Power conversion device

Abstract

The present invention relates to a power conversion device. The power conversion device includes: a bus bar through which current flows, a current sensor having a magnetic core surrounding the bus bar, and a power module case having a receiving recess for receiving the magnetic core, and the power conversion device includes an embedded fixture that embeds a part of the receiving recess and fixes the magnetic core to the power module case in a state where a part of the magnetic core is exposed.

Description

Technical Field

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

[0002] This application claims priority based on Japanese Patent Application No. 2019-135860 filed in Japan on July 24, 2019, the contents of which are cited herein. Background Art

[0003] In vehicles such as electric vehicles, a power conversion device (PCU: Power Control Unit) is provided between the battery and the motor. Such a power conversion device includes a plurality of semiconductor power chips and a power module housing for housing these power chips. The power module housing includes a bus bar that serves as a power path. Japanese Patent Publication No. 2017-184384 discloses a power conversion device having a current sensor for detecting the current flowing in such a bus bar.

[0004] Problems to be solved by the invention

[0005] However, the current sensor as described above has a magnetic core. For example, as shown in Japanese Patent Gazette No. 2017-184384, the entire magnetic core is molded by a sealing material. However, when the entire magnetic core is molded in this way, stress caused by thermal expansion and contraction during the reflow process when manufacturing the power module, operation in a high-temperature environment, etc., acts strongly on the magnetic core. The magnetic core is formed into a C-shape in which one end and the other end are arranged facing each other with a gap therebetween. In the magnetic core, it is important to keep the distance between one end and the other end constant in maintaining the detection characteristics. As described above, if the stress caused by the thermal expansion and contraction of the power module housing acts strongly on the magnetic core, the distance between one end and the other end of the magnetic core may change. Therefore, the detection characteristics of the current sensor may change unexpectedly. Summary of the invention

[0006] The present invention has been made in view of the above-mentioned problems, and its object is to prevent the detection characteristics of the current sensor from being unexpectedly changed due to thermal expansion and contraction of the power module case during a reflow soldering process, operation in a high-temperature environment, etc. in an electric power conversion device in which the magnetic core of the current sensor is fixed to the power module case.

[0007] Means for solving problems

[0008] The present invention adopts the following means as means for solving the above-mentioned problems.

[0009] The first scheme adopts the following structure: an electric power conversion device, comprising: a bus bar, the bus bar for current to flow; a current sensor, the current sensor having a magnetic core surrounding the bus bar; and a power module case, the power module case having a receiving recess for receiving the magnetic core, the electric power conversion device having an embedded fixture, the embedded fixture embeds a part of the receiving recess and fixes the magnetic core to the power module case in a state where a part of the magnetic core is exposed.

[0010] Second Means In the first means, the magnetic core is formed into a ring shape with one end and the other end disposed opposite to each other with a gap therebetween, and the embedded fixture includes the one end and the other end of the magnetic core.

[0011] The third scheme adopts the following structure in the above-mentioned second scheme: the power module housing has a bus bar holding portion, the bus bar holding portion is uprightly arranged from the bottom surface of the accommodating recess toward the entrance opening of the accommodating recess and encloses the bus bar, and the magnetic core is fixed in a state where the bus bar holding portion is inserted into the gap between the one end and the other end.

[0012] A fourth aspect adopts a configuration in the third aspect described above in which the magnetic core is in contact with a front end surface of the bus bar holding portion.

[0013] A fifth aspect of the present invention is characterized in that in the fourth aspect, a configuration is adopted in which a front end surface of the bus bar holding portion is fixed to the magnetic core by an adhesive.

[0014] The sixth scheme adopts the following structure in any one of the above-mentioned third to fifth schemes: the embedded fixing part exposes at least a part of the area of ​​the bus bar retaining part that contains the bus bar in the direction from the bottom surface of the receiving recess toward the entrance opening of the receiving recess and buries a part of the receiving recess.

