Power conversion device

Abstract

A power conversion device (100) comprises: a power conversion circuit body (3) that converts a DC current into an AC current; a smoothing capacitor (2) which has a capacitor element (not illustrated) accommodated in a capacitor case (20) and which is electrically connected to the power conversion circuit body; an enclosure (4), which has a bottom part (41) and a sidewall (40) erected around the bottom part, and in which the power conversion circuit body and the smoothing capacitor are housed; a DC power supply terminal (1) which is provided in the sidewall and to which a DC current is supplied; and a busbar (5C) having a positive electrode conductor and a negative electrode conductor (5), with one end connected to the DC power supply terminal and the other end connected to DC input terminals (32U, V, W, 33U, V, W) of the power conversion circuit body. The smoothing capacitor is disposed between the DC power supply terminal and the power conversion circuit body, and the busbar is connected to the power conversion circuit body by going through a space between the smoothing capacitor and the bottom part.

Description

Power Conversion Device

[0001] The present invention relates to a power conversion device.

[0002] A power conversion device converts DC power supplied from a DC power source into AC power by switching a switching element. The power conversion device includes a power conversion circuit body incorporating a switching element for converting power, and a smoothing capacitor provided between the power conversion circuit body and the DC power source to smooth the DC power source output (see, for example, Patent Document 1).

[0003] In power conversion devices, flexible component placement is required due to demands for higher voltages and smaller device size. In the power conversion device described in Patent Document 1, a smoothing capacitor and a power conversion circuit are placed in this order from the DC power supply input side. Then, power from the DC power supply is supplied to the power conversion circuit via the smoothing capacitor by a capacitor bus bar joined to the electrodes of the capacitor element of the smoothing capacitor.

[0004] Japanese Patent No. 4655020

[0005] In the technology of Patent Document 1, the DC power supply input terminal and the power conversion circuit are connected by a capacitor bus bar, i.e., the DC power supply input terminal is connected to the power conversion circuit via a capacitor, making it difficult to shorten the bus bar and limiting the degree of freedom in component placement. Furthermore, since the capacitor bus bar joined to the electrode of the capacitor element is used as the bus bar connecting the DC power supply input terminal and the power conversion circuit, it is susceptible to the influence of heat generated by the capacitor element.

[0006] A power conversion device according to an aspect of the present invention includes a power conversion circuit body that converts DC current into AC current; a smoothing capacitor having a capacitor element housed in a capacitor case and electrically connected to the power conversion circuit body; a housing having a bottom and side walls erected around the bottom and in which the power conversion circuit body and the smoothing capacitor are housed; a DC power supply terminal provided on the side wall and to which DC current is supplied; and a bus bar having a positive conductor and a negative conductor, one end connected to the DC power supply terminal and the other end connected to a DC input terminal of the power conversion circuit body, wherein the smoothing capacitor is disposed between the DC power supply terminal and the power conversion circuit body, and the bus bar is connected to the power conversion circuit body through between the smoothing capacitor and the bottom.

[0007] According to the present invention, it is possible to shorten the bus bar.

[0008] Fig. 1 is a plan view showing a schematic configuration of a power conversion device according to this embodiment. Fig. 2 is an exploded perspective view of the power conversion device. Fig. 3 is a perspective view of a third bus bar. Fig. 4 is a plan view of the power conversion circuit body as seen from above the housing. Fig. 5 is a perspective view of a smoothing capacitor. Fig. 6 is a view of the storage area for the smoothing capacitor within the housing as seen from above the housing. Fig. 7 is a cross-sectional view showing the arrangement of the smoothing capacitor and the third bus bar within the recess.

[0009] Hereinafter, an embodiment of a semiconductor device according to the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. Furthermore, in the following description, identical or similar elements and processes are given the same reference numerals, and duplicate explanations may be omitted. Note that the content described below merely shows one example of an embodiment of the present invention, and the present invention is not limited to the following embodiment, and can be implemented in various other forms.

