Power Conversion Device

Abstract

This power conversion device comprises a plurality of power modules, a plurality of smoothing capacitors, a first DC busbar, and a second DC busbar. The first and second DC busbars have positive and negative electrode busbars stacked on each other. The plurality of smoothing capacitors are disposed between the first DC busbar and the power modules. The first DC busbar has: a protruding portion passing between the plurality of smoothing capacitors and extending to the side on which the power modules are disposed; and a first connection portion connecting to the smoothing capacitors. The protruding portion has a second connection portion connecting to the second DC busbar. The second DC busbar has a third connection portion connecting to the power modules and a fourth connection portion connecting to the second connection portion.

Description

[Technical Field]

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

[0002] In response to customer demands for size and vehicle layout, a two-story structure has been considered for power conversion devices, which is advantageous for miniaturization, ease of assembly, and EMC (Electromagnetic Compatibility) performance. For example, Patent Document 1, which is a conventional technology, discloses a power conversion device configuration in which the positive and negative bus bars are each individually connected to a power module and a capacitor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5961714 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, because the positive and negative bus bars are individually connected to the power module and capacitor, there are many connection points (screw fastening points) and the connection points are dispersed. Furthermore, the positive and negative bus bars, which are DC power wiring, are located far from the battery input position, which increases inductance, so it was necessary to suppress the increase in inductance without impairing the assemblability of the device. In view of this, an object of the present invention is to provide a power conversion device that simultaneously achieves reduced inductance, compactness, and improved assemblability. [Means for solving the problem]

[0005] The power conversion device includes a plurality of power modules that convert DC power to AC power, a plurality of smoothing capacitors that smooth the DC power, a first DC bus bar connected to the plurality of smoothing capacitors, and a second DC bus bar connected to the plurality of power modules, wherein the first DC bus bar and the second DC bus bar have positive and negative bus bars stacked on each other, and the plurality of smoothing capacitors are arranged between the first DC bus bar and the power modules, and the first DC bus bar has a convex portion extending through between the plurality of smoothing capacitors toward the side where the power modules are arranged, and a first connection portion that connects to the smoothing capacitor on the surface of the smoothing capacitor opposite the side where the power modules are arranged, and the convex portion has a second connection portion that connects to the second DC bus bar, and the second DC bus bar has a third connection portion that connects to the power module and a fourth connection portion that connects to the second connection portion. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a power conversion device that simultaneously achieves reduced inductance, miniaturization, and improved assembly ease. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is an exploded perspective view of a power conversion device according to an embodiment of the present invention. [Figure 2] FIG. 4 is an explanatory diagram of a first DC bus bar. [Figure 3] 10A and 10B are diagrams illustrating the laminate structure of the positive and negative bus bars in the first DC bus bar. [Figure 4] FIG. 10 is an explanatory diagram of a second DC bus bar. [Figure 5] 10A and 10B are diagrams illustrating connections between a first DC bus bar, a second DC bus bar, and a power module. [Figure 6] 1 is an explanatory diagram of a power conversion device that houses a first DC bus bar and a second DC bus bar. [Figure 7] 7 is a cross-sectional view taken along line CC of the power converter shown in FIG. 6 according to one embodiment of the present invention.

[0008] Hereinafter, an embodiment 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 some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0009] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0010] (One embodiment of the present invention and overall configuration) (Figure 1) The power conversion device 100 includes a first DC bus bar 1, a noise filter 2, a smoothing capacitor 3, a DC circuit housing member 4 (hereinafter referred to as case 4), a second DC bus bar 5, a DC connector 6, an AC sensor 7, a power module 8, an AC bus bar 9, and a housing 10.

[0011] The housing 10 accommodates the components of the power conversion device 100 described above. Furthermore, by arranging the components inside the housing 10, the housing 10 has the function of forming a cooling flow path (not shown) that cools the entire power conversion device 100. By arranging the power module 8 on this cooling flow path and fixing it with screws, the power module 8 that generates heat can be cooled.

[0012] The power module 8 converts DC power input from outside into AC power. The power module 8 is also electrically connected to an AC bus bar 9 formed along the inner wall of the housing 10. The AC bus bar 9 is wired through the center of the AC sensor 7, which has a through-hole shape, so that the AC sensor 7 can measure the AC power flowing through the AC bus bar 9.

[0013] A second DC bus bar 5 is disposed between the two power modules 8 arranged inside the housing 10. The second DC bus bar 5 is electrically connected to the two power modules 8. The case 4 is a metal storage member, and is fixed to the housing 10 with screws. The case 4 houses and arranges the first DC bus bar 1, noise filter 2, and smoothing capacitor 3, and functions as a DC circuit unit.