[0015] Effects of the Invention

[0016] In the above-mentioned schemes of the present invention, a magnetic core is accommodated in a receiving recess of a power module housing. In addition, the magnetic core is fixed to the power module housing by an embedded fixing member that buries a portion of the receiving recess. Here, in the above-mentioned schemes, the embedded fixing member only buries a portion of the receiving recess, and a portion of the magnetic core is exposed. That is, in the above-mentioned schemes, a gap is provided inside the receiving recess to expose the magnetic core. By providing such a gap, it is possible to suppress the stress caused by thermal expansion and contraction of the power module housing from being transmitted to the magnetic core, and to prevent the shape of the magnetic core from being deformed. Therefore, according to the above-mentioned schemes, in an electric power conversion device in which the magnetic core of the current sensor is fixed to the power module housing, it is possible to prevent the detection characteristics of the current sensor from changing unexpectedly due to thermal expansion and contraction of the power module housing during the reflow soldering process or during operation in a high-temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an exploded perspective view showing a schematic structure of a power conversion device in one embodiment of the present invention.

[0018] Figure 2 It is a schematic partial cross-sectional view including a current sensor of a power conversion device according to an embodiment of the present invention.

[0019] Figure 3A This is a schematic diagram showing a process of mounting the magnetic core on the power module case.

[0020] Figure 3B This is a schematic diagram showing a process of mounting the magnetic core on the power module case.

[0021] Figure 3C This is a schematic diagram showing a process of mounting the magnetic core on the power module case.

[0022] Description of Reference Numerals

[0023] 1 power conversion device, 2 intelligent power module, 3 capacitor, 4 main body housing, 10 power module, 10a power module housing, 10b bus bar, 10c water jacket, 11 circuit board, 13 current sensor, 13a magnetic core, 13a1 one end, 13a2 other end, 13b Hall sensor, 20 receiving recess, 21 bottom surface, 22 inlet opening, 23 bus bar holding portion, 24 first side surface, 25 second side surface, 26 front end surface, 27 Hall sensor insertion hole, 30 adhesive, 40 embedded fixing member, K gap, S gap DETAILED DESCRIPTION

[0024] Hereinafter, one embodiment of the power conversion device of the present invention will be described with reference to the drawings.

[0025] Figure 11 is an exploded perspective view showing a schematic structure of a power conversion device 1 according to the present embodiment. The power conversion device 1 according to the present embodiment is mounted on a vehicle such as an electric car and is provided between a motor (load) not shown and a battery. Figure 1 As shown, the power conversion device 1 of the present embodiment includes an intelligent power module 2 , a capacitor 3 , and a main body case 4 .

[0026] The intelligent power module 2 includes a power module 10, a circuit board 11, and a current sensor 13 (see Figure 2 ) etc. The power module 10 includes: a plurality of power chips (not shown) having power semiconductor elements, a power module case 10a for holding these power chips, and a bus bar 10b (see Figure 3A , Figure 3B as well as Figure 3C ) and a water jacket 10c for cooling. The circuit substrate 11 is stacked on the power module 10 and has a drive circuit for driving the power chip. The current sensor 13 is a sensor for detecting the current flowing in the bus bar 10b. The detailed structure of the parts including the current sensor 13 will be described later.

[0027] The capacitor 3 is connected to the intelligent power module 2. The capacitor 3 is arranged on the side opposite to the side where the circuit substrate 11 is arranged with respect to the power module 10. The main body housing 4 is a housing for accommodating the intelligent power module 2 and the capacitor 3, and includes an upper housing 4a, a central housing 4b, and a lower housing 4c. These upper housing 4a, central housing 4b, and lower housing 4c are connected in a manner that can be divided in the stacking direction of the power module 10 and the circuit substrate 11. The upper housing 4a covers the intelligent power module 2 from the circuit substrate 11 side and is connected to the central housing 4b. The central housing 4b has a built-in reactor and covers the periphery of the intelligent power module 2. The lower housing 4c is provided with a connector for connecting the intelligent power module 2 to the motor, and is fastened to the central housing 4b.

