Power converter

Abstract

To provide a power conversion device with high vibration resistance. [Solution] The power conversion device comprises a plurality of stacked power cards 5, 6, a dummy card 120, a plurality of heat exchangers 21, and a case 30. The power cards 5, 6 consist of semiconductor elements that convert power through switching operation, sealed in resin. The plurality of heat exchangers 21 are stacked between the plurality of power cards 5, 6 to cool the power cards 5, 6. The case 30 houses the power cards 5, 6, the dummy card 120, and the heat exchangers 21. At least one of the locations between the plurality of heat exchangers 21 is stacked with a dummy card 120 in place of a power card 5, 6, and the dummy card 120 is fixed to the case 30.

Description

Technical Field

[0003]

[0001] The disclosure in this specification relates to a power conversion device.

Background Art

[0002] Patent Document 1 describes a power conversion device in which a laminate composed of a semiconductor module, a reactor, and a cooling pipe is fixed to a case. In Patent Document 1, the reactor incorporated in the laminate is fixed to the case by a fixing member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when both ends of the laminate are supported, the laminate vibrates with both ends as nodes. That is, the laminate vibrates in a state where a predetermined position in the stacking direction becomes an antinode with the maximum amplitude. However, in the fixing method described in Patent Document 1, the fixing location is limited to the reactor portion. Therefore, it is not possible to select and fix a location close to the antinode of the vibration.

[0005] One object to be disclosed is to provide a power conversion device with high vibration resistance.

Means for Solving the Problems

[0006] To achieve the above objective, a power conversion device according to one aspect of the present disclosure comprises a plurality of stacked power cards (5, 6) each having semiconductor elements (5i, 6i, 5d, 6d) that convert power by switching operation sealed in resin, a dummy card (120) that does not contain semiconductor elements, a plurality of heat exchangers (21) stacked between the plurality of power cards to cool the power cards, and a case (30) that houses the power cards, dummy cards and heat exchangers, wherein dummy cards are stacked in place of power cards at at least one location between the plurality of heat exchangers, and the dummy cards are fixed to the case.

[0007] According to the disclosed power converter, the locations for stacking dummy cards can be selected from among multiple heat exchangers. That is, dummy cards can be placed in the areas near the antinodes of vibration in the stacking direction and fixed to the case. In other words, since the areas with large amplitudes can be fixed to the case, a power converter with high vibration resistance can be provided.

[0008] Furthermore, in order to achieve the above objective, a power conversion device according to another aspect of the present disclosure comprises a plurality of stacked power cards (5, 6) each having semiconductor elements (5i, 6i, 5d, 6d) that convert power by switching operation and sealed in resin, a plurality of heat exchangers (21) stacked between the plurality of power cards to cool the power cards, and a case (30) housing the power cards and heat exchangers, wherein at least one of the plurality of power cards is fixed to the case.

[0009] According to the disclosed power converter, the power card to be fixed can be selected from among multiple power cards arranged in a stack. That is, a power card located near the antinode of vibration in the stacking direction can be selected and fixed to the case. In other words, since the area with the largest amplitude can be fixed to the case, a power converter with high vibration resistance can be provided.

[0010] The reference numbers in parentheses above are merely examples of correspondences with specific configurations in the embodiments described later, and do not limit the technical scope in any way. [Brief explanation of the drawing]

[0011] [Figure 1] This diagram shows the circuit configuration of the power conversion device according to the first embodiment. [Figure 2] This is a schematic plan view of a power conversion device according to the first embodiment. [Figure 3] This is a view taken along line III-III in Figure 2. [Figure 4] This is a view along the line IV-IV in Figure 2. [Figure 5] This is a cross-sectional view of the modified power conversion device, with the fixed portion seen from the X direction. [Figure 6] This is a schematic plan view of a power conversion device according to the second embodiment. [Figure 7] This is a view along the line VII-VII in Figure 6. [Figure 8] This is a cross-sectional view of the power conversion device according to the third embodiment, with the fixed portion viewed from the X direction. [Figure 9] This is a cross-sectional view of the power conversion device according to the fourth embodiment, with the fixed portion viewed from the X direction. [Figure 10] This is a cross-sectional view of the power conversion device according to the fifth embodiment, with the fixed portion viewed from the X direction. [Figure 11] This is a schematic plan view of a power conversion device according to the sixth embodiment. [Figure 12] This is a schematic plan view of the power conversion device according to the seventh embodiment. [Figure 13] This is a view taken along the line XIII-XIII in Figure 12. [Modes for carrying out the invention]

[0012] (First Embodiment) First, the circuit configuration of the power converter will be explained based on Figure 1.

[0013] <Circuit Configuration of Power Conversion Device> The power conversion device 1 is mounted on a vehicle such as an electric vehicle or a hybrid vehicle. The power conversion device 1 converts the DC voltage supplied from the DC power supply 2 mounted on the vehicle into three-phase AC and outputs it to a three-phase AC motor 3 (vehicle-mounted motor). The motor 3 functions as a driving source for the vehicle's travel. The power conversion device 1 can also convert the power generated by the motor 3 into DC and charge the DC power supply 2. The power conversion device 1 enables bidirectional power conversion.

[0014] The power conversion device 1 includes a control board 4, power cards 5, 6, a filter capacitor 7a, a smoothing capacitor 7b, and a reactor 8. The power cards 5, 6 may be referred to as semiconductor modules, power modules, etc.

[0015] The power card 5 is a DC-DC conversion unit and functions as a converter circuit that converts a DC voltage into a DC voltage of a different value. The power card 5 has an upper arm 5U and a lower arm 5L connected in series with each other. The upper arm 5U and the lower arm 5L are composed of a switching element 5i and a diode 5d, which are semiconductor elements. The upper arm 5U and the lower arm 5L are collectively referred to as an upper and lower arm circuit.

