阅读说明：本技术 功率转换装置 (Power conversion device ) 是由 玉山敦史 于 2021-05-27 设计创作，主要内容包括：本发明提供一种能够保护电容器元件避免温度升高的功率转换装置。包括：半导体模块、电容器模块和冷却器,正极侧汇流条和负极侧汇流条中的一个的一端连接到与电容器壳体的散热壁相对地配置的电容器元件的第一端子和第二端子中的一个,正极侧汇流条和负极侧汇流条中的另一个的一端连接到与电容器壳体的相对壁相对地配置的电容器元件的第一端子和第二端子中的另一个,包括散热用金属体,该散热用金属体具有通过绝缘构件与正极侧汇流条和负极侧汇流条中的另一个的一端和另一端之间的中间连接部分相对并热连接的部分,并且该散热用金属体热连接到冷却器。(The invention provides a power conversion device capable of protecting a capacitor element from temperature rise. The method comprises the following steps: a semiconductor module, a capacitor module, and a cooler, one end of one of a positive-side bus bar and a negative-side bus bar being connected to one of a first terminal and a second terminal of a capacitor element disposed opposite a heat dissipation wall of a capacitor case, one end of the other of the positive-side bus bar and the negative-side bus bar being connected to the other of the first terminal and the second terminal of the capacitor element disposed opposite the opposite wall of the capacitor case, includes a heat-dissipating metal body having a portion that is opposed to and thermally connected to an intermediate connection portion between the one end and the other end of the other of the positive-side bus bar and the negative-side bus bar through an insulating member, and the heat-dissipating metal body is thermally connected to the cooler.)

1. A power conversion apparatus, comprising:

a semiconductor module having a semiconductor element, a positive-side module bus bar having one end electrically connected to a first terminal of the semiconductor element directly or indirectly and the other end extending to the outside from a protective member surrounding the semiconductor element, and a negative-side module bus bar having one end electrically connected to a second terminal of the semiconductor element directly or indirectly and the other end extending to the outside from the protective member;

a capacitor module having a capacitor element, a capacitor case that accommodates the capacitor element by a filling resin, a positive-side bus bar having one end electrically connected to the capacitor element and the other end extending from the capacitor case to the outside and electrically connected to the other end of the positive-side module bus bar, and a negative-side bus bar having one end electrically connected to the capacitor element and the other end extending from the capacitor case to the outside and electrically connected to the other end of the negative-side module bus bar; and

a cooler thermally connected to the capacitor module and the semiconductor module,

one of the first terminal and the second terminal of the capacitor element is arranged opposite to a wall of the capacitor case thermally connected to the cooler, that is, a heat dissipation wall, and the other of the first terminal and the second terminal of the capacitor element is arranged opposite to a wall of the capacitor case opposite to the heat dissipation wall, that is, an opposite wall,

one end of one of the positive-side bus bar and the negative-side bus bar is connected to one of a first terminal and a second terminal of the capacitor element disposed opposite the heat dissipation wall inside the capacitor case,

one end of the other of the positive-side bus bar and the negative-side bus bar is connected to the other of the first terminal and the second terminal of the capacitor element disposed opposite the opposing wall inside the capacitor case,

the power conversion device includes a heat-dissipating metal body that has a plate-like portion that is opposed to and thermally connected to a plate-like intermediate connection portion between one end and the other end of the other of the positive-side bus bar and the negative-side bus bar via an insulating member, and that is thermally connected to the cooler.

2. The power conversion apparatus according to claim 1,

the polarity of one of the positive-side bus bar and the negative-side bus bar disposed on the heat radiation wall side of the capacitor case inside the capacitor case is the polarity of the one of the positive-side module bus bar and the negative-side module bus bar having a longer wiring length inside the semiconductor module.

3. The power conversion apparatus according to claim 1,

the polarity of one of the positive-side bus bar and the negative-side bus bar disposed on the heat radiation wall side of the capacitor case inside the capacitor case is the polarity of the bus bar that is directly electrically connected to the semiconductor element inside the semiconductor module, of the positive-side module bus bar and the negative-side module bus bar.

4. The power conversion apparatus according to any one of claims 1 to 3,

the plate-shaped portion of the heat radiating metal body and the intermediate connection portion are disposed inside the capacitor case.

5. The power conversion apparatus according to any one of claims 1 to 3,

the plate-shaped portion of the heat radiating metal body and the intermediate connection portion are disposed outside the capacitor case.

6. The power conversion apparatus according to any one of claims 1 to 5,

a coolant flow path that flows a coolant from one side of the cooler toward the other side of the cooler in a direction parallel to a surface of the cooler on the outside where the capacitor module and the semiconductor module are arranged,

the capacitor module is disposed on an outer surface of the cooler at an upstream portion of the refrigerant flow path, and the semiconductor module is disposed on an outer surface of the cooler at a downstream portion of the refrigerant flow path.