[0028] The power converter 1 includes a step-up / step-down circuit and an inverter circuit composed of a power chip, a capacitor 3 and a reactor, etc. The power converter 1 converts power supplied from a battery into three-phase AC power and supplies it to a motor, or sends regenerative power from the motor back to the battery.

[0029] Figure 2 1 is a schematic cross-sectional view of the power conversion device 1 at a location where the current sensor 13 is provided. The power conversion device 1 includes a plurality of bus bars 10b provided in the power module 10. Therefore, the current sensor 13 is also provided at a plurality of locations. Figure 2 As shown, each current sensor 13 includes a magnetic core 13 a and a Hall sensor 13 b .

[0030] The magnetic core 13a is formed of a magnetic body such as Figure 2 As shown, the magnetic core 13a1 and the other end 13a2 are arranged to face each other with a gap S between them. The magnetic core 13a is arranged to surround the bus bar 10b in a direction perpendicular to the direction of the current bus bar 10b. The Hall sensor 13b is arranged between the one end 13a1 and the other end 13a2 of the magnetic core 13a (i.e., the gap S). The Hall sensor 13b is mounted on the circuit board 11, and converts the magnetic field generated between the one end 13a1 and the other end 13a2 of the magnetic core 13a into an electrical signal and outputs it.

[0031] like Figure 2 As shown, in the power conversion device 1 of the present embodiment, the power module housing 10a has a housing recess 20 for housing the magnetic core 13a. The housing recess 20 is a recess that is recessed from the surface of the power module housing 10a on the side opposite to the circuit substrate 11 toward the circuit substrate 11 side. That is, the housing recess 20 is formed in a shape in which the bottom surface 21 is located on the circuit substrate 11 side and has an inlet opening 22 that opens toward the side opposite to the circuit substrate 11. The depth dimension of the housing recess 20 (the distance dimension from the bottom surface 21 to the inlet opening 22) is greater than the height dimension of the magnetic core 13a. The housing recess 20 has a volume that can house the entire magnetic core 13a.

[0032] In addition, if Figure 2 As shown, in the power conversion device 1 of this embodiment, the power module housing 10a has a bus bar holding portion 23 that is erected from the bottom surface 21 of the receiving recess 20 toward the inlet opening 22. The front and back surfaces of the bus bar 10b face in the direction along the surface of the circuit substrate 11. The bus bar holding portion 23 contains the bus bar 10b. In addition, the bus bar holding portion 23 has a plate-like shape. In the cross section ( Figure 2 In the cross section shown in FIG. 1 , the width dimension of the bus bar holding portion 23 in the direction along the surface of the circuit substrate 11 is smaller than the height dimension of the bus bar holding portion 23 (the dimension in the direction from the bottom surface 21 toward the inlet opening 22).

[0033] The bus bar holding portion 23 is inserted into the gap S of the magnetic core 13a. The front end of the bus bar holding portion 23 is arranged in the area surrounded by the magnetic core 13a. In addition, the bus bar holding portion 23 includes the bus bar 10b at the portion arranged in the area surrounded by the magnetic core 13a. Therefore, Figure 2 As shown, the bus bar 10b is arranged in a region surrounded by the magnetic core 13a.

[0034] Such a bus bar holding portion 23 has a first side surface 24 parallel to one surface of the bus bar 10b contained therein, a second side surface 25 parallel to the other surface of the bus bar 10b, and a front end surface 26 facing the inlet opening 22 side. Figure 2 As shown, the power conversion device 1 of this embodiment includes an adhesive 30 for fixing the magnetic core 13a to the bus bar holding portion 23. One end 13a1 of the magnetic core 13a is arranged opposite to each other on the first side surface 24. In addition, the other end 13a2 of the magnetic core 13a is arranged opposite to each other on the second side surface 25. In addition, the middle part of the magnetic core 13a is joined to the front end surface 26 via the adhesive 30.

