Power converter

Abstract

The objective is to provide a power conversion device that can reduce the number of connecting members between multiple semiconductor modules. [Solution] The power converter of the embodiment has a plurality of semiconductor modules stacked in the first direction. Each semiconductor module has a semiconductor chip and a conductive member disposed on at least one side of the semiconductor chip in the first direction. The conductive member has a terminal portion that can be fastened to a conductive member of another semiconductor module facing in the first direction.

Description

Technical Field

[0001] Embodiments of the present invention relate to a power conversion device.

Background Art

[0002] A power conversion device is formed by connecting a plurality of semiconductor modules. The plurality of semiconductor modules are stacked in a first direction. Each semiconductor module has a semiconductor chip. In each semiconductor module, the semiconductor chip is sandwiched in the first direction between a top plate and a heat sink (both are conductive members). The conductive members facing each other in the first direction are connected via a connecting member such as a bus bar. To form a circuit including a plurality of semiconductor modules, many additional connecting members such as bus bars were required.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a power conversion device capable of reducing the connecting members between a plurality of semiconductor modules.

Means for Solving the Problems

[0005] The power conversion device according to Aspect 1 of the embodiment has a plurality of semiconductor modules stacked in a first direction. The semiconductor module has a semiconductor chip and a conductive member disposed at least on one side of the semiconductor chip in the first direction. The conductive member has a terminal portion that can be fastened to the conductive member of another semiconductor module facing it in the first direction.

[0006] The power conversion device of Embodiment 2 is based on the power conversion device described in Embodiment 1. One leg, consisting of multiple semiconductor modules, has a first semiconductor module arranged in the order of a high-potential conductive member, a semiconductor chip, and a low-potential conductive member, from one side to the other in the first direction, and a second semiconductor module arranged in the order of a high-potential conductive member, a semiconductor chip, and a low-potential conductive member. The second semiconductor module overlaps the first semiconductor module on the other side in the first direction, and the low-potential conductive member of the first semiconductor module and the high-potential conductive member of the second semiconductor module are fastened to each other at their respective terminals.

[0007] The power conversion device of Embodiment 3 is based on the power conversion device described in Embodiment 2. One leg of multiple semiconductor modules has a third semiconductor module arranged in the order of a high-potential conductive member, a semiconductor chip, and a low-potential conductive member, from one side to the other in the first direction, and a fourth semiconductor module arranged in the order of a high-potential conductive member, a semiconductor chip, and a low-potential conductive member. The fourth semiconductor module overlaps the third semiconductor module on the other side in the first direction, and the low-potential conductive member of the third semiconductor module and the high-potential conductive member of the fourth semiconductor module are fastened to each other at their respective terminals. The third semiconductor module overlaps the second semiconductor module on the other side in the first direction, and the low-potential conductive member of the second semiconductor module and the high-potential conductive member of the third semiconductor module are fastened to each other at their respective terminals.

[0008] The power conversion device of Embodiment 4 is based on the power conversion device described in Embodiment 3. The first semiconductor module and the fourth semiconductor module are diode modules, and the second semiconductor module and the third semiconductor module are switching element modules.

[0009] The power converter of embodiment 5 is based on the power converter described in any one of embodiments 1 to 4. The conductive members of a pair of semiconductor modules facing each other in the first direction are fastened together at the terminal portion in a state of surface contact with each other.

[0010] The power conversion device of embodiment 6 is based on the power conversion device described in any one of embodiments 1 to 5. The semiconductor module uses a conductive member located on at least one side of the semiconductor chip in the first direction as a heat sink. [Effects of the Invention]

[0011] According to the present invention, the number of connecting members between multiple semiconductor modules can be reduced. [Brief explanation of the drawing]

[0012] [Figure 1] Front cross-sectional view of the semiconductor module of the embodiment. [Figure 2] Front cross-sectional view of the area around the submodule. [Figure 3] Circuit diagram of the REG (regulator) of a power converter. [Figure 4] This diagram shows the switching element module of the embodiment in the upper section and the diode module in the lower section. [Figure 5] Plan view of the conductive member of the semiconductor module of the embodiment. [Figure 6] The lower panel of this front cross-sectional view shows the connection status of the semiconductor module in the power converter of Example 1, and the upper panel shows the connection status of the comparative example. [Figure 7] An explanatory diagram showing an example of a busbar connected to a conductive member of a semiconductor module according to an embodiment. [Figure 8] The lower panel shows the connection status of the semiconductor module in Example 2, and the upper panel shows the connection status of the semiconductor module in the comparative example. (Front cross-sectional view) [Figure 9] The lower panel shows the connection state of the semiconductor module pair in the modified example of Example 2, and the upper panel shows the connection state of the semiconductor module pair in the comparative example. [Modes for carrying out the invention]

