the electrolytic capacitor 60, a valve may be provided in order to prevent damage caused by increased gas pressure. In this case, when the gas pressure in the sealed internal space 92 of the power conversion device increases due to a temperature increase caused by operation, etc., there is a concern that the operation of the valve of the electrolytic capacitor 60 may be hindered. Therefore, it is preferable to finely adjust the gas pressure of the internal space 92 to be lower than the atmospheric pressure in advance when the power conversion device is not powered on, in other words, when the power conversion device is not heated and the temperature is not increased. In other words, it is preferable to make the initial pressure of the internal space 92 slightly negative in advance when the power conversion device is not operated.

[0033] Even with respect to electrical components other than the electrolytic capacitor 60 , the internal space 92 can be set to a negative pressure to offset the pressure increase during operation, thereby preventing the electrical components from being damaged.

[0034] It is preferable that the substrate support portion 21 having the liquid flow path 8 is set to a ground potential. It is preferable that the substrate support portion 21 is formed of a metal such as an aluminum alloy, stainless steel, or a copper alloy.

[0035] In a low-pressure environment, the partial discharge inception voltage is significantly lower than that in an atmospheric pressure environment. Therefore, a solid or liquid having a partial discharge inception voltage approximately 10 times higher than that of air needs to be applied to the surface that is grounded to the surface to which the voltage is applied.

[0036] In the case where there is a concern about the initiation of partial discharge due to high voltage, high electric field stress, etc., it is preferred to cover the portion with high electric stress, such as the vicinity of the switching element 1, with a solid insulating material such as silicone. This makes it difficult to generate partial discharge under low pressure. As a solid insulating material, polyphenylene sulfide resin (PPS), epoxy resin, unsaturated polyester, etc. are preferred.

[0037] The gas sealed in the internal space 92 may be nitrogen, argon, carbon dioxide, nitrogen dioxide, etc., in addition to dry air. As a characteristic of the gas, it is preferable that it does not liquefy even at -70° C. Alternatively, these gases may be mixed and sealed.

[0038] In addition, as the gas sealed in the internal space 92, oxygen can also be added to the dry air, and a gas with an oxygen concentration higher than that of the atmosphere (the volume fraction of oxygen concentration is 21%) can be used. By increasing the oxygen concentration, the electron adhesion of the sealed gas becomes higher, it is easy to suppress discharge, and the insulation is improved. As a gas with a higher electron adhesion like this, in addition to oxygen, carbon dioxide, sulfur hexafluoride, carbon monoxide, etc. can also be used. In addition, in addition to the above-mentioned sulfur hexafluoride, halogen-containing gases, etc. can also be mixed. As halogen-containing gases containing fluorine, chlorine, iodine, etc., fluorinated gases such as BF3 and CF4, chlorinated gases, Freon gases, etc. are known.

[0039] In addition, the internal space 92 may be decompressed to a vacuum state. In this case, the higher the vacuum degree, the better, specifically, preferably 1 Pa or less, more preferably 0.1 Pa or less. By setting the internal space 92 to a vacuum state, the water vapor pressure is also reduced, so condensation can be prevented. In addition, corrosion caused by condensation, malfunction caused by lightning surge, etc. can be prevented.

[0040] [Example 2]

[0041] In this embodiment, only the configuration different from that of Embodiment 1 will be described.

[0042] Figure 2 1 is a schematic cross-sectional view showing an electric device according to a second embodiment.

[0043] In this figure, a low pressure chamber 100 is provided between the substrate support 21 and the outer frame 90 in addition to the internal space 92. The internal space 92 and the low pressure chamber 100 are separated by a partition plate 101. The partition plate 101 is provided with a ventilation filter 99.

[0044] The electrical components are arranged in the internal space 92. The low pressure chamber 100 has a lower air pressure than the internal space 92. With this configuration, when the air pressure of the internal space 92 becomes high due to the heat generated by the electrical components, the ventilation filter 99 opens, and the gas in the internal space 92 can flow out to the low pressure chamber 100. In this case, the air pressure of the internal space 92 can also be made higher than the atmospheric pressure (1 atm) in the initial state.

[0045] [Example 3]

[0046] In this embodiment, only the configuration different from that of Embodiment 1 will be described.

[0047] Figure 3 1 is a schematic cross-sectional view showing an electric device according to a third embodiment.

[0048] In this figure, the switch element 1 is electrically connected to the outside through a cable 111. The cable 111 covers the lead wire. The outlet of the cable 111 provided in the outer frame 90 is sealed with silicone FIPG 112 or the like to ensure the airtightness of the internal space 92. Here, FIPG is an abbreviation of Formed In Place Gasket.

[0049] [Example 4]

[0050] In this embodiment, only the configuration different from that of Embodiment 3 is described.

[0051] Figure 4 1 is a schematic cross-sectional view showing an electric device according to a fourth embodiment.

[0052] In this figure, the external is electrically connected via a bus bar 115 connected to the switching element 1. A cable may be used instead of the bus bar 115. The cable is a structure in which a conductive wire is covered.

[0053] The connection part of the bus bar 115 provided on the outer frame 90 is a BNC connector 116 (Bayonet Neill-Concelman connector). This ensures the airtightness of the internal space 92. In addition, the connection work can be facilitated.

[0054] [Example 5]

[0055] In this embodiment, only the configuration different from that of Embodiment 1 will be described.

[0056] Figure 5 1 is a schematic cross-sectional view showing an electric device according to a fifth embodiment.

