Power converter

Abstract

This invention provides a power conversion device that uses aluminum for the busbars while allowing the busbars to be connected to the main terminals of a power module made of copper. [Solution] A power conversion device comprising a power module 100 having a main terminal 1 made of copper, a busbar body 22 made of aluminum, and a busbar connection part 21 made of copper, wherein the main terminal 1 and the busbar connection part 21 are welded together, and the busbar connection part 21 and the busbar body 22 are joined by a crimping part 3.

Description

Technical Field

[0001] This disclosure relates to a power conversion device.

Background Art

[0002] As a method for reducing the cost and weight of an in-vehicle inverter, there is aluminization of copper busbars. In an in-vehicle inverter, copper is generally used for the main terminals from the viewpoints of conductivity, strength, and formability. The busbar arranged opposite to the power module and welded to the main terminal is selected to be copper, which is the same material as the main terminal of the power module 1, due to production constraints of welding. Since an aluminum material has the property of generating an oxide film with a very high melting point, it is difficult to weld. Also, since the main terminal requires high conductivity, cooling property, and soldering property, an aluminum material cannot be used. On the other hand, Patent Document 1 discloses a technique for fixing a copper material and a resin plate by caulking a protrusion of a resin plate sandwiched between two flat copper materials.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technique of Patent Document 1 arranges a resin plate between two flat copper busbars arranged in parallel with a gap therebetween to reduce inductance. Then, a protrusion is provided on the resin plate, the protrusion is inserted into a through-hole of one copper busbar, and the tip of the protrusion is caulked to fix the copper material and the resin plate. However, among the structural materials used in the configuration of an in-vehicle inverter, the copper material has a high material cost and a high specific gravity, resulting in an increase in weight.

[0005] Therefore, the present disclosure aims to provide a power conversion device that uses aluminum for the busbar while allowing the busbar to be connected to the main terminal of a power module using copper. [Means for solving the problem]

[0006] A power module having a main terminal containing copper as a material, The busbar body is made of aluminum, It includes a busbar connector made of copper, The main terminal and the busbar connection portion are welded together. A power conversion device in which the busbar connection portion and the busbar body portion are joined by a crimping portion. [Effects of the Invention]

[0007] According to this disclosure, a new copper busbar connection section is provided between the aluminum busbar body and the copper power module's main terminal. The main terminal and the busbar connection section are welded together, and the busbar connection section and the busbar body are joined by a crimping section. This allows the busbar to be connected to the copper power module's main terminal while still using aluminum for the busbar. Therefore, cost reduction and weight reduction are possible compared to using only copper for the busbar. Furthermore, since the busbar connection section, rather than the main terminal, is crimped, there is no need to change the shape of the main terminal for crimping, and the busbar connection section can be shaped to be suitable for crimping and connection. This allows for cost reduction and weight reduction compared to a busbar shape made only of copper. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of the power module and busbar of a comparative example according to Embodiment 1. [Figure 2] This is a perspective view showing the configuration of the power conversion device according to Embodiment 1. [Figure 3] This is a cross-sectional view showing a rivet crimp, which is an example of a crimped part in the configuration of the power conversion device according to Embodiment 1. [Figure 4]This is a cross-sectional view showing a spot crimp, which is an example of a crimping section in the configuration of the power conversion device according to Embodiment 1. [Figure 5] This is a perspective view showing the configuration of the power conversion device according to Embodiment 2. [Figure 6] This is a perspective view showing the configuration of the power conversion device according to Embodiment 3. [Figure 7] This is a perspective view showing the configuration of the power conversion device according to Embodiment 4. [Figure 8] This is a perspective view showing the configuration of the power conversion device according to Embodiment 5. [Figure 9] This is a perspective view of the busbar of a comparative example according to Embodiment 6. [Figure 10] This is a perspective view showing the configuration of the power conversion device according to Embodiment 6. [Modes for carrying out the invention]

[0009] 1. Embodiment 1 A power conversion device according to Embodiment 1 will be described with reference to the drawings. Figure 1 is a perspective view of a comparative example power module 100 and busbar 2 according to Embodiment 1. Figure 2 is a perspective view showing the configuration of the power conversion device according to Embodiment 1. Figure 3 is a cross-sectional view showing a rivet crimp, which is an example of the crimping part 3 in the configuration of the power conversion device according to Embodiment 1. Figure 4 is a cross-sectional view showing a spot crimp, which is an example of the crimping part 3 in the configuration of the power conversion device according to Embodiment 1.