[0016] The power card 6 is a DC-AC conversion unit and functions as an inverter circuit that converts the input DC power into three-phase AC of a predetermined frequency and outputs it to the motor 3. This inverter circuit also has a function of converting the AC power generated by the motor 3 into DC power. The power card 6 is provided for each of the three phases of the motor 3. The power card 6 has an upper arm 6U and a lower arm 6L connected in series with each other. The upper arm 6U and the lower arm 6L are composed of a switching element 6i and a diode 6d. The upper arm 6U and the lower arm 6L are collectively referred to as an upper and lower arm circuit.

[0017] In this embodiment, n-channel insulated-gate bipolar transistors (IGBTs) are used as the switching elements 5i and 6i that constitute each arm. IGBT is an abbreviation for Insulated Gate Bipolar Transistor. The collector electrodes of the IGBTs in the upper arms 5U and 6U are connected to the high-potential power line Hi. The emitter electrodes of the IGBTs in the lower arms 5L and 6L are connected to the low-potential power line Lo. Furthermore, the emitter electrodes of the IGBTs in the upper arms 5U and 6U and the collector electrodes of the IGBTs in the lower arms 5L and 6L are interconnected.

[0018] The filter capacitor 7a is connected between the positive and negative terminals of the DC power supply 2. The filter capacitor 7a smooths the DC current input from the DC power supply 2.

[0019] The smoothing capacitor 7b is connected between the high-potential power line Hi and the low-potential power line Lo. The smoothing capacitor 7b is connected in parallel with power cards 5 and 6. The smoothing capacitor 7b smooths the DC current boosted by the converter circuit of power card 5. The smoothing capacitor 7b stores the charge of the boosted DC voltage.

[0020] Reactor 8, in conjunction with the switching operation of power card 5, increases the input voltage to power card 5, that is, the voltage of DC power supply 2.

[0021] The control board 4 generates drive commands to operate the switching elements 5i and 6i of the power cards 5 and 6, and outputs them to a drive circuit (driver) not shown. The control board 4 generates drive commands based on torque requests input from a higher-level ECU (not shown) and signals detected by various sensors. ECU is an abbreviation for Electronic Control Unit. Specifically, the control board 4 outputs a PWM signal as a drive command. PWM is an abbreviation for Pulse Width Modulation. The control board 4 is configured to include, for example, a microcontroller (microcomputer).

[0022] The drive circuit generates a drive signal based on a drive command from the control board 4 and outputs it to the gate electrodes of the corresponding switching elements 5i and 6i on the power cards 5 and 6. This drives the switching elements 5i and 6i, i.e., turns them on and off. In this embodiment, a drive circuit is provided for each power card 5 and 6.

[0023] Next, the structure of the power converter will be described based on Figures 2 to 5. In the following description, the three directions that are orthogonal to each other will be referred to as the X direction, Y direction, and Z direction. The X direction corresponds to the stacking direction of power cards 5 and 6. The Y direction is orthogonal to the X direction and also corresponds to the direction in which the first side walls 31 of case 30 face each other. The Z direction is orthogonal to both the X and Y directions.

[0024] <Structure of a power converter> The power converter 1 comprises a case 30, a cooler 20, power cards 5 and 6, a dummy card 120, and a reactor 8. The cooler 20, power cards 5 and 6, dummy card 120, and reactor 8 are housed in the case 30.

[0025] The cooler 20 has an inlet pipe 22, an outlet pipe 23, and multiple heat exchangers 21, forming part of a circulation path for circulating liquid refrigerant. As shown in Figure 2, the multiple heat exchangers 21 are stacked in the X direction and connected to the inlet pipe 22 and outlet pipe 23 which extend in the X direction. The inlet pipe 22 and outlet pipe 23 are arranged side by side in the Y direction. Note that the arrangement of the inlet pipe 22 and outlet pipe 23 may be reversed from the arrangement shown in Figure 2. As shown in Figures 3 and 4, the inlet pipe 22 and outlet pipe 23 are located near both ends of the heat exchanger 21 in the Y direction.

[0026] The liquid refrigerant flowing in from the inlet pipe 22 flows into the heat exchanger 21. The liquid refrigerant flowing into the heat exchanger 21 flows out into the outlet pipe 23. The cooler 20 is made of a metal material with excellent thermal conductivity. The inlet pipe 22 and the outlet pipe 23 may extend in the X direction so that a portion of them is drawn out to the outside of the case 30, which will be described later.

[0027] Power cards 5 and 6 are equipped with semiconductor elements, namely switching elements 5i and 6i and diodes 5d and 6d. Multiple power cards 5 and 6 have, for example, the same structure. As shown in Figure 4, power card 5 in this embodiment further includes a main terminal 52 and a signal terminal 53, which are external connection terminals electrically connected to the switching elements 5i and 6i, and a encapsulant 51. Power card 6 has a similar configuration. In the following description, descriptions of power card 5 can be replaced with descriptions of power card 6.

[0028] The switching elements 5i and 6i are formed on a semiconductor substrate made of materials such as silicon (Si) or a wide-bandgap semiconductor with a wider bandgap than silicon. The switching elements 5i and 6i have a vertical structure so that the main current flows in the thickness direction of the semiconductor substrate. Examples of wide-bandgap semiconductors include silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), and diamond.

[0029] The external connection terminals are for electrically connecting the switching elements 5i and 6i to external devices. The main terminal 52 is electrically connected to the main electrodes of the switching elements 5i and 6i. The signal terminal 53 is electrically connected to the corresponding pads of the switching elements 5i and 6i.

