JP2015119536A - Power conversion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibration of a transaxle or the like even when the vibration is transmitted to a case storing power modules, and to suppress generation of thermal strain on a control substrate fixed in the case.SOLUTION: A lamination unit in which a plurality of power modules and a plurality of coolant passages are laminated is stored in a case 20. A control substrate 50 is mounted on a mounting face 24 of the case 20 through a resin fixing member 60 and connected to the power modules by signal lines. A linear expansion coefficient of the fixing member 60 is a value closer to a linear expansion coefficient of the control substrate 50 rather than a linear expansion coefficient of the case 20. The fixing member 60 includes first fixing portions 64 for fixing the control substrate on the fixing member 60 and second fixing portions 60 for fixing the fixing member 60 in the case 20. The first fixing portions 64 and the second fixing portions 66 are arranged on respectively different positions in the fixing member 60.

Description

  The present invention relates to a power conversion device used in an automobile.

  A voltage conversion circuit such as a converter circuit or an inverter circuit is used to generate drive power supplied to a drive motor that is a power source of an electric vehicle or a hybrid vehicle, for example.

  Generally, in an electric vehicle and a hybrid vehicle, a large amount of driving power is required to secure a large driving torque from the driving motor. Therefore, in a power conversion circuit that generates drive power for a drive motor, heat generated from a power module including a switching element such as an IGBT that constitutes the power conversion circuit tends to increase. Therefore, a power conversion device has been proposed in which a plurality of refrigerant flow paths through which a refrigerant flows are stacked with a power module so that the plurality of power modules constituting the power conversion circuit can be cooled.

  Patent Document 1 discloses a power conversion device including a unit in which a plurality of power modules and a plurality of refrigerant channels are stacked, and a metal bracket that supports the unit in a case. Further, Patent Documents 2 and 3 disclose electric power including a unit in which a plurality of power modules and a plurality of refrigerant flow paths are stacked, a frame that holds the unit, and a lid plate that closes an opening of the frame. A conversion device is disclosed.

JP2013-51848A JP 2012-231591 A JP 2012-217315 A

  By the way, when using a laminated unit in which a plurality of power modules and a plurality of refrigerant flow paths are laminated, increasing the number of power modules can increase the output relatively easily while suppressing an increase in the size of the housing. It becomes possible. In addition, from the viewpoint of effective use of space in the engine room, a laminated unit may be mounted on the transaxle.

  However, when the number of power modules is increased, the mass of the laminated unit is increased and the resonance frequency of the laminated unit is lowered. In addition, as the number of power modules increases, it is necessary to increase the size of the control board that controls the power modules, and the resonance frequency of the control board also decreases as the size of the control board increases. Such a decrease in the resonance frequency leads to an increase in vibration amplitude. A control board or the like connected to the power module is fixed to the case that accommodates the laminated unit, and an increase in the amplitude increases distortion generated in the control board and the like, thereby reducing reliability of strength against vibration. There's a problem. In particular, when a laminated unit is mounted on a transaxle, vibration from the engine or road surface is more easily transmitted to the laminated unit than when a laminated unit is mounted on the body of an automobile. It becomes easy to generate | occur | produce a distortion and a crack in components.

  In order to suppress the vibration of the laminated unit, it is effective to increase the rigidity of the case that houses the laminated unit. However, if the control board is fixed to the case and the case is made rigid, thermal distortion caused by the difference in coefficient of linear expansion between the control board and the aluminum case occurs at high or low temperatures. There is a problem that solder cracks are likely to occur.

  An object of the present invention is to suppress the vibration of a transaxle or the like even when transmitted to a case housing a power module, and to suppress the occurrence of thermal distortion in a control board fixed to the case. That is.

