Capacitor device

Abstract

Conventional capacitor devices had a problem where the mutual inductance between the busbar and the capacitor element decreased, resulting in a large ESL (Electronic Slip Level). [Solution] The capacitor device comprises a smoothing capacitor element 3 housed in a case 2 together with potting material 1, one and the other lead wires 4 and 5 connected to the smoothing capacitor element 3, and an upper busbar 6 and a lower busbar 7 stacked vertically, wherein the upper busbar 6 and the lower busbar 7 are electrically connected to the one and the other lead wires 4 and 5, and have downward-facing convex shapes with protruding regions 6B and 7B that are close to the potting material 1, thereby reducing the distance between the smoothing capacitor element 3 and the busbars 6 and 7, and canceling out the ripple current between the current flowing through the smoothing capacitor element 3 and the busbars 7 to reduce and suppress the ESL.

Description

Technical Field

[0001] The present invention relates to a capacitor device used in a power conversion device or the like.

Background Art

[0002] As a conventional capacitor device, for example, there is one described in Patent Document 1. Patent Document 1 describes a capacitor device having a structure in which a plurality of capacitors are arranged on a cooler, and a two-pole bus bar is arranged on each capacitor via a circuit board, and the lead wires, the circuit board, and the bus bar of each capacitor are electrically connected. This capacitor device dissipates heat from the capacitor by bringing the circuit board into thermal contact with the cooler.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described conventional capacitor device, when a capacitor provided with lead wires is connected to a simple parallel plate, the distance between the bus bar and the capacitor element becomes long, the mutual inductance between the bus bar and the capacitor element decreases, and there is a problem that the ESL (equivalent series inductance) increases. Solving such a problem has been an issue.

[0005] The present invention has been made in view of the above-described conventional situation, and is a capacitor device in which a smooth capacitor element is housed in a case together with a potting material, and the distance between the smooth capacitor element and the bus bar is reduced, and the ripple current between the current flowing through the smooth capacitor element and the bus bar is canceled out, and an object thereof is to provide a capacitor device capable of suppressing ESL. [Means for solving the problem]

[0006] The capacitor device according to the present invention comprises a smoothing capacitor element housed in a case together with a potting material, one and the other lead wires connected to the smoothing capacitor element and extending upwards from the case, and an upper busbar and a lower busbar stacked vertically on the upper side of the case in an insulated state from each other. The capacitor device is characterized in that the upper busbar and the lower busbar are electrically connected to the one and the other lead wires, respectively, and have a downward-facing convex shape with a protruding region that is close to the potting material. [Effects of the Invention]

[0007] The capacitor device according to the present invention, by adopting the above configuration, has a structure in which the smoothing capacitor element is housed in a case together with the potting material, thereby reducing the distance between the smoothing capacitor element and the busbar, and canceling out the ripple current between the current flowing through the smoothing capacitor element and the busbar, thereby suppressing the ESL to a small extent. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional explanatory diagram showing a first embodiment of a capacitor device. [Figure 2] This is an explanatory diagram showing a perspective view of a capacitor device on the left and a plan view including a cross-sectional view of the main parts on the right. [Figure 3] This is a cross-sectional diagram illustrating the current in a capacitor device. [Figure 4] This is a cross-sectional diagram illustrating a second embodiment of the capacitor device. [Figure 5] This is a cross-sectional diagram illustrating the main part of a third embodiment of a capacitor device. [Figure 6] This is a cross-sectional explanatory diagram of the main part showing the fourth embodiment of the capacitor device. [Figure 7] This is a perspective view showing a fifth embodiment of the capacitor device. [Figure 8] This is a perspective view showing the sixth embodiment of the capacitor device. [Figure 9] This is a perspective view showing the seventh embodiment of the capacitor device. [Figure 10] This is a perspective view showing the eighth embodiment of the capacitor device. [Modes for carrying out the invention]

[0009] <First Embodiment> The capacitor device shown in Figures 1 and 2 comprises a smoothing capacitor element 3 housed in a case 2 together with a potting material 1, lead wires 4 and 5 connected to the smoothing capacitor element 3 and extending upwards to the case 2, and an upper busbar 6 and a lower busbar 7 stacked vertically on the upper side of the case 2 in an insulated manner.

