JP2020089025A - Power conversion device - Google Patents

Abstract

To provide a power conversion device in which a case is less likely to be deformed.SOLUTION: A power conversion device comprises: a layered unit 10 in which a power card 14 accommodating a semiconductor element and a cooler 12 are alternately layered; and a case accommodating the layered unit. In addition, a spring 18 that is fitted between an end face, in a layering direction, of the layered unit and a support portion 6 erecting from a bottom surface of the case, and that applies a load F in the layering direction to the layering unit; and a spacer 20 fitted between the support portion and the spring. A notch is provided at a corner between a surface opposite to the spacer of the support portion and an upper surface, and a projection 22 that engages with the notch is provided in a counter surface to the support portion of the spacer. A groove 28 is provided in a boundary with a projection on the counter surface and a bottom surface side of the projection, and a gap is ensured between a part higher than a groove in the counter surface and the support portion. Thus, interference between a fillet R3 that may arise at a root of the projection and an edge corner of the notch is avoided.SELECTED DRAWING: Figure 3

Description

The technique disclosed in the present specification relates to a power conversion device. In particular, the present invention relates to a power conversion device including a laminated unit in which a power card containing a semiconductor element and a cooler are alternately laminated.

An inverter that supplies electric power to a motor or a voltage converter that converts a voltage may employ a structure in which semiconductor elements such as IGBTs that generate a large amount of heat are integrated separately from other circuits and are cooled intensively. As one of such integrated structures, there is known a laminated unit in which a flat plate type power card containing a semiconductor element having a large heat generation and a flat plate type cooler are alternately laminated.

The laminated unit is attached to the case while pressure is applied in the laminating direction so that heat can be well transferred from the power card to the cooler. Specifically, a spring is fitted and inserted between an end face in the stacking direction of the stacked unit and a support portion standing upright from the bottom surface of the case, and the spring applies pressure to the stacked unit. On the other hand, when a large number of power cards and coolers are stacked, the stacking unit has a large variation in the length in the stacking direction. The variation in the length in the stacking direction is one of the factors that make the pressing force of the stacking unit non-uniform and deteriorate the heat transfer efficiency from the power card to the cooler. In Patent Document 1, a spacer is arranged between the spring and the supporting portion in order to suppress the variation in the pressing force of the laminated unit. The spacer has a plurality of convex portions having different protruding lengths, and the convex portion of the spacer and the concave portion of the supporting portion of the case fit into each other. The respective convex portions are provided on different surfaces of the spacer. Patent Document 1 discloses a technique in which the distance between the spring and the support portion can be adjusted by changing the direction of the spacer and changing the combination of the convex portion of the spacer and the concave portion of the support portion. In patent document 1, the above-mentioned support part is called a stopper part.

JP, 2013-162541, A

In the power conversion device disclosed in Patent Document 1, the protrusion of the spacer and the recess of the support are fitted together. In order to fix the position of the spacer with respect to the case, the side surface of the convex portion of the spacer is brought into contact with the inner surface of the concave portion of the support portion. Therefore, at the root of the protrusion of the spacer, the two orthogonal surfaces of the spacer, that is, the surface facing the support and the side surface of the protrusion contact the support.

A minute fillet (a curved surface of a boundary between two planes) may be formed at the base of the convex portion of the spacer. This fillet is generated in the spacer manufacturing process. As described above, at the base of the convex portion of the spacer, two orthogonal surfaces are in contact with the supporting portion. Therefore, when a fillet occurs at the base of the convex portion of the spacer, the corner of the edge of the concave portion of the supporting portion is Fillets interfere. As described above, the spacer receives the force for pressing the laminated unit from the elastic member. Further, since the concave portion of the supporting portion is formed on the upper surface of the supporting portion, the supporting portion is easily deformed when the spring load is biased toward the concave portion. Therefore, when the fillet at the base of the convex portion of the spacer and the corner of the concave portion of the supporting portion interfere with each other, the supporting portion is deformed in a direction in which the upper side falls and moves away from the spacer.

When the upper side of the support portion is deformed in the direction away from the spacer, the force for pressing the laminated unit becomes small. This specification discloses a power conversion device that suppresses deformation of a support portion due to interference between a fillet at the base of a convex portion of a spacer and a recess of a support portion.

The power conversion device disclosed in the present specification includes a laminated unit in which a power card containing a semiconductor element and a cooler are alternately laminated, and a case containing the laminated unit. Further, this power conversion device is fitted and inserted between an end face in the stacking direction of the stacking unit and a support portion standing upright from the bottom surface of the case, and a spring for applying a load in the stacking direction to the stacking unit, A spacer is fitted between the support portion and the spring.

