JP5169764B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device using a plurality of heat generating elements having different heat generation amounts.

  In a hybrid vehicle having two power sources with different operating principles, a motor that is one of the power sources is used to improve the fuel consumption rate and the emission performance. A power converter for converting the power of the DC power source into three-phase AC power for driving the motor is mounted. In this type of power conversion device, switching elements such as IGBT (Insulated Gate Bipolar Transistor) and MOS (Metal Oxide Semiconductor), which are semiconductor elements for power conversion, and rectifier elements such as diodes are generally used.

  In the above-described power conversion device, each semiconductor element to be mounted generates heat due to switching loss or steady loss. Therefore, in order to maintain a predetermined operation guarantee temperature for such a semiconductor element, each semiconductor element that is a heating element A cooler is used for cooling. As for the cooling mode in such a cooler, various proposals have been conventionally made, such as a proposal for improving the cooling efficiency of each semiconductor element and a proposal for suppressing the power loss.

  For example, in Patent Document 1, the heat conductivity between the semiconductor element and the cooler is focused on, and the heat sink with the cooling fin and the semiconductor element are joined by the high heat conductive grease or the high heat conductive adhesive. With such a configuration, the cooling efficiency related to each semiconductor element is improved. Further, when a silicon substrate and a silicon carbide substrate are used as a base material of a semiconductor element, for example, as shown in Patent Document 2, a semiconductor stack structure in which a semiconductor element and a cooler are stacked is connected in series. Also known is a technology for improving the cooling efficiency of each semiconductor element by arranging a silicon semiconductor with a large calorific value upstream of the cooler and a silicon carbide semiconductor with a small calorific value downstream. .

Further, in Patent Document 3, based on the viewpoint that the temperature at which the steady loss of the switching element is reduced and the temperature at which the steady loss of the rectifying element is reduced, the switching element and the rectifying element mounted on the mounting surface of one substrate In contrast, a coolant passage that provides a different cooling state is formed, and an optimum operating temperature is realized by changing the cooling capacity of each semiconductor element.
JP 2007-36214 A JP 2006-303306 A JP 2006-210605 A

  By the way, in Patent Document 1, a lead frame of a DBC (Direct Bonding Copper) substrate on which each semiconductor element is mounted and a bus bar built-in substrate, which is a substrate with a built-in bus bar, are joined by soldering so-called wire bondless structure. Is realized. In such a wire bondless structure, it is possible to simplify the device structure of the power conversion device compared to the case of using a large amount of wire bonding, in addition to the improvement of the cooling efficiency and the suppression of power loss described above, It is possible to improve the reliability and reworkability of the power conversion device.

However, even in the power conversion device adopting the wire bondless structure, since a plurality of semiconductor elements are mounted on one mounting surface, the device size in the surface direction of the mounting surface is mounted. It is limited to the area occupied by the semiconductor element. In particular, when using a heat sink with cooling fins as shown in Patent Document 1, the proportion of the cooler occupying the entire volume of the power converter increases, and all the components mounted on the mounting surface as described above. In this aspect of cooling the semiconductor element, it is necessary to dispose such a cooler over substantially the entire side surface facing the mounting surface. Therefore, in such a power conversion device, there is a problem that it is difficult to reduce the size of the cooler and thus the power conversion device itself because the size of the mounting surface is restricted.

  This invention is made | formed in view of the said actual condition, The objective is to provide the power converter device which enabled size reduction of an apparatus size.

In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, the first mounting substrate having the first mounting surface on which the first heat generating element is mounted and the second heat generating element having a heat generation amount higher than that of the first heat generating element are mounted. A second mounting substrate having two mounting surfaces and having a cooling body bonded to a surface to be cooled, which is a side surface facing the second mounting surface, and the first heating element and the second heating element are bonded. A power conversion device including a bus bar, wherein the first mounting surface and the second mounting surface intersect with each other in such a manner that the first heat generating element and the second heat generating element face inward. A substrate and the second mounting substrate are joined, and the bus bar has a first connection surface that is a side surface facing the first mounting surface and a second connection surface that is a side surface facing the second mounting surface. The first heating element is joined to the first connection surface, and the second generation surface is joined to the second connection surface. Element is summarized in that the first heating element is bonded is mounted.

  According to such a configuration, the first heat generating element and the second heat generating element are separately mounted on the first mounting surface and the second mounting surface that intersect with each other. Each is directly connected to a different side of the bus bar. Therefore, not only the wire bondless structure can be easily realized, but also when mounting a plurality of heating elements, the surface of the bus bar can be used three-dimensionally. Compared with the mode of mounting on a surface, the device size in the surface direction of the mounting surface can be reduced. In addition, since such a bus bar plays a part of the protection function for protecting the heat generating elements, the number of parts can be reduced, and in addition to further miniaturization of the power conversion device, the device structure can be simplified.

  In addition, for example, a semiconductor element made of silicon carbide generally has a small heat generation amount corresponding to power loss, and has a higher operation guarantee temperature than a semiconductor element made of silicon, so that the use temperature is high. Reliable operation can be obtained. According to the above-described configuration, for example, by using such a semiconductor element made of silicon carbide as the second heat generating element, a reliable operation can be obtained without disposing a cooling body on the first mounting substrate, and relatively heat generation can be achieved. Since the cooling body is disposed only on the second mounting substrate whose amount is increased, the cooling body can be reduced in size, and the power converter itself can be reduced in size.