[0010] Case 2 is open on the top and is filled with a potting material 1, which is a resin, and houses a smoothing capacitor element 3 embedded in the potting material 1. The smoothing capacitor element 3 is, for example, a film capacitor, with one lead wire 4 (e.g., P pole) connected to one end on the left side in Figure 1, and the other lead wire 5 (e.g., N pole) connected to the other end. Both lead wires 4 and 5 extend to the top of Case 2 through the potting material 1.

[0011] As shown in the left diagram of Figure 2, the upper busbar 6 and the lower busbar 7 are metal plates large enough to cover the entire upper side of multiple (four in the illustrated example) cases 2 arranged in parallel, with an insulating member (not shown) interposed between them, and stacked with a gap between them. In the capacitor device shown in the example, the upper busbar 6 is electrically connected to one lead wire 4, and the lower busbar 7 is electrically connected to the other lead wire 5.

[0012] At this time, as shown in the right figure of Fig. 2, the upper bus bar 6 has an upper opening 6A that penetrates the other lead wire 5 connected to the lower bus bar 7 in a non-contact state. On the other hand, the lower bus bar 7 has a lower opening 7A that penetrates the one lead wire 4 connected to the upper bus bar 6 in a non-contact state.

[0013] Note that the upper opening 6A and the lower opening 7A have a size sufficient to allow the lead wires 4 and 5 to penetrate in a non-contact manner. In addition to the rectangular shape in the illustrated example, they can have various shapes such as circular, and an insulating material can be interposed between the lead wires 4 and 5 to achieve more reliable insulation.

[0014] And the upper and lower bus bars 6 and 7 in the above capacitor device have protruding regions 6B and 7B that form a downward convex shape and are close to the potting material 1. Since the bus bars 6 and 7 in the illustrated example are formed by inverting the front and back shapes of a metal plate as the material, the back side of the protruding regions 6B and 7B is a flat concave region. The protruding regions 6B and 7B form a rectangular shape that fits between the one and the other lead wires 4 and 5, and are formed for each of the cases 2 arranged in parallel with respect to the bus bars 6 and 7.

[0015] Also, the upper and lower bus bars 6 and 7 have a gap between each other over the entire region including the protruding regions 6B and 7B. By minimizing the distance between the two as much as possible, the ripple current with a variable direction between the lead wires 4 and 5 is canceled out. In particular, the lower bus bar 7 has a protruding region 7B that is slightly larger than the protruding region 6B of the upper bus bar 6, and the lower surface of this protruding region 7B is brought as close as possible to the surface of the potting material 1.

[0016] Furthermore, as shown in Fig. 3, the above capacitor device has a smoothing capacitor element 3 connected between the semiconductor module M and the high-power battery B. In the illustrated example, for both bus bars 6 and 7, the semiconductor module M is connected to the one lead wire 4 side on the right side in Fig. 3, and the high-power battery B is connected to the other lead wire 5 side.

[0017] As shown in Fig. 3, in the capacitor device having the above structure, currents indicated by arrows A1 to A6 flow from the semiconductor module M side. That is, in the capacitor device, as indicated by arrow A1, current flows from the semiconductor module M side to the upper bus bar 6, as indicated by arrow A2, current flows to one lead wire 4, and as indicated by arrow A3, current flows from one end side to the other end side of the smoothing capacitor element 3.

[0018] Then, in the capacitor device, as indicated by arrow A4, current flows to the other lead wire 5, as indicated by arrow A5, current flows to the lower bus bar 7, and as indicated by arrow A6, current flows from the lower bus bar 7 to the semiconductor module M side.

[0019] The above capacitor device has a structure in which the distance between the smoothing capacitor element 3 and the lower bus bar 7 is minimized by forming protruding regions 6B and 7B in the upper and lower bus bars 6 and 7. Also, since the direction of the current in the smoothing capacitor element 3 (arrow A3) and the direction of the current in the lower bus bar 7 (arrow A5) are opposite to each other, the ripple currents can cancel each other out between the two, and thus the ESL (equivalent series inductance) can be suppressed to be small.

