Power conversion device

Abstract

To provide a technique for a power conversion device in which a plurality of switch legs formed of semiconductor switches corresponding to upper and lower arms are connected in parallel, for suppressing unbalanced current flowing in each semiconductor switch.SOLUTION: A power conversion device 1 according to one embodiment of the present disclosure includes a U-phase positive electrode side DC bus bar 41P, a U-phase negative electrode side DC bus bar 41N, and a U-phase parallel connection bus bar 41O1 that respectively connect between positive electrode side terminals 410P of a plurality of switch modules 410, between negative electrode side terminals 410N thereof, and between AC output terminals 410O thereof. These bus bars constitute a U-phase laminate bus bar 41PNO with a laminate structure in which layers are stacked through an insulating layer 41I1. In the U-phase parallel connection bus bar 41O1, the lengths of the routes between all the arms included in the switch modules 410 and a merge part where all the routes from the respective switch modules 410 merge are substantially equal.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, in a power conversion device in which a plurality of switch legs each composed of semiconductor switches corresponding to upper and lower arms are connected in parallel, a technique for equalizing the currents flowing through each semiconductor switch is known (see, for example, Patent Document 1).

[0003] In Patent Document 1, each switch leg is arranged in the width direction, and a parallel connection bus bar for connecting connection points between the upper and lower arms of each switch leg in parallel and an output bus bar connected to the parallel connection bus bar are provided. The parallel connection bus bar occupies a range in the width direction in which each switch leg is arranged and is provided so as to extend in the length direction from each switch leg. And the output bus bar is provided so as to be laminated via an insulating layer with the parallel connection bus bar at the other end of each switch leg in the length direction of the parallel connection bus bar and to extend in the width direction, and is connected to the parallel connection bus bar at one end in the width direction.

[0004] Thereby, in Patent Document 1, the current flowing through the parallel connection bus bar (that is, the current merging from each switch leg or the current branching to each switch leg) and the current flowing through the output bus bar are opposite to each other, and the magnetic fields generated by each can be canceled out. Therefore, the inductance of the power path in the width direction of the parallel connection bus bar when the currents of each switch leg merge or branch is reduced, and the imbalance of the currents flowing through each switch leg can be suppressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in Patent Document 1, while the current in the output bus bar corresponds to the sum of the currents in all the switch legs, the current flowing in the width direction at the other end of the parallel connection bus bar is only the sum of the current passing through one switch leg or the currents in some of the switch legs. Therefore, there is a possibility that the magnetic field generated by the output bus bar is not canceled out by the magnetic field generated by the parallel connection bus bar and remains. Thus, when this magnetic field intersects with the current flowing in the width direction of the parallel connection bus bar, inductance is generated in the current path in the width direction of the parallel connection bus bar, and an imbalance may occur in the currents flowing through the respective switch legs.

[0007] Therefore, in view of the above problems, an object of the present invention is to provide a technique capable of suppressing an imbalance in the currents flowing through each semiconductor switch in a power conversion device in which a plurality of switch legs each composed of semiconductor switches corresponding to upper and lower arms are connected in parallel.

Means for Solving the Problems

[0008] To achieve the above object, in one embodiment of the present disclosure, a smoothing circuit, a bridge circuit including an inverter circuit that outputs predetermined AC power based on DC power input from the smoothing circuit, in which a plurality of switch legs in which upper and lower arms including a plurality of semiconductor switches are connected in series are connected in parallel, and output circuits in which connection points of the upper and lower arms of each of the plurality of switch legs are connected are connected in parallel in a multi-phase manner, and output terminals for outputting the predetermined AC power to the outside. The inverter circuit includes a positive-side DC bus bar that connects the positive-side terminals of the plurality of switch legs, a negative-side DC bus bar that connects the negative-side terminals of the plurality of switch legs, and a parallel connection bus bar that connects the connection points of the upper and lower arms of each of the plurality of switch legs. The positive electrode side DC bus bar and the negative electrode side DC bus bar have a laminated structure laminated via an insulating layer. The bus bar for parallel connection is configured such that the lengths of the respective paths between all the arms included in the plurality of switch legs and the confluence portion where all the paths from each of the plurality of switch legs converge are substantially equal. 、 The parallel connection bus bar is two switch legs included in a plurality of the switch legs, and the paths from the two switch legs arranged side by side in one axial direction parallel to the plane in which the two switch legs are arranged merge at a substantially central position between the connection points of the two switch legs in the one axial direction toward the output terminal. The plurality of the switch legs include a plurality of combinations of the two switch legs. The parallel connection bus bar is configured to merge the paths from each of the two switch legs for each of the plurality of combinations toward the output terminal, and the lengths of the respective paths between the merging portions are substantially equal. The plurality of the switch legs are arranged in two rows in another axial direction perpendicular to the one axial direction and parallel to the plane in which the two switch legs are arranged with the two switch legs of two sets aligned in the one axial direction. The parallel connection bus bar is configured to be substantially plane-symmetric with respect to the vertical plane at the central position of the two switch legs in the one axial direction, and is configured to be substantially plane-symmetric with respect to the vertical plane at the central position of the two sets in the other axial direction. Further, the connection portion with the wiring up to the output terminal is configured to be at a substantially central position between the four switch legs included in the two sets in the one axial direction and the other axial direction. are. A power conversion device is provided.

Advantages of the Invention

[0011] According to the above-described embodiment, in a power conversion device in which a plurality of switch legs each composed of semiconductor switches corresponding to upper and lower arms are connected in parallel, it is possible to provide a technique capable of suppressing an imbalance in the current flowing through each semiconductor switch.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments will be described with reference to the drawings.

[0014] [First Embodiment] First, the first embodiment will be described with reference to FIGS. 1 to 6.

[0015] [Overview of the Power Conversion Device] FIG. 1 is a circuit diagram showing an example of a power conversion device 1 according to the first embodiment.

[0016] The power conversion device 1 generates predetermined three-phase AC power using three-phase AC power input from a predetermined external power source (for example, a commercial power supply system), and supplies the generated three-phase AC power to a predetermined load device (for example, an electric motor).

[0017] As shown in FIG. 1, the power conversion device 1 includes a rectifier circuit 10, a smoothing circuit 20, a fuse 30, and an inverter circuit 40.

[0018] The rectifier circuit 10 rectifies the three-phase AC power of the R phase, S phase, and T phase input from the external power source through the input terminal 11, and outputs the predetermined DC power to the smoothing circuit 20.

[0019] The input terminal 11 includes an R-phase input terminal 111 to which R-phase power is input, an S-phase input terminal 112 to which S-phase power is input, and a T-phase input terminal 113 to which T-phase power is input.

[0020] As shown in FIG. 1, the rectifier circuit 10 is, for example, a bridge-type full-wave rectifier circuit in which six diodes 12 are connected in a bridge shape.

[0021] The smoothing circuit 20 smooths the DC power output from the rectifier circuit 10 and the DC power regenerated from the inverter circuit 40.

[0022] The smoothing circuit 20 includes a positive electrode side bus bar 20P, a negative electrode side bus bar 20N, and a smoothing capacitor 21.

[0023] The positive electrode side bus bar 20P is a flat member made of a material with relatively high conductivity (for example, copper, aluminum, etc.). Hereinafter, the same applies to the negative electrode side bus bar 20N, the U-phase positive electrode side DC bus bar 41P, the U-phase negative electrode side DC bus bar 41N, the V-phase positive electrode side DC bus bar 42P, the V-phase negative electrode side DC bus bar 42N, the W-phase positive electrode side DC bus bar 43P, and the W-phase negative electrode side DC bus bar 43N, which will be described later.

[0024] The positive electrode side bus bar 20P is connected to each of the positive electrode side output end of the rectifier circuit 10 and the positive electrode side input end of the inverter circuit 40.

[0025] The negative electrode side bus bar 20N is connected to the negative electrode side output end of the rectifier circuit 10 and the negative electrode side DC input end of the inverter circuit 40.

[0026] The smoothing capacitor 21 is arranged in a power path connecting the positive electrode side bus bar 20P and the negative electrode side bus bar 20N in parallel with the rectifier circuit 10 and the inverter circuit 40. The smoothing capacitor 21 smooths the DC power output from the rectifier circuit 10 and the inverter circuit 40 while appropriately repeating charge and discharge.

[0027] The smoothing capacitor 21 may be one, or a plurality of smoothing capacitors 21 may be connected in parallel (see FIGS. 2 and 3).

[0028] The smoothing capacitor 21 includes a positive electrode side terminal 21P connected to the positive electrode side bus bar 20P and a negative electrode side terminal 21N connected to the negative electrode side bus bar 20N.

[0029] The fuse 30 is disposed on the positive electrode side power path between the positive electrode side bus bar 20P and the positive electrode side DC input terminal of the inverter circuit 40. The fuse 30 melts when an overcurrent or the like occurs, and protects the power conversion device 1 (inverter circuit 40) from damage caused by an overcurrent associated with an overload, a short circuit, or the like.

[0030] The inverter circuit 40 generates three-phase AC power of the U-phase, V-phase, and W-phase from the DC power supplied from the smoothing circuit 20, and outputs it from the output terminal 40T to an external load device. The output terminal 40T includes a U-phase output terminal 41T that outputs the U-phase AC power to the outside, a V-phase output terminal 42T that outputs the V-phase AC power to the outside, and a W-phase output terminal 43T that outputs the W-phase AC power to the outside.

[0031] The inverter circuit 40 includes a bridge circuit composed of a U-phase circuit 41, a V-phase circuit 42, and a W-phase circuit 43. The U-phase circuit 41, the V-phase circuit 42, and the W-phase circuit 43 (each being an example of an output circuit) are connected in parallel between the positive electrode side wiring and the negative electrode side wiring of the power conversion device 1.

[0032] The U-phase circuit 41 includes a U-phase positive electrode side DC bus bar 41P, a U-phase negative electrode side DC bus bar 41N, switch modules 411 to 414, and a U-phase AC bus bar 41O. Hereinafter, in the first embodiment, the switch modules 411 to 414 may be collectively or any one of the switch modules 411 to 414 may be individually referred to as "switch module 410".

[0033] The U-phase positive electrode side DC bus bar 41P is connected to the positive electrode side bus bar 20P of the smoothing circuit 20 via the fuse 30.

[0034] The U-phase negative-side DC bus bar 41N is connected to the negative-side bus bar 20N of the smoothing circuit 20.

[0035] The switch modules 411 to 414 (an example of a switch leg) are connected in parallel between the U-phase positive-side DC bus bar 41P and the U-phase negative-side DC bus bar 41N.

[0036] The switch module 411 includes semiconductor switches 411s1 and 411s2 corresponding to the upper and lower arms, freewheeling diodes 411d1 and 411d2, a positive-side terminal 411P, a negative-side terminal 411N, and an AC output terminal 411O.

[0037] The switch module 412 includes semiconductor switches 412s1 and 412s2 corresponding to the upper and lower arms, freewheeling diodes 412d1 and 412d2, a positive-side terminal 412P, a negative-side terminal 412N, and an AC output terminal 412O.

[0038] The switch module 413 includes semiconductor switches 413s1 and 413s2 corresponding to the upper and lower arms, freewheeling diodes 413d1 and 413d2, a positive-side terminal 413P, a negative-side terminal 413N, and an AC output terminal 413O.

[0039] The switch module 414 includes semiconductor switches 414s1 and 414s2 corresponding to the upper and lower arms, freewheeling diodes 414d1 and 414d2, a positive-side terminal 414P, a negative-side terminal 414N, and an AC output terminal 414O.

[0040] In the following, in the first embodiment, the semiconductor switches 411s1, 411s2, 412s1, 412s2, 413s1, 413s2, 414s1, 414s2 may be collectively referred to as "semiconductor switch 410s", or any one of them may be individually referred to as such. Also, in the first embodiment, the components corresponding to the positive terminals 411P to 414P of the above-mentioned "switch module 410" may be referred to as "positive terminal 410P". Further, in the first embodiment, the components corresponding to the negative terminals 411N to 414N of the above-mentioned "switch module 410" may be referred to as "negative terminal 410N". Moreover, in the first embodiment, the components corresponding to the AC output terminals 411O to 414O of the above-mentioned "switch module 410" may be referred to as "AC output terminal 410O".

[0041] Since the switch modules 411 to 414 have the same components and are configured by the same circuit, the switch module 411 will be described as a representative, and the descriptions of the switch modules 412 to 414 will be omitted.

[0042] The semiconductor switches 411s1, 411s2 (an example of the upper and lower arms) are arranged in the power path connecting between the positive terminal 411P and the negative terminal 411N, and are connected in series with each other. The semiconductor switches 411s1, 411s2 are, for example, IGBTs (Insulated Gate Bipolar Transistors).

[0043] The semiconductor switch 411s1 corresponds to the upper arm of the switch leg and is connected to the positive terminal 411P.

[0044] The semiconductor switch 411s2 corresponds to the lower arm of the switch leg and is connected to the negative terminal 411N.

[0045] The freewheeling diodes 411d1, 411d2 are connected in parallel with each of the semiconductor switches 411s1, 411s2.

[0046] The positive terminal 411P is connected to the U-phase positive DC busbar 41P.

[0047] The negative terminal 411N on the negative electrode side is connected to the U-phase negative DC bus bar 41N.

[0048] The AC output terminal 411O (an example of the connection point of the upper and lower arms) is drawn from the connection point (midpoint) between the semiconductor switches 411s1 and 411s2.

[0049] One end of the U-phase AC bus bar 41O connects the respective AC output terminals 411O to 414O of the switch modules 411 to 414 to each other, and the other end is connected to the U-phase output terminal 41T. As a result, the inverter circuit 40 can output the U-phase AC power output from the switch modules 411 to 414 to the outside from the U-phase output terminal 41T.

[0050] The V-phase circuit 42 includes a V-phase positive DC bus bar 42P, a V-phase negative DC bus bar 42N, switch modules 421 to 424, and a V-phase AC bus bar 42O. Hereinafter, in the first embodiment, the switch modules 421 to 424 may be collectively referred to as, or any one of the switch modules 421 to 424 may be individually referred to as, "switch module 420".

[0051] The V-phase positive DC bus bar 42P is connected to the positive bus bar 20P of the smoothing circuit 20 via a fuse 30.

[0052] The V-phase negative DC bus bar 42N is connected to the negative bus bar 20N of the smoothing circuit 20.

[0053] The switch modules 421 to 424 are connected in parallel between the V-phase positive DC bus bar 42P and the V-phase negative DC bus bar 42N.

[0054] The switch module 421 includes semiconductor switches 421s1 and 421s2 corresponding to the upper and lower arms, circulation diodes 421d1 and 421d2, a positive terminal 421P, a negative terminal 421N, and an AC output terminal 421O.

[0055] The switch module 422 includes semiconductor switches 422s1 and 422s2 corresponding to the upper and lower arms, freewheeling diodes 422d1 and 422d2, a positive terminal 422P, a negative terminal 422N, and an AC output terminal 422O.

[0056] The switch module 423 includes semiconductor switches 423s1 and 423s2 corresponding to the upper and lower arms, freewheeling diodes 423d1 and 423d2, a positive terminal 423P, a negative terminal 423N, and an AC output terminal 423O.

[0057] The switch module 424 includes semiconductor switches 424s1 and 424s2 corresponding to the upper and lower arms, freewheeling diodes 424d1 and 424d2, a positive terminal 424P, a negative terminal 424N, and an AC output terminal 424O.

[0058] Hereinafter, in the first embodiment, the semiconductor switches 421s1, 421s2, 422s1, 422s2, 423s1, 423s2, 424s1, and 424s2 may be collectively or any one of them individually referred to as "semiconductor switch 420s". Also, in the first embodiment, the components corresponding to the positive terminals 421P to 424P of the above-mentioned "switch module 420" may be referred to as "positive terminal 420P". Further, in the first embodiment, the components corresponding to the negative terminals 421N to 424N of the above-mentioned "switch module 420" may be referred to as "negative terminal 420N". Moreover, in the first embodiment, the components corresponding to the AC output terminals 421O to 424O of the above-mentioned "switch module 420" may be referred to as "AC output terminal 420O".

[0059] Since the switch modules 421 to 424 have the same components and the same circuit configuration, the switch module 421 will be described as a representative, and the descriptions of the switch modules 422 to 424 will be omitted.

[0060] The semiconductor switches 421s1 and 421s2 (an example of the upper and lower arms) are arranged in a power path connecting between the positive terminal 421P and the negative terminal 421N, and are connected in series with each other.

[0061] The semiconductor switch 421s1 corresponds to the upper arm of the switch leg and is connected to the positive terminal 421P.

[0062] The semiconductor switch 421s2 corresponds to the lower arm of the switch leg and is connected to the negative terminal 421N.

[0063] The freewheeling diodes 421d1 and 421d2 are connected in parallel with the semiconductor switches 421s1 and 421s2 respectively.

[0064] The positive terminal 421P is connected to the V-phase positive DC busbar 42P.

[0065] The negative terminal 421N is connected to the V-phase negative DC busbar 42N.

[0066] The AC output terminal 421O (an example of the connection point of the upper and lower arms) is drawn from the connection point (midpoint) between the semiconductor switches 421s1 and 421s2.

[0067] One end of the V-phase AC busbar 42O connects the respective AC output terminals 421O to 424O of the switch modules 421 to 424, and the other end is connected to the V-phase output terminal 42T. Thereby, the inverter circuit 40 can output the V-phase AC power output from the switch modules 421 to 424 to the outside from the V-phase output terminal 42T.