[0010] 1-1. Configuration of a power converter The power converter comprises a power module 100 having a main terminal 1 made of copper, a busbar body 22 made of aluminum, and a busbar connection 21 made of copper. The main terminal 1 and the busbar connection 21 are welded together, and the busbar connection 21 and the busbar body 22 are joined by a crimping portion 3.

[0011] In the present disclosure, the direction in which the main terminal 1 extends from the power module 100 is defined as one side X1 of the first direction, and the opposite side of one side X1 of the first direction is defined as the other side X2 of the first direction. The direction in which one side of the main terminal 1 abuts against one side of the bus bar connection portion 21 and the other side of the bus bar connection portion 21 protrudes is defined as one side Y1 of the second direction, and the opposite side of one side Y1 of the second direction is defined as the other side Y2 of the second direction.

[0012] <Power module> The power module 100 of the present disclosure has a main body portion, a main terminal 1, and a control terminal. The main body portion has a switching element, a connection circuit, etc., is sealed with a molding resin, and is formed in a rectangular plate shape. The main terminal 1 is an external connection terminal of the connection path of the current flowing through the switching element. In this example of the power module 100, as shown in FIG. 1, it has three main terminals 1, and the connection of one of the main terminals 1 to the bus bar 2 will be described in detail. The control terminal is an external connection terminal to which a control signal used for on / off control of the switching element, etc. is input / output. In this example of the power module 100, it has twelve control terminals.

[0013] As described above, the main terminal 1 contains copper in its material. For example, copper or a copper alloy is used as the material. As shown in FIG. 1, the main terminal 1 of the power module is formed in a rectangular plate shape and protrudes from the main body portion to one side X1 of the first direction. The bus bar connection portion 21 is joined to the main terminal 1 by welding. Similar to the main terminal 1, the bus bar connection portion 21 contains copper in its material. For example, copper or a copper alloy is used as the material.

[0014] The power module 100 shown in this embodiment is mounted on, for example, an in-vehicle inverter, etc., and converts current from direct current to alternating current. The current flowing through the main terminal 1 of the power module 100 flows through the bus bar connection portion 21 and the bus bar main body portion 22. The end portion of one side X1 of the first direction of the main terminal 1 abuts against the bus bar connection surface 21a on one side of the bus bar connection portion 21 on one side Y1 of the second direction and is joined by welding.

[0015] <Bus bar> As shown in Fig. 1, the bus bar 2 of the comparative example is formed in a U shape, and the entire bus bar 2 is made of copper. The bus bar 2 has a flat surface on one side for connecting to the main terminal 1 of the power module, and the main terminal 1 and the bus bar connection surface 21a are in contact and welded. The bus bar 2 has a connection hole 22a on the other side into which screws, connection terminals, etc. are inserted, and the current is connected to each circuit and device.

[0016] <Bus bar connection part> In this embodiment, the bus bar 2 is divided into a bus bar connection part 21 and a bus bar main body part 22, and the material of the bus bar connection part 21 is made of copper. The bus bar connection part 21 is a connecting member that connects the above-mentioned main terminal 1 and the bus bar main body part 22 described below. One side of the bus bar connection part 21 abuts against the main terminal 1, and the other side abuts against the bus bar main body part 22. One side of the bus bar connection part 21 has a flat surface for abutting against the main terminal 1. The other side of the bus bar connection part 21 abuts against the bus bar main body part 22 and is fixed by caulking part 3. The other side of the bus bar connection part 21 is formed in a plate shape in this example so that it can abut against the bus bar main body part 22 and be caulked. In the case of rivet caulking, a hole 2 through which the rivet penetrates is provided in the plate-shaped part on the other side of the bus bar connection part 21, and in the case of spot caulking, the plate-shaped part on the other side of the bus bar connection part is deformed by caulking. One side of the bus bar connection part 21 extends from the bent part to one side X1 in the first direction, and the other side of the bus bar connection part 21 extends from the bent part to one side Y1 in the second direction.