[0010] 1 and 2 are diagrams showing a schematic configuration of a power conversion device 100 according to this embodiment. FIG. 1 is a plan view of the power conversion device 100. FIG. 2 is an exploded perspective view of the power conversion device 100. The power conversion device 100 includes a power conversion circuit 3 that converts direct current (DC) to alternating current (AC) and a smoothing capacitor 2. The power conversion circuit 3, the smoothing capacitor 2, and other components provided in the power conversion device 100 are housed in a housing 4. The housing 4 is a casing consisting of a bottom 41 and a side wall 42 that stands upright and surrounds the periphery of the bottom 41. Although not shown in FIGS. 1 and 2, a cover member that covers an upper opening of the housing 4 is attached to the upper end of the side wall 42.

[0011] The smoothing capacitor 2 and the power conversion circuit 3 are arranged side by side in the vertical direction (y direction) in the drawing within the housing 4. A DC power supply terminal 1 connected to a DC power supply (e.g., a battery that stores driving power) (not shown) is provided on the lower side wall 42 of the housing 4. The DC power supply terminal 1 is connected to the power conversion circuit 3 via DC transmission bus bars 5 (5a, 5b, 5c).

[0012] The DC transmission bus bar 5 is composed of a first bus bar 5a, a second bus bar 5b, and a third bus bar 5c connected in series. Each of the bus bars 5a to 5c has a positive conductor and a negative conductor. The first bus bar 5a connects the DC power supply terminal 1 to the second bus bar 5b. The third bus bar 5c connects the second bus bar 5b to the power conversion circuit body 3.

[0013] The second bus bar 5b extends in the x-direction within the housing 4 and has a shape and terminals for connecting a filter component (e.g., a ferrite core) 60 for removing noise, an X capacitor 61, and a Y capacitor 62. The filter component 60, the X capacitor 61, and the Y capacitor 62 are arranged side by side in the x-direction in the gap between the smoothing capacitor 2 and the side wall 42 on which the DC power supply terminal 1 is provided. Although not shown in FIG. 1 , a recess 44 (see FIG. 2 ) in which the smoothing capacitor 2 is disposed is formed in the bottom 41 of the housing 4. The third bus bar 5c passes below the smoothing capacitor 2 and is connected to the power conversion circuit body 3.

[0014] The power conversion circuit 3 includes a plurality of semiconductor modules and converts DC current into AC current by controlling the switching operation of the semiconductor modules. As shown in Figure 2, a coolant flow path 43 is provided in the housing 4, and the heat sink 300 (see Figure 7 described later) of each semiconductor module is inserted into the coolant flow path 43 through an opening thereof. This opening is sealed when the power conversion circuit 3 is fixed to the housing 4. A coolant inlet 431 and a coolant outlet 432 are formed in the housing 4. The coolant is introduced into the coolant flow path 43 from the coolant inlet 431, and the coolant that has flowed through the coolant flow path 43 is discharged from the coolant outlet 432.

[0015] The AC output terminals 34U, 34V, 34W (see FIG. 4 ) of the power conversion circuit body 3 are connected to the AC transmission bus bar 7. The AC transmission bus bar 7 is connected to, for example, a drive motor of an electric vehicle. A connection opening 421 is provided in the housing 4, and a motor cable having a connection terminal is inserted into the housing through this connection opening 421 and connected to the AC transmission bus bar 7.

[0016] 3 is a perspective view of the third bus bar 5c. The third bus bar 5c is molded with a molding resin material 50 except for the terminal portion. As described above, the third bus bar 5c has a positive conductor 51 and a negative conductor 52. As indicated by the dashed lines, the positive conductor 51 and the negative conductor 52 are resin-molded and arranged side by side in the x direction with a gap therebetween.

[0017] The positive and negative conductors 51 and 52 have bottom surfaces 51b and 52b that face the underside of the smoothing capacitor 2, first upright portions 51a and 52a that extend upward from the DC power supply side of the bottom surfaces 51b and 52b, and second upright portions 51c and 52c that extend upward from the power conversion circuit side of the bottom surfaces 51b and 52b. The smoothing capacitor 2 shown in FIGS. 1 and 2 is disposed in the space between the first upright portions 51a and 52a and the second upright portions 51c and 52c.