Technical Field

The present application relates to a power conversion apparatus.

Background

A plurality of power conversion devices are mounted on an electric vehicle using a motor as a drive source, such as an electric vehicle or a hybrid vehicle. As the power conversion device, there can be exemplified a charger for converting a commercial alternating-current power supply into a direct-current power supply and charging a high-voltage battery; a DC/DC converter for converting a direct current power source of the high voltage battery into a voltage (e.g., 12V) of a battery for auxiliary equipment; and an inverter for converting direct current from the battery into alternating current supplied to the motor, and the like.

A known power conversion apparatus includes a semiconductor module mounted with a switching element for performing power conversion; a cooler for cooling the semiconductor module; and a capacitor module having a capacitor element for smoothing the direct current voltage. Since the ripple current flows through the capacitor element, the capacitor element consumes power and generates heat. Further, since the capacitor element is connected to the semiconductor module by the bus bar, when the temperature of the semiconductor module becomes high, heat is transferred from the semiconductor module to the capacitor element through the bus bar, and the transferred heat causes the temperature of the capacitor element to become high as well. In particular, in a power conversion device with high output density, heat generation amount increases due to heat transfer to a bus bar connecting a semiconductor module and a capacitor element and joule heat of the bus bar. On the other hand, since it is desired to make the power conversion device smaller and lighter, it is difficult to enlarge the cross-sectional area of the bus bar to a cross-sectional area that is more than sufficient for heat generation. Therefore, the temperature increase of the bus bar becomes significant, and heat is transferred to the capacitor element, so that the temperature of the capacitor element increases. Since the increase in the temperature of the capacitor element shortens the life of the capacitor element, a countermeasure against the increase in the temperature of the capacitor element is a problem.

In order to suppress a temperature rise of the capacitor element, a structure for cooling the capacitor element provided in the power conversion device is disclosed (for example, see patent document 1). In the disclosed structure, the positive-side bus bar and the negative-side bus bar connected to the capacitor element and the semiconductor module are brought into contact with the heat dissipation member through the insulating material on the opposite faces to the connection faces of the two electrodes of the capacitor element. Since the heat generated by the metal layers constituting the two electrodes of the capacitor element is easily conducted to the heat dissipating member, the capacitor element can be efficiently cooled by dissipating the heat from the heat dissipating member.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2016-149907

Disclosure of Invention

Technical problem to be solved by the invention

In patent document 1, heat can be radiated from the vicinity of both the positive electrode side and the negative electrode side of the electrode surface of the capacitor element by the heat radiation member. However, particularly when the power conversion device has a high output, the heat generated from the semiconductor module connected to the capacitor element by the bus bar provided in the capacitor element becomes large. Further, the bus bars inside the semiconductor module and inside the capacitor module generate heat by joule heat. In the disclosed structure, since the heat received from the outside of the capacitor element and the cooling of the bus bar heat generation are insufficient, the temperature of the capacitor element mounted inside the device rises, and the capacitor element is thermally damaged. Specifically, although the temperature of the bus bar near the terminal block is increased by the heat transferred from the terminal block of the capacitor element to the bus bar provided in the capacitor and the joule heat generated in the bus bar, the capacitor element is disposed in the vicinity thereof and there is no heat countermeasure for the capacitor element, so that the capacitor element may be thermally damaged.

Therefore, an object of the present application is to obtain a power conversion device capable of protecting a capacitor element from a temperature increase.

Technical scheme for solving technical problem

The power conversion device disclosed in the present application includes: a semiconductor module including a semiconductor element, a positive-side module bus bar having one end electrically connected to a first terminal of the semiconductor element directly or indirectly and the other end extending to the outside from a protective member surrounding the semiconductor element, and a negative-side module bus bar having one end electrically connected to a second terminal of the semiconductor element directly or indirectly and the other end extending to the outside from the protective member; a capacitor module having a capacitor element, a capacitor case, a positive-side bus bar, and a negative-side bus bar, the capacitor case accommodating the capacitor element by a resin for filling, the positive-side bus bar having one end electrically connected to the capacitor element and the other end extending from the capacitor case to the outside and electrically connected to the other end of the positive-side module bus bar, the negative-side bus bar having one end electrically connected to the capacitor element and the other end extending from the capacitor case to the outside and electrically connected to the other end of the negative-side module bus bar; and a cooler thermally connected to the capacitor module and the semiconductor module, one of the first terminal and the second terminal of the capacitor element being disposed opposite a heat dissipation wall that is a wall of a capacitor case thermally connected to the cooler, the other of the first terminal and the second terminal of the capacitor element being disposed opposite an opposite wall that is an opposite wall of the capacitor case, one end of one of the positive-side bus bar and the negative-side bus bar being connected to one of the first terminal and the second terminal of the capacitor element disposed opposite the heat dissipation wall inside the capacitor case, one end of the other of the positive-side bus bar and the negative-side bus bar being connected to the other of the first terminal and the second terminal of the capacitor element disposed opposite the opposite wall inside the capacitor case, the power conversion device including a heat dissipation metal body, the heat-dissipating metal body has a plate-like portion that is opposed to and thermally connected to a plate-like intermediate connection portion between one end and the other end of the other of the positive-side bus bar and the negative-side bus bar via an insulating member, and is thermally connected to the cooler.