[0030] The encapsulant 51 encloses some of the other elements that make up the power card 5. The remaining parts of the other elements are exposed outside the encapsulant 51. In Figure 4, the interior of the encapsulant 51 is omitted. In this embodiment, the encapsulant 51 encloses semiconductor elements such as switching elements 5i, 6i and diodes 5d, 6d, and some of the external connection terminals. As shown in Figure 4, some of the other external connection terminals protrude outside the encapsulant 51. The encapsulant 51 is made of, for example, resin. The encapsulant 51 has a substantially rectangular shape in plan.

[0031] The sealing body 51 may further have protrusions (not shown). Having protrusions allows the sealing body to be inserted by pinching the protrusions with a jig, thus improving ease of assembly.

[0032] As shown in Figure 2, multiple power cards 5 and 6 are stacked in the X direction, alternating with the heat exchangers 21. That is, the power cards 5 and 6 are positioned between adjacent heat exchangers 21. The power cards 5 and 6 and the heat exchangers 21 are in contact in the X direction via an insulator with good thermal conductivity. As a result, the power cards 5 and 6, whose temperature rises due to the heat generated by the switching elements 5i and 6i, are cooled by the heat exchangers 21 from both sides in the X direction. For example, thermal grease can be used as the insulator with good thermal conductivity. The thermal grease fills the gap between the power cards 5 and 6 and the heat exchangers 21, preventing an increase in thermal resistance.

[0033] Furthermore, the power cards 5 and 6 may be in direct contact with the heat exchanger 21 without the need for an insulator with good thermal conductivity. Also, the number of power cards 5 and 6 and their placement relative to each other are not limited by Figure 2.

[0034] The reactors 8 are stacked in the X direction, alternating with the heat exchangers 21. That is, the reactors 8 are positioned between adjacent heat exchangers 21. The reactor 8 has a core and a coil wound around the core. The orientation in which the reactors 8 are positioned is not particularly limited, but for example, they are positioned so that the axial direction of the coil is in the X direction. In this embodiment, the length of the reactor 8 in the X direction is greater than the length of the power cards 5 and 6 in the X direction. However, the length of the reactor 8 in the X direction may be equal to the length of the power cards 5 and 6 in the X direction.

[0035] The reactor 8 is in contact with the heat exchanger 21 in the X direction via an insulator with good thermal conductivity. As a result, the reactor 8 is cooled by the heat exchanger 21 from both sides in the X direction. The number of reactors 8 stacked may be one or more. The reactors 8 are stacked at one end in the X direction between multiple heat exchangers. Alternatively, the reactor 8 may be in direct contact with the heat exchanger 21 without an insulator with good thermal conductivity.

[0036] The dummy cards 120 are stacked in the X direction so as to alternate with the heat exchangers 21. That is, the dummy cards 120 are placed between adjacent heat exchangers 21. There may be one or more dummy cards. In this embodiment, one dummy card is stacked. The dummy card 120 and the heat exchanger 21 are in direct contact without anything else in between. However, there may be something interposed between the dummy card 120 and the heat exchanger 21.

[0037] The dummy card 120 is made of resin. Furthermore, the surface roughness of the dummy card 120 is greater than that of the power cards 5 and 6. For example, the surface roughness of the surface of the dummy card 120 facing the heat exchanger 21 is greater than that of the surface of the sealant 51 facing the heat exchanger 21. Surface roughness is expressed by indicators such as arithmetic mean roughness, maximum height roughness, ten-point mean roughness, and root mean square roughness. Note that the surface roughness of the dummy card 120 and the surface roughness of the power cards 5 and 6 may be the same. Also, the dummy card 120 may be made of a material other than resin, such as ceramic. It is desirable that the dummy card 120 be made of a material with low thermal conductivity.

[0038] The dummy card 120 has a stacked portion 121 and a protruding portion 122. The stacked portion 121 has substantially the same shape as the sealing body 51 of the power card 5. That is, the dummy card 120 may have further protrusions not shown. This allows it to be assembled in the same way as the power cards 5 and 6. It is desirable that the stacked portion 121 and the sealing body 51 have the same thickness in the X direction. It is also desirable that the dimensions in the Y direction and the Z direction are the same.

[0039] The stacked portion 121 is positioned to overlap with power cards 5 and 6 when viewed from the X direction. That is, the stacked portion 121 is stacked with power cards 5 and 6 in the X direction. The protruding portion 122 protrudes from the stacked portion 121 on both sides in the Y direction. The protruding portion 122 is positioned not to overlap with power cards 5 and 6 when viewed from the X direction.

[0040] In this embodiment, the thickness of the protrusion 122 in the X direction is greater than the thickness of the laminated portion 121 in the X direction. The protrusion 122 may protrude from the laminated portion 121 in the Z direction, or it may protrude in both the Y and Z directions. There may be multiple protrusions 122, or there may be just one. Furthermore, the thickness of the protrusion 122 in the X direction may be the same as the thickness of the laminated portion 121 in the X direction, or it may be thinner than the thickness of the laminated portion 121 in the X direction.

[0041] A female threaded portion 123 is formed on the protruding portion 122. In this embodiment, the female threaded portion 123 is formed on the surface of the protruding portion 122 that faces the upper wall portion 33 of the case 30, which will be described later. The female threaded portion 123 is screwed into the male threaded portion 41 of the bolt 40.