  The invention according to claim 1 houses a laminated unit in which a plurality of power modules including a switching element for power conversion, a plurality of refrigerant flow paths through which a refrigerant for cooling the power module flows, and the laminated unit. A case, a resin fixing member fixed to the outer surface of the case, a control fixed to the fixing member and attached to the case via the fixing member, and connected to the plurality of power modules A board, a first fixing part for fixing the control board to the fixing member, and a second fixing part for fixing the fixing member to the case, and the linear expansion coefficient of the fixing member is The linear expansion coefficient is closer to the linear expansion coefficient of the control board, and the first fixing part and the second fixing part are arranged at different positions in the fixing member. An electric power converter according to.

  According to the present invention, since the control board is fixed to the case by the resin-made fixing member having a high vibration damping capability, the case and the control board are integrated even when vibration such as a transaxle is transmitted to the case. Thus, vibration can be suppressed. Further, the linear expansion coefficient of the fixing member is closer to the linear expansion coefficient of the control board than the linear expansion coefficient of the case, and the first fixing portion and the second fixing portion are arranged at different positions on the fixing member. Therefore, it can suppress that the thermal strain of a case is transmitted to a control board, and can suppress generation | occurrence | production of the thermal strain in a control board.

It is a perspective view showing an example of a power converter concerning an embodiment of the present invention. It is a perspective view which shows an example of the case of the power converter device which concerns on this embodiment. It is a perspective view which shows an example of the fixing member which concerns on this embodiment. It is AA sectional drawing of the power converter device which concerns on this embodiment. It is BB sectional drawing of the power converter device which concerns on this embodiment. It is AA sectional drawing of the power converter device which concerns on the comparative example 1. FIG. It is BB sectional drawing of the power converter device which concerns on the comparative example 1. FIG. It is AA sectional drawing of the power converter device which concerns on the comparative example 2. FIG. It is BB sectional drawing of the power converter device which concerns on the comparative example 2. FIG.

  With reference to FIGS. 1-5, the power converter device which concerns on this embodiment is demonstrated. As shown in FIG. 1, a power conversion device 10 according to this embodiment includes a laminated unit (not shown) in which a plurality of power modules and a plurality of refrigerant channels are laminated, and a metal (for example, aluminum) that houses the laminated unit. A control board 50 connected to a plurality of power modules, and a resin-made fixing member 60 for attaching the control board 50 to the case 20. . The laminated unit is fixed to the case 20 in the case 20. The case 20 may be stacked on another component.

  As shown in FIG. 2, the case 20 has a mounting surface 24 to which the fixing member 60 is fixed. A control board 50 is attached to the attachment surface 24 via a fixing member 60. The mounting surface 24 has an opening for passing the signal line 36 connecting the power module in the case 20 and the control board 50.

  As shown in FIG. 3, the fixing member 60 has a flat plate shape and is formed with an opening 62 through which the signal line 36 connecting the control board 50 and the power module in the case 20 passes. The fixing member 60 includes a plurality of first fixing portions 64 for fixing the control board 50 to the fixing member 60 and a plurality of second fixing portions for fixing the fixing member 60 to the mounting surface 24 of the case 20. 66 are provided. Screw holes and through holes are formed in the first fixing portion 64 and the second fixing portion 66 in the thickness direction of the fixing member 60. The first fixing part 64 and the second fixing part 66 are arranged at different positions in the fixing member 60.

  In the present embodiment, the linear expansion coefficient of the fixing member 60 is closer to the linear expansion coefficient of the base material of the control board 50 than the linear expansion coefficient of the case 20. As an example, the linear expansion coefficient of the case 20 is 21.0 (ppm / ° C.), the linear expansion coefficient of the base material of the control substrate 50 is 12.0 (ppm / ° C.), and the linear expansion coefficient of the fixing member 60 is Is a value close to the linear expansion coefficient of the base material of the control board 50 (for example, 12.0 to 16.5 (ppm / ° C.)) between 12.0 and 21.0 (ppm / ° C.). .

  As shown in FIG. 1, a through hole 52 is formed in the control board 50 at a position corresponding to the first fixing portion 64 of the fixing member 60. The mounting surface 24 of the case 20 is provided with a support portion in which a screw hole is formed at a position corresponding to the through hole of the second fixing portion 66 of the fixing member 60.