The gist of the invention described in claim 2 is that an end of the first mounting substrate on the cooled surface side is joined to the cooling body.
According to such a configuration, since the end portion of the first mounting board is directly cooled by the cooling body, even the first heating element mounted on the first mounting board can be cooled by the cooling body. That is, in the case where the first heat generating element whose calorific value is lower than that of the second heat generating element needs to be cooled according to its operating state, the place where the cooling action of the cooling body is received is the first mounting board. Although it is an edge part, the cooling can be realized by such a configuration.

  According to a third aspect of the present invention, the first mounting substrate and the second mounting substrate are bonded in such a manner that an end surface of the first mounting substrate on the second mounting substrate side is flush with the surface to be cooled. The gist is that the end surface of the first mounting substrate and the surface to be cooled are joined to the main surface of the cooling body.

  According to such a configuration, heat exchange is performed between the end surface of the first mounting substrate and the main surface of the cooling body to cool the first mounting substrate, so that the first size can be reduced while reducing the size of the device. It is also possible to reduce the temperature of the heating element.

  According to a fourth aspect of the present invention, the first mounting substrate and the second mounting substrate are joined in such a manner that the cooled surface intersects in the middle of the first mounting surface, and the main surface of the cooling body Is bonded to the cooled surface, and the end surface of the cooling body is bonded to the first mounting surface.

  According to such a configuration, heat exchange is also performed between the first mounting surface and the end surface of the cooling body to cool the first mounting substrate, so that the size of the first heating element can be reduced while reducing the size of the device. The temperature can be lowered.

The gist of the invention described in claim 5 is that an angle formed by the first mounting surface and the second mounting surface is a right angle.
According to such a configuration, since the cross-sectional shape of the bus bar connected to the first heat generating element and the second heat generating element can be configured by a simple shape such as a rectangle, the structure of the bus bar can be further simplified. In addition, in the connection part between each heating element and the bus bar, the angle formed by the joint surface of the bus bar is the same as the angle formed by the mounting surface. Therefore, in the process of connecting the bus bar and each heating element, The connection work can be further facilitated, and the connection state can be further stabilized and the positional alignment between the joint surface and the mounting surface can be improved.

The gist of the invention described in claim 6 is that an angle formed by the first mounting surface and the second mounting surface is an obtuse angle.
According to such a configuration, since the side of the second mounting surface viewed from the second mounting substrate is greatly opened, the second heating element and the second heating element are mounted on the second mounting surface and the first mounting surface, In the process of connecting the bus bars, the connection work can be further facilitated, the connection state can be further stabilized, and the positional alignment between the joint surface and the mounting surface can be improved.

  According to a seventh aspect of the present invention, a pair of the first mounting boards are joined to the second mounting board in such a manner as to sandwich one second mounting board, and the positive bus and the negative bus that are the pair of bus bars. Are mounted on one side of the first mounting surface and the other side of the first mounting surface on the second mounting surface, respectively, and the second heating element is disposed between the positive electrode bus and the negative electrode bus. A pair of the switching element and the rectifying element that is the first heating element connected in reverse parallel to the switching element are connected in a three-phase bridge, and the first mounting surface and the second The mounting surface is connected to the rectifying element and the switching element connected to the positive electrode bus, respectively, and the first mounting surface and the second mounting surface in the vicinity of the negative electrode bus are connected to the negative electrode bus, respectively. Said said Flow element and the switching element and summarized in that is connected.

According to such a configuration, a pair of a switching element connected to the positive electrode bus and a rectifying element connected in reverse parallel to the switching element is mounted on the positive electrode bus side in the mounting space and connected to the negative electrode bus And a pair of rectifying elements connected in antiparallel to the switching elements are mounted on the negative electrode bus side in the mounting space. Therefore, since the mounting positions of multiple switching elements and rectifying elements are mounted in the vicinity of the bus bar to which they are connected, the shape of the bus bar can be greatly simplified. It is also possible to reduce the size. As a result, the device structure of the power conversion device can be simplified, and the device size can be reduced. Furthermore, as the structure of the bus bar is simplified, in the process of connecting the bus bar and each heating element, the connection work can be facilitated and the connection state can be stabilized. .

(First embodiment)
Hereinafter, a first embodiment in which a power conversion device according to the present invention is embodied will be described with reference to FIGS. FIG. 1 shows an example of a circuit configuration diagram of a power converter according to the present invention.

  As shown in FIG. 1, smoothing is performed to smooth the DC voltage applied by the DC power supply 11 between the positive bus bar 12 </ b> P that is the positive bus of the DC power supply 11 and the negative bus bar 12 </ b> N that is the negative bus of the DC power supply 11 in the power converter. A capacitor 13 and an inverter circuit 14 are connected. The inverter circuit 14 is formed by three-phase bridge connection of three switching elements 15U, 15V, 15W constituting the upper arm and three switching elements 16U, 16V, 16W constituting the lower arm.

  Between the emitter electrode and the collector electrode of each switching element 15U, 15V, 15W, 16U, 16V, 16W, free-wheeling diodes 17U, 17V, 17W, 18U, 18V, 18W, which are rectifier elements, are connected in antiparallel. ing. Each of the switching elements 15U, 15V, 15W, 16U, 16V, and 16W is an IGBT (Insulated Gate Bipolar Transistor) using a silicon (Si) substrate that generates a higher amount of heat than the free-wheeling diodes 17U, 17V, 17W, 18U, 18V, and 18W. ). The free-wheeling diodes 17U, 17V, 17W, 18U, 18V, and 18W are rectifier elements that use a silicon carbide (SiC) substrate that generates less heat than the switching elements 15U, 15V, 15W, 16U, 16V, and 16W.