[0042] In this embodiment, the laminate 10 is formed by stacking the heat exchanger 21, power cards 5 and 6, dummy card 120, and reactor 8. In other words, the laminate 10 has the heat exchanger 21, power cards 5 and 6, dummy card 120, and reactor 8. In addition to the above, the laminate 10 may also include an inlet pipe 22 and an outlet pipe 23. A pressurizing member 140 and a support part 141 are provided at one end of the laminate 10 in the X direction, and a retaining part 142 is provided at the other end.

[0043] The pressurizing member 140 is made of, for example, a leaf spring. The pressurizing member 140 is located between the heat exchanger 21, which is located at one end of the laminate 10, and the support portion 141. The support portion 141 is integrated with the case 30 or fixed to the case 30, and serves to support the pressurizing member 140. The pressurizing member 140 is in direct or indirect contact with the heat exchanger 21, which is located at one end of the laminate 10, near its central portion.

[0044] The retaining portion 142 is integrated with or fixed to the case 30 and is in direct or indirect contact with the heat exchanger 21 located at the other end of the laminate 10. The pressurizing member 140 presses the laminate 10 toward the retaining portion 142 in the X direction. The retaining portion 142 supports the laminate 10 pressed by the pressurizing member 140. In other words, the laminate 10 is compressed in the X direction by the pressurizing member 140 and the retaining portion 142. As a result, vibration in the X direction of the laminate 10 is suppressed.

[0045] As described above, the laminate 10 is supported at both ends in the X direction. Therefore, the laminate 10 vibrates with the ends as vibration nodes. In this embodiment, the positions of the vibration nodes are the contact points between the pressurizing member 140 and the heat exchanger 21, and the contact points between the pressing part 142 and the heat exchanger 21. Furthermore, if the laminate 10 is not supported at any point other than both ends in the X direction, the vibration antinodes of the laminate 10 will be as follows. That is, if there is no bias in the X direction regarding the center of gravity of the laminate 10, the vibration antinodes will be near the center CE in the lamination direction. If there is a bias in the X direction regarding the center of gravity of the laminate 10, the vibration antinodes will move away from the center CE in the lamination direction towards the center of gravity.

[0046] Here, the central part CE in the stacking direction is the position where the number of spaces between multiple heat exchangers 21 is equal on one end and the other end in the X direction. When the number of components stacked between multiple heat exchangers 21 is odd, the central part CE in the stacking direction is where the components are placed. When the number of components stacked between multiple heat exchangers 21 is even, the central part CE in the stacking direction is where the heat exchangers 21 are placed.

[0047] The dummy card 120 is stacked on the side of the center of gravity CE in the stacking direction. In this embodiment, as described above, the reactor 8 is stacked at one end in the X direction among the multiple heat exchangers 21. The reactor 8 is heavier than the power cards 5 and 6. Therefore, the center of gravity of the stacked body 10 is biased toward the side where the reactor 8 is located, rather than the center of gravity CE in the stacking direction. In other words, in this embodiment, the dummy card 120 can also be said to be located on the side where the reactor 8 is stacked, rather than the center of gravity CE in the stacking direction.

[0048] The case 30 houses at least a portion of the elements constituting the power converter 1. In this embodiment, the case 30 houses the laminate 10 inside. The case 30 has a first side wall 31, a second side wall 32, and an upper wall 33. The first side wall 31 is located on the outside of the laminate 10 in the Y direction and is a surface that aligns with the XZ plane. The second side wall 32 is located on the outside of the laminate 10 in the X direction and is a surface that aligns with the YZ plane. The upper wall 33 is a surface that aligns with the XY plane.

[0049] A portion of the upper wall portion 33 is open in the Z direction. At least a portion of the upper wall portion 33 faces at least a portion of the protruding portion 122 in the Z direction. As shown in Figure 4, in this embodiment, the length of the opening in the Y direction is greater than the length of the signal terminal 53 in the Y direction. As a result, the signal terminal 53 of the power card 5 is connected to an external device through the opening. Note that the arrangement of the main terminal 52 and the signal terminal 53 may be reversed from that in Figure 4. That is, the main terminal 52 may be connected to an external device through the opening.

[0050] In this embodiment, the upper wall portion 33 has a through hole 34 that penetrates in the Z direction. The through hole 34 is an elongated hole extending in the X direction. When viewed from the Z direction, at least a portion of the through hole 34 overlaps with the aforementioned female thread portion 123. In this embodiment, when viewed from the Z direction, the entire female thread portion 123 overlaps with at least a portion of the through hole 34. The bolt 40 is screwed into the female thread portion 123 with the bolt passing through the through hole 34 in the Z direction. That is, the dummy card 120 is fixed to the case 30 in the Z direction by the bolt 40.

[0051] The number of through holes 34 may be multiple or one. It is desirable that the number of bolts 40, female threaded portions 123, and through holes 34 be equal. In this embodiment, there are two bolts 40, two female threaded portions 123, and two through holes 34, and one dummy card is fixed in two places.

[0052] The through hole 34 may be provided in the first side wall portion 31. The through hole 34 is an elongated hole extending in the X direction. In this case, the female thread portion 123 is provided on the surface of the dummy card 120 facing the first side wall portion 31. In particular, it is desirable that the female thread portion 123 be provided on the surface of the protruding portion 122 facing the first side wall portion 31. The positions of the through hole 34 and the female thread portion 123 in the Z direction are substantially the same. That is, as shown in Figure 5, the bolt 40 may be screwed into the female thread portion 123 with the bolt passing through the through hole 34 in the Y direction. In other words, the dummy card 120 may be fixed to the case 30 in the Y direction by the bolt 40.