  Then, as shown in FIG. 1, the screw member 70 is passed through the through hole 52 of the control board 50 and the screw hole of the first fixing portion 64 of the fixing member 60, and the control board 50 is connected to the fixing member 60 by the screw member 70. Fix it. Further, a screw member different from the screw member 70 is passed through the through hole of the second fixing portion 66 of the fixing member 60 and the screw hole of the support portion (not shown) provided on the mounting surface 24 of the case 20. The fixing member 60 is fixed to the mounting surface 24 of the case 20 with the other screw member. In this way, the control board 50 is attached to the attachment surface 24 of the case 20 via the fixing member 60.

  Here, with reference to FIG. 4, the laminated unit installed in the case 20 will be described. 4 is a cross-sectional view taken along line AA in FIG. FIG. 4 shows a state in which the control board 50 is attached to the case 20 via the fixing member 60. In the case 20, a laminated unit 30 in which a plurality of flat power modules 32 and a plurality of flat refrigerant channels 34 are alternately laminated is installed. The laminated unit 30 is fixed to the attachment portion 22 of the case 20. As shown in the figure, it is preferable that the laminated unit 30 is urged and fixed in the laminating direction by the spring member 28. The fixing member 60 is supported by a support portion 26 that extends upward from the mounting surface 24. A screw hole is formed in the support portion 26, and the fixing member 60 is fixed to the mounting surface 24 by the screw hole and the screw member.

  The power module 32 has a built-in switching element. The power module 32 and the control board 50 are connected by a signal line 36. The control board 50 controls ON / OFF of the switching element. A refrigerant that cools the power module 32 flows through the refrigerant flow path 34. A unit 40 including a reactor and a capacitor is installed in the case 20. For example, the switching element, the reactor, and the capacitor in the power module 32 constitute a power conversion circuit such as a converter that converts the battery voltage and an inverter that converts direct current to alternating current.

  Further, as an example, two pipes (not shown) pass through the plurality of refrigerant channels 34 and support the plurality of refrigerant channels 34 so that they are arranged in parallel. The two pipes and each refrigerant flow path 34 communicate with each other, and the refrigerant (for example, water) supplied from one pipe passes through each refrigerant flow path 34 and is discharged from the other pipe. The power module 32 incorporating the switching element is sandwiched between two adjacent refrigerant flow paths 34. In the laminated unit 30, since the refrigerant passes through both surfaces of the flat power module 32, the switching element can be efficiently cooled.

  Next, with reference to FIG.4 and FIG.5, the vibration suppression and thermal distortion suppression effect of the power converter device 10 are demonstrated. FIG. 5 is a cross-sectional view taken along the line BB of FIG. FIG. 5 shows a state in which the control board 50 is attached to the case 20 via the fixing member 60.

  For example, when vibration from the engine or road surface is transmitted to the case 20, as shown in FIG. 4, the laminated unit 30 fixed to the case 20 vibrates in the vertical direction (X direction). At this time, resonance occurs at a resonance frequency determined by the mass of the laminated unit 30, and the amplitude of vibration increases. In this embodiment, since the control board 50 is fixed to the case 20 by the resin fixing member 60 having higher vibration damping capability than the case 20, the fixing member 60 exhibits a damping effect during resonance, and the laminated unit 30. Suppresses vertical vibrations. As a result, it is possible to prevent damage to components (for example, the connection portion of the refrigerant flow path 34 and the signal line 36) due to vibration.

  Further, at a high temperature, as shown in FIG. 5, the case 20 thermally expands in the lateral direction (Y direction). In the present embodiment, since the fixing member 60 is directly fixed to the case 20, when the case 20 is thermally expanded, thermal strain due to a difference in linear expansion coefficient from the case 20 is generated in the fixing member 60. However, the control board 50 is attached to the case 20 via a fixing member 60 having a linear expansion coefficient that is close, and the control board 50 and the fixing member 60 are not fixed to the case 20 by fastening together. Since the first fixing part 64 and the second fixing part 66 are arranged at different positions, the structure is such that the thermal strain of the case 20 is difficult to transmit to the control board 50. Therefore, it is possible to suppress the occurrence of thermal distortion in the control substrate 50 and suppress the occurrence of solder cracks.

