Power conversion device and semiconductor element pressing mechanism

Abstract

This power conversion device comprises a principal circuit board that has a principal circuit board front surface on which a semiconductor element is installed and a principal circuit board back surface that is on the reverse side from the principal circuit board front surface, a cooling part that is provided on the principal circuit board front surface side so as to be opposite the semiconductor element and dissipates heat produced from the semiconductor element, and a pressing part that presses the semiconductor element from the principal circuit board back surface side toward the cooling part side.

Description

Power conversion device and semiconductor element pressing mechanism

[0001] This invention relates to a power conversion device and a semiconductor element pressing mechanism, and particularly to a power conversion device and a semiconductor element pressing mechanism provided with a cooling unit.

[0002] Conventionally, a power conversion device provided with a cooling unit is known. Such a power conversion device is disclosed in, for example, International Publication No. 2024 / 143541.

[0003] International Publication No. 2024 / 143541 discloses a power conversion device including a main circuit board on which semiconductor elements for converting power are arranged, and a cooling unit arranged to face the semiconductor elements and radiating heat generated from the semiconductor elements, wherein an outer edge portion of the main circuit board is fixed to the cooling unit by a fastening member. Heat generated from the semiconductor elements is radiated by contact between the surface of this cooling unit and the surface of the semiconductor elements.

[0004] International Publication No. 2024 / 143541

[0005] In the power conversion device described in International Publication No. 2024 / 143541, since the outer edge portion of the main circuit board is fixed to the cooling unit by a fastening member, when there is warping or deflection in the main circuit board, contact between the surface of the cooling unit and the surface of the semiconductor elements may become insufficient in the vicinity of the semiconductor elements arranged at locations away from the fastening portion of the main circuit board. When the contact between the surface of the cooling unit and the surface of the semiconductor elements becomes insufficient, the heat dissipation performance of the heat generated from the semiconductor elements by the cooling unit deteriorates, which is not desirable for the stable operation of the semiconductor elements. Therefore, there is a need for a power conversion device and a semiconductor element pressing mechanism capable of suppressing a decrease in the heat dissipation performance of the heat generated from the semiconductor elements by the cooling unit even when there is warping or deflection in the main circuit board.

[0006] This invention has been made to solve the above problems, and one object of this invention is to provide a power conversion device and a semiconductor element pressing mechanism capable of suppressing a decrease in the heat dissipation performance of the heat generated from the semiconductor elements by the cooling unit even when there is warping or deflection in the main circuit board.

[0007] To achieve the above objective, the power conversion device according to the first aspect of this invention comprises a main circuit board having a main circuit board surface on which semiconductor elements for power conversion are arranged, and a main circuit board back surface which is the surface opposite to the main circuit board surface; a cooling unit disposed on the main circuit board surface side so as to face the semiconductor elements and for dissipating heat generated from the semiconductor elements; and a pressing unit for pressing the semiconductor elements from the main circuit board back surface side toward the cooling unit.

[0008] In the power conversion device according to the first aspect of this invention, as described above, a pressing part is provided that presses the semiconductor element toward the cooling part from the back side of the main circuit board. As a result, the semiconductor element is pressed toward the cooling part by the pressing part, so even if there is warping or bending of the main circuit board, it is possible to suppress insufficient contact between the surface of the cooling part and the surface of the semiconductor element. As a result, even if there is warping or bending of the main circuit board, it is possible to suppress a decrease in the heat dissipation performance of the heat generated from the semiconductor element by the cooling part.

[0009] In the power conversion device according to the first aspect described above, preferably, the pressing portion is configured to press from the back side of the main circuit board the portion of the back surface of the main circuit board that overlaps with the portion where the semiconductor elements are arranged, when viewed from the thickness direction of the main circuit board. With this configuration, when viewed from the thickness direction of the main circuit board, the portion of the back surface of the main circuit board that overlaps with the portion where the semiconductor elements are arranged can be pressed, so even if there is warping or bending in the main circuit board, the semiconductor elements can be made to contact the cooling portion more reliably.

[0010] In the power conversion device according to the first aspect described above, the pressing part is preferably a leaf spring. Here, in order to properly press the semiconductor element from the back side of the main circuit board to the cooling part side using a pressing part made of a rigid body, it is necessary to manufacture the pressing part with high precision. However, if the pressing part is a leaf spring, the semiconductor element is pressed to the cooling part side by the deformation of the leaf spring, so the manufacturing of a pressing part using a leaf spring does not require the same level of precision as when using a pressing part made of a rigid body. As a result, by using a leaf spring for the pressing part, the semiconductor element can be pressed to the cooling part side more easily.

[0011] In the power conversion device according to the first aspect described above, preferably, a control board is located on the back side of the main circuit board and controls semiconductor elements, and a control board fixing part is located between the cooling part and the control board and fixes the control board, with the pressing part provided on the control board fixing part. With this configuration, the control board can be fixed by the control board fixing part on which the pressing part is provided, so the power conversion device can be made more space-efficient compared to the case where the pressing part and the control board fixing part are located in separate places.

[0012] In this case, preferably, the control board fixing portion is provided with a plurality of control board fixing bosses that protrude toward the control board and fix the control board, and the pressing portion is provided inside the plurality of control board fixing bosses when viewed from the thickness direction of the main circuit board. With this configuration, the control board can be separated from the mounting surface of the control board fixing portion to which the control board is attached by the control board fixing bosses. As a result, an air passage can be secured between the control board and the mounting surface, making it possible to efficiently cool the control board. In addition, by separating the main circuit board and the control board, insulation between the main circuit board and the control board can be ensured. Furthermore, since the pressing portion is provided inside the plurality of control board fixing bosses when viewed from the thickness direction of the main circuit board, it is possible to suppress the size increase of the power conversion device.

[0013] In a power converter provided with a plurality of control board fixing bosses that protrude toward the control board and fix the control board, preferably, the control board fixing portion includes a fixing plate on which the control board fixing bosses are provided, and the pressing portion is provided integrally with the fixing plate. With this configuration, the control board can be fixed on the fixing plate on which the control board fixing bosses are provided, so that the control board can be fixed while being reinforced by the fixing plate. Furthermore, because the pressing portion is provided integrally with the fixing plate, it is possible to suppress an increase in the number of parts of the power converter and to suppress an increase in the complexity of the structure of the power converter.

[0014] In this case, preferably, the fixing plate has a frame portion, and the pressing portion is integrally provided with the fixing plate so as to protrude inward from the frame portion and also protrude from the fixing plate toward the main circuit board side. With this configuration, since the pressing portion is provided so as to protrude toward the main circuit board side, even if the pressing portion is integrally provided with the fixing plate, the semiconductor element can be reliably pressed toward the cooling portion by the pressing portion.

[0015] In a power conversion device including a fixing plate provided with bosses for fixing the control board, the control board fixing portion is preferably integrally provided on the fixing plate so as to connect two opposing sides of the frame portion of the fixing plate. With this configuration, the two opposing sides of the frame portion are integrally connected by the pressing portion, thereby improving the mechanical strength of the fixing plate.