  These switching elements 15U, 16U and free-wheeling diodes 17U, 18U constitute a U-phase arm 20U. The U-phase output electrode 22U, which is a connection portion of the emitter electrode of the switching element 15U, the collector electrode of the switching element 16U, the positive electrode of the freewheeling diode 17U, and the negative electrode of the freewheeling diode 18U, has three phases. It is connected to the U-phase coil of the motor M.

  The switching elements 15V and 16V and the freewheeling diodes 17V and 18V constitute a V-phase arm 20V. The V-phase output electrode 22V, which is a connection part of the emitter electrode of the switching element 15V, the collector electrode of the switching element 16V, the positive electrode of the freewheeling diode 17V, and the negative electrode of the freewheeling diode 18V, is three-phase through the output line 21V of the V-phase arm. It is connected to the V-phase coil of the motor M.

  The switching elements 15W and 16W and the freewheeling diodes 17W and 18W constitute a W-phase arm. The W-phase output electrode 22W, which is a connection portion of the emitter electrode of the switching element 15W, the collector electrode of the switching element 16W, the positive electrode of the freewheeling diode 17W, and the negative electrode of the freewheeling diode 18W, is three-phase through the output line 21W of the W-phase arm. It is connected to the W phase coil of the motor M.

In the inverter circuit 14 having such a configuration, a drive signal from a gate drive circuit (not shown) that is a control device is output to each of the gate electrodes that are control poles of the six switching elements 15U, 15V, 15W, 16U, 16V, and 16W. Is done. Thereby, the DC voltage from the DC power source 11 is converted into a three-phase AC voltage and output to the three-phase motor M, and the three-phase motor M is driven.

  Next, an example of the structure of the power converter will be described with reference to FIGS. 2 is an exploded perspective view schematically showing a part of the structure of the power conversion device, and FIG. 3A is a schematic plan view showing a part of the structure of the power conversion device. ) Is a schematic side view showing the structure viewed from the side of the power converter.

  As shown in FIG. 2, the power conversion device includes a bottom plate 30 that is a second mounting board having a square plate shape, and a second mounting having a square planar shape is provided on the surface of the bottom plate 30. A bottom plate mounting surface 30a, which is a surface, is formed. In the present embodiment, one side of the bottom plate mounting surface 30a extends in the left-right direction in FIG. 2 as an output electrode direction, and a direction orthogonal to the output electrode direction on the bottom plate mounting surface 30a is referred to as a bus bar direction.

  A pair of a left side plate 31 and a right side plate 32, which are first mounting substrates, are joined to both sides of the bottom plate 30 in the output electrode direction so as to sandwich the bottom plate 30, and the bottom plate 30, the left side plate 31, and the right side plate 32 are joined. Thus, a base 33 having a substantially U-shaped cross section is formed. In the base 33, a mounting space S for mounting the upper arm and the lower arm is formed by the upper side of the bottom plate 30 being surrounded by the left side plate 31 and the right side plate 32.

  A first mounting surface (left plate mounting surface 31a) which is a right side surface of the left plate 31 is joined to the left side of the bottom plate mounting surface 30a of the bottom plate 30 so as to intersect the bottom plate mounting surface 30a. The bottom plate 30 and the left side plate 31 are joined so that an angle formed between the left side plate mounting surface 31a and 30a is a right angle. A first mounting surface (right plate mounting surface 32a), which is the left side surface of the right plate 32, is joined to the right side of the bottom plate mounting surface 30a of the bottom plate 30 so as to intersect the bottom plate mounting surface 30a. The bottom plate 30 and the right side plate 32 are joined so that the angle formed by the surface 30a and the right side plate mounting surface 32a is a right angle. An inward surface of the base 33 is formed by the bottom plate mounting surface 30a, the left side plate mounting surface 31a, and the right side plate mounting surface 32a constituting the mounting space.

The constituent material of the bottom plate 30, the left side plate 31, and the right side plate 32 may be an insulating material having high thermal conductivity. For example, silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), silicon aluminum alloy ( Mention may be made of ceramic materials such as Si ₂ Al ₃ ). The joining between the bottom plate 30 and the left side plate 31 and the joining between the bottom plate 30 and the right side plate 32 are, for example, a joining point between the bottom plate 30 and the left side plate 31 and a joining point between the bottom plate 30 and the right side plate 32. It can be realized by applying a bonding agent having high thermal conductivity to the whole.

  A bottom plate cooled surface 30b is formed on a side surface of the bottom plate 30 that faces the bottom plate mounting surface 30a, and a left side cooled surface that is a bottom side end surface of the left side plate 31 is formed on the left side of the bottom plate cooled surface 30b. The end surface 31b is formed so as to be flush with the bottom plate cooled surface 30b. Further, on the right side of the bottom plate cooled surface 30b, a right cooled end surface 32b, which is a bottom side end surface of the right plate 32, is formed so as to be flush with the bottom plate cooled surface 30b. The bottom plate cooled surface 30b, the left cooled end surface 31b, and the right cooled end surface 32b are formed with a single cooled surface 33b.

A cooler 34, which is a rectangular parallelepiped cooling body having a thickness of several centimeters in the vertical direction, is disposed on the surface to be cooled 33b, which is one flat surface. In the cooler 34, the cooling surface 34a, which is the main surface facing the surface to be cooled 33b, is formed with an external shape that matches the surface to be cooled 33b, and is joined over the entire surface to be cooled 33b. The cooler 34 is made of aluminum-based metal or the like, which is a material having high thermal conductivity, and eight refrigerant flow paths 34r for circulating cooling water as a cooling medium are formed in the inside thereof along the bus bar direction. ing. In addition, the joining between the bottom plate 30 and the cooler 34 is performed by, for example, applying a bonding agent having high thermal conductivity to the entire surface to be cooled 33 b or the entire cooling surface 34 a and screwing the cooler 34 to the base 33. It can be realized by stopping.