[0068] The W-phase circuit 43 includes a W-phase positive DC busbar 43P, a W-phase negative DC busbar 43N, switch modules 431 to 434, and a W-phase AC busbar 43O. Hereinafter, in the first embodiment, the switch modules 431 to 434 may be collectively or any one of the switch modules 431 to 434 may be individually referred to as "switch module 430".

[0069] The W-phase positive-side DC bus bar 43P is connected to the positive-side bus bar 20P of the smoothing circuit 20 via the fuse 30.

[0070] The W-phase negative-side DC bus bar 43N is connected to the negative-side bus bar 20N of the smoothing circuit 20.

[0071] The switch modules 431 to 434 are connected in parallel between the W-phase positive-side DC bus bar 43P and the W-phase negative-side DC bus bar 43N.

[0072] The switch module 431 includes semiconductor switches 431s1 and 431s2 corresponding to the upper and lower arms, freewheeling diodes 431d1 and 431d2, a positive-side terminal 431P, a negative-side terminal 431N, and an AC output terminal 431O.

[0073] The switch module 432 includes semiconductor switches 432s1 and 432s2 corresponding to the upper and lower arms, freewheeling diodes 432d1 and 432d2, a positive-side terminal 432P, a negative-side terminal 432N, and an AC output terminal 432O.

[0074] The switch module 433 includes semiconductor switches 433s1 and 433s2 corresponding to the upper and lower arms, freewheeling diodes 433d1 and 433d2, a positive-side terminal 433P, a negative-side terminal 433N, and an AC output terminal 433O.

[0075] The switch module 434 includes semiconductor switches 434s1 and 434s2 corresponding to the upper and lower arms, freewheeling diodes 434d1 and 434d2, a positive-side terminal 434P, a negative-side terminal 434N, and an AC output terminal 434O.

[0076] Hereinafter, in the first embodiment, the semiconductor switches 431s1, 431s2, 432s1, 432s2, 433s1, 433s2, 434s1, 434s2 may be collectively referred to as the "semiconductor switch 430s", or any one of them may be individually referred to as such. Also, in the first embodiment, the components corresponding to the positive terminals 431P to 434P of the above-described "switch module 430" may be referred to as the "positive terminal 430P". Further, in the first embodiment, the components corresponding to the negative terminals 431N to 434N of the above-described "switch module 430" may be referred to as the "negative terminal 430N". Additionally, in the first embodiment, the components corresponding to the AC output terminals 431O to 434O of the above-described "switch module 430" may be referred to as the "AC output terminal 430O".

[0077] Since the switch modules 431 to 434 have the same components and the same circuit configuration, the switch module 431 will be described as a representative, and the descriptions of the switch modules 432 to 434 will be omitted.

[0078] The semiconductor switches 431s1, 431s2 (an example of the upper and lower arms) are arranged in the power path connecting between the positive terminal 431P and the negative terminal 431N, and are connected in series with each other.

[0079] The semiconductor switch 431s1 corresponds to the upper arm of the switch leg and is connected to the positive terminal 431P.

[0080] The semiconductor switch 431s2 corresponds to the lower arm of the switch leg and is connected to the negative terminal 431N.

[0081] The freewheeling diodes 431d1, 431d2 are connected in parallel with the semiconductor switches 431s1, 431s2 respectively.

[0082] The positive terminal 431P is connected to the W-phase positive DC busbar 43P.

[0083] The negative terminal 431N is connected to the W-phase negative DC busbar 43N.

[0084] The AC output terminal 431O (an example of the connection point of the upper and lower arms) is drawn from the connection point (midpoint) between the semiconductor switches 431s1 and 431s2.

[0085] The W-phase AC busbar 43O is connected to the AC output terminals 431O to 434O of the switch modules 431 to 434 at one end, and is connected to the W-phase output terminal 43T at the other end. Thereby, the inverter circuit 40 can output the W-phase AC power output from the switch modules 431 to 434 to the outside from the W-phase output terminal 43T.

[0086] <Structure of the power conversion device> FIG. 2 and FIG. 3 are structural diagrams showing an example of the power conversion device 1 according to the first embodiment. Specifically, FIG. 2 is a perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed, and FIG. 3 is a disassembled perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed and the output terminal 40T is removed and moved upward. FIGS. 4 to 6 are diagrams for explaining an example of the arrangement structure of the busbars. Specifically, FIG. 4 is a disassembled perspective view schematically showing the components of the busbar, FIG. 5 is a perspective view showing the completed state in which the components of the busbar in FIG. 4 are assembled, and FIG. 6 is a side view schematically showing an example of the arrangement structure of the busbar.

[0087] Also, in FIGS. 4 and 5, for the sake of convenience, the laminated bus bar 20PN, the U-phase laminated bus bar 41PN, the V-phase laminated bus bar 42PN, and the W-phase laminated bus bar 43PN are depicted as an integral member. Further, in FIG. 4, for the sake of convenience, the positive electrode side bus bar 20P of the smoothing circuit 20, as well as the U-phase positive electrode side DC bus bar 41P, the V-phase positive electrode side DC bus bar 42P, and the W-phase positive electrode side DC bus bar 43P of the inverter circuit 40 are depicted as an integral member. Similarly, in FIG. 4, for the sake of convenience, the negative electrode side bus bar 20N of the smoothing circuit 20, as well as the U-phase negative electrode side DC bus bar 41N, the V-phase negative electrode side DC bus bar 42N, and the W-phase negative electrode side DC bus bar 43N of the inverter circuit 40 are depicted as an integral member. Similarly, in FIG. 4, the insulating layers 20I1, 41I1, 42I1, 43I1 are depicted as an integral member. Similarly, in FIG. 4, the insulating layers 20I2, 41I2, 42I2, 43I2 are depicted as an integral member. Also, in FIGS. 4 and 5, for simplicity, only a part (4) of all the smoothing capacitors 21 of the smoothing circuit 20 is depicted representatively. Similarly, in FIGS. 4 and 5, for simplicity, only a part (1) of all the switch modules 410 of the U-phase circuit 41 is depicted representatively. Similarly, in FIGS. 4 and 5, for simplicity, only a part (1) of the switch modules 420 included in the V-phase circuit 42 is depicted representatively. Similarly, in FIGS. 4 and 5, for simplicity, only a part (1) of the switch modules 430 included in the W-phase circuit 43 is depicted representatively. Further, in FIG. 6, for the sake of convenience, the depiction of the insulating layers 20I1, 20I2, 41I1, 41I2, 42I1, 42I2, 43I1, 43I2 is omitted.

[0088] As shown in FIGS. 2 and 3, in all of the top view, side view, and front view, various components are housed in a housing 1H having a substantially rectangular and substantially box-shaped configuration. The term "substantially" is intended to allow for manufacturing errors and the like, and will be used in the same sense hereinafter.

[0089] Hereinafter, the longitudinal direction in the top view of the housing 1H may be referred to as the X-axis direction, the short-side direction in the top view of the housing 1H may be referred to as the Y-axis direction, and the vertical direction may be referred to as the Z-axis direction (see FIGS. 2 to 6).

[0090] As shown in FIGS. 2 and 3, the smoothing circuit 20, the fuse 30, and the inverter circuit 40 are arranged in order from one end in the longitudinal direction to the other end (i.e., in the positive X-axis direction) inside the housing 1H.

[0091] Further, the output terminal 40T is arranged at the central portion in the longitudinal direction (X-axis direction) inside the housing 1H and at the upper portion inside the housing 1H. Specifically, the output terminal 40T is arranged above the smoothing circuit 20 and the fuse 30 inside the housing 1H.

[0092] The output terminal 40T includes a U-phase output terminal 41T, a V-phase output terminal 42T, and a W-phase output terminal 43T as described above. The U-phase output terminal 41T, the V-phase output terminal 42T, and the W-phase output terminal 43T are arranged in order from one end in the short-side direction to the central portion (i.e., in the positive Y-axis direction) inside the housing 1H.

[0093] In this example, the smoothing circuit 20 includes 24 smoothing capacitors 21.

[0094] The smoothing capacitor 21 has a substantially cylindrical shape and is placed on the bottom surface of the housing 1H in a manner where the axial direction is along the vertical direction. Further, a positive electrode side terminal 21P and a negative electrode side terminal 21N are provided on the opposite end surface (upper end surface) of the mounting surface of the smoothing capacitor 21.

[0095] Specifically, as shown in FIGS. 2 and 3, four smoothing capacitors 21 are arranged side by side in the X-axis direction and six smoothing capacitors 21 are arranged side by side in the Y-axis direction.

[0096] On the upper end surface of the smoothing capacitor 21, a laminated bus bar 20PN is arranged substantially parallel to the X-axis direction and the Y-axis direction.

[0097] The laminated bus bar 20PN has a substantially rectangular shape when viewed from above. The laminated bus bar 20PN is arranged over a range covering 24 smoothing capacitors 21 in the X-axis direction and the Y-axis direction.

[0098] As shown in FIGS. 4 and 5, the laminated bus bar 20PN is composed of a positive electrode side bus bar 20P and a negative electrode side bus bar 20N laminated via an insulating layer 20I1. Specifically, the laminated bus bar 20PN has a four-layer laminated structure in which the negative electrode side bus bar 20N is disposed at the lowermost layer, the insulating layer 20I1 is disposed thereon, the positive electrode side bus bar 20P is disposed thereon, and the insulating layer 20I2 is disposed at the uppermost layer.

[0099] As shown in FIGS. 4 to 6, the lowermost negative electrode side bus bar 20N is provided with a relatively small through hole that is bolted to the negative electrode side terminal 21N of the smoothing capacitor 21. Thereby, the negative electrode side terminal 21N of the smoothing capacitor 21 and the negative electrode side bus bar 20N can be directly connected. Further, the negative electrode side bus bar 20N is provided with a relatively large through hole for exposing the positive electrode side terminal 21P in a top view. Thereby, the positive electrode side bus bar 20P and the positive electrode side terminal 21P in the layer above the negative electrode side bus bar 20N can be connected.

[0100] As shown in FIGS. 4 and 5, the insulating layer 20I1 adjacent to the negative electrode side bus bar 20N is provided with a relatively large through hole for exposing the positive electrode side terminal 21P and the negative electrode side terminal 21N of the smoothing capacitor 21 (i.e., the through hole for fastening the negative electrode side bus bar 20N) in a top view.

[0101] As shown in FIGS. 4 to 6, the positive electrode side bus bar 20P adjacent to the insulating layer 20I1 is provided with a relatively small through hole that is bolted to the positive electrode side terminal 21P of the smoothing capacitor 21. Thereby, the positive electrode side terminal 21P of the smoothing capacitor 21 and the positive electrode side bus bar 20P can be directly connected. Further, the positive electrode side bus bar 20P is provided with a relatively large through hole for exposing the negative electrode side terminal 21N of the smoothing capacitor 21 (i.e., the through hole for fastening the negative electrode side bus bar 20N) in a top view. Thereby, the operator can access the through hole for fastening the negative electrode side bus bar 20N in the layer below the positive electrode side bus bar 20P.

[0102] As shown in FIGS. 4 and 5, relatively large through-holes are provided in the uppermost insulating layer 20I2 to expose the positive terminal 21P of the smoothing capacitor 21 (i.e., the through-hole for fastening the positive bus bar 20P) and the negative terminal 21N (i.e., the through-hole for fastening the negative bus bar 20N) in a top view.

[0103] The positive bus bar 20P and the negative bus bar 20N of the laminated bus bar 20PN have, for example, substantially the same thickness. As a result, the current densities of the positive bus bar 20P and the negative bus bar 20N become substantially equal.

[0104] Also, the laminated bus bar 20PN may be arranged in the housing 1H such that the overlapping area of the positive bus bar 20P and the negative bus bar 20N is relatively large (preferably, maximized). Further, the thickness of the insulating layer 20I1 may be set such that the distance between the positive bus bar 20P and the negative bus bar 20N is relatively small while ensuring the insulation between the positive bus bar 20P and the negative bus bar 20N. Thereby, current paths flowing in opposite directions can be brought closer in space. Therefore, at least a part of the magnetic field generated by the current in the positive bus bar 20P and the magnetic field generated by the current in the negative bus bar 20N can be canceled out, and the inductance of the positive bus bar 20P and the negative bus bar 20N can be reduced. Also, as described above, when the current densities are substantially equal, the magnitudes of the magnetic fields generated by both the current in the positive bus bar 20P and the current in the negative bus bar 20N become substantially equal, and most of the generated magnetic fields can be canceled out. Therefore, the inductance of the positive bus bar 20P and the negative bus bar 20N can be further suppressed. Thus, with the reduction of the inductance of the positive bus bar 20P and the negative bus bar 20N, the surge voltage of the power conversion device 1 can be suppressed.

[0105] As described above, the inverter circuit 40 includes a bridge circuit composed of a U-phase circuit 41, a V-phase circuit 42, and a W-phase circuit 43.

[0106] As shown in FIGS. 2 and 3, the U-phase circuit 41, the V-phase circuit 42, and the W-phase circuit 43 are arranged in order in the Y-axis direction from the end in the negative Y-axis direction to the end in the positive Y-axis direction.

[0107] The U-phase circuit 41 includes four switch modules 410 (i.e., corresponding to the above-mentioned switch modules 411 to 414).

[0108] Two groups in which two of the four switch modules 410 are arranged side by side in the X-axis direction are arranged in two rows in the Y-axis direction. Also, the four switch modules 410 are arranged on another component placed on the bottom surface of the housing 1H (for example, the control circuit of the power conversion device 1, the drive circuits of the semiconductor switches 410s, 420s, 430s, the cooling mechanism of the inverter circuit 40, etc.). Thereby, the difference in the upper end position from the smoothing capacitor 21 having a relatively large dimension in the Z-axis direction can be made relatively small. Therefore, the positions of the positive electrode side bus bar 20P and the negative electrode side bus bar 20N in the Z-axis direction and the positions of the U-phase positive electrode side DC bus bar 41P and the U-phase negative electrode side DC bus bar 41N in the Z-axis direction can be made relatively close to each other.

[0109] As shown in FIGS. 4 and 5, the switch module 410 has a box shape, and notches for fastening and seat surfaces for bolts are provided at the corners in a top view.

[0110] The switch module 410 is arranged such that the longitudinal direction in a top view is substantially along the X-axis direction. Along the longitudinal direction (i.e., the X-axis direction) of the switch module 410, the AC output terminal 410O, the negative electrode side terminal 410N, and the positive electrode side terminal 410P are arranged in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21).

[0111] Further, a switch leg of a form different from a form in which a series connection body of two semiconductor switches 410s is accommodated in advance in a housing, such as the switch module 410, may be applied to the U-phase circuit 41. Hereinafter, the same may apply to the switch module 420 of the V-phase circuit 42 and the switch module 430 of the W-phase circuit 43, and the same may apply to the second to fourth embodiments described later.

[0112] At the upper end of the switch module 410, a U-phase laminated bus bar 41PN is arranged substantially parallel to the X-axis direction and the Y-axis direction. Specifically, the U-phase laminated bus bar 41PN is configured to be integrally connected to a V-phase laminated bus bar 42PN and a W-phase laminated bus bar 43PN, which will be described later. That is, at the upper end of the switch module 410, a laminated bus bar 40PN including a U-phase laminated bus bar 41PN, a V-phase laminated bus bar 42PN, and a W-phase laminated bus bar 43PN is arranged substantially parallel to the X-axis direction and the Y-axis direction. Hereinafter, the same applies to the second to fourth embodiments described later.

[0113] The U-phase laminated bus bar 41PN is arranged over a range covering four switch modules 410 in the X-axis direction and the Y-axis direction.

[0114] As shown in FIGS. 4 and 5, the U-phase laminated bus bar 41PN is configured by laminating a U-phase positive-side DC bus bar 41P and a U-phase negative-side DC bus bar 41N via an insulating layer 41I1. Specifically, the U-phase laminated bus bar 41PN has a four-layer laminated structure in which the U-phase negative-side DC bus bar 41N is arranged in the lowermost layer, the insulating layer 41I1 is arranged thereon, the U-phase positive-side DC bus bar 41P is arranged thereon, and the insulating layer 41I2 is arranged in the uppermost layer.

[0115] The U-phase positive-side DC bus bar 41P is configured to be integrally connected to the V-phase positive-side DC bus bar 42P and the W-phase positive-side DC bus bar 43P described later (for example, as an integral plate-like member). That is, as shown in FIG. 6, the laminated bus bar 40PN includes a positive-side DC bus bar 40P configured to include the U-phase positive-side DC bus bar 41P, the V-phase positive-side DC bus bar 42P, and the W-phase positive-side DC bus bar 43P. The same applies to the second to fourth embodiments described later.

[0116] The U-phase negative-side DC bus bar 41N is configured to be integrally connected to the V-phase negative-side DC bus bar 42N and the W-phase negative-side DC bus bar 43N described later (for example, as an integral plate-like member). That is, as shown in FIG. 6, the laminated bus bar 40PN includes a negative-side DC bus bar 40N configured to include the U-phase negative-side DC bus bar 41N, the V-phase negative-side DC bus bar 42N, and the W-phase negative-side DC bus bar 43N. The same applies to the second to fourth embodiments described later.

[0117] The insulating layer 41I1 may be configured to be integrally connected to the insulating layer 42I1 and the insulating layer 43I1 described later (for example, as an integral plate-like member). Similarly, the insulating layer 42I2 may be configured to be integrally connected to the insulating layer 42I2 and the insulating layer 43I2 described later (for example, as an integral plate-like member). The same may apply to the second to fourth embodiments described later.