[0017] <Bus bar main body part> The busbar body portion 22 contains aluminum as its material. For example, aluminum or an aluminum alloy can be used as the material. By forming the busbar body portion 22 from aluminum, cost reduction and weight reduction can be expected compared to the comparative example busbar 2 made only of copper shown in Figure 1. As shown in Figure 2, the busbar body portion 22 has a connection hole 22a at the other end and a flat surface at the other end. The other side of the busbar body portion 22 abuts against the busbar connection portion 21, and in this example, it is formed in a plate shape so that the crimping portion 3 can be installed at the abutting position, similar to the other side of the busbar connection portion 21. On the other side of the busbar body portion 22, similar to one side of the busbar connection portion 21, in the case of rivet crimping, a hole is provided in the plate-shaped portion on the other side of the busbar connection portion 21 through which the rivet passes, and in the case of spot crimping, the plate-shaped portion on the other side of the busbar connection portion 21 is deformed by crimping. The busbar body 22 is formed into an L-shape by bending the portion between one side and the other side of the busbar body 22. One side of the busbar connection portion 21 extends from the bent portion to the other side Y2 in the second direction, and the other side of the busbar connection portion 21 extends from the bent portion to the one side X1 in the first direction.

[0018] As mentioned above, the types of crimping parts 3 to be installed include rivet crimping and spot crimping. For example, when installing rivet crimping in this embodiment, holes for the rivet to pass through are provided in advance on the other side of the busbar connection part 21 where the crimping part 3 will be installed, and on one side of the busbar body 22. By inserting the rivet into both through holes, the tip of the rivet is crimped as shown in Figure 3. When installing spot crimping, the other side of the busbar connection part 21 to which the crimping part will be attached and one side of the busbar body 22 are brought into contact. The position for installing the crimping part 3 is determined at the contact point, and the part where the crimping part 3 will be installed is compressed using a crimping machine. By compressing, the other side of the busbar connection part 21 and one side of the busbar body part 22 are crimped as shown in Figure 4. The shape of the other side of the busbar connection part 21 and one side of the busbar body part 22 when installing the crimping part 3 may be changed depending on the type of crimping part 3 actually used. Furthermore, various known crimping structures may be used as the crimping portion 3. For example, as shown in Patent Document 1, a projection may be provided on one of the busbar connection portion 21 and the busbar body portion 22, and a through hole may be provided on the other of the busbar connection portion 21 and the busbar body portion 22, and after the projection is inserted into the through hole, the tip of the projection may be crimped.

[0019] As described above, one side of the busbar body 22 abuts against the other side of the busbar connection 21, and a connection hole 22a is formed on the other side. One side of the busbar body 22 abuts against the other side of the busbar connection 21 and is fixed by the crimping portion 3. Therefore, a processing area for installing the crimping portion 3 is provided on the surface of the tip of one side of the busbar body 22. In this embodiment 1, since the busbar body 22 is formed in an L shape, the other side of the busbar body 22 protrudes to one side X1 in the first direction. It is assumed that screws or bolts will be fitted into the connection hole 22a on the other side of the busbar body 22. Furthermore, the shape of the busbar body 22 and the busbar connection part 21 can be freely changed in relation to the output destination.

[0020] 2. Embodiment 2 The power converter according to Embodiment 2 will be described with reference to the drawings. The same components as those in Embodiment 1 will not be described. The basic configuration of the power converter according to this embodiment is the same as that of Embodiment 1, except that the configuration of the crimping portion 3 is slightly different. Figure 5 is a perspective view showing the configuration of the power converter according to Embodiment 2.

[0021] In this embodiment, the busbar connection portion 21 and the busbar body portion 22 are joined by two or more crimping portions 3. This configuration makes it possible to improve the strength of the crimping joint between the busbar connection portion 21 and the busbar body portion 22.

