JP2021129481A - Power conversion device - Google Patents

Abstract

To provide a power conversion device that suppresses the displacement of a lamination unit.SOLUTION: A power conversion device includes a lamination unit and a case. The lamination unit is formed by laminating alternately a cooler and a power card housing a semiconductor element and has a first surface existing at one end part in the lamination direction and a second surface existing at the other end part. The case includes a first support part in contact with a spring, a second support part in contact with the second surface, and a connection part connecting the first support part and the second support part. The spring is disposed between the first support part and the first surface, applies a first distribution load to the first surface in contact with the first surface, and applies a second distribution load to the second surface from the second support part. In the power conversion device disclosed herein, the resultant force of the first distribution load and the resultant force of the second distribution load act on the same axis. When only the case is observed, the first support part is inclined to get closer to the second support part as the first support part is separated from the connection part.SELECTED DRAWING: Figure 2

Description

The techniques disclosed herein relate to power converters. In particular, it relates to a power converter having a laminated unit, a spring and a case.

For example, in a power conversion device that converts DC power from a battery of an electric vehicle into AC power for driving a driving motor, semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors) that generate a large amount of heat are integrated and centrally cooled. Structures may be adopted. As one of such integrated structures, a laminated unit in which a flat plate type power card containing a semiconductor element having a large calorific value and a flat plate type cooler are alternately laminated is known.

The stacking unit may be supported by the case with a load applied in the stacking direction so that heat is well transferred from the power card to the cooler. In the power conversion device disclosed in Patent Document 1, a contact plate portion that contacts one end surface of the stacking unit in the stacking direction and a first support portion of the case (referred to as a member contact portion in Patent Document 1). A spring member is inserted between them. The spring member of Patent Document 1 is arranged in the case in a state of being urged to apply a load in the stacking direction to the stacking unit. The other end face of the laminated unit of Patent Document 1 comes into contact with the second support portion of the case (referred to as the main surface contact portion in Patent Document 1) by the urging force of the spring member.

Japanese Unexamined Patent Publication No. 2009-094257

The stacking unit of Patent Document 1 extends in the stacking direction. When the position where the urging force of the spring is applied on one end face of the laminating unit and the position where the pressing load is applied on the other end face deviate, the spring not only presses the laminating unit in the laminating direction but also exerts a moment to rotate the laminating unit. Add. Further, the laminated unit expands due to the heat generated when the power card is operated, and contracts when the power card is stopped. If the laminated unit repeatedly expands and contracts while a moment for rotating the laminated unit is applied, the position of the laminated unit shifts and the force of the spring pressing the laminated unit becomes non-uniform. As a result, the efficiency of heat conduction from the power card to the cooler may deteriorate. The present specification provides a power conversion device that suppresses misalignment of the laminated unit.

The power conversion device disclosed herein includes a stacking unit, a spring, and a case. The stacking unit is formed by alternately stacking a power card containing a semiconductor element and a cooler, and has a first surface and a other end located at one end (spring-side end) in the stacking direction. It has a second surface located at the end. The case includes a first support portion that contacts the spring, a second support portion that contacts the second surface, and a connection portion that connects the first support portion and the second support portion. The spring is arranged between the first support portion and the first surface, and abuts on the first surface to apply the first distributed load to the first surface and the second distributed load from the second support portion to the second surface. ing. In the power conversion device disclosed in the present specification, the resultant force of the first distributed load and the resultant force of the second distributed load act coaxially, and when only the case is observed (the reaction force due to the spring is not applied to the case). The first support portion is inclined toward the second support portion as it is separated from the connection portion.

The spring applies a first distributed load to the first surface and presses the second surface against the second support portion to apply a second distributed load to the second surface. Each distributed load acts on the laminated unit and the case as a resultant force. In the power conversion device described above, when only the case is observed, the first support portion is inclined toward the second support portion as it is separated from the connection portion. When the stacking unit and the spring are arranged in the case, the first support portion elastically deforms and is orthogonal to the stacking direction. As a result, the resultant force acting on the first surface and the resultant force acting on the second surface are coaxially aligned. Therefore, the spring does not apply a moment to rotate the laminated unit to the laminated unit. That is, the power conversion device disclosed in the present specification can suppress the misalignment of the laminated unit.

Details of the techniques disclosed herein and further improvements will be described in the "Modes for Carrying Out the Invention" below.

