Power conversion device and method for manufacturing power conversion device

Abstract

This power conversion device is provided with a power module having a switching element for converting direct current to alternating current, and is provided with: a direct current bus bar for supplying the direct current to the switching element; a metal case for accommodating the switching element; and a capacitor that connects the DC bus bar and the housing. The capacitor and the housing are electrically connected by a first connection member that is a conductive adhesive.

Description

Technical Field

[0001] The present invention relates to a power conversion device and a method for manufacturing the power conversion device. Background Art

[0002] In a power conversion device, due to the resonance of the installed Y capacitor, large common mode noise leaks into the battery system. As a result, the problem of not being able to meet EMC regulations (noise standards) arises. As a countermeasure to this problem, for example, the following patent document 1 discloses a semiconductor device having a structure in which an inductor is connected to a water path through a conductive sheet, thereby adjusting the electrostatic capacitance of the insulating layer and the inductance of the inductor to reduce noise. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Publication No. 2015-223010 Summary of the invention Technical problem to be solved by the invention

[0004] In the past, as a countermeasure for the resonance of the Y capacitor, there were the following problems: in order to make it have a larger resistance, for example, it was necessary to change the physical characteristic value to increase the inefficiency of the connection member of the Y capacitor, or even if a countermeasure was adopted to reduce noise by connecting a damping resistor in series, the resistor was mounted using a PCB substrate, which also led to an increase in cost. In addition, even in the absence of a damping resistor, the GND terminal of the Y capacitor is connected to the housing via a welding metal fitting, which may also lead to an increase in the cost of the welding metal fitting and installation.

[0005] An object of the present invention is to provide a power conversion device and a method for manufacturing the power conversion device that achieve both low noise and low cost. Technical means for solving technical problems

[0006] The power conversion device of the present invention is equipped with a power module, which has a switching element that converts direct current into alternating current, and includes: a DC bus bar that supplies the direct current to the switching element; a metal shell that accommodates the switching element; and a capacitor connecting the DC bus bar and the shell, wherein the capacitor and the shell are electrically connected via a first connecting member that is a conductive adhesive. In addition, the power conversion device of the present invention includes: a DC bus bar that provides DC power to a switching element that converts DC power into AC power; a metal shell that accommodates the switching element; and a capacitor that connects the DC bus bar and the shell, and adopts the following manufacturing method: a step portion protruding upward is formed in the shell, the capacitor and the step portion are electrically connected by a first connecting member filled with a thermosetting resin and conductive adhesive in a first adhesive container, the capacitor and the shell are electrically connected by a second connecting member filled in a filling portion formed in the shell at a portion different from the step portion, and the first connecting member and the second connecting member are heated at the same time. Effects of the Invention

[0007] According to the present invention, it is possible to provide a power conversion device and a method for manufacturing the power conversion device that achieve both low noise and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is an explanatory diagram of a power conversion device installed in a vehicle and other drive-related installation components. Figure 2 yes Figure 1 Functional block diagram of a power conversion device. Figure 3 yes Figure 2 A structural diagram of a filter circuit provided in a power conversion device. Figure 4 It is an explanatory diagram of a filter circuit according to one embodiment of the present invention. Figure 5 yes Figure 4 AA section view. Figure 6 It is an explanatory diagram of a resin cover provided in a filter circuit according to one embodiment of the present invention. Figure 7 This is a modified example of the first connecting material container according to one embodiment of the present invention. Figure 8 Yes Figure 7 Diagram applied to filter circuits. Fig. 9 This is the first variant. Fig.10 This is the second variant. Fig.11 This is the third variant. Fig.12 This is the 4th variant. DETAILED DESCRIPTION

[0009] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings. The following description and drawings are examples for illustrating the present invention, and are appropriately omitted and simplified for clarity of the description. The present invention may also be implemented in various other ways. Unless otherwise specified, each structural element may be singular or plural.