Effects of the invention

According to the power conversion device disclosed in the present application, the heat-dissipating metal body is included, the heat-dissipating metal body has the plate-like portion that is opposed to and thermally connected to the plate-like intermediate connection portion between the one end and the other end of the other of the positive-side bus bar and the negative-side bus bar through the insulating member, and the heat-dissipating metal body is thermally connected to the cooler, so the cooling performance of the other of the positive-side bus bar and the negative-side bus bar to which the other of the first terminal and the second terminal of the capacitor element arranged opposite to the opposed wall is connected can be improved, and the capacitor element can be protected from a temperature rise.

Drawings

Fig. 1 is a plan view schematically showing a power conversion device according to embodiment 1.

Fig. 2 is a main portion sectional view of the power conversion apparatus cut off at a sectional position a-a of fig. 1.

Fig. 3 is a main portion sectional view of the power conversion apparatus cut off at a section B-B position of fig. 2.

Fig. 4 is a main portion sectional view of another power conversion apparatus cut at a sectional position a-a of fig. 1.

Fig. 5 is a cross-sectional view showing an outline of the power conversion device according to embodiment 2.

Fig. 6 is a cross-sectional view showing an outline of a power conversion device according to embodiment 3.

Fig. 7 is a cross-sectional view showing an outline of the power conversion device according to embodiment 4.

Detailed Description

Hereinafter, a power conversion device according to an embodiment of the present application will be described with reference to the drawings. In the drawings, the same or corresponding members and portions are denoted by the same reference numerals and described.

Embodiment 1.

Fig. 1 is a plan view showing an outline of a power converter 100 according to embodiment 1, fig. 2 is a main part sectional view of the power converter 100 cut at a cross-sectional position a-a in fig. 1, fig. 3 is a main part sectional view of the power converter 100 cut at a cross-sectional position B-B in fig. 2, and fig. 4 is a main part sectional view of another power converter 100 cut at the same position as the cross-sectional position a-a in fig. 1. Fig. 1 is a diagram showing a part of the capacitor element 5 inside by removing a part of the capacitor case 6 and the positive-side bus bar 7a, fig. 2 and 4 are diagrams showing by omitting the inside of the semiconductor module 1c and the cooler 2, and fig. 3 is a diagram showing by omitting the inside of the cooler 2.

As shown in fig. 1, the power conversion device 100 includes a semiconductor module 1, a cooler 2, a capacitor module 3, and a heat dissipating metal body 4. The power conversion device 100 is a device that converts the power of the dc power smoothed by the capacitor module 3 by the semiconductor module 1 and outputs the converted dc power from the external terminal 18. The present embodiment shows a power conversion device 100 that outputs three-phase alternating current, and the semiconductor module 1 is configured by semiconductor modules 1a, 1b, and 1c corresponding to the respective phases. Fig. 1 does not show an input unit provided in the power conversion device 100.

< semiconductor Module 1>

The semiconductor modules 1a, 1b, 1c respectively include a semiconductor element 13 (not shown in fig. 1), a positive-side module bus bar 7b, and a negative-side module bus bar 8 b. One end of the positive-side module bus bar 7b is electrically connected to the first terminal of the semiconductor element 13 directly or indirectly, and the other end extends to the outside from the protective member 21 surrounding the semiconductor element 13. One end of the negative-side module bus bar 8b is electrically connected to the second terminal of the semiconductor element 13 directly or indirectly, and the other end extends from the protective member 21 to the outside. The components of the semiconductor module 1 such as the semiconductor element 13 are sealed with resin as the protective member 21, for example, but the protective member 21 is not limited thereto. The protective member 21 may be a case surrounding the semiconductor element 13 or the like.

< cooler 2>

The cooler 2 is thermally connected to the semiconductor module 1, the capacitor module 3, and the heat radiating metal body 4 through the outer cooling surface 2b, and cools the semiconductor module 1, the capacitor module 3, and the heat radiating metal body 4. The cooler 2 includes a refrigerant flow path 2a (not shown in fig. 1) through which a refrigerant flows inside the refrigerant flow path 2 a. The refrigerant as a fluid flows in a direction parallel to the outside cooling surface 2b from the refrigerant inlet 10 provided on one side of the cooler 2 toward the refrigerant outlet 11 provided on the other side. As the refrigerant, for example, water or a glycol liquid is used. The cooling surface 2b is cooled by the refrigerant. The cooler 2 is made of, for example, aluminum die casting.