The plan view of the power conversion apparatus of an Example is shown. The cross-sectional view of the power conversion apparatus along the line II-II of FIG. 1 is shown. The range of distributed load applied to the stacking unit is shown. The manufacturing process of the power conversion apparatus of an Example is shown.

The power conversion device of the embodiment will be described with reference to the drawings. The power conversion device 2 of the embodiment shown in FIG. 1 is an inverter mounted on an electric vehicle and converting DC power of a battery into AC power for driving a traveling motor. The power conversion device 2 includes a large number of semiconductor elements that handle a large current, such as an IGBT and a diode (reflux diode). Unlike circuits for digital signals, these semiconductor elements carry a current of tens to hundreds of amperes, and therefore generate much more heat than circuits for digital signals. The power conversion device 2 has a laminated unit 10 in which semiconductor elements such as IGBTs, which generate a large amount of heat, are separated from a circuit for digital signals and integrated.

FIG. 1 is a plan view of the power conversion device 2 of the embodiment. As shown in FIG. 1, the power conversion device 2 includes a case 4, a stacking unit 10, a spring module 18, and a spacer 20. The power conversion device 2 is provided with, for example, a large-capacity capacitor, a reactor, terminals of a switching element, and the like, but description and illustration thereof will be omitted here. FIG. 1 shows a posture of looking up from the lower surface side of the case 4, and shows a state in which the removable bottom lid is removed from the case 4.

The case 4 is a housing that houses the laminated unit 10, the spring module 18, and the spacer 20. The case 4 is made of, for example, aluminum. The case 4 includes a surface 4a extending parallel to the laminating unit 10, two first support portions 6, and a second support portion 7. The first support portion 6 is erected from the surface 4a at the end portion of the stacking unit 10 on the positive side in the X-axis direction. Each first support portion 6 has a substantially square cross-sectional shape. Each of the two first support portions 6 has the same structure. As shown in FIG. 2, the power conversion device 2 is mounted on the vehicle in a posture in which the surface 4a is located above the stacking unit 10.

The second support portion 7 is arranged on the opposite side of the first support portion 6 with respect to the laminated unit 10. The second support portion 7 has a rectangular cross section. The second support portion 7 is erected from the surface 4a and is integrally formed with the inner wall on the negative side in the X-axis direction of the case 4. The first support portion 6 and the second support portion 7 are connected via a surface 4a.

The stacking unit 10 includes a plurality of power cards 14 and a plurality of coolers 12, and is a unit in which the power cards 14 and the coolers 12 are alternately laminated. A first surface 11a is provided at one end of the stacking unit 10 facing the first support portion 6. A second surface 11b is provided at the other end of the stacking unit 10 facing the second support portion 7. The power card 14 is a package in which two semiconductor elements 14a and 14b are molded with a resin. In order to cool the semiconductor element included in the power card 14, the power card 14 is sandwiched between the coolers 12 from both sides.

Refrigerant flows inside the cooler 12. When viewed from the stacking direction (X-axis direction in the drawing), the cooler 12 has through holes on both sides of the power card 14, and the connecting pipe 16 is connected to the through holes. The connecting pipe 16 connects the through holes of the adjacent coolers. A refrigerant supply pipe 8a and a refrigerant discharge pipe 8b are connected to the cooler 12 at the end on the negative side in the X-axis direction of the stacking unit 10. The refrigerant supply pipe 8a and the refrigerant discharge pipe 8b extend out of the case 4 and are connected to a refrigerant circulation device (not shown). Refrigerant is supplied to the stacking unit 10 from the outside of the power conversion device 2 via the refrigerant supply pipe 8a. The refrigerant is distributed to all the coolers 12 through each connecting pipe 16. The refrigerant absorbs heat from the adjacent power card 14 while flowing through the housing of the cooler 12. The refrigerant discharged from the cooler 12 is discharged to the outside through the other connecting pipe 16 and the refrigerant discharge pipe 8b. In FIG. 1, only the power card 14, the cooler 12, and the connecting pipe 16 arranged at the position closest to the first support portion 6 of the laminated unit 10 are designated by reference numerals.

