Capacitor unit

Abstract

To provide a capacitor unit achieving both enhancement of heat dissipation and reduction of inductance.SOLUTION: Capacitor units 10 and 11 include first terminals 16a and 16b and second terminals 17, the first terminals being connected to a DC power supply side and the second terminals being connected to a ground potential side, and comprise first capacitor elements Cy-p1 and Cy-n1 and second capacitor elements Cy-p2 and Cy-n2. The first capacitor elements are provided with the first terminals, and the second capacitor elements are provided with the second terminals. The first terminals and the second terminals are electrically connected in series. Between the first capacitor elements and the second capacitor elements, a thermal conductive member 13 for thermally connecting the first capacitor elements and the second capacitor elements is provided. The first terminals and the second terminals are arranged in parallel with each other when viewed in an elevation direction.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a capacitor unit.

Background Art

[0002] In recent years, the electrification of automobiles has accelerated. Due to the increased output and large current of the inverter, the power loss (heat generation) of the DC bus bar has increased, and noise is generated due to the high frequency of the switching frequency. To suppress this, it is essential to add a filter circuit to the inverter. As a configuration example of a capacitor element unit used in the filter circuit, for example, in Patent Document 1 below, capacitor element units are connected by a bridging unit so as to form a Δ connection, and the separation distance between adjacent capacitor element units is arranged to be short.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A capacitor element unit having the role of a filter circuit needs to be configured near the DC bus bar. However, there is a problem that the heat-resistant temperature of the capacitor element unit exceeds due to the influence of the heat generation of the DC bus bar. At the same time, it is also necessary to improve the EMC noise suppression function of the filter circuit. Therefore, based on the configuration of Patent Document 1, it is an object to provide a capacitor unit having a configuration that achieves both improved heat dissipation and reduced inductance.

Means for Solving the Problems

[0005] A capacitor unit having a first terminal and a second terminal, wherein the first terminal is connected to a DC power supply side and the second terminal is connected to a ground potential side, the capacitor unit comprising a first capacitor element and a second capacitor element, the first capacitor element comprising the first terminal, the second capacitor element comprising the second terminal, the first terminal and the second terminal being electrically connected in series, and a heat conducting member for thermally connecting the first capacitor element and the second capacitor element being provided between the first capacitor element and the second capacitor element, and the first terminal and the second terminal being arranged parallel to each other as viewed in the elevation direction.

Advantages of the Invention

[0006] The present invention can provide a capacitor unit that achieves both improved heat dissipation and reduced inductance.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and for the sake of clarity of explanation, appropriate omissions and simplifications have been made. The present invention can also be implemented in various other forms. Unless otherwise limited, each component may be singular or plural.

[0009] The positions, sizes, shapes, ranges, etc. of the respective components shown in the drawings may not represent the actual positions, sizes, shapes, ranges, etc. in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0010] (One Embodiment and Overall Configuration) (Fig. 1) A power conversion device 1, an electric drive motor 2, and a high-voltage battery 3 (hereinafter referred to as battery 3) mounted on a vehicle are electrically connected to each other. The battery 3 is a DC power source in the power conversion device 1 and is electrically connected to the power conversion device 1 via a bus bar or a high-voltage cable. The DC power input from the battery 3 to the power conversion device 1 is converted into AC power by the power conversion device 1 and input to the electric drive motor 2. The electric drive motor 2 converts the input AC power into mechanical output. In this way, the electric drive motor 2 serves as a driving power source for an HEV (Hybrid Electric Vehicle) or an EV (Electric Vehicle). Also, the electric drive motor 2 regenerates power to the battery 3 from the AC power generated when an external force is applied via the wheels.

[0011] The power conversion device 1 includes a power conversion circuit section 4, a smoothing capacitor 7, and a noise filter circuit 8. The DC bus bar 5 electrically connects the battery 3 and the power conversion circuit section 4 and transmits the DC power output from the battery 3 to the power conversion circuit section 4. The DC bus bar 5 has a positive DC bus bar 5a and a negative DC bus bar 5b.