< capacitor Module 3>

As shown in fig. 2, the capacitor module 3 includes a capacitor element 5 for smoothing direct current, a capacitor case 6 that accommodates the capacitor element 5 by a filling resin 9, a positive-side bus bar 7a, and a negative-side bus bar 8 a. The second terminal 5b of the capacitor element 5 is arranged to oppose a heat radiation wall 6a of the capacitor case 6 thermally connected to the cooler 2, and the first terminal 5a of the capacitor element 5 is arranged to oppose an opposing wall 6b of the capacitor case 6 opposing the heat radiation wall 6 a. In the present embodiment, the first terminal 5a is disposed so as to face the opposing wall 6b, and the second terminal 5b is disposed so as to face the heat radiation wall 6a, but the present invention is not limited to this, and the first terminal 5a may be disposed so as to face the heat radiation wall 6a, and the second terminal 5b may be disposed so as to face the opposing wall 6 b.

One end of the positive-side bus bar 7a is electrically connected to the capacitor element 5, and the other end extends from the capacitor case 6 to the outside and is electrically connected to the other end of the positive-side module bus bar 7 b. One end of the negative-side bus bar 8a is electrically connected to the capacitor element 5, and the other end extends from the capacitor case 6 to the outside and is electrically connected to the other end of the negative-side module bus bar 8 b. One end of one of the positive-side bus bar 7a and the negative-side bus bar 8a is connected to the second terminal 5b of the capacitor element 5 arranged opposite to the heat radiation wall 6a in the interior of the capacitor case 6, and one end of the other of the positive-side bus bar 7a and the negative-side bus bar 8a is connected to the first terminal 5a of the capacitor element 5 arranged opposite to the opposite wall 6b in the capacitor case 6. In the present embodiment, one end of the negative-side bus bar 8a is connected to the second terminal 5b, and one end of the positive-side bus bar 7a is connected to the first terminal 5a, but the present invention is not limited thereto.

As shown in fig. 1, the capacitor module 3 is fixed to the cooling surface 2b of the cooler 2 by a capacitor module fixing portion 14 provided in the capacitor case 6. The fixing method is, for example, a screw stopper, but is not limited thereto. As shown in fig. 2, in order to improve the cooling efficiency of the capacitor module 3, heat radiation grease 20 as a heat conductive member is disposed between the capacitor case 6 and the cooling surface 2 b. The heat conductive member is not limited to the heat dissipating grease 20, and may be, for example, a heat sink or a heat dissipating compound. The heat radiation grease 20 may be provided between the semiconductor module 1, the heat radiation metal body 4, and the cooling surface 2 b.

In order to connect the capacitor module 3 and the semiconductor module 1 with low wiring inductance, the capacitor module 3 and the semiconductor module 1 are disposed close to each other. Since the capacitor module 3 and the semiconductor module 1 are arranged close to each other and the capacitor module 3 and the semiconductor module 1 are connected with a low wiring inductance, it is possible to suppress occurrence of an unnecessary loss in the bus bar for connecting the capacitor module 3 and the semiconductor module 1. Since the occurrence of the loss is suppressed, heat generation caused by joule heat of the bus bar is suppressed, and the capacitor element 5 can be protected from temperature increase.

< Metal body for Heat radiation 4>

The heat dissipating metal body 4 has a plate-like portion 4b, and the plate-like portion 4b is a plate-like portion that is opposed to and thermally connected to a plate-like intermediate connecting portion 22 between one end and the other end of the other of the positive-side bus bar 7a and the negative-side bus bar 8a through an insulating member, i.e., the filling resin 9. The heat radiating metal body 4 is thermally connected to the cooling surface 2b of the cooler 2 via a connecting portion 4 a. Plate-shaped portion 4b of heat radiating metal body 4 and intermediate connecting portion 22 are disposed inside capacitor case 6.

With this configuration, the positive-side bus bar 7a connected to the capacitor element 5 on the side of the opposing wall 6b away from the cooling surface 2b of the cooler 2 can be cooled by the cooler 2 through the heat-radiating metal member 4. The heat generated at the portion of capacitor element 5 on the side of opposing wall 6b can also be cooled by heat dissipating metal body 4. Particularly when the power conversion device 100 has a high output density, although the positive-side bus bar 7a generates heat due to its own joule heat and receives heat from the semiconductor module 1, since the positive-side bus bar 7a can be cooled by the heat radiating metal body 4, a temperature increase of the capacitor element 5 due to the positive-side bus bar 7a can be prevented. Since the metal heat dissipating body 4 is disposed inside the capacitor case 6, a process of providing the metal heat dissipating body 4 to the power conversion device 100 is not required, and productivity of the power conversion device 100 can be improved.