[0016] The above-described control board fixing portion is a power conversion device that includes a fixing plate provided with bosses for fixing the control board. Preferably, the fixing plate has a frame portion, the bosses for fixing the control board further include bosses for fixing the control board on the surface of the frame portion, the fixing plate is arranged inside the frame portion and includes bosses for fixing the control board inside the frame portion which protrude toward the control board and fix the control board, and the pressing portion is provided inside the frame portion. With this configuration, the control board can be fixed by the bosses for fixing the control board on the surface of the frame portion of the fixing plate, as well as the bosses for fixing the control board inside the frame portion which are provided inside the frame portion. As a result, the number of fixing points of the control board on the fixing plate can be increased, and the fixing strength of the control board to the fixing plate can be improved.

[0017] In this case, preferably, the frame portion has connecting portions that connect two opposing sides of the frame portion, and the bosses for fixing the control board within the frame are provided on the connecting portions. With this configuration, the strength of the fixing plate can be improved by the connecting portions that connect two opposing sides of the frame portion. In addition, by providing the bosses for fixing the control board within the frame on the connecting portions, the number of fixing points of the control board on the fixing plate can be increased, thereby improving the fixing strength of the control board to the fixing plate.

[0018] In a power conversion device having a frame, the fixing plate described above preferably has the boss for fixing the control board within the frame provided on the surface of the pressing portion on the control board side. With this configuration, it is not necessary to provide the pressing portion and the boss for fixing the control board within the frame in different locations, thus enabling space saving in the power conversion device.

[0019] In the power conversion device according to the first aspect described above, preferably, the surface of the main circuit board has a plurality of semiconductor elements arranged therein, and the plurality of semiconductor elements are arranged side by side, and the pressing part is configured to press the plurality of semiconductor elements toward the cooling part from the back side of the main circuit board along the direction in which the plurality of semiconductor elements are arranged side by side. With this configuration, the plurality of semiconductor elements can be pressed toward the cooling part from the back side of the main circuit board along the direction in which the plurality of semiconductor elements are arranged side by side, so that the surfaces of the plurality of semiconductor elements can be brought into contact with the surface of the cooling part. As a result, the decrease in the heat dissipation performance of the cooling part from the plurality of semiconductor elements can be suppressed.

[0020] A semiconductor element pressing mechanism according to the second aspect of this invention comprises a pressing part that presses a semiconductor element, which is arranged on a main circuit board having a main circuit board surface on which a power-converting semiconductor element is arranged, toward a cooling part that dissipates heat generated from the semiconductor element, from the back side of the main circuit board, toward the main circuit board side facing the semiconductor element.

[0021] The semiconductor element pressing mechanism according to the second aspect of this invention includes a pressing part that presses the semiconductor element toward a cooling part that dissipates heat generated from the semiconductor element. As a result, the semiconductor element is pressed toward the cooling part by the pressing part, so even if there is warping or bending in the main circuit board, it is possible to suppress insufficient contact between the surface of the cooling part and the surface of the semiconductor element. Consequently, even if there is warping or bending in the main circuit board, it is possible to suppress a decrease in the heat dissipation performance of the cooling part from the heat generated from the semiconductor element.

[0022] According to the present invention, as described above, it is possible to provide a power conversion device that can suppress the decrease in the heat dissipation performance of the cooling unit from semiconductor elements, even when there is warping or bending in the main circuit board.

[0023] This is a perspective view of a power converter according to the first embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to the first embodiment of the present invention along the line II-II in Figure 1. This is a perspective view of a power converter according to the second embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to the second embodiment of the present invention along the line IV-IV in Figure 3. This is a perspective view of a power converter according to the third embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to the third embodiment of the present invention along the line VI-VI in Figure 5. This is a perspective view of a power converter according to the fourth embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to the fourth embodiment of the present invention along the line VIII-VIII in Figure 7. This is a perspective view of a power converter according to the fifth embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to the fifth embodiment of the present invention along the line X-X in Figure 9. This is a perspective view of a power converter according to the first modification of the first embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to the first modification of the first embodiment of the present invention along the line XII-XII in Figure 11. This is a perspective view of a power converter according to a second modification of the first embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to a second modification of the first embodiment of the present invention, along the line XIV-XIV in Figure 13. This is a perspective view of a power converter according to a third modification of the first embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to a third modification of the first embodiment of the present invention, along the line XVI-XVI in Figure 15. This is a perspective view of a power converter according to a second modification of the second embodiment of the present invention, with the housing and control board omitted. This is a perspective view of a power converter according to a third modification of the third embodiment of the present invention, with the housing and control board omitted. This is a perspective view of a power converter according to a fourth modification of the first embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to a fourth modification of the first embodiment of the present invention, along the line XXI-XXI in Figure 20.This is a perspective view of a power converter according to a fifth modification of the first embodiment of the present invention, with the housing and control board omitted. This is a cross-sectional view of the power converter according to a fifth modification of the first embodiment of the present invention, along the line XXIII-XXIII in Figure 22.

[0024] The following describes embodiments of the present invention based on the drawings.

[0025] [First Embodiment] The configuration of the power conversion device 100 according to the first embodiment of the present invention will be described with reference to Figures 1 and 2. In Figure 1, for the sake of clarity, the control board 3 and the housing 5 are omitted from the diagram. Figure 2 is a cross-sectional view taken along the line II-II shown in Figure 1.

[0026] (Configuration of the power converter) As shown in Figures 1 and 2, the power converter 100 according to the first embodiment comprises a main circuit board 1, a cooler 2, a control board 3, a fixing plate 4, and a housing 5. Here, the cooler 2 is an example of the "cooling unit" in the claims. Hereafter, the direction along the long side of the rectangular main circuit board 1 in the figures will be referred to as the X direction, the direction along the short side of the rectangular main circuit board 1 will be referred to as the Y direction, and the direction perpendicular to the X and Y directions will be referred to as the Z direction. Furthermore, one side in the X direction will be referred to as the X1 direction and the other side as the X2 direction, one side in the Y direction will be referred to as the Y1 direction and the other side as the Y2 direction, the upper side in the cross-sectional view will be referred to as the Z1 direction and the lower side as the Z2 direction. Note that these directions are provided for the convenience of explanation, and the direction along the short side of the rectangular main circuit board 1 may be referred to as the X direction, and the direction along the long side of the rectangular main circuit board 1 may be referred to as the Y direction. Furthermore, these directions are unrelated to the actual installation direction of the power converter 100.

[0027] (Main Circuit Board Configuration) Switching elements 10 are arranged on the main circuit board surface 1a, which is the surface of the main circuit board 1. Here, the switching elements 10 are examples of "semiconductor elements" within the scope of the claims. The switching elements 10 are, for example, power MOSFETs (metal-oxide-semiconductor field-effect transistors), IGBTs (insulated-gate bipolar transistors), RC-IGBTs (reverse-conducting IGBTs), or diodes. The switching elements 10 are surface-mount devices.

[0028] Furthermore, the back surface 1b of the main circuit board, which is the surface opposite to the front surface 1a of the main circuit board, is insulated by the application of a resist material.