In this power conversion device, a notch is provided at a corner between a surface of the supporting portion facing the spacer and the upper surface, and a convex portion that fits into the notch is provided on a surface of the spacer facing the supporting portion. Further, a groove is provided at a boundary between the convex portion of the facing surface and a bottom surface side of the convex portion, and a gap is secured between the groove above the facing surface and the supporting portion.

In the power conversion device described above, the groove is provided at the boundary with the convex portion on the facing surface of the spacer and at the boundary with the bottom surface side of the convex portion. When the protrusion is fitted into the notch, the fillet on the bottom surface side of the root of the protrusion is located in the groove. Therefore, the fillet does not interfere with the corners of the notch of the support.

In the above-described power conversion device, a gap is secured between the groove above the facing surface of the spacer and the support portion. That is, the facing surface of the spacer does not contact the supporting portion above the groove. Since the fillets on the left and right sides of the root of the convex portion are located in the gap, they do not interfere with the corners of the notch of the support portion. That is, the spacer does not bias the load to the upper side of the support portion. The power conversion device disclosed in this specification can suppress the deformation of the support portion by avoiding the interference between the fillet at the base of the convex portion of the spacer and the corner of the edge of the notch of the support portion.

Details of the technology disclosed in the present specification and further improvements will be described in “Mode for Carrying Out the Invention” below.

It is a top view of the power converter of an Example. It is an enlarged view which shows the spacer periphery. FIG. 3 is a partial cross-sectional view of the power converter of the embodiment taken along the line III-III in FIG. 2. It is a perspective view of a spacer.

A power conversion device 2 according to an embodiment will be described with reference to the drawings. The power conversion device 2 of the embodiment is an inverter that is mounted on an electric vehicle and that converts the DC power of a battery into AC power for driving a motor. The power conversion device 2 includes a large number of semiconductor elements such as IGBTs and diodes (reflux diodes) that handle large currents. Unlike the circuit for digital signals, these elements pass a current of several tens to several hundreds of amperes, and therefore generate a much larger amount of heat than the circuit for digital signals. Therefore, the power conversion device 2 has a laminated unit 10 in which semiconductor elements such as IGBTs that generate a large amount of heat are separated from the digital signal circuit and integrated.

FIG. 1 is a plan view of a power conversion device 2 of the embodiment. As shown in FIG. 1, the power conversion device 2 includes a case 4, a laminated unit 10, a spring module 18, and a spacer 20. In the present specification and the drawings, the spring module 18 that pressurizes the laminated unit 10, the support portion 6 provided in the case 4, and the spacer 20 that is fitted between them will be focused and described. Therefore, description and illustration of other components such as a large-capacity capacitor, a reactor, and terminals of switching elements are omitted.

The case 4 is a housing that houses the laminated unit 10, the spring module 18, and the spacer 20. The case 4 has two support portions 6 standing on the positive side in the X-axis direction from the bottom surface. The support portion 6 is a column having a substantially square cross section. The support portion 6 has a groove 6a extending in the X-axis direction on the upper surface. The structures of the two support portions 6 of the case 4 are the same.

The laminated 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. The power card 14 is a package in which two semiconductor elements 14a and 14b (see FIG. 3) are molded with resin. In order to cool the semiconductor elements included in the power card 14, the power card 14 is sandwiched by the coolers 12 from both sides.

The cooling medium flows through the inside of the cooler 12. When viewed from the stacking direction (X-axis direction in the drawing), the cooler 12 has through holes on both sides with the power card 14 interposed therebetween, 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 on the negative side in the X-axis direction of the laminated unit 10. The coolant supply pipe 8a and the coolant discharge pipe 8b extend to the outside of the case 4 and are connected to a coolant circulation device (not shown). Refrigerant is supplied to the laminated 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.

The power card 14 and the cooler 12 conduct heat by bringing their wide surfaces into contact with each other. In order to promote this heat conduction, a load is applied to the stacking unit 10 in the stacking direction by the spring module 18. The spring module 18 includes a pressure distribution plate and a plate spring. The wide surface of the pressure distribution plate comes into contact with the wide surface of the cooler 12 at the end opposite to the cooler 12 connected to the refrigerant supply pipe 8a and applies a load in the stacking direction. The spring module 18 has two leaf springs. When the leaf spring is deformed, the spring module 18 generates a load in the stacking direction.

The amount of deformation of the leaf spring of the spring module 18 is determined by the length of the laminated unit 10 in the laminating direction and the length of the space in which the laminated unit 10 of the case 4 is inserted. Since the plurality of coolers 12 and the power card 14 are laminated in the laminated unit 10, the length easily varies. In order to absorb this variation, a spacer 20 is fitted between the leaf spring of the spring module 18 and the support portion 6 of the case 4.