[0013] The semiconductor module of the embodiment will be described below with reference to the drawings. Figure 1 is a front cross-sectional view of the semiconductor module 20 according to the first embodiment. As shown in FIG. 1, the semiconductor module 20 includes a top plate (conductive member) 21, a heat sink (conductive member) 22, and a semiconductor package 10P. The top plate 21 and the heat sink 22 are formed in a square or rectangular plate shape (see FIG. 5). The semiconductor package 10P includes a plurality of sub-modules 10.

[0014] In the present application, the Z direction (first direction), X direction, and Y direction in the orthogonal coordinate system are defined as follows. The Z direction is the direction in which the top plate 21 and the heat sink 22 are arranged. The +Z side is the side of the top plate 21 of the sub-module 10, and the -Z side is the side of the heat sink 22 of the sub-module 10. For example, the Z direction is the vertical direction, the +Z side is the upper side, and the -Z side is the lower side. In the Z direction, the side approaching the sub-module 10 may be referred to as the inner side, and the side departing from the sub-module 10 may be referred to as the outer side. The X direction and the Y direction are the directions in which the end sides of the top plate 21 and the heat sink 22 extend. For example, the X direction and the Y direction are the horizontal directions. In the X direction and the Y direction, the side approaching the center of the top plate 21 and the heat sink 22 may be referred to as the inner side, and the side departing from the center may be referred to as the outer side.

[0015] FIG. 2 is a front cross-sectional view of the periphery of the sub-module 10. As shown in FIG. 2, the sub-module 10 includes a semiconductor chip 15, a first electrode 11, and a second electrode 12. The semiconductor chip 15 is formed in a plate shape with the Z direction as the thickness direction. The semiconductor chip 15 is, for example, a transistor element such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), or a diode element such as an FRD (Fast Recovery Diode). A plurality of semiconductor chips 15 may be included in one sub-module 10.

[0016] The first electrode 11 and the second electrode 12 are formed of a metal material having high conductivity and thermal conductivity (for example, copper or aluminum, etc.). The first electrode 11 is disposed on the +Z side of the semiconductor chip 15, and the second electrode 12 is disposed on the -Z side. The first electrode 11 and the second electrode 12 are electrically connected to the semiconductor chip 15. A space that is inside the first electrode 11 and the second electrode 12 in the Z direction and where the semiconductor chip 15 does not exist is filled with a resin material having electrical insulation or the like. In the example of FIG. 2, an electrode conductor 14 is mounted on the +Z side of the first electrode 11.

[0017] The top plate 21 and the heat sink 22 are formed of a metal material having high conductivity and thermal conductivity (for example, copper or aluminum, etc.). The top plate 21 is disposed on the +Z side of the sub-module 10, and the heat sink 22 is disposed on the -Z side. The top plate 21 and the heat sink 22 are electrically connected to the semiconductor chip 15 via the first electrode 11 and the second electrode 12 of the sub-module 10.

[0018] From the +Z side of the top plate 21, a bolt 24 is inserted into a through hole formed in the top plate 21. The tip of the bolt 24 is screwed into a female screw formed in the electrode conductor 14 of the sub-module 10. The heat sink 22 is fixed to the second electrode 12 of the sub-module 10 by a bolt or the like (not shown).

[0019] The heat sink 22 has a heat sink body 22a and a heat sink cover 22b. A groove (not shown) is formed on the surface of the -Z side of the heat sink body 22a. The heat sink cover 22b is disposed on the -Z side of the heat sink body 22a and closes the groove. A cooling fluid circulates between the outside of the heat sink 22 and the inside of the groove. By the cooling fluid flowing through the inside of the groove, the semiconductor chip 15 is cooled.