[0022] <Busbar connection section> The other side of the busbar connector 21 abuts against the busbar body 22 and is fixed by the crimping portion 3. In this example, the other side of the busbar connector 21 is formed in a plate shape so that it can be crimped. In the busbar connector 21 shown in Figure 5, two crimping portions 3 are installed along a direction perpendicular to the extension direction of the busbar connector 21 (in this example, one side Y1 of the second direction).

[0023] <Bus bar main body> One side of the busbar body 22 is formed in a plate shape in this example, as it is positioned in contact with the busbar connection 21, similar to Embodiment 1, and a crimping portion 3 is installed therein. In this embodiment, there are two or more holes at positions where it connects with the busbar connection 21. As described above, in the busbar body 22 shown in Figure 5, two crimping portions 3 are installed along a direction perpendicular to the extension direction of the busbar body 22 (in this example, one side Y1 of the second direction). One side of the busbar body 22 is deformed according to the type of crimping portion 3, similar to the other side of the busbar connection 21.

[0024] 3. Embodiment 3 The power converter according to Embodiment 3 will be described with reference to the drawings. The same components as those in Embodiment 1 will not be described. The basic configuration of the power converter according to this embodiment is the same as that of Embodiment 1, but the configuration of the crimping portion 3 is slightly different. Figure 6 is a perspective view showing the configuration of the power converter according to Embodiment 3.

[0025] In this embodiment, the crimped portion 3 is covered with a resin molding material 3a.

[0026] <Busbar connection section> The other side of the busbar connection portion 21 abuts against the busbar body portion 22 and is fixed by the crimping portion 3. In this example, the other side of the busbar connection portion 21 is formed in a plate shape so that it can be crimped. In this embodiment, as shown in Figure 6, the resin molded material 3a is formed to cover the crimping portion 3. The crimping portion 3 may be installed in one place as in Embodiment 1, or in two or more places as in Embodiment 2.

[0027] <Bus bar main body> One side of the busbar body 22 is formed in a plate shape in this example, as it is positioned in contact with the busbar connection 21, similar to Embodiment 1, and a crimping portion 3 is installed therein. In this embodiment, as shown in Figure 6, a resin molding material 3a is formed to cover the crimping portion 3. The crimping portion 3 may be installed in one place, as in Embodiment 1, or in two or more places, as in Embodiment 2.

[0028] <Resin molding materials> As described above, in Embodiment 3, the crimped portion 3 that connects the busbar connection portion 21 and the busbar body portion 22 is covered with a resin molding material 3a. With this configuration, moisture can be prevented from entering the crimped portion 3 by being covered with the resin molding material 3a, thereby preventing corrosion of the crimped portion 3. The resin molding material 3a is formed to cover at least the entire crimped portion 3 of the busbar connection portion 21 and the busbar body portion 22. A low-hygroscopic material and a moisture-resistant resin are used for the resin molding material 3a.

[0029] In this embodiment, the resin molding material 3a is formed in a cylindrical shape that seals the area around the crimping portion 3 and the busbar connection portion 21 and busbar body portion 22 where the crimping portion 3 is provided. With this configuration, moisture can be prevented from entering the crimping portion 3 and the joint surface of the busbar connection portion 21 and busbar body portion 22, thereby preventing corrosion of the crimping portion 3 and the joint surface.

[0030] 4. Embodiment 4 A power converter according to Embodiment 4 will be described with reference to the drawings. The same components as those in Embodiment 1 will not be described. The basic configuration of the power converter according to this embodiment is the same as that of Embodiment 1, except that the configuration of the crimping portion 3 is slightly different. Figure 7 is a perspective view showing the configuration of the power converter according to Embodiment 4.

[0031] In this embodiment, the crimped portion 3 is covered with a corrosion-resistant sealing material 3b.

[0032] <Busbar connection section> The other side of the busbar connection portion 21 abuts against the busbar body portion 22 and is fixed by the crimping portion 3. In this example, the other side of the busbar connection portion 21 is formed in a plate shape so that it can be crimped. In this embodiment, as shown in Figure 7, a corrosion-resistant sealing material 3b is formed to cover the crimping portion 3. The crimping portion 3 may be installed in one place as in Embodiment 1, or in two or more places as in Embodiment 2.