[0035] In the power converter 1 of this embodiment, the magnetic core 13a is positioned in the housing recess 20 by abutting the front end surface 26 at the midpoint between the one end 13a1 and the other end 13a2 of the magnetic core 13a.

[0036] In addition, if Figure 2 As shown, the bus bar holding portion 23 is provided with a Hall sensor insertion hole 27 that opens toward the circuit board 11. The Hall sensor insertion hole 27 is set to have a depth dimension that passes through the gap S between the one end 13a1 and the other end 13a2 of the magnetic core 13a. The Hall sensor 13b is inserted into the Hall sensor insertion hole 27.

[0037] In addition, if Figure 2 As shown, the power conversion device 1 of this embodiment includes an embedded fixture 40 that embeds a part of the housing recess 20 and fixes the magnetic core 13a to the power module case 10a. Figure 2 As shown, the embedded fixture 40 is arranged at the bottom of the receiving recess 20 in a state of contacting the bottom surface 21 of the receiving recess 20. In the present embodiment, the height dimension of the embedded fixture 40 from the bottom surface 21 of the receiving recess 20 (the dimension in the direction from the bottom surface 21 toward the inlet opening 22) is about one third of the depth dimension of the receiving recess 20. In this way, since the embedded fixture 40 is embedded in only a part of the receiving recess 20, in the power conversion device 1 of the present embodiment, a gap K is provided in a part of the interior of the receiving recess 20. A part of the magnetic core 13a is exposed in the gap K.

[0038] like Figure 2As shown, such an embedded fixture 40 contains one end 13a1 and the other end 13a2 of the magnetic core 13a. On the other hand, the embedded fixture 40 exposes at least a portion of the region of the bus bar holding portion 23 containing the bus bar 10b in the direction from the bottom surface 21 of the receiving recess 20 toward the inlet opening 22 of the receiving recess 20. The embedded fixture 40 embeds a portion of the receiving recess 20. In the present embodiment, the bus bar 10b is arranged at a position closer to the front end side than the center in the height direction of the bus bar holding portion 23. In the height direction, a portion of the bus bar holding portion 23 containing the bus bar 10b is exposed in the gap K in the receiving recess 20. That is, in the present embodiment, the portion of the bus bar holding portion 23 containing the bus bar 10b is not covered by the embedded fixture 40 and is exposed in the gap K. Therefore, the heat of the bus bar 10b can be discharged to the outside more efficiently.

[0039] Such an embedded fixture 40 is formed of an insulating material having a heat-resistant temperature higher than the temperature in the reflow process, and is preferably formed of a material having a Young's modulus lower than that of the material forming the power module case 10a. By making the Young's modulus of the material forming the embedded fixture 40 lower than that of the material forming the power module case 10a, it is possible to reduce the stress acting on the magnetic core 13a when the power module case 10a is thermally deformed.

[0040] Figure 3A , Figure 3B as well as Figure 3C 1 is a schematic diagram showing the process of mounting the magnetic core 13a on the power module case 10a. Figure 3A As shown in FIG. 1 , when the magnetic core 13a is mounted on the power module case 10a, the power module case 10a is arranged so that the inlet opening 22 of the receiving recess 20 faces upward. Figure 3B As shown in FIG. 1 , the softened adhesive 30 is supplied to the front end surface 26 of the bus bar holding portion 23, and the softened embedding fixture 40 is supplied to the receiving recess 20. Figure 3C As shown, the magnetic core 13a is inserted into the housing recess 20 with the gap S facing downward. At this time, the middle portion of the magnetic core 13a is brought into contact with the front end surface 26 of the bus bar holding portion 23 via the adhesive 30. Next, the adhesive 30 and the embedded fixture 40 are cured, thereby joining the magnetic core 13a to the power module case 10a.