[0057] In this figure, replace Figure 1 Instead of the outer frame 90 (made of metal), a frame is used in which the outer wall surface of the flame retardant resin frame 130 is covered with a metal coating 131. This frame is also called an "outer frame". The metal coating 131 is preferably made of aluminum, iron, nickel, etc. The metal coating 131 can also be provided on the inner wall surface of the flame retardant resin frame 130. With this structure, it is possible to prevent fire and noise inflow during lightning strikes. In addition, the electrical equipment can be made lighter.

[0058] The material of the flame retardant resin frame 130 is preferably a foamed resin such as polyurethane, polystyrene, polyethylene, polypropylene, silicone, etc. In addition, a vacuum insulation material with glass wool, silicon powder, etc. as a core material is also preferred. It should be noted that the material of the flame retardant resin frame 130 is not limited thereto.

[0059] It should be noted that a metal frame may be used instead of the flame-retardant resin frame 130 .

[0060] It should be noted that, in the above-mentioned embodiment, the electric device has the substrate 2, the substrate support portion 21 and the heat conducting member 22, but the electric device of the present disclosure does not necessarily have these members, and may also have a member for supporting an electric member instead of the substrate support portion 21. In addition, an internal space may be formed between the member and the outer frame 90. In this specification, the substrate support portion 21 and the member are collectively referred to as the "electrical member support portion".

[0061] It should be noted that the electrical device disclosed herein can also be applied to all mobile devices such as aircraft, transportation equipment, and construction machinery.

[0062] Hereinafter, preferred embodiments of the electric device of the present disclosure will be collectively described.

[0063] The electrical components include electrolytic capacitors.

[0064] The air pressure of the internal space is set to be lower than the atmospheric pressure.

[0065] The gas in the inner space is dry air, nitrogen, argon, carbon dioxide or nitrogen dioxide, or a mixture of any two or more thereof.

[0066] The inner space is in a vacuum state.

[0067] The outer frame includes one or more of polyurethane, polystyrene, polyethylene, polypropylene, and silicone, and is formed by covering these materials with a metal coating.

[0068] The outer frame includes a vacuum heat insulating material, and the vacuum heat insulating material includes one or more of glass wool and silica powder as a core material.

[0069] The oxygen concentration of the gas in the inner space is greater than 21% by volume.

[0070] The gas in the internal space includes one or more of carbon dioxide, sulfur hexafluoride, carbon monoxide and a halogen-containing gas.

[0071] A low-pressure chamber adjacent to the internal space is provided between the electric component support portion and the outer frame. The low-pressure chamber is set to a lower air pressure than the internal space. A ventilation filter is provided between the internal space and the low-pressure chamber.

[0072] The electrical components are electrically connected to the outside via cables, and the cable take-out port provided on the outer frame is sealed with silicone FIPG.

[0073] The electrical components are electrically connected to the outside via cables or bus bars, and a BNC connector is provided at a cable outlet provided on the outer frame or at a connection portion of the bus bar.

[0074] Description of Reference Numerals

[0075] 1: switch element, 2: substrate, 8: liquid flow path, 21: substrate support, 22: heat conduction component, 60: electrolytic capacitor, 90: outer frame, 92: internal space, 99: ventilation filter, 100: low-pressure chamber, 101: partition plate, 111: cable, 112: silicone FIPG, 115: bus bar, 116: BNC connector, 130: flame-retardant resin frame, 131: metal coating.

Claims

1. An electrical device, comprising: Electrical components; Electrical component support portion; as well as Outer frame, An internal space is formed between the electrical component support portion and the outer frame. The electrical components are arranged in the inner space, The internal space is filled with a gas having a water vapor pressure of 0.60 kPa or less.

2. The electrical device according to claim 1, wherein: The electrical component includes an electrolytic capacitor.

3. The electrical device according to claim 1, wherein: The air pressure of the internal space is set to be lower than the atmospheric pressure.

4. The electrical device according to claim 1, wherein: The gas is dry air, nitrogen, argon, carbon dioxide or nitrogen dioxide, or a mixture of any two or more of these gases.

5. The electrical device according to claim 1, wherein: The internal space is in a vacuum state.

6. The electrical device according to claim 1, wherein: The outer frame includes one or more of polyurethane, polystyrene, polyethylene, polypropylene and silicone, and is formed by covering these materials with a metal coating.

7. The electrical device according to claim 1, wherein: The outer frame includes a vacuum insulation material, and the vacuum insulation material includes one or more of glass wool and silicon powder as a core material.

8. The electrical device according to claim 1, wherein: The volume fraction of oxygen concentration in the gas is greater than 21%.

9. The electrical device according to claim 1, wherein: The gas includes one or more of carbon dioxide, sulfur hexafluoride, carbon monoxide and a halogen-containing gas.

10. The electrical device according to claim 1, wherein: A low-voltage chamber adjacent to the internal space is provided between the electrical component support portion and the outer frame. The low pressure chamber is set to a lower pressure than the internal space. A ventilation filter is provided between the internal space and the low pressure chamber.

11. The electrical device according to claim 1, wherein: The electrical components are electrically connected to the outside via cables, The cable take-out port provided on the outer frame is sealed with silicone FIPG.

12. The electrical device according to claim 1, wherein: The electrical components are electrically connected to the outside via cables or bus bars. A BNC connector is provided at the cable outlet or the bus bar connection portion provided at the outer frame.

13. The electrical device according to claim 1, wherein: The electrical device is a power conversion device.

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