[0029] As shown in Figure 1, a plurality of switching elements 10 are arranged on the surface 1a of the main circuit board. Here, the plurality of switching elements 10 are arranged in a line in the X direction. Furthermore, the plurality of switching elements 10 arranged in the X direction are arranged in two rows: a row provided on the Y1 side and a row provided on the Y2 side.

[0030] (Cooler Configuration) As shown in Figure 2, the cooler 2 is positioned on the main circuit board surface 1a side so as to face the switching element 10. The surface of the cooler 2 is in contact with the surface of the switching element 10. Alternatively, the surface of the cooler 2 and the switching element 10 may be in contact via a thermal conductive material with high thermal conductivity, such as thermal grease. With the switching element 10 facing towards the cooler 2 (Z2 direction), the outer edge portion of the main circuit board 1 is fastened and fixed to the surface of the cooler 2 by screws 61. A spacer 62 is positioned between the cooler 2 and the fixing plate 4. The spacer 62 has a female threaded portion on the upper side (Z1 direction side) of the hexagonal prism and a male threaded portion on the lower side (Z2 direction side) of the hexagonal prism with an outer diameter smaller than the length of the diagonal of the hexagon of the hexagonal prism. The cooler 2 is fastened and fixed to the housing 5 by the male threaded portion of the spacer 62.

[0031] As shown in Figure 2, a flow path 2a is provided inside the cooler 2, through which fluid flows by a pump (not shown) located outside the housing 5. The cooler 2 is configured to dissipate the heat generated from the switching element 10 by the fluid flowing through the flow path 2a.

[0032] (Configuration of the control board) The control board 3 is located on the back side 1b of the main circuit board and is configured to control the switching element 10. The control board 3 is also connected to the main circuit board 1 by wiring (not shown) and is configured to control the switching operation of the switching element 10. As the switching element 10 is controlled by the control board 3, the power converter 100 functions as, for example, a power converter having the function of converting DC voltage to AC voltage, such as an inverter; a power converter having the function of converting AC voltage to DC voltage, such as a converter; a power converter having the function of converting DC voltage to other DC voltages or DC voltages with other potentials, such as a chopper circuit and an isolated DC-DC converter; or a power converter having the function of converting AC voltage to other AC voltages, such as a matrix converter. For example, the control board 3 is a microcontroller control board that includes a CPU (Central Processing Unit) as a processor, ROM (Read Only Memory), RAM (Random Access Memory), etc., and is capable of controlling the switching operation of the switching element 10.

[0033] Since the heat generated from the control board 3 is less than the heat generated from the switching element 10, which uses high voltage and high current, the control board 3 is configured to be cooled by the surrounding air.

[0034] (Configuration of the fixing plate for the control board) As shown in Figures 1 and 2, the leaf spring 41 integrally provided on the fixing plate 4 is configured to press the switching element 10 toward the cooler 2 from the back surface 1b side of the main circuit board. Here, the fixing plate 4 is an example of the "control board fixing part" in the claims. The leaf spring 41 is an example of the "pressing part" in the claims. The leaf spring 41 constitutes the "semiconductor element pressing mechanism" in the claims.

[0035] (Arrangement of fixing plate) As shown in Figures 1 and 2, the fixing plate 4 is positioned between the main circuit board 1 and the control board 3, which is between the cooler 2 and the control board 3. Here, the fixing plate 4 is fastened and fixed by screws 63 using the female threaded portion of the spacer 62 used to fix the cooler 2 to the housing 5.

[0036] (Fixing the control board with a fixing plate) As shown in Figure 1, the fixing plate 4 has a frame portion 42. The frame portion 42 is rectangular in shape, and a plurality of control board fixing bosses 43 protruding in the Z1 direction are provided on the frame portion 42. The rectangular frame portion 42 is composed of two long sides along the X direction and two short sides along the Y direction. Also, as shown in Figure 1, the fixing plate 4 has an opening 40. Therefore, when connecting the main circuit board 1 and the control board 3 by wiring, it is possible to connect the main circuit board 1 and the control board 3 through the opening in the fixing plate 4, thereby suppressing the length of the wiring. As a result, it is possible to suppress the generation of noise in the control signal between the main circuit board 1 and the control board 3.

[0037] The control board 3 is fixed to the fixing plate 4 by a control board fixing boss 43, which is provided on the surface of the fixing plate 4 on the side facing the control board 3 and protrudes toward the control board 3 (in the Z1 direction), and by screws (not shown). Specifically, the control board 3 is fixed to the fixing plate 4 by fastening two sides of the outer edge of the rectangular control board 3 that are opposite in the Y direction (two long sides along the X direction) using the control board fixing boss 43, which is arranged along the two sides opposite in the Y direction, and fastening members (not shown). The fixing plate 4 is formed of sheet metal, for example, and the control board fixing boss 43 is welded to the surface of the fixing plate 4 on the side facing the control board 3.

[0038] (Arrangement of leaf springs) As shown in Figures 1 and 2, the fixing plate 4 has multiple leaf springs 41 that are elastically deformable (flexible) and press the switching element 10 toward the cooler 2 from the back surface 1b of the main circuit board 1, inside the multiple control board fixing bosses 43 when viewed from the thickness direction (Z direction) of the main circuit board 1. Specifically, the leaf springs 41 are formed integrally with the fixing plate 4 by cutting out a sheet of metal and bending it toward the main circuit board 1 side (Z2 direction). The leaf springs 41 also have a curved portion 41a which is convex on the back surface 1b side of the main circuit board. This curved portion 41a is configured to press the back surface 1b of the main circuit board toward the cooler 2 by contacting the back surface 1b of the main circuit board.

[0039] Furthermore, as shown in Figures 1 and 2, the leaf spring 41 is configured to press the portion of the back surface 1b of the main circuit board 1 that overlaps with the portion where the switching element 10 is located, when viewed from the thickness direction (Z direction) of the main circuit board 1, from the back surface 1b of the main circuit board 1b towards the cooler 2. Specifically, when the leaf spring 41 is elastically deformed, the biasing force due to the elastic deformation presses the portion of the back surface 1b of the main circuit board 1b that overlaps with the center of the switching element 10 in the Y direction when viewed from the thickness direction (Z direction) of the main circuit board 1, from the back surface 1b of the main circuit board 1b towards the cooler 2.

[0040] Furthermore, as shown in Figures 1 and 2, the leaf spring 41 provided on the Y1 side protrudes in the Y2 direction, and the leaf spring 41 provided on the Y2 side protrudes in the Y1 direction. In other words, the leaf springs 41 protrude inward from the frame portion 42. Specifically, the leaf springs 41 are provided in pairs, with one leaf spring 41 protruding in the Y1 direction and the other protruding in the Y2 direction facing each other, and multiple pairs of leaf springs 41 are provided.

