Capacitor

Abstract

To provide a capacitor that is improved in cooling performance and furthermore has assembly easiness.SOLUTION: A capacitor element and a cooling plate 7 are housed in an approximately rectangular parallelepiped-shaped capacitor case 3. The cooling plate 7 has a main body portion 7a that is housed within the capacitor case 3 together with the capacitor element, and a terminal portion 7b that is exposed from the capacitor case 3. Resin is infilled into the capacitor case 3, and the capacitor element and the cooling plate 7 are fixed while they are insulated from each other. A joint surface that is one surface of the rectangular parallelepiped-shaped capacitor case 3, is joined to a housing 5 of a power converter directly or via a heat transfer member 4. The main body portion 7a of the cooling plate 7 is arranged near a surface on the other side of the joint surface of the capacitor case 3. The terminal portion 7b of the cooling plate 7 and the housing 5 of the power converter are connected together.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a cooling technique for a capacitor provided in a power conversion device (such as an inverter unit).

Background Art

[0002] FIG. 7 shows an electrical circuit diagram of a general inverter unit. As shown in FIG. 7, a capacitor (for example, a film capacitor) C is connected between a P terminal and an N terminal. Also, switching elements Su, Sx, switching elements Sv, Sy, and switching elements Sw, Sz are connected in series between the P terminal and the N terminal. The switching elements are, for example, IGBTs, and the switching elements Su to Sz constitute an inverter (IGBT package) 1.

[0003] A motor M is connected to the AC side of the inverter 1 (connection points of the switching elements Su, Sx, connection points of the switching elements Sv, Sy, connection points of the switching elements Sw, Sz). Also, a current sensor 2 is provided between the inverter 1 and the motor M.

[0004] The capacitor C serves to smooth the DC link voltage. Also, a discharge resistor R is connected in parallel to the capacitor C. The discharge resistor R is provided to discharge the charge of the capacitor C when the input power supply of the inverter unit is turned off. This prevents electric shock accidents.

[0005] FIG. 8 shows the configuration of a conventional capacitor C. As shown in FIG. 8, the capacitor C is housed in a rectangular parallelepiped capacitor case 3.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

[0007] Capacitor C is a heat-generating component because it constantly carries current. In existing configurations, to cool capacitor C, a thermal conductive sheet 4 is placed on the top and bottom surfaces of capacitor C, and cooling is achieved by further bringing the capacitor C into contact with the inverter unit housing 5 via the thermal conductive sheet 4. Patent document 1 discloses prior art related to this technology.

[0008] However, the actual heat-generating part is inside the molded capacitor (capacitor element and internal conductor), and the generated heat is dissipated through the resin mold → capacitor case 3 → thermal conductive sheet 4 → inverter unit housing 5, so sufficient cooling performance cannot be obtained.

[0009] Furthermore, although capacitor C is a large component within the inverter unit, the heat generated by capacitor C became a bottleneck when attempting to miniaturize it.

[0010] Based on the above, the challenge is to provide a capacitor that combines improved cooling performance with ease of assembly. [Means for solving the problem]

[0011] The present invention was devised in view of the above-mentioned conventional problems, and one embodiment thereof is a capacitor provided in a power conversion device, comprising a capacitor element, a substantially rectangular parallelepiped capacitor case for housing the capacitor element, a main body portion housed together with the capacitor element in the capacitor case, a terminal portion exposed from the capacitor case, a cooling plate having a resin, and a resin filled in the capacitor case for fixing the capacitor element and the cooling plate in an insulated state, wherein one surface of the rectangular parallelepiped capacitor case, which is the joining surface, is joined to the housing of the power conversion device directly or via a heat transfer member, the main body portion of the cooling plate is positioned near the surface of the capacitor case opposite to the joining surface, and the terminal portion of the cooling plate is connected to the housing of the power conversion device.

[0012] Furthermore, in one embodiment, the four sides of the capacitor case opposite to the bonding surface are characterized in that the side exposing the terminal portion of the cooling plate and the side exposing the electrode terminals of the capacitor element are different.

[0013] Furthermore, in one embodiment, the cooling plate is characterized by being provided with studs for mounting the substrate.

[0014] Another embodiment is characterized by arranging a discharge resistor connected in parallel to the capacitor element on the cooling plate. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a capacitor that combines improved cooling performance with ease of assembly. [Brief explanation of the drawing]

[0016] [Figure 1] A perspective view showing the configuration of a conventional capacitor and the capacitor of Embodiment 1. [Figure 2] A diagram showing how to set the cooling plate in the capacitor of Embodiment 1. [Figure 3] A diagram showing the state where the capacitor of Embodiment 1 is installed in the housing of the inverter unit. [Figure 4] A diagram showing the cooling path of the capacitor of Embodiment 1. [Figure 5] A perspective view showing the configuration of the capacitor of Embodiment 2. [Figure 6] A perspective view showing the configuration of the capacitor of Embodiment 3. [Figure 7] An electrical circuit diagram of a general inverter unit. [Figure 8] A diagram showing the configuration of a conventional capacitor.