[0014] The first DC bus bar 1 is electrically connected to a smoothing capacitor 3, which smoothes the DC power flowing through the first DC bus bar 1. The noise filter 2 is electrically connected to a DC connector 6. The first DC bus bar 1 and a second DC bus bar 5 are electrically connected.

[0015] (Figure 2) FIG. 2(a) is a perspective view of the first DC bus bar 1, and FIG. 2(b) is a cross-sectional view taken along line AA in FIG. 2(a). In the first DC bus bar 1, a bushing 11 and an insertion nut 15 are molded from resin as attachment parts to the case 4 and to components such as the smoothing capacitor 3. The bushing 11 functions as a buffer when the first DC bus bar 1 is connected to the case 4. The insertion nut 15 functions as a fastening part when connecting the first DC bus bar 1 to a harness (not shown). The first DC bus bar 1 is fixed to the case 4, which houses the noise filter 2 and the smoothing capacitor 3, with screws, bolts, or the like.

[0016] The first DC bus bar 1 has a positive bus bar 13 and a negative bus bar 14 formed from copper or other metal. The positive bus bar 13 and the negative bus bar 14 each have a welding terminal for connection to the noise filter 2 and the smoothing capacitor 3. By connecting the first DC bus bar 1 and the smoothing capacitor 3 by welding in this way, the laminated area on the smoothing capacitor 3 side can be increased while also being miniaturized.

[0017] The positive bus bar 13 and the negative bus bar 14 are stacked on top of each other, but to ensure insulation, PPS (Polyphenylenesulfide) or other resin is insert molded 16 between the positive bus bar 13 and the negative bus bar 14. The first DC bus bar 1 is also overmolded 12 with PPS or other resin.

[0018] The first DC bus bar 1 has a convex portion 17 with a U-shaped cross section. The U-shape of the convex portion 17 refers to a deep recessed shape that has a convex cross section, and means a drawn shape with a total of three surfaces in cross section, including a connection surface with the bus bar (second DC bus bar 5) to which the first DC bus bar 1 is connected and two surfaces erected from the connection surface.

[0019] The first DC bus bar 1 is electrically connected to the second DC bus bar 5 using the protrusion 17. This increases the area of the connection portion with the second DC bus bar 5. In addition, the first DC bus bar 1 has a U-shape of the protrusion 17, which also increases the overall stacking area of the positive bus bar 13 and the negative bus bar 14.

[0020] By molding the first DC bus bar 1 as a single piece, the surface area can be increased compared to molding it in parts, and the number of fixing points (connection points) can also be reduced, thereby reducing inductance and contributing to a reduction in the number of parts.

[0021] (Figure 3) The first DC busbar 1 has a laminated structure in which the positive busbar 13 and the negative busbar 14 are stacked on top of each other. Each of the positive busbar 13 and the negative busbar 14 on the protruding portion 17 of the first DC busbar 1 has two sets of screw fastening points 1a, which are connection points with the second DC busbar 5. The two sets of screw fastening points 1a are spaced apart at a sufficiently wide interval, and the protruding portion 17 is given a width 17a in the left-right direction of the drawing, thereby increasing the area of the protruding portion 17 in the planar direction of the first DC busbar 1. This increases the laminated area of the positive busbar 13 and the negative busbar 14 on the first DC busbar 1, thereby reducing inductance.

[0022] (Figure 4) Fig. 4(a) is an overall perspective view of the second DC bus bar 5, and Fig. 4(b) is a B-B cross-sectional view of Fig. 4(a). The second DC bus bar 5 has U-shaped positive and negative bus bars 13 and 14 made of copper or other metal, similar to the first DC bus bar 1. The positive and negative bus bars 13 and 14 of the second DC bus bar 5 each have two sets of screw fastening points 5a, which are connection points with the positive and negative bus bars 13 and 14 of the first DC bus bar 1.

[0023] When connecting the first DC bus bar 1 and the second DC bus bar 5, screws, bolts, etc. inserted into the screw fastening points 5a are inserted into insertion nuts 15 (prepared holes) formed inside the second DC bus bar 5. By providing a predetermined gap that ensures a sufficient distance between the two sets of screw fastening points 5a, the second DC bus bar 5 can increase the stacking area of the positive bus bar 13 and the negative bus bar 14, which can contribute to reducing inductance.