[0118] As shown in FIGS. 4 to 6, the lowermost U-phase negative-side DC bus bar 41N is provided with a relatively small through hole that is bolted to the negative-side terminal 410N of the switch module 410. Thereby, the negative-side terminal 410N of the switch module 410 and the U-phase negative-side DC bus bar 41N can be directly connected. Further, the U-phase negative-side DC bus bar 41N is provided with a relatively large substantially rectangular through hole for exposing the positive-side terminal 410P in a top view. Thereby, the U-phase positive-side DC bus bar 41P and the positive-side terminal 410P in a layer above the U-phase negative-side DC bus bar 41N can be connected. Further, the U-phase negative-side DC bus bar 41N is provided with a relatively large substantially rectangular through hole for exposing the AC output terminal 410O in a top view. Thereby, the U-phase AC bus bar 41O and the AC output terminal 410O above the U-phase negative-side DC bus bar 41N can be connected.

[0119] As shown in FIGS. 4 and 5, the insulating layer 41I1 adjacent to the upper side of the U-phase negative-side DC bus bar 41N is provided with a relatively large substantially rectangular through hole corresponding to the switch module 410. Thereby, the positive-side terminal 410P, the negative-side terminal 410N (i.e., the through hole for fastening the U-phase negative-side DC bus bar 41N), and the AC output terminal 410O can be exposed in a top view.

[0120] As shown in FIGS. 4 to 6, the U-phase positive-side DC bus bar 41P adjacent to the upper side of the insulating layer 41I1 is provided with a relatively small through hole that is bolted to the positive-side terminal 410P of the switch module 410. Thereby, the positive-side terminal 410P of the switch module 410 and the U-phase positive-side DC bus bar 41P can be directly connected. Further, the U-phase positive-side DC bus bar 41P is provided with a relatively large through hole for exposing the negative-side terminal 410N of the switch module 410 (i.e., the through hole for fastening the U-phase negative-side DC bus bar 41N) and the AC output terminal 410O in a top view. Thereby, an operator can access the through hole for fastening the U-phase negative-side DC bus bar 41N and the AC output terminal 410O in a layer below the U-phase positive-side DC bus bar 41P.

[0121] As shown in FIGS. 4 and 5, a relatively large rectangular through-hole corresponding to the switch module 410 is provided in the uppermost insulating layer 41I2. Thereby, the positive terminal 410P of the switch module 410 (i.e., the through-hole for fastening the U-phase positive DC busbar 41P), the negative terminal 410N (i.e., the through-hole for fastening the U-phase negative DC busbar 41N), and the AC output terminal 410O can be exposed in a top view.

[0122] The U-phase positive DC busbar 41P and the U-phase negative DC busbar 41N of the U-phase laminated busbar 41PN have, for example, substantially the same thickness. Thereby, the current densities of the U-phase positive DC busbar 41P and the U-phase negative DC busbar 41N become substantially equal.

[0123] As shown in FIGS. 2 to 6, the U-phase AC busbar 41O connects between the AC output terminal 410O of the switch module 410 and the U-phase output terminal 41T. The U-phase AC busbar 41O includes a U-phase parallel connection busbar 41O1 and a U-phase output busbar 41O2.

[0124] The U-phase parallel connection busbar 41O1 is a component for parallely connecting the AC output terminals 410O of the four switch modules 410 in the overall configuration of the U-phase AC busbar 41O. Specifically, the U-phase parallel connection busbar 41O1 is a component for merging the power paths from the respective AC output terminals 410O of the four switch modules 410 to the U-phase output terminal 41T in the overall configuration of the U-phase AC busbar 41O.

[0125] As shown in FIGS. 2 and 3, the bus bar 41O1 for U-phase parallel connection is configured to be plane-symmetric with respect to the vertical plane with respect to the X-axis at the central position between two switch modules 410 arranged in the X-axis direction. Further, the bus bar 41O1 for U-phase parallel connection is configured to be plane-symmetric with respect to the vertical plane with respect to the Y-axis at the central position between two rows of switch modules 410 arranged in the Y-axis direction. And the bus bar 41O1 for U-phase parallel connection is connected to the bus bar 41O2 for U-phase output at a portion corresponding to the central position of the AC output terminals 410O of the four switch modules 410 in the X-axis direction and the Y-axis direction. Thereby, the path lengths until the paths from the respective AC output terminals 410O of the four switch modules 410 merge toward the U-phase output terminal 41T can be made substantially equal. Also, the current density for each path from the respective AC output terminals 410O of the four switch modules 410 toward the U-phase output terminal 41T can be made substantially equal. Therefore, the inductance of the power path between the four switch modules 410 and the U-phase output terminal 41T can be made substantially equal.

[0126] Specifically, the bus bar 41O1 for U-phase parallel connection includes two leg portions 41O1a and a connecting portion 41O1b.

[0127] The two legs 41O1a each have a flat plate shape that is substantially parallel to the X-axis direction and the Z-axis direction. The two legs 41O1a are each provided in two rows in the Y-axis direction and connect the AC output terminals 410O of the two switch modules 410 arranged in the X-axis direction. The two legs 41O1a are configured to be symmetric with respect to a vertical plane in the X-axis direction at a substantially central position between the AC output terminals 410O of the two switch modules 410 arranged in the X-axis direction. Specifically, the leg 41O1a includes two seat surfaces, two lower legs, an intermediate leg, and an upper leg. The two seat surfaces have a substantially rectangular shape in top view and are placed on the AC output terminals 410O of the two switch modules 410 arranged in the X-axis direction, respectively, and have fastening holes for bolt fastening with the AC output terminals 410O. The two lower legs are provided so as to extend upward from each of the two seat surfaces. The intermediate leg connects the two lower legs so as to extend in the X-axis direction. The upper leg is provided so as to extend upward from the upper end of the intermediate leg and the central portion in the X-axis direction. Thereby, the leg 41O1a can merge the paths from the respective AC output terminals 410O of the two switch modules 410 at substantially the same distance. Also, the leg 41O1a can make the cross-sectional areas of the paths from the respective AC output terminals 410O of the two switch modules 410 substantially the same and make the current density substantially the same. Further, the two legs 41O1a are configured to be symmetric with respect to a vertical plane in the Y-axis direction at a substantially central position between the AC output terminals 410O of the two switch modules 410 arranged in the Y-axis direction. Thereby, the two legs 41O1a can make the paths from the two switch modules 410 to the merge point substantially the same distance from each other.

[0128] The connecting part 41O1b has a flat plate shape that is substantially parallel to the X-axis direction and the Y-axis direction, and connects two leg parts 41O1a arranged side by side in the Y-axis direction. Specifically, in a top view, the connecting part 41O1b has a substantially rectangular shape and connects the upper leg parts of the two leg parts 41O1a so as to extend in the Y-axis direction. Also, the connecting part 41O1b is configured to be plane-symmetric with respect to a vertical plane with respect to the Y-axis at a substantially central position between the two leg parts 41O1a in the Y-axis direction, that is, at a substantially central position between the AC output terminals 410O of two (two rows) switch modules 410 arranged side by side in the Y-axis direction. Further, the connecting part 41O1b is connected to the U-phase output bus bar 41O2 at a substantially central position between the two leg parts 41O1a in the Y-axis direction. Thereby, the U-phase parallel connection bus bar 41O1 can make the lengths of all paths substantially equal while merging two paths from four switch modules 410 at equal lengths, and can make the current density for each path the same.

[0129] The U-phase output bus bar 41O2 is provided so as to extend from the central part in the Y-axis direction of the connecting part 41O1b of the U-phase parallel connection bus bar 41O1 toward the negative X-axis direction in a top view, and is connected to the U-phase output terminal 41T.

[0130] The V-phase circuit 42 includes four switch modules 420, similar to the U-phase circuit 41.

[0131] Since the arrangement structure of the four switch modules 420 is the same as that of the four switch modules 410 of the U-phase circuit 41, the description thereof is omitted.

[0132] As shown in FIGS. 4 and 5, the external shape of the switch module 420 is the same as that of the switch module 410.

[0133] The switch module 420 is arranged such that the longitudinal direction in a top view substantially follows the X-axis direction. Along the longitudinal direction (that is, the X-axis direction) of the switch module 420, the AC output terminal 420O, the negative electrode side terminal 420N, and the positive electrode side terminal 420P are arranged side by side in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21).

[0134] At the upper end of the switch module 420, the V-phase laminated busbar 42PN is arranged substantially parallel to the X-axis direction and the Y-axis direction.

[0135] The V-phase laminated busbar 42PN is arranged over a range covering four switch modules 420 in the X-axis direction and the Y-axis direction.

[0136] As shown in FIGS. 4 and 5, the V-phase laminated busbar 42PN is formed by laminating a V-phase positive-side DC busbar 42P and a V-phase negative-side DC busbar 42N via an insulating layer 42I1. Specifically, the V-phase laminated busbar 42PN has a four-layer laminate structure in which the V-phase negative-side DC busbar 42N is arranged in the lowermost layer, the insulating layer 42I1 is arranged thereon, the V-phase positive-side DC busbar 42P is arranged thereon, and the insulating layer 42I2 is arranged in the uppermost layer.

[0137] The V-phase positive-side DC busbar 42P is configured to be integrally connected with the U-phase positive-side DC busbar 41P and the W-phase positive-side DC busbar 43P to be described later as described above.

[0138] The V-phase negative-side DC busbar 42N is configured to be integrally connected with the U-phase negative-side DC busbar 41N and the W-phase negative-side DC busbar 43N to be described later as described above.

[0139] The insulating layer 42I1 may be configured to be integrally connected with the insulating layer 41I1 and the insulating layer 43I1 to be described later as described above. Similarly, the insulating layer 42I2 may be configured to be integrally connected with the insulating layer 41I2 and the insulating layer 43I2 to be described later as described above.

[0140] Since the detailed structure of the V-phase laminated busbar 42PN is the same as that of the U-phase laminated busbar 41PN, the description thereof is omitted.

[0141] As shown in FIGS. 2 to 6, the V-phase AC bus bar 42O is connected between the AC output terminal 420O of the switch module 420 and the V-phase output terminal 42T. The V-phase AC bus bar 42O includes a V-phase parallel connection bus bar 42O1 and a V-phase output bus bar 42O2.

[0142] Since the arrangement and structure of the V-phase AC bus bar 42O are the same as those of the U-phase AC bus bar 41O, the description thereof is omitted.

[0143] The W-phase circuit 43 includes four switch modules 430, similar to the U-phase circuit 41.

[0144] Since the arrangement structure of the four switch modules 430 is the same as that of the four switch modules 410 of the U-phase circuit 41, the description thereof is omitted.

[0145] As shown in FIGS. 4 and 5, the external shape of the switch module 430 is the same as that of the switch module 410.

[0146] The switch module 430 is arranged such that the longitudinal direction in the top view is substantially along the X-axis direction. Along the longitudinal direction (i.e., the X-axis direction) of the switch module 430, the AC output terminal 430O, the negative terminal 430N, and the positive terminal 430P are arranged in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21).

[0147] At the upper end of the switch module 430, the W-phase laminated bus bar 43PN is arranged substantially parallel to the X-axis direction and the Y-axis direction.

[0148] The W-phase laminated bus bar 43PN is arranged over a range covering the four switch modules 430 in the X-axis direction and the Y-axis direction.

[0149] As shown in FIGS. 4 and 5, the W-phase laminated busbar 43PN is formed by laminating the W-phase positive-side DC busbar 43P and the W-phase negative-side DC busbar 43N via an insulating layer 43I1. Specifically, the W-phase laminated busbar 43PN has a four-layer laminated structure in which the W-phase negative-side DC busbar 43N is disposed at the lowermost layer, the insulating layer 43I1 is disposed thereon, the W-phase positive-side DC busbar 43P is disposed thereon, and the insulating layer 43I2 is disposed at the uppermost layer.

[0150] As described above, the W-phase positive-side DC busbar 43P is configured to be integrally connected with the U-phase positive-side DC busbar 41P and the V-phase positive-side DC busbar 42P.

[0151] As described above, the W-phase negative-side DC busbar 43N is configured to be integrally connected with the U-phase negative-side DC busbar 41N and the V-phase negative-side DC busbar 42N.

[0152] As described above, the insulating layer 43I1 may be configured to be integrally connected with the insulating layer 41I1 and the insulating layer 42I1. Similarly, the insulating layer 43I2 may be configured to be integrally connected with the insulating layer 41I2 and the insulating layer 42I2.

[0153] Since the detailed structure of the W-phase laminated busbar 43PN is the same as that of the U-phase laminated busbar 41PN, the description thereof is omitted.

[0154] As shown in FIGS. 2 to 6, the W-phase AC busbar 43O connects between the AC output terminal 430O of the switch module 430 and the W-phase output terminal 43T. The W-phase AC busbar 43O includes a W-phase parallel connection busbar 43O1 and a W-phase output busbar 43O2.

[0155] Since the arrangement and structure of the W-phase AC busbar 43O are the same as those of the U-phase AC busbar 41O, the description thereof is omitted.

[0156] The laminated bus bar 40PN may be disposed in the housing 1H such that the overlapping area of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N is relatively large (preferably, maximized). Further, the thicknesses of the insulating layers 41I1, 42I1, 43I1 may be set such that the distance between the positive-side DC bus bar 40P and the negative-side DC bus bar 40N is relatively small while ensuring the insulation between them. Thereby, current paths flowing in opposite directions can be brought close to each other in space. Therefore, at least a part of the magnetic field generated by the current in the positive-side DC bus bar 40P and the magnetic field generated by the current in the negative-side DC bus bar 40N can be canceled out. For example, when a current of phase U flows through the positive-side DC bus bar 40P, a current of phase V or phase W flows through the negative-side DC bus bar 40N. Thus, the inductances of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N can be reduced. Also, as described above, when the current densities are substantially equal, the magnitudes of the magnetic fields generated by both the current in the positive-side DC bus bar 40P and the current in the negative-side DC bus bar 40N become substantially equal, and most of the generated magnetic fields can be canceled out. Therefore, the inductances of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N can be further suppressed. Thus, the surge voltage of the power conversion device 1 can be suppressed as the inductances of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N are reduced.

[0157] As described above, in the first embodiment, the positive-side bus bar 20P and the negative-side bus bar 20N of the smoothing circuit 20 have a laminated structure laminated via the insulating layer 20I1. Similarly, the positive-side DC bus bar 40P and the negative-side DC bus bar 40N of the inverter circuit 40 have a laminated structure laminated via the insulating layers 41I1, 42I1, 43I1. Thereby, the inductance of the DC portion of the one-way power path between the smoothing circuit 20 and the output terminal 40T can be reduced and made very small. Therefore, the surge voltage associated with the ON / OFF of the semiconductor switches 410s, 420s, 430s of the power conversion device 1 can be suppressed.

[0158] Also, in the first embodiment, the U-phase parallel connection bus bar 41O1 is configured such that the lengths of the power paths from the AC output terminals 410O of the four switch modules 410 to the point where they merge toward the U-phase output terminal 41T are substantially equal. Specifically, the U-phase parallel connection bus bar 41O1 is configured such that the lengths of the power paths between the connection parts of the four switch modules 410 (AC output terminals 410O thereof) and the U-phase output bus bar 41O2 are substantially equal. Thereby, the difference in inductance of each power path between the AC output terminal 410O of the four switch modules 410 and the U-phase output terminal 41T can be relatively reduced. Therefore, the difference in inductance of each one-round power path passing through the four switch modules 410 between the smoothing circuit 20 and the U-phase output terminal 41T can be relatively reduced. Also, the U-phase parallel connection bus bar 41O1 is configured such that the current density of each power path from the AC output terminal 410O of the four switch modules 410 to the point where they merge toward the U-phase output terminal 41T is substantially equal. Thereby, the inductances of all the power paths between the AC output terminal 410O of the four switch modules 410 and the U-phase output terminal 41T can be made substantially equal. Therefore, the inductances of each one-round power path passing through the four switch modules 410 between the smoothing circuit 20 and the U-phase output terminal 41T can be made substantially equal. Similarly, the V-phase parallel connection bus bar 42O1 is configured such that the lengths of the power paths from the AC output terminals 420O of the four switch modules 420 to the point where they merge toward the V-phase output terminal 42T are substantially equal. Thereby, the difference in inductance of each power path between the AC output terminal 420O of the four switch modules 420 and the V-phase output terminal 42T can be relatively reduced. Therefore, the difference in inductance of each one-round power path passing through the four switch modules 420 between the smoothing circuit 20 and the V-phase output terminal 42T can be relatively reduced. Also, the V-phase parallel connection bus bar 42O1 is configured such that the current density of each power path from the AC output terminal 420O of the four switch modules 420 to the point where they merge toward the V-phase output terminal 42T is substantially equal.As a result, the inductances of all the power paths between the AC output terminals 420O and the V-phase output terminals 42T of the four switch modules 420 can be made substantially equal. Therefore, the inductances of the power paths for one round passing through the four switch modules 420 between the smoothing circuit 20 and the V-phase output terminals 42T can be made substantially equal. Similarly, the W-phase parallel connection busbar 43O1 is configured such that the lengths of the power paths from the respective AC output terminals 430O of the four switch modules 430 to the point of confluence toward the W-phase output terminals 43T are substantially equal. As a result, the difference in the inductances of the respective power paths between the AC output terminals 430O and the W-phase output terminals 43T of the four switch modules 430 can be made relatively small. Therefore, the difference in the inductances of the power paths for one round passing through the four switch modules 430 between the smoothing circuit 20 and the W-phase output terminals 43T can be made relatively small. Also, the W-phase parallel connection busbar 43O1 is configured such that the current density for each power path from the respective AC output terminals 430O of the four switch modules 430 to the point of confluence toward the W-phase output terminals 43T is substantially equal. As a result, the inductances of all the power paths between the AC output terminals 430O and the W-phase output terminals 43T of the four switch modules 430 can be made substantially equal. Therefore, the inductances of the power paths for one round passing through the four switch modules 430 between the smoothing circuit 20 and the W-phase output terminals 43T can be made substantially equal. As described above, this is because the inductance of the DC portion in the power path for one round between the smoothing circuit 20 and the output terminals 40T is very small, and the inductance of the AC portion is dominant. Thus, the current imbalance of each of the four switch modules 410, the four switch modules 420, and the four switch modules 430 can be suppressed, and current uniformity can be achieved.