[0020] As shown in Figure 1, the semiconductor module 20 has a plurality of submodules 10. The plurality of submodules 10 are connected in parallel by a top plate 21 and a heat sink 22. An electrically insulating resin member 25 is filled between the plurality of submodules 10 on the inside of the top plate 21 and heat sink 22 in the Z direction. On the inside of the top plate 21 and heat sink 22 in the Z direction, side walls (not shown) made of an electrically insulating resin material or the like are formed around the periphery in the X and Y directions.

[0021] Figure 3 is a circuit diagram of leg 60 of power converter 1. As shown in Figure 3, the power converter 1 is configured by connecting multiple legs 60. A leg 60 is a constituent unit of the power converter 1. In a leg 60, a first unit 61 and a second unit 62 are connected in series. In the first unit 61, a transistor element 15b and a diode element 15a are connected in parallel. In the second unit 62, a transistor element 15c and a diode element 15d are connected in parallel.

[0022] Figure 4 is an explanatory diagram showing the switching element module 17 in the upper part and the diode module 18 in the lower part of the embodiment. The switching element module 17 and the diode module 18 are examples of semiconductor modules 20. The switching element module 17 has a configuration in which a submodule 10 (switching element package), in which a transistor element (switching element) is sealed with a resin material (insulating material), is sandwiched between metal materials (conductive materials) 21 and 22. The diode module 18 has a configuration in which a submodule 10 (diode package), in which a diode element is sealed with a resin material (insulating material), is sandwiched between metal materials (conductive materials) 21 and 22.

[0023] As shown in the upper part of Figure 4, the switching element module 17 has a metal member (conductive member, e.g., heat sink 22) on the high-potential side of the current conduction path, and a metal member (conductive member, e.g., top plate 21) on the low-potential side of the current conduction path, with an insulating member (switching element package) interposed between the two metal members. Both metal members and the insulating member are stacked in the Z direction. In the switching element module 17 of Figure 4, current flows from the upper side (high potential side) to the lower side (low potential side) in the figure (see arrow E1).

[0024] As shown in the lower part of Figure 4, the diode module 18 has a metal component (conductive component, e.g., top plate 21) on the high-potential side of the current conduction path, and a metal component (conductive component, e.g., heat sink 22) on the low-potential side of the current conduction path, with an insulating component (diode package) interposed between the two metal components. Both metal components and the insulating component are stacked in the Z direction. In the diode module 18 of Figure 4, current flows from the lower side (high potential side) to the upper side (low potential side) in the figure (see arrow E2).

[0025] Figure 5 is a plan view (viewed from the stacking direction, which will be described later) of the metal components (conductive components) 21 and 22 of the semiconductor module 20. As shown in Figure 5, the metal members 21 and 22 are a top plate 21 and a heat sink 22, and are formed in the shape of a square or rectangular plate in plan view. Both sides of the plan view shape of the metal members are a pair of terminal edges 27 that can be fastened to the metal members of other semiconductor modules facing each other in the first direction. Each terminal edge 27 has a plurality of terminal portions 27a arranged along each side edge 27c on both sides of the plan view shape. Each terminal portion 27a has, for example, a circular through hole 27b in plan view.

[0026] <Example 1> Figure 6 is a front cross-sectional view showing the connection state of the semiconductor module of the power converter 1 in the first embodiment (Embodiment 1) in the lower panel, and the connection state of the comparative example in the upper panel. As shown in Figure 6, the leg 60 of the embodiment is configured by connecting a plurality of semiconductor modules 20. The plurality of semiconductor modules 20 are arranged in the Z direction from bottom to top in the figure, and include a first semiconductor module 20a, a second semiconductor module 20b, a third semiconductor module 20c, and a fourth semiconductor module 20d. The semiconductor chip 15 of the first semiconductor module 20a is the diode element 15a of the first unit 61. The semiconductor chip 15 of the second semiconductor module 20b is the transistor element 15b of the first unit 61. The semiconductor chip 15 of the third semiconductor module 20c is the transistor element 15c of the second unit 62. The semiconductor chip 15 of the fourth semiconductor module 20d is the diode element 15d of the second unit 62. In Figure 6 (and in Figures 8 and 9 described later), the resin member (insulating member) 25 that each semiconductor module 20 provides between the top plate 21 and the heat sink 22 is not shown. Hereafter, the first semiconductor module 20a may be referred to as the diode module 20a, and the second semiconductor module 20b may be referred to as the switching element module 20b. Similarly, the third semiconductor module 20c may be referred to as the switching element module 20c, and the fourth semiconductor module 20d may be referred to as the diode module 20d.