  In such a configuration, the cooling water is supplied from the back side to the front side in FIG. 2 with respect to each refrigerant flow path 34r, whereby the bottom plate mounting surface 30a is cooled via the bottom plate cooled surface 30b. The left plate mounting surface 31a is cooled via the left cooled end surface 31b, and the right plate mounting surface 32a is cooled via the right cooled end surface 32b. In the bottom plate cooled surface 30b in which the joining area with the cooling surface 34a is relatively large, a relatively high amount of heat can be exchanged with the cooler 34, and the joining area with the cooling surface 34a is relatively A relatively low amount of heat can be exchanged with the cooler 34 on the left cooled end face 31b and the right cooled end face 32b which become smaller. That is, the bottom plate mounting surface 30a, the left side plate mounting surface 31a, and the right side plate mounting surface 32a are all cooled by the single cooler 34 under different cooling efficiencies. Moreover, the bottom plate cooled surface 30b that obtains a relatively high cooling efficiency occupies a large area with respect to the cooling surface 34a, and the left cooled end surface 31b and the right cooled end surface 32b that have a relatively low cooling efficiency are the cooling surfaces 34a. Therefore, the entire cooling surface 34a can be used effectively.

  On the bottom plate mounting surface 30a, the U-phase output electrode 22U, the V-phase output electrode 22V, and the W-phase output electrode 22W, which form a strip over the entire width in the output electrode direction of the bottom plate mounting surface 30a, have a predetermined interval in the bus bar direction. Are arranged. The U-phase output electrode 22U, the V-phase output electrode 22V, and the W-phase output electrode 22W extend upward from both ends in the output electrode direction on the bottom plate mounting surface 30a, respectively, on the left plate mounting surface 31a and the right side. The plate mounting surface 32a is formed over substantially the entire width in the vertical direction. The U-phase output electrode 22U, the V-phase output electrode 22V, and the W-phase output electrode 22W are continuous at right angles at the junction between the bottom plate 30 and the left side plate 31 and at the junction between the bottom plate 30 and the right side plate 32, respectively. The U-phase arm 20U, the V-phase arm 20V, and the W-phase arm 20W are mounted on these three inward surfaces, respectively.

  Note that the U-phase output electrode 22U, the V-phase output electrode 22V, and the W-phase output electrode 22W having such a U-shaped cross section are each of the U-phase output electrode 22U, the V-phase output electrode 22V, and the W-phase output electrode 22W. The bottom plate 30, the left side plate 31, and the right side plate 32 in which the regions are formed are joined as described above. Then, the corner portion where the bottom plate mounting surface 30a and the left side plate mounting surface 31a intersect and the corner portion where the bottom plate mounting surface 30a and the right side plate mounting surface 32a intersect can be realized by soldering.

  Further, on the right side plate mounting surface 32a side on the bottom plate mounting surface 30a, the U phase arm 20U and V phase arm are electrically insulated from the U phase output electrode 22U, V phase output electrode 22V, and W phase output electrode 22W. A U-phase gate extraction electrode 34U, a V-phase gate extraction electrode 34V, and a W-phase gate extraction electrode 34W associated with 20V and the W-phase arm 20W are formed, respectively.

  Next, the arrangement of each component in each phase arm and its connection mode will be described below. In addition, since the arrangement | positioning of each component in the V-phase arm 20V and the W-phase arm 20W and its connection aspect are the same as that of the U-phase arm 20U, it is about the arrangement | positioning of each component in the U-phase arm 20U, and its connection aspect below. Explanation will be given, and the description regarding the arrangement of each component in the V-phase arm 20V and the W-phase arm 20W and the connection mode thereof will be given the same reference numerals and will be omitted.

As shown in FIGS. 2 and 3, on the bottom plate mounting surface 30a, on the left plate mounting surface 31a side of the U-phase output electrode 22U, the switching element is arranged so that the gate electrode G and the emitter electrode E face upward. A collector electrode C that is the entire lower surface of 16U is joined. The gate electrode G of the switching element 16U is joined to a left gate terminal 35 extending upward from the gate electrode G, and is joined to a corresponding output terminal of the gate drive circuit via the left gate terminal 35. .

  The emitter electrode E of the switching element 15U is joined to the right side plate mounting surface 32a side of the U-phase output electrode 22U on the bottom plate mounting surface 30a so that the collector electrode C faces upward. The gate electrode G of the switching element 15U is joined to 34U. The gate electrode G of the switching element 15U is joined to the right gate terminal 36 via the U-phase gate lead electrode 34U, and is joined to the corresponding output terminal of the gate drive circuit via the right gate terminal 36. Yes.

  An output line 21U of a U-phase arm extending in the busbar direction is joined to the U-phase output electrode 22U on the bottom plate mounting surface 30a at substantially the center of the U-phase output electrode 22U. . The output line 21U is insulated from the V-phase output electrode 22V, the W-phase output electrode 22W, and the output lines 21V and 21W.

  The cathode K of the reflux diode 18U is joined to the U-phase output electrode 22U on the left plate mounting surface 31a so that the anode A faces inward, and the U-phase output electrode 22U on the right plate mounting surface 32a. The anode A of the reflux diode 17U is joined in such a manner that the cathode K faces inward.

