Electric power conversion equipment

Abstract

To improve the cooling efficiency of a capacitor in electric power conversion equipment.SOLUTION: In electric power conversion equipment comprising a smoothing capacitor C, the capacitor C comprises: ; capacitor element 11; a metallic capacitor case 14 housing the capacitor element 11; a plastic film; and resin 15. A sheet metal forming the capacitor case 14 is a metal-resin composite sheet metal with a plastic film attached to the inner surface side of the capacitor case 14. The resin 15 is filled into the inside of the capacitor case 14.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a capacitor configuration in a power conversion device. [Background technology]

[0002] FIG. 1 shows a circuit configuration of an inverter unit as an example of a general power conversion device, and FIG. 2 shows the configuration of a conventional inverter unit.

[0003] In the inverter unit 10, the capacitor C, which serves to smooth the DC link voltage, is a heat-generating component because a current always flows through the capacitor C. Therefore, the capacitor C needs to be cooled.

[0004] 2 shows an example of a structure for cooling the power semiconductor (IGBT package) 1 and the capacitor C in the inverter unit 10 by water cooling. There are also other structures for cooling heat-generating components by attaching them to self-cooling fins or air-cooling fins. Patent Document 1 is disclosed as a prior art for these structures.

[0005] In the existing configuration, as shown in FIG. 2, cooling was achieved by placing a thermally conductive sheet 3 on the bottom surface (or, in some cases, the top surface) of the capacitor C so that it was in contact with the housing 4 of the inverter unit 10.

[0006] Meanwhile, Patent Document 2 is disclosed as a prior art in which an aluminum resin composite panel is used for a capacitor for a weight sensor. However, Patent Document 2 does not state that a current of a predetermined amount or more flows through the capacitor for a weight sensor, generating heat, or that the configuration of Patent Document 2 has a cooling effect. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2021-197838 [Patent Document 2] JP 2011-22120 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, the actual heat generating part of the capacitor C is inside the molded capacitor C (the capacitor element and the internal conductor). The heat generated inside the capacitor C is dissipated via the resin mold → the case of the capacitor C → the thermally conductive sheet 3 → the housing 4 of the inverter unit 10 → the flow path 5, so sufficient cooling performance cannot be obtained.

[0009] Downsizing and heat generation of each item are issues in achieving a compact inverter unit 10 (high output density). Capacitor C is a large component even within inverter unit 10 (often the largest in volume among the electrical components shown in the electrical circuit of FIG. 1), and so heat generation from this capacitor C has been a bottleneck.

[0010] In view of the above, it is necessary to improve the cooling efficiency of the capacitor in the power conversion device. [Means for solving the problem]

[0011] The present invention was devised in consideration of the above-mentioned problems in the conventional art, and one aspect of the present invention is a power conversion device equipped with a smoothing capacitor, the capacitor comprising a capacitor element, a metal capacitor case that houses the capacitor element, and resin that is filled inside the capacitor case, and the sheet metal that forms the capacitor case is a metal-resin composite sheet metal having a plastic film attached to the inner surface side of the capacitor case.

[0012] In one aspect of the present invention, the capacitor is fixed to a housing of the power conversion device or to a heat sink attached to the housing of the power conversion device by a thermally conductive adhesive.

[0013] In one aspect, the power converter is characterized in that a flow path through which a coolant flows is formed in the housing of the power converter or in the heat sink.

[0014] In one embodiment, the capacitor case is made of aluminum. Effect of the Invention

[0015] According to the present invention, it is possible to improve the cooling efficiency of a capacitor in a power conversion device. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing a circuit configuration of a general power conversion device. [Diagram 2] FIG. 1 is a cross-sectional view showing the configuration of a conventional power conversion device. [Diagram 3] FIG. 2 is a perspective view showing a capacitor according to the embodiment. [Figure 4] FIG. 2 is a perspective view showing a housing of a capacitor and a power conversion device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of a power conversion device according to the present invention will be described in detail with reference to Figs.