[0041] Furthermore, as shown in Figures 1 and 2, the leaf spring 41 is integrally provided with the fixing plate 4 so as to protrude from the fixing plate 4 toward the main circuit board 1. Specifically, the leaf spring 41 is provided so as to protrude downward (in the Z2 direction) from the fixing plate 4 which is located above (in the Z1 direction) the main circuit board 1. Also, the tip of the curved portion 41a of the leaf spring 41 faces upward (in the Z1 direction).

[0042] Further, as shown in FIG. 1, the plurality of switching elements 10 are arranged side by side in the X direction, and the plurality of leaf springs 41 are also arranged along the X direction. Further, the plurality of leaf springs 41 are provided along the direction in which the plurality of switching elements are arranged side by side. For this reason, due to the biasing force caused by the elastic deformation (bending deformation) of the plurality of leaf springs 41, the plurality of leaf springs 41 press the plurality of switching elements 10 from the back surface 1b side of the main circuit board toward the cooler 2 along the direction in which the plurality of switching elements 10 are arranged side by side. Specifically, one leaf spring 41 presses the plurality of switching elements 10. Further, leaf springs 41 having the same shape are arranged along the X direction and linearly press the switching elements 10 arranged side by side in the X direction. Further, the switching elements 10 are arranged in two rows along the X direction and are symmetrically pressed by a pair of leaf springs 41 having a symmetric shape when viewed from the X direction.

[0043] (Effects of the First Embodiment) In the first embodiment, the following effects can be obtained.

[0044] In the power conversion device 100 according to the first embodiment, as described above, the main circuit board 1 having the main circuit board surface 1a on which the switching elements 10 are arranged and the main circuit board back surface 1b which is the surface opposite to the main circuit board surface 1a, the cooler 2 arranged on the main circuit board surface 1a side so as to face the switching elements 10 and radiating the heat generated from the switching elements 10, and the leaf spring 41 pressing the switching elements 10 from the main circuit board back surface 1b side toward the cooler 2 side are provided. Thereby, since the switching elements 10 are pressed toward the cooler 2 side by the leaf spring 41, even when there is warping or bending in the main circuit board 1, it is possible to suppress the contact between the surface of the cooler 2 and the surface of the switching elements 10 from becoming insufficient. As a result, even when the main circuit board 1 is warped or bent, it is possible to suppress a decrease in the heat radiation performance of the heat generated from the switching elements 10 by the cooler 2.

[0045] Furthermore, in the power conversion device 100 according to the first embodiment, as described above, the leaf spring 41 is configured to press from the back surface 1b of the main circuit board 1, on the part of the back surface 1b of the main circuit board 1 that overlaps with the part where the switching element 10 is arranged, when viewed from the thickness direction of the main circuit board 1. As a result, when viewed from the thickness direction (Z direction) of the main circuit board 1, the part of the back surface 1b of the main circuit board 1 that overlaps with the part where the switching element 10 is arranged can be pressed, so that even if there is warping or bending in the main circuit board 1, the switching element 10 can be made to contact the cooling part more reliably.

[0046] Furthermore, in the power conversion device 100 according to the first embodiment, as described above, the pressing part is a leaf spring. Here, in order to properly press the switching element 10 from the back surface 1b side of the main circuit board to the cooler 2 side using a pressing part made of a rigid body, it is necessary to manufacture the pressing part with high precision. However, if the pressing part is a leaf spring 41, the switching element 10 is pressed to the cooler 2 side by the deformation of the leaf spring 41, so the manufacturing of a pressing part using a leaf spring 41 does not require the same level of precision as when using a pressing part made of a rigid body. As a result, by using a leaf spring 41 for the pressing part, the switching element 10 can be pressed to the cooler 2 side more easily.

[0047] Furthermore, the power conversion device 100 according to the first embodiment further includes a control board 3 that controls the switching elements 10 arranged on the back surface 1b side of the main circuit board, and a fixing plate 4 which is a control board fixing part that is arranged between the cooler 2 and the control board 3 and fixes the control board 3, and the leaf spring 41 which is a pressing part is provided on the fixing plate 4. As a result, the control board 3 can be fixed by the fixing plate 4 on which the leaf spring 41 is provided, so the power conversion device 100 can be made more space-saving compared to the case where the leaf spring 41 and the fixing plate 4 are provided in separate locations.

[0048] Also, in the power conversion device 100 according to the first embodiment, as described above, a plurality of control board fixing bosses 43 that protrude toward the control board 3 side and fix the control board 3 are provided. The leaf spring 41 is provided inside the plurality of control board fixing bosses 43 when viewed from the thickness direction (Z direction) of the main circuit board 1. Thereby, the control board 3 can be separated from the mounting surface of the fixing plate 4 to which the control board 3 is attached by the control board fixing bosses 43. As a result, an air flow path can be secured between the control board 3 and the mounting surface, so that the control board 3 can be efficiently cooled. Further, since the main circuit board 1 and the control board 3 are separated, insulation between the main circuit board 1 and the control board 3 can be ensured. Furthermore, since the leaf spring 41 is provided inside the plurality of control board fixing bosses 43 when viewed from the thickness direction (Z direction) of the main circuit board 1, an increase in the size of the power conversion device 100 can be suppressed.

[0049] Also, in the power conversion device 100 according to the first embodiment, as described above, the control board fixing portion includes the fixing plate 4 provided with the control board fixing bosses 43, and the leaf spring 41 is provided integrally with the fixing plate 4. Therefore, since the control board 3 can be fixed on the fixing plate 4 provided with the control board fixing bosses 43, the control board 3 can be fixed while being reinforced by the fixing plate 4. Further, since the leaf spring 41 is provided integrally with the fixing plate 4, an increase in the number of parts of the power conversion device 100 can be suppressed, and complication of the structure of the power conversion device 100 can be suppressed.

[0050] Also, in the power conversion device 100 according to the first embodiment, as described above, the fixing plate 4 has a frame portion 42, and the leaf spring 41 protrudes inside the frame portion 42 and is provided integrally with the fixing plate 4 so as to protrude from the fixing plate 4 toward the main circuit board 1 side. Therefore, since the leaf spring 41 is provided so as to protrude toward the main circuit board 1 side, even if the leaf spring 41 is provided integrally with the fixing plate 4, the switching element 10 can be surely pressed toward the cooler 2 side by the leaf spring 41.

[0051] Furthermore, in the power conversion device 100 according to the first embodiment, as described above, the main circuit board surface 1a has a plurality of switching elements 10 arranged on it, and the plurality of switching elements 10 are arranged side by side. The leaf spring 41 is configured to press the plurality of switching elements 10 toward the cooler 2 from the back surface 1b of the main circuit board along the direction in which the plurality of switching elements 10 are arranged side by side. As a result, the plurality of switching elements 10 can be pressed toward the cooler 2 from the back surface 1b of the main circuit board along the direction in which the plurality of switching elements 10 are arranged side by side, so that the surfaces of the plurality of switching elements 10 can be brought into contact with the surface of the cooler 2. As a result, the decrease in the heat dissipation performance of the heat generated from the plurality of switching elements 10 by the cooler 2 can be suppressed.