[0159] In the first embodiment, the number of switch modules 410 connected in parallel may be arbitrary as long as the lengths of all power paths from the AC output terminals 410O of the respective switch modules 410 to the U-phase output terminal 41T are substantially equal. That is, the number of switch modules 410 connected in parallel may be two or three, or may be five or more. For example, when the number of switch modules 410 connected in parallel is two, the U-phase parallel connection busbar 41O1 may be composed of only the leg portion 41O1a and may be connected to the U-phase output busbar 41O2 at a substantially central position (midpoint) in the X-axis direction at the upper end of the leg portion 41O1a. The same may apply to the number of switch modules 420 and switch modules 430. In the first embodiment, the plurality of switch modules 410 may be arbitrarily arranged as long as the lengths of all power paths from the AC output terminals 410O of the respective switch modules 410 to the U-phase output terminal 41T are substantially equal. For example, three or more of the plurality of switch modules 410 may be arranged in the X-axis direction. Also, for example, the plurality of switch modules 410 may be arranged in a row in the X-axis direction, or the rows in the X-axis direction may be arranged in three or more columns in the Y-axis direction. For example, the number arranged in each of the X-axis direction and the Y-axis direction is preferably a power of two. Thereby, as described above, while merging two paths from each AC output terminal 410O of the plurality of switch modules 410 with equal length, the lengths of all paths and the current density for each path can be made substantially the same. The same may apply to the arrangement of the switch modules 420 and the switch modules 430. In the first embodiment, the configuration of the U-phase parallel connection busbar 41O1 may be arbitrary as long as the lengths of all power paths from the AC output terminals 410O of the respective switch modules 410 to the U-phase output terminal 41T are substantially equal. For example, as long as the lengths of all power paths from the AC output terminals 410O of the four switch modules 410 to the U-phase output terminal 41T are substantially equal, the U-phase parallel connection busbar 41O1 does not have to have the above-described plane-symmetrical configuration.Specifically, the two leg portions 41O1a of the bus bar 41O1 for U-phase parallel connection may be configured in substantially the same shape spaced apart from each other in the Y-axis direction, rather than in a plane-symmetric shape with respect to a plane perpendicular to the Y-axis direction. The same may apply to the configurations of the bus bar 42O1 for V-phase parallel connection and the bus bar 43O1 for W-phase parallel connection.

[0160] [Second Embodiment] Next, with reference to FIGS. 7 to 10, the second embodiment will be described. Hereinafter, the description will focus on the parts different from the power conversion device 1 according to the first embodiment, and the description of the same or corresponding content as that of the first embodiment may be simplified or omitted.

[0161] <Overview of Power Conversion Device> FIG. 7 is a circuit diagram showing an example of the power conversion device 1 according to the second embodiment.

[0162] As shown in FIG. 7, the power conversion device 1 includes a rectifier circuit 10, a smoothing circuit 20, a fuse 30, and an inverter circuit 40, similar to the case of the first embodiment.

[0163] The inverter circuit 40 includes a bridge circuit composed of a U-phase circuit 41, a V-phase circuit 42, and a W-phase circuit 43, similar to the case of the first embodiment.

[0164] The U-phase circuit 41 includes a U-phase positive-side DC bus bar 41P, a U-phase negative-side DC bus bar 41N, switch modules 411 to 414, and a U-phase AC bus bar 41O, similar to the first embodiment. Further, different from the case of the first embodiment, the U-phase circuit 41 further includes switch modules 415 and 416. Hereinafter, in the second embodiment, as well as in the third and fourth embodiments described later, the switch modules 411 to 416 may be collectively referred to as, or any one of the switch modules 411 to 416 may be individually referred to as, "switch module 410". That is, different from the case of the first embodiment, the U-phase circuit 41 includes six switch modules 410.

[0165] Switch modules 411 to 416 (an example of a switch leg) are connected in parallel between the U-phase positive-side DC bus bar 41P and the U-phase negative-side DC bus bar 41N.

[0166] Switch module 415 includes semiconductor switches 415s1 and 415s2 corresponding to the upper and lower arms, freewheeling diodes 415d1 and 415d2, a positive-side terminal 415P, a negative-side terminal 415N, and an AC output terminal 415O.

[0167] Switch module 416 includes semiconductor switches 416s1 and 416s2 corresponding to the upper and lower arms, freewheeling diodes 416d1 and 416d2, a positive-side terminal 416P, a negative-side terminal 416N, and an AC output terminal 416O.

[0168] Hereinafter, in the second embodiment, as well as in the third and fourth embodiments described later, the semiconductor switches 411s1, 411s2, 412s1, 412s2, 413s1, 413s2, 414s1, 414s2, 415s1, 415s2, 416s1, 416s2 may be collectively referred to as "semiconductor switch 410s", or any one of them may be individually referred to as such. Also, in the second embodiment, as well as in the third and fourth embodiments described later, the components corresponding to the positive-side terminals 411P to 416P of the above-mentioned "switch module 410" may be referred to as "positive-side terminal 410P". Also, in the second embodiment, as well as in the third and fourth embodiments described later, the components corresponding to the negative-side terminals 411N to 416N of the above-mentioned "switch module 410" may be referred to as "negative-side terminal 410N". Also, in the second embodiment, as well as in the third and fourth embodiments described later, the components corresponding to the AC output terminals 411O to 416O of the above-mentioned "switch module 410" may be referred to as "AC output terminal 410O".

[0169] Switch modules 411 to 416 have the same components and are configured by the same circuit.

[0170] The U-phase AC busbar 41O is connected to each of the AC output terminals 411O to 416O of the switch modules 411 to 416 at one end, and is connected to the U-phase output terminal 41T at the other end. Thereby, the inverter circuit 40 can output the U-phase AC power output from the switch modules 411 to 416 to the outside from the U-phase output terminal 41T.

[0171] Similar to the first embodiment, the V-phase circuit 42 includes a V-phase positive-side DC busbar 42P, a V-phase negative-side DC busbar 42N, switch modules 421 to 424, and a V-phase AC busbar 42O. Also, different from the case of the first embodiment, the V-phase circuit 42 further includes switch modules 425 and 426. Hereinafter, in the second embodiment and the third and fourth embodiments described later, the switch modules 421 to 426 may be collectively referred to as, or any one of the switch modules 421 to 426 may be individually referred to as, "switch module 420". That is, different from the case of the first embodiment, the V-phase circuit 42 includes six switch modules 420.

[0172] The switch modules 421 to 426 are connected in parallel between the V-phase positive-side DC busbar 42P and the V-phase negative-side DC busbar 42N.

[0173] The switch module 425 includes semiconductor switches 425s1 and 425s2 corresponding to the upper and lower arms, circulation diodes 425d1 and 425d2, a positive-side terminal 425P, a negative-side terminal 425N, and an AC output terminal 425O.

[0174] The switch module 426 includes semiconductor switches 426s1 and 426s2 corresponding to the upper and lower arms, circulation diodes 426d1 and 426d2, a positive-side terminal 426P, a negative-side terminal 426N, and an AC output terminal 426O.

[0175] In the following, in the second embodiment, as well as the third and fourth embodiments described later, the semiconductor switches 421s1, 421s2, 422s1, 422s2, 423s1, 423s2, 424s1, 424s2, 425s1, 425s2, 426s1, 426s2 may be collectively referred to as "semiconductor switch 420s", or any one of them may be individually referred to as such. Also, in the second embodiment, as well as the third and fourth embodiments described later, the components corresponding to the positive terminal 421P to 426P of the above-mentioned "switch module 420" may be referred to as "positive terminal 420P". Further, in the second embodiment, as well as the third and fourth embodiments described later, the components corresponding to the negative terminal 421N to 426N of the above-mentioned "switch module 420" may be referred to as "negative terminal 420N". Moreover, in the second embodiment, as well as the third and fourth embodiments described later, the components corresponding to the AC output terminals 421O to 426O of the above-mentioned "switch module 420" may be referred to as "AC output terminal 420O".

[0176] The switch modules 421 to 426 have the same components and are composed of the same circuits.

[0177] The V-phase AC busbar 42O is connected at one end to connect the respective AC output terminals 421O to 426O of the switch modules 421 to 426 to each other, and is connected at the other end to the V-phase output terminal 42T. Thereby, the inverter circuit 40 can output the V-phase AC power output from the switch modules 421 to 426 to the outside from the V-phase output terminal 42T.

[0178] The W-phase circuit 43 includes a W-phase positive-side DC busbar 43P, a W-phase negative-side DC busbar 43N, switch modules 431 to 434, and a W-phase AC busbar 43O, similar to the first embodiment. Also, different from the case of the first embodiment, the W-phase circuit 43 further includes switch modules 435 and 436. Hereinafter, in the second embodiment and the third and fourth embodiments described later, the switch modules 431 to 436 may be collectively or any one of the switch modules 431 to 436 may be individually referred to as the "switch module 430". That is, different from the case of the first embodiment, the W-phase circuit 43 includes six switch modules 430.

[0179] The switch modules 431 to 436 are connected in parallel between the W-phase positive-side DC busbar 43P and the W-phase negative-side DC busbar 43N.

[0180] The switch module 435 includes semiconductor switches 435s1 and 435s2 corresponding to the upper and lower arms, freewheeling diodes 435d1 and 435d2, a positive-side terminal 435P, a negative-side terminal 435N, and an AC output terminal 435O.

[0181] The switch module 436 includes semiconductor switches 436s1 and 436s2 corresponding to the upper and lower arms, freewheeling diodes 436d1 and 436d2, a positive-side terminal 436P, a negative-side terminal 436N, and an AC output terminal 436O.

[0182] In the following, in the second embodiment, as well as the third and fourth embodiments described later, the semiconductor switches 431s1, 431s2, 432s1, 432s2, 433s1, 433s2, 434s1, 434s2, 435s1, 435s2, 436s1, 436s2 may be collectively referred to as "semiconductor switch 430s", or any one of them may be individually referred to as such. Also, in the second embodiment, as well as the third and fourth embodiments described later, the components corresponding to the positive terminal 431P to 436P of the above-mentioned "switch module 430" may be referred to as "positive terminal 430P". Further, in the second embodiment, as well as the third and fourth embodiments described later, the components corresponding to the negative terminal 431N to 436N of the above-mentioned "switch module 430" may be referred to as "negative terminal 430N". Moreover, in the second embodiment, as well as the third and fourth embodiments described later, the components corresponding to the AC output terminals 431O to 436O of the above-mentioned "switch module 430" may be referred to as "AC output terminal 430O".

[0183] The switch modules 431 to 436 have the same components and are configured by the same circuit.

[0184] The W-phase AC busbar 43O is connected at one end to connect the respective AC output terminals 431O to 436O of the switch modules 431 to 436, and at the other end to the W-phase output terminal 43T. Thereby, the inverter circuit 40 can output the W-phase AC power output from the switch modules 431 to 436 to the outside from the W-phase output terminal 43T.

[0185] <Structure of the power conversion device> Figures 8 and 9 are structural diagrams showing an example of a power conversion device according to the second embodiment. Specifically, FIG. 8 is a perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed. FIG. 9 is an exploded perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed, and the output terminal 40T and the U-phase AC bus bar 41O, V-phase AC bus bar 42O, and W-phase AC bus bar 43O are removed and moved upward. FIG. 10 is a diagram for explaining the current path flowing through each switch module 410 arranged side by side in the X-axis direction. In FIG. 10, the current paths passing through the three switch modules 410 arranged in the X-axis direction are represented by white arrows, hatched arrows, and black arrows in order from the switch module 410 closest to the smoothing circuit 20.

[0186] As shown in FIGS. 8 and 9, the smoothing circuit 20, the fuse 30, and the inverter circuit 40 are arranged in order from one end to the other end in the longitudinal direction (i.e., in the positive X-axis direction) inside the housing 1H, in the same manner as in the first embodiment.

[0187] Also, the output terminal 40T is arranged at the central part in the longitudinal direction (X-axis direction) inside the housing 1H and at the upper part inside the housing 1H, in the same manner as in the first embodiment. Specifically, the output terminal 40T is arranged above the smoothing circuit 20 and the fuse 30 inside the housing 1H.

[0188] The output terminal 40T includes a U-phase output terminal 41T, a V-phase output terminal 42T, and a W-phase output terminal 43T as described above. The U-phase output terminal 41T, the V-phase output terminal 42T, and the W-phase output terminal 43T are arranged in order from one end to the central part in the short side direction (i.e., in the positive Y-axis direction) inside the housing 1H, in the same manner as in the first embodiment.

[0189] The inverter circuit 40 includes a bridge circuit composed of a U-phase circuit 41, a V-phase circuit 42, and a W-phase circuit 43 as described above.

[0190] As shown in FIGS. 8 and 9, the U-phase circuit 41, the V-phase circuit 42, and the W-phase circuit 43 are arranged in order in the Y-axis direction from the end in the negative Y-axis direction to the end in the positive Y-axis direction, similar to the case of the first embodiment.

[0191] The U-phase circuit 41 includes six switch modules 410 (i.e., corresponding to the above-described switch modules 411 to 416).

[0192] The six switch modules 410 are arranged in two groups of three arranged at equal intervals in the X-axis direction, and are arranged in two rows in the Y-axis direction. Also, the six switch modules 410 are arranged on another component placed on the bottom surface of the housing 1H, similar to the case of the first embodiment.

[0193] The switch module 410 is arranged such that the longitudinal direction in the top view is substantially along the X-axis direction, similar to the case of the first embodiment. On the switch module 410, along its longitudinal direction (i.e., the X-axis direction), an AC output terminal 410O, a negative electrode side terminal 410N, and a positive electrode side terminal 410P are arranged in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21).

[0194] As shown in FIGS. 8 and 9, at the upper end of the switch module 410, a U-phase laminated bus bar 41PN is arranged substantially parallel to the X-axis direction and the Y-axis direction, similar to the case of the first embodiment.

[0195] The U-phase laminated bus bar 41PN is arranged over a range covering the six switch modules 410 in the X-axis direction and the Y-axis direction.

[0196] As shown in FIGS. 8 and 9, the U-phase AC bus bar 41O connects between the AC output terminal 410O of the switch module 410 and the U-phase output terminal 41T. The U-phase AC bus bar 41O includes a U-phase parallel connection bus bar 41O1 and a U-phase output bus bar 41O2, similar to the case of the first embodiment.

[0197] As shown in FIGS. 8 and 9, the U-phase parallel connection bus bar 41O1 is connected to the U-phase output bus bar 41O2 in the vicinity of the switch module 410 that is farthest from the smoothing circuit 20 among the six switch modules 410 in a top view. Specifically, the U-phase parallel connection bus bar 41O1 is connected to the U-phase output bus bar 41O2 at a position farther from the smoothing circuit 20 in the X-axis direction than the switch module 410 at the end away from the smoothing circuit 20 in the group of three switch modules 410 arranged in two rows in the Y-axis direction and arranged in the X-axis direction in a top view.

[0198] More specifically, the U-phase parallel connection bus bar 41O1 includes six leg portions 41O1a and a connecting portion 41O1b.

[0199] Each of the six leg portions 41O1a has a flat plate shape that is substantially parallel to the X-axis direction and the Z-axis direction. Each of the six leg portions 41O1a has a seating surface portion that is placed on the AC output terminal 410O of the six switch modules 410 and a main leg portion that extends upward (in the positive Z-axis direction) from the seating surface portion. Also, the dimensions of each of the six leg portions 41O1a in the Z-axis direction are set to be substantially the same. Also, the cross-sectional area of each of the six leg portions 41O1a is set to be substantially the same. Thereby, the current density of each of the six leg portions 41O1a can be made substantially equal.

[0200] The connecting portion 41O1b has a flat plate shape that is substantially parallel to the X-axis direction and the Y-axis direction and connects the six leg portions 41O1a. Specifically, the connecting portion 41O1b has a substantially rectangular shape in a top view and is provided so as to extend in the X-axis direction and the Y-axis direction over the range where the six leg portions 41O1a are arranged. The end portion of the connecting portion 41O1b in the positive X-axis direction is provided at a position farther in the positive X-axis direction than the AC output terminals 410O of the two switch modules 410 located at the end portion in the positive X-axis direction among the six switch modules 410 and is connected to the U-phase output bus bar 41O2.