[0018] [Embodiment] First, a typical power conversion device (for example, an inverter unit, hereinafter referred to as the inverter unit) will be described based on the electric circuit diagram in Fig. 1. As shown in Fig. 1, a capacitor (for example, a film capacitor) C is connected between a P terminal and an N terminal. In addition, 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 a power semiconductor (IGBT package) 1.

[0019] A motor M is connected to the AC side (the connection point of the switching elements Su and Sx, the connection point of the switching elements Sv and Sy, and the connection point of the switching elements Sw and Sz) of the power semiconductor 1. In addition, a current sensor 2 is provided between the power semiconductor 1 and the motor M.

[0020] Capacitor C serves to smooth the DC link voltage. A discharge resistor R is connected in parallel to capacitor C. Discharge resistor R is provided to discharge the charge in capacitor C when the input power of inverter unit 10 is turned off. This prevents electric shock accidents.

[0021] Capacitor C in this embodiment is shown in Fig. 3. The left side of Fig. 3 is an exploded perspective view of capacitor C, and the right side of Fig. 3 is a perspective view of capacitor C after assembly.

[0022] Capacitor C includes capacitor element 11, P-side conductor 12, N-side conductor 13, and capacitor case 14. Capacitor element 11 is housed in capacitor case 14 with P-side conductor 12 and N-side conductor 13 connected to each other. Then, capacitor case 14 is filled with resin 15.

[0023] The material of the capacitor case 14 is generally a resin material such as PPS (Polyphenylenesulfide), but to improve cooling performance, aluminum or other metals with high thermal conductivity are used.

[0024] However, since the potting (filling) resin 15 and the metal of the capacitor case 14 are incompatible, there is a high possibility that the resin 15 will peel off from the capacitor case 14 due to expansion and contraction.

[0025] Therefore, a metal-resin composite sheet metal is used, in which a plastic film (not shown) is attached to the sheet metal used to form capacitor case 14, and the capacitor case is manufactured so that the inner side of capacitor case 14 faces the plastic film. Since there is good compatibility between metal capacitor case 14 and the plastic film, and between filled resin 15 and the plastic film, the risk of resin 5 peeling off from capacitor case 14 is reduced.

[0026] 4 is a perspective view showing the capacitor C and the housing 4 of the inverter unit 10 in this embodiment. Note that in this embodiment, it is assumed that a flow path through which a refrigerant (for example, water) flows is formed in the housing 4 of the inverter unit 10.

[0027] Conventionally, a thermally conductive sheet was attached to the bottom surface of the capacitor case 14, and the capacitor C was placed so that it was in contact with the housing 4 of the inverter unit 10 via the thermally conductive sheet, thereby dissipating heat to the housing 4 of the inverter unit 10 only from the bottom surface of the capacitor case 14.

[0028] In this embodiment, the capacitor case 14 is fixed to the housing 4 of the inverter unit 10 with a thermally conductive adhesive. The capacitor case 14 contacts the housing 4 of the inverter unit 10 not only on its bottom surface but also on its sides. The portion of the housing 4 of the inverter unit 10 from the bottom to the dotted line contacts the side of the capacitor case 14. The thermally conductive adhesive is applied to the bottom and side of the capacitor case 14 and then the capacitor case 14 is fixed to the housing 4 of the inverter unit 10. As a result, it becomes possible to dissipate heat to the housing 4 of the inverter unit 10 not only from the bottom surface of the capacitor case 14 but also from the side surfaces.

[0029] [Explanation of Action and Operation] Aluminum or other metals are used as the material for the capacitor case 14. By using a metal with high thermal conductivity for the capacitor case 14, it is expected that the heat dissipation performance from the capacitor C to the housing 4 of the inverter unit 10 can be improved.

[0030] In addition, since the metal of capacitor case 14 and the filled resin 15 are incompatible, there is a possibility that resin 15 will peel off from capacitor case 14. Therefore, a metal-resin composite sheet metal is used in which a plastic film is attached to the metal sheet metal of capacitor case 14, and the capacitor case is manufactured so that the inner side is the plastic film side. Since the metal capacitor case 14 and the plastic film, and the resin 15 and the plastic film, are compatible with each other, it is possible to prevent the resin 15 from peeling off from capacitor case 14.