Capacitor element 5 is thermally connected to cooling surface 2b of cooler 2 via heat radiating metal body 4 and heat radiating wall 6a of capacitor case 6. Therefore, the capacitor element 5 can be cooled by the cooler 2 having a simple structure without providing a complicated cooling structure surrounding the capacitor element 5. Since one end of one of the positive-side bus bar 7a and the negative-side bus bar 8a is disposed opposite to the heat radiation wall 6a in the interior of the capacitor case 6, the one of the positive-side bus bar 7a and the negative-side bus bar 8a is efficiently cooled by the cooling surface 2b of the cooler 2. Since the plate-shaped intermediate connection portion 22 of the other of the positive-side bus bar 7a and the negative-side bus bar 8a and the plate-shaped portion 4b of the heat radiating metal body 4 are thermally connected, the other of the positive-side bus bar 7a and the negative-side bus bar 8a is efficiently cooled by the cooling surface 2b of the cooler 2 through the heat radiating metal body 4. Further, the capacitor element 5, the positive-side bus bar 7a, and the negative-side bus bar 8a can be cooled without complicating the refrigerant flow path 2a inside the cooler 2.

Screws, or soldering or the like are used to connect the bus bars extending from the semiconductor module 1 and the bus bars extending from the capacitor module 3. Therefore, a space for connecting the bus bars to each other is required between the semiconductor module 1 and the capacitor module 3. As shown in fig. 1, a connection portion 4a for thermally connecting the cooler 2 and the heat radiating metal body 4 can be arranged by utilizing the space. By disposing the connection portions 4a with this space, the cooling capability of the capacitor element 5 and the like can be enhanced using the heat-radiating metal body 4 without increasing the space occupied by the capacitor module 3 and the semiconductor module 1. Further, since the occupied space including the mounting portion of the capacitor module 3 is not increased, the position where the connecting portion 4a is disposed may be a position almost parallel to the space where the capacitor module fixing portion 14 is disposed. The method of connecting the bus bars provided in the semiconductor module 1 and the capacitor module 3 is not limited to screw fastening or welding.

In the present embodiment, the capacitor module 3 and the semiconductor module 1 are disposed on the same plane, i.e., the cooling surface 2b of the cooler 2, but the arrangement of the capacitor module 3 and the semiconductor module 1 is not limited to the same plane. If the capacitor module 3 and the semiconductor module 1 are connected with low wiring inductance and the assembly of the power conversion device 100 is easy, the capacitor module 3 and the semiconductor module 1 may not be arranged on the same plane. For example, as shown in fig. 4, the cooling surface 2b of the cooler 2 may have a step, and the capacitor module 3 and the semiconductor module 1 may be disposed on the respective surfaces. Even in such a configuration, the capacitor module 3 and the semiconductor module 1 can be connected with low wiring inductance, and the power conversion device 100 can be easily assembled. The capacitor module 3 and the semiconductor module 1 may be configured to sandwich the cooler 2.

In the present embodiment, since the plate-like portion 4b of the heat radiating metal body 4 and the intermediate connecting portion 22 are disposed inside the capacitor case 6, the plate-like portion 4b of the heat radiating metal body 4 and the intermediate connecting portion 22 are thermally connected by the filling resin 9 as an insulating member, but the insulating member is not limited to the filling resin 9. A structure-retaining resin formed of an insulating material may be provided between the plate-shaped portion 4b of the heat-radiating metal body 4 and the intermediate connection portion 22 in place of the filling resin 9, and an insulating paper may be configured to be sandwiched between the plate-shaped portion 4b of the heat-radiating metal body 4 and the intermediate connection portion 22.

As described above, in the power conversion device 100 of embodiment 1, the heat-dissipating metal body 4 is provided, the heat-dissipating metal body 4 has the plate-like portion 4b, the plate-like portion 4b is opposed to and thermally connected to the plate-like intermediate connecting portion 22 between the one end and the other end of the positive-side bus bar 7a via the filling resin 9, and the heat-dissipating metal body 4 is thermally connected to the cooling surface 2b of the cooler 2, so that the cooling performance of the positive-side bus bar 7a as a heat generating member can be improved, and the capacitor element 5 can be protected from a temperature rise. Even if heat is generated at the portion of capacitor element 5 on the side of opposing wall 6b remote from cooling surface 2b of cooler 2, it can be cooled by heat radiating metal member 4. Since the metal heat dissipating body 4 is disposed inside the capacitor case 6, a process of providing the metal heat dissipating body 4 to the power conversion device 100 is not required, and the productivity of the power conversion device 100 can be improved.

