WO2019234467A1

WO2019234467A1 - Power converter

Info

Publication number: WO2019234467A1
Application number: PCT/IB2018/000741
Authority: WO
Inventors: 伸也駒﨑
Original assignee: 日産自動車株式会社; ルノーエス、ア、エス
Priority date: 2018-06-08
Filing date: 2018-06-08
Publication date: 2019-12-12

Abstract

A power converter (10) is provided with: a switching element (200) for converting direct-current electric power to alternating-current electric power; a capacitor module (100) for smoothing the voltage to be input to the switching element (200); a conductor part (103a) for electrically connecting the capacitor module (100) and the switching element (200); a conductor member that includes a branching part (107b) formed by branching from the conductor part (103a); and a cooler (300) that is thermally connected to the branching part (107b).

Description

Power converter

The present invention relates to a power conversion device.

Conventionally, a method of cooling a power converter is known (Patent Document 1). In the invention described in Patent Document 1, a capacitor and a switching element are connected by a bus bar, and a cooler is connected to the bus bar.

JP 2017-93005 A

Usually, a bus bar connecting a capacitor and a switching element is required to shorten the bus bar length in order to reduce its inductance component, but a cooler is connected to the bus bar as in the invention described in Patent Document 1. In order to do this, it is necessary to lengthen the bus bar. However, when the bus bar is lengthened, the inductance component increases, and thus the surge voltage may increase.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power converter that has cooling performance and does not increase the length of the bus bar.

A power conversion device according to one embodiment of the present invention includes a switching element, a capacitor module that smoothes a voltage input to the switching element, a conductive portion that electrically connects the capacitor module and the switching element, and a branch from the conductive portion. And a cooler that is thermally connected to the branch portion.

According to the present invention, a power converter that has cooling performance and does not increase the length of the bus bar is realized.

FIG. 1 is a schematic configuration diagram of a power conversion device according to the first embodiment of the present invention. FIG. 2 is a schematic configuration diagram of the capacitor module according to the first embodiment of the present invention. FIG. 3 is a diagram for explaining a connection relationship between the capacitor module and the switching element according to the first embodiment of the present invention. FIG. 4 is another diagram illustrating the connection relationship between the capacitor module and the switching element according to the first embodiment of the present invention. FIG. 5 is a schematic configuration diagram of the cooler according to the first embodiment of the present invention. FIG. 6 is a schematic configuration diagram of a power conversion device according to the second embodiment of the present invention. FIG. 7 is a schematic configuration diagram of a power conversion device according to the third embodiment of the present invention. FIG. 8 is a schematic configuration diagram of a power conversion device according to the fourth embodiment of the present invention. FIG. 9 is a schematic configuration diagram of a power conversion device according to the fifth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same portions are denoted by the same reference numerals, and description thereof is omitted.

(First embodiment)
With reference to FIG. 1, the power converter device 10 which concerns on 1st Embodiment is demonstrated. As shown in FIG. 1, the power conversion device 10 includes a DC power supply 20, a capacitor module 100, and a switching element 200.

The switching element 200 converts DC power input from the DC power supply 20 into AC power by on / off control, and supplies the AC power to the motor 21.

The capacitor module 100 is formed between the DC power supply 20 and the switching element 200. Capacitor module 100 smoothes the voltage between DC power supply 20 and switching element 200. Thereby, voltage and current pulsations of the power supply bus due to switching are suppressed.

The bus bar 103 (conductive portion) is formed between the capacitor module 100 and the switching element 200. In other words, the bus bar 103 connects the capacitor module 100 and the switching element 200. The bus bar 103 is made of a conductive member (for example, copper).

Next, the capacitor module 100 will be described with reference to FIG. In the present embodiment, the capacitor module 100 is described as a film capacitor, but the present invention is not limited to this.

2, the capacitor module 100 includes a capacitor element 101, a first electrode 102a, a second electrode 102b, a resin member 105, and a case 104.

The first electrode 102a and the second electrode 102b are electrically connected to the capacitor element 101 and are formed to face each other. The first electrode 102 a is connected to the upper surface of the capacitor element 101, and the second electrode 102 b is connected to the lower surface of the capacitor element 101. In this embodiment, for convenience of explanation, the capacitor element 101, the first electrode 102a, and the second electrode 102b will be described separately. However, the capacitor including the capacitor element 101, the first electrode 102a, and the second electrode 102b will be described. It may be expressed as an element. A first bus bar 103a (first conductive portion) is connected to the first electrode 102a. Similarly, the second bus bar 103b (second conductive portion) is connected to the second electrode 102b.

