CN112636607A - Power conversion device - Google Patents

Abstract

The present invention provides a power conversion device, comprising: the power module case includes, as the bus bar, a first bus bar and a second bus bar which are disposed in parallel and face each other, and the power module case has a bus bar exposure opening which exposes a surface of the first bus bar opposite to the second bus bar.

Description

Power conversion device

Technical Field

The present invention relates to a power conversion device.

The present application is based on the priority claim of Japanese patent application No. 2019-172853, filed in Japan 24.9.2019, the contents of which are incorporated herein by reference.

Background

In a vehicle such as an electric vehicle, a Power conversion device (PCU) is provided between a battery and a motor. Such a power conversion device includes a plurality of power devices (power semiconductor chips) and a power module case that houses the power devices. For example, as disclosed in japanese patent application laid-open No. 2014-187818, a bus bar serving as a current-carrying path is housed in the power module case. The bus bar and the power device are connected by solder.

Problems to be solved by the invention

However, when soldering such a bus bar and a power device, it is common to melt solder in a reflow furnace and connect the bus bar and a terminal of the power device. However, in the reflow step, the entire power module case including the bus bar is heated in a reflow furnace. In the reflow step, the bus bar needs to be heated to a target temperature. Therefore, the power module is maintained in a high temperature state in the reflow oven until the bus bar reaches the target temperature. In order to reduce the load on the power module case in the reflow step, it is desirable to shorten the time for raising the temperature of the bus bar.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object of the present invention is to shorten a temperature increase time of a bus bar in a reflow soldering process in a power converter.

Means for solving the problems

The present invention adopts the following means as means for solving the above problems.

The first scheme adopts the following structure: a power conversion device is provided with: a bus bar; a power module housing holding the bus bar; and a power device connected to the bus bar by solder, the power device including, as the bus bar, a first bus bar and a second bus bar arranged in parallel and facing each other, wherein the power module case has a bus bar exposing opening that exposes a surface of the first bus bar opposite to a facing surface of the second bus bar.

Second aspect in the first aspect described above, the following structure is employed: the plurality of bus bar exposure openings are provided in a dispersed manner along the extending direction of the first bus bar.

Third aspect in the second aspect described above, the following structure is adopted: the power module case has a bridge portion that is disposed between the bus bar exposure openings and that includes a bridge conduction path that spans the first bus bar.

The fourth aspect employs the following configuration in any one of the first to third aspects: the bus bar has: a base portion formed in an elongated plate shape, and a connection portion protruding from a side edge portion of the base portion and connected to the power device with solder, the power module case being molded without exposing the side edge portion of the base portion.

A fifth aspect is any of the first to fourth aspects, wherein the structure is as follows: the plurality of power devices are arranged with the first bus bar interposed therebetween in a direction orthogonal to an extending direction of the first bus bar when viewed from an arrangement direction of the first bus bar and the second bus bar.

Effects of the invention

According to the above aspects of the present invention, the first bus bar and the second bus bar are arranged in parallel to face each other, and a part of a surface of the first bus bar opposite to a facing surface of the second bus bar is exposed through the bus bar exposure opening provided in the power module case. Therefore, in the reflow step, in the region exposed through the bus bar exposure opening, the heat in the reflow furnace reaches the first bus bar without being blocked by the power module. As a result, the temperature of the first bus bar can be raised in a short time. The first bus bar and the second bus bar are disposed to face each other. Therefore, the temperature of the second bus bar can be increased in a short time via the first bus bar. Therefore, according to the aspects of the present invention, the temperature increase time of the bus bar in the reflow step can be shortened in the power converter.

Drawings

Fig. 1 is an exploded perspective view showing a schematic configuration of a power converter according to an embodiment of the present invention.

Fig. 2 is a schematic plan view of a power module provided in a power conversion device according to an embodiment of the present invention.

Fig. 3 is a schematic plan view of a power module in which a bus bar is indicated by a solid line, the power module being provided in a power conversion device according to an embodiment of the present invention.