[0020] In addition, in the above capacitor device, usually, it is difficult to manage variations in adjusting the liquid level height of the potting material 1 enclosed in the case 2. Therefore, the connection portions of the bus bars 6 and 7 and the lead wires 4 and 5 are arranged above the case 2 to avoid interference with the potting material 1, and by providing the protruding regions 6B and 7B in the bus bars 6 and 7, the lower bus bar 7 can be made close to the potting material 1.

[0021] For example, this structure is applied to an inverter of a vehicle drive motor and is arranged between the semiconductor module M and the high - voltage battery B. Since the capacitor device described above is placed between the semiconductor module M and the high-voltage battery B, current flows from the semiconductor module M side to the high-voltage battery B side through the smoothing capacitor element 3, and current flows from the high-voltage battery B side to the semiconductor module M side through the lower busbar 7. As a result, as mentioned above, the directions of the currents flowing through the smoothing capacitor element 3 and the lower busbar 7 are opposite to each other, and the ripple current can be canceled out.

[0022] Furthermore, the above capacitor device may also be configured with the busbars 6 and 7 connected to the lead wires 4 and 5 reversed. In this case, although the distance between the smoothing capacitor element 3 and the upper busbar 6 will be slightly larger, the direction of the current flowing through the smoothing capacitor element 3 and the upper busbar 6 will be opposite to each other, making it possible to obtain a ripple current cancellation effect.

[0023] Furthermore, the above-described capacitor device is provided with upper busbar 6 and lower busbar 7, respectively, with upper openings 6A and 7A that allow the lead wires 4 and 5 connected to the other side to pass through without contact, thereby ensuring insulation between the respective busbars 6 and 7 and the lead wires 4 and 5.

[0024] Figures 4 to 10 illustrate the second to eighth embodiments of the capacitor device according to the present invention. In the following embodiments, the same reference numerals are used for the same parts as in the first embodiment, and detailed descriptions are omitted.

[0025] <Second Embodiment> The capacitor device shown in Figure 4 has the same basic configuration as the first embodiment, and includes a resin molded body 10 that covers the upper and lower busbars 6 and 7 with the protruding region 7B of the lower busbar 7 exposed on the lower side. In addition, the capacitor device shown in the example has a sheet-shaped heat dissipation material 11 placed between the protruding region 7B of the lower busbar 7 and the potting material 1.

[0026] A capacitor device with the above configuration can achieve the same effects as the first embodiment, and the protruding region 7B of the lower busbar 7 can be brought closer to the potting material 1. This makes it easier to cancel out ripple currents and to dissipate heat generated by the smoothing capacitor element 3 through the lower busbar 7. In addition, the capacitor device shown in the example can also improve heat dissipation performance by making the heat dissipation material 11 thinner due to the protruding region 7B.

[0027] <Third Embodiment> The capacitor device shown in Figure 5 has the same basic configuration as the second embodiment, and the resin molded body 10 has a projection 10A on its lower surface that abuts against the inner surface of the protruding region 7B of the lower busbar 7. In the illustrated example, the capacitor device has three projections 10A at predetermined intervals that abut against the middle part of the protruding region 7B.

[0028] In the capacitor device described above, as previously mentioned, it is difficult to control the height of the potting material 1 filled inside case 2. Consequently, it becomes difficult to position the busbars 6 and 7 and the lead wires 4 and 5 in the height direction, and to position the lower busbar 7 and the potting material 1 in close proximity.

[0029] Here, the connection between busbars 6 and 7 and lead wires 4 and 5 is made by local joining using solder or welding. However, to avoid situations where stress is applied to the joint, the input is absorbed by the upward convex deformation of busbar 7. However, if the input is absorbed by the deformation of busbar 7, if the amount of deformation is not regulated, excessive stress will be applied, making it difficult to maintain the insulation distance between the upper and lower busbars 6 and 7.