[0012] The power conversion circuit section 4 is composed of a plurality of power semiconductor elements and diode elements capable of converting the DC power generated from the battery 3 into AC power. The power conversion circuit section 4 is electrically connected to the electric drive motor 2 via a bus bar or a high-voltage cable. The diode elements in the power conversion circuit section 4 have a rectifying function of converting AC power into DC power during power regeneration. Note that the illustration of the drive circuit and the control circuit for driving the power conversion circuit section 4 is omitted.

[0013] The power conversion device 1 has a DC input terminal 6. The DC input terminal 6 is a connection terminal portion for electrically connecting the battery 3 and the DC bus bar 5. The smoothing capacitor 7 is electrically connected between the positive DC bus bar 5a and the negative DC bus bar 5b in the power conversion device 1, in front of the power conversion circuit portion 4. The smoothing capacitor 7 stabilizes the DC voltage input from the battery 3 and supplies power to the power conversion circuit portion 4.

[0014] The noise filter circuit 8 is electrically connected between the positive DC bus bar 5a and the negative DC bus bar 5b in the power conversion device 1, in front of the smoothing capacitor 7. The noise filter circuit 8 has an X capacitor group 9 that removes normal mode noise, and a first capacitor unit 10 and a second capacitor unit 11 that are Y capacitor units that remove common mode noise.

[0015] The first capacitor unit 10 and the second capacitor unit 11 are electrically connected in series at a series connection point 12. The first capacitor unit 10 and the second capacitor unit 11 are each electrically connected to the case ground via the series connection point 12. A connection point 12a paired with the series connection point 12 via the first capacitor unit 10 is electrically connected to the positive DC bus bar 5a on the DC power supply side. A connection point 12b paired with the series connection point 12 via the second capacitor unit 11 is electrically connected to the negative DC bus bar 5b on the DC power supply side.

[0016] (Figs. 2, 3) The first capacitor unit 10 includes a capacitor element Cy-p1 (first capacitor element) and a capacitor element Cy-p2 (second capacitor element) that are electrically connected in series. Similarly, the second capacitor unit 11 includes a capacitor element Cy-n1 (first capacitor element) and a capacitor element Cy-n2 (second capacitor element) that are electrically connected in series. In this way, the Y capacitor unit is configured by dividing the capacitor elements on the positive side into two and the capacitor elements on the negative side into two and electrically connecting them in series with each other.

[0017] The common-mode current 21 flows from the positive DC bus bar 5a through the connection point 12a to the first capacitor unit 10 and from the negative DC bus bar 5b through the connection point 12b to the second capacitor unit 11 along the direction of the arrow in FIG. 2. Then, the common-mode current 21 flows from the first capacitor unit 10 and the second capacitor unit 11 to the case ground through the series connection point 12.

[0018] As shown in FIG. 3, the first capacitor unit 10 and the second capacitor unit 11 are respectively housed in capacitor cases 19a and 19b. The first capacitor unit 10 is housed in the first capacitor case 19a, and the second capacitor unit 11 is housed in the second capacitor case 19b. The capacitor cases 19a and 19b are respectively filled with a sealing resin 20 having insulation performance, which seals the first capacitor unit 10 and the second capacitor unit 11 respectively. By doing so, the insulation between each capacitor unit and the case 18 of the power conversion device 1 is ensured.

[0019] In the first capacitor unit 10, the capacitor element Cy-p1 has a connection terminal 16a connected to the DC power supply side as the first terminal, and the capacitor element Cy-p2 has a ground terminal 17 connected to the ground potential side as the second terminal. A heat conduction member 13 is provided between the capacitor element Cy-p1 and the capacitor element Cy-p2, so that the capacitor element Cy-p1 and the capacitor element Cy-p2 are thermally connected to each other. The capacitor element Cy-p1 and the capacitor element Cy-p2 are arranged adjacent to each other in the capacitor case 19a.

[0020] In the first capacitor unit 10, when viewed in the elevation direction, the connection terminal 16a and the ground terminal 17 are arranged parallel to each other and face each other through a predetermined space. The capacitor element Cy-p1 and the capacitor element Cy-p2 are electrically connected in series through the electrode surface 14 and the conductive member 15. Thereby, the connection terminal 16a and the ground terminal 17 are electrically connected in series.