[0010] In order to facilitate understanding of the present invention, the positions, sizes, shapes, ranges, etc. of the various structural elements shown in the drawings may not represent actual positions, sizes, shapes, ranges, etc. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0011] (One embodiment of the present invention and overall structure of the device) ( Figure 1 ) The vehicle is equipped with a power conversion device 200 , a battery system 136 , a motor generator MG (Motor Generator) and a transmission TM (Transmission). The power conversion device 200 has a filter circuit 1 , a smoothing capacitor 500 , a power module 150 , a drive circuit 174 and a control circuit unit 172 inside.

[0012] The battery system 136 stores electric energy required for the vehicle to travel, and supplies direct current to the power conversion device 200. The direct current connector 138 is a connector for inputting direct current from the battery system 136 to the power conversion device 200.

[0013] The filter circuit 1 filters noise generated in the power conversion device 200 to prevent the noise from entering the battery system 136 . The smoothing capacitor 500 smoothes the DC power from the battery system 136 , thereby supplying a stable DC power to the inverter circuit unit of the power module 150 .

[0014] The inverter circuit unit of the power module 150 has a switching element that converts direct current into alternating current. The control circuit unit 172 receives a command from a higher-level control device (not shown) via the control connector 430, and sends a drive signal to the drive circuit 174 on the drive substrate. The drive circuit 174 drives the power module 150 by the signal from the control circuit unit 172 on the control substrate. As a result, the switching element of the inverter circuit unit of the power module 150 is operated, and an alternating current is output to the motor generator MG.

[0015] AC terminal 420 transmits the three-phase AC output from power module 150 to motor generator MG. The power generated by motor generator MG is transmitted to the tires via transmission TM.

[0016] ( Figure 2 ) The current sensor 180 is provided near the AC bus bar 421 to detect the AC current output from the power module 150 to the motor generator MG. The current value detected by the current sensor 180 is input to the control circuit unit 172 for feedback processing. The motor control connector 420a receives a signal from the motor generator MG1 and transmits the signal to the control circuit unit 172 through the motor control wiring 435.

[0017] ( Figure 3 ) The filter circuit 1 includes a Y capacitor 4 connected to a positive bus bar 5a for supplying direct current to a switching element, a Y capacitor 4 connected to a negative bus bar 5b, and a first connection member 7 connecting each Y capacitor 4 to the housing 104. The Y capacitor 4 functions as a noise removal capacitor of the power conversion device 200.

[0018] ( Figure 4 , Figure 5 ) The filter circuit 1 includes a DC bus bar 5 for supplying DC power to a switching element, a metal housing 104 for housing the switching element, and a Y capacitor 4 connecting the DC bus bar 5 and the housing 104. The Y capacitor 4 and the housing 104 are electrically connected via a first connecting member 7 which is a conductive adhesive.

[0019] The Y capacitor 4 has a GND terminal 9 (first terminal) and an HV terminal 6 (second terminal). The HV terminal 6 of one Y capacitor 4 is connected to the positive bus bar 5a of the HV bus bar (DC bus bar), and the HV terminal 6 of the other Y capacitor 4 is connected to the negative bus bar 5b. The GND terminals 9 of the Y capacitors 4 are respectively connected to the first connection members 7. The first connection member 7 is a conductive adhesive and is filled in the first adhesive container 10.

[0020] The shell 104 has a step portion 104a protruding upward. The bottom surface of the first adhesive container 10 is in contact with the step portion 104a. The first adhesive container 10 is non-conductive and has a through hole for the GND terminal 9 of the Y capacitor 4 and the positioning pin 8 of the shell 104 to pass through. The positioning pin 8 is connected to the step portion 104a through the through hole of the first adhesive container 10. As a result, the return current to the shell 104 flows from the GND terminal 9 to the positioning pin 8 inside the first connecting member 7, and the current that spreads from the positioning pin 8 to the entire shell 104 and returns to the noise source (switch source) has a component in the opposite direction. As a result, the magnetic field is offset by each other's currents, and low inductance can be achieved. As a result, low noise can be achieved.