[0201] As shown in FIG. 10, among the current paths from the DC input terminal of the U-phase circuit 41 passing through the three switch modules 410 arranged in the X-axis direction until reaching the connection part between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2, the lengths of the paths flowing in the Z-axis direction are all substantially equal. This is because, as described above, the dimensions of the six leg parts 41O1a in the Z-axis direction are substantially the same. Also, among the current paths from the DC input terminal of the U-phase circuit 41 passing through the three switch modules 410 arranged in the X-axis direction until reaching the connection part between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2, the lengths of the paths flowing in the X-axis direction are also all substantially equal. This is because the laminated bus bar 20PN, the U-phase laminated bus bar 41PN, and the connection part 41O1b are arranged substantially parallel in the X-axis direction and the Y-axis direction. Therefore, the overall lengths of the current paths from the DC input terminal of the U-phase circuit 41 passing through each of the three switch modules 410 arranged in the X-axis direction until reaching the connection part between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2 are all substantially equal. The same can be said for the three switch modules 410 arranged in the X-axis direction in the other row. Therefore, the overall lengths of the current paths from the smoothing circuit 20 passing through each of the six switch modules 410 until reaching the U-phase output terminal 41T are all substantially equal. Similarly, the overall lengths of the current paths from the U-phase output terminal 41T passing through each of the six switch modules 410 until reaching the smoothing circuit 20 are also all substantially equal.

[0202] Also, for each of the six power paths passing through each of the six switch modules 410, the cross-sectional area of the connection part 41O1b, that is, its width and thickness, is set so that the current density becomes substantially equal to that of the U-phase positive-side DC bus bar 41P and the U-phase negative-side DC bus bar 41N. Thereby, the lengths and current densities of the power paths between the smoothing circuit 20 and the U-phase output terminal 41T passing through each of the six switch modules 410 are all substantially equal. Therefore, the inductances of the one-round power paths between the smoothing circuit 20 and the U-phase output terminal 41T passing through each of the six switch modules 410 can all be made substantially equal and uniform.

[0203] As shown in FIGS. 8 and 9, the U-phase output bus bar 41O2 connects between the U-phase parallel connection bus bar 41O1 and the U-phase output terminal 41T. The U-phase output bus bar 41O2 has a folded-back portion that extends upward from the end of the connecting portion 41O1b of the U-phase parallel connection bus bar 41O1 in the positive X-axis direction, and a main portion that extends toward the U-phase output terminal 41T in a manner substantially parallel to the X-axis direction and the Y-axis direction from the upper end of the folded-back portion.

[0204] Similar to the U-phase circuit 41, the V-phase circuit 42 includes six switch modules 420 (corresponding to the above-described switch modules 421 to 426).

[0205] Since the arrangement structure of the six switch modules 420 is the same as that of the six switch modules 410 of the U-phase circuit 41, the description thereof is omitted.

[0206] Similar to the switch module 410, the switch module 420 is arranged such that the longitudinal direction in a top view is substantially along the X-axis direction. On the switch module 420, along its longitudinal direction (i.e., the X-axis direction), the AC output terminal 420O, the negative terminal 420N, and the positive terminal 420P are arranged in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21).

[0207] At the upper end of the switch module 420, a V-phase laminated bus bar 42PN is arranged substantially parallel to the X-axis direction and the Y-axis direction.

[0208] The V-phase laminated bus bar 42PN is arranged over a range covering the six switch modules 420 in the X-axis direction and the Y-axis direction.

[0209] As shown in FIGS. 8 and 9, the V-phase AC bus bar 42O connects between the AC output terminal 420O of the switch module 420 and the V-phase output terminal 42T. The V-phase AC bus bar 42O includes a V-phase parallel connection bus bar 42O1 and a V-phase output bus bar 42O2.

[0210] Since the arrangement and structure of the V-phase AC bus bar 42O are the same as those of the U-phase AC bus bar 41O, the description thereof will be omitted.

[0211] Similar to the U-phase circuit 41, the W-phase circuit 43 includes six switch modules 430 (corresponding to the above-described switch modules 431 to 436).

[0212] Since the arrangement structure of the six switch modules 430 is the same as that of the six switch modules 410 of the U-phase circuit 41, the description thereof will be omitted.

[0213] The switch module 430 is arranged such that the longitudinal direction in the top view is substantially along the X-axis direction. Along the longitudinal direction (i.e., the X-axis direction) of the switch module 430, an AC output terminal 430O, a negative electrode side terminal 430N, and a positive electrode side terminal 430P are arranged in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21).

[0214] At the upper end portion of the switch module 430, a W-phase laminated bus bar 43PN is arranged substantially parallel to the X-axis direction and the Y-axis direction.

[0215] The W-phase laminated bus bar 43PN is arranged over a range covering the six switch modules 430 in the X-axis direction and the Y-axis direction.

[0216] Since the detailed structure of the W-phase laminated bus bar 43PN is the same as that of the U-phase laminated bus bar 41PN, the description thereof will be omitted.

[0217] As shown in FIGS. 8 and 9, the W-phase AC bus bar 43O connects between the AC output terminal 430O of the switch module 430 and the W-phase output terminal 43T. The W-phase AC bus bar 43O includes a W-phase parallel connection bus bar 43O1 and a W-phase output bus bar 43O2.

[0218] Since the arrangement and structure of the W-phase AC bus bar 43O are the same as those of the U-phase AC bus bar 41O, the description thereof will be omitted.

[0219] Thus, in the second embodiment, the U-phase parallel connection bus bar 41O1 is configured such that the lengths of the power paths between the DC input end of the U-phase laminated bus bar 41PN, which passes through each of the six switch modules 410, and the connection part with the U-phase output bus bar 41O2 are substantially equal. Further, the U-phase parallel connection bus bar 41O1 is configured such that the current density across the entire path of each power path between the DC input end of the U-phase laminated bus bar 41PN, which passes through each of the six switch modules 410, and the connection part with the U-phase output bus bar 41O2 is substantially equal. Specifically, the six leg portions 41O1a have substantially the same length and substantially the same cross-sectional area, and are configured such that the current density of each is substantially equal. Further, the connection portion 41O1b is configured such that the current density of each power path passing through each of the six switch modules 410 is substantially equal to the current density of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N. That is, the U-phase parallel connection bus bar 41O1 is configured such that the current density of the common part of the lengths of the six power paths (i.e., the six leg portions 41O1a) is substantially equal. And the U-phase parallel connection bus bar 41O1 is configured such that the current density of the other part, i.e., the part corresponding to the difference in the lengths of the power paths (connection portion 41O1b), is substantially equal to the current density of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N for each of the six power paths. Thereby, the lengths and current densities of the round-trip power paths between the smoothing circuit 20 and the U-phase output terminal 41T passing through each of the six switch modules 410 are all substantially equal. Therefore, the inductances of the round-trip power paths between the smoothing circuit 20 and the U-phase output terminal 41T passing through each of the six switch modules 410 can be made substantially equal and uniform. Similarly, the V-phase parallel connection bus bar 42O1 is configured such that the lengths of the power paths between the DC input end of the V-phase laminated bus bar 42PN, which passes through each of the six switch modules 420, and the connection part with the V-phase output bus bar 42O2 are all substantially equal.Also, the V-phase parallel connection busbar 42O1 is configured such that the current density across the entire path of each power path between the DC input terminal of the V-phase laminated busbar 42PN, which passes through each of the six switch modules 420, and the connection part with the V-phase output busbar 42O2 is substantially equal. Therefore, the inductances of the one-round power paths between the smoothing circuit 20 and the V-phase output terminal 42T, which pass through each of the six switch modules 420, can be made substantially equal and uniform. Similarly, the W-phase parallel connection busbar 43O1 is configured such that the lengths of the power paths between the DC input terminal of the W-phase laminated busbar 43PN, which passes through each of the six switch modules 430, and the connection part with the W-phase output busbar 43O2 are all substantially equal. Also, the W-phase parallel connection busbar 43O1 is configured such that the current density across the entire path of each power path between the DC input terminal of the W-phase laminated busbar 43PN, which passes through each of the six switch modules 430, and the connection part with the W-phase output busbar 43O2 is substantially equal. Therefore, the inductances of the one-round power paths between the smoothing circuit 20 and the W-phase output terminal 43T, which pass through each of the six switch modules 430, can be made substantially equal and uniform. Thus, the current imbalance of each of the six switch modules 410, the six switch modules 420, and the six switch modules 430 can be suppressed, and current uniformity can be achieved.

[0220] Further, in the second embodiment, the number of switch modules 410 connected in parallel may be arbitrary as long as the lengths of the power paths between the DC input terminals of the U-phase laminated busbar 41PN passing through the respective switch modules 410 and the connection portions with the U-phase output busbar 41O2 are substantially equal, and the current density across the entire path for each path is equal. That is, the number of switch modules 410 connected in parallel may be two or more and five or less, or may be seven or more. The same applies to the number of switch modules 420 and switch modules 430. Further, in the second embodiment, the plurality of switch modules 410 may be arbitrarily arranged as long as the lengths of the power paths between the DC input terminals of the U-phase laminated busbar 41PN passing through the respective switch modules 410 and the connection portions with the U-phase output busbar 41O2 are substantially equal, and the current density across the entire path for each path is equal. For example, the plurality of switch modules 410 may be arranged in a row in the X-axis direction, or a group of rows arranged in the X-axis direction may be arranged in three or more rows in the Y-axis direction. The same applies to the arrangement of the switch modules 420 and switch modules 430. Further, in the second embodiment, the configuration of the U-phase parallel connection busbar 41O1 may be arbitrary as long as the lengths of the power paths between the DC input terminals of the U-phase laminated busbar 41PN passing through the respective switch modules 410 and the connection portions with the U-phase output busbar 41O2 are substantially equal, and the current density across the entire path for each path is equal. For example, only the current density for each power path of the portion between the connection portions of the U-phase parallel connection busbar 41O1 with the leg portions 41O1a at both ends in the X-axis direction at the connection portion 41O1b may be configured to be substantially equal to the U-phase positive-side DC busbar 41P and the U-phase negative-side DC busbar 41N. That is, the connection portion 41O1b of the U-phase parallel connection busbar 41O1 may be configured such that the current density for each path section until all the paths from each of at least six switch modules 410 merge is substantially equal to the U-phase positive-side DC busbar 41P and the U-phase negative-side DC busbar 41N. The same applies to the configuration of the V-phase parallel connection busbar 42O1 and the W-phase parallel connection busbar 43O1.

[0221] [Third Embodiment] Next, with reference to FIGS. 11 and 12, the third embodiment will be described. Since the circuit configuration of the power conversion device 1 according to the third embodiment is the same as that of the above-described second embodiment (FIG. 7), the description thereof will be omitted. Hereinafter, the description will focus on the parts different from the power conversion device 1 according to the first embodiment or the second embodiment, and the description of the same or corresponding contents as those of the first embodiment or the second embodiment may be simplified or omitted.

[0222] [Structure of Power Conversion Device] FIGS. 11 and 12 are structural diagrams showing an example of the power conversion device 1 according to the third embodiment. Specifically, FIG. 11 is a perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed. FIG. 12 is an exploded perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed, and the output terminal 40T and the U-phase output bus bar 41O2, the V-phase output bus bar 42O2, and the W-phase output bus bar 43O2 are removed and moved upward.

[0223] As shown in FIGS. 11 and 12, the smoothing circuit 20, the fuse 30, and the inverter circuit 40 are arranged in order from one end to the other end in the longitudinal direction (i.e., in the positive X-axis direction) inside the housing 1H, in the same manner as in the case of the first embodiment and the like.

[0224] Also, the output terminal 40T is arranged at the center in the longitudinal direction (X-axis direction) inside the housing 1H and at the upper part inside the housing 1H, in the same manner as in the case of the first embodiment and the like. Specifically, the output terminal 40T is arranged above the smoothing circuit 20 and the fuse 30 inside the housing 1H.

[0225] The output terminal 40T includes a U-phase output terminal 41T, a V-phase output terminal 42T, and a W-phase output terminal 43T as described above. The U-phase output terminal 41T, the V-phase output terminal 42T, and the W-phase output terminal 43T are arranged in order from one end to the center in the short-side direction (i.e., in the positive Y-axis direction) inside the housing 1H, in the same manner as in the case of the first embodiment and the like.

[0226] As described above, the inverter circuit 40 includes a bridge circuit composed of a U-phase circuit 41, a V-phase circuit 42, and a W-phase circuit 43.

[0227] As shown in FIGS. 11 and 12, the U-phase circuit 41, the V-phase circuit 42, and the W-phase circuit 43 are arranged in order in the Y-axis direction from the end in the negative Y-axis direction to the end in the positive Y-axis direction, similar to the case of the first embodiment and the like.

[0228] Similar to the case of the second embodiment, the U-phase circuit 41 includes six switch modules 410 (i.e., corresponding to the above-described switch modules 411 to 416).

[0229] Similar to the case of the second embodiment, the six switch modules 410 are arranged in two groups of three arranged at equal intervals in the X-axis direction, and are arranged in two rows in the Y-axis direction. Also, similar to the case of the first embodiment and the like, the six switch modules 410 are arranged on another component placed on the bottom surface of the housing 1H.

[0230] Similar to the case of the first embodiment and the like, the switch module 410 is arranged such that the longitudinal direction in top view is substantially along the X-axis direction. On the switch module 410, along its longitudinal direction (i.e., the X-axis direction), an AC output terminal 410O, a negative electrode side terminal 410N, and a positive electrode side terminal 410P are arranged in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21).

[0231] As shown in FIG. 12, at the upper end of the switch module 410, similar to the case of the first embodiment and the like, a U-phase laminated bus bar 41PN is arranged substantially parallel to the X-axis direction and the Y-axis direction.

[0232] The U-phase laminated bus bar 41PN is arranged over a range covering the six switch modules 410 in the X-axis direction and the Y-axis direction.

[0233] As shown in FIG. 12, the U-phase AC busbar 41O is connected between the AC output terminal 410O and the U-phase output terminal 41T of the switch module 410. Similar to the case of the first embodiment and the like, the U-phase AC busbar 41O includes a U-phase parallel connection busbar 41O1 and a U-phase output busbar 41O2.

[0234] The U-phase parallel connection busbar 41O1 has a flat plate shape that is substantially parallel to the X-axis direction and the Y-axis direction, and has a substantially rectangular shape that extends over a range covering six switch modules 410 in a top view. The U-phase parallel connection busbar 41O1 is further laminated on the uppermost insulating layer 41I2 (see FIG. 4) of the U-phase laminated busbar 41PN. Thereby, the U-phase negative-side DC busbar 41N, the U-phase positive-side DC busbar 41P, and the U-phase parallel connection busbar 41O1 constitute a laminated U-phase laminated busbar 41PNO having a laminated structure in which they are laminated in order from the bottom via the insulating layers 41I1 and 41I2. Therefore, the current density of the U-phase parallel connection busbar 41O1 becomes substantially equal to that of the U-phase positive-side DC busbar 41P and the U-phase negative-side DC busbar 41N.

[0235] As shown in FIGS. 11 and 12, the U-phase parallel connection busbar 41O1 is provided with substantially rectangular and relatively large through-holes at positions corresponding to the six switch modules 410 in a top view. Thereby, the positive-side terminal 410P (i.e., the through-hole for fastening the U-phase positive-side DC busbar 41P), the negative-side terminal 410N (i.e., the through-hole for fastening the U-phase negative-side DC busbar 41N), and the AC output terminal 410O of the switch module 410 can be exposed in a top view. Therefore, an operator can access the positive-side terminal 410P, the negative-side terminal 410N, and the AC output terminal 410O of the switch module 410 from above the U-phase parallel connection busbar 41O1.

[0236] As shown in FIGS. 11 and 12, the U-phase output bus bar 41O2 connects between the U-phase parallel connection bus bar 41O1 and the U-phase output terminal 41T. The U-phase output bus bar 41O2 is connected to a position farther in the positive X-axis direction than the AC output terminal 410O of the switch module 410 at the end of the U-phase parallel connection bus bar 41O1 in the positive X-axis direction, that is, at the end of the three switch modules 410 arranged in the X-axis direction in two rows in the positive X-axis direction. Also, the U-phase output bus bar 41O2 is connected at the end of the U-phase parallel connection bus bar 41O1 in the positive X-axis direction and at a substantially central position in the Y-axis direction between the AC output terminals 410O of the group of three switch modules 410 arranged in two rows in the X-axis direction. Thereby, the lengths of the power paths between the DC input ends of the U-phase circuit 41 passing through each of the six switch modules 410 and the connection part of the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2 are all substantially equal. Therefore, the lengths and current densities of the one-round power paths between the smoothing circuit 20 and the U-phase output terminal 41T passing through each of the six switch modules 410 are all substantially equal. Thus, the inductances of the one-round power paths between the smoothing circuit 20 and the U-phase output terminal 41T passing through the six switch modules 410 can be made substantially equal and uniformized.

[0237] The V-phase circuit 42 includes six switch modules 420 (corresponding to the above-mentioned switch modules 421 to 426), similar to the U-phase circuit 41.

[0238] Since the arrangement structure of the six switch modules 420 is the same as that of the six switch modules 410 of the U-phase circuit 41, the description thereof is omitted.

[0239] The switch module 420 is arranged such that the longitudinal direction in the top view is substantially along the X-axis direction, similar to the switch module 410. In the switch module 420, along its longitudinal direction (i.e., the X-axis direction), the AC output terminal 420O, the negative electrode side terminal 420N, and the positive electrode side terminal 420P are arranged in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21).

[0240] As shown in FIG. 12, on the upper end of the switch module 420, the V-phase laminated bus bar 42PN is arranged substantially parallel to the X-axis direction and the Y-axis direction.

[0241] The V-phase laminated bus bar 42PN is arranged over a range covering six switch modules 420 in the X-axis direction and the Y-axis direction.

[0242] As shown in FIG. 12, the V-phase AC bus bar 42O connects between the AC output terminal 420O of the switch module 420 and the V-phase output terminal 42T. The V-phase AC bus bar 42O includes a V-phase parallel connection bus bar 42O1 and a V-phase output bus bar 42O2.