Part of the first bus bar 103 a and the second bus bar 103 b is drawn out of the case 104. In addition, an insulating member 106 is formed between the first bus bar 103a and the second bus bar 103b in a region where the first bus bar 103a and the second bus bar 103b are close to each other.

The case 104 houses the capacitor element 101, the first electrode 102a, and the second electrode 102b. The case 104 is made of aluminum, for example. The case 104 is filled with a resin member 105. That is, in the case 104, the capacitor element 101, the first electrode 102a, the second electrode 102b, the first bus bar 103a, and the second bus bar 103b are fixed by the resin member 105.

Next, the connection relationship between the capacitor module 100 and the switching element 200 will be described with reference to FIG. As shown in FIG. 3, the first bus bar 103 a pulled out from the case 104 is connected to the terminal block 202. The terminal block 202 is connected to a case 201 that houses the switching element 200. Similarly, the second bus bar 103 b pulled out from the case 104 is also connected to the terminal block 203. The first bus bar 103a and the second bus bar 103b drawn from the case 104 are configured to be short in order to reduce inductance. The first bus bar 103 a and the second bus bar 103 b pulled out from the case 104 are arranged in the vicinity of the switching element 200 so as to face each other with the insulating member 106 interposed therebetween.

As shown in FIG. 3, the first bus bar 103a includes a first branch part 107a (branch part) formed by branching from the first bus bar 103a. Therefore, the 1st branch part 107a is also comprised with the member (for example, copper) which has electroconductivity similarly to the 1st bus-bar 103a. Thus, in this embodiment, the 1st bus-bar 103a and the 1st branch part 107a are one conductive member. The first bus bar 103a electrically connects the capacitor module 100 and the switching element 200. The cooler 300 is connected to the first branch portion 107a. The first branch portion 107a does not constitute an electrical connection, but constitutes a thermal connection. The first branch portion 107 a is cooled by the cooler 300. Since the first branch portion 107a and the first bus bar 103a are made of copper having high thermal conductivity, the first bus bar 103a is also cooled by cooling the first branch portion 107a. Thereby, the capacitor module 100 connected to the first bus bar 103a is also cooled.

Similarly, the second bus bar 103b includes a second branch portion 107b formed by branching from the second bus bar 103b. Therefore, the 2nd branch part 107b is also comprised with the member (for example, copper) which has electroconductivity similarly to the 2nd bus-bar 103b. The second bus bar 103b and the second branch portion 107b are also one conductive member. The second bus bar 103b electrically connects the capacitor module 100 and the switching element 200. The cooler 400 is connected to the second branch portion 107b. The second branch 107b does not constitute an electrical connection, but constitutes a thermal connection. The second branch portion 107b is cooled by the cooler 400. Since the second branch part 107b and the second bus bar 103b are made of copper having high thermal conductivity, the second bus bar 103b is also cooled by cooling the second branch part 107b. Thereby, the capacitor module 100 connected to the second bus bar 103b is also cooled.

As described above, the cooler 300 (cooler 400) is thermally connected to the first branch portion 107a (second branch portion 107b) formed by branching from the first bus bar 103a (second bus bar 103b). The Thereby, the 1st branch part 107a (2nd branch part 107b) is cooled, and the capacitor module 100 is also cooled. The cooler 300 (cooler 400) is not connected to the first bus bar 103a (second bus bar 103b), but is connected to the first branch portion 107a (second branch portion 107b). Therefore, it is not necessary to increase the length of the bus bar as in the prior art. Thereby, the power converter device 10 having a cooling performance and a small inductance component of the bus bar is realized.

In FIG. 3, there are two cooling points, but the present invention is not limited to this. For example, the number of cooling points may be one, or three or more. As shown in FIG. 4, only one cooler 300 may be connected to the first branch portion 107a. Moreover, in FIG. 3, although the 1st branch part 107a is branched outside the case 104, it is not limited to this. For example, as shown in FIG. 4, the first branch portion 107 a may be branched inside the case 104.

Next, an example of the cooler 300 will be described with reference to FIG. The cooler 300 is not limited to that shown in FIG.

As shown in FIG. 5, the cooler 300 includes a metal member 301, an insulating member 302, cooling water 303, and a water jacket 304. The side surface and the bottom surface of the metal member 301 are covered with an insulating member 302.