[0041] The power module case 10a in which the magnetic core 13a is arranged in the housing recess 20 in this manner is then subjected to a reflow process for soldering the power chip and the like.

[0042] The power conversion device 1 of the present embodiment as described above includes a bus bar 10b through which current flows, a current sensor 13 having a magnetic core 13a surrounding the bus bar 10b, and a power module case 10a having a housing recess 20 for housing the magnetic core 13a. The power conversion device 1 of the present embodiment also includes an embedded fixture 40 that embeds a portion of the housing recess 20 and fixes the magnetic core 13a to the power module case 10a in a state where a portion of the magnetic core 13a is exposed.

[0043] In the power conversion device 1 of the present embodiment, the embedded fixture 40 is embedded in only a part of the receiving recess 20, and a part of the magnetic core 13a is exposed. That is, in the power conversion device 1 of the present embodiment, a gap K is provided inside the receiving recess 20 to expose the magnetic core 13a. By providing such a gap K, it is possible to suppress the stress caused by the thermal expansion of the power module housing 10a from being transmitted to the magnetic core 13a, and it is possible to prevent the shape of the magnetic core 13a from being deformed. Therefore, according to the power conversion device 1 of the present embodiment, it is possible to prevent the detection characteristics of the current sensor 13 from being accidentally changed due to the thermal expansion of the power module housing 10a during the reflow process, operation in a high temperature environment, etc.

[0044] In the power conversion device 1 of the present embodiment, the magnetic core 13a is formed into a ring shape in which the one end 13a1 and the other end 13a2 are arranged to face each other with a gap S therebetween, and the one end 13a1 and the other end 13a2 of the magnetic core 13a are enclosed in the embedded fixture 40. Therefore, the one end 13a1 and the other end 13a2 are fixed by the embedded fixture 40, and the distance dimension from the one end 13a1 to the other end 13a2 can be more reliably suppressed from changing.

[0045] In the power conversion device 1 of the present embodiment, the power module case 10a includes a bus bar holding portion 23 which is erected from the bottom surface 21 of the receiving recess 20 toward the inlet opening 22 of the receiving recess 20 and contains the bus bar 10b, and the magnetic core 13a is fixed in a state where the bus bar holding portion 23 is inserted into the gap S between the one end 13a1 and the other end 13a2. Therefore, even when a gap K is provided inside the receiving recess 20, the bus bar 10b and the magnetic core 13a can be reliably inserted into the area surrounded by the bus bar 10b and the magnetic core 13a.

[0046] In the power conversion device 1 of the present embodiment, the magnetic core 13a is in contact with the front end surface 26 of the bus bar holding portion 23. Therefore, the magnetic core 13a can be positioned by making the magnetic core 13a in contact with the front end surface 26 of the bus bar holding portion 23. Therefore, according to the power conversion device 1 of the present embodiment, the magnetic core 13a can be easily positioned in the housing recess 20.

[0047] In the power conversion device 1 of this embodiment, the front end surface 26 of the bus bar holding portion 23 is fixed to the magnetic core 13a by the adhesive 30. Therefore, the magnetic core 13a can be prevented from being separated from the bus bar holding portion 23 due to thermal deformation of the power module case 10a, and can be prevented from being accidentally moved.

[0048] In the power conversion device 1 of the present embodiment, the embedded fixture 40 exposes at least a portion of the region of the bus bar holding portion 23 that contains the bus bar 10b in the direction from the bottom surface 21 of the housing recess 20 toward the inlet opening 22 of the housing recess 20, and embeds a portion of the housing recess 20. Therefore, the heat generated by the bus bar 10b can be efficiently discharged to the outside of the power conversion device 1 through the gap K.