[0027] Leg 60 has busbars 31 and 32. The busbars 31 and 32 are made of a metallic material (e.g., copper or aluminum) that has high electrical and thermal conductivity. The busbars 31 and 32 are positioned outside the X or Y direction of the plurality of semiconductor modules 20. The busbars 31 and 32 are formed in a U shape. The busbars 31 and 32 are a first busbar 31 and a second busbar 32. The first busbar 31 is positioned with its U-shaped opening facing the first semiconductor module 20a and the second semiconductor module 20b. The second busbar 32 is positioned with its U-shaped opening facing the third semiconductor module 20c and the fourth semiconductor module 20d.

[0028] In Figure 6, the first semiconductor module 20a and the second semiconductor module 20b are positioned with their respective heat sinks 22 facing each other. The heat sink 22 of the first semiconductor module 20a and the heat sink 22 of the second semiconductor module 20b are in contact with each other. The terminal portions 27a of both heat sinks 22 are fastened together with bolts 28 (see Figure 7), connecting them mechanically and electrically.

[0029] The lower end of the first busbar 31 in the figure and the top plate 21 of the first semiconductor module 20a are in contact with each other. The two in contact are fastened together by bolts 28 and are mechanically and electrically connected. The upper end of the first busbar 31 in the figure and the top plate 21 of the second semiconductor module 20b are in contact with each other. The two in contact are fastened together by bolts 28 and are mechanically and electrically connected. Because the first busbar 31 is U-shaped, it straddles the connection portion 29 that connects the two heat sinks 22 of the first semiconductor module 20a and the second semiconductor module 20b, making it easy to secure an insulating distance from the connection portion. As a result, the first semiconductor module 20a and the second semiconductor module 20b are connected in parallel, forming the first unit 61 of leg 60.

[0030] The upper arm 31a of the U-shaped first busbar 31 can be integrated with the lower arm 32a of the U-shaped second busbar 32, which connects the third semiconductor module 20c and the fourth semiconductor module 20d (see lower part of Figure 6), thus reducing the number of connecting members compared to the comparative example. On the side opposite the first busbar 31 in the X direction (left-right direction in the figure), the terminal portions 27a of both heat sinks 22 of the first semiconductor module 20a and the second semiconductor module 20b are directly fastened together with bolts 28. This allows the U-shaped connecting member 33 (see upper part of Figure 6) connecting the two heat sinks 22 to be replaced with an I-shaped connecting member 33a (see lower part of Figure 6), thereby reducing the amount of material used.

[0031] In Figure 6, the third semiconductor module 20c and the fourth semiconductor module 20d are arranged with their top plates 21 facing each other. The top plate 21 of the third semiconductor module 20c and the top plate 21 of the fourth semiconductor module 20d are in contact with each other. The terminal portions 27a of both top plates 21 are fastened together with bolts 28, connecting them mechanically and electrically.

[0032] The lower end of the second busbar 32 in the figure and the heatsink 22 of the third semiconductor module 20c are in contact with each other. The two in contact are fastened together by bolts 28 and are mechanically and electrically connected. The upper end of the second busbar 32 in the figure and the heatsink 22 of the fourth semiconductor module 20d are in contact with each other. The two in contact are fastened together by bolts 28 and are mechanically and electrically connected. Because the second busbar 32 is U-shaped, it straddles the connection portion 29 of both top plates 21, making it easy to secure an insulating distance from the connection portion. As a result, the third semiconductor module 20c and the fourth semiconductor module 20d are connected in parallel, forming the second unit 62 of leg 60.

[0033] The lower arm portion 32a of the U-shaped second busbar 32 can be integrated with the upper arm portion 31a of the U-shaped first busbar 31 (see lower part of Figure 6), which allows for a reduction in the material of the connecting members 31 and 32 compared to the comparative example. On the side opposite the second busbar 32 in the X direction (left-right direction in the figure), the terminal portions 27a of both top plates 21 of the third semiconductor module 20c and the fourth semiconductor module 20d are directly fastened together with bolts 28. This allows the U-shaped connecting member 34 (see upper part of Figure 6) connecting the two top plates 21 to be replaced with an I-shaped connecting member 34a (see lower part of Figure 6), thereby reducing the amount of material used.