[0053] <Effects and Effects in the First Embodiment> The power converter 1 according to this embodiment has the following structure for the laminate 10 in which power cards 5, 6 and heat exchangers 21 are stacked. That is, at least one of the locations between the multiple heat exchangers 21 is stacked in place of the power cards 5, 6, and fixed to the case 30. With this structure, the location where the dummy card 120 is stacked can be selected from among the multiple heat exchangers 21, that is, the dummy card 120 can be placed in a location close to the antinode of vibration in the stacking direction (X direction) and fixed to the case 30. In other words, since the location with a large amplitude can be fixed to the case, the vibration resistance of the laminate 10 can be improved.

[0054] The effects described above can also be explained as follows. When the power converter 1 is mounted on a vehicle, the input vibrations to the power converter 1 are predominant in the low-frequency range, and smaller in the high-frequency range. In other words, increasing the natural frequency of the laminate 10 leads to improved vibration resistance. And to increase the natural frequency, it is effective to fix the part close to the antinode of the vibration. As mentioned above, according to the structure of this embodiment, a dummy card 120 can be placed in the part close to the antinode of the vibration and fixed to the case 30. Therefore, it is possible to increase the natural frequency and improve the vibration resistance of the laminate 10.

[0055] Furthermore, in this embodiment, the dummy card 120 is fixed in place. The dummy card 120 does not contain the semiconductor switching elements 5i, 5i. That is, it does not generate heat and therefore does not require cooling. Consequently, in the case of the dummy card 120, there is no need for measures to improve heat transfer, such as applying thermal grease between it and the heat exchanger 21.

[0056] Contrary to this embodiment, when fixing heat-generating components, the following problems are likely to occur. Specifically, if thermal grease or the like is applied to the fixed component to improve heat transfer, the coefficient of friction between the fixed component and the heat exchanger 21 decreases. As a result, it becomes easier to slide in the direction perpendicular to the stacking direction (X direction), and the effect of suppressing vibration is reduced. In contrast, in this embodiment, the application of thermal grease or the like is unnecessary, so vibration resistance can be improved.

[0057] Furthermore, in this embodiment, the reactor 8 is also stacked together with the power cards 5 and 6. Therefore, the reactor 8 can be efficiently cooled by the heat exchanger 21. Also, as mentioned above, the reactor 8 is generally heavier than the power cards 5 and 6. Therefore, when the reactor 8 is stacked, the center of gravity of the stacked body 10 in the stacking direction (X direction) tends to be uneven. Since the position of the antinodes of vibration is also affected by the unevenness of the center of gravity, the above-mentioned effect of being able to select and fix a location close to the antinode is suitably demonstrated.

[0058] Furthermore, in this embodiment, the dummy card 120 is stacked on the side of the center of gravity CE in the stacking direction and fixed to the case 30. As mentioned above, when heavy reactors 8 are stacked, the center of gravity of the stacked body 10 in the stacking direction (X direction) tends to be biased. In such cases, the position of the vibration antinode will be biased towards the center of gravity CE in the stacking direction. According to the structure of this disclosure, even if the center of gravity in the stacking direction is biased, the dummy card 120 can be placed near the vibration antinode and fixed to the case 30. In other words, since the area with a large amplitude can be fixed to the case 30, the vibration resistance of the stacked body 10 can be improved.

[0059] Furthermore, in this embodiment, the dummy card 120 is fixed to the case 30 by bolts 40. The through-holes 34 provided in the case 30, through which the bolts 40 pass, are elongated holes that extend along the stacking direction (X direction) of the power cards 5 and 6. This allows the dummy card 120 to be fixed to the case 30 while absorbing the dimensional tolerances of the stacked body 10 in the stacking direction (X direction). Thus, the workability of assembly is improved.

[0060] Furthermore, in this embodiment, the dummy card 120 has a stacked portion 121 and a protruding portion 122, and the protruding portion 122 is fixed to the case 30 by a bolt 40. Contrary to this structure, if the fixing point that secures the dummy card 120 to the case 30 is located in the stacked portion 121, the following problems will occur. That is, considering the miniaturization of the stacked body 10 in the stacking direction, it is difficult to secure a sufficient size for the stacked portion 121 in the stacking direction (X direction). Therefore, the diameter of the bolt 40 and the fixing point are constrained by the length in the stacking direction (X direction).

[0061] In contrast, in the structure of this disclosure, the dummy card 120 has a protrusion 122, and the protrusion 122 is fixed to the case 30 by a bolt 40. Therefore, the diameter of the bolt 40 and the fixing point can be made sufficiently large without impairing the miniaturization of the laminate in the stacking direction (X direction).

[0062] Furthermore, in this embodiment, the surface roughness of the dummy card 120 is greater than that of the power cards 5 and 6. As mentioned above, the dummy card 120 does not contain any semiconductor elements and therefore does not need to be cooled. For this reason, in order to efficiently cool the power cards 5 and 6, it is effective to reduce the amount of heat transferred between the dummy card 120 and the heat exchanger 21. According to the structure of this disclosure, the contact area between the dummy card 120 and the heat exchanger 21 is reduced, so the amount of heat transferred can be reduced. This allows the power cards 5 and 6 to be cooled efficiently.

[0063] (Second Embodiment) In the first embodiment described above, the dummy card has a protrusion 122, which is fixed to the case 30 by a bolt 40. In contrast, in this embodiment, the stacked portion 121 and the upper wall portion 33 face each other in the Z direction. The stacked portion 121 is provided with a female screw portion 123. Furthermore, a through hole 34 is provided in the upper wall portion 33 at a position opposite the female screw portion 123 in the Z direction. That is, as shown in Figure 7, the stacked portion 121 is fixed to the case 30 in the Z direction by a bolt 40. In other words, as shown in Figure 6, the location where the dummy card 120 is fixed is located inside the Y-direction ends of the power cards 5 and 6.