Since capacitor element 5 is thermally connected to cooling surface 2b of cooler 2 via heat-dissipating metal body 4 and heat-dissipating wall 6a of capacitor case 6, capacitor element 5 can be protected from temperature increase by cooler 2 having a simple structure without providing a cooler having a complicated cooling structure surrounding capacitor element 5. Further, since the capacitor module 3 and the semiconductor module 1 are close and the capacitor module 3 and the semiconductor module 1 are connected by the bus bar of low wiring inductance, heat generation due to joule heat of the bus bar is suppressed and the capacitor element 5 can be protected from temperature rise.

Embodiment 2.

The power conversion device 100 of embodiment 2 will be explained. Fig. 5 is a cross-sectional view schematically showing the power conversion device 100 according to embodiment 2. Fig. 5 is a main portion sectional view of the power conversion device 100 cut off at a sectional position a-a of fig. 1, and is a diagram with the inside of the cooler 2 omitted. The power conversion device 100 according to embodiment 2 is configured such that the polarity of the bus bar disposed on the heat radiation wall 6a side of the capacitor case 6 is defined.

Inside the semiconductor module 1c surrounded by the protective member 21, the semiconductor element 13 is connected to the conductive member 15 via the joining member 16. The joining member 16 is, for example, solder. The conductive member 15 is, for example, a metal plate having conductivity. The conductive member 15 is thermally connected to the cooling surface 2b of the cooler 2 via an insulating joint member 17. When a plurality of semiconductor elements 13 are provided, an internal bus bar 19 for connecting the semiconductor elements 13 and the conductive member 15 is provided. The external terminal 18 is a terminal for outputting the power converted to the outside.

The polarity of one of the positive-side bus bar 7a and the negative-side bus bar 8a disposed inside the capacitor case 6 on the heat radiation wall 6a side of the capacitor case 6 is the polarity of the one of the positive-side module bus bar 7b and the negative-side module bus bar 8b having a longer wiring length inside the semiconductor module 1. Here, the wiring length of the negative-side module bus bar 8b inside the semiconductor module 1 is longer than that of the positive-side module bus bar 7 b. Therefore, the polarity of the bus bar disposed on the heat radiation wall 6a side of the capacitor case 6 is a negative electrode, and the negative electrode side bus bar 8a is disposed on the heat radiation wall 6a side.

In order to facilitate the arrangement of the semiconductor elements 13 inside the semiconductor module 1, the wiring length inside the semiconductor module 1 in the positive electrode side module bus bar 7b and the negative electrode side module bus bar 8b may be short and long. The bus bars provided inside the semiconductor module 1 are often limited in thickness or width, and cannot easily expand the cross-sectional area. Therefore, the bus bar having a long wiring length is likely to generate heat by joule heat. Particularly when the power conversion device 100 has a high output density, in a bus bar having a long wiring length, a temperature increase due to heat generation becomes significant.

According to this configuration, the negative-side bus bar 8a connected to the negative-side module bus bar 8b having a long wiring length is arranged on the heat radiation wall 6a side. Since the negative-side bus bar 8a is close to the cooling surface 2b of the cooler 2, the cooling performance of both the negative-side module bus bar 8b and the negative-side bus bar 8a, which are heat generating members, is improved, and the capacitor element 5 can be protected from temperature increase. Even in a case where the ability to cool the bus bars in the semiconductor module 1 only by the portion of the cooler 2 in contact with the semiconductor module 1 may be insufficient, the bus bars in the semiconductor module 1 can be efficiently cooled from the capacitor module 3 side.

In the capacitor case 6, the polarity of one of the positive-side bus bar 7a and the negative-side bus bar 8a disposed on the heat radiation wall 6a side of the capacitor case 6 is the polarity of the bus bar that is directly electrically connected to the semiconductor element 13 in the semiconductor module 1, of the positive-side module bus bar 7b and the negative-side module bus bar 8 b. Here, the negative-side module bus bar 8b is directly electrically connected to the semiconductor element 13. Therefore, the polarity of the bus bar disposed on the heat radiation wall 6a side of the capacitor case 6 is a negative electrode, and the negative electrode side bus bar 8a is disposed on the heat radiation wall 6a side.

Inside the semiconductor module 1, either one of the positive-side module bus bar 7b and the negative-side module bus bar 8b is electrically connected directly to the semiconductor element 13. The one bus bar which is directly electrically connected is also directly thermally connected to the semiconductor element 13. Since the semiconductor element 13 is thermally connected to the cooling surface 2b of the cooler 2 via the joining member 16, the conductive member 15, and the insulating joining member 17, the bus bar directly connected to the semiconductor element 13 is less likely to be subjected to the cooling effect of the cooler 2. The bus bar directly connected to the semiconductor element 13 receives heat generated by the semiconductor element 13 and easily transfers the heat to the capacitor module 3.