  The bonding between the bottom plate mounting surface 30a and each electrode, the bonding between the left plate mounting surface 31a and the freewheeling diode 18U, and the bonding between the right plate mounting surface 32a and the freewheeling diode 17U are performed by solder, aluminum, Alternatively, it is realized by once melting copper or the like at the time of mounting each element.

  On the left plate mounting surface 31a side on the bottom plate mounting surface 30a, a negative electrode bus bar 12N made of a rectangular columnar copper material extending in the bus bar direction is shared by the U-phase arm 20U, the V-phase arm 20V, and the W-phase arm 20W. It extends over the entire width of the base 33 in the bus bar direction. The emitter electrode E of the switching element 16U is joined to the bottom side connection surface 12Na (second connection surface) which is the side surface facing the bottom plate mounting surface 30a in the negative electrode bus bar 12N, and the left side plate mounting in the negative electrode bus bar 12N. The anode A of the reflux diode 18U is joined to the left connection surface 12Nb (first connection surface) which is the side surface facing the surface 31a. In this negative electrode bus bar 12N, in a region facing the gate electrode G of the switching element 16U, a notch 12Nc opened to the right side of the negative electrode bus bar 12N is formed over the entire width in the vertical direction. By disposing the left gate terminal 35 in the notch 12Nc, the negative bus bar 12N and the left gate terminal 35 are separated from each other, and the negative bus bar 12N and the gate electrode G of the switching element 16U are electrically insulated. It has become so.

On the side of the right side plate mounting surface 32a on the bottom plate mounting surface 30a, the positive electrode bus bar 12P made of a rectangular columnar copper material extending in the bus bar direction is provided with the U-phase arm 20U, the V-phase arm 20V, and the W-phase arm. It extends over the entire width of the base 33 in the bus bar direction in a form common to 20 W. The collector electrode C of the switching element 15U is joined to the bottom side connection surface 12Pa (second connection surface) which is the side surface facing the bottom plate mounting surface 30a in the positive electrode bus bar 12P, and the right side plate mounting in the positive electrode bus bar 12P. The cathode K of the reflux diode 17U is joined to the right connection surface 12Pb (first connection surface) that is the side surface facing the surface 32a. In the positive bus bar 12P, a notch 12Pc that opens to the left side of the positive bus bar 12P is formed in a region facing the U-phase gate lead electrode 34U. By disposing the right gate terminal 36 in the notch 12Pc,
The positive bus bar 12P and the right gate terminal 36 are separated from each other so that the positive bus bar 12P and the gate electrode G of the switching element 15U are electrically insulated.

  The mounting of the negative electrode bus bar 12N described above is performed on the electrode surface of each element mounted on the base 33, and bonding of solder or the like applied to the electrode surface or the bottom side connection surface 12Na and the left side connection surface 12Nb of the negative electrode bus bar 12N. It is realized by melting the material once when the negative electrode bus bar 12N is mounted, or by a method using pressure bonding or ultrasonic waves. The positive bus bar 12P is mounted on the electrode surface of each element mounted on the base body 33 in the same manner as the negative electrode bus bar 12N. The electrode surface or the bottom connection surface 12Pa and the right connection surface of the positive electrode bus bar 12P. This is realized by once melting a bonding material such as solder applied to 12Pb when the positive bus bar 12P is mounted, or by a method using pressure bonding or ultrasonic waves.

According to the power converter of the first embodiment, the following effects can be obtained.
(1) In the power conversion device of the first embodiment, a so-called wire bondless structure in which each of the switching elements and each of the return diodes is directly connected to the bus bar has a bottom-side connection surface 12Na in the negative electrode bus bar 12N and This can be realized by using the left connection surface 12Nb, the bottom connection surface 12Pa and the right connection surface 12Pb in the positive bus bar 12P. Therefore, when mounting each of the switching elements and the reflux diode, not only a wire bondless structure can be realized, but also mounting using the surfaces of the positive bus bar 12P and the negative bus bar 12N in three dimensions becomes possible. Therefore, the device size in the surface direction of the mounting surface can be reduced as compared with a mode in which the switching elements and the return diodes are mounted on a common mounting surface.

  (2) According to the power conversion device of the first embodiment, the positive bus bar 12P and the negative bus bar 12N cover the junction surfaces of the switching elements and the free wheel diodes, so that the positive bus bar 12P and the negative bus bar 12N It also functions as a protective material for protecting each semiconductor element. Therefore, the structure and the size of the power conversion device can be simplified as compared with the case where a separate protective material is provided. Furthermore, the reworkability in the manufacturing process of the power conversion device can be improved as compared with the case where a separate protective material is provided.

  (3) According to the power conversion device of the first embodiment, the angle formed between the bottom plate mounting surface 30a and the left side plate mounting surface 31a and the angle formed between the bottom plate mounting surface 30a and the right side plate mounting surface 32a are right angles. Therefore, the cross-sectional shape of the positive electrode bus bar 12P and the negative electrode bus bar 12N can be a simple rectangular shape. Therefore, it is possible to improve the position matching of the positive bus bar 12P and the negative bus bar 12N with respect to each switching element and freewheeling diode.

  (4) In the power conversion device of the first embodiment, although the amount of heat generated by each switching element is higher than the amount of heat generated by each freewheeling diode during operation, the switching element is cooled. Since the substantially entire surface of the bottom plate cooled surface 30b is joined to the cooling surface 34a of the cooler 34, each switching element can be effectively cooled. In addition, since the heat generation amount of each freewheeling diode is lower than the heat generation amount of each switching element, it is possible to maintain the guaranteed operation range by radiating heat to the outside air. Even if this is not possible, the operation guarantee range can be maintained by the cooling effect via the left cooled end surface 31b and the right cooled end surface 32b. Therefore, it is not necessary to separately provide a cooler for cooling the free-wheeling diode on the left side plate 31 and the right side plate 32, so that the power converter can be simplified and reduced in size.