[0052] [Second Embodiment] Next, a power converter 200 according to a second embodiment will be described with reference to Figures 3 and 4. The configuration of the power converter 200 according to this second embodiment is the same as that of the power converter 100 of the first embodiment shown in Figures 1 and 2, except that it has a connecting portion 244 that connects two opposing sides of the frame portion 242, and a boss 243b for fixing the control board inside the frame is provided on the connecting portion 244. In Figure 3, for the sake of explanation, the control board 3 and the housing 5 are omitted from the drawing. Figure 4 is a cross-sectional view taken along the line IV-IV shown in Figure 3.

[0053] (Configuration of the power converter) As shown in Figures 3 and 4, in the power converter 200 according to the second embodiment, the fixing plate 204 has a frame portion 242, and the control board fixing boss 243 includes a frame-top control board fixing boss 243a that fixes the control board 3 on the surface of the frame portion 242. The frame portion 242 also has three openings 240 (see Figure 3). The fixing plate 204 is arranged inside the frame portion 242 and includes a frame-inside control board fixing boss 243b that protrudes toward the control board 3 and fixes the control board 3. The leaf springs 241 are provided inside the frame portion 242. Specifically, a plurality of elastically deformable (flexible) leaf springs 241 that press the switching element 10 toward the cooler 2 from the back surface 1b of the main circuit board are provided integrally with the fixing plate 204. Furthermore, the sheet metal is notched and bent toward the main circuit board 1 side (Z2 direction), thereby integrally forming the leaf spring 241 with the fixing plate 204. The leaf spring 241 also has a curved portion 241a that is convex on the back surface 1b side of the main circuit board. This curved portion 241a contacts the back surface 1b of the main circuit board, thereby pressing the back surface 1b of the main circuit board toward the cooler 2 side. Here, the fixing plate 204 is an example of the "control board fixing portion" in the claims, and the leaf spring 241 is an example of the "pressing portion" in the claims.

[0054] Furthermore, as shown in Figures 3 and 4, the frame portion 242 has a connecting portion 244 that connects two opposing sides of the frame portion 242, and the boss 243b for fixing the control board inside the frame is provided on the connecting portion 244. In other words, the connecting portion 244 is provided to connect two opposing sides of the opening 240. Specifically, the connecting portion 244 is provided between the leaf springs 241 in the X direction. Also, the connecting portion 244 is provided along the XY plane. Furthermore, the boss 243b for fixing the control board inside the frame is provided in the center of the two opposing sides of the frame portion 242. In other words, the boss 243b for fixing the control board inside the frame is provided in the center of the connecting portion 244. Furthermore, the boss 243b for fixing the control board inside the frame is provided so that its height in the Z direction is equal to that of the boss 243a for fixing the control board on top of the frame.

[0055] (Effects of the second embodiment) In the second embodiment, the following effects can be obtained.

[0056] In the power conversion device 200 according to the second embodiment, as described above, the fixing plate 204, which is the control board fixing part, has a frame portion 242, and the control board fixing boss 243 further includes a frame-top control board fixing boss 243a that fixes the control board 3 on the surface of the frame portion 242, and the fixing plate 204 is arranged inside the frame portion 242, protruding toward the control board 3 side and including an in-frame control board fixing boss 243b that fixes the control board 3, and the leaf spring 241 is provided inside the frame portion 242. As a result, the control board 3 can be fixed by the frame-top control board fixing boss 243a provided on the surface of the frame portion 242 of the fixing plate 204, as well as the in-frame control board fixing boss 243b provided inside the frame portion 242. Therefore, the number of fixing points of the control board 3 on the fixing plate 204 can be increased, and the fixing strength of the control board 3 to the fixing plate 204 can be improved.

[0057] Furthermore, in the power conversion device 200 according to the second embodiment, as described above, the frame portion 242 has a connecting portion 244 that connects two opposing sides of the frame portion 242, and the boss 243b for fixing the control board inside the frame is provided on the connecting portion 244. Therefore, the strength of the fixing plate 204 can be improved by the connecting portion 244 that connects two opposing sides of the frame portion 242. In addition, by providing the boss 243b for fixing the control board inside the frame on the connecting portion 244, the number of fixing points of the control board 3 on the fixing plate 204 can be increased, thereby improving the fixing strength of the control board 3 to the fixing plate 204.

[0058] [Third Embodiment] Next, a power converter 300 according to a third embodiment will be described with reference to Figures 5 and 6. The configuration of the power converter 300 according to this third embodiment is the same as that of the power converter 100 of the first embodiment shown in Figures 1 and 2, except that the leaf spring 341 is integrally provided on the fixing plate 304 so as to connect two opposing sides of the frame portion 342 of the fixing plate 304. In Figure 6, for the sake of explanation, the control board 3 and the housing 5 are omitted from the diagram. Also, Figure 6 is a cross-sectional view taken along the line VI-VI shown in Figure 5.

[0059] (Configuration of the power converter) As shown in Figures 5 and 6, in the power converter 300 according to the third embodiment, the leaf spring 341 is provided so as to connect two opposing sides of the frame portion 342 of the fixed plate 304. The frame portion 342 also has an opening 340 (see Figure 5). The leaf spring 341 is also integrally provided with the fixed plate 304. Specifically, the elastically deformable (bending) leaf spring 341 is configured to press two locations on the main circuit board 1 by the biasing force due to the elastic deformation (bending) of the leaf spring 341 when viewed from the X direction. For this reason, a plurality of leaf springs 341 of the same shape arranged in the X direction are configured to press two rows of switching elements 10 along the X direction. The leaf spring 341 also has two curved portions 341a on the back surface 1b side of the main circuit board which are convex. The curved portion 341a contacts the back surface 1b of the main circuit board, thereby pressing the back surface 1b of the main circuit board toward the cooler 2. The shape of the leaf spring 341 is such that, when viewed from the X direction, the two points that press against the main circuit board 1 are connected in an upward convex shape. The leaf spring 341 also has a flat portion 341b that is flat near the center of the two points that press against the main circuit board 1 when viewed from the X direction, and in the Z direction, the height of the flat portion 341b of the leaf spring 341 is lower than the height at which the fixing plate 304 is positioned.

[0060] (Effects of the third embodiment) In the third embodiment, the following effects can be obtained.

[0061] In the power converter 300 according to the third embodiment, the pressing part, the leaf spring 341, is integrally provided on the fixing plate 304 so as to connect two opposing sides of the frame portion 342 of the fixing plate 304. As a result, the two opposing sides of the frame portion 342 are integrally connected by the pressing part, the mechanical strength of the fixing plate 304 can be improved.

[0062] [Fourth Embodiment] Next, a power converter 400 according to the fourth embodiment will be described with reference to Figures 7 and 8. The configuration of the power converter 400 according to this fourth embodiment is the same as the power converter 300 of the third embodiment shown in Figures 5 and 6, except that a boss 443b for fixing the control board inside the frame is provided on the surface of the leaf spring 441 on the control board 3 side, which is integrally provided on the fixing plate 404 so as to connect two opposing sides of the frame portion 442 of the fixing plate 404. Note that in Figure 7, the control board 3 and housing 5 are omitted from the description for the sake of clarity. Figure 8 is a cross-sectional view taken along the line VIII-VIII shown in Figure 7.