According to this configuration, the negative-side bus bar 8a connected to the negative-side module bus bar 8b directly connected to the semiconductor element 13 is disposed on the heat radiation wall 6a side. Since the negative-side bus bar 8a is brought close to the cooling surface 2b of the cooler 2, the cooling performance of the negative-side module bus bar 8b and the negative-side bus bar 8a, which are heat generating members, can be improved, and the capacitor element 5 can be protected from temperature increase. Even in a case where the ability to cool the bus bars in the semiconductor module 1 only by the portion of the cooler 2 in contact with the semiconductor module 1 may be insufficient, the bus bars in the semiconductor module 1 can be efficiently cooled from the capacitor module 3 side.

On the other hand, inside the semiconductor module 1, the positive-side module bus bar 7b is connected to the conductive member 15 near the cooler 2. Since the positive-side module bus bar 7b is cooled by the portion of the cooler 2 that is in contact with the semiconductor module 1, the amount of heat received from the semiconductor element 13 is small. However, when the power conversion apparatus 100 has a high output density, the amount of heat generated from the positive-side module bus bar 7b due to joule heat becomes large, and thermal damage may be caused to the capacitor element 5. In the present embodiment, since the heat radiating metal member 4 is also provided as in embodiment 1, the positive-side bus bar 7a connected to the positive-side module bus bar 7b is cooled by the heat radiating metal member 4, and therefore the capacitor element 5 can be protected from a temperature increase.

In the present embodiment, the amount of heat generated by joule heat of the bus bar itself in the negative-side bus bar 8a and the negative-side module bus bar 8b and the amount of heat received from the semiconductor element 13 are larger than the amount of heat generated by joule heat of the bus bar itself in the positive-side bus bar 7a and the positive-side module bus bar 7 b. That is, in the negative electrode-side bus bar 8a and the negative electrode-side module bus bar 8b, the degree of influence of thermal damage to the capacitor element 5 is large. On the other hand, as for the cooling capacity, the cooling capacity by the cooler 2 via the heat radiation wall 6a of the capacitor case 6 is superior to the cooling capacity by the heat radiating metal body 4. Therefore, in the present embodiment, the cooling efficiency is optimized by combining the case where both the degree of influence of the thermal damage and the cooling capacity are large, and the case where both the degree of influence of the thermal damage and the cooling capacity are small.

As described above, in the power conversion device 100 of embodiment 2, since the negative-side bus bar 8a connected to the negative-side module bus bar 8b having a long wiring length is arranged on the heat radiation wall 6a side, the cooling performance of the negative-side module bus bar 8b as a heat generating member can be improved, and the capacitor element 5 can be protected from a temperature increase. Further, since the negative-side bus bar 8a connected to the negative-side module bus bar 8b directly connected to the semiconductor element 13 is disposed on the heat radiation wall 6a side, the cooling performance of the negative-side module bus bar 8b as a heat generating member can be improved, and the capacitor element 5 can be protected from a temperature increase.

Embodiment 3.

The power conversion device 100 according to embodiment 3 will be explained. Fig. 6 is a cross-sectional view schematically showing the power conversion device 100 according to embodiment 3. Fig. 6 is a main portion sectional view of the power conversion device 100 cut off at the same position as the a-a sectional position of fig. 1, and is a view in which the insides of the semiconductor module 1c and the cooler 2 are omitted. In the power conversion device 100 according to embodiment 3, the heat radiating metal body 4 is disposed at a position different from that of embodiment 1.

Plate-shaped portion 4b and intermediate connection portion 22 of heat radiating metal body 4 are disposed outside capacitor case 6. The plate-like portion 4b of the heat radiating metal body 4 and the intermediate connecting portion 22 face each other with the insulating material 12 interposed therebetween. The insulating material 12 is, for example, a structure-retaining resin or an insulating paper, but is not limited thereto. Here, the heat radiating metal member 4 and the capacitor case 6 are provided separately from the capacitor module 3 with a gap therebetween, but may be provided integrally with the capacitor module 3.

As described above, in the power conversion device 100 of embodiment 3, since the plate-like portion 4b of the heat radiating metal body 4 and the intermediate connection portion 22 are disposed outside the capacitor case 6, the intermediate connection portion 22 is cooled outside the capacitor case 6, and therefore the heat received from the semiconductor module 1 and the heat generated from the positive-side bus bar 7a are not transmitted to the capacitor element 5, and the capacitor element 5 can be protected from a temperature increase.

Embodiment 4.