Fig. 4A is a sectional view a-a of fig. 2.

Fig. 4B is a sectional view B-B of fig. 2.

Description of the reference numerals

1 power conversion device, 2 smart power module, 3 capacitor, 4 body case, 10 power module, 10a power device, 10a1 terminal, 10b power module case, 10b1 accommodating recess, 10b2 central bus bar holding portion, 10b3 bus bar exposing opening, 10b4 bridge portion, 10b5 connecting terminal, 10c bus bar, 10d water jacket, 10e upper bus bar (first bus bar), 10f lower bus bar (second bus bar), 10g bridge bus bar (bridge conducting path), 10h insulating layer, 10i base, 10j connecting portion, 10k solder, 11 circuit board

Detailed Description

Hereinafter, an embodiment of a power converter according to the present invention will be described with reference to the drawings.

Fig. 1 is an exploded perspective view showing a schematic configuration of a power converter 1 according to the present embodiment. The power converter 1 of the present embodiment is mounted on a vehicle such as an electric vehicle, and is provided between a motor (load) and a battery (not shown). As shown in fig. 1, the power converter 1 of the present embodiment includes a smart power module 2, a capacitor 3, and a main body case 4.

The smart power module 2 includes a power module 10, a circuit board 11, a current sensor, and the like, which are not shown. The power module 10 includes: a plurality of power devices 10a (see fig. 2) having power semiconductor elements (not shown), a power module case 10b holding the power devices 10a, a bus bar 10c (see fig. 2) connected to the power devices 10a, a water jacket 10d for cooling, and the like. The circuit board 11 is stacked on the power module 10, and includes a drive circuit and the like for driving the power device 10 a. The current sensor, not shown, is a sensor for detecting a current flowing through the bus bar 10c, and is held by the power module case 10 b.

The capacitor 3 is connected to the smart power module 2 and is disposed on the opposite side of the circuit board 11 with the power module 10 interposed therebetween. The main body case 4 is a case that houses the smart power module 2 and the capacitor 3, and includes an upper case 4a, a center case 4b, and a lower case 4 c. The upper case 4a, the center case 4b, and the lower case 4c are connected so as to be dividable in the stacking direction of the power module 10 and the circuit board 11. The upper case 4a covers the smart power module 2 from the circuit board 11 side and is fastened to the center case 4 b. The center case 4b contains a reactor therein and covers the periphery of the smart power module 2. The lower case 4c is provided with a connector for connecting the smart power module 2 with the motor, and is fastened to the center case 4 b.

The power conversion device 1 includes a step-up/down circuit and an inverter circuit each including a power device, a capacitor 3, a reactor, and the like. The power conversion device 1 converts electric power supplied from a battery into three-phase alternating current power and supplies the three-phase alternating current power to a motor, or returns regenerative electric power from the motor to the battery.

Fig. 2 is a plan view of the power module 10 provided in the power converter 1 according to the present embodiment. As described above, the power module 10 included in the smart power module 2 includes: a plurality of power devices 10a, a power module case 10b holding the power devices 10a, and a bus bar 10c connected to the power devices 10 a.

The power device 10a is a switching device in the form of a chip including a switching element driven by a drive circuit provided on the circuit board 11, and forms, for example, an arm of an inverter circuit. As shown in fig. 2, a plurality of such power devices 10a are arranged so as to sandwich an upper bus bar 10e (and a lower bus bar 10f) described later in plan view. These power devices 10 are arranged along the extending direction of the upper bus bar 10e in each of a region on one side of the upper bus bar 10e (a region on one side of the upper bus bar 10e in the direction orthogonal to the extending direction of the upper bus bar 10 e) and a region on the other side (a region on the other side of the upper bus bar 10e in the direction orthogonal to the extending direction of the upper bus bar 10 e). In the present embodiment, a total of 14 power devices 10a, 7, are arranged in a region on one side of the upper bus bar 10e and a region on the other side of the upper bus bar 10 e.