[0064] In this case, the protruding portion 122 may or may not be present, as shown in Figure 7. Furthermore, at least the following portion of the upper wall portion 33 has an opening. That is, the portion of the upper wall portion facing the Z-direction from the location where the power cards 5 and 6 are placed has an opening.

[0065] In this embodiment as well, dummy cards 120 can be placed in the portion of the stacking direction (X direction) that is close to the antinode of vibration and fixed to the case 30. In other words, since the portion with the largest amplitude can be fixed to the case 30, the vibration resistance of the stacked body 10 can be improved.

[0066] (Third embodiment) In this embodiment shown in Figure 8, the upper wall portion 33 has a female threaded portion 36, and the dummy card 120 has a through hole 125. The female threaded portion 36 and the through hole 125 are opposite each other. The dummy card 120 is fixed to the case 30 by screwing the bolt 40 into the female threaded portion 36 with the bolt passing through the through hole 125. The through hole 125 may be formed in the protruding portion 122 of the dummy card 120, as shown in Figure 8, or it may be formed in the stacked portion 121.

[0067] This embodiment also improves the vibration resistance of the laminate 10.

[0068] (Fourth Embodiment) In this embodiment shown in Figure 9, the dummy card 120 is fixed to the case 30 by adhesive 70. Specifically, the dummy card 120 is fixed to the upper wall portion 33 with adhesive 70. This embodiment also improves the vibration resistance of the laminate 10. Furthermore, since bolts 40 and the like are not required, the number of necessary parts can be reduced.

[0069] (Fifth embodiment) In this embodiment shown in Figure 10, the dummy card 120 is provided with a protrusion 124. Furthermore, the case 30 is provided with a recess 35. The protrusion 124 and the recess 35 have substantially the same shape. The shapes of the protrusion 124 and the recess 35 are not particularly limited, but for example, they are cylindrical. In this case, the diameter of the protrusion 124 is slightly larger than the diameter of the recess 35. The protrusion 124 is then press-fitted into the recess 35 with plastic deformation. That is, the dummy card 120 is fixed to the case 30 by the press-fitting of the protrusion 124 into the recess 35. The number of protrusions and recesses is not particularly limited, but it is desirable that the number of protrusions and recesses be equal.

[0070] Note that the locations of the protrusion 124 and the recess 35 are not limited by Figure 10 as long as they are in positions opposite to each other. That is, the protrusion 124 may be provided on the surface of the stacked portion 121 that is opposite to the upper wall portion 33, as shown in Figure 10. Alternatively, the dummy card 120 may have a protrusion 122, and the protrusion 122 may be provided on the surface of the protrusion 122 that is opposite to the upper wall portion 33, or on the surface that is opposite to the first side wall portion 31. The recess 35 is provided on the case 30 in a location opposite to the protrusion 124 so as to fit with the protrusion 124.

[0071] This embodiment also improves the vibration resistance of the laminate 10. Furthermore, since bolts 40 and the like are not required, the number of necessary parts is reduced, thereby lowering costs.

[0072] (Sixth Embodiment) In this embodiment shown in Figure 11, the reactor 8 is not stacked. That is, the stacked body 10 is formed by stacking the heat exchanger 21, power cards 5 and 6, and dummy card 120. Furthermore, as shown in Figure 11, the difference between the number of power cards 5 and 6 located on one side of the stacking direction (X direction) relative to the dummy card 120 and the number of power cards 5 and 6 located on the other side is zero. In this embodiment, the total number of power cards 5 and 6 is even, but it may be odd. If it is odd, the difference between the power cards 5 and 6 located on one side of the stacking direction (X direction) relative to the dummy card 120 and the other side is 1.

[0073] The position in which the dummy cards 120 are stacked can also be described as follows: Among the multiple heat exchangers 21, the dummy cards 120 are stacked at a position that overlaps with the central part CE in the stacking direction, or at the position closest to the central part CE in the stacking direction. In other words, if the total number of power cards 5, 6 and dummy cards 120 is odd, the dummy cards 120 are stacked at a position that overlaps with the central part CE in the stacking direction. If the total number of power cards 5, 6 and dummy cards 120 is even, the dummy cards 120 are stacked at a position adjacent to the heat exchanger 21 located at the central part CE in the stacking direction. The dummy cards 120 are then fixed to the case 30.

[0074] Furthermore, the position in which the dummy card 120 is stacked may be as follows: The dummy card 120 may be stacked at the position closest to the point in the X direction where the distance from both ends of the stack 10 is equal among the multiple heat exchangers 21. In this embodiment, both ends of the stack 10 refer to the contact points between the pressurizing member 140 and the heat exchanger 21, and the contact points between the pressing part 142 and the heat exchanger 21. In this embodiment, the thickness of the power cards 5 and 6 in the X direction is all approximately the same. Also, the thickness of the multiple heat exchangers 21 in the X direction is also approximately the same. Therefore, in this embodiment, the above position is the same as the central part CE in the stacking direction.

[0075] In this embodiment, the laminate 10 is fixed to the case 30 at the point closest to the center CE in the stacking direction. Here, if there is no bias in the X direction regarding the center of gravity of the laminate 10, the antinode of vibration will be near the center CE in the stacking direction. Therefore, the laminate 10 can be fixed at a position close to the antinode of vibration, thereby improving the reliability of vibration suppression.

[0076] (Seventh Embodiment) In the embodiment shown in Figures 12 and 13, at least one of the power cards 5 and 6 is fixed to the case 30. As shown in Figure 13, the fixed power cards 5 and 6 have a sealing projection 54, and a female threaded portion 55 is provided on the sealing projection 54. The sealing body 51 is fixed to the case 30 by screwing a bolt 40 through the case 30 into the female threaded portion 55. Note that the interior of the sealing body 51 is omitted in Figure 13.