[0243] The V-phase parallel connection bus bar 42O1 has a substantially flat plate shape parallel to the X-axis direction and the Y-axis direction, and has a substantially rectangular shape covering a range of six switch modules 420 in top view. The V-phase parallel connection bus bar 42O1 is further laminated on the uppermost insulating layer 42I2 (see FIG. 4) of the V-phase laminated bus bar 42PN. Thereby, the V-phase negative-side DC bus bar 42N, the V-phase positive-side DC bus bar 42P, and the V-phase parallel connection bus bar 42O1 constitute a V-phase laminated bus bar 42PNO having a laminated structure laminated in order from the bottom via the insulating layers 42I1 and 42I2. Therefore, the current density of the V-phase parallel connection bus bar 42O1 is substantially equal to that of the V-phase positive-side DC bus bar 42P and the V-phase negative-side DC bus bar 42N.

[0244] Since the arrangement and structure of the V-phase AC bus bar 42O (the V-phase parallel connection bus bar 42O1 and the V-phase output bus bar 42O2) are the same as those of the U-phase AC bus bar 41O, the description thereof is omitted.

[0245] The W-phase circuit 43 includes six switch modules 430 (corresponding to the above-described switch modules 431 to 436), similar to the U-phase circuit 41.

[0246] Since the arrangement structure of the six switch modules 430 is the same as that of the six switch modules 410 of the U-phase circuit 41, the description thereof is omitted.

[0247] Similar to the switch module 410, the switch module 430 is arranged such that the longitudinal direction in the top view is substantially along the X-axis direction. On the switch module 430, along its longitudinal direction (i.e., the X-axis direction), in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21), an AC output terminal 430O, a negative-side terminal 430N, and a positive-side terminal 430P are arranged side by side.

[0248] As shown in FIG. 12, at the upper end of the switch module 430, a W-phase laminated bus bar 43PN is arranged substantially parallel to the X-axis direction and the Y-axis direction.

[0249] The W-phase laminated bus bar 43PN is arranged over a range covering six switch modules 430 in the X-axis direction and the Y-axis direction.

[0250] As shown in FIG. 12, the W-phase AC bus bar 43O connects between the AC output terminal 430O of the switch module 430 and the W-phase output terminal 43T. The W-phase AC bus bar 43O includes a W-phase parallel connection bus bar 43O1 and a W-phase output bus bar 43O2.

[0251] The W-phase parallel connection bus bar 43O1 has a flat plate shape substantially parallel to the X-axis direction and the Y-axis direction, and has a substantially rectangular shape covering a range of six switch modules 430 in the top view. The W-phase parallel connection bus bar 43O1 is further laminated on the uppermost insulating layer 43I2 (see FIG. 4) of the W-phase laminated bus bar 43PN. Thereby, the W-phase negative-side DC bus bar 43N, the W-phase positive-side DC bus bar 43P, and the W-phase parallel connection bus bar 43O1 constitute a laminated W-phase laminated bus bar 43PNO laminated in order from the bottom via the insulating layers 43I1 and 43I2. Therefore, the current density of the W-phase parallel connection bus bar 43O1 becomes substantially equal to that of the W-phase positive-side DC bus bar 43P and the W-phase negative-side DC bus bar 43N.

[0252] The arrangement and structure of the W-phase AC busbar 43O (the W-phase parallel connection busbar 43O1 and the W-phase output busbar 43O2) are the same as those of the U-phase AC busbar 41O, so the description is omitted.

[0253] Thus, in the third embodiment, the U-phase parallel connection bus bar 41O1 has a laminated structure laminated together with the U-phase positive electrode side DC bus bar 41P and the U-phase negative electrode side DC bus bar 41N via insulation layers 41I1 and 41I2. Also, the U-phase parallel connection bus bar 41O1 is connected to the U-phase output bus bar 41O2 at a position farther in the positive X-axis direction than the AC output terminal 410O of the switch module 410 at the end in the positive X-axis direction among the six switch modules 410. Thereby, the lengths and current densities of the one-round power paths between the smoothing circuit 20 passing through each of the six switch modules 410 and the U-phase output terminal 41T all become substantially equal. Therefore, the inductances of the one-round power paths between the smoothing circuit 20 passing through each of the six switch modules 410 and the U-phase output terminal 41T can be made substantially equal and uniformized. Similarly, the V-phase parallel connection bus bar 42O1 has a laminated structure laminated together with the V-phase positive electrode side DC bus bar 42P and the V-phase negative electrode side DC bus bar 42N via insulation layers 42I1 and 42I2. Also, the V-phase parallel connection bus bar 42O1 is connected to the V-phase output bus bar 42O2 at a position farther in the positive X-axis direction than the AC output terminal 420O of the switch module 420 at the end in the positive X-axis direction among the six switch modules 420. Thereby, the lengths and current densities of the one-round power paths between the smoothing circuit 20 passing through each of the six switch modules 420 and the V-phase output terminal 42T all become substantially equal. Therefore, the inductances of the one-round power paths between the smoothing circuit 20 passing through each of the six switch modules 420 and the V-phase output terminal 42T can be made substantially equal and uniformized. Similarly, the W-phase parallel connection bus bar 43O1 has a laminated structure laminated together with the W-phase positive electrode side DC bus bar 43P and the W-phase negative electrode side DC bus bar 43N via insulation layers 43I1 and 43I2. Also, the W-phase parallel connection bus bar 43O1 is connected to the W-phase output bus bar 43O2 at a position farther in the positive X-axis direction than the AC output terminal 430O of the switch module 430 at the end in the positive X-axis direction among the six switch modules 430.As a result, the lengths and current densities of the one-round power paths between the smoothing circuit 20 and the W-phase output terminal 43T passing through each of the six switch modules 430 all become substantially equal. Therefore, the inductances of the one-round power paths between the smoothing circuit 20 and the W-phase output terminal 43T passing through each of the six switch modules 430 can be made substantially equal and uniformized. Thus, the current imbalance among each of the six switch modules 410, the six switch modules 420, and the six switch modules 430 can be suppressed, and current uniformity can be achieved.

[0254] In addition, in the third embodiment, the number of switch modules 410 connected in parallel may be arbitrary, and may be two or more and five or less, or may be seven or more. The same may apply to the number of switch modules 420 and switch modules 430. Also, in the third embodiment, the arrangement of the plurality of switch modules 410 may be arbitrary. For example, the plurality of switch modules 410 may be arranged in a row in the X-axis direction, or a group of one row arranged in the X-axis direction may be arranged in three or more rows in the Y-axis direction.

[0255] [Fourth Embodiment] Next, with reference to FIGS. 13 and 14, the fourth embodiment will be described. Since the circuit configuration of the power conversion device 1 according to the fourth embodiment is the same as that of the above-described second embodiment (FIG. 7), the description thereof will be omitted. Hereinafter, the description will focus on the parts different from the power conversion device 1 according to the first to third embodiments, and the description of the same or corresponding contents as the first to third embodiments may be simplified or omitted.

[0256] <Structure of Power Conversion Device> FIGS. 13 and 14 are structural diagrams showing an example of the power conversion device 1 according to the fourth embodiment. Specifically, FIG. 13 is a perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed. FIG. 14 is an exploded perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed and the output terminal 40T is removed and moved upward.

[0257] As shown in FIGS. 13 and 14, the smoothing circuit 20, the fuse 30, and the inverter circuit 40 are arranged in order from one end to the other end in the longitudinal direction (i.e., in the positive X-axis direction) inside the housing 1H, as in the case of the first embodiment and the like.

[0258] Also, the output terminal 40T is arranged at the central part in the longitudinal direction (X-axis direction) inside the housing 1H and at the upper part inside the housing 1H, as in the case of the first embodiment and the like. Specifically, the output terminal 40T is arranged above the smoothing circuit 20 and the fuse 30 inside the housing 1H.

[0259] The output terminal 40T includes, as described above, a U-phase output terminal 41T, a V-phase output terminal 42T, and a W-phase output terminal 43T. The U-phase output terminal 41T, the V-phase output terminal 42T, and the W-phase output terminal 43T are arranged in order from one end to the central part in the short-side direction (i.e., in the positive Y-axis direction) inside the housing 1H, as in the case of the first embodiment and the like.

[0260] The inverter circuit 40 includes, as described above, a bridge circuit composed of a U-phase circuit 41, a V-phase circuit 42, and a W-phase circuit 43.

[0261] As shown in FIGS. 13 and 14, the U-phase circuit 41, the V-phase circuit 42, and the W-phase circuit 43 are arranged in order in the Y-axis direction from the end in the negative Y-axis direction to the end in the positive Y-axis direction, as in the case of the first embodiment and the like.

[0262] The U-phase circuit 41 includes, as in the case of the second embodiment and the like, six switch modules 410 (i.e., corresponding to the above-described switch modules 411 to 416).

[0263] The six switch modules 410 are arranged in two groups of three arranged at equal intervals in the X-axis direction, arranged in two rows in the Y-axis direction, as in the case of the second embodiment and the like. Also, the six switch modules 410 are arranged on another component placed on the bottom surface of the housing 1H, as in the case of the first embodiment and the like.

[0264] The switch module 410 is arranged such that the longitudinal direction in the top view is along the substantially X-axis direction, similar to the case of the first embodiment and the like. On the switch module 410, along its longitudinal direction (i.e., the X-axis direction), in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21), an AC output terminal 410O, a negative-side terminal 410N, and a positive-side terminal 410P are arranged side by side.

[0265] As shown in FIGS. 13 and 14, on the upper end portion of the switch module 410, similar to the case of the first embodiment and the like, a U-phase laminated bus bar 41PN is arranged substantially parallel to the X-axis direction and the Y-axis direction.

[0266] The U-phase laminated bus bar 41PN is arranged over a range covering six switch modules 410 in the X-axis direction and the Y-axis direction.

[0267] As shown in FIGS. 13 and 14, the U-phase AC bus bar 41O connects between the AC output terminal 410O of the switch module 410 and the U-phase output terminal 41T. The U-phase AC bus bar 41O includes a U-phase parallel connection bus bar 41O1 and a U-phase output bus bar 41O2, similar to the case of the first embodiment and the like.

[0268] The U-phase parallel connection bus bar 41O1 has a substantially flat plate shape substantially parallel to the X-axis direction and the Y-axis direction, and has a substantially rectangular shape covering a range of six switch modules 410 in the top view, similar to the third embodiment. The U-phase parallel connection bus bar 41O1 is further laminated on the uppermost insulating layer 41I2 (see FIG. 4) of the U-phase laminated bus bar 41PN. Thereby, the U-phase negative-side DC bus bar 41N, the U-phase positive-side DC bus bar 41P, and the U-phase parallel connection bus bar 41O1 constitute a laminated U-phase laminated bus bar 41PNO laminated in order from the bottom via the insulating layers 41I1 and 41I2. Therefore, the current density of the U-phase parallel connection bus bar 41O1 becomes substantially equal to that of the U-phase positive-side DC bus bar 41P and the U-phase negative-side DC bus bar 41N.

[0269] As shown in FIGS. 13 and 14, the U-phase output busbar 41O2 connects between the U-phase parallel connection busbar 41O1 and the U-phase output terminal 41T. The U-phase output busbar 41O2 is connected to the end of the U-phase parallel connection busbar 41O1 in the negative X-axis direction, that is, at a position further in the negative X-axis direction than the AC output terminal 410O of the switch module 410 at the end of the three switch modules 410 arranged in two rows in the X-axis direction. Also, the U-phase output busbar 41O2 is connected at the end of the U-phase parallel connection busbar 41O1 in the negative X-axis direction and at a substantially central position in the Y-axis direction between the AC output terminals 410O of the group of three switch modules 410 arranged in two rows in the X-axis direction. Thereby, the direction of the current flowing through the U-phase positive-side DC busbar 41P toward each of the six switch modules 410 is in the positive X-axis direction. On the other hand, the direction of the current flowing from each of the six switch modules 410 through the U-phase parallel connection busbar 41O1 toward the U-phase output terminal 41T is in the opposite negative X-axis direction. Therefore, by flowing currents of the same current density in opposite directions, the magnetic fields generated by the respective currents of the U-phase positive-side DC busbar 41P and the U-phase parallel connection busbar 41O1 are canceled out, and their inductance can be greatly reduced. Similarly, the direction of the current flowing from the U-phase output terminal 41T through the U-phase parallel connection busbar 41O1 toward each of the six switch modules 410 is in the positive X-axis direction. On the other hand, the direction of the current flowing from each of the six switch modules 410 through the U-phase negative-side DC busbar 41N toward the smoothing circuit 20 is in the negative X-axis direction. Therefore, by flowing currents of the same magnitude in opposite directions, the magnetic fields generated by the respective currents of the U-phase negative-side DC busbar 41N and the U-phase parallel connection busbar 41O1 are canceled out, and their inductance can be greatly reduced. Thus, since the inductance of each one-way power path between the smoothing circuit 20 passing through the six switch modules 410 and the U-phase output terminal 41T becomes very small, the difference in inductance between the power paths can be suppressed, and the inductance can be made uniform.

[0270] The V-phase circuit 42 includes six switch modules 420 (corresponding to the above-mentioned switch modules 421 to 426), similar to the U-phase circuit 41.

[0271] Since the arrangement structure of the six switch modules 420 is the same as that of the six switch modules 410 of the U-phase circuit 41, the description is omitted.

[0272] The switch module 420 is arranged such that the longitudinal direction in the top view is substantially along the X-axis direction, similar to the switch module 410. Along the longitudinal direction (i.e., the X-axis direction) of the switch module 420, an AC output terminal 420O, a negative electrode side terminal 420N, and a positive electrode side terminal 420P are arranged in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21).

[0273] As shown in FIGS. 13 and 14, a V-phase laminated bus bar 42PN is arranged substantially parallel to the X-axis direction and the Y-axis direction at the upper end of the switch module 420.

[0274] The V-phase laminated bus bar 42PN is arranged over a range covering the six switch modules 420 in the X-axis direction and the Y-axis direction.

[0275] As shown in FIGS. 13 and 14, the V-phase AC bus bar 42O connects between the AC output terminal 420O of the switch module 420 and the V-phase output terminal 42T. The V-phase AC bus bar 42O includes a V-phase parallel connection bus bar 42O1 and a V-phase output bus bar 42O2.

[0276] The bus bar 42O1 for V-phase parallel connection has a flat plate shape that is substantially parallel to the X-axis direction and the Y-axis direction, and has a substantially rectangular shape covering six switch modules 420 in a top view, similar to the case of the third embodiment. The bus bar 42O1 for V-phase parallel connection is further laminated on the uppermost insulating layer 42I2 (see FIG. 4) of the V-phase laminated bus bar 42PN. As a result, the V-phase negative-side DC bus bar 42N, the V-phase positive-side DC bus bar 42P, and the bus bar 42O1 for V-phase parallel connection constitute a V-phase laminated bus bar 42PNO having a laminated structure that is laminated in order from the bottom via the insulating layers 42I1 and 42I2. Therefore, the current density of the bus bar 42O1 for V-phase parallel connection becomes substantially equal to that of the V-phase positive-side DC bus bar 42P and the V-phase negative-side DC bus bar 42N.

[0277] Since the arrangement and structure of the V-phase AC bus bar 42O (the bus bar 42O1 for V-phase parallel connection and the bus bar 42O2 for V-phase output) are the same as those of the U-phase AC bus bar 41O, the description thereof is omitted.

[0278] The W-phase circuit 43 includes six switch modules 430 (corresponding to the above-described switch modules 431 to 436), similar to the U-phase circuit 41.

[0279] Since the arrangement structure of the six switch modules 430 is the same as that of the six switch modules 410 of the U-phase circuit 41, the description thereof is omitted.

[0280] The switch module 430 is arranged such that the longitudinal direction in a top view is substantially along the X-axis direction, similar to the switch module 410. On the switch module 430, an AC output terminal 430O, a negative-side terminal 430N, and a positive-side terminal 430P are arranged in order from the side closer to the smoothing circuit 20 (smoothing capacitor 21) along the longitudinal direction thereof (i.e., the X-axis direction).

[0281] As shown in FIGS. 13 and 14, a W-phase laminated bus bar 43PN is arranged substantially parallel to the X-axis direction and the Y-axis direction at the upper end portion of the switch module 430.

[0282] The W-phase laminated busbar 43PN is arranged over a range covering six switch modules 430 in the X-axis direction and the Y-axis direction.

[0283] As shown in FIGS. 13 and 14, the W-phase AC busbar 43O connects between the AC output terminal 430O of the switch module 430 and the W-phase output terminal 43T. The W-phase AC busbar 43O includes a W-phase parallel connection busbar 43O1 and a W-phase output busbar 43O2.

[0284] Similar to the case of the third embodiment, the W-phase parallel connection busbar 43O1 has a flat plate shape substantially parallel to the X-axis direction and the Y-axis direction, and has a substantially rectangular shape covering a range of six switch modules 430 in top view. The W-phase parallel connection busbar 43O1 is further laminated on the uppermost insulating layer 43I2 (see FIG. 4) of the W-phase laminated busbar 43PN. Thereby, the W-phase negative side DC busbar 43N, the W-phase positive side DC busbar 43P, and the W-phase parallel connection busbar 43O1 constitute a W-phase laminated busbar 43PNO having a laminated structure laminated in order from bottom via the insulating layers 43I1 and 43I2. Therefore, the current density of the W-phase parallel connection busbar 43O1 becomes substantially equal to that of the W-phase positive side DC busbar 43P and the W-phase negative side DC busbar 43N.