Mode for Carrying Out the Invention

[0017] Hereinafter, Embodiments 1 to 3 of the capacitor in the present invention will be described in detail based on FIGS. 1 to 6.

[0018] [Embodiment 1] In this Embodiment 1, a capacitor provided in a power conversion device will be described. FIG. 1(a) shows an existing capacitor, and FIG. 1(b) shows the capacitor of this Embodiment 1.

[0019] As shown in FIGS. 1(a) and 1(b), the capacitor element C is housed in a rectangular parallelepiped capacitor case 3. The electrode terminals 6 of the capacitor element are exposed from the capacitor case 3.

[0020] As shown in FIG. 1(b), the capacitor of this Embodiment 1 has a capacitor element C and a cooling plate 7 arranged inside the capacitor case 3 and integrally molded. The cooling plate 7 has a substantially flat plate shape and includes a main body portion 7a housed in the capacitor case 3 together with the capacitor element C and a terminal portion 7b exposed from the capacitor case 3.

[0021] As shown in FIGS. 1(b) and 2, with the capacitor element C and the cooling plate 7 arranged in the capacitor case 3, the resin is filled, and the electrode terminals (P terminal, N terminal) 6 of the capacitor element C and the cooling plate 7 are fixed in a state of being electrically insulated.

[0022] As shown in Figure 3, the capacitor case 3 is placed on the casing 5 of the inverter unit. A heat transfer member (e.g., a thermal conductive sheet, hereinafter referred to as a thermal conductive sheet) 4 is provided between the capacitor case 3 and the casing 5 of the inverter unit. The thermal conductive sheet 4 may be omitted. That is, one face of the rectangular capacitor case 3, which is the joining surface, is joined to the casing 5 of the inverter unit either directly or via the thermal conductive sheet 4, and the main body 7a of the cooling plate 7 is placed near the face opposite to the joining surface. In this specification, "near" the face opposite to the joining surface refers to the upper half of the capacitor case 3.

[0023] The inverter unit's housing 5 has four cylindrical sections 8 erected on it. Screw holes are formed in these cylindrical sections 8. The terminal section 7b of the cooling plate 7 and the cylindrical sections 8 of the housing 5 are fixed together with screws 9 or the like.

[0024] Furthermore, the side of the capacitor case 3 opposite to the joint surface (the opening surface) consists of four sides that form a rectangle. Of the four sides of the opening surface of the capacitor case 3, the terminal portion 7b of the cooling plate 7 is exposed from sides (two sides) that are different from the sides (two sides) on which the electrode terminals 6 of the capacitor C are exposed.

[0025] The following describes the capacitor cooling method based on Figure 4.

[0026] By placing the cooling plate 7, the heat generated inside the capacitor C (capacitor elements and internal conductors) is dissipated via the resin mold (short distance) → cooling plate 7 → inverter unit housing 5, as shown in Figure 4.

[0027] In the conventional configuration, the heat generated inside the capacitor is dissipated via the resin mold (at a distance) → capacitor case 3 → heat conductive sheet 4 → inverter unit housing 5.

[0028] Therefore, the cooling path is shorter than in the conventional configuration (by omitting the distance of the resin mold and the capacitor case 3), and heat can be efficiently discharged to the inverter unit housing 5 via a cooling plate 7 (made of a material with high thermal conductivity) which has high cooling capacity.

[0029] Furthermore, in Figure 3, the top surface of the capacitor case 3 is cooled by installing a cooling plate 7, and the bottom surface of the capacitor case 3 is cooled by connecting it to the inverter unit housing 5 via a thermal conductive sheet 4. In this way, by providing a cooling mechanism on each of the opposite sides of the capacitor C, the capacitor C can be cooled efficiently.

[0030] Furthermore, the terminal portion 7b of the cooling plate 7 and the electrode terminal 6 of the capacitor C are exposed from different sides of the opening surface of the capacitor case 3. This facilitates the design and installation of the mounting structure for the terminal portion 7b of the cooling plate 7 to the housing 5 of the inverter unit.

[0031] As described above, according to this embodiment 1, since the capacitor C and the cooling structure are integrated, there is no need to add an external heat dissipation mechanism such as a heat conductive sheet 4 when cooling the upper surface of the capacitor case 3.

[0032] During the assembly of the inverter unit, only the terminal portion 7b of the cooling plate 7 needs to be fixed, eliminating the need for the process of attaching thermal conductive sheets 4, etc., thus simplifying assembly.

[0033] By having a cooling mechanism (cooling plate 7) inside capacitor C, the inside can be actively cooled, improving the cooling capacity.

[0034] Therefore, it becomes possible to provide a capacitor that combines improved cooling capacity with ease of assembly.

[0035] [Embodiment 2] As shown in Figure 5(a), the capacitor of this second embodiment is configured in addition to the configuration of the first embodiment by providing studs 10 on the cooling plate 7, with a portion of the studs 10 exposed to the outside of the capacitor case 3. For example, as shown in Figure 5(a), four studs 10 are erected at the four corners of the cooling plate 7. Screw holes are provided in the studs 10.