The detailed structure of the spacer 20 and the support portion 6 will be described with reference to FIG. FIG. 2 is an enlarged view of the vicinity of the spacer 20 on the Y axis direction positive side in FIG. As described above, the spacer 20 is in contact with the leaf spring of the spring module 18. Therefore, the spacer 20 receives the load F from the spring module 18.

The spacer 20 has a convex portion 22, a first facing surface 24, and a second facing surface 26. The first facing surface 24 and the second facing surface 26 face the load bearing surface 6b of the support portion 6. The second facing surface 26 and the load receiving surface 6b are in contact with each other. Therefore, the load F received by the spacer 20 from the spring module 18 is transmitted to the support portion 6 via the spacer 20. On the other hand, as shown in FIG. 2, a gap S is secured between the first facing surface 24 and the load receiving surface 6b of the support portion 6. The spacer 20 has a protrusion 22 at the center of the first facing surface 24. The width of the convex portion 22 in the Y-axis direction is approximately half the width of the spacer 20 main body in the Y-axis direction. The length of the convex portion 22 in the X-axis direction is approximately one third of the length of the spacer 20 main body in the X-axis direction.

Further, the support portion 6 has a groove 6a on the upper surface. The groove 6a penetrates from the load receiving surface 6b of the support portion 6 to the opposite surface. In other words, the groove 6a is a notch provided at a corner between the load receiving surface 6b and the upper surface of the support portion 6.

The convex portion 22 of the spacer 20 has a part of both surfaces in the Y-axis direction abutted on the inner surface of the groove 6 a of the support portion 6. As will be described later, the lower surface of the convex portion 22 is also in contact with the bottom surface of the groove 6a. That is, the position of the spacer 20 with respect to the case 4 is determined by the fitting of the convex portion 22 and the groove 6a. In other words, the convex portion 22 corresponds to a positioning structure for the spacer 20 with respect to the case 4.

As shown in FIG. 2, the side surface of the convex portion 22 of the spacer 20 and the first facing surface 24 are connected by fillets R1 and R2. As described above, the gap S is secured between the first facing surface 24 and the load receiving surface 6b of the support portion 6. Therefore, the fillets R1 and R2 are accommodated in the gap S. That is, the fillets R1 and R2 do not interfere with the corners of the edges of the groove 6a of the support portion 6.

The groove 28 of the spacer 20 will be described with reference to FIG. FIG. 3 is a partial cross-sectional view of the power conversion device 2 taken along the line III-III in FIG. In FIG. 3, in order to facilitate understanding of the positional relationship between the spacer 20 and the laminated unit 10, a part of the laminated unit 10 is added to the cross-sectional view of the spacer 20 and the supporting portion 6. As shown in FIG. 3, the spacer 20 is fitted and inserted between the support portion 6 standing upright from the bottom surface of the case 4 and the leaf spring of the spring module 18. As described above, the protrusion 22 is provided on the spacer 20. The lower surface of the convex portion 22 is in contact with the bottom surface of the groove 6 a of the support portion 6. As a result, the position of the spacer 20 in the height direction with respect to the support portion 6 is fixed. The spacer 20 has a second facing surface 26 that abuts the load receiving surface 6b of the support portion 6 at the lower portion. A groove 28 is provided on the boundary between the second facing surface 26 and the convex portion 22 on the bottom surface side.

As shown in FIG. 3, a fillet R3 is attached to the root of the lower side of the convex portion 22. The fillet R3 is located inside the groove 28. In other words, the fillet R3 is housed in the groove 28. Therefore, the fillet R3 does not interfere with the corner of the edge of the groove 6a of the support portion 6. As described above, in the power conversion device 2 of the embodiment, by providing the groove 28 and the first facing surface 24 in the spacer 20, the fillets R1 to R3 attached to the root of the convex portion 22 of the spacer 20 and the groove 6a are provided. Edge corner interference can be avoided. The effect of avoiding interference between the fillets R1 to R3 and the groove 6a will be described later.

The spacer 20 has, below the second facing surface 26, an inclined surface that is inclined so as to be farther from the support portion 6 toward the lower side. In the process of assembling the power conversion device 2, when the spacer 20 is inserted from above between the laminated unit 10 and the support portion 6 of the case 4, the inclined surface serves as a guide.

Here, the positional relationship in the height direction of the load received from the spring module 18 on the groove 28 and the spacer 20 will be described with reference to FIG. Since the spring module 18 applies a load to the laminated unit 10 as described above, the spacer 20 receives a load from the leaf spring of the spring module 18 due to its reaction force. The laminated unit 10 uses the cooler 12 to cool the heat generated from the semiconductor elements 14a and 14b of the power card 14. That is, the portion of the spring module 18 that needs to be applied to the cooler 12 by applying a load in the stacking direction is the portion where the semiconductor elements 14a and 14b of the power card 14 are arranged. It is not necessary to cool the portion where the semiconductor elements 14a and 14b are not arranged by the cooler 12. That is, it is not necessary to apply a load to the portions where the semiconductor elements 14a and 14b are not arranged.