The power card 14 and the cooler 12 conduct heat conduction by bringing their wide surfaces into contact with each other. In order to promote this heat conduction, the power conversion device 2 includes a spring module 18 that presses the stacking unit 10. The spring module 18 includes a pressure distribution plate 18a, a leaf spring fixing portion 18b, and a leaf spring 18c. The pressure distribution plate 18a has a wide surface extending along the YZ surface. The wide surface of the pressure distribution plate 18a is in contact with the first surface 11a of the laminating unit 10. Leaf springs 18c are arranged at both ends of the leaf spring fixing portions 18b fixed to the pressure distribution plate 18a. Each of the two leaf springs 18c has the same spring constant. The leaf spring 18c extends in the Y-axis direction while meandering. One end of the leaf spring 18c is fixed to the end of the leaf spring fixing portion 18b in the Y-axis direction. The other end of the leaf spring 18c is open. The leaf spring 18c is fixed to the leaf spring fixing portion 18b in the state of a cantilever whose fixing end is the end on the leaf spring fixing portion 18b side. A spacer 20 is fitted between the leaf spring 18c and the first support portion 6. The leaf spring 18c is in contact with the spacer 20. The spacer 20 is in contact with the first support portion 6.

The spacer 20 absorbs variations in length of the stacking unit 10 in the stacking direction. For example, when the length of the stacking unit 10 is shorter than the length of the stacking direction between the first support portion 6 and the second support portion 7, a spacer 20 having a large size is inserted. On the other hand, when the length of the stacking unit 10 is longer than the length in the stacking direction between the first support portion 6 and the second support portion 7, a spacer 20 having a small size is fitted. As described above, the power conversion device 2 of the embodiment stabilizes the deformation amount of the leaf spring 18c by changing the size of the spacer 20 according to the length of the stacking unit 10 in the stacking direction. As a result, the urging force of the spring module 18 applied to the laminated unit 10 is stabilized. For example, when the variation in the lengths of the laminated units 10 is small, the power conversion device 2 does not have to include the spacer 20. In that case, the leaf spring 18c comes into direct contact with the first support portion 6.

The leaf spring 18c of the spring module 18 is brought into contact with the first support portion 6 via the spacer 20 so that the tip thereof is deformed in a direction approaching the second support portion 7. When the leaf spring 18c is deformed so that the tip of the leaf spring 18c approaches the second support portion 7, the leaf spring 18c applies an elastic force to the first support portion 6 via the spacer 20. The elastic force of the leaf spring 18c causes the spring module 18 to apply an urging force to the first surface 11a of the laminated unit 10. The urging force presses the laminated unit 10 against the second support portion 7. As a result, a reaction force is applied to the second surface 11b of the laminated unit 10 from the second support portion 7. The power conversion device 2 supports the laminated unit 10 in the case 4 by the urging force of the spring module 18 applied to the first surface 11a and the reaction force applied to the second surface 11b. If the position where the urging force of the spring module 18 is applied on the first surface 11a and the position where the reaction force is applied on the second surface 11b deviate, the spring module 18 applies a moment to rotate the laminating unit 10, and the laminating unit 10 The position may shift.

In order to prevent the spring module 18 from applying a rotational moment to the laminated unit 10, the following measures are taken in this embodiment.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. In FIG. 2, in order to explain a portion where the first surface 11a is in contact with the pressure distribution plate 18a and a portion where the second surface 11b is in contact with the second support portion 7, the central portion and the case of the laminating unit 10 are described. The illustration of the end portion of 4 is omitted. As described above, the urging force of the spring module 18 is generated by the elastic force applied by the leaf spring 18c to the first support portion 6 via the spacer 20. The spring module 18 applies a force to the first support portion 6 via the spacer 20.

FIG. 4 shows a part of the manufacturing process of the power conversion device 2, and the broken line shows the case 4 only (that is, the force by the spring module 18 is not applied to the first support portion 6). The shape of the first support portion 6 is shown. The natural shape of the first support portion 6 is inclined toward the second support portion 7 as the distance from the surface 4a increases. In FIG. 4, the angle at which the first support portion 6 is tilted is shown by the angle θ. For example, the first support portion 6 has a tip of 0.2 mm with respect to its root and is inclined so as to approach the second support portion 7. When the laminated unit 10, the spring module 18, and the spacer 20 are assembled to the case 4, the spring module 18 applies a force to the first support portion 6. The first support portion 6 is elastically deformed by this force. As a result, as shown by the solid line in FIG. 4, the surface of the first support portion 6 in contact with the spacer 20 is in a posture orthogonal to the surface 4a. The first support portion 6 before elastic deformation is tilted so that the first support portion 6 is elastically deformed by the force of the spring module 18 so as to be in a posture orthogonal to the surface 4a. When the power conversion device 2 is completed, the surface of the first support portion 6 in contact with the spacer 20 faces parallel to the pressing surface of the second support portion 7. FIG. 2 shows the posture of the first support portion 6 after elastic deformation. In the completed power conversion device 2, the stacking unit 10 is arranged between two surfaces facing each other in parallel so that an orthogonal load acts on both end faces of the stacking unit 10.
The second support portion 7 is partially formed on the wall surface of the case 4, has high rigidity, and is not deformed to the extent that measures are required to prevent the second support portion 7 from being elastically deformed by the spring module 18.