[0021] By filling the first connecting member 7, which is a conductive adhesive, into the first adhesive container 10, the positioning pin 8 and the GND terminal 9 are electrically connected. As a result, the noise of the positive bus bar 5a and the negative bus bar 5b is bypassed to the housing 104, and the noise can be filtered. In addition, as a result, the positioning of the adhesive container 10 in the housing 104 and the connection between the first connecting member 7 and the housing 104 can be taken into account at the same time.

[0022] The housing 104 is also connected to the Y capacitor 4 at a portion other than the step portion 104a, and is connected to the bottom surface ( Figure 5 Thus, the Y capacitor 4 is fixed to the housing 104.

[0023] The first connecting member 7 filled in the first adhesive container 10 is filled in the container 10 and electrically connected between the GND terminal 9 and the housing 104, thereby having a resistance. By adjusting the filling amount of the first connecting member 7, a desired damping resistance value can be obtained without deteriorating noise performance. This is because the first connecting member 7 has a material-specific resistivity as a conductive adhesive, and the resistivity can be used to adjust the desired damping resistance value. In addition, the first connecting member 7 is filled in the container 10, thereby preventing the first connecting member 7 from being attached to an unnecessary part of the housing 104.

[0024] The first connecting member 7 can be formed by mixing two kinds of liquids. That is, after the first adhesive container 10 is positioned in the housing 104, the two kinds of adhesives can be mixed in the container 10 to form the first connecting member 7. Therefore, there is no need to mix the two kinds of first connecting members 7 in advance and then fill them in the container 10, so the overall process freedom is improved and productivity is improved.

[0025] Furthermore, the present invention is a device including: a DC bus bar 5, which is composed of a positive bus bar 5a and a negative bus bar 5b for supplying DC power to a switching element that converts DC power into AC power; a metal case 104 that accommodates the switching element; and a Y capacitor 4 that connects the DC bus bar 5 and the case 104. As a manufacturing process of the present device, the following process is adopted: a step portion 104a protruding upward is formed in the case 104, the Y capacitor 4 and the step portion 104a are electrically connected by a first connecting member 7 filled in a first adhesive container 10, which is a thermosetting resin and conductive adhesive, and the Y capacitor 4 and the case 104 are electrically connected by a second connecting member 7a filled in a filling portion 19 formed in the case 104 at a portion different from the step portion 104a, and the first connecting member 7 and the second connecting member 7a are heated at the same time.

[0026] By adopting such a manufacturing process, the resin curing process based on heating only needs to be performed once, which can prevent the assembly time from being extended. As the second connecting member 7a, for example, FIPG (Formed In Place Gasket) is used. The second connecting member 7a can also use the same conductive adhesive as the first connecting member 7, rather than a different type of adhesive from the first connecting member 7, so that low cost can be achieved.

[0027] According to the structure of the present invention, metal fittings for welding and the like for the GND terminal 9 used in the conventional Y capacitor 4 are not required. In addition, the resonance can be attenuated by mounting the Y capacitor 4 to the housing 104 at low cost. Thus, a power conversion device 200 that achieves both low noise and low cost can be provided.

[0028] ( Figure 6 ) The first adhesive container 10 may have a resin cover 12 on its upper portion as a cover of the container 10 for contamination countermeasures, whereby the first connection member 7 is sealed in the container 10. In addition, thereby, it is possible to prevent the first connection member 7 from leaking or splashing from the container 10. In addition, the vibration resistance of the container 10 is improved, and the adhesion with the GND terminal 9 and the positioning pin 8 is maintained.

[0029] Furthermore, by placing the first adhesive container 10 on the reference line 11 (on the plane) formed by the upper surface of the Y capacitor 4 and the upper surface of the step portion 104a, not only the arrangement of the first adhesive container 10 on the housing 104 can be restricted, but also the first connecting member 7 in the container 10 is filled in a manner accumulated on the plane, so that it does not accumulate in one direction. Thus, the positioning pin 8 and the GND terminal 9 can be bonded to each other at approximately the same height in the container 10 by the first connecting member 7. In addition, the stress of the first connecting member 7 against vibration is also dispersed, and it can be expected that the vibration resistance can be improved.