[0018] A positive terminal 511 and a negative terminal 521 connected to the DC power supply (second bus bar 5b) are formed at the upper ends of the first upright portions 51a and 52a, and a positive terminal 512 and a negative terminal 522 connected to the power conversion circuit are formed at the upper ends of the second upright portions 51c and 52c. The terminals 511, 512, 521, and 522 are exposed from the molding resin material 50. As shown in FIG. 3 , the bottom portions 51b and 52b are bent in the xy plane, and the terminals 511 and 521 and the terminals 512 and 522 are misaligned in the x direction.

[0019] 4 is a plan view of the power conversion circuit body 3 as viewed from above (the positive side in the z direction) of the housing 4. The semiconductor modules 30 constituting the upper and lower arms of the U-phase, V-phase, and W-phase are disposed below the circuit board 31 in the z direction. The power conversion circuit body 3 is fixed to the housing 4 by bolting a plurality of fixing portions 35 to the housing 4.

[0020] DC input positive terminals 32U, 32V, 32W and DC input negative terminals 33U, 33V, 33W corresponding to the U, V, and W phases are provided on the smoothing capacitor side (negative side in the y direction) of the power conversion circuit 3. On the other hand, AC output terminals 34U, 34V, 34W from which AC current converted by the power conversion circuit 3 is output are provided on the AC transmission bus bar side of the power conversion circuit 3.

[0021] The DC input positive terminals 32U, 32V, and 32W are terminals provided on the same positive conductive member provided in the power conversion circuit 3. Similarly, the DC input negative terminals 33U, 33V, and 33W are terminals provided on the same negative conductive member provided in the power conversion circuit 3. In this manner, three pairs of positive and negative terminals (32U, 33U), (32V, 33V), and (32W, 33W) are provided on the input side of the power conversion circuit 3. The input from the DC power supply terminal 1 is connected to at least one of the three pairs of positive and negative terminals (32U, 33U), (32V, 33V), and (32W, 33W).

[0022] As shown in Figures 1 and 2 and Figure 6 described later, in this embodiment, the positive terminal 512 and the negative terminal 522 of the third bus bar 5c are connected to the positive and negative terminal pair (32V, 33V) of the power conversion circuit body 3, i.e., the DC input positive terminal 32V and the DC input negative terminal 33V.

[0023] 5 is a perspective view of the smoothing capacitor 2. The smoothing capacitor 2 includes a capacitor case 20, a capacitor element (not shown) housed in the capacitor case 20, a positive bus bar 21, and a negative bus bar 22. The capacitor case 20 is a rectangular parallelepiped case having an opening 200, and is made of, for example, resin. The capacitor case 20 is fixed to the housing 4 by bolting a plurality of fixing portions 201 formed on the outer periphery of the capacitor case 20 to the housing 4.

[0024] The capacitor element (e.g., an element wrapped in a film) housed in the capacitor case 20 through the opening 200, the positive bus bar 21, and the negative bus bar 22 are sealed with sealing resin (e.g., potting resin) 23. Only the terminals (capacitor positive terminal 210 and capacitor negative terminal 220) of the positive bus bar 21 and the negative bus bar 22 are exposed from the sealing resin 23. The smoothing capacitor 2 is disposed in the housing 4 so that the opening 200 faces the power conversion circuit 3. The capacitor positive terminals 210 are connected to the DC input positive terminals 32U, 32V, and 32W of the power conversion circuit 3, and the capacitor negative terminals 220 are connected to the DC input negative terminals 33U, 33V, and 33W of the power conversion circuit 3.

[0025] 6 is a view of the storage area for the smoothing capacitor 2 in the housing 4 as viewed from above (the positive side in the z direction) of the housing. A recess 44 having a rectangular planar shape is formed in the bottom 41 (see FIG. 1 ) of the housing 4. A substantially L-shaped recess 44a is formed in the bottom surface of the recess 44, in which a portion including bottom surfaces 51b, 52b (see FIG. 3 ) of the positive conductor 51 and the negative conductor 52 of the third bus bar 5c, i.e., a portion of the third bus bar 5c facing the lower surface of the smoothing capacitor 2, is disposed. The third bus bar 5c is bent along the bottom surface (i.e., the recess 44a) and side surface of the recess 44, and one connection terminal (positive terminal 511 and negative terminal 521) is connected to the second bus bar 5b, and the other connection terminal (positive terminal 512 and negative terminal 522) is connected to the DC input terminals (DC input positive terminal 32V and DC input negative terminal 33V) of the power conversion circuit 3.