As shown in FIG. 3, in the spacer 20, the groove 28, the first facing surface 24 having a gap between it and the load receiving surface 6b, and the lower slope are located in the portions where the semiconductor elements 14a and 14b are not arranged. It is provided. In other words, the portion of the spacer 20 that does not come into contact with the support portion 6 is provided in a portion where the semiconductor elements 14a and 14b are not arranged. That is, in the portion where the semiconductor elements 14 a and 14 b are arranged, the spacer 20 is in contact with the spring module 18, and the second facing surface 26 of the spacer 20 is in contact with the load receiving surface 6 b of the support portion 6. The spacer 20 transfers the load F of the spring module 18 to the support portion 6 of the case 4 in the portion where the semiconductor elements 14a and 14b are arranged in the height direction, thereby applying the load of the spring module 18 to the cooler 12. There is. Thereby, the heat generated from the semiconductor elements 14a and 14b is efficiently transmitted to the cooler 12.

The convex portion 22 of the spacer 20 and the groove 6a of the support portion 6 are located higher than the semiconductor elements 14a and 14b. As described above, the load receiving surface 6b of the supporting portion 6 contacts the second facing surface 26 of the spacer 20 and supports the reaction force of the spring module 18. When the fillets R1 to R3 of the convex portion 22 interfere with the edges of the groove 6a, the reaction force is biasedly applied to the interference portion between the fillets R1 to R3 and the edge of the groove 6a. When a biased load is applied to the vicinity of the upper end of the support portion 6, the support portion 6 is easily deformed in the direction away from the laminated unit 10. The deformation of the support portion 6 weakens the load applied to the laminated unit 10 by the spring module 18. The power converter 2 of the embodiment has a structure in which the fillets R1 to R3 do not interfere with the edges of the groove 6a. The power conversion device 2 of the embodiment can suppress the deformation of the support portion 6.

The shape of the spacer 20 will be described with reference to FIG. FIG. 4 is an upper perspective view showing the shape of the spacer 20. The spacer 20 has a columnar shape with a rectangular cross section having a rectangular cross section extending in the height direction, and has a convex portion 22 and a first facing surface 24 on the upper portion. The lower end is a slope, and has a second facing surface 26 above the slope. The first facing surface 24 and the second facing surface 26 are separated by a groove 28. The spacer 20 is made of metal such as iron, and is manufactured by, for example, casting. Therefore, fillets are generated at the corners of the spacer 20 due to requirements such as ease of removal from the casting mold. Fillets R1 to R3 are generated at the base of the convex portion 22, and the lower fillet R3 is generated inside the groove 28. The spacer 20 may be manufactured by cutting out metal.

The points to be noted in the present embodiment will be described below. The groove 6a provided on the upper surface of the support portion 6 penetrates from the load receiving surface 6b to the surface on the opposite side. The groove 6a does not have to penetrate to the surface opposite to the load receiving surface 6b. That is, the groove 6a (notch) may be provided at a corner between the load receiving surface 6b and the upper surface of the support portion 6.

In the spacer 20 of the power converter 2 of the embodiment, the groove 28 is provided deeper than the first facing surface 24, but the technique disclosed in this specification is not limited to this. The groove and the first facing surface may have the same depth. Also, the number and shape of the spacers differ depending on the shape and structure of the spring module. The position and shape of the support portion and the shape of the notch also vary depending on the shape and structure of the spring module.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in the present specification or the drawings exert technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technique illustrated in the present specification or the drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes has technical utility.

2: Power conversion device 4: Case 6: Support part 6a: Groove 6b: Load receiving surface 8a: Refrigerant supply pipe 8b: Refrigerant discharge pipe 10: Laminated unit 12: Cooler 14: Power cards 14a, 14b: Semiconductor element 16: Connection pipe 18: Spring module 20: Spacer 22: Convex portion 24: First facing surface 26: Second facing surface 28: Grooves R1 to R3: Fillet S: Gap F: Load

Claims (1)

A laminated unit in which a power card containing a semiconductor element and a cooler are alternately laminated,
A case accommodating the laminated unit,
A spring, which is inserted between an end face in the stacking direction of the stacking unit and a support portion standing from the bottom surface of the case, and which applies a load in the stacking direction to the stacking unit,
A spacer fitted between the support portion and the spring;
Is equipped with
A notch is provided at a corner between a surface of the supporting portion facing the spacer and an upper surface,
On a surface of the spacer facing the support portion, a convex portion that fits into the notch is provided,
A groove is provided at a boundary between the facing surface and the convex portion and a boundary between the convex portion and the bottom surface side, and a gap is secured between the groove on the facing surface and the supporting portion. The power conversion device.

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