JP2024041340A - capacitor - Google Patents

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

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

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 the P terminal and the N terminal. Further, 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 inverse converter (IGBT package) 1.

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

Capacitor C serves to smooth the DC link voltage. Further, 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 to the inverter unit is turned off. This prevents electric shock accidents.

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.

JP2013-169070A JP 2021-197838 Publication

Capacitor C becomes a heat-generating component because current always flows through it. In order to cool the capacitor C, in the existing configuration, a thermally conductive sheet 4 is placed on the top and bottom surfaces of the capacitor C, and cooling is achieved by placing the thermally conductive sheet 4 in contact with the casing 5 of the inverter unit via the thermally conductive sheet 4. Was. Patent Document 1 is disclosed as a prior art document regarding this technology.

However, the actual heat generating part is inside the molded capacitor (capacitor element and internal conductor), and the generated heat is radiated through the resin mold → capacitor case 3 → heat conductive sheet 4 → inverter unit housing 5. Because of this, sufficient cooling performance cannot be obtained.

Furthermore, although the capacitor C is a large component within the inverter unit, the heat generated by the capacitor C has become a bottleneck when trying to downsize the inverter unit.

In view of the above, it is an issue to provide a capacitor that has improved cooling performance and is easy to assemble.

The present invention has been devised in view of the above-mentioned conventional problems, and one aspect thereof is a capacitor provided in a power conversion device, which includes a capacitor element and a substantially rectangular parallelepiped-shaped capacitor housing the capacitor element. A case, a main body part housed in the capacitor case together with the capacitor element, a terminal part exposed from the capacitor case, a cooling plate filled in the capacitor case, and containing the capacitor element and the cooling plate. a resin to be fixed in an insulated state, and a bonding surface, which is one surface of the rectangular parallelepiped capacitor case, is bonded to the casing of the power conversion device directly or through a heat transfer member, and the capacitor case The main body portion of the cooling plate is disposed near a surface opposite to the joint surface, and the terminal portion of the cooling plate and the casing of the power conversion device are connected.

Further, as one aspect thereof, in four sides of the surface of the capacitor case opposite to the bonding surface, a side exposing the terminal portion of the cooling plate and a side exposing the electrode terminal of the capacitor element are different. It is characterized by the presence of

Further, as one aspect thereof, the cooling plate is provided with studs for mounting a board.

Moreover, as another aspect, a discharge resistor connected in parallel to the capacitor element is arranged on the cooling plate.

According to the present invention, it is possible to provide a capacitor that has improved cooling performance and is easy to assemble.

FIG. 3 is a perspective view showing the configurations of a conventional capacitor and a capacitor of Embodiment 1. 6 is a diagram showing a method of setting a cooling plate in the condenser of Embodiment 1. FIG. FIG. 3 is a diagram showing a state in which the capacitor of Embodiment 1 is installed in the casing of an inverter unit. FIG. 3 is a diagram showing a cooling path of a capacitor according to the first embodiment. FIG. 3 is a perspective view showing the configuration of a capacitor according to a second embodiment. FIG. 3 is a perspective view showing the configuration of a capacitor according to a third embodiment. Electrical circuit diagram of a typical inverter unit. FIG. 1 is a diagram showing the configuration of a conventional capacitor.

Embodiments 1 to 3 of the capacitor according to the present invention will be described in detail below based on FIGS. 1 to 6.

[Embodiment 1]
In the first embodiment, a capacitor provided in a power conversion device will be described. FIG. 1(a) shows an existing capacitor, and FIG. 1(b) shows a capacitor according to the first embodiment.

As shown in FIGS. 1(a) and 1(b), the capacitor element C is housed in a capacitor case 3 having a rectangular parallelepiped shape. Electrode terminals 6 of the capacitor element are exposed from the capacitor case 3.

In the capacitor of the first embodiment, as shown in FIG. 1(b), a capacitor element C and a cooling plate 7 are arranged inside a capacitor case 3 and are integrally molded. The cooling plate 7 has a substantially flat plate shape and includes a main body portion 7 a housed in the capacitor case 3 together with the capacitor element C, and a terminal portion 7 b exposed from the capacitor case 3 .

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

As shown in FIG. 3, a capacitor case 3 is placed on the casing 5 of the inverter unit. A heat transfer member (for example, a heat conductive sheet, hereinafter referred to as a heat conductive sheet) 4 is provided between the capacitor case 3 and the casing 5 of the inverter unit. The heat conductive sheet 4 may be omitted. That is, the joint surface, which is one surface of the rectangular parallelepiped-shaped capacitor case 3, is joined to the inverter unit housing 5 directly or via the heat conductive sheet 4, and the cooling plate 7 is placed near the surface opposite to the joint surface. The main body portion 7a is arranged. In this specification, "near" the surface opposite to the joint surface refers to the upper half of the capacitor case 3.

The casing 5 of the inverter unit has four cylindrical sections 8 standing upright. This cylindrical portion 8 has a screw hole formed therein. The terminal portion 7b of the cooling plate 7 and the cylindrical portion 8 of the housing 5 are fixed with screws 9 or the like.

Further, the surface (opening surface) of the capacitor case 3 opposite to the joint surface is composed of four sides forming a quadrilateral. Among the four sides of the opening surface of the capacitor case 3, the terminal portion 7b of the cooling plate 7 is exposed from a different side (two sides) from the side (two sides) where the electrode terminal 6 of the capacitor C is exposed. .

Hereinafter, a method for cooling the capacitor will be explained based on FIG. 4.