[0063] (Configuration of the power converter) As shown in Figures 7 and 8, in the power converter 400 according to the fourth embodiment, the leaf spring 441 is integrally provided on the fixing plate 404 so as to connect two opposing sides of the frame portion 442 of the fixing plate 404. The frame portion 442 also has an opening 440 (see Figure 7). The boss 443b for fixing the control board inside the frame is provided on the surface of the leaf spring 441 on the side facing the control board 3. Specifically, the elastically deformable (bending) leaf spring 441 is configured to press two locations on the main circuit board 1 by the biasing force due to the elastic deformation (bending) of the leaf spring 441 when viewed from the X direction. For this reason, a plurality of leaf springs 441 of the same shape arranged in the X direction are configured to press two rows of switching elements 10 along the X direction. The leaf spring 441 also has two curved portions 341a on the back surface 1b side of the main circuit board which are convex. The curved portion 441a contacts the back surface 1b of the main circuit board, thereby pressing the back surface 1b of the main circuit board toward the cooler 2. The shape of the leaf spring 441 is such that, when viewed from the X direction, the two points that press against the main circuit board 1 are connected in an upward convex shape. The leaf spring 441 also has a flat portion 441b that is flat near the center of the two points that press against the main circuit board 1 when viewed from the X direction, and in the Z direction, the height of the flat portion 441b of the leaf spring 441 is lower than the height at which the fixing plate 304 is positioned. Furthermore, a boss 443b for fixing the control board within the frame is provided on the surface of the flat portion 441b on the control board 3 side, which is midway between two opposing sides of the frame portion 442 in the Y direction. The bosses 443b for fixing the control board within the frame, provided on the flat portions 441b of the multiple leaf springs 441, are arranged at equal intervals along the X direction. Furthermore, the boss 443b for fixing the control board inside the frame is provided so that its height in the Z direction is equal to that of the boss 443a for fixing the control board above the frame.

[0064] (Effects of the fourth embodiment) In the fourth embodiment, the following effects can be obtained.

[0065] In the power conversion device 400 according to the fourth embodiment, the boss 443b for fixing the control board within the frame is provided on the surface of the leaf spring 441, which is the pressing part, on the control board 3 side. As a result, it is not necessary to provide the leaf spring 441, which is the pressing part, and the boss 443b for fixing the control board within the frame in different locations, thus enabling space saving for the power conversion device 400.

[0066] Furthermore, in the power conversion device 400 according to the fourth embodiment, as described above, a boss 443b for fixing the control board inside the frame is provided on the surface of the flat portion 441b on the control board 3 side, which is the midpoint between two opposing sides of the frame portion 442 in the Y direction. As a result, the control board 3 can be fixed by the boss 443a for fixing the control board on top of the frame portion 442 provided on the surface of the fixing plate 404, as well as the boss 443b for fixing the control board inside the frame portion 442 provided on the inside of the frame portion 442. Therefore, the number of fixing points of the control board 3 on the fixing plate 404 can be increased, and the fixing strength of the control board 3 to the fixing plate 404 can be improved.

[0067] [Fifth Embodiment] Next, a power converter 500 according to the fifth embodiment will be described with reference to Figures 9 and 10. The configuration of the power converter 500 according to this fifth embodiment is the same as the power converter 100 of the first embodiment shown in Figures 1 and 2, except that the fixing plate 504 for fixing the control board 3 is fixed to the housing 5 by being fastened together with the cooler 2 without using a spacer 62, and the fixing plate 504 fixed to the Y1 side and the fixing plate 504 fixed to the Y2 side are formed separately. Note that in Figure 9, the control board 3 and housing 5 are omitted from the diagram for the sake of clarity. Figure 10 is a cross-sectional view taken along the line X-X shown in Figure 9.

[0068] (Configuration of the power converter) As shown in Figures 9 and 10, in the power converter 500 according to the fifth embodiment, the fixing plate 504 that fixes the control board 3 is fixed to the housing 5 by fastening it together with the cooler 2 using screws 61. That is, the fixing plate 504 is positioned between the cooler 2 and the control board 3. The control board 3 is fastened and fixed onto the fixing plate 504 by a control board fixing boss 543, which protrudes toward the control board 3 and is provided on the surface of the fixing plate 504 on the control board 3 side, and a fastening member (not shown). The control board fixing boss 543 is provided on the surface of the fixing plate 504 by welding, but instead of the control board fixing boss 543, a through hole may be provided in the fixing plate 504 and the cooler 2 and the fixing plate 504 may be fastened and fixed to the housing 5 by fastening them together with a spacer 62.

[0069] Furthermore, as shown in Figures 9 and 10, the leaf spring 541 is configured to be elastically deformable (flexible) so as to press the switching element 10 toward the cooler 2 from the back surface 1b side of the main circuit board. The leaf spring 541 is also integrally provided with the fixing plate 504, and is configured to press from the back surface 1b side of the main circuit board 1, on the portion of the back surface 1b of the main circuit board 1 that overlaps with the portion where the switching element 10 is located, when viewed from the thickness direction (Z direction) of the main circuit board 1. Specifically, the two fixing plates 504 have a rectangular shape extending along the X direction and are fixed to the housing 5 by being fastened together with the cooler 2 by screws 61 along the X direction. In addition, in the Y direction, a total of two fixing plates 504 are arranged on the outside of the main circuit board 1, one on each side. The fixing plate 504 positioned on the Y1 side has a plurality of leaf springs 541 integrally formed thereon that extend upward (in the Z1 direction) and then protrude downward (in the Z2 direction) from the control board 3 side to press against the back surface 1b of the main circuit board.

[0070] Furthermore, as shown in Figures 9 and 10, the leaf spring 541 has a flat surface portion 541a that contacts the back surface 1b of the main circuit board. Therefore, the contact surface between the leaf spring 541 and the back surface 1b of the main circuit board is configured to be flat, and the pressing surface along the X direction is configured to press the switching element 10 toward the cooler 2. Also, as shown in Figure 10, the leaf spring 541 presses toward the cooler 2 from the back surface 1b of the main circuit board 1b by the flat surface portion 541a that covers the portion of the back surface 1b of the main circuit board 1 that overlaps with the surface on which the switching element 10 is located when viewed from the thickness direction (Z direction) of the main circuit board 1. Other effects of pressing the switching element 10 by the leaf spring 541 are the same as the effects when the switching element 10 is pressed by the leaf spring 41 in the power converter 100 of the first embodiment.

[0071] (Effects of the Fifth Embodiment) In the fifth embodiment, the following effects can be obtained.

[0072] In the power converter 500 according to the fifth embodiment, the fixing plate 504 that secures the control board 3 is configured to be fastened together with the cooler 2. This makes it possible to suppress an increase in the number of components of the power converter 500.