The first branch portion 107a is made of a conductive member (for example, copper) like the first bus bar 103a, and thus has conductivity. The cooler 300 is also composed of a conductive member (metal member 301). Since the first branch portion 107a is connected to the metal member 301, the current flowing through the first branch portion 107a may flow to the case ground through the metal member 301, the cooling water 303, and the water jacket 304. In order to prevent the current flowing through the first branch portion 107a from flowing into the case ground, it is necessary to insulate the first branch portion 107a from the cooling water 303. In the invention described in Patent Document 1 described above, insulation is realized by using an electrically insulating heat conductive material at the contact portion between the cooler and the bus bar. However, the electrical insulating heat conductive material is generally weak in strength and may be destroyed when fixed with bolts. Further, if the cooler and the bus bar are merely brought into contact without using bolts, the contact thermal resistance is high and the cooling effect may not be obtained.

Therefore, in the present embodiment, as shown in FIG. 5, the first branch portion 107 a is thermally connected to the metal member 301. A portion of the metal member 301 excluding the surface in contact with the first branch portion 107 a is covered with the insulating member 302. More specifically, the side surface and the bottom surface of the metal member 301 other than the top surface that is in contact with the first branch portion 107 a are covered with the insulating member 302. Thereby, the 1st branch part 107a and the cooler 300 have sufficient connection strength. Moreover, the 1st branch part 107a and the cooling water 303 are insulated. Thereby, the 1st branch part 107a is cooled efficiently. Note that the water jacket 304 may be used as an insulating member. In FIG. 5, the second branch 107b is omitted.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG.

It is known that the capacitor element 101 repeatedly expands and contracts in the horizontal direction perpendicular to the vertical direction by the Coulomb force generated by the switching current, and vibrates the capacitor module 100.

Therefore, as shown in FIG. 6, the first branch portion 107a is formed to branch from the first bus bar 103a between the first electrode 102a and the second electrode 102b in the vertical direction. Further, the first branch portion 107 a is pulled out of the case 104. Similarly, the second branch portion 107b is formed to branch from the second bus bar 103b between the first electrode 102a and the second electrode 102b in the vertical direction. Further, the second branch portion 107 b is pulled out of the case 104. Further, the first branch portion 107a and the second branch portion 107b are formed to be parallel to the first electrode 102a and the second electrode 102b in the horizontal direction. Thereby, the rigidity with respect to expansion and contraction is increased in the horizontal direction, and vibration of the capacitor module 100 is suppressed.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG.

As shown in FIG. 7,

coolers

300 and 500 are connected to the upper surface and the lower surface of the first branch portion 107a, respectively. Thereby, the contact area of the 1st branch part 107a and a cooler increases, and cooling performance improves.

There is a method of using one cooler as a method of increasing the contact area, but there are the following problems. That is, when the contact area is increased using one cooler, the projected area of the power conversion device is increased. On the other hand, in the present embodiment, as shown in FIG. 7, the contact area is increased without enlarging the projected area by connecting the two

coolers

300 and 500 to the first branch portion 107a in the vertical direction. Can be increased. In addition, the

coolers

300 and 500 are pressed against the first branch portion 107a from the upper surface and the lower surface, thereby improving the contact between the two

coolers

300 and 500 and the first branch portion 107a and reducing the contact thermal resistance. Thereby, cooling performance improves. In the example illustrated in FIG. 7, it is described that the

coolers

300 and 500 are connected to the upper surface and the lower surface of the first branch portion 107a, but the present invention is not limited to this. A cooler may be connected to each of at least two surfaces of the first branch portion 107a. In FIG. 7, the second branch 107b is omitted.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG.

Generally, the capacitor element 101 has a larger equivalent series resistance than the bus bar 103 (the first bus bar 103a and the second bus bar 103b). For this reason, when the switching current is large, the heat generation of the capacitor element 101 increases. Further, when the direct current is large, the heat generation of the bus bar 103 (first bus bar 103a, second bus bar 103b) increases.

As shown in FIG. 8, the maximum heat generating portion 600 of the capacitor element 101 is determined by the heat generated by the capacitor element 101 and the heat generated from the bus bar 103 (first bus bar 103a, second bus bar 103b). In the fourth embodiment, the first branch portion 107 a is formed in the vicinity of the maximum heat generating portion 600 and is drawn out of the case 104 from the vicinity of the maximum heat generating portion 600. Thus, the capacitor module 100 is efficiently cooled by cooling the first branch portion 107a drawn out of the case 104 from the position determined based on the maximum heat generating portion 600. The maximum heat generating portion 600 refers to a portion that generates the most heat in the capacitor module 100.

(Fifth embodiment)
Next, a fifth embodiment will be described with reference to FIG.