By arranging the cooling plate 7, the heat generated inside the capacitor C (capacitor element and internal conductor) can be transferred from the resin mold (near distance) to the cooling plate 7 to the inverter unit housing 5, as shown in FIG. dissipate heat through.

In the conventional configuration, heat generated inside the capacitor is radiated via the resin mold (long distance) → capacitor case 3 → heat conductive sheet 4 → inverter unit casing 5.

Therefore, the cooling path is shorter than the conventional configuration (resin mold distance and capacitor case 3 are omitted), and the inverter unit housing is efficiently connected via the cooling plate 7 (made of a material with high thermal conductivity) with high cooling capacity. Heat can be discharged to the body 5.

In addition, in FIG. 3, the top side of the capacitor case 3 is cooled by installing a cooling plate 7, and the bottom side of the capacitor case 3 is cooled by being connected to the casing 5 of the inverter unit via a heat conductive sheet 4. are doing. In this way, by providing a cooling mechanism on each of the opposite surfaces of the capacitor C, the capacitor C can be efficiently cooled.

Further, 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 attachment work of the attachment structure of the terminal portion 7b of the cooling plate 7 to the casing 5 of the inverter unit.

As described above, according to the first embodiment, since the capacitor C and the cooling structure are integrated, it is necessary to add a heat dissipation mechanism such as a heat conductive sheet 4 to the outside when cooling the upper surface side of the capacitor case 3. There is no.

When assembling the inverter unit, only the terminal portions 7b of the cooling plate 7 are fixed, and the process of pasting the heat conductive sheet 4 and the like can be omitted, which facilitates assembly.

By having a cooling mechanism (cooling plate 7) inside the condenser C, the inside can be actively cooled, and the cooling capacity is improved.

Therefore, it is possible to provide a capacitor that has improved cooling capacity and is easy to assemble.

[Embodiment 2]
As shown in FIG. 5(a), the capacitor of the second embodiment has, in addition to the configuration of the first embodiment, a stud 10 provided on the cooling plate 7, with a part of the stud 10 exposed outside the capacitor case 3. For example, as shown in FIG. 5(a), four studs 10 are set up at the four corners of the cooling plate 7. The stud 10 is provided with a screw hole.

Then, as shown in FIG. 5(b), for example, a control board 11 that controls the switching operation of switching elements (IGBTs, etc.) in the inverter unit is screwed to the stud 10. Note that components other than the control board 11 may also be screwed to the stud 10.

With this configuration, the second embodiment provides the same effects as the first embodiment.

Moreover, it becomes possible to arrange components (control board 11) above the capacitor C, and it becomes possible to achieve miniaturization.

Further, the cooling plate 7 allows heat generated not only from the capacitor C but also from the components (control board 11) disposed above the capacitor C to be exhausted by the stat 10 and the cooling plate 7.

Further, the noise generated by the capacitor C can be blocked by the cooling plate 7. This makes it possible to reduce noise malfunctions of the control board 11 and improve noise resistance.
[Embodiment 3]
The capacitor of the third embodiment has a configuration in which a discharge resistor R is attached to the cooling plate 7 in addition to the configuration of the first embodiment, as shown in FIG.

As shown in FIG. 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 filling with resin.

With this configuration, the third embodiment provides the same effects as the first embodiment.

Conventionally, the capacitor C and the discharge resistor R were constructed as separate bodies, and each required cooling. As shown in FIG. 6, in the third embodiment, by integrating the capacitor C and the discharge resistor R, the cooling section can be shared, and the cooling structure can be unified.

Further, since the discharge resistor R becomes a part of the component of the capacitor C, there is no need to separately assemble the discharge resistor R, the number of steps can be reduced, and unit assembly becomes easy.

Furthermore, a harness connecting the capacitor C and the discharge resistor R is not required.

Although only the specific examples described in the present invention have been described in detail above, it is obvious to those skilled in the art that various modifications and modifications can be made within the scope of the technical idea of the present invention. Naturally, such variations and modifications fall within the scope of the claims.

C...Capacitor R...Discharge resistance Su~Sz...Switching element 1...Inverse converter 2...Current sensor 3...Capacitor case 4...Thermal conductive sheet (heat transfer member)
5... Housing of inverter unit (power converter) 6... Electrode terminal 7... Cooling plate 7a... Main body part 7b... Terminal part 8... Cylindrical part 9... Screw 10... Stat 11... Control board

Claims (4)

A capacitor provided in a power conversion device,
a capacitor element,
a substantially rectangular parallelepiped-shaped capacitor case that houses the capacitor element;
a cooling plate having a main body part housed in the capacitor case together with the capacitor element, a terminal part exposed from the capacitor case;
a resin filled in the capacitor case and fixing the capacitor element and the cooling plate in an insulated state;
Equipped with
A joint surface, which is one surface of the rectangular parallelepiped capacitor case, is joined to the casing of the power conversion device directly or via a heat transfer member,
arranging the main body of the cooling plate near a surface opposite to the joint surface of the capacitor case;
A capacitor, wherein the terminal portion of the cooling plate and the casing of the power conversion device are connected. On the four sides of the surface opposite to the joint surface of the capacitor case,
2. The capacitor according to claim 1, wherein a side of the cooling plate where the terminal portion is exposed is different from a side where the electrode terminal of the capacitor element is exposed. 2. The capacitor according to claim 1, wherein the cooling plate is provided with studs for mounting a board. 2. The capacitor according to claim 1, wherein a discharge resistor connected in parallel to the capacitor element is arranged on the cooling plate.

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