[0024] The second DC bus bar 5 is a molded product, and in order to ensure insulation, it is insert molded 16 by injecting PPS or other resin between the positive bus bar 13 and the negative bus bar 14. Similarly, the surface of the second DC bus bar 5 is overmolded 12 with PPS or other resin.

[0025] In the second DC bus bar 5, a bushing 11 and an insertion nut 15 are molded as an assembly portion for the housing 10 and an assembly portion for the first DC bus bar. The positive bus bar 13 and the negative bus bar 14 have welding terminals 18 for electrical connection with the power module 8. The second DC bus bar 5 is connected to the power module 8 by welding via the welding terminals 18.

[0026] The welding connection is made using a TIG (Tungsten Inert Gas) welding method, which simplifies assembly and contributes to miniaturization of the power conversion device 100, reduction of inductance, and improvement of EMC performance.

[0027] (Figure 5) The protrusion 17 of the first DC bus bar 1 is electrically connected to the second DC bus bar 5. The second DC bus bar 5 is disposed between the two power modules 8 and is electrically connected to the two power modules 8 by third connection portions 22 (welding terminals 18). The first DC bus bar 1 and the second DC bus bar 5 are electrically connected by being joined to each other with screws or the like.

[0028] (Figure 6) Fig. 6(a) is a diagram showing the state in which internal components are housed in the housing 10, and Fig. 6(b) is a diagram showing Fig. 6(a) as viewed from above inside the housing 10. The first DC bus bar 1 has a first connection portion 20 for connection to the smoothing capacitor 3. The first DC bus bar 1 and the smoothing capacitor 3 are electrically connected by being welded at the first connection portion 20.

[0029] The power conversion device 100 has a structure with a divided busbar shape, which is divided into the first DC busbar 1 and the second DC busbar 5, thereby reducing the number of connection points between the busbars, contributing to miniaturization and reducing inductance. In addition, the connection between the second DC busbar 5 and the power module 8 is made by welding, which increases the stacking area on the power module 8 side and eliminates the need for screw fastening.

[0030] (Figure 7) 7, the multiple smoothing capacitors 3 are arranged between the first DC bus bar 1 and the power modules 8. The first DC bus bar 1 has a protrusion 17 that passes between the multiple smoothing capacitors 3 and extends toward the side where the power modules 8 are arranged, and a first connection portion 20 that connects to the smoothing capacitor 3 on the surface of the smoothing capacitor 3 opposite the side where the power modules 8 are arranged. The smoothing capacitors 3 and the first DC bus bar 1 are connected by welding at the first connection portion 20.

[0031] The first DC bus bar 1 has a second connection portion 21 that connects to the second DC bus bar 5 at the protrusion 17. In addition, the second DC bus bar 5 has a fourth connection portion 23 that connects to the second connection portion 21 of the first DC bus bar 1. The first DC bus bar 1 and the second DC bus bar 5 are electrically connected to each other at the second connection portion 21 and the fourth connection portion 23.

[0032] The protrusion 17 of the first DC bus bar 1 and the second DC bus bar 5 each have a U-shaped cross section. The protrusion 17 and the second DC bus bar 5 are arranged so as to be connected to each other on the side opposite to the opening side of the U-shape.

[0033] The second DC bus bar 5 has a third connection portion 22. The second DC bus bar 5 is electrically connected to each of the two power modules 8 via the third connection portion 22 (welding terminals 18).

[0034] The first DC bus bar 1 and the second DC bus bar 5 are arranged so as to be covered by the case 4. The case 4 is arranged between the smoothing capacitor 3 and the power module 8. This arrangement reduces inductance due to the eddy current effect, and by arranging the case 4 between the smoothing capacitor 3 and the power module 8 equipped with a semiconductor device, a shielding effect is achieved using the metal plate shielding of the case 4 for the DC line formed by the electrical connection between the first DC bus bar 1 and the second DC bus bar 5, thereby improving EMC (Electromagnetic Compatibility) performance and reducing noise.

[0035] In this way, the bus bar connections between the multiple power modules 8 and the multiple smoothing capacitors 3 are concentrated in the center, which reduces the number of connection points (screw fastening points) compared to conventional devices, thereby not only reducing size but also inductance. Furthermore, by reducing the number of connection points and making the cross section U-shaped, the stacking area of the positive bus bar 13 and the negative bus bar 14 can be increased. Furthermore, because the connection between the first DC bus bar 1 and the second DC bus bar 5 can be located in the center of the device 100, in a dual inverter type configuration using two power modules 8 as described above, space can be used efficiently, contributing to size reduction.