The power conversion device 100 of embodiment 4 will be explained. Fig. 7 is a cross-sectional view schematically showing the power conversion device 100 according to embodiment 4. Fig. 7 is a main portion sectional view of the power conversion apparatus 100 cut at a sectional position a-a of fig. 1, and is a view in which the inside of the semiconductor module 1c is omitted. The power conversion apparatus 100 according to embodiment 4 is configured to define the direction of the refrigerant flowing inside the cooler 2 and the arrangement of the semiconductor module 1 and the capacitor module 3.

The cooler 2 includes a coolant flow path 2a inside thereof, and the coolant flow path 2a causes coolant to flow from the coolant inlet 10 toward the coolant outlet 11 in a direction parallel to the cooling surface 2b outside the cooler 2 in which the capacitor module 3 and the semiconductor module 1 are arranged. The direction of the refrigerant flow is the direction of the arrows shown in fig. 7. The space inside the cooler 2 is defined as the refrigerant flow path 2a, but may have another shape of the refrigerant flow path 2 a. For example, a tubular flow path formed by a pipe may be used, and a fin may be provided inside or outside the refrigerant flow path 2 a.

The capacitor module 3 is disposed on the cooling surface 2b of the cooler 2 on the upstream side of the refrigerant flow path 2a, and the semiconductor module 1 is disposed on the cooling surface 2b of the cooler 2 on the downstream side of the refrigerant flow path 2 a. Generally, with respect to heat generation in the power conversion apparatus 100, heat generation at the semiconductor module 1 is larger than heat generation at the capacitor module 3. Since the heat exchanging with the refrigerant in the cooler 2 also has the same relationship, the heat at the semiconductor module 1 is large. Therefore, when the capacitor module 3 is disposed at the upstream side portion, the temperature of the refrigerant supplied to the heat radiation wall 6a side of the capacitor case 6 is low, and since the heat generation of the capacitor module 3 is smaller than the heat generation of the semiconductor module 1, the refrigerant having a relatively low temperature can also be supplied to the cooling surface 2b side where the semiconductor module 1 is disposed. When the flow direction of the refrigerant is opposite to that of the present embodiment, the refrigerant having a relatively low temperature is supplied to the side of the cooling surface 2b where the semiconductor module 1 is arranged, but the refrigerant having a relatively high temperature is supplied to the side of the heat radiation wall 6a of the capacitor case 6, so that the cooling efficiency is deteriorated. In the present embodiment, since the direction of the refrigerant is appropriately set, the cooling efficiency of the power conversion apparatus 100 is improved, and the capacitor element 5 can be protected from a temperature increase.

As described above, in the power conversion device 100 according to embodiment 4, since the capacitor module 3 is disposed on the cooling surface 2b of the cooler 2 on the upstream side of the refrigerant flow path 2a and the semiconductor module 1 is disposed on the cooling surface 2b of the cooler 2 on the downstream side of the refrigerant flow path 2a, the semiconductor module 1 generating a large amount of heat is disposed on the downstream side, whereby the cooling efficiency of the power conversion device 100 can be improved and the capacitor element 5 can be protected from a temperature increase.

In the above, the power conversion apparatus 100 is described as an example of a power conversion apparatus that outputs three-phase alternating current. However, the power conversion apparatus 100 may be various power conversion apparatuses such as a DC-DC converter, and the capacitor module 3 may be provided in each portion requiring smoothing such as an output side connected to a load. The capacitor module 3 is not limited to the semiconductor module 1, and may be a substrate provided with a semiconductor switching element, for example.

Although various exemplary embodiments and examples have been described in the present application, the various features, modes, and functions described in 1 or more embodiments are not limited to the application to specific embodiments, and may be applied to the embodiments alone or in various combinations.

Therefore, it is considered that innumerable modifications that are not illustrated are also included in the technical scope disclosed in the present specification. For example, it is assumed that the case where at least one component is modified, added, or omitted, and the case where at least one component is extracted and combined with the components of other embodiments are included.

Description of the reference symbols

1a semiconductor module, 2a cooler, 2a refrigerant flow path, 2b cooling surface, 3 a capacitor module, 4 heat-radiating metal body, 4a connection portion, 4b plate-like portion, 5 capacitor element, 5a first terminal, 5b second terminal, 6 capacitor case, 6a heat-radiating wall, 6b opposing wall, 7a positive-side bus bar, 7b positive-side module bus bar, 8a negative-side bus bar, 8b negative-side module bus bar, 9 filling resin, 10 refrigerant inlet, 11 refrigerant outlet, 12 insulating material, 13 semiconductor element, 14 capacitor module fixing portion, 15 conductive member, 16 bonding member, 17 insulating bonding member, 18 external terminal, 19 internal bus bar, 20 heat-radiating grease, 21 protection member, 22 intermediate connection portion, 100 power conversion device.