[0030] ( Figure 7 , Figure 8 ) As shown in the figure, the first adhesive container 10 can be configured to have a plurality of inner walls 10b, and the first connecting member 7 is filled in the first adhesive container 10 in a manner of folding back along the plurality of inner walls 10b. Thus, in order to adjust the damping resistance value according to the filling amount of the first connecting member 7 into the container 10, it is possible to consider both the increase in resistance and the low inductance, and adjust the damping resistance value according to the length of the filling portion in the container 10. In addition, by adopting this structure, in the folded portion of the container 10, the currents flowing through the first connecting member 7 are in opposite directions to each other, so the magnetic flux is offset, which helps to reduce the inductance. That is, not only the resistance value can be adjusted, but also the increase in resistance and the low inductance can be considered.

[0031] The figure shows that the first adhesive container 10 is provided with a through hole 13 for inserting a positioning pin 8 and a through hole 14 for a GND terminal 9, wherein the positioning pin 8 is used to fix to the above-mentioned housing 104. With regard to the through holes 13 and 14, by providing two through holes in the container 10, the first adhesive container 10 can be positioned to the housing 104, and installation can be facilitated. In addition, in order to intentionally allow the first connecting member 7 inside to leak to the lower part of the adhesive container 10 so as to fix the adhesive container 10 to the housing 104 and the Y capacitor 4 with a larger area, the diameter of the through hole 13 can be larger than the diameter of the positioning pin 10 by more than 2 mm. As a result, the vibration resistance of the container 10 is improved.

[0032] (Variant 1) ( Fig. 9 ) In the filter circuit 1, the first terminal 9 of the Y capacitor 4 is inserted into the through hole of the first adhesive container 10, and the second terminal 6 is inserted into the through hole formed in the second adhesive container 10a connected to the DC bus bar 5. At this time, the second terminal 6 and the DC bus bar 5 are electrically connected by the first connecting member 7 filled in the second adhesive container 10a. Thus, by providing the first connecting member 7 and the container 10a in the connection between the HV terminal 6 and the DC bus bars 5a, 5b, welding is not required in the connection between the HV terminal 6 and the DC bus bars 5a, 5b.

[0033] Furthermore, the second adhesive container 10a can be formed as a part of the resin 15 for molding the DC bus bars 5a and 5b, thereby reducing the cost of newly manufacturing the second adhesive container 10a and achieving cost reduction.

[0034] (Variant 2) ( Fig.10 ) The fixing member 17 is disposed between the first adhesive container 10 and the step portion 104a of the housing 104. If the position of the container 10 is determined by something other than the positioning pin 8 of the housing 104, the positioning pin 8 can be replaced with a screw 16 and fixed to the step portion 104a. Thus, the fixation of the first adhesive container 10 to the housing 104 is further improved.

[0035] (Variant 3) ( Fig.11 ) The housing 104 can be configured to have a connection member filling portion 19 filled with the first connection member 7. Since the housing 104 has only a recessed portion in which the conductive first connection member 7 is accumulated (filled), the GND terminal 9 of the Y capacitor 4 is electrically connected to the housing 104 through the first connection member 7 and fixed to the housing 104. In addition, the housing 104 has a micro-concave and convex portion 18. In the case where it is desired to increase or decrease the resistance value of the GND terminal 9 and the housing 104 to adjust the damping resistance value, it can be achieved by increasing or decreasing the micro-concave and convex portion 18 and increasing or decreasing the surface area. Thus, even if there is a structure without the adhesive container 10, the noise from the DC bus bars 5a and 5b can be eliminated.

[0036] (Variant 4) ( Fig.12 ) The GND terminal 9 and the HV terminal 6 of the Y capacitor 4 may be the GND terminal 9a and the HV terminal 6a which are bent into an L-shape (hook shape). Fig.11 When the L-shaped Y capacitor 4 is applied to the structure, the welding area of ​​the positive bus bar 5a and the HV terminal 6 can be increased. In addition, since the GND terminal 9a is closer to the housing 104, the first connecting member 7 can be reduced. In addition, in the housing 104, the Y capacitor 4 is strong against the shaking in the left and right directions in the figure.