[0026] 6, the three pairs of positive and negative terminals (32U, 33U), (32V, 33V), and (32W, 33W) of the power conversion circuit 3 are aligned in the left-right direction (x direction) in the figure. That is, they are arranged in parallel to face the smoothing capacitor 2. However, due to the component arrangement, the parallel positions (x direction positions) of the pairs of positive and negative terminals (32U, 33U), (32V, 33V), and (32W, 33W) do not necessarily coincide with the x direction positions of the terminals of the second bus bar 5b connected to the third bus bar 5c.

[0027] In this embodiment, the x-direction positions of the connection terminals at both ends of the divided third bus bar 5c, i.e., the x-direction positions of the terminals 511, 521 on the second bus bar side and the terminals 512, 522 on the power conversion circuit side, are set to be different, so that the third bus bar 5c can absorb any misalignment in the connection positions between the second bus bar side and the power conversion circuit side. As a result, the degree of freedom in component arrangement is improved, and the third bus bar 5c can easily connect the terminals 511, 521 on the second bus bar side and the terminals 512, 522 on the power conversion circuit side.

[0028] When connecting the third bus bar 5c to the power conversion circuit 3, the length of the third bus bar 5c can be reduced by connecting it to the pair of the three positive and negative terminal pairs (32U, 33U), (32V, 33V), and (32W, 33W) whose terminal position in the x direction is closest to that of the second bus bar 5b. This makes it possible to suppress self-heating of the third bus bar 5c.

[0029] The DC input positive terminals 32U, 32V, and 32W and the DC input negative terminals 33U, 33V, and 33W of the power conversion circuit 3 are each provided on the same three-phase conductive member (bus bar). Therefore, the third bus bar 5c can be connected to any of the U-phase, V-phase, and W-phase terminals. However, connecting the third bus bar 5c to the U-phase terminals 32U and 33U or the W-phase terminals 32W and 33W, which are provided on the left and right sides of the conductive member, can cause a deterioration in inductance. On the other hand, as shown in FIG. 6 , connecting the third bus bar 5c to the V-phase terminals 32V and 33V, which are provided at approximately the center of the three pairs of positive and negative terminals (32U, 33U), (32V, 33V), and (32W, 33W) arranged in parallel in the x direction, i.e., at the center of the conductive member in the left-right direction, can prevent the deterioration in inductance.

[0030] As described above, from the viewpoint of shortening the third bus bar 5c and preventing deterioration of inductance on the input side of the power conversion circuit body 3, it is preferable that the x-direction position of the connection point between the third bus bar 5c and the second bus bar 5b be as identical as possible to the centrally located terminal (V-phase terminals 32V, 33V).

[0031] 7 is a diagram showing the arrangement of the smoothing capacitor 2 and the third bus bar 5c in the recess 44 of the housing 4, and corresponds to the cross section A-A in FIG. 1. As described above, the positive conductor 51 and the negative conductor 52 of the third bus bar 5c include bottom surface portions 51b, 52b that face the lower surface of the smoothing capacitor 2, and first upright portions 51a, 52a and second upright portions 51c, 52c that stand on either side of the bottom surface portions 51b, 52b. In FIG. 7, the portion of the third bus bar 5c where the bottom surface portions 51b, 52b are molded is represented as bottom surface portion 5c2, the portion where the first upright portions 51a, 52a are molded is represented as upright portion 5c1, and the portion where the second upright portions 51c, 52c are molded is represented as upright portion 5c3.