(5) According to the power conversion device of the first embodiment, since the cooler 34 is a water-cooled type, the cooling efficiency of each switching element and each return diode can be increased as compared with an air-cooled type cooler.
(Second Embodiment)
A second embodiment that embodies the power converter according to the present invention will be described below with reference to FIG. In addition, in 2nd Embodiment, since the structure of the baseplate 30, the left side board 31, and the right side board 32 in 1st Embodiment was changed, the changed part is demonstrated in detail below.

  As shown in FIG. 4, the bottom plate 30, the left side plate 31, and the right side plate 32 are thin insulating substrates having a thickness of several millimeters, and are formed sufficiently thinner than the vertical thickness of the cooler 34. Yes. The bottom plate 30 and the left side plate 31 are joined in such a manner that the bottom plate cooled surface 30b intersects in the middle of the left side plate mounting surface 31a in the vertical direction, so that the lower end portion of the left side plate mounting surface 31a is the bottom plate covered surface. It arrange | positions so that it may extend to the cooler 34 side rather than the cooling surface 30b. Similarly to the left side plate 31, the bottom plate 30 and the right side plate 32 are joined in such a manner that the bottom plate cooled surface 30b intersects in the middle of the right side plate mounting surface 32a in the vertical direction, whereby the right side plate mounting surface 32a. It arrange | positions so that the lower side edge part may extend to the cooler 34 side.

  The thickness of the cooler 34 in the vertical direction is, for example, several centimeters and is sufficiently thicker than the thickness of the bottom plate 30, and the outer diameter of the cooling surface 34 a is a size that matches the bottom plate cooled surface 30 b. It is formed with. On both end surfaces 34b of the cooler 34 in the output electrode direction, a lower end portion of the left plate mounting surface 31a and a lower end portion of the right plate mounting surface 32a, which are located below the bottom plate cooled surface 30b, respectively. Are joined.

  For such joining between the left side plate 31 and the cooler 34, and joining between the right side plate 32 and the cooler 34, for example, a bonding agent having high thermal conductivity is applied to the whole of both end faces 34b, and each reflux is performed. This can be realized by screwing the left side plate 31 and the right side plate 32 on which the diode is mounted to the cooler 34.

According to the power converter of the second embodiment, the following effects can be obtained in addition to the power converter of the first embodiment.
(6) In the power conversion device of the second embodiment, the contact area between the cooler 34 and the left side plate 31 and the contact area between the cooler 34 and the right side plate 32 correspond to the thickness of the cooler 34. Therefore, it is possible to improve the cooling efficiency between the freewheeling diodes mounted on the left side plate mounting surface 31a and the freewheeling diodes mounted on the right side plate mounting surface 32a. That is, since the surface of the cooler 34 can be used three-dimensionally, the cooling capacity of the cooler 34 can be used effectively.

  (7) In the power conversion device of the second embodiment, the left side plate 31 is maintained in an upright state by joining one end face 34b of the cooler 34 and the left side plate 31, and The other end face 34b of the cooler 34 and the right side plate 32 are joined, whereby the standing state of the right side plate 32 is maintained. Therefore, compared with bonding using the end face of a thin substrate such as bonding between the left side plate 31 and the bottom plate 30 or bonding between the right side plate 32 and the bottom plate 30, bonding by a bonding agent or screwing is facilitated. The holding strength related to the installed state can be increased.

  (8) Since the holding strength related to the standing state can be increased as described above, the bottom plate 30, the left side plate 31, and the right side plate 32 can be reduced in thickness, and thus the power converter can be reduced in size. Can also be achieved. Furthermore, since the thermal conductivity of the bottom plate 30, the left side plate 31, and the right side plate 32 can be improved by such a thinning, the cooling efficiency of each switching element and the free wheel diode can also be improved.

The embodiment described above can also be implemented in the following manner, for example.
In the above embodiment, the bottom plate 30 and the left side plate 31, and the angle between the bottom plate mounting surface 30a and the left side plate mounting surface 31a and the angle between the bottom plate mounting surface 30a and the right side plate mounting surface 32a are perpendicular to each other. The example in which the bottom plate 30 and the right side plate 32 are joined has been described. By changing this, for example, as shown in FIG. 5 (a), the angle formed between the bottom plate mounting surface 30a and the left side plate mounting surface 31a and the angle formed between the bottom plate mounting surface 30a and the right side plate mounting surface 32a are obtuse angles. In this manner, the bottom plate 30 and the left side plate 31 and the bottom plate 30 and the right side plate 32 may be joined. At this time, the angle formed between the bottom connection surface 12Na and the left connection surface 12Nb in the negative electrode bus bar 12N and the angle formed between the bottom connection surface 12Pa and the right connection surface 12Pb in the positive electrode bus bar 12P are the same as the obtuse angle. Is preferred.

  According to such a configuration, the entire left side plate mounting surface 31a and right side plate mounting surface 32a can be visually recognized from above the bottom plate mounting surface 30a. When mounting the positive electrode bus bar 12P and the negative electrode bus bar 12N, the positive electrode bus bar 12P and The positional consistency between the negative electrode bus bar 12N and each switching element and the free wheel diode can be improved. Moreover, since the mounting work of the positive electrode bus bar 12P and the negative electrode bus bar 12N becomes easy, the joining state between each switching element or the reflux diode and the positive electrode bus bar 12P, and between each switching element or the reflux diode and the negative electrode bus bar 12N. The joining state can be made more reliable.