[0021] Also, in the second capacitor unit 11, the capacitor element Cy-n1 has a connection terminal 16b connected to the DC power supply side as the first terminal, and the capacitor element Cy-n2 has a ground terminal 17 connected to the ground potential side as the second terminal. A heat conduction member 13 is provided between the capacitor element Cy-n1 and the capacitor element Cy-n2, so that the capacitor element Cy-n1 and the capacitor element Cy-n2 are thermally connected to each other. The capacitor element Cy-n1 and the capacitor element Cy-n2 are arranged adjacent to each other within the capacitor case 19b.

[0022] In the second capacitor unit 11, when viewed in the elevation direction, the connection terminal 16b and the ground terminal 17 are arranged parallel to each other and face each other with a predetermined space therebetween. The capacitor element Cy-n1 and the capacitor element Cy-n2 are electrically connected in series via the electrode surface 14 and the conductive member 15. Thereby, the connection terminal 16b and the ground terminal 17 are electrically connected in series.

[0023] In this way, the connection terminal 16a and the ground terminal 17 in the first capacitor unit 10 and the connection terminal 16b and the ground terminal 17 in the second capacitor unit 11 are arranged such that the terminals are parallel to each other and overlapped, so that the facing area increases. Therefore, the common mode currents flowing through the respective terminals are in opposite directions to each other, and the parasitic inductance of the terminals is reduced by the mutual inductance.

[0024] Note that the predetermined space provided between the connection terminal 16a and the ground terminal 17 in the first capacitor unit 10 and between the connection terminal 16b and the ground terminal 17 in the second capacitor unit 11 may be made as close as possible between the terminals as long as the insulation distance between the terminals can be ensured. Thereby, it is possible to contribute to the miniaturization of the power conversion device 1.

[0025] Further, even if the heat conduction member 13 has a shape such as a heat dissipation sheet with a small thickness, it is only necessary that the capacitor element can dissipate heat, and there is no particular limitation as long as it is a material with high thermal conductivity. By doing so, even if the capacitor element is divided into two parts, an increase in size can be prevented, contributing to miniaturization.

[0026] In the first capacitor unit 10, the capacitor element Cy-p1 is electrically connected to the positive DC bus bar 5a via the connection terminal 16a and the electrode surface 14. The capacitor element Cy-p2 is electrically connected to the case 18 of the power conversion device 1 via the ground terminal 17 and the electrode surface 14 (see FIG. 4 described later).

[0027] In the second capacitor unit 11, the capacitor element Cy-n1 is electrically connected to the negative DC bus bar 5b via the connection terminal 16b and the electrode surface 14. The capacitor element Cy-n2 is electrically connected to the case 18 of the power conversion device 1 via the ground terminal 17 and the electrode surface 14 (see FIG. 4 described later).

[0028] Since the positive DC bus bar 5a and the negative DC bus bar 5b generate heat, heat is transferred to the capacitor element Cy-p1 and the capacitor element Cy-n1 via the connection terminal 16a and the connection terminal 16b. However, the capacitor element Cy-p1 and the capacitor element Cy-p2, and the capacitor element Cy-n1 and the capacitor element Cy-n2 are thermally connected to each other via the heat conduction member 13. As a result, the heat of the capacitor element Cy-p1 and the capacitor element Cy-n1 can be dissipated from the ground terminal 17 to the case 18 via the capacitor element Cy-p2 and the capacitor element Cy-n2, respectively. Thereby, heat received from the DC power supply side can be efficiently dissipated to the ground potential side, eliminating thermal bias in the Y capacitor unit.

[0029] (FIG. 4) FIG. 4(a) is an overall perspective view showing the electrical connection relationship between each capacitor unit provided on the case 18 of the power conversion device 1, the DC bus bar 5, and the case 18, and FIG. 4(b) is a cross-sectional view taken with the capacitor element Cy-p2 as a reference in FIG. 4(a).