[0032] A recess 44 is formed in the bottom 41 of the housing 4. As shown in FIG. 6 , a recess 44a is further formed in the bottom surface of this recess 44, in which the bottom portion 5c2 of the third bus bar 5c is disposed. The third bus bar 5c is bent to fit along the inner wall of the recess 44, and the bottom portion 5c2 is disposed between the bottom surface of the smoothing capacitor 2 and the bottom surface of the recess 44a. A potting resin 440 is filled in the recess 44. The portions of the third bus bar 5c and the smoothing capacitor 2 that are disposed in the recess 44 are embedded in the potting resin 440.

[0033] By embedding the third bus bar 5c in the potting resin 440 in this manner, the potting resin 440 fills the gaps between the third bus bar 5c, the smoothing capacitor 2, and the recess 44, and the heat generated in the third bus bar 5c and the smoothing capacitor 2 can be effectively dissipated to the housing 4. In other words, the heat from the third bus bar 5c and the smoothing capacitor 2 can be dissipated to the potting resin 440 and the housing 4 without passing through an air layer that would hinder heat transfer, thereby improving the heat dissipation effect.

[0034] 6, the terminals 512, 522 of the third bus bar 5c are connected to the DC input positive terminal 32V and the DC input negative terminal 33V of the power conversion circuit body 3, and these terminals 32V, 33V are also connected to the capacitor positive terminal 210 and the capacitor negative terminal 220 of the smoothing capacitor 2. The three overlapping terminals 32V, 512, 210 are fastened together and fixed with bolts, and similarly, the three overlapping terminals 33V, 522, 220 are fastened together and fixed with bolts.

[0035] As shown in Figure 7, the smoothing capacitor 2 is arranged so that the opening 200 of the capacitor case 20 faces the power conversion circuit body 3. The capacitor positive terminal 210 and the capacitor negative terminal 220 protrude straight from the sealing resin 23 toward the power conversion circuit body 3. Therefore, the capacitor positive terminal 210 and the capacitor negative terminal 220 are connected to the terminals 32V, 33V of the power conversion circuit body 3 at the shortest distance. Furthermore, the capacitor positive terminal 210 and the capacitor negative terminal 220 are fastened together with the terminals 512, 522 of the third bus bar 5c to the terminals 32V, 33V of the power conversion circuit body 3. This reduces the number of steps required for terminal connection.

[0036] A refrigerant flow path 43 into which the heat sink 300 of the power conversion circuit body 3 is inserted is formed in an area of ​​the bottom 41 where the power conversion circuit body 3 is fixed. Therefore, heat generated in the standing portion 5c3 of the third bus bar 5c is dissipated to the housing 4 (bottom 41) via the potting resin 400 in the recess 44, and is also dissipated to the refrigerant from the terminals 512, 522 via the power conversion circuit body 3. On the other hand, heat generated in the standing portion 5c1 is dissipated mainly to the bottom 41 of the housing 4 via the potting resin 400.

[0037] Therefore, the height of the positive terminal 511 of the standing portion 5c1 (height distance h1 from the bottom surface of the recess 44) is set smaller than the height of the positive terminal 512 of the standing portion 5c3 (height distance h2 from the bottom surface of the recess 44). Similarly, the heights of the negative terminals 521, 522 are set similarly. As a result, the conductor length of the standing portion 5c1 is shortened, which suppresses heat generation and improves the efficiency of heat dissipation to the potting resin 400 and the bottom 41.

[0038] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0039] (1) As shown in FIGS. 1 to 5 and the like, the power conversion device 100 includes a power conversion circuit 3 that converts DC current into AC current, a smoothing capacitor 2 that has a capacitor element housed in a capacitor case 20 and is electrically connected to the power conversion circuit 3, a housing 4 that has a bottom 41 and side walls 42 that are erected around the bottom 41 and that houses the power conversion circuit 3 and the smoothing capacitor 2, DC power supply terminals 1 that are provided on the side walls 42 and to which DC current is supplied, a positive conductor 51 and a negative conductor and a bus bar (third bus bar 5c) having a body 52, one end (positive terminal 511 and negative terminal 521) connected to the DC power supply terminal 1 and the other end (positive terminal 512 and negative terminal 522) connected to the DC input terminals (DC input positive terminal 32V, DC input negative terminal 33V) of the power conversion circuit body 3, the smoothing capacitor 2 being disposed between the DC power supply terminal 1 and the power conversion circuit body 3, and the third bus bar 5c being connected to the power conversion circuit body 3 through a gap between the smoothing capacitor 2 and the bottom 41.