[0034] The upper top plate 21 of the second semiconductor module 20b and the lower heat sink 22 of the third semiconductor module 20c are in contact with each other. The two contacting parts are fastened together by bolts 28, creating a mechanical and electrical connection. In addition to the top plate 21 of the second semiconductor module 20b and the heat sink 22 of the third semiconductor module 20c, the upper end of the first busbar 31 and the lower end of the second busbar 32 may also be fastened together by bolts 28 at this connection point 29. As described above, the first unit 61 and the second unit 62 are connected in series to form leg 60. Since the leg 60 is formed by stacking the semiconductor modules 20 in the Z direction, the power converter 1 can be easily miniaturized.

[0035] The mechanical connections of the semiconductor module 20 will be described. Figure 5 shows the shape (plan view) of the upper and lower metal members 21 and 22 of the semiconductor module 20 as seen from the Z direction (stacking direction). As shown in Figure 5, the upper and lower metal members 21 and 22 serve as the lid and bottom of the semiconductor package, while also having terminal portions 27a for connecting to other semiconductor modules 20. If a pair of metal members 21 and 22 facing each other in the Z direction are at the same potential, their respective surfaces are brought into contact with each other, and bolts 28 are inserted through the through holes 27b and fastened with nuts or the like. This makes it possible to achieve low impedance. Furthermore, even when connecting metal members 21 and 22 that do not face each other in the Z direction, the impedance can be controlled with a high degree of flexibility in layout by connecting them using busbars via the through holes 27b (see Figure 7).

[0036] Figure 6 shows an example of the power converter 1 that constitutes one leg 60 in Figure 3, with the upper section showing a comparative example and the lower section showing Example 1. As shown in Figure 6, a semiconductor module 20 for one leg consists of the first semiconductor module 20a, the second semiconductor module 20b, the third semiconductor module 20c, and the fourth semiconductor module 20d, stacked vertically from bottom to top in the figure. When metal members 21 and 22 of the same potential are connected by busbars, the configuration is as shown in the upper part of Figure 6. However, when opposing modules are fastened together at the terminal portions 27a of the metal members 21 and 22, the configuration is as shown in the lower part of Figure 6. In other words, as shown in the lower part of Figure 6, a portion of the busbar is eliminated, making the configuration more compact, and since the metal members 21 and 22 of the same potential are in direct contact (surface contact) with the opposing modules, low impedance can be achieved.

[0037] Figure 7 is an explanatory diagram of the wiring and fastening parts of the busbar shown in Figure 6. As shown in Figure 7, one method of controlling impedance is to utilize the width of the busbar fastened to the through-hole 27b of the metal member. For example, as shown in the upper part of Figure 7, by narrowing the width of the busbar 30a by having only one fastening point, the input and output of current can be limited to a single point. For example, as shown in the lower part of Figure 7, there is also a method of not restricting the current path by widening the width of the busbar 30b with three fastening points. Restricting the current path restricts the current path of multiple semiconductor chips 15 arranged in parallel within the package, and the current balance can be controlled.

[0038] <Example 2> Next, a second embodiment (Example 2) of the embodiment will be described. Figure 8 shows an example of the power converter 1 (indicated by reference numeral 1') that constitutes leg 60 of Figure 3 in Example 2, with the upper row showing a comparative example and the lower row showing the example. As shown in Figure 8, in Example 2, the upper and lower positions of the lower semiconductor modules 20a and 20b are swapped compared to the configuration in Figure 6 of Example 1. That is, in Figure 8, the semiconductor elements for one leg are stacked vertically from bottom to top in the figure: the second semiconductor module 20b, the first semiconductor module 20a, the third semiconductor module 20c, and the fourth semiconductor module 20d. In this case, the first semiconductor module 20a and the third semiconductor module 20c are not at the same potential, so the opposing modules are not connected by a surface but by an additional component such as a busbar. The modules within each arm of one leg are connected by direct surface contact between metal components at the same potential, using the shortest possible connection. The upper and lower arms are connected via an additional component. This configuration can be used when the inductance within each arm is suppressed, while the inductance between the upper and lower arms is desired. Increasing the inductance between the upper and lower arms has the effect of suppressing the short-circuit energy in the event of a short-circuit fault.