The power module case 10b is formed of an insulating resin material, and is formed in a substantially rectangular shape with the direction in which the upper bus bar 10e (and the lower bus bar 10f) extends as the longitudinal direction. The power module case 10b has the same number of receiving recesses 10b1 as the power devices 10a for receiving the power devices 10 a.

The power module case 10b has a central bus bar holding portion 10b2 extending linearly in the longitudinal direction at a substantially central portion in the width direction in plan view. The central bus bar holding portion 10b2 is a portion that encloses the upper bus bar 10e and the lower bus bar 10 f. The power module case 10b of the present embodiment has a plurality of bus bar exposure openings 10b3 formed with respect to the central bus bar holding portion 10b 2.

These bus bar exposure openings 10b3 are openings that expose a part of the surface of the upper bus bar 10 e. Such bus bar exposure openings 10b3 are aligned along the direction in which the upper bus bar 10e extends (extending direction). That is, in the present embodiment, the power module case 10b is provided with a plurality of bus bar exposure openings 10b3 distributed along the extending direction of the upper bus bar 10 e.

Bridge portions 10b4 are provided between the bus bar exposing openings 10b 3. That is, a plurality of bridges 10b4 are provided, and the bridges 10b4 are aligned along the upper bus bar 10e similarly to the bus bar exposure openings 10b 3. A bridge bus bar 10g (bridge conduction path extending across the upper bus bar 10 e) described later is contained in the bridge portions 10b 4. In this way, in the present embodiment, the power module case 10b includes the bridge portions 10b4, and the bridge portions 10b4 are disposed between the bus bar exposure openings 10b3 and enclose the bridge bus bar 10g that spans the upper bus bar 10 e.

A plurality of connection terminals 10b5 for electrical connection to the capacitor 3, a motor connector, and the like are provided on the side surface of the power module case 10 b. Several of these connection terminals 10b5 are connected to, for example, a bridge busbar 10 g. The power module case 10b is provided with a plurality of terminals for electrically connecting the power device 10a and the circuit board 11.

The bus bar 10c is a current path for passing current between a battery, not shown, and a motor, not shown, and is formed of copper, for example. In the present embodiment, the power module 10 includes an upper bus bar 10e (first bus bar), a lower bus bar 10f (second bus bar), and a bridge bus bar 10g as the bus bar 10 c.

Fig. 3 is a schematic plan view of the power module 10 in which the bus bar 10c is indicated by a solid line. In addition, fig. 4A is a sectional view a-a of fig. 2, and fig. 4B is a sectional view B-B of fig. 2. For example, as shown in fig. 4A and 4B, the upper bus bar 10e and the lower bus bar 10f are arranged in parallel so as to face each other. The upper bus bar 10e is disposed above the lower bus bar 10f, and the lower bus bar 10f is disposed below the upper bus bar 10 e. The upper bus bar 10e and the lower bus bar 10f extend substantially linearly along the longitudinal direction of the power device 10a in a plan view (as viewed from the arrangement direction of the upper bus bar 10e and the lower bus bar 10 f). These upper bus bar 10e and lower bus bar 10f are connected to a battery (voltage boosting circuit), a capacitor 3, and the like, not shown, via a connection terminal 10b5 provided in the power module case 10 b.

An insulating layer 10h is provided between the upper bus bar 10e and the lower bus bar 10 f. The insulating layer 10h may be formed of, for example, a resin, may be formed of a part of the power module case 10b, or may be a member separate from the power module case 10 b.

As shown in fig. 4A, each of the upper bus bar 10e and the lower bus bar 10f includes: a base portion 10i formed in an elongated plate shape, and a connecting portion 10j protruding upward from a side edge portion of the base portion 10 i. The connection portion 10j is a portion connected to the terminal 10a1 of the power device 10a via solder 10 k. The connection portions 10j are provided discretely in the extending direction of the upper bus bar 10e and the lower bus bar 10f in accordance with the arrangement position of the terminals 10a1 of the power device 10 a.