[0040] In this configuration in which the smoothing capacitor 2 is disposed between the DC power supply terminal 1 and the power conversion circuit body 3, the third bus bar 5c connecting the DC power supply terminal 1 and the power conversion circuit body 3 is connected to the power conversion circuit body 3 by passing between the smoothing capacitor 2 and the bottom 41, thereby reducing the length of the third bus bar 5c. Furthermore, because the third bus bar 5c is connected to the power conversion circuit body 3 without passing through the smoothing capacitor 2, the degree of freedom in component placement can be improved. Furthermore, because the bus bar intermediate region is sandwiched between the smoothing capacitor 2 and the bottom 41, vibration of the bus bar intermediate region can be suppressed.

[0041] For example, if the bus bar is connected to the power conversion circuit 3 so as to bypass the side of the smoothing capacitor 2, the bus bar becomes longer by the length of the bypass. Also, if the bus bar is connected to the power conversion circuit 3 by passing above the smoothing capacitor 2, it is necessary to fix the bus bar above the smoothing capacitor 2, which increases the height dimension of the housing 4, i.e., tends to lead to an increase in the size of the power conversion device.

[0042] (2) In the above (1), as shown in FIG. 7 and other figures, a recess 44 that accommodates the smoothing capacitor 2 is formed in the bottom 41, and the third bus bar 5c is bent within the recess 44 to fit along the inner wall of the recess. By bending the third bus bar 5c to fit along the inner wall of the recess 44 in this manner, the third bus bar 5c that passes between the smoothing capacitor 2 and the bottom 41 can be brought into close contact with both the inner wall of the recess and the outer wall of the capacitor case 20. This reduces the space required for arranging the third bus bar 5c, thereby enabling the power conversion device to be made more compact. Furthermore, heat generated by the smoothing capacitor 2 and the third bus bar 5c can be effectively transferred to the housing 4.

[0043] (3) In the above (2), as shown in Fig. 7 and other figures, the recess 44 is filled with a resin member (potting resin 400), and the smoothing capacitor 2 and the third bus bar 5c are embedded in the potting resin 400 within the recess 44. By embedding the smoothing capacitor 2 and the third bus bar 5c in the potting resin 400, the potting resin 400 fills the gap between the smoothing capacitor 2, the third bus bar 5c, and the recess 44, and heat generated in the smoothing capacitor 2 and the third bus bar 5c can be effectively dissipated to the housing 4 (bottom 41).

[0044] 5, 7, etc., the capacitor case 20 has an opening 200 facing the power conversion circuit body 3, the smoothing capacitor 2 has capacitor terminals (a capacitor positive terminal 210 and a capacitor negative terminal 220) protruding from the opening 200 toward the power conversion circuit body 3, and the capacitor positive terminal 210 and the capacitor negative terminal 220 are fastened together with the other end (a positive terminal 512 and a negative terminal 522) of the third bus bar 5c to the DC input terminals (a DC input positive terminal 32V and a DC input negative terminal 33V) of the power conversion circuit body 3. Therefore, the capacitor positive terminal 210 and the capacitor negative terminal 220 are connected to the terminals 32V, 33V of the power conversion circuit body 3 in the shortest distance, and the number of steps for connecting the terminals can be reduced.

[0045] (5) In the above (2), as shown in Fig. 7 and other figures, the height direction distance h1 from the bottom surface of the recess 44 to one end (positive terminal 511) is smaller than the height direction distance h2 from the bottom surface of the recess 44 to the other end (positive terminal 512). As a result, heat generation in the bus bar region extending from the positive terminal 511 to the inner wall of the recess 44 is suppressed, and the efficiency of heat dissipation to the bottom 41 of the housing 4 can be improved.