[0285] Since the arrangement and structure of the W-phase AC busbar 43O (the W-phase parallel connection busbar 43O1 and the W-phase output busbar 43O2) are the same as those of the U-phase AC busbar 41O, the description is omitted.

[0286] Thus, in the fourth embodiment, the U-phase parallel connection bus bar 41O1 has a laminated structure laminated together with the U-phase positive electrode side DC bus bar 41P and the U-phase negative electrode side DC bus bar 41N via insulation layers 41I1 and 41I2. Also, the U-phase parallel connection bus bar 41O1 is connected to the U-phase output bus bar 41O2 at a position farther in the negative X-axis direction than the AC output terminal 410O of the switch module 410 at the end in the negative X-axis direction among the six switch modules 410. Thereby, the currents of the U-phase positive electrode side DC bus bar 41P and the U-phase parallel connection bus bar 41O1 before and after passing through each of the six switch modules 410, and the currents of the U-phase parallel connection bus bar 41O1 and the U-phase negative electrode side DC bus bar 41N have the same current density and are opposite in direction in space. Therefore, the magnetic fields generated by the currents of the U-phase positive electrode side DC bus bar 41P and the U-phase parallel connection bus bar 41O1, and the currents of the U-phase parallel connection bus bar 41O1 and the U-phase negative electrode side DC bus bar 41N are canceled out, and the inductance of these power paths can be made very small. As a result, the difference in inductance between the paths of the one-round power path between the smoothing circuit 20 and the U-phase output terminal 41T passing through each of the six switch modules 410 can be suppressed, and the inductance can be made uniform. Similarly, the V-phase parallel connection bus bar 42O1 has a laminated structure laminated together with the V-phase positive electrode side DC bus bar 42P and the V-phase negative electrode side DC bus bar 42N via insulation layers 42I1 and 42I2. Also, the V-phase parallel connection bus bar 42O1 is connected to the V-phase output bus bar 42O2 at a position farther in the negative X-axis direction than the AC output terminal 420O of the switch module 420 at the end in the negative X-axis direction among the six switch modules 420. Thereby, the currents of the V-phase positive electrode side DC bus bar 42P and the V-phase parallel connection bus bar 42O1 before and after passing through each of the six switch modules 420, and the currents of the V-phase parallel connection bus bar 42O1 and the V-phase negative electrode side DC bus bar 42N have the same current density and are opposite in direction in space. Therefore, the magnetic fields generated by the currents of the V-phase positive electrode side DC bus bar 42P and the V-phase parallel connection bus bar 42O1, and the currents of the V-phase parallel connection bus bar 42O1 and the V-phase negative electrode side DC bus bar 42N are canceled out, and the inductance of these power paths can be made very small.As a result, it is possible to suppress the difference in inductance between paths of the power path for one round between the smoothing circuit 20 and the V-phase output terminal 42T passing through each of the six switch modules 420, and to achieve inductance uniformity. Similarly, the W-phase parallel connection bus bar 43O1 has a laminated structure laminated via insulating layers 43I1 and 43I2 together with the W-phase positive-side DC bus bar 43P and the W-phase negative-side DC bus bar 43N. Further, the W-phase parallel connection bus bar 43O1 is connected to the W-phase output bus bar 43O2 at a position farther in the negative X-axis direction than the AC output terminal 430O of the switch module 430 at the end in the negative X-axis direction among the six switch modules 430. Thereby, the currents of the W-phase positive-side DC bus bar 43P and the W-phase parallel connection bus bar 43O1 before and after passing through each of the six switch modules 430, and the currents of the W-phase parallel connection bus bar 43O1 and the W-phase negative-side DC bus bar 43N have the same current density and are opposite in direction in space. Therefore, the magnetic fields generated by the currents of the W-phase positive-side DC bus bar 43P and the W-phase parallel connection bus bar 43O1, and the currents of the W-phase parallel connection bus bar 43O1 and the W-phase negative-side DC bus bar 43N are canceled out, and the inductance of these power paths can be made very small. As a result, it is possible to suppress the difference in inductance between paths of the power path for one round between the smoothing circuit 20 and the W-phase output terminal 43T passing through each of the six switch modules 430, and to achieve inductance uniformity. Thus, it is possible to suppress the imbalance of the currents of each of the six switch modules 410, the six switch modules 420, and the six switch modules 430, and to achieve current uniformity.

[0287] Furthermore, in the fourth embodiment, the number of switch modules 410 connected in parallel may be arbitrary, and may be two or more and five or less, or may be seven or more. The same applies to the number of switch modules 420 and switch modules 430. Also, in the fourth embodiment, the arrangement of the plurality of switch modules 410 may be arbitrary. For example, the plurality of switch modules 410 may be arranged in a row in the X-axis direction, or a group of one row arranged in the X-axis direction may be arranged in three or more rows in the Y-axis direction.

[0288] [Operation] Next, the operation of the power conversion device 1 according to this embodiment will be described.

[0289] In this embodiment (the first embodiment), the power conversion device 1 includes a smoothing circuit 20, an inverter circuit 40, and an output terminal 40T. Specifically, the inverter circuit 40 includes a switch module 410 in which upper and lower arms each including a plurality of semiconductor switches 410s are connected in series, and a plurality of the switch modules 410 are connected in parallel. The connection points (AC output terminals 410O) of the upper and lower arms of each of the plurality of switch modules 410 are connected to each other, thereby forming a U-phase circuit 41. Similarly, the inverter circuit 40 includes a switch module 420 in which upper and lower arms each including a plurality of semiconductor switches 420s are connected in series, and a plurality of the switch modules 420 are connected in parallel. The connection points (AC output terminals 420O) of the upper and lower arms of each of the plurality of switch modules 420 are connected to each other, thereby forming a V-phase circuit 42. Similarly, the inverter circuit 40 includes a switch module 430 in which upper and lower arms each including a plurality of semiconductor switches 430s are connected in series, and a plurality of the switch modules 430 are connected in parallel. The connection points (AC output terminals 430O) of the upper and lower arms of each of the plurality of switch modules 430 are connected to each other, thereby forming a W-phase circuit 43. That is, the inverter circuit 40 includes a bridge circuit formed by connecting a plurality of output circuits (U-phase circuit 41, V-phase circuit 42, and W-phase circuit 43) in parallel for a plurality of phases. Then, the inverter circuit 40 outputs predetermined AC power based on the DC power input from the smoothing circuit 20. Further, the output terminal 40T outputs the predetermined AC power from the inverter circuit 40 to the outside. Also, the inverter circuit 40 includes a positive-side DC bus bar 40P that connects the positive-side terminals 410P, 420P, and 430P of the plurality of switch modules 410, 420, and 430 to each other, and a negative-side DC bus bar 40N that connects the negative-side terminals 410N, 420N, and 430N of the plurality of switch modules 410, 420, and 430 to each other. Further, the inverter circuit 40 includes a U-phase parallel connection bus bar 41O1 that connects the AC output terminals 410O of the plurality of switch modules 410 to each other. Similarly, the inverter circuit 40 includes a V-phase parallel connection bus bar 42O1 that connects the AC output terminals 420O of the plurality of switch modules 420 to each other. Similarly, the inverter circuit 40 includes a W-phase parallel connection bus bar 43O1 that connects the AC output terminals 430O of the plurality of switch modules 430 to each other.Further, the positive electrode side DC bus bar 40P and the negative electrode side DC bus bar 40N have a laminated structure laminated via insulating layers 41I1, 42I1, 43I1. And the U-phase parallel connection bus bar 41O1 is configured such that the lengths of the respective paths between all the arms (semiconductor switches 410s) included in the plurality of switch modules 410 and the junction where all the paths from each of the plurality of switch modules 410 merge are substantially equal. Similarly, the V-phase parallel connection bus bar 42O1 is configured such that the lengths of the respective paths between all the arms (semiconductor switches 420s) included in the plurality of switch modules 420 and the junction where all the paths from each of the plurality of switch modules 420 merge are substantially equal. Similarly, the W-phase parallel connection bus bar 43O1 is configured such that the lengths of the respective paths between all the arms (semiconductor switches 430s) included in the plurality of switch modules 430 and the junction where all the paths from each of the plurality of switch modules 430 merge are substantially equal.

[0290] For example, in an inverter circuit, by connecting a plurality of switch legs in parallel, the current capacity of the power conversion device can be increased.

[0291] In this case, if the inductance is different for each path passing through the plurality of switch legs, an imbalance occurs in the current passing through the plurality of switch legs, and there is a possibility that the current concentrates on the semiconductor switches included in some of the switch legs. As a result, the elements of the semiconductor switches may be damaged due to temperature rise caused by losses.

[0292] On the other hand, by adjusting to the allowable current of the semiconductor switch where the current most concentrates, it is also possible to determine the current capacity of the power conversion device in consideration of the current imbalance. However, in this case, only a relatively lower current than the allowable current flows through the semiconductor switches other than the semiconductor switch where the current concentrates. As a result, even if the number of switch legs connected in parallel is increased, the allowable current of the entire plurality of switch legs cannot be effectively used, and there is a possibility that the current capacity of the power conversion device cannot be increased very much.

[0293] In contrast, in this embodiment (the first embodiment), with the lamination structuring of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N, the inductance of the DC wiring portions on the positive and negative sides of the inverter circuit 40 can be made extremely small. Therefore, with respect to the inductance of the one-way power path between the smoothing circuit 20 and the output terminal 40T, the inductance of the AC wiring portion becomes dominant. Furthermore, by configuring the respective path lengths from all the arms (semiconductor switches 410s) included in the plurality of switch modules 410 to the confluence portion to be substantially equal, the difference in the inductance of the power paths passing through the respective semiconductor switches 410s in the U-phase parallel connection bus bar 41O1 can be relatively reduced. Therefore, for the power paths passing through the respective ones of the plurality of switch modules 410, the power conversion device 1 can relatively reduce the difference in the inductance of the one-way power path between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T). Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 410s (switch modules 410) and achieve current equalization. The same also applies to the plurality of switch modules 420. Therefore, for the power paths passing through the respective ones of the plurality of switch modules 420, the power conversion device 1 can relatively reduce the difference in the inductance of the one-way power path between the smoothing circuit 20 and the output terminal 40T (V-phase output terminal 42T). Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 420s (switch modules 420) and achieve current equalization. The same also applies to the plurality of switch modules 430. Therefore, for the power paths passing through the respective ones of the plurality of switch modules 430, the power conversion device 1 can relatively reduce the difference in the inductance of the one-way power path between the smoothing circuit 20 and the output terminal 40T (W-phase output terminal 43T). Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 430s (switch modules 430) and achieve current equalization.

[0294] Also, in this embodiment (the first embodiment), the U-phase parallel connection busbar 41O1 is configured such that the current density for each path between all the semiconductor switches 410s included in the plurality of switch modules 410 and the confluence portion where all the paths from each of the plurality of switch modules 410 merge is substantially equal. The same may apply to the V-phase parallel connection busbar 42O1 and the W-phase parallel connection busbar 43O1.

[0295] Thereby, the inductances of the power paths passing through the respective semiconductor switches 410s in the U-phase parallel connection busbar 41O1 can be made substantially equal. Therefore, for the power paths passing through each of the plurality of switch modules 410, the power conversion device 1 can make the inductances of the one-round power paths between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T) substantially equal. Thus, the power conversion device 1 can further suppress the current imbalance among the plurality of semiconductor switches 410s (switch modules 410) and further achieve current equalization. The same operations and effects also apply to the V-phase parallel connection busbar 42O1 and the W-phase parallel connection busbar 43O1.

[0296] Also, in this embodiment (the first embodiment), two switch modules 410 included in the plurality of switch modules 410 are arranged side by side in one axial direction (the X-axis direction). The same may apply to the plurality of switch modules 420 and the plurality of switch modules 430. And the U-phase parallel connection busbar 41O1 may merge the paths from the two switch modules 410 toward the U-phase output terminal 41T at a substantially central position (midpoint) between the AC output terminals 410O of the two switch modules 410 in the X-axis direction. The same may apply to the V-phase parallel connection busbar 42O1 and the W-phase parallel connection busbar 43O1.

[0297] As a result, for the bus bar 41O1 for U-phase parallel connection, for each combination of two switch modules 410, the paths from the AC output terminals 410O of the two switch modules 410 can be merged so that their lengths are substantially the same. The same operation and effect also apply to the bus bar 42O1 for V-phase parallel connection and the bus bar 43O1 for W-phase parallel connection.

[0298] Also, in this embodiment (the first embodiment), the plurality of switch modules 410 connected in parallel may include a plurality of combinations of two switch modules 410. The same may also apply to the plurality of switch modules 420 connected in parallel and the plurality of switch modules 430 connected in parallel. And the bus bar 41O1 for U-phase parallel connection may be configured such that the lengths of the respective power paths between the intermediate merging portion where the paths from the respective two switch modules 410 for each of the plurality of combinations merge and the merging portion where the paths from all the switch modules 410 merge are substantially equal. The same may also apply to the bus bar 42O1 for V-phase parallel connection and the bus bar 43O1 for W-phase parallel connection.

[0299] As a result, in the bus bar 41O1 for U-phase parallel connection, the lengths of the paths until all the paths from the respective plurality of switch modules 410 connected in parallel merge can be made substantially equal. The same operation and effect also apply to the bus bar 42O1 for V-phase parallel connection and the bus bar 43O1 for W-phase parallel connection.

[0300] In addition, in this embodiment (the first embodiment), the plurality (four) of switch modules 410 connected in parallel may be arranged in two columns in another axial direction (Y-axis direction) perpendicular to the X-axis direction with two of the two sets of switch modules 410 aligned in the X-axis direction. The same may apply to the plurality (four) of switch modules 420 and the plurality (four) of switch modules 430. Further, the U-phase parallel connection busbar 41O1 is configured to be substantially plane-symmetric with respect to the vertical plane at the central position between the two switch modules 410 in the X-axis direction. Further, the U-phase parallel connection busbar 41O1 may be configured to be substantially plane-symmetric with respect to the vertical planes at the central positions of the two sets in the Y-axis direction. And the connection portion of the U-phase parallel connection busbar 41O1 with the wiring (U-phase output busbar 41O2) to the U-phase output terminal 41T may be configured to be at the central position between the four switch modules 410 included in the two sets in the X-axis direction and the Y-axis direction. The same may apply to the V-phase parallel connection busbar 42O1 and the W-phase parallel connection busbar 43O1.

[0301] As a result, in the U-phase parallel connection busbar 41O1, specifically, the lengths of the respective paths until the respective paths of the plurality (four) of switch modules 410 connected in parallel merge can be made substantially equal. Therefore, the power conversion device 1 can specifically make the inductances of the paths passing through the respective semiconductor switches 410s substantially equal. The same operations and effects also apply to the V-phase parallel connection busbar 42O1 and the W-phase parallel connection busbar 43O1.

[0302] Also, in this embodiment (the second embodiment), the power conversion device 1 includes a smoothing circuit 20, an inverter circuit 40, and an output terminal 40T. Specifically, the inverter circuit 40 includes a switch module 410 in which upper and lower arms each including a plurality of semiconductor switches 410s are connected in series, and a plurality of the switch modules 410 are connected in parallel. The connection points (AC output terminals 410O) of the upper and lower arms of each of the plurality of switch modules 410 are connected to each other, thereby forming a U-phase circuit 41. Similarly, the inverter circuit 40 includes a switch module 420 in which upper and lower arms each including a plurality of semiconductor switches 420s are connected in series, and a plurality of the switch modules 420 are connected in parallel. The connection points (AC output terminals 420O) of the upper and lower arms of each of the plurality of switch modules 420 are connected to each other, thereby forming a V-phase circuit 42. Similarly, the inverter circuit 40 includes a switch module 430 in which upper and lower arms each including a plurality of semiconductor switches 430s are connected in series, and a plurality of the switch modules 430 are connected in parallel. The connection points (AC output terminals 430O) of the upper and lower arms of each of the plurality of switch modules 430 are connected to each other, thereby forming a W-phase circuit 43. That is, the inverter circuit 40 includes a bridge circuit formed by connecting a plurality of output circuits (U-phase circuit 41, V-phase circuit 42, and W-phase circuit 43) in parallel for a plurality of phases. The inverter circuit 40 outputs predetermined AC power based on the DC power input from the smoothing circuit 20. The output terminal 40T outputs the predetermined AC power from the inverter circuit 40 to the outside. The inverter circuit 40 also includes a positive-side DC bus bar 40P that connects the positive-side terminals 410P, 420P, 430P of the plurality of switch modules 410, 420, 430 to each other, and a negative-side DC bus bar 40N that connects the negative-side terminals 410N, 420N, 430N of the plurality of switch modules 410, 420, 430 to each other. The inverter circuit 40 also includes a U-phase parallel connection bus bar 41O1 that connects the AC output terminals 410O of the plurality of switch modules 410 to each other. Similarly, the inverter circuit 40 includes a V-phase parallel connection bus bar 42O1 that connects the AC output terminals 420O of the plurality of switch modules 420 to each other.Similarly, the inverter circuit 40 includes a W-phase parallel connection bus bar 43O1 that connects the AC output terminals 430O of a plurality of switch modules 430. Also, the positive-side DC bus bar 40P and the negative-side DC bus bar 40N have a laminated structure laminated via insulating layers 41I1, 42I1, 43I1. Further, the U-phase parallel connection bus bar 41O1 is configured such that the lengths of the power paths between the smoothing circuit 20 and the junction where the paths from each of the plurality of switch modules 410 merge, passing through each of all the arms (semiconductor switches 410s) included in the plurality of switch modules 410, are substantially equal. And the U-phase parallel connection bus bar 41O1 is configured such that the current density across the entire path of each power path between the smoothing circuit 20 and the above-mentioned junction, passing through each of all the arms included in the plurality of switch modules 410, is substantially equal. Similarly, the V-phase parallel connection bus bar 42O1 is configured such that the lengths of the power paths between the smoothing circuit 20 and the junction where the paths from each of the plurality of switch modules 420 merge, passing through each of all the arms (semiconductor switches 420s) included in the plurality of switch modules 420, are substantially equal. And the V-phase parallel connection bus bar 42O1 is configured such that the current density across the entire path of each power path between the smoothing circuit 20 and the above-mentioned junction, passing through each of all the arms included in the plurality of switch modules 420, is substantially equal. Similarly, the W-phase parallel connection bus bar 43O1 is configured such that the lengths of the power paths between the smoothing circuit 20 and the junction where the paths from each of the plurality of switch modules 430 merge, passing through each of all the arms (semiconductor switches 430s) included in the plurality of switch modules 430, are substantially equal. And the W-phase parallel connection bus bar 43O1 is configured such that the current density across the entire path of each power path between the smoothing circuit 20 and the above-mentioned junction, passing through each of all the arms included in the plurality of switch modules 430, is substantially equal.