When the bus bar 103 (first bus bar 103a, second bus bar 103b) and the switching element 200 are fastened with bolts, the bus bar 103 (first bus bar 103a, second bus bar 103b) has contact electrical resistance at the connection point with the switching element 200. It generates the most heat. Therefore, it is conceivable to cool the vicinity of the connection point between the bus bar 103 (the first bus bar 103a and the second bus bar 103b) and the switching element 200. However, when the first bus bar 103a and the first branch portion 107a are in close contact with each other, the cooling performance may be reduced due to the dimensional tolerance between the switching element 200 and the cooler 300. More specifically, the contact property on the connection surface between the first bus bar 103a and the switching element 200 and the connection surface between the first branch portion 107a and the cooler 300 is deteriorated, and the cooling performance may be deteriorated.

Therefore, in this embodiment, as shown in FIG. 9, a slit 108 a is formed between the first bus bar 103 a and the first branch portion 107 a in the vicinity of the cooler 300. Further, as shown in FIG. 9, the first branch portion 107 a is formed to branch from the first bus bar 103 a outside the case 104. Similarly, a slit 108b is formed between the second bus bar 103b and the second branch portion 107b in the vicinity of the cooler 400. Further, the second branch portion 107 b is formed to branch from the second bus bar 103 b outside the case 104. Thereby, in the connection surface of the 1st bus-bar 103a and the switching element 200, and the connection surface of the 1st branch part 107a and the cooler 300, the deterioration of the contact property by a dimensional tolerance is suppressed. In the example shown in FIG. 9, the

slits

108a and 108b are formed in a direction perpendicular to the horizontal direction, but the present invention is not limited to this. The

slits

108a and 108b may be formed in the horizontal direction (see FIG. 3). The

slits

108 a and 108 b are formed outside the case 104. The slit 108a (108b) may be formed so as to have a region overlapping with the cooler 300 (cooler 400) when the power converter 10 is viewed from above.

As described above, the embodiments of the present invention have been described. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

DESCRIPTION OF SYMBOLS 10 Power converter 20 DC power supply 21 Motor 100 Capacitor module 101 Capacitor element 102a 1st electrode 102b 2nd electrode 103 Bus bar 103a 1st bus bar 103b

2nd bus bar

104, 201 Case 105 Resin member 106 Insulating member 107a 1st branch part 107b 1st Two

branch portions

108a, 108b Slit 200

Switching elements

202, 203 Terminal blocks 300, 400, 500 Cooler 301 Metal member 302 Insulating member 303 Cooling water 304 Water jacket

Claims

A switching element that converts DC power to AC power;
A capacitor module for smoothing a voltage input to the switching element;
A conductive member that includes a conductive portion that electrically connects the capacitor module and the switching element; and a branch portion that is formed by branching from the conductive portion;
And a cooler thermally connected to the branch portion.
The capacitor module is
A capacitor element;
A first electrode and a second electrode which are electrically connected to the capacitor element and formed to face each other;
A case for accommodating the capacitor element, the first electrode, and the second electrode;
The conductive part is
A first conductive part connected to the first electrode; and a second conductive part connected to the second electrode;
The branch portion is
A first branch portion formed by branching from the first conductive portion between the first electrode and the second electrode in a direction perpendicular to the ground;
A second branch part formed by branching from the second conductive part between the first electrode and the second electrode in the vertical direction,
The first conductive portion, the second conductive portion, the first branch portion, and the second branch portion are pulled out from the case,
2. The electric power according to claim 1, wherein the first branch portion, the second branch portion, the first electrode, and the second electrode are parallel in a horizontal direction perpendicular to the vertical direction. Conversion device.
The cooler is
A metal member;
Including an insulating member,
The branch portion is thermally connected to the metal member,
The power converter according to claim 1, wherein a portion of the metal member excluding a surface in contact with the branch portion is covered with the insulating member.
The power converter according to claim 1 or 3, wherein the cooler is connected to each of at least two surfaces of the branch portion.
The capacitor module is
A capacitor element;
A first electrode and a second electrode which are electrically connected to the capacitor element and formed to face each other;
Containing the capacitor element, the first electrode, and the second electrode,
5. The power conversion device according to claim 1, wherein the branch portion is drawn out of the case from a position determined based on a most heat-generating part in the capacitor module.
The capacitor module is
A capacitor element;
A first electrode and a second electrode which are electrically connected to the capacitor element and formed to face each other;
Containing the capacitor element, the first electrode, and the second electrode,
The branch portion is formed to branch from the conductive portion outside the case,
5. The power conversion device according to claim 1, wherein a slit is formed between the branch portion and the conductive portion outside the case. 6.