  Further, for example, as shown in FIG. 5B, the angle formed between the bottom plate mounting surface 30a and the left side plate mounting surface 31a and the angle formed between the bottom plate mounting surface 30a and the right side plate mounting surface 32a are acute angles. Alternatively, the bottom plate 30 and the left side plate 31 and the bottom plate 30 and the right side plate 32 may be joined. In this case as well, as in the above-described embodiment, the angle formed between the bottom connection surface 12Na and the left connection surface 12Nb in the negative electrode bus bar 12N, and the angle formed between the bottom connection surface 12Pa and the right connection surface 12Pb in the positive electrode bus bar 12P. Is preferably the same as the acute angle. Even in such a configuration, when mounting each of the switching elements and the reflux diode, not only a wire bondless structure can be realized, but also the mounting using the surfaces of the negative electrode bus bar 12N and the positive electrode bus bar 12P in three dimensions is possible. It becomes possible. Therefore, the device size in the surface direction of the mounting surface can be reduced as compared with a mode in which the switching elements and the return diodes are mounted on a common mounting surface. In addition, since the negative electrode bus bar 12N and the positive electrode bus bar 12P also function as protective materials for protecting these semiconductor elements, the structure of the power conversion device is simplified and miniaturized as compared with the case where a separate protective material is provided. Can also be planned.

  In the first embodiment, the left cooled end surface 31b that is the cooled surface of the left plate 31 and the right cooled end surface 32b that is the cooled surface of the right plate 32 are both lower end surfaces of the plates. The embodiment has been described. By changing this, for example, as shown in FIG. 6 (a), the left side plate 31 and the right side plate 32 are each configured to be bent along the bottom plate mounting surface 30a when viewed from the bus bar direction. The aspect which makes the lower surface along the baseplate mounting surface 30a the left-side cooled end surface 31b and the right-side cooled end surface 32b, which are the surfaces to be cooled, respectively. Even in such a configuration, since the size of the surface to be cooled can be increased, the cooling efficiency of the left side plate mounting surface 31a and the right side plate mounting surface 32a can be improved, and the standing state of the left side plate 31 and the right side plate 32 can be improved. It is possible to increase the holding strength related to the.

In the second embodiment, the mode in which the lower end portion of the left side plate mounting surface 31a and the lower end portion of the right side plate mounting surface 32a are joined to both end surfaces 34b in the output electrode direction of the cooler 34, respectively. . Not only this but the joining form of the left side board 31 and the cooler 34, and the joining form of the right side board 32 and the cooler 34 may be an aspect as shown, for example in FIG.6 (b). That is, a fitting recess 34c is formed in the cooling surface 34a of the cooler 34, and a fitting hole 30c is formed in the region of the bottom plate 30 facing the fitting recess 34c, and the left side plate corresponding to the fitting recess 34c. Alternatively, the left fitting convex portion 31c and the right fitting convex portion 32c formed on the lower end of 31 and the lower end of the right side plate 32 may be fitted into the corresponding fitting concave portions 34c. Even in such a configuration, since the joining range between the left side plate 31 or the right side plate 32 and the cooler 34 can be expanded, the holding strength related to the standing state of the left side plate 31 or the right side plate 32 can be increased. .

  In the above embodiment, the bonding between the bottom plate 30 and the left side plate 31 and the bonding between the bottom plate 30 and the right side plate 32 are realized by a bonding agent. For fixing the left side plate 31 and the bottom plate 30, the mode shown in FIG. 7, for example, may be used. That is, a plurality of fitting convex portions 30d are formed on the end surface of the left plate 31 in the bottom plate 30, and fitting holes 31d are formed in the region of the left plate 31 corresponding to the fitting convex portions 30d. The left side plate 31 and the bottom plate 30 may be fixed by fitting the fitting projections 30d of 30 and the fitting holes 31d of the left side plate 31. Such a joining form can also be applied to joining between the right side plate 32 and the bottom plate 30.

  In the above embodiment, the power conversion device includes one bottom plate 30 that is the first support plate, the left side plate 31 and the right side plate 32 that are the second support plates, and the positive bus bar 12P and the negative bus bar 12N that are the bus bars. The embodiment has been described. Not only in such a configuration, even if the power conversion device has one first support plate, one second support plate, and one bus bar, the surface of the bus bar is three-dimensionally as described above. Therefore, the size of the apparatus can be reduced as compared with the case where the heating elements such as the switching elements and the free-wheeling diodes are mounted on a common mounting surface.

  -In the said embodiment, as FIG. 8 shows, the structure which forms the radiation fin 50 in the side surface of the left side board 31 facing the left side board mounting surface 31a may be sufficient. With such a configuration, the contact area between the left side plate 31 and the outside air can be increased, so that the cooling efficiency related to the reflux diodes 18U, 18V, 18W can be improved. Further, such a heat radiating fin 50 can be similarly applied to the right side plate 32, whereby the cooling efficiency related to the freewheeling diodes 17U, 17V, and 17W can be improved.

  In the above embodiment, the cooler 34 is a water-cooled type. However, for cooling a heating element such as a switching element or a reflux diode, an air-cooled type cooler using a heat sink or the like may be used.

  In the above embodiment, the flow direction of the refrigerant in each refrigerant flow path 34r of the cooler 34 is set to one direction. However, for example, as shown in FIG. The flow direction may be bidirectional along the bus bar direction. According to such a configuration, when the same amount of cooling water is supplied, the flow velocity of the refrigerant in the refrigerant flow path 34r increases, and thus each switching element and each reflux diode can be efficiently cooled.