Further, although FIG. 4 shows the vertical direction in accordance with the direction of FIG. 2, when the spacer 20 is actually inserted, the case 4 is turned upside down (that is, the surface 4a faces downward). ) Spacer 20 may be inserted. In the power conversion device 2 of the embodiment, when the spacer 20 is fitted between the spring module 18 and the first support portion 6, the leaf spring 18c is pushed so as to approach the pressure distribution plate 18a. As a result, a space through which the spacer 20 passes is secured between the leaf spring 18c and the inclined first support portion 6.

Further, as shown in FIG. 4, since the spacer 20 is provided with the chamfered portion 20b on the tip end side to be fitted, the spacer 20 can be easily fitted and inserted between the leaf spring 18c and the first support portion 6. .. Further, as shown in FIG. 2, the spacer 20 is fitted and inserted until the positioning portion 20a and the end face on the negative side of the Z axis of the first support portion 6 come into contact with each other. Thereby, the position of the spacer 20 in the Z-axis direction can be regulated.

The stacking unit 10 is a stack of a flat plate-shaped power card 14 and a flat plate-shaped cooler 12. When observed along the x-axis, each power card 14 is substantially rectangular and has a central axis CL, and each cooler 12 is also substantially rectangular and has a central axis CL. They are stacked so that their central axes are aligned on the same axis. The stacking unit 10 is also symmetric about the central axis CL from the viewpoint of FIG. 1 (that is, symmetric about the central axis CL from the viewpoint of FIG. 1, that is, symmetric with respect to the xz plane passing through the central axis CL. It is symmetric around the central axis CL from the viewpoint of FIG. 2 (referred to as left-right symmetry). Vertically symmetrical). The stacking unit 10 is both symmetrical and vertically symmetrical around the central axis CL.

As shown in FIG. 3C, the contact surfaces of the pair of first support portions 6 and the pair of spacers 20 are bilaterally symmetric and vertically symmetric around the central axis CL.
Similarly, the contact surfaces of the pair of spacers 20 and the pair of leaf springs 18c are also symmetrical and vertically symmetrical around the central axis CL, as shown in FIG. 3C.
Further, the spring multiplier of the leaf spring 18c is uniform regardless of the position in the spring. That is, the distribution of the spring multiplier is also bilaterally symmetric and vertically symmetric around the central axis CL.

In the following, the range in which the pressure distribution plate 18a is in contact with the first surface 11a of the laminated unit 10 is referred to as "first contact range Ta1", and the second support portion 7 of the second surface 11b is referred to. The range of contact is referred to as "second contact range Ta2".
As shown in FIG. 3B, the first contact range Ta1 is bilaterally symmetric and vertically symmetric around the central axis CL.
As shown in FIG. 3A, the second contact range Ta2 is bilaterally symmetric and vertically symmetric around the central axis CL.

When the above conditions are satisfied, that is, when the surface of the first support portion 6 in contact with the spacer 20 and the pressing surface of the second support portion 7 are parallel, and each contact surface is symmetrical and vertically symmetrical. , Various distributed loads generated from the spring module 18 are symmetrical and vertically symmetrical. That is, the following relationship can be obtained.
As shown in FIG. 2, the first distributed load Df1 applied by the pressure distribution plate 18a to the first contact range Ta1 of the stacking unit 10 is vertically symmetrical. Therefore, as shown in FIG. 2, the resultant force vector Cf1 of the first distributed load Df1 extends on the central axis CL along the central axis CL. Further, as described above, the distributed load applied by the pressure distribution plate 18a to the first contact range Ta1 is symmetrical. Therefore, even in the left-right direction, the resultant force vector Cf1 extends along the central axis CL along the central axis CL.
The resultant force here has a magnitude obtained by integrating the distributed load and has a moment equal to the moment due to the distributed load. When the distributed load is bilaterally symmetric and vertically symmetric, the moment around the central axis CL becomes zero, so that the resultant force vector extends along the central axis CL on the central axis CL.
Similarly, as shown in FIG. 2, the second distributed load Df2 applied by the second support portion 7 to the second contact range Ta2 of the stacking unit 10 is bilaterally symmetrical and vertically symmetrical. The resultant force vector Cf2 of the distributed load extends on the central axis CL along the central axis CL.
Therefore, the resultant forces acting on both end faces of the laminated unit 10 both extend on the central axis CL along the central axis CL. That is, the resultant forces acting on both end faces of the laminated unit 10 are coaxially aligned, and the relationship is such that no bending moment is applied to the laminated unit 10.