[0030] In contrast, the capacitor device described above can achieve the same effects as the second embodiment, and by providing a projection 10A on the resin molded body 10, the positions of the protruding regions 6B and 7B on the upper and lower busbars 6 and 7 can be reliably restricted, and a good insulation distance can be maintained over a long period of time.

[0031] <Fourth Embodiment> The capacitor device shown in Figure 6 has the same basic configuration as the second embodiment, and the resin molded body 10 has a projection 10A on its lower surface that abuts against the inner surface of the protruding region 7B of the lower busbar 7. In the illustrated example, the capacitor device has two projections 10A on the resin molded body 10 that abut against both ends of the protruding region 7B.

[0032] The above capacitor device can achieve the same effects as the second embodiment, and, similar to the third embodiment, can reliably regulate the positions of the protruding regions 6B and 7B in the upper and lower busbars 6 and 7 to maintain the insulation distance. The position and number of protrusions 10A in the resin molded body 10 can be appropriately set according to the dimensions between the lead wires 4 and 5 of the smoothing capacitor element 3 and variations in the potting material 1.

[0033] <Embodiments 5-8> The capacitor device shown in Figure 7 comprises a single case 2 containing a smoothing capacitor element 3 along with potting material, and has an upper and lower busbar configuration with the upper and lower busbars 6 and 7 arranged within this case 2.

[0034] The capacitor device shown in Figure 8 comprises two cases 2, each containing two smoothing capacitor elements 3, 3 connected to each other along with potting material, and has an upper and lower busbar configuration with busbars 6, 7 positioned on these cases 2.

[0035] The capacitor device shown in Figure 9 comprises a single case 2 containing four smoothing capacitor elements 3 along with potting material, and has an upper and lower busbar configuration with upper and lower busbars 6 and 7 arranged on this case 2.

[0036] The capacitor device shown in Figure 10 comprises a case 2 containing two sets of two smoothing capacitor elements 3, 3 connected to each other with potting material, and has an upper and lower busbar configuration arranged on this case 2.

[0037] Thus, the capacitor device can adopt various combinations in terms of the number and connection structure of the case 2 and the smoothing capacitor element 3. In FIGS. 7 to 10, the directions of the pair of lead wires 4 and 5 are shown to be the same, but it is also possible to include those in which the directions of the pair of lead wires 4 and 5 are different, and in any case, the same effects as those of the first embodiment can be obtained.

[0038] Note that the configuration of the capacitor device according to the present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist of the present invention, and it is also possible to combine the configurations of the respective embodiments.

Explanation of Reference Numerals

[0039] 1 Potting material 2 Case 3 Smoothing capacitor element 4 One lead wire 5 The other lead wire 6 Upper bus bar 6A Upper opening 6B Protruding region 7 Lower bus bar 7A Lower opening 7B Protruding region 10 Resin mold body 10A Protrusion B High-voltage battery M Semiconductor module

Claims

1. A smoothing capacitor element housed in a case along with potting material, One and the other lead wires are connected to the smoothing capacitor element and extend upward to the case, The case comprises an upper busbar and a lower busbar stacked vertically in an insulated manner from each other on the upper side, A capacitor device characterized in that the upper busbar and the lower busbar are electrically connected to the lead wires of one and the other, respectively, and each has a downward convex shape with a protruding region that is close to the potting material.

2. The capacitor device according to claim 1, characterized in that the smoothing capacitor element is connected between the semiconductor module and the high-voltage battery.

3. The upper busbar has an upper opening through which the other lead wire connected to the lower busbar passes in a non-contact manner. The capacitor device according to claim 1, characterized in that the lower busbar has a lower opening through which one of the lead wires connected to the upper busbar passes in a non-contact state.

4. The capacitor device according to claim 1, further comprising a resin molded body that covers the upper and lower busbars while exposing the protruding region of the lower busbar to the lower surface.

5. The capacitor device according to claim 4, characterized in that the resin molded body has a projection on its lower surface that contacts the inner surface of the protruding region of the lower busbar.

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