[0033] <Bus bar main body> One side of the busbar body 22 is formed in a plate shape in this example, as it is positioned in contact with the busbar connection 21, similar to Embodiment 1, and a crimping portion 3 is installed therein. In this embodiment, as shown in Figure 7, a corrosion-resistant sealing material 3b is formed to cover the crimping portion 3. The crimping portion 3 may be installed in one location, as in Embodiment 1, or in two or more locations, as in Embodiment 2.

[0034] <Corrosion-resistant sealant> As described above, in Embodiment 4, the crimped portion 3 that connects the busbar connection portion 21 and the busbar body 22 is covered with a corrosion-resistant sealant 3b. With this configuration, moisture can be prevented from entering the crimped portion 3, and corrosion of the crimped portion 3 can be prevented. The corrosion-resistant sealant 3b is formed to cover at least the entire crimped portion 3. The corrosion-resistant sealant 3b is made of a material with excellent heat resistance and insulation properties, such as silicone or epoxy resin.

[0035] In this embodiment, the crimped portion 3, and the areas surrounding the busbar connection portion 21 and busbar body portion 22 where the crimped portion 3 is provided, are covered with a corrosion-resistant sealant 3b. This structure prevents moisture from entering the crimped portion 3 and the joint surfaces of the busbar connection portion 21 and busbar body portion 22. By preventing moisture from entering, corrosion of the metal of the crimped portion 3, busbar body portion 22, and busbar connection portion 21 can be prevented, similar to embodiment 3.

[0036] 5. Embodiment 5 A power converter according to Embodiment 5 will be described with reference to the drawings. The same components as those in Embodiment 1 will not be described. The basic configuration of the power converter according to this embodiment is the same as that of Embodiment 1, except that the configuration of the crimping portion 3 is slightly different. Figure 8 is a perspective view showing the configuration of the power converter according to Embodiment 5.

[0037] In this embodiment, the surface of the crimped portion 3 is plated 3c.

[0038] <Busbar connection section> The other side of the busbar connection portion 21 abuts against the busbar body portion 22 and is fixed by the crimp portion 3. In this example, the other side of the busbar connection portion 21 is formed in a plate shape so that it can be crimped. In this embodiment, as shown in Figure 8, a plating process 3c is formed to cover the crimp portion 3. The crimp portion 3 may be installed in one place as in Embodiment 1, or in two or more places as in Embodiment 2.

[0039] <Bus bar main body> One side of the busbar body 22 is formed in a plate shape in this example, as it is positioned in contact with the busbar connection 21, similar to Embodiment 1, and a crimping portion 3 is installed therein. In this embodiment, as shown in Figure 7, a plating process 3c is formed to cover the crimping portion 3. The crimping portion 3 may be installed in one place, as in Embodiment 1, or in two or more places, as in Embodiment 2.

[0040] <Plating> As described above, in Embodiment 4, the surface of the crimped portion 3 that connects the busbar connection portion 21 and the busbar body 22 is plated. This configuration prevents moisture from entering the crimped portion 3 and prevents corrosion of the crimped portion 3. The corrosion-resistant sealant is formed to cover at least the entire crimped portion 3. A material with excellent corrosion resistance, such as nickel plating, is selected for the plating 3c.

[0041] In this embodiment, the surface of the crimped portion 3, as well as the surfaces of the busbar connection portion 21 and busbar body portion 22 on which the crimped portion 3 is provided, are covered by plating 3c. This structure prevents moisture from entering the joint surface of the crimped portion 3. By preventing moisture from entering, corrosion of the metal of the crimped portion 3, busbar body portion 22, and busbar connection portion 21 can be prevented, similar to embodiment 3.

[0042] 6. Embodiment 6 A power converter according to Embodiment 6 will be described with reference to the drawings. The same components as those in Embodiment 1 will not be described. The basic configuration of the power converter according to this embodiment is the same as that of Embodiment 1, but the configuration of the busbar body 22 and the busbar connection 21 differs in some respects. Figure 9 is a perspective view of the busbar 2 of a comparative example according to Embodiment 6. Figure 10 is a perspective view showing the configuration of the power converter according to Embodiment 6.