  In the above embodiment, an example in which the second heat generating element is a free-wheeling diode using a silicon carbide substrate has been described. However, the present invention is not limited to this, and the temperature at which the heat generation is small and the operation can be performed only by heat radiation to the air. If not departing from the range, the second heating element may be formed using, for example, gallium nitride.

  In the above embodiment, the first heating element is embodied as the freewheeling diodes 17U, 17V, 17W, 18U, 18V, 18W, and the second heating element is embodied as the switching elements 15U, 15V, 15W, 16U, 16V, 16W. did. The first heat generating element and the second heat generating element are not limited to such semiconductor elements, but may be elements that generate heat in accordance with the operation of the power conversion device and the amount of heat generated by the second heat generating element is higher than the amount of heat generated by the first heat generating element. Good.

In the above embodiment, the bottom plate mounting surface 30a of the bottom plate 30 and the left side plate mounting surface 31a of the left side plate 31
A plurality of heating elements are mounted on the right side plate mounting surface 32a of the right side plate 32, but the present invention is not limited to this, and is mounted on the bottom plate mounting surface 30a, the left side plate mounting surface 31a, or the right side plate mounting surface 32a. A single heating element may be provided.

The circuit diagram which showed an example of the circuit diagram of the power converter device concerning this invention. The perspective view which showed typically arrangement | positioning of each component of the power converter device in 1st Embodiment. (A) The top view which showed a part of connection state of each component of the power converter device in 1st Embodiment, (b) The side view which showed the connection state of each component of the power converter device in 1st Embodiment. . The schematic plan view after arrangement | positioning each component of the power converter device in 2nd Embodiment. (A), (b) The figure which showed typically the connection state of the baseplate in the example of a change, the left side board, and the right side board. (A), (b) The figure which showed typically the connection state of the baseplate in the example of a change, the left side board, and the right side board. The schematic perspective view which showed the connection state of the baseplate and left side board in the example of a change. The perspective view which showed a part of left side board in the example of a change. The figure which showed typically the flow of the refrigerant | coolant of the cooler in the example of a change.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... DC power supply, 12P ... Positive electrode bus bar, 12N ... Negative electrode bus bar, 13 ... Smoothing capacitor, 14 ... Inverter circuit, 15U, 15V, 15W ... Switching element, 16U, 16V, 16W ... Switching element, 17U, 17V, 17W ... Reflux Diode, 18U, 18V, 18W ... Freewheeling diode, 20U ... U phase arm, 20V ... V phase arm, 20W ... W phase arm, 30 ... Bottom plate, 30a ... Bottom plate mounting surface, 30b ... Bottom plate cooled surface, 31 ... Left side plate 31a ... left side plate mounting surface, 31d ... fitting hole, 32 ... right side plate, 32a ... right side plate mounting surface, 33 ... base, 33b ... cooled surface, 34 ... cooler, 34b ... end surface, 34r ... refrigerant flow path 50 ... radiating fins, M ... three-phase motor.

Claims (7)

A first mounting substrate having a first mounting surface on which the first heating element is mounted;
A second body having a second mounting surface on which a second heat generating element having a higher calorific value than that of the first heat generating element is mounted, and a cooling body is joined to a surface to be cooled that is a side surface facing the second mounting surface. 2 mounting boards,
A power conversion device comprising a bus bar to which the first heating element and the second heating element are joined,
The first mounting substrate and the second mounting substrate are joined such that the first mounting surface and the second mounting surface intersect with each other so that the first heating element and the second heating element face inward. And
The bus bar has a first connection surface that is a side surface facing the first mounting surface and a second connection surface that is a side surface facing the second mounting surface, and the first heat generation is formed on the first connection surface. A power conversion device, wherein an element is joined and the second heating element is joined to the second connection surface. The power converter according to claim 1, wherein an end of the first mounting board on the second mounting board side is joined to the cooling body. The first mounting board and the second mounting board are bonded in such a manner that an end surface of the first mounting board on the second mounting board side is flush with the surface to be cooled. The power converter according to claim 2, wherein an end surface and the surface to be cooled are joined to a main surface of the cooling body. The first mounting substrate and the second mounting substrate are joined in such a manner that the cooled surface intersects in the middle of the first mounting surface, and the main surface of the cooling body is bonded to the cooled surface. The power conversion device according to claim 2, wherein an end surface of the cooling body is joined to the first mounting surface. The power converter according to any one of claims 1 to 4, wherein an angle formed by the first mounting surface and the second mounting surface is a right angle. The power conversion device according to any one of claims 1 to 4, wherein an angle formed between the first mounting surface and the second mounting surface is an obtuse angle. A pair of the first mounting boards are joined to the second mounting board in such a manner as to sandwich one second mounting board, and the positive bus and the negative bus that are the pair of bus bars are respectively on the second mounting surface. Mounted on one of the first mounting surface side and the other of the first mounting surface side,
A pair of a switching element, which is the second heating element, and a rectifying element, which is the first heating element connected in reverse parallel to the switching element, is connected between the positive electrode bus and the negative electrode bus by a three-phase bridge connection. And
The rectifying element and the switching element connected to the positive electrode bus are connected to the first mounting surface and the second mounting surface in the vicinity of the positive electrode bus, respectively.
7. The rectifying element and the switching element connected to the negative electrode bus are connected to the first mounting surface and the second mounting surface in the vicinity of the negative electrode bus, respectively. Power converter.

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