[0077] In this embodiment, as in the first embodiment, the reactor 8 is stacked at one end in the X direction between the multiple heat exchangers. The power cards 5 and 6, which are fixed to the case 30, are stacked on the side of the center of gravity CE in the stacking direction.

[0078] According to this embodiment, power cards 5 and 6 located near the antinodes of vibrations in the stacking direction (X direction) can be selected and fixed to the case 30. In other words, even with this embodiment, the areas with large amplitudes can be fixed to the case 30, thereby improving the vibration resistance of the laminate 10. Furthermore, power cards 5 and 6, which have switching functions, are fixed to the case 30, rather than just components that only have a fixing function. Therefore, the stacking of components that only have a fixing function, such as dummy cards 120, becomes unnecessary, and the increase in the size in the stacking direction can be suppressed.

[0079] (Other embodiments) The disclosure in this specification is not limited to the exemplary embodiments. The disclosure encompasses the exemplary embodiments and variations thereof by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and elements shown in the embodiments, but can be implemented in various variations. The disclosure can be implemented in a variety of combinations. The disclosure may have additional parts that can be added to the embodiments. The disclosure encompasses embodiments in which parts and elements have been omitted. The disclosure encompasses substitutions or combinations of parts and elements between one embodiment and another. The scope of the disclosed technical field is not limited to the descriptions of the embodiments. The scope of the disclosed technical field is indicated by the claims and should be understood to include all modifications within the meaning and scope equivalent to the claims.

[0080] Spatially relative terms such as “inside,” “outside,” “top,” and “bottom” are used here to facilitate descriptions of the relationship between one element or feature and other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, if the device in the drawing is turned upside down, an element described as “top” of another element or feature will be oriented “bottom” of the other element or feature. Therefore, the term “top” can encompass both top and bottom orientations. The device may also be oriented in other directions (it may be rotated 90 degrees or in other directions), and the spatially relative descriptors used in this specification will be interpreted accordingly.

[0081] In the above embodiment, power cards 5 and 6 and reactor 8 are stacked as electrical components, but other heat-generating electrical components may also be stacked. That is, the stacked body 10 may have other electrical components. For example, capacitors 7a and 7b may be stacked. The number of stacked capacitors 7a and 7b may be multiple or just one. In this case, the capacitors 7a and 7b are stacked in the X direction so as to alternate with the heat exchanger 21. The positions in which the capacitors 7a and 7b are placed are not particularly limited, but for example, they may be stacked in positions adjacent to the power cards 5 and 6 via the heat exchanger 21.

[0082] With the above structure, electrical components other than the power cards 5 and 6 and the reactor 8, such as capacitors 7a and 7b, can be efficiently cooled from both sides in the X direction by the heat exchanger 21.

[0083] Furthermore, in the above embodiment, the dummy card 120 is stacked on the side of the center of gravity from the central part CE in the stacking direction, but it may also be placed in the locations described below. That is, it may be placed in a location shifted towards the center of gravity from the point where the distance from both ends of the stacked body 10 is equal in the X direction. The ends of the stacked body 10 refer to the contact points between the pressurizing member 140 and the heat exchanger 21, and the contact points between the pressing part 142 and the heat exchanger 21. In this case as well, the dummy card 120 can be stacked and fixed to the case 30 at a location close to the antinode of vibration. Thus, vibration resistance can be improved.

[0084] In the above embodiment, the laminate 10 has both a converter circuit and an inverter circuit, but it may have only one of them. That is, the laminate 10 may have only one of the power card 5 and the power card 6.

[0085] (Disclosure of technical ideas) This specification discloses several technical concepts, as listed in the following paragraphs. Some paragraphs are written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs are written in a multiple dependent form, referring to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical concepts.

[0086] (Technical thought 1) Multiple power cards (5, 6) are arranged in a stack, each containing semiconductor elements (5i, 6i, 5d, 6d) that convert power through switching operation and are sealed in resin. A dummy card (120) that does not contain the aforementioned semiconductor element, Multiple heat exchangers (21) are stacked between the multiple power cards to cool the power cards, The system comprises the power card, the dummy card, and a case (30) that houses the heat exchanger, At least one of the multiple heat exchangers is arranged in a stack of dummy cards in place of the power cards. The dummy card is fixed to the case, and the device is a power converter.

[0087] (Technical thought 2) The system includes a reactor (8) that boosts the input voltage to the power card, The power conversion device according to technical concept 1, wherein the reactor is stacked together with the power card and cooled by the heat exchanger.

[0088] (Technical Thought 3) A bolt (40) having a male threaded portion (41), A female screw portion (123) is formed on either the dummy card or the case and is screwed into the male screw portion, The dummy card and the other part of the case have through holes (34) formed in them, The bolt secures the dummy card to the case by being screwed into the female threaded portion while passing through the through hole. The power conversion device according to technical concept 1 or 2, wherein the through-hole is an elongated hole extending along the stacking direction of the power card.

[0089] (Technical Thought 4) The dummy card has a stacked portion (121) which is a part stacked on the heat exchanger, and a protruding portion (122) which protrudes from the stacked portion in a direction perpendicular to the stacking direction, The bolt fixes the protruding portion to the case, as described in technical concept 3 of the power conversion device.

[0090] (Technical Thought 5) A power conversion device according to technical idea 1 or 2, wherein the dummy card is fixed to the case with adhesive (70).