[0046] (6) In the above (1), as shown in FIG. 6 and other figures, the power conversion circuit 3 has a plurality of DC input terminals (three pairs of positive and negative terminals (32U, 33U), (32V, 33V), (32W, 33W)) arranged in parallel to face the smoothing capacitor 2, and one end (positive terminal 511 and negative terminal 521) of the third bus bar 5c and the other end (positive terminal 512 and negative terminal 522) of the third bus bar 5c are misaligned with respect to the direction of parallel arrangement of the DC input terminals. By shaping the third bus bar 5c in this way, even if there is a misalignment in the connection position between the second bus bar side and the power conversion circuit side, the misalignment can be absorbed by the third bus bar 5c, improving the degree of freedom in component arrangement.

[0047] (7) In the above (6), as shown in FIG. 6 and other figures, the multiple DC input terminals (three pairs of positive and negative terminals (32U, 33U), (32V, 33V), (32W, 33W)) are terminals formed on the same conductive material, and the other end of the third bus bar 5c (positive terminal 512 and negative terminal 522) is connected to the DC input terminal (positive and negative terminal pair (32V, 33V)) closest to the center position of the parallel arrangement. By connecting them in this way, it is possible to prevent deterioration of inductance.

[0048] The above-described embodiments and various modifications are merely examples, and the present invention is not limited to these, as long as the features of the invention are not impaired. Other embodiments that can be conceived within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0049] 1...DC power supply terminal, 2...smoothing capacitor, 3...power conversion circuit body, 4...casing, 5...DC transmission bus bar, 5a...first bus bar, 5b...second bus bar, 5c...third bus bar, 20...capacitor case, 32U, 32V, 32W...DC input positive terminal, 33U, 33V, 33W...DC input negative terminal, 34U, 34V, 34W...AC output terminal, 41...bottom, 42...side wall, 4 3... refrigerant flow path, 44, 44a... recess, 51... positive electrode conductor, 52... negative electrode conductor, 51a, 52a... first standing portion, 51b, 52b... bottom surface portion, 51c, 52c... second standing portion, 100... power conversion device, 200... opening, 210... capacitor positive electrode terminal, 220... capacitor negative electrode terminal, 400... potting resin, 511, 512... positive electrode terminal, 521, 522... negative electrode terminal

Claims

1. A power conversion device comprising: a power conversion circuit that converts direct current into alternating current; a smoothing capacitor having a capacitor element housed in a capacitor case and electrically connected to the power conversion circuit; a housing having a bottom and side walls erected around the bottom and housing the power conversion circuit and the smoothing capacitor; a DC power supply terminal provided on the side wall and to which DC current is supplied; and a bus bar having a positive conductor and a negative conductor, one end connected to the DC power supply terminal and the other end connected to a DC input terminal of the power conversion circuit, wherein the smoothing capacitor is disposed between the DC power supply terminal and the power conversion circuit, and the bus bar is connected to the power conversion circuit through a gap between the smoothing capacitor and the bottom.

2. A power conversion device according to claim 1, wherein a recess for accommodating the smoothing capacitor is formed in the bottom, and the bus bar is bent within the recess so as to follow the inner wall of the recess.

3. A power conversion device according to claim 2, wherein the recess is filled with a resin material, and the smoothing capacitor and the bus bar are embedded in the resin material within the recess.

4. A power conversion device according to claim 1, wherein the capacitor case has an opening facing the power conversion circuit body, the smoothing capacitor has a capacitor terminal protruding from the opening towards the power conversion circuit body, and the capacitor terminal is fastened together with the other end of the bus bar to the DC input terminal of the power conversion circuit body.

5. A power conversion device according to claim 2, wherein the height distance from the bottom surface of the recess to the one end is smaller than the height distance from the bottom surface of the recess to the other end.

6. A power conversion device according to claim 1, wherein the power conversion circuit body has a plurality of the DC input terminals arranged in parallel so as to face the smoothing capacitor, and the one end and the other end of the bus bar are misaligned with respect to the direction of the parallel arrangement.

7. A power conversion device according to claim 6, wherein the plurality of DC input terminals are terminals formed on the same conductive member, and the other end of the bus bar is connected to the DC input terminal that is closest to the center position of the parallel arrangement.

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