[0036] Then, as shown in Figure 5(b), a control board 11, which controls the switching operation of switching elements (IGBTs, etc.) within the inverter unit, is screwed to the stud 10. Alternatively, components other than the control board 11 may be screwed to the stud 10.

[0037] This embodiment 2, with its configuration, achieves the same effects and advantages as embodiment 1.

[0038] Furthermore, it becomes possible to place components (control board 11) on top of capacitor C, enabling miniaturization.

[0039] Furthermore, the cooling plate 7 allows not only the heat generated by the capacitor C, but also the heat generated by the component (control board 11) located above the capacitor C, to be dissipated by the stud 10 and the cooling plate 7.

[0040] Furthermore, the cooling plate 7 can block the noise generated by capacitor C. This reduces noise-related malfunctions of the control board 11 and improves its noise immunity. [Embodiment 3] The capacitor of this third embodiment, as shown in Figure 6, has a configuration in addition to the configuration of the first embodiment, with a discharge resistor R attached to the cooling plate 7.

[0041] As shown in Figure 6, a discharge resistor R is placed on the cooling plate 7. This discharge resistor R is fixed together with the cooling plate 7 by resin filling.

[0042] This embodiment 3, with its configuration, achieves the same effects and advantages as embodiment 1.

[0043] Conventionally, the capacitor C and the discharge resistor R were separate components, each requiring its own cooling. As shown in Figure 6, this third embodiment integrates the capacitor C and the discharge resistor R into a single unit, allowing for the sharing of the cooling section and a unified cooling structure.

[0044] Furthermore, since the discharge resistor R is part of the capacitor C's components, the separate assembly of the discharge resistor R is unnecessary, reducing the number of steps and simplifying unit assembly.

[0045] Furthermore, the harness connecting the capacitor C and the discharge resistor R becomes unnecessary.

[0046] Although the present invention has been described in detail only with respect to the specific examples described above, it will be obvious to those skilled in the art that a wide variety of modifications and alterations are possible within the scope of the technical concept of the present invention, and it is natural that such modifications and alterations fall within the scope of the claims. [Explanation of Symbols]

[0047] C... Capacitor R…discharge resistance Su~Sz... Switching element 1…Inverse converter 2…Current sensor 3… Capacitor case 4…Heat conductive sheet (heat transfer component) 5. Enclosure of the inverter unit (power converter) 6...Electrode terminal 7…Cooling plate 7a...Body part 7b…Terminal section 8...Cylindrical section 9... screw 10...Stat 11…Control board

Claims

1. A capacitor installed in a power conversion device, Capacitor element and A capacitor case with a roughly rectangular parallelepiped shape for housing the aforementioned capacitor element, A main body portion housed together with the capacitor element in the capacitor case, a terminal portion exposed from the capacitor case, and a cooling plate, A resin that is filled inside the capacitor case and fixes the capacitor element and the cooling plate in an insulated state, Equipped with, One of the rectangular parallelepiped capacitor cases, which is the bonding surface, is bonded to the housing of the power converter either directly or via a heat transfer member. The main body of the cooling plate is positioned near the surface of the capacitor case opposite to the bonding surface. The terminal portion of the cooling plate and the housing of the power converter are connected, A capacitor characterized in that the cooling plate is provided with studs for mounting to a circuit board.

2. A capacitor installed in a power conversion device, Capacitor element and A capacitor case with a roughly rectangular parallelepiped shape for housing the aforementioned capacitor element, A main body portion housed together with the capacitor element in the capacitor case, a terminal portion exposed from the capacitor case, and a cooling plate, A resin that is filled inside the capacitor case and fixes the capacitor element and the cooling plate in an insulated state, Equipped with, One of the rectangular parallelepiped capacitor cases, which is the bonding surface, is bonded to the housing of the power converter either directly or via a heat transfer member. The main body of the cooling plate is positioned near the surface of the capacitor case opposite to the bonding surface. The terminal portion of the cooling plate and the housing of the power converter are connected, A capacitor characterized in that a discharge resistor connected in parallel to the capacitor element is placed on the cooling plate.

3. A capacitor installed in a power conversion device, Capacitor element and A capacitor case with a roughly rectangular parallelepiped shape for housing the aforementioned capacitor element, A main body portion housed together with the capacitor element in the capacitor case, a terminal portion exposed from the capacitor case, and a cooling plate, A resin that is filled inside the capacitor case and fixes the capacitor element and the cooling plate in an insulated state, Equipped with, One of the rectangular parallelepiped capacitor cases, which is the bonding surface, is bonded to the housing of the power converter either directly or via a heat transfer member. The main body of the cooling plate is positioned near the surface of the capacitor case opposite to the bonding surface. The terminal portion of the cooling plate and the housing of the power converter are connected, The terminal portion of the cooling plate is exposed toward the outside of the capacitor case from the vicinity of two opposing sides of the four sides of the side of the capacitor case opposite to the joining surface. The electrode terminals of the capacitor element are exposed toward the outside of the capacitor case from the vicinity of two opposing sides of the four sides of the side of the capacitor case opposite to the bonding surface. A capacitor characterized in that the side of the cooling plate that exposes the terminal portion and the side of the capacitor element that exposes the electrode terminal are different.

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