In the present embodiment, of the front and back surfaces of the base portion 10i formed in a plate shape of the upper bus bar 10e, the surface opposite to the surface facing the lower bus bar 10f is exposed through the bus bar exposure opening 10b 3. On the other hand, the side edge of the base 10i formed in a plate shape is covered with the power module case 10b except for the region where the connection portion 10j is provided. That is, the side edge portion of the base portion 10i is molded without being exposed by the power module case 10 b.

The bridge bus bar 10g is, for example, a bus bar 10c that connects the power device 10a disposed in one region of the upper bus bar 10e in plan view and the power device 10a disposed in the other region of the upper bus bar 10e in plan view. The bridge bus bar 10g is a bus bar 10c to which the power device 10a, the capacitor 3, a connector of the motor, and the like are connected. As shown in fig. 4B, the bridge busbar 10g is provided so as to straddle the upper busbar 10e and the lower busbar 10f, and is enclosed in a state covered from above by the bridge portion 10B4 of the power module case 10B.

When manufacturing the power converter 1 of the present embodiment as described above, the bus bar 10c is joined to the power device 10a with the solder 10k in the reflow step when assembling the power module 10. Specifically, first, the power module case 10b enclosing the bus bar 10c is formed with the connection portion 10j exposed, and the power device 10a is disposed in the accommodation recess 10b1 of the power module case 10 b. Thereafter, solder is placed in contact with the connection portion 10j and the terminal 10a1 of the power device 10a, and the power module case 10b and the power device 10a are placed in a reflow furnace and heated, whereby the bus bar 10c is joined to the power device 10a with the solder 10 k.

As described above, the power conversion device 1 of the present embodiment includes: the bus bar 10c, the power module case 10b holding the bus bar 10c, and the power device 10a connected to the bus bar 10c by solder. Further, in the power converter 1 of the present embodiment, the upper bus bar 10e and the lower bus bar 10f arranged in parallel in opposition to each other are provided as the bus bar 10c, and the power module case 10b has the bus bar exposure opening 10b3 that exposes the surface of the upper bus bar 10e opposite to the opposing surface opposing the lower bus bar 10 f.

According to the power converter 1 of the present embodiment, the upper bus bar 10e is disposed in parallel with the lower bus bar 10f so as to face each other, and a part of the surface of the upper bus bar 10e opposite to the facing surface of the lower bus bar 10f is exposed through the bus bar exposure opening 10b3 provided in the power module case 10 b. Therefore, in the reflow step, in the region exposed through the bus bar exposure opening 10b3, the heat in the reflow furnace reaches the upper bus bar 10e without being blocked by the power module case 10 b. As a result, the temperature of the upper bus bar 10e can be raised in a short time. Further, since the upper bus bar 10e and the lower bus bar 10f are disposed to face each other, the temperature of the lower bus bar 10f can be increased in a short time through the upper bus bar 10 e. Therefore, according to the power converter 1 of the present embodiment, the temperature increase time of the bus bar 10c in the reflow step can be shortened.

In the power converter 1 of the present embodiment, a plurality of bus bar exposure openings 10b3 are provided in a distributed manner along the extending direction of the upper bus bar 10 e. According to the power converter 1 of the present embodiment, the surface of the upper bus bar 10e is exposed at a plurality of locations in the extending direction of the upper bus bar 10e, as compared with the case where the bus bar exposure opening 10b3 is partially provided. Therefore, the temperature of the upper bus bar 10e can be uniformly increased in the extending direction. The temperature of the lower bus bar 10f can be uniformly increased in the extending direction.

In the power conversion device 1 of the present embodiment, the power module case 10b has the bridge 10b4, and the bridge 10b4 is disposed between the bus bar exposing openings 10b3 and encloses the bridge bus bar 10g that spans the upper bus bar 10 e. According to the power conversion device 1 of the present embodiment, the bridge portions 10b4 that enclose the bridge bus bar 10g are disposed between the bus bar exposure openings 10b 3. Therefore, the strength of the power module case 10b can be improved.