The relationship that the bending moment is not applied because the acting resultant forces are aligned on the same axis also holds for the composite of the laminated unit 10 and the spring module 18. The distributed load applied by the pair of spacers 20 to the pair of leaf springs 18c is also symmetrical and vertically symmetrical. The resultant force extends on the central axis CL along the central axis CL. The resultant force acting on both end faces of the composite of the stacking unit 10 and the spring module 18 both extends on the central axis CL along the central axis CL. That is, the resultant forces acting on both end faces of the composite are coaxially aligned, and the relationship is such that no bending moment is applied to the composite. It is prohibited that the positional relationship between the laminating unit 10 and the spring module 18 is displaced.

As shown in FIG. 3A, the range of the second contact range Ta2 in the z direction is the range of P23 to P24 shown in FIG. As shown in FIG. 3B, the range of the first contact range Ta1 in the z direction is the range of P13 to P14 shown in FIG. As shown in FIG. 3C, the range of the contact range between the leaf spring 18c and the spacer 20 in the z direction is the range of P17 to p18 shown in FIG. As shown in FIG. 3C, the range of the contact range between the spacer 20 and the first support portion 6 in the z direction is the range of P15 to p16 shown in FIG.
As shown in FIGS. 3A to 3C, the z-coordinate values of the ends P23, P13, P17, and P15 on the Z-axis positive direction side of each contact range are the same. Similarly, the z coordinate values of the ends P24, P14, P18, and P16 on the negative direction side of the Z axis of each contact range are the same. Since the range of each contact surface in the z direction (vertical direction) is uniform, it is easy to provide the resultant force of the distributed load on the same axis.

The points to be noted in the examples are described below. In the power conversion device 2 of the embodiment, the resultant force of the first distributed load Df1 and the resultant force of the second distributed load Df2 are both aligned on the central axis CL. However, the central axis CL may naturally deviate between the first surface 11a and the second surface 11b due to manufacturing variations of the power conversion device 2. The value of the variation varies depending on the size, material, structure, and the like of the parts constituting the power conversion device 2. The techniques disclosed herein tolerate this variation. Specifically, when the deviation between the central axis CL on the first surface 11a and the central axis CL on the second surface 11b is, for example, 1.0 mm or less, the positional deviation of the laminated unit 10 can be suppressed.

Further, the axis on which the resultant force of the distributed load acts is not limited to the geometric central axis of each contact range. Since the resultant force of the distributed load acts on the point where the moment generated by the distributed load becomes zero, it is sufficient that these points are arranged coaxially at both ends of the laminating unit.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above. The technical elements described herein or in the drawings exhibit their technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques illustrated in the present specification or drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

2: Power converter 4: Case 4a: Surface 6: First support 7: Second support 8a: Refrigerant supply pipe 8b: Refrigerant discharge pipe 10: Laminating unit 11a: First surface 11b: Second surface 12: Cooling Instrument 14: Power card 14a: Semiconductor element 16: Connecting tube 18: Spring module 18a: Pressure distribution plate 18b: Leaf spring fixing part 18c: Leaf spring 20: Spacer 20a: Positioning part 20b: Chamfering part CL: Central shafts Cf1, Cf2 : Differential force vector Df1: First distributed load Df2: Second distributed load

Claims (1)

Equipped with a laminated unit, spring and case,
The laminated unit is formed by alternately laminating a power card accommodating a semiconductor element and a cooler, and is located on a first surface located at one end in the laminating direction and at the other end. It has a second side that is
The case includes a first support portion that contacts the spring, a second support portion that contacts the second surface, and a connection portion that connects the first support portion and the second support portion. Ori,
The spring is arranged between the first support portion and the first surface, and abuts on the first surface to apply a first distributed load to the first surface and the second support portion on the second surface. Apply the second distributed load from
The resultant force of the first distributed load and the resultant force of the second distributed load act on the same axis.
When only the case is observed, the first support portion is a power conversion device that is inclined toward the second support portion as it is separated from the connection portion.

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