[0037] When the L-shaped Y capacitor 4 is applied to Figure 4 , Figure 5 In the case of the structure, the through hole of the adhesive container 10 can be set to a size large enough for the GND terminal 9 to pass through. Since it is not a linear terminal, the stress generated by longitudinal and even lateral vibrations has a structure perpendicular to the vibration direction, so the vibration resistance is improved.

[0038] According to one embodiment of the present invention described above, the following effects are achieved.

[0039] (1) The power conversion device 200 includes a power module 150 having a switching element for converting DC power into AC power, and includes: a DC bus bar 5 for supplying DC power to the switching element; a metal housing 104 for housing the switching element; and a Y capacitor 4 connecting the DC bus bar 5 and the housing 104, wherein the Y capacitor 4 and the housing 104 are electrically connected via a first connecting member 7 which is a conductive adhesive. Thus, a power conversion device 200 that achieves both low noise and low cost can be provided.

[0040] (2) The first connecting member 7 is filled in the non-conductive first adhesive container 10. This allows adjustment to a desired damping resistance value.

[0041] (3) The housing 104 has a stepped portion 104a protruding upward, and the bottom surface of the first adhesive container 10 is disposed on a reference line 11 formed by the upper surface of the Y capacitor 4 and the upper surface of the stepped portion 104a. Thus, the first connecting member 7 can be filled in the container 10 to a flat surface without biasing to one side, and vibration resistance can be improved.

[0042] (4) The bottom surface of the first adhesive container 10 is in contact with the step portion 104a. This can reduce inductance and noise.

[0043] (5) The first adhesive container 10 has the through hole 13 through which the positioning pin 8 for fixing to the housing 104 is inserted. This facilitates mounting.

[0044] (6) The diameter of the through hole 13 is larger than the diameter of the positioning pin 8 by 2 mm or more. This can improve the fixity and vibration resistance.

[0045] (7) The Y capacitor 4 includes a first terminal 9 and a second terminal 6. The first terminal 9 is inserted into the through hole 14 of the first adhesive container 10. The second terminal 6 is inserted into the through hole formed in the second adhesive container 10a connected to the DC bus bar 5. The second terminal 6 and the DC bus bar 5 are electrically connected via the first connecting member 7 filled in the second adhesive container 10a. Thus, welding is not required.

[0046] (8) The second adhesive container 10a is formed as a part of the resin 15 for molding the DC bus bar 5. This can reduce the number of adhesive containers 10 and achieve cost reduction.

[0047] (9) The first adhesive container 10 has the resin cover 12 on its upper portion. This makes it possible to implement a measure against contamination.

[0048] (10) The first adhesive container 10 has the plurality of inner walls 10b, and the first connecting member 7 is filled in the first adhesive container 10 so as to be folded back along the plurality of inner walls 10b. This can reduce the inductance.

[0049] (11) The first adhesive container 10 is fixed to the step portion 104a by the screw 16. This can take measures against vibration.

[0050] (12) The housing 104 includes the connection member filling portion 19 filled with the first connection member 7. This can reduce the size of the container 10 and achieve cost reduction.

[0051] (13) The power conversion device 200 includes a DC bus bar for supplying DC power to a switching element for converting DC power into AC power; a metal housing 104 for housing the switching element; and a Y capacitor 4 connecting the DC bus bar 5 and the housing 104. Then, a step portion 104a protruding upward is formed in the housing 104, and the Y capacitor 4 and the step portion 104a are electrically connected by a first connecting member 7 filled with a thermosetting resin and conductive adhesive in a first adhesive container 10, and the Y capacitor 4 and the housing 104 are electrically connected by a second connecting member 7a filled in a filling portion 19 formed in the housing 104 at a portion different from the step portion 104a, and the first connecting member 7 and the second connecting member 7a are heated at the same time. By adopting such a method for manufacturing the power conversion device 200, the process can be simplified, and both noise reduction and cost reduction can be achieved.