In the power conversion device 1 of the present embodiment, the upper bus bar 10e and the lower bus bar 10f include: a base 10i formed in an elongated plate shape, and a connecting portion 10j protruding from a side edge portion of the base 10i and connected to the power device 10a with solder, the power module case 10b is molded without exposing the side edge portion of the base 10 i. According to the power conversion device 1 of the present embodiment, at least the base portions 10i of the upper bus bar 10e and the lower bus bar 10f are molded in the power module case 10 b. Therefore, the upper bus bar 10e and the lower bus bar 10f can be reliably held by the power module case 10b, and insulation of the power module 10 can be ensured.

In the power converter 1 of the present embodiment, the plurality of power devices 10a are arranged across the upper bus bar 10e from a direction orthogonal to the extending direction of the upper bus bar 10e, as viewed from the arrangement direction of the upper bus bar 10e and the lower bus bar 10f (the normal direction of the exposed region of the upper bus bar 10 e). According to the power conversion apparatus 1 of the present embodiment, the plurality of power devices 10a can be arranged close to the upper bus bar 10e (and the lower bus bar 10f) whose temperature rises in a short time, and the plurality of power devices 10a can be joined to the upper bus bar 10e (and the lower bus bar 10f) in a short time.

While preferred embodiments of the present invention have been described above with reference to the drawings, it is to be understood that the present invention is not limited to the above embodiments. The shapes, combinations, and the like of the respective components shown in the above embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the scope of the present invention.

For example, in the above-described embodiment, a configuration in which a plurality of bus bar exposing openings 10b3 are provided is described. However, the present invention is not limited thereto. For example, a structure having a single bus bar exposing opening 10b3 may be employed.

In the above embodiment, the bridge portion 10b4 is configured to enclose the bridge bus bar 10 g. However, the present invention is not limited thereto. For example, the bridge portion 10b4 may not include the bridge bus bar 10 g.

Industrial applicability

According to the present invention, in the power converter, the temperature rise time of the bus bar in the reflow step can be shortened.

Claims (8)

1. A power conversion device is characterized by comprising:

a bus bar;

a power module housing holding the bus bar; and

a power device connected to the bus bar with solder,

the bus bar includes a first bus bar and a second bus bar disposed in parallel and facing each other,

the power module case has a bus bar exposure opening that exposes a surface of the first bus bar that is opposite to an opposing surface of the first bus bar that opposes the second bus bar.

2. The power conversion apparatus according to claim 1,

the plurality of bus bar exposure openings are provided in a dispersed manner along the extending direction of the first bus bar.

3. The power conversion apparatus according to claim 2,

the power module case has a bridge portion that is disposed between the bus bar exposure openings and that includes a bridge conduction path that spans the first bus bar.

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

the bus bar has: a base portion formed in an elongated plate shape, and a connection portion protruding from a side edge portion of the base portion and connected to the power device with solder,

the power module case is molded without exposing the side edge portion of the base portion.

5. The power conversion apparatus according to claim 1,

the plurality of power devices are arranged with the first bus bar interposed therebetween in a direction orthogonal to an extending direction of the first bus bar when viewed from an arrangement direction of the first bus bar and the second bus bar.

6. The power conversion apparatus according to claim 2,

the plurality of power devices are arranged with the first bus bar interposed therebetween in a direction orthogonal to an extending direction of the first bus bar when viewed from an arrangement direction of the first bus bar and the second bus bar.

7. The power conversion apparatus according to claim 3,

the plurality of power devices are arranged with the first bus bar interposed therebetween in a direction orthogonal to an extending direction of the first bus bar when viewed from an arrangement direction of the first bus bar and the second bus bar.

8. The power conversion apparatus according to claim 4,

the plurality of power devices are arranged with the first bus bar interposed therebetween in a direction orthogonal to an extending direction of the first bus bar when viewed from an arrangement direction of the first bus bar and the second bus bar.

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