[0091] (Technical Thought 6) The dummy card and the case have a protrusion (124) on one of them, The dummy card and the other of the case have a recess (35), The dummy card is fixed to the case by press-fitting the convex portion into the concave portion, as described in technical concept 1 or 2.

[0092] (Technical Thought 7) A power conversion device according to any one of technical ideas 1 to 6, wherein the difference between the number of power cards located on one side of the stacking direction of the power cards relative to the dummy card and the number of power cards located on the other side is 1 or zero.

[0093] (Technical Thought 8) The position where the number of spaces between the multiple heat exchangers is equal on one side and the other side in the stacking direction of the power card is defined as the center portion (CE) in the stacking direction. A power conversion device according to any one of technical concepts 1 to 6, wherein the dummy cards are stacked on the side of the center of gravity rather than the center in the stacking direction.

[0094] (Technical Thought 9) A power conversion device according to any one of Technical Concepts 1 to 8, wherein the surface roughness of the surface of the dummy card facing the heat exchanger is greater than the surface roughness of the surface of the power card facing the heat exchanger.

[0095] (Technical Thought 10) Multiple power cards (5,6) are arranged in a stack, each containing semiconductor elements (5i,6i,5d,6d) that convert power through switching operation, which are sealed in resin. Multiple heat exchangers (21) are stacked between the multiple power cards to cool the power cards, The system comprises a case (30) housing the power card and the heat exchanger, A power converter in which at least one of the multiple power cards is fixed to the case.

[0096] (Technical Thought 11) The system includes a reactor (8) that boosts the input voltage to the power card, The reactor is stacked together with the power card and cooled by the heat exchanger. The position where the number of spaces between the multiple heat exchangers is equal on one side and the other side in the stacking direction of the power card is defined as the center portion (CE) in the stacking direction. The power conversion device according to technical concept 10, wherein the power cards are stacked on the side of the center of gravity that is closer to the center of gravity than the center of the stacking direction, and are fixed to the case. [Explanation of Symbols]

[0097] 5...Power card, 5d...Diode (semiconductor element), 5i...Switching element (semiconductor element), 6...Power card, 6d...Diode (semiconductor element), 6i...Switching element (semiconductor element), 8...Reactor, 21...Heat exchanger, 30...Case, 34...Through hole, 35...Recess, 40...Bolt, 41...Male threaded part, 70...Adhesive, 120...Dummy card, 121...Laminated part, 122...Protruding part, 123...Female threaded part, 124...Convex part, CE...Center in the lamination direction

Claims

1. Multiple power cards (5, 6) arranged in a stack, each containing semiconductor elements (5i, 6i, 5d, 6d) that convert power through switching operation and are sealed in resin, A dummy card (120) that does not contain the aforementioned semiconductor element, Multiple heat exchangers (21) are stacked between the multiple power cards to cool the power cards, The system comprises the power card, the dummy card, and a case (30) that houses the heat exchanger, At least one of the multiple heat exchangers is arranged in a stack of dummy cards in place of the power cards. The dummy card is fixed to the case, and the device is a power converter.

2. The system includes a reactor (8) that boosts the input voltage to the power card, The power conversion device according to claim 1, wherein the reactor is stacked together with the power card and cooled by the heat exchanger.

3. A bolt (40) having a male threaded portion (41), A female screw portion (123) is formed on either the dummy card or the case and is screwed into the male screw portion, The dummy card and the case have through holes (34) formed in the other, The bolt secures the dummy card to the case by being screwed into the female threaded portion while passing through the through hole. The power conversion device according to claim 1 or 2, wherein the through hole is an elongated hole extending along the stacking direction of the power card.

4. The dummy card has a stacked portion (121) which is a part stacked on the heat exchanger, and a protruding portion (122) which protrudes from the stacked portion in a direction perpendicular to the stacking direction. The power conversion device according to claim 3, wherein the bolt fixes the protruding portion to the case.

5. The power conversion device according to claim 1 or 2, wherein the dummy card is fixed to the case with adhesive (70).

6. The dummy card and the case have a protrusion (124) on one of them, The dummy card and the other of the case have a recess (35), The power conversion device according to claim 1 or 2, wherein the dummy card is fixed to the case by press-fitting the convex portion into the concave portion.

7. The power conversion device according to claim 1 or 2, wherein the difference between the number of power cards located on one side of the stacking direction of the power cards relative to the dummy card and the number of power cards located on the other side is 1 or zero.

8. The position where the number of spaces between the multiple heat exchangers is equal on one side and the other side in the stacking direction of the power card is defined as the center portion (CE) in the stacking direction. The power conversion device according to claim 1 or 2, wherein the dummy cards are stacked on the side of the center of gravity rather than the center in the stacking direction.

9. The power conversion device according to claim 1 or 2, wherein the surface roughness of the dummy card facing the heat exchanger is greater than the surface roughness of the power card facing the heat exchanger.

10. Multiple power cards (5, 6) arranged in a stack, each containing semiconductor elements (5i, 6i, 5d, 6d) that convert power through switching operation and are sealed in resin, Multiple heat exchangers (21) are stacked between the multiple power cards to cool the power cards, The system comprises a case (30) housing the power card and the heat exchanger, A power converter in which at least one of the multiple power cards is fixed to the case.

11. The system includes a reactor (8) that boosts the input voltage to the power card, The reactor is stacked together with the power card and cooled by the heat exchanger. The position where the number of spaces between the multiple heat exchangers is equal on one side and the other side in the stacking direction of the power card is defined as the center portion (CE) in the stacking direction. The power conversion device according to claim 10, wherein the power cards are stacked on the side of the center of gravity that is closer to the center of gravity than the center of the stacking direction.

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