[0073] Furthermore, in the power conversion device 500 according to the fifth embodiment, the control board 3 protrudes toward the control board 3 side and is fastened and fixed onto the fixing plate 504 by a control board fixing boss 543 provided on the surface of the fixing plate 504 toward the control board 3 side and a fastening member (not shown). In the first to fourth embodiments, the fixing plates 4, 204, 304, and 404 are fixed via spacers 62, and the control board 3 is further fixed to the fixing plates 4, 204, 304, and 404 by control board fixing bosses 43, 243, and 443 provided on top of them. In contrast, in the power conversion device 500 of the fifth embodiment, the fixing plate 504 is fixed without spacers 62, so the size of the power conversion device 500 in the Z direction can be suppressed.

[0074] Furthermore, in the power conversion device 500 according to the fifth embodiment, the leaf spring 541 is pressed from the back surface 1b of the main circuit board 1 towards the cooler 2 by a flat surface portion 541a that covers the portion of the back surface 1b of the main circuit board 1 that overlaps with the surface on which the switching element 10 is arranged, when viewed from the thickness direction (Z direction) of the main circuit board 1. Because the main circuit board 1 is pressed by a flat surface, the pressing force is distributed. As a result, it is possible to suppress excessive pressing force being applied to the main circuit board 1 and the switching element 10.

[0075] [Modifications] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than the description of the embodiments above, and further includes all modifications (modifications) within the meaning and scope equivalent to the claims.

[0076] In the first to fifth embodiments described above, an example was shown in which a leaf spring presses from the back surface 1b of the main circuit board 1 to the portion of the back surface 1b of the main circuit board 1 that overlaps with the portion of the switching element 10 that is arranged, as viewed from the thickness direction (Z direction) of the main circuit board 1. However, the present invention is not limited thereto. As long as insufficient contact between the surface of the cooler 2 and the surface of the switching element 10 can be suppressed, the area near the portion of the back surface 1b of the main circuit board 1 that overlaps with switching element 10 that is arranged may be pressed from the back surface 1b of the main circuit board 1.

[0077] Furthermore, although the first to fifth embodiments described above show an example in which the pressing part is a leaf spring, the present invention is not limited thereto. For example, a pressing part made of a rigid body such as a block may be used. Specifically, as in the power converter 1000 in the first modified example of the first embodiment shown in Figures 11 and 12, the fixed plate 1004 may be provided with a pressing part 1041 which is a block. The pressing part 1041 which is a block is provided along two sides of the opening 1040 of the fixed plate 1004 that extend in the X direction.

[0078] Furthermore, as shown in Figures 13 and 14, in the power converter 2000 in the second modified example of the first embodiment, a sheet metal may be cut out and bent toward the control board 3 side (Z1 direction) to form a non-leaf spring pressing portion 2041 on the fixing plate 2004. The pressing portion 2041 is provided along two sides of the opening 2040 of the fixing plate 2004 that extend in the X direction, and has a flat surface portion 2041a that contacts the back surface 1b of the main circuit board.

[0079] Furthermore, although the first to fifth embodiments described above show examples in which the pressing portion is provided on the control board fixing portion, the present invention is not limited thereto. The pressing portion may be provided separately from the control board fixing portion as long as the switching element 10 can be pressed toward the cooler 2.

[0080] Furthermore, while the first to fourth embodiments described above show examples in which the control board is mounted on a fixing plate with bosses 43 for fixing the control board, the present invention is not limited thereto. For example, the control board may be directly fastened and fixed to the fixing plate without providing bosses 43 for fixing the control board.

[0081] Furthermore, although the first to fourth embodiments described above show examples in which the leaf spring is integrally provided with the fixing plate, the present invention is not limited thereto. For example, as in the power converter 3000 in the third modified example of the first embodiment shown in Figures 15 and 16, the leaf spring 3041 as a pressing part may be provided as a separate part of the fixing plate 3004 having an opening 1040. The leaf spring 3041 has a curved portion 3041a that contacts the back surface 1b of the main circuit board and has a convex shape on the side facing the back surface 1b of the main circuit board. The leaf spring 3041 provided as a separate part is fastened and fixed to two sides of the opening 3040 of the fixing plate 3004 along the X direction by screws 64.

[0082] Furthermore, as in the power converter 1200 in the modified example of the second embodiment shown in Figure 17, the fixing plate 1204 has a connecting portion 1244 integrally provided, while a leaf spring 1241 as a pressing portion may be provided as a separate part of the fixing plate 1204 having three openings 1240. A boss 1243a for fixing the control board on the frame portion 1242 is provided on the surface of the frame portion 1242 on the control board 3 side, and a boss 1243b for fixing the control board inside the frame is provided on the surface of the connecting portion 12444 on the control board 3 side. The leaf spring 1241 also has a curved portion 1241a that contacts the back surface 1b of the main circuit board, with the back surface 1b side of the main circuit board being convex. The leaf spring 1241 provided as a separate part is fastened and fixed to two sides of the three openings 1240 of the fixing plate 1204 along the X direction by screws 64.

[0083] Furthermore, as in the power converter 1300 in the modified example of the third embodiment shown in Figure 18, a leaf spring 1341 as a pressing part may be provided on the fixing plate 1304 as a separate component of the fixing plate 1304 having an opening 1340. The leaf spring 1341 has two curved portions 1341a that contact and press against the back surface 1b of the main circuit board, with the side facing the back surface 1b of the main circuit board being convex. The shape of the leaf spring 1341 is such that, when viewed from the X direction, the two points that press against the main circuit board 1 are integrally connected so as to be convex upwards. The leaf spring 1341 also has a flat portion 1341b near the center of the two points that press against the main circuit board 1 when viewed from the X direction. The leaf spring 1341 provided as a separate component is fastened and fixed to the two sides of the opening 1340 of the fixing plate 1304 along the X direction by screws 64.

[0084] Furthermore, as in the power converter 1400 in the modified example of the fourth embodiment shown in Figure 19, a leaf spring 1441 as a pressing part may be provided on the fixing plate 1404 as a separate part of the fixing plate 1404 having an opening 1440. The leaf spring 1441 has two curved portions 1441a that contact and press against the back surface 1b of the main circuit board, with the side facing the back surface 1b of the main circuit board being convex. The shape of the leaf spring 1441 is such that, when viewed from the X direction, the two points that press against the main circuit board 1 are integrally connected so as to be convex upwards. The leaf spring 1441 also has a flat portion 1441b near the center of the two points that press against the main circuit board 1 when viewed from the X direction, and a boss 1443b for fixing the control board within the frame is provided on the surface of the flat portion 1441b. Furthermore, the leaf spring 1341, which is provided as a separate component, is fastened and fixed to two sides of the opening 1340 of the fixing plate 1304 along the X direction by screws 64.

[0085] Furthermore, while the third and fourth embodiments described above show examples in which the leaf spring 441 as a pressing part is provided on the fixing plate so as to connect two opposing sides of the frame portion of the fixing plate, the present invention is not limited thereto. The leaf spring 441 as a pressing part may be provided so as to connect two adjacent sides of the frame portion 442.