[0043] In this embodiment, the busbar body portion 22 has multiple branching portions that divide the current into multiple parts, and the busbar connection portion 21 and the assembly portion of the multiple branching portions are joined by a crimping portion 3. In this embodiment, the direction in which the portion having the connection hole 22a extends from the branching portion through five bends is defined as one side Z1 of the first direction, and the opposite side of one side Z1 of the first direction is defined as the other side Z2 of the first direction.

[0044] <Bus bar> As shown in Figure 9, the comparative example's branch busbar 2a is formed in a T-shape, and the entire branch busbar 2a is made entirely of copper. The tip of the branch source of the branch busbar 2a has a flat surface that connects to the power module's main terminal 1, and the main terminal 1 and the busbar connection surface 21a are in contact and welded together. Each of the two branch tips of the branch busbar 2a has a connection hole 22a into which screws, connection terminals, etc., are inserted, and current is distributed to each circuit and device.

[0045] In the comparative example, the entire branch busbar 2a is formed from copper. Shapes like the branch busbar 2a result in poor yield when stamped out with a press. This poor yield leads to a large amount of waste material, and because the entire structure is made of copper, it results in high costs.

[0046] In this embodiment, the branching source portion 22b of the branching busbar 2a shown in the comparative example is divided into a busbar connection portion 21, and the two branching portions are divided into a busbar body portion 22. The busbar body portion 22 has both ends extending in two directions, similar to the branching busbar 2a shown in the comparative example. The material of the busbar connection portion 21 includes copper, and the material of the busbar body portion 22 includes aluminum. For example, the busbar connection portion 21 may be made of copper or a copper alloy, and the busbar body portion 22 may be made of aluminum or an aluminum alloy.

[0047] <Busbar connection section> The busbar connector 21 is a connecting member that connects the main terminal 1 described above to the busbar body 22, which will be described later. One side of the busbar connector 21 abuts against the main terminal 1, and the other side abuts against the busbar body 22. One side of the busbar connector 21 has a flat surface because it abuts against the main terminal 1. The other side of the busbar connector 21 abuts against the busbar body 22 and is fixed by crimping. In this example, the other side of the busbar connector 21 is formed in a plate shape so that it can abut against the busbar body 22 and be crimped.

[0048] <Bus bar main body> The busbar body 22 extends in two directions from the crimped portion 3. Connection holes 22a are provided at both ends of the busbar body 22, allowing electricity to be transmitted to multiple locations. The busbar body 22 may have three or more branches. Furthermore, the shape of each branch may be arbitrary.

[0049] While this disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but are applicable individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are envisioned within the scope of the art disclosed in this disclosure. For example, these include modifying, adding or omitting at least one component, or even extracting at least one component and combining it with a component from another embodiment. [Explanation of symbols]

[0050] 1 Main terminal, 2 Busbar, 2a Branch busbar, 3 Crimping part, 3a Resin molding material, 3b Corrosion-resistant sealant, 3c Plating, 21 Busbar connection part, 21a Busbar connection surface, 22 Busbar body, 22a Connection hole, 22b Branch source part, 100 Power module

Claims

1. A power module having a main terminal containing copper as a material, The busbar body is made of aluminum, It includes a busbar connector made of copper, The main terminal and the busbar connection portion are welded together. A power conversion device in which the busbar connection portion and the busbar body portion are joined by a crimping portion.

2. The power conversion device according to claim 1, wherein the busbar connection portion and the busbar body portion are joined by two or more crimping portions.

3. The power conversion device according to claim 1 or 2, wherein the crimped portion is covered with a resin molding material.

4. The crimped portion is covered with a corrosion-resistant sealing material, as described in claim 1 or 2, for the power conversion device.

5. The power conversion device according to claim 1 or 2, wherein the surface of the crimped portion is plated.

6. The power conversion device according to claim 1 or 2, wherein the crimped portion is a crimped portion made by spot crimping or rivet crimping.

7. The busbar body has multiple branching sections that divide the current into multiple parts. The power conversion device according to claim 1 or 2, wherein the busbar connection portion and the assembly portion of the plurality of branch portions are joined by a crimping portion.

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