[0030] (Modified Example) (FIG. 5) The first capacitor unit 10 and the second capacitor unit 11 may be collectively housed and arranged in one capacitor case 19. In this configuration, within the capacitor case 19, the first capacitor unit 10 and the second capacitor unit 11 are adjacent to each other via a sealing resin 20 to ensure insulation. At this time, the common mode currents 21 flowing through the capacitor element Cy-p1 and the capacitor element Cy-n2 flow in opposite directions to each other. Thereby, the parasitic inductance can be reduced by the mutual inductance.

[0031] According to the embodiments of the present invention described above, the following operational effects are achieved.

[0032] (1) A capacitor unit having a first terminal 16 and a second terminal 17, wherein the first terminal 16 is connected to the DC power supply side and the second terminal 17 is connected to the ground potential side, and includes a first capacitor element and a second capacitor element. The first capacitor element includes the first terminal 16, the second capacitor element includes the second terminal 17, the first terminal 16 and the second terminal 17 are electrically connected in series, and between the first capacitor element and the second capacitor element, a heat conducting member 13 that thermally connects the first capacitor element and the second capacitor element is provided. The first terminal 16 and the second terminal 17 are arranged parallel to each other when viewed in the elevation direction. By doing so, a capacitor unit that achieves both improved heat dissipation and reduced inductance can be provided.

[0033] (2) The first terminal 16 and the second terminal 17 face each other via a predetermined space. By doing so, an insulation distance can be ensured.

[0034] (3) The capacitor unit is arranged inside the capacitor case 19. By doing so, the insulation between each capacitor unit and the case 18 of the power conversion device 1 is ensured.

[0035] (4) A plurality of capacitor units are arranged inside the capacitor case 19. By doing so, even if a plurality of capacitor units are arranged in one capacitor case 19, it is possible to achieve both improved heat dissipation and reduced inductance.

[0036] Note that the present invention is not limited to the above-described embodiments, and various modifications and other configurations can be combined within the scope not departing from the gist thereof. Further, the present invention is not limited to those having all the configurations described in the above embodiments, and those in which a part of the configuration is deleted are also included.

Explanation of Reference Numerals

[0037] 1 Power conversion device 2 Electric drive motor 3 High-voltage battery 4 Power conversion circuit section 5 DC bus bar 5a Positive DC bus bar 5b Negative DC bus bar 6 DC input terminal 7 Smoothing capacitor 8 Noise filter circuit 9 X-capacitor group 10 First capacitor unit 11 Second capacitor unit 12 Series connection point 12a Connection point (positive electrode side) 12b Connection point (negative electrode side) 13 Heat conduction member 14 Electrode surface 15 Conductive member 16 DC connection terminal 16a Connection terminal (first capacitor unit) 16b Connection terminal (second capacitor unit) 17 Grounding terminal 18 Case 19 Capacitor case 19a First capacitor case 19b Second capacitor case 20 Encapsulating resin 21 Common mode current Cy-p1 Capacitor element Cy-p2 Capacitor element Cy-n1 Capacitor element Cy-n2 Capacitor element

Claims

1. A capacitor unit having a first terminal and a second terminal, wherein the first terminal is connected to a DC power supply side and the second terminal is connected to a ground potential side, comprising a first capacitor element and a second capacitor element, wherein the first capacitor element includes the first terminal, wherein the second capacitor element includes the second terminal, wherein the first terminal and the second terminal are electrically connected in series, wherein a heat conducting member for thermally connecting the first capacitor element and the second capacitor element is provided between the first capacitor element and the second capacitor element, wherein the first terminal and the second terminal are arranged parallel to each other when viewed in the elevation direction capacitor unit.

2. The capacitor unit according to claim 1, wherein the first terminal and the second terminal face each other with a predetermined space therebetween capacitor unit.

3. The capacitor unit according to claim 1, wherein the capacitor unit is arranged within a capacitor case capacitor unit.

4. The capacitor unit according to claim 1, wherein a plurality of the capacitor units are arranged within the capacitor case capacitor unit.

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