[0052] (14) Two types of liquids are mixed in the first adhesive container 10 to form the first connecting member 7. This allows limiting the type of adhesive for the first connecting member 7, thereby improving the degree of freedom in the assembly process.

[0053] In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications or combinations of other structures are possible without departing from the scope of the present invention. In addition, the present invention is not limited to having all the structures described in the above-mentioned embodiments, and also includes structures obtained by deleting part of the structures. Description of symbols

[0054] 1 Filter circuit 4 Y capacitors 5 HV busbar 5a Positive bus bar 5b Negative bus bar 6HV terminal (2nd terminal) 6a L-shaped HV terminal 71st connecting member 7a Second connecting member 8 Positioning pins 9GND terminal (1st terminal) 9a L-shaped GND terminal 101st adhesive container 10a Second adhesive container 10b Inner wall 11 Baseline 12 Resin cover 13 Hole for positioning pin 14 GND terminal hole 15 Molding resin 16 Screws 17 Fixed components 18 Micro concave and convex parts 19 Connecting component filling part 104 Housing 104a Step portion.

Claims

1. A power conversion device, comprising a power module, the power module having a switching element for converting direct current into alternating current, the power conversion device comprising: supplying the DC power to a DC bus bar of the switching element; A metal housing for housing the switch element; and a capacitor connecting the DC bus bar and the housing, The capacitor and the case are electrically connected via a first connecting member that is a conductive adhesive.

2. The power conversion device according to claim 1, characterized in that: The first connecting member is filled in a non-conductive first adhesive container.

3. The power conversion device according to claim 2, characterized in that: The housing has a stepped portion protruding upward. The bottom surface of the first adhesive container is disposed on a reference line formed by an upper surface of the capacitor and an upper surface of the step portion.

4. The power conversion device according to claim 3, characterized in that: The bottom surface of the first adhesive container is in contact with the step portion.

5. The power conversion device according to claim 2, characterized in that: The first adhesive container has a through hole through which a positioning pin for fixing to the housing is inserted.

6. The power conversion device according to claim 5, characterized in that: The diameter of the through hole is greater than the diameter of the positioning pin by at least 2 mm.

7. The power conversion device according to claim 5, characterized in that: The capacitor has a first terminal and a second terminal, The first terminal is inserted into the through hole of the first adhesive container. The second terminal is inserted into a through hole formed in a second adhesive container connected to the DC bus bar. The second terminal and the DC bus bar are electrically connected via the first connecting member filled in the second adhesive container.

8. The power conversion device according to claim 7, characterized in that: The second adhesive container is formed as a part of a resin used to mold the DC bus bar.

9. The power conversion device according to claim 2, characterized in that: The first adhesive container has a resin cover on its upper portion.

10. The power conversion device according to claim 2, characterized in that: The first adhesive container has a plurality of inner walls. The first connecting member is filled in the first adhesive container so as to be folded back along the plurality of inner walls.

11. The power conversion device according to claim 3, characterized in that: The first adhesive container is fixed to the step portion by a screw.

12. The power conversion device according to claim 1, characterized in that: The housing includes a connection member filling portion filled with the first connection member.

13. A method for manufacturing a power conversion device, the power conversion device comprising: a DC bus bar for supplying the DC power to a switching element for converting the DC power into AC power; A metal housing for housing the switch element; and a capacitor connecting the DC bus bar and the housing, wherein the manufacturing method is characterized in that: A step portion protruding upward is formed on the housing, The capacitor and the step portion are electrically connected by a first connecting member which is a thermosetting resin and a conductive adhesive filled in a first adhesive container. The capacitor and the case are electrically connected by a second connecting member that is filled in a filling portion formed in the case at a portion different from the step portion. The first connecting member and the second connecting member are heated simultaneously.

14. The method for manufacturing a power conversion device according to claim 13, wherein: In the first adhesive container, two types of liquids are mixed to form the first connecting member.

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