[0039] The first semiconductor module 20a and the second semiconductor module 20b are connected by multiple connection points 29a using chip cases 35a and 35b, which will be described later, and the third semiconductor module 20c and the fourth semiconductor module 20d are also connected by multiple connection points 29a. In the comparative example, the lower end 31b of the first busbar 31 in the figure is further formed in a U-shape and connected to the top plates 21 of the second semiconductor module 20b and the first semiconductor module 20a. In the second embodiment, the top plates 21 of the second semiconductor module 20b and the first semiconductor module 20a are connected to each other by a connecting portion 29a. In the second embodiment, the lower end 31c of the first busbar 31 in the figure is formed in an I-shape, which allows for a reduction in material.

[0040] The top surface of the switching element module 20b and the bottom surface of the diode module 20a in Figure 8 serve the same purpose (both are top plates 21 in Figure 8), and the top surface of the switching element module 20c and the bottom surface of the diode module 20d serve the same purpose (both are top plates 21 in Figure 8). Therefore, by combining these modules, it becomes possible to modify the design by using a pair of opposing top plates 21 as common components.

[0041] Figure 9 is a front cross-sectional view showing the modified semiconductor module pair described above in the lower section and the comparative semiconductor module pair in the upper section. In the example in the lower section of Figure 9, the above-mentioned common components are used on the upper surface of the switching element module 20b and the lower surface of the diode module 20a, but the above-mentioned common components can also be used on the upper surface of the switching element module 20c and the lower surface of the diode module 20d. Reference numeral 20a' in the figure indicates a diode module in which the lower component (top plate 21) has been eliminated by sharing it with the upper component (top plate 21) of the switching element module 20b.

[0042] In the lower example of Figure 9, the chip case 35b (containing the semiconductor chip 15 on the switching element side) sealed within the switching element module 20b and the chip case 35a (containing the semiconductor chip 15 on the diode side) sealed within the diode module 20a' are assembled together as a single unit. In this case, the chip case 35b of the switching element module 20b and the chip case 35a of the diode module 20a' are positioned facing each other and assembled so that the conductors (electrode conductors 14) of each chip case 35a and 35b are in contact with each other.

[0043] In other words, in the lower example of Figure 9, at the connection point 29a, the components are stacked in the following order from bottom to top in the figure: the conductor of the chip case 35b of the switching element module 20b, the top plate 21 (a single common component) of the switching element module 20b, and the conductor of the chip case 35a of the diode module 20a'. Then, the chip case 35a of the diode module 20a', the top plate 21 (a single common component), and the chip case 35b of the switching element module 20b can be fastened together using bolts 28 and nuts, as shown in the lower part of Figure 9. When fastening, a certain width (working space) is required between the top plate 21 and each chip case. This width needs to be, for example, higher than the height of the bolt head. In the enlarged view A at the bottom of Figure 9, the distance between the lower chip case 35b and the top plate 21 is close, while the distance between the upper chip case 35a and the top plate 21 is far. In the enlarged view B at the bottom of Figure 9, the position of the top plate 21 is set to the center between the upper and lower chip cases 35a and 35b. In enlarged view B, by setting the common position of the top plate 21 to the center between the upper and lower chip cases 35a and 35b, the distance from each chip case 35a and 35b to the top plate 21 becomes equal.

[0044] As detailed above, the power converter 1 of the embodiment has a plurality of semiconductor modules 20 stacked in the first direction. Each semiconductor module 20 has a semiconductor chip 15 and metal members 21, 22 positioned on at least one side of the semiconductor chip 15 in the first direction. The metal members 21, 22 have terminal portions 27a that can be fastened to metal members 21, 22 of other semiconductor modules 20 facing each other in the first direction.

[0045] In the power conversion device 1 of the embodiment, one leg 60 made up of multiple semiconductor modules 20 has a first semiconductor module 20a arranged in the order of a high-potential conductive member, a semiconductor chip 15, and a low-potential conductive member, in the order of a high-potential conductive member, a semiconductor chip 15, and a low-potential conductive member, and a second semiconductor module 20b arranged in the order of a high-potential conductive member, a semiconductor chip 15, and a low-potential conductive member. The second semiconductor module 20b overlaps the first semiconductor module 20a on the other side in the first direction, and the conductive member on the low-potential side of the first semiconductor module 20a and the conductive member on the high-potential side of the second semiconductor module 20b are fastened to each other at their respective terminal portions 27a.