  Next, Comparative Examples 1 and 2 will be described. 6 and 7 show a power converter according to Comparative Example 1, and FIGS. 8 and 9 show a power converter according to Comparative Example 2. FIG. 6 and 8 are cross-sectional views corresponding to FIG. 4, and FIGS. 7 and 9 are cross-sectional views corresponding to FIG.

  In Comparative Example 1, as shown in FIGS. 6 and 7, the control board 50 is directly fixed to the mounting surface 24 of the case 20. Unlike the present embodiment, Comparative Example 1 is not provided with a member that suppresses vibration during resonance. Therefore, as shown in FIG. 6, when the laminated unit 30 vibrates in the vertical direction (X direction) due to resonance, the vibration is not suppressed, and the vibration causes components such as the connection portion of the refrigerant flow path 34 and the signal line 36. May be distorted and the parts may be damaged. Further, as shown in FIG. 7, when the case 20 expands in the lateral direction (Y direction) at a high temperature, thermal distortion due to a difference in linear expansion coefficient between the control board 50 and the case 20 occurs, and the control board 50 Solder cracks may occur.

  Compared to Comparative Example 1, Comparative Example 2 is a case in which the rigidity of the case 20 is reinforced. Also in the comparative example 2, as shown in FIGS. 8 and 9, the control board 50 is directly fixed to the mounting surface 24 of the case 20. In Comparative Example 2, the thickness of the attachment portion 22 is thicker than that of Comparative Example 1 in order to enhance the rigidity of the case 20. As described above, by increasing the thickness of the attachment portion 22, the amplitude of vibration of the stacked unit 30 fixed to the attachment portion 22 is reduced. However, when the rigidity of the case 20 is increased, thermal strain due to the difference in linear expansion coefficient between the control board 50 and the case 20 increases at high temperatures, and solder cracks are likely to occur in the control board 50.

  On the other hand, in this embodiment, by attaching the control board 50 to the case 20 via the fixing member 60, as described above, the occurrence of thermal distortion in the control board 50 is suppressed while suppressing the vibration of the stacked unit 30. Can be suppressed. Therefore, for example, in the case where the number of power modules 32 is increased in order to obtain a larger output, and the power conversion device 10 is installed in a place where vibration is larger from the viewpoint of securing space in the engine room (for example, on the transaxle) Even if it exists, it becomes possible to suppress the vibration of the lamination | stacking unit 30, and to suppress generation | occurrence | production of the thermal distortion in components, such as the control board 50. FIG.

  DESCRIPTION OF SYMBOLS 10 Power converter, 20 Case, 22 Attachment part, 24 Attachment surface, 26 Support part, 30 Stacking unit, 32 Power module, 34 Refrigerant flow path, 36 Signal line, 40 unit, 50 Control board, 60 Fixing member, 62 Opening Part, 64 1st fixing | fixed part, 66 2nd fixing | fixed part, 70 Screw member.

Claims (1)

A laminated unit in which a plurality of power modules including a switching element for power conversion, and a plurality of refrigerant flow paths through which a refrigerant for cooling the power module flows are laminated;
A case for housing the laminated unit;
A resin-made fixing member fixed to the outer surface of the case;
A control board fixed to the fixing member and attached to the case via the fixing member, and connected to the plurality of power modules;
A first fixing portion for fixing the control board to the fixing member;
A second fixing part for fixing the fixing member to the case;
The linear expansion coefficient of the fixing member is a value closer to the linear expansion coefficient of the control board than the linear expansion coefficient of the case,
The first fixing part and the second fixing part are arranged at different positions in the fixing member,
The power converter characterized by the above-mentioned.

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