[0031] Furthermore, conventionally, a thermally conductive sheet was attached to the bottom surface of capacitor case 14 and the capacitor case was installed in housing 4 of inverter unit 10, thereby dissipating heat to the housing 4 of inverter unit 10 only from the bottom surface of capacitor case 14. In this embodiment, by using a thermally conductive adhesive, rather than a thermally conductive sheet, on the bottom and side surfaces of capacitor case 14 and installing it in housing 4 of inverter unit 10, it becomes possible to dissipate heat not only from the bottom surface of capacitor case 14 but also from the side surfaces.

[0032] [effect] According to this embodiment, it is possible to improve the cooling capacity of the capacitor C by using a metal with high thermal conductivity as the material for the capacitor case 14 and by using a thermally conductive adhesive to dissipate heat from the bottom and sides of the capacitor case 14 to the housing 4 of the inverter unit 10.

[0033] Furthermore, by using a metal-resin composite sheet metal with a plastic film attached to the sheet metal for the capacitor case 14 and fabricating the capacitor case so that the inner surface side faces the plastic film, it is possible to prevent the resin 15 from peeling off from the capacitor case 14. This reduces defects in the capacitor C and improves the reliability of the power conversion device.

[0034] Furthermore, the improved cooling capacity of capacitor C relaxes the ESR (Equivalent Series Resistance) conditions of capacitor C. In other words, since the ESR of capacitor C can be made larger than before, it becomes possible to reduce the thickness of the capacitor film. Furthermore, the improved cooling capacity of capacitor C makes it possible to increase the allowable current value per capacitance. As a result, it becomes possible to miniaturize capacitor C.

[0035] Furthermore, while conventionally the housing 4 of the inverter unit 10 and the capacitor case 14 are fixed with bolts or the like, in this embodiment the capacitor case 14 is fixed to the housing 4 of the inverter unit 10 with a thermally conductive adhesive, which makes it possible to reduce the number of bolts and the number of parts.

[0036] Although the present invention has been described in detail above only with respect to the specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the technical concept of the present invention, and it is natural that such modifications and variations fall within the scope of the claims.

[0037] For example, in the present embodiment, the capacitor C (capacitor case 14) is installed in the housing 4 of the inverter unit 10, but the capacitor C (capacitor case 14) may be installed in a water-cooled heat sink or an air-cooled heat sink that is separately attached to the housing 4 of the inverter unit 10. In the case of a water-cooled heat sink, a flow path is formed in the heat sink through which a refrigerant (water) flows.

[0038] Furthermore, in the embodiment, the inverter unit 10 provided with a smoothing capacitor has been described, but the present invention is also applicable to power conversion devices other than inverter units (for example, converters, choppers, etc.). [Explanation of symbols]

[0039] C: Capacitor R…discharge resistance Su~Sz...Switching elements M: Motor 1...Power semiconductor (IGBT module) 2...Current sensor 3…Heat conductive sheet 4…Inverter unit housing 5...Flow path 10...Power conversion device (inverter unit) 11...Capacitor element 12...P side conductor 13...N-side conductor 14…Capacitor case 15…Resin

Claims

1. A power conversion device equipped with a smoothing capacitor, The capacitor is A capacitor element; a metal capacitor case that houses the capacitor element; A resin is filled inside the capacitor case, A power conversion device, characterized in that the sheet metal used to form the capacitor case is a metal-resin composite sheet metal having a plastic film attached to the inner surface side of the capacitor case.

2. 2. The power conversion device according to claim 1, wherein the capacitor is fixed to a housing of the power conversion device or to a heat sink attached to the housing of the power conversion device by a thermally conductive adhesive.

3. 3. The power converter according to claim 2, wherein a flow path through which a coolant flows is formed in the housing of the power converter or in the heat sink.

4. 2. The power conversion device according to claim 1, wherein the capacitor case is made of aluminum.

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