[0046] In the power converter 1 of the embodiment, one leg 60 made up of multiple semiconductor modules 20 has a third semiconductor module 20c arranged in the order of a high-potential conductive member, a semiconductor chip 15, and a low-potential conductive member, in the order of a high-potential conductive member, a semiconductor chip 15, and a low-potential conductive member, and a fourth semiconductor module 20d arranged in the order of a high-potential conductive member, a semiconductor chip 15, and a low-potential conductive member. The fourth semiconductor module 20d overlaps the third semiconductor module 20c on the other side in the first direction, and the conductive member on the low-potential side of the third semiconductor module 20c and the conductive member on the high-potential side of the fourth semiconductor module 20d are fastened to each other at their respective terminal portions 27a. The third semiconductor module 20c overlaps the second semiconductor module 20b in the first direction, and the conductive member on the low-potential side of the second semiconductor module 20b and the conductive member on the high-potential side of the third semiconductor module 20c are fastened to each other at their respective terminal portions 27a.

[0047] According to the above configuration, the conductive members of semiconductor modules 20 facing each other in the stacking direction can be directly fastened together, thereby reducing the number of connecting members between multiple semiconductor modules 20. Furthermore, the impedance within one leg 60 of the power converter 1 can be reduced, costs can be suppressed, miniaturization can be achieved, and a configuration (structure) with a high degree of layout flexibility can be achieved.

[0048] The power converter 1 of this embodiment does not use a pressure-contact structure, but has a structure that maintains a short circuit and does not cause secondary damage. Specifically, each of the upper and lower arms is configured as a switching element module 17 and a diode module 18, and these are stacked vertically to form one leg. Unlike the pressure-contact type, in order to connect opposing semiconductor modules 20 in the shortest possible time, the conductive members that act as lids (e.g., top plate 21) and bottoms (e.g., heat sink 22) on the upper and lower surfaces of the semiconductor package (submodule 10) have terminal portions 27a that can be fastened to other semiconductor modules 20. The terminal portions 27a enable the connection of opposing semiconductor modules 20 to each other. There are multiple terminal portions 27a, and in addition to connecting opposing semiconductor modules 20 to each other, they also serve as terminals for connecting semiconductor modules 20 that do not directly face each other via busbars, etc. By not using a pressure-contact type package, stacking costs are reduced, the processing precision of the contact surface unique to pressure-contact type packages is not required, and the assembly of the power converter 1 can be made easier.

[0049] The power converter 1 of this embodiment can utilize the electrical characteristics of a semiconductor chip 15 to near its limits, even with a high-capacity module, similar to a medium- or low-capacity module. In other words, with a high-capacity module, if the switching element and the antiparallel diode are sealed in a single package on one arm, the package becomes too large, and the electrical characteristics of the semiconductor chip 15 cannot be fully utilized. On the other hand, if the switching element and the antiparallel diode are packaged separately and stacked vertically, it is common to connect the packages with additional components such as busbars, but the impedance of the additional components prevents the electrical characteristics of the semiconductor chip 15 from being fully utilized. When the packages are separate, there is also a configuration using pressure bonding, but the entire system becomes large due to the pressure bonding mechanism, and the processing precision of the pressure bonding surface and components is required, which limits the applications and increases costs.

[0050] In this embodiment, the power converter 1 separates the switching element and the antiparallel diode into different packages. The conductive member that acts as the lid and bottom of the package has a terminal portion 27a for connection. Therefore, no additional connection members are required for the package within one leg. For example, in one leg, the diode module 20a (lower arm), switching element module 20b (lower arm), switching element module 20c (upper arm), and diode module 20d (upper arm) are stacked vertically from one side (bottom) to the other side (top) in the stacking direction (Example 1). This reduces the number of additional members other than the package, making wiring possible. For example, in a stack of pressure-contact packages, in addition to the pressure-contact package and conductive members such as a heat sink, a conductive member for the terminal is stacked vertically, but in this embodiment, the conductive member for the terminal is not required. In this way, even if the semiconductor module 20 is large, the impedance within one leg can be reduced, and the electrical characteristics of the semiconductor chip 15 can be used to their limits. Since additional components such as busbars can be reduced within one leg, costs can be lowered.