[0049] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it is self-evident that the present invention is not limited to the above embodiments. The shapes and combinations of the various structural components shown in the above embodiments are examples, and various changes can be made based on design requirements, etc. within the scope of the main purpose of the present invention.

[0050] For example, in the above embodiment, the front end surface 26 of the bus bar holding portion 23 is bonded to the magnetic core 13a via the adhesive 30. However, the present invention is not limited thereto. A structure in which the front end surface 26 of the bus bar holding portion 23 is in contact with the magnetic core 13a without using the adhesive 30 may also be adopted.

[0051] In the above embodiment, the structure in which the entire one end 13a1 and the entire other end 13a2 of the magnetic core 13a are enclosed in the embedded fixing member 40 is described. However, the present invention is not limited to this. For example, a structure in which only a part of the one end 13a1 and the other end 13a2 of the magnetic core 13a are enclosed in the embedded fixing member 40 may be adopted.

[0052] In the above embodiment, the structure in which only a part of the portion of the bus bar holding portion 23 holding the bus bar 10b is exposed in the gap K is described. However, the present invention is not limited to this, and a structure in which the entire portion of the bus bar holding portion 23 holding the bus bar 10b is exposed in the gap K in the height direction of the bus bar holding portion 23 may be adopted. That is, a structure in which the bus bar 10b and the embedded fixture 40 do not overlap when viewed from a direction orthogonal to the height direction of the bus bar holding portion 23 may be adopted.

[0053] Industrial Applicability

[0054] According to the present invention, in a power conversion device in which a magnetic core of a current sensor is fixed to a power module case, it is possible to prevent the detection characteristics of the current sensor from changing unexpectedly due to thermal expansion and contraction of the power module case during a reflow process or operation in a high temperature environment.

Claims

1. A power conversion device, characterized in that: The power conversion device comprises: A bus bar for current flow; a current sensor having a magnetic core surrounding the bus bar; and a power module housing having a housing recess for housing the magnetic core; The power conversion device includes an embedded fixture that embeds a portion of the housing recess and fixes the magnetic core to the power module case in a state where a portion of the magnetic core is exposed. The magnetic core is formed into a ring shape with one end and the other end arranged facing each other with a gap therebetween. The embedded fixing member contains the one end and the other end of the magnetic core. A gap between the one end and the other end is located inside the receiving recess.

2. The power conversion device according to claim 1, characterized in that: The power module housing has a bus bar holding portion, which is erected from the bottom surface of the receiving recess toward the inlet opening of the receiving recess and contains the bus bar. The magnetic core is fixed in a state where the bus bar holding portion is inserted into a gap between the one end and the other end.

3. The power conversion device according to claim 2, characterized in that: The magnetic core is in contact with a front end surface of the bus bar holding portion.

4. The power conversion device according to claim 3, characterized in that: The front end surface of the bus bar holding portion is fixed to the magnetic core by an adhesive.

5. The power conversion device according to any one of claims 2 to 4, characterized in that: The embedded fixture embeds a portion of the accommodating recess in a direction from the bottom surface of the accommodating recess toward the inlet opening of the accommodating recess so as to expose at least a portion of a region of the bus bar holding portion that includes the bus bar and embed the portion.

6. A power conversion device, characterized in that: The power conversion device comprises: A bus bar for current flow; a current sensor having a magnetic core surrounding the bus bar; and a power module housing having a housing recess for housing the magnetic core; The power conversion device includes an embedded fixture that embeds a portion of the housing recess and fixes the magnetic core to the power module case in a state where a portion of the magnetic core is exposed. The magnetic core is formed into a ring shape with one end and the other end arranged facing each other with a gap therebetween. The embedded fixing member contains the one end and the other end of the magnetic core. The power module housing has a bus bar holding portion, which is erected from the bottom surface of the receiving recess toward the inlet opening of the receiving recess and contains the bus bar. The magnetic core is fixed in a state where the bus bar holding portion is inserted into a gap between the one end and the other end.

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