[0036] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0037] (1) A power conversion device 100 includes a plurality of power modules 8 that convert DC power to AC power, a plurality of smoothing capacitors 3 that smooth the DC power, a first DC bus bar 1 connected to the plurality of smoothing capacitors 3, and a second DC bus bar 5 connected to the plurality of power modules 8. The first DC bus bar 1 and the second DC bus bar 5 have positive bus bars 13 and negative bus bars 14 stacked on top of each other. The plurality of smoothing capacitors 3 are arranged between the first DC bus bar 1 and the power modules 8. The first DC bus bar 1 has a protrusion 17 that passes between the plurality of smoothing capacitors 3 and extends toward the side where the power modules 8 are arranged, and a first connection portion 20 that connects to the smoothing capacitor 3 on the surface of the smoothing capacitor 3 opposite the side where the power modules 8 are arranged. The protrusion 17 has a second connection portion 21 that connects to the second DC bus bar 5. The second DC bus bar 5 has a third connection portion 22 that connects to the power module 8 and a fourth connection portion 23 that connects to the second connection portion 21. This makes it possible to provide a power conversion device 100 that simultaneously achieves reduced inductance, miniaturization, and improved assembly ease.

[0038] (2) The protrusion 17 of the first DC bus bar 1 and the second DC bus bar 5 each have a U-shaped cross section and are arranged so that they are connected to each other on the side opposite to the opening of the U. This allows the first DC bus bar 1 and the second DC bus bar 5 to be connected over a large area and allows the connection parts to be concentrated in one place.

[0039] (3) At least one of the first DC bus bar 1 and the second DC bus bar 5 is covered with a metal housing member 4. This reduces inductance due to the eddy current effect.

[0040] (4) The housing member 4 is disposed between the smoothing capacitor 3 and the power module 8. This provides a shielding effect, improving EMC performance and reducing noise.

[0041] (5) The smoothing capacitor 3 and the first DC bus bar 1 are connected by welding. This contributes to the miniaturization of the power conversion device 100.

[0042] (6) The power module 8 and the second DC bus bar 5 are connected by welding. This contributes to the miniaturization of the power conversion device 100.

[0043] The present invention is not limited to the above-described embodiments, and various modifications and combinations of other configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted. [Explanation of symbols]

[0044] 1. First DC bus bar 1a Screw fastening point 2. Noise Filter 3 smoothing capacitors 4 DC circuit housing (case) 5. Second DC bus bar 5a Screw fastening point 6 DC connector 7 AC Sensor 8 Power Module 9 AC bus bar 10. Housing 11 Bush 12 Overmolding 13 Positive bus bar 14 Negative bus bar 15 Insert Nut 16 Insert molding 17 Convex part 17a Width of the convex part 18 Welding terminal 20 First connection part 21 Second connection part 22 Third connection part 23 Fourth Connection 100 Power conversion device

Claims

1. a plurality of power modules that convert DC power into AC power; a plurality of smoothing capacitors for smoothing the DC power; a first DC bus bar connected to the plurality of smoothing capacitors; a second DC bus bar connected to the plurality of power modules, the first DC bus bar and the second DC bus bar have a positive bus bar and a negative bus bar stacked on each other, the smoothing capacitors are arranged between the first DC bus bar and the power module, the first DC bus bar has a convex portion extending toward the side where the power module is arranged through the plurality of smoothing capacitors, and a first connection portion connected to the smoothing capacitor on a surface of the smoothing capacitor opposite to the side where the power module is arranged, the protruding portion has a second connection portion that is connected to the second DC bus bar, The second DC bus bar has a third connection portion connected to the power module and a fourth connection portion connected to the second connection portion. Power conversion device.

2. The power conversion device according to claim 1, The protrusion of the first DC bus bar and the second DC bus bar each have a U-shaped cross section, and are arranged so as to be connected to each other on the side opposite to the opening side of the U-shape. Power conversion device.

3. The power conversion device according to claim 1, At least one of the first DC bus bar and the second DC bus bar is covered with a metal housing member. Power conversion device.

4. The power conversion device according to claim 3, The storage member is disposed between the smoothing capacitor and the power module. Power conversion device.

5. The power conversion device according to claim 1, The smoothing capacitor and the first DC bus bar are connected by welding. Power conversion device.

6. The power conversion device according to any one of claims 1 to 5, The power module and the second DC bus bar are connected by welding. Power conversion device.

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