[0051] In the power conversion device 1 of this embodiment, the first semiconductor module 20a and the fourth semiconductor module 20d are diode modules 18, and the second semiconductor module 20b and the third semiconductor module 20c are switching element modules 17. Multiple semiconductor modules 20, separated by function, can be efficiently connected.

[0052] In the power converter 1 of this embodiment, the conductive members 21 and 22 of a pair of semiconductor modules 20 facing each other in the first direction are fastened together at the terminal portion 27a while in surface contact with each other. By fastening the conductive members of the pair of semiconductor modules 20 in surface contact with each other, a connection method can be achieved that reduces the impedance between the pair of semiconductor modules 20.

[0053] In the power conversion device 1 of this embodiment, the semiconductor module 20 has a heat sink 22 which is a conductive member located on at least one side of the semiconductor chip 15 in the first direction. The semiconductor module 20 is configured with the heat sink 22 as an integrated unit, allowing the electrical characteristics of the semiconductor chip 15 to be fully utilized.

[0054] According to at least one embodiment described above, the conductive member of the semiconductor module 20 has a terminal portion 27a that can be fastened to the conductive member of another semiconductor module 20 facing in the first direction, thereby enabling direct fastening of the conductive members of semiconductor modules 20 facing each other in the stacking direction, and reducing the number of connecting members between multiple semiconductor modules 20.

[0055] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0056] 1,1' ... Power converter, 15 ... Semiconductor chip, 17 ... Switching element module, 18 ... Diode module, 20 ... Semiconductor module, 20a ... First semiconductor module, 20b ... Second semiconductor module, 20c ... Third semiconductor module, 20d ... Fourth semiconductor module, 21 ... Top plate (conductive material), 22 ... Heat sink (conductive material), 27a ... Terminal section, 60 ... Leg

Claims

1. It comprises multiple semiconductor modules stacked in the first direction, The semiconductor module comprises a semiconductor chip and a conductive member disposed on at least one side of the semiconductor chip in a first direction. The conductive member is provided with a terminal portion that can be fastened to the conductive member of another semiconductor module facing in the first direction. Power converter.

2. Each leg of the plurality of semiconductor modules comprises a first semiconductor module arranged in the order of the high-potential conductive member, the semiconductor chip, and the low-potential conductive member, in the order of the high-potential conductive member, the semiconductor chip, and the low-potential conductive member, respectively, in the order of the high-potential conductive member, the semiconductor chip, and the low-potential conductive member, The second semiconductor module overlaps the first semiconductor module on the other side in the first direction, and the conductive member on the low-potential side of the first semiconductor module and the conductive member on the high-potential side of the second semiconductor module are fastened together at their respective terminal portions. The power conversion device according to claim 1.

3. Each leg of the plurality of semiconductor modules comprises a third semiconductor module arranged in the order of the high-potential conductive member, the semiconductor chip, and the low-potential conductive member, in the order of the high-potential conductive member, the semiconductor chip, and the low-potential conductive member, in the order of the high-potential conductive member, the semiconductor chip, and the low-potential conductive member, respectively. The fourth semiconductor module overlaps the third semiconductor module on the other side in the first direction, and the conductive member on the low-potential side of the third semiconductor module and the conductive member on the high-potential side of the fourth semiconductor module are fastened to each other at their respective terminal portions. The third semiconductor module overlaps the second semiconductor module on the other side in the first direction, and the conductive member on the low-potential side of the second semiconductor module and the conductive member on the high-potential side of the third semiconductor module are fastened together at their respective terminal portions. The power conversion device according to claim 2.

4. The first semiconductor module and the fourth semiconductor module are diode modules, and the second semiconductor module and the third semiconductor module are switching element modules. The power conversion device according to claim 3.

5. The conductive members of the pair of semiconductor modules facing each other in the first direction are fastened together at the terminal portion in a state of surface contact with each other. The power conversion device according to claim 1 or 2.

6. The semiconductor module uses the conductive member, which is positioned on at least one side of the semiconductor chip in the first direction, as a heat sink. The power conversion device according to claim 1 or 2.

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