[0086] Furthermore, in the second embodiment described above, an example was shown in which the connecting portion 244 is provided on the fixing plate 204 so as to connect two opposing sides of the frame portion 242 of the fixing plate 204, but the present invention is not limited to this. For example, the connecting portion 244 may be provided so as to connect two adjacent sides of the frame portion 242.

[0087] Furthermore, as shown in Figures 20 and 21, in the fourth modified example of the first embodiment, the connecting portion 4044 may be provided as a separate part of the fixing plate 4 having the opening 40. Specifically, the connecting portion 4044 provided as a separate part is fastened and fixed onto the frame portion 42 by screws 64 so as to connect two opposing sides of the frame portion 42 of the fixing plate 4. The connecting portion 4044 is also provided with a boss 4043 for fixing the control board inside the frame. When the connecting portion 4044 is fastened and fixed onto the frame portion 42 by screws 64, the boss 4043 for fixing the control board inside the frame protrudes toward the control board 3 side (Z1 direction) and is fastened and fixed so as to be positioned in the center of the two opposing sides of the frame portion 4042.

[0088] Furthermore, while the first to fifth embodiments described above show examples in which the switching element 10 is arranged on the surface layer of the surface 1a of the main circuit board 1, the present invention is not limited thereto. As shown in Figures 22 and 23, in the fifth modification of the first embodiment, the switching element 5010 may be embedded in the main circuit board 5001, on the side where the cooler 2 is arranged. Also, in the fifth modification of the first embodiment, since the switching element 5010 is embedded in the main circuit board 5001, the switching element 5010 may be replaced from a surface mount device to a semiconductor chip. When the switching element 5010 is replaced with a semiconductor chip, the main circuit board 5001 may be used to ensure insulation between the switching element 5010 and the cooler 2.

[0089] Furthermore, while the first to fifth embodiments described above show an example in which the switching elements 10 are arranged in two rows on the main circuit board 1, the present invention is not limited thereto. The switching elements 10 may be arranged in one row on the main circuit board 1, or in three or more rows.

[0090] Furthermore, in the first to fifth embodiments described above, a flow path 2a is provided inside the cooler 2 so that fluid flows through it using a pump (not shown) located outside the housing 5, and the cooler 2 is configured to dissipate the heat generated from the switching element 10 using the fluid flowing through the flow path 2a. However, the present invention is not limited to this. For example, the configuration for dissipating the heat generated from the switching element 10 may be a heat dissipation fin.

[0091] Furthermore, while the third and fourth embodiments described above show examples where the height of the flat portions 341b and 441b in the Z direction is lower than the height at which the fixing plates 304 and 404 are positioned, the present invention is not limited thereto. The height of the flat portions 341b and 441b in the Z direction may be the same as the height at which the fixing plates 304 and 404 are positioned, or the height of the flat portions 341b and 441b in the Z direction may be higher than the height at which the fixing plates 304 and 404 are positioned, as long as it is at a lower position than the height at which the control board 3 is positioned.

[0092] 1. 5001 Main circuit board 10. 5010 Switching element 2 Cooler (cooling section) 3 Control board 4. 204, 304, 404, 504, 1004, 1204, 1304, 1404, 2004, 3004 Fixing plate (control board fixing section) 41, 241, 341, 441, 541, 1241, 1341, 1441 Leaf spring (pressing section) 42, 242, 342, 442, 542, 1042, 1242, 1342, 1442, 2042, 3042 Frame section 1041, 2041 Pressing section 43, 243, 343, 443, 543 Boss for fixing control board 243a, 443a, 1243a, 1443a Bosses for fixing the control board on top of the frame 243b, 443b, 1243b, 1443b, 4043 Bosses for fixing the control board inside the frame 244, 1244 Connection part 5 Housing 61, 63, 64 Screw 62 Spacer 100, 200, 300, 400, 500, 1000, 1200, 1300, 1400, 2000, 3000, 4000, 5000 Power converter

Claims

1. A power conversion device comprising: a main circuit board having a main circuit board surface on which semiconductor elements for power conversion are arranged, and a main circuit board back surface which is the surface opposite to the main circuit board surface; a cooling unit disposed on the main circuit board surface side so as to face the semiconductor elements and for dissipating heat generated from the semiconductor elements; and a pressing unit for pressing the semiconductor elements from the main circuit board back surface side toward the cooling unit.

2. The power conversion device according to claim 1, wherein the pressing portion is configured to press from the back surface side of the main circuit board a portion of the back surface of the main circuit board that overlaps with the portion on which the semiconductor element is arranged, when viewed from the thickness direction of the main circuit board.

3. The power conversion device according to claim 1, wherein the pressing portion is a leaf spring.

4. The power conversion device according to claim 1, further comprising: a control board disposed on the back side of the main circuit board for controlling the semiconductor elements; and a control board fixing part disposed between the cooling part and the control board for fixing the control board, wherein the pressing part is provided on the control board fixing part.

5. The power conversion device according to claim 4, wherein the control board fixing portion is provided with a plurality of control board fixing bosses that protrude toward the control board and fix the control board, and the pressing portion is provided inside the plurality of control board fixing bosses when viewed from the thickness direction of the main circuit board.

6. The power conversion device according to claim 5, wherein the control board fixing portion includes a fixing plate provided with bosses for fixing the control board, and the pressing portion is provided integrally with the fixing plate.

7. The power conversion device according to claim 6, wherein the fixing plate has a frame portion, and the pressing portion is provided integrally with the fixing plate such that it protrudes inward from the frame portion and protrudes from the fixing plate toward the main circuit board side.

8. The power conversion device according to claim 7, wherein the pressing portion is integrally provided on the fixing plate so as to connect two opposing sides of the frame portion of the fixing plate.

9. The power conversion device according to claim 6, wherein the fixing plate has a frame portion, the control board fixing boss further includes a frame-mounted control board fixing boss for fixing the control board on the surface of the frame portion, the fixing plate is disposed inside the frame portion and includes an in-frame control board fixing boss that protrudes toward the control board and fixes the control board, and the pressing portion is provided inside the frame portion.

10. The power conversion device according to claim 9, wherein the frame portion has a connecting portion provided to connect two opposing sides of the frame portion, and the boss for fixing the control board inside the frame is provided on the connecting portion.

11. The power conversion device according to claim 9, wherein the boss for fixing the control board within the frame is provided on the surface of the pressing portion on the control board side.

12. The power conversion device according to claim 1, wherein the surface of the main circuit board has a plurality of semiconductor elements arranged thereon, and the plurality of semiconductor elements are arranged side by side, and the pressing portion is configured to press the plurality of semiconductor elements toward the cooling portion from the back side of the main circuit board along the direction in which the plurality of semiconductor elements are arranged side by side.

13. A semiconductor element pressing mechanism comprising a main circuit board having a main circuit board surface on which power-converting semiconductor elements are arranged, and a main circuit board back surface which is the surface opposite to the main circuit board surface, wherein the semiconductor elements arranged on the main circuit board are positioned on the main circuit board side from the back surface side of the main circuit board so as to face the semiconductor elements, and the mechanism includes a pressing part that presses the semiconductor elements toward a cooling part that dissipates heat generated from the semiconductor elements.

Images