[0303] As a result, in the inverter circuit 40, it is possible to equalize the lengths of all paths between the DC input and the junction of the AC outputs and the current density across the entire path for each path. Therefore, for the power path passing through each of the plurality of switch modules 410 in the power conversion device 1, it is possible to make the inductance of the one-round power path between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T) substantially equal. Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 410s (switch modules 410) and achieve current equalization. The same applies to the plurality of switch modules 420. Therefore, for the power path passing through each of the plurality of switch modules 420 in the power conversion device 1, it is possible to make the inductance of the one-round power path between the smoothing circuit 20 and the output terminal 40T (V-phase output terminal 42T) substantially equal. Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 420s (switch modules 420) and achieve current equalization. The same applies to the plurality of switch modules 430. Therefore, for the power path passing through each of the plurality of switch modules 430 in the power conversion device 1, it is possible to make the inductance of the one-round power path between the smoothing circuit 20 and the output terminal 40T (W-phase output terminal 43T) substantially equal. Thus, the power conversion device 1 can suppress the current imbalance of each of the plurality of semiconductor switches 430s (switch modules 430) and achieve current equalization.

[0304] Further, in the present embodiment (second embodiment), the U-phase parallel connection bus bar 41O1 may be configured such that the current density of the common portion of the lengths of the power paths passing through each of the plurality of switch modules 410 is substantially equal. And the U-phase parallel connection bus bar 41O1 may be configured such that the current density of the other portion, that is, the portion corresponding to the difference in the lengths of the respective power paths, is substantially equal to the current density of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N for each power path. The same may apply to the V-phase parallel connection bus bar 42O1 and the W-phase parallel connection bus bar 43O1.

[0305] As a result, in the inverter circuit 40, it is possible to make the current density substantially equal across the entire path for each path between the DC input and the junction of the AC input.

[0306] Further, in the present embodiment (second embodiment), the smoothing circuit 20 and the inverter circuit 40 may be arranged side by side in one axial direction (X-axis direction). Further, the plurality of switch modules 410 may be arranged side by side in the X-axis direction. The same may apply to the plurality of switch modules 420 and the plurality of switch modules 430. Also, the U-phase parallel connection busbar 41O1 may be provided so as to extend in the vertical direction (Z-axis direction) from the connection points (AC output terminals 410O) of the upper and lower arms of each of the plurality of switch modules 410, and may include a plurality of leg portions 41O1a having substantially the same length and substantially the same cross-sectional area. Further, the U-phase parallel connection busbar 41O1 may include a connecting portion 41O1b that connects the plurality of leg portions 41O1a so as to extend in the X-axis direction. Further, the connecting portion 41O1b may be connected to the wiring (U-phase output busbar 41O2) up to the output terminal 40T (U-phase output terminal 41T) at the end away from the smoothing circuit 20 in the X-axis direction. And the connecting portion 41O1b may be configured such that the current density is substantially equal to the current density of the positive-side DC busbar 40P and the negative-side DC busbar 40N for each power path passing through each of the plurality of switch modules 410. The same may apply to the V-phase parallel connection busbar 42O1 and the W-phase parallel connection busbar 43O1.

[0307] As a result, in the inverter circuit 40, specifically, it is possible to make the lengths of all power paths between the DC input and the junction of the AC output and the current density across the entire path for each power path substantially equal.

[0308] Further, in this embodiment (the second embodiment), two groups of a plurality of switch modules 410 arranged in one axial direction (X-axis direction) may be arranged in two rows in another axial direction (Y-axis direction) perpendicular to the X-axis direction. Then, the connecting portion 41O1b of the U-phase parallel connection bus bar 41O1 may connect a plurality of leg portions 41O1a so as to extend in the X-axis direction and the Y-axis direction.

[0309] As a result, in the inverter circuit 40, specifically, the lengths of all power paths between the DC input and the junction of the AC output and the current density over the entire path for each power path can be made substantially equal.

[0310] Also, in this embodiment (the third embodiment), the power conversion device 1 includes a smoothing circuit 20, an inverter circuit 40, and an output terminal 40T. Specifically, the inverter circuit 40 includes a switch module 410 in which upper and lower arms including a plurality of semiconductor switches 410s are connected in series, and a plurality of switch modules 410 are connected in parallel. The connection points (AC output terminals 410O) of the upper and lower arms of each of the plurality of switch modules 410 are connected to each other to form a U-phase circuit 41. Similarly, the inverter circuit 40 includes a switch module 420 in which upper and lower arms including a plurality of semiconductor switches 420s are connected in series, and a plurality of switch modules 420 are connected in parallel. The connection points (AC output terminals 420O) of the upper and lower arms of each of the plurality of switch modules 420 are connected to each other to form a V-phase circuit 42. Similarly, the inverter circuit 40 includes a switch module 430 in which upper and lower arms including a plurality of semiconductor switches 430s are connected in series, and a plurality of switch modules 430 are connected in parallel. The connection points (AC output terminals 430O) of the upper and lower arms of each of the plurality of switch modules 430 are connected to each other to form a W-phase circuit 43. That is, the inverter circuit 40 includes a bridge circuit formed by connecting a plurality of output circuits (U-phase circuit 41, V-phase circuit 42, and W-phase circuit 43) in parallel for a plurality of phases. Then, the inverter circuit 40 outputs a predetermined AC power based on the DC power input from the smoothing circuit 20. The output terminal 40T outputs the predetermined AC power from the inverter circuit 40 to the outside. The inverter circuit 40 also includes a positive-side DC bus bar 40P that connects the positive-side terminals 410P, 420P, 430P of the plurality of switch modules 410, 420, 430 to each other, and a negative-side DC bus bar 40N that connects the negative-side terminals 410N, 420N, 430N of the plurality of switch modules 410, 420, 430 to each other. The inverter circuit 40 also includes a U-phase parallel connection bus bar 41O1 that connects the AC output terminals 410O of the plurality of switch modules 410 to each other. The positive-side DC bus bar 40P, the negative-side DC bus bar 40N, and the U-phase parallel connection bus bar 41O1 have a laminated structure laminated via insulating layers 41I1, 41I2.Similarly, the inverter circuit 40 includes a V-phase parallel connection bus bar 42O1 that connects the AC output terminals 420O of a plurality of switch modules 420. Also, the positive-side DC bus bar 40P, the negative-side DC bus bar 40N, and the V-phase parallel connection bus bar 42O1 have a laminated structure laminated via insulating layers 42I1 and 42I2. Similarly, the inverter circuit 40 includes a W-phase parallel connection bus bar 43O1 that connects the AC output terminals 430O of a plurality of switch modules 430. Also, the positive-side DC bus bar 40P, the negative-side DC bus bar 40N, and the W-phase parallel connection bus bar 43O1 have a laminated structure laminated via insulating layers 43I1 and 43I2. And the connection part between the U-phase parallel connection bus bar 41O1 and the wiring to the output terminal 40T (U-phase output terminal 41T) (U-phase output bus bar 41O2) is provided at a position farther from the smoothing circuit 20 than the semiconductor switch 410s that is farthest from the smoothing circuit 20 among all the arms (semiconductor switches 410s) included in the plurality of switch modules 410. Similarly, the connection part between the V-phase parallel connection bus bar 42O1 and the wiring to the output terminal 40T (V-phase output terminal 42T) is provided at a position farther from the smoothing circuit 20 than the semiconductor switch 420s that is farthest from the smoothing circuit 20 among all the arms (semiconductor switches 420s) included in the plurality of switch modules 420. Similarly, the connection part between the W-phase parallel connection bus bar 43O1 and the wiring to the output terminal 40T (W-phase output terminal 43T) is provided at a position farther from the smoothing circuit 20 than the semiconductor switch 430s that is farthest from the smoothing circuit 20 among all the arms (semiconductor switches 430s) included in the plurality of switch modules 430.

[0311] As a result, with the lamination structuring of the bus bar of the inverter circuit 40, the current density of all power paths between the DC input of the inverter circuit 40 and the confluence part of the AC input can be made substantially uniform. Moreover, with the arrangement of the connection part between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2, a confluence part where paths from each of the plurality of switch modules 410 converge is set near the semiconductor switch 410s that is farthest from the smoothing circuit 20. That is, the lengths of all power paths between the DC input and the confluence part of the AC output in the inverter circuit 40 passing through each of the plurality of switch modules 410 can be made substantially equal. Therefore, the power conversion device 1 can make the inductances of all the round-trip power paths between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T) passing through each of the plurality of switch modules 410 substantially equal. Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 410s (switch modules 410) and achieve current uniformity. The same also applies to the plurality of switch modules 420. Therefore, the power conversion device 1 can make the inductances of all the round-trip power paths between the smoothing circuit 20 and the output terminal 40T (V-phase output terminal 42T) passing through each of the plurality of switch modules 420 substantially equal. Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 420s (switch modules 420) and achieve current uniformity. The same also applies to the plurality of switch modules 430. Therefore, the power conversion device 1 can make the inductances of all the round-trip power paths between the smoothing circuit 20 and the output terminal 40T (W-phase output terminal 43T) passing through each of the plurality of switch modules 430 substantially equal. Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 430s (switch modules 430) and achieve current uniformity.

[0312] Also, in the present embodiment (the third embodiment), the smoothing circuit 20 and the inverter circuit 40 may be arranged side by side in one axial direction (the X-axis direction). And the connection part between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2 may be arranged at a position farther from the smoothing circuit 20 than the switch module 410 farthest from the smoothing circuit 20 among the plurality of switch modules 410 in the X-axis direction. The same may apply to the connection part between the V-phase parallel connection bus bar 42O1 and the V-phase output bus bar 42O2 and the connection part between the W-phase parallel connection bus bar 43O1 and the W-phase output bus bar 43O2.

[0313] For example, the plurality of switch modules 410 may be arranged in two rows in another axial direction (the Y-axis direction) perpendicular to the X-axis direction, with two groups arranged side by side in the X-axis direction. The same may apply to the plurality of switch modules 420 and the plurality of switch modules 430. And the connection part between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2 may be arranged at a position farther from the end part farther from the two groups of smoothing circuits 20 in the X-axis direction and at a substantially central position of the two groups in the Y-axis direction. The same may apply to the connection part between the V-phase parallel connection bus bar 42O1 and the V-phase output bus bar 42O2 and the connection part between the W-phase parallel connection bus bar 43O1 and the W-phase output bus bar 43O2.

[0314] Thereby, in the inverter circuit 40, specifically, the lengths of the power paths between the DC input and the confluence part of the AC output can be made substantially equal.

[0315] Also, in this embodiment (the fourth embodiment), the power conversion device 1 includes a smoothing circuit 20, an inverter circuit 40, and an output terminal 40T. Specifically, the inverter circuit 40 includes a switch module 410 in which upper and lower arms including a plurality of semiconductor switches 410s are connected in series, and a plurality of switch modules 410 are connected in parallel. The connection points (AC output terminals 410O) of the upper and lower arms of each of the plurality of switch modules 410 are connected to each other to form a U-phase circuit 41. Similarly, the inverter circuit 40 includes a switch module 420 in which upper and lower arms including a plurality of semiconductor switches 420s are connected in series, and a plurality of switch modules 420 are connected in parallel. The connection points (AC output terminals 420O) of the upper and lower arms of each of the plurality of switch modules 420 are connected to each other to form a V-phase circuit 42. Similarly, the inverter circuit 40 includes a switch module 430 in which upper and lower arms including a plurality of semiconductor switches 430s are connected in series, and a plurality of switch modules 430 are connected in parallel. The connection points (AC output terminals 430O) of the upper and lower arms of each of the plurality of switch modules 430 are connected to each other to form a W-phase circuit 43. That is, the inverter circuit 40 includes a bridge circuit formed by connecting a plurality of phases of output circuits (U-phase circuit 41, V-phase circuit 42, and W-phase circuit 43) in parallel. The inverter circuit 40 outputs a predetermined AC power based on the DC power input from the smoothing circuit 20. The output terminal 40T outputs the predetermined AC power from the inverter circuit 40 to the outside. The inverter circuit 40 also includes a positive-side DC bus bar 40P that connects the positive-side terminals 410P, 420P, 430P of the plurality of switch modules 410, 420, 430 to each other, and a negative-side DC bus bar 40N that connects the negative-side terminals 410N, 420N, 430N of the plurality of switch modules 410, 420, 430 to each other. The inverter circuit 40 also includes a U-phase parallel connection bus bar 41O1 that connects the AC output terminals 410O of the plurality of switch modules 410 to each other. The positive-side DC bus bar 40P, the negative-side DC bus bar 40N, and the U-phase parallel connection bus bar 41O1 have a laminated structure laminated via insulating layers 41I1, 41I2.Similarly, the inverter circuit 40 includes a V-phase parallel connection bus bar 42O1 that connects the AC output terminals 420O of a plurality of switch modules 420. Also, the positive-side DC bus bar 40P, the negative-side DC bus bar 40N, and the V-phase parallel connection bus bar 42O1 have a laminated structure laminated via insulating layers 42I1 and 42I2. Similarly, the inverter circuit 40 includes a W-phase parallel connection bus bar 43O1 that connects the AC output terminals 430O of a plurality of switch modules 430. Also, the positive-side DC bus bar 40P, the negative-side DC bus bar 40N, and the W-phase parallel connection bus bar 43O1 have a laminated structure laminated via insulating layers 43I1 and 43I2. And the connection portion between the U-phase parallel connection bus bar 41O1 and the wiring (U-phase output bus bar 41O2) to the output terminal 40T (U-phase output terminal 41T) is provided at a position closer to the smoothing circuit 20 than the semiconductor switch 410s closest to the smoothing circuit 20 among all the arms (semiconductor switches 410s) included in the plurality of switch modules 410. Similarly, the connection portion between the V-phase parallel connection bus bar 42O1 and the wiring (V-phase output bus bar 42O2) to the output terminal 40T (V-phase output terminal 42T) is provided at a position closer to the smoothing circuit 20 than the semiconductor switch 420s closest to the smoothing circuit 20 among all the arms (semiconductor switches 420s) included in the plurality of switch modules 420. Similarly, the connection portion between the W-phase parallel connection bus bar 43O1 and the wiring (W-phase output bus bar 43O2) to the output terminal 40T (W-phase output terminal 43T) is provided at a position closer to the smoothing circuit 20 than the semiconductor switch 430s closest to the smoothing circuit 20 among all the arms (semiconductor switches 430s) included in the plurality of switch modules 430.

[0316] As a result, with the lamination structuring of the bus bars of the inverter circuit 40, the current density of all power paths between the DC input of the inverter circuit 40 and the confluence of the AC input can be made substantially uniform. Moreover, with the arrangement of the connection part between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2, in real space, the direction of the current in the U-phase positive-side DC bus bar 41P can be made opposite to the direction of the current in the U-phase parallel connection bus bar 41O1. Similarly, the direction of the current in the U-phase parallel connection bus bar 41O1 can be made opposite to the direction of the current in the U-phase negative-side DC bus bar 41N. Therefore, by having currents of substantially the same current density flow in opposite directions, the generated magnetic fields cancel each other out, reducing the inductance of the U-phase positive-side DC bus bar 41P, the U-phase negative-side DC bus bar 41N, and the U-phase parallel connection bus bar 41O1 to a very small value. As a result, the difference in inductance of all power paths between the DC input and the confluence of the AC input passing through the plurality of switch modules 410 becomes small, enabling the inductance to be made uniform among the power paths. Therefore, the power conversion device 1 can suppress the difference in inductance of the round-trip power path between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T) passing through each of the plurality of switch modules 410 to a very small value. Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 410s (switch modules 410) and achieve current uniformity. The same applies to the plurality of switch modules 420. Therefore, the power conversion device 1 can suppress the difference in inductance of the round-trip power path between the smoothing circuit 20 and the output terminal 40T (V-phase output terminal 42T) passing through each of the plurality of switch modules 420 to a very small value. Thus, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 420s (switch modules 420) and achieve current uniformity. The same applies to the plurality of switch modules 430. Therefore, the power conversion device 1 can suppress the difference in inductance of the round-trip power path between the smoothing circuit 20 and the output terminal 40T (W-phase output terminal 43T) passing through each of the plurality of switch modules 430 to a very small value.Therefore, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 430s (switch module 430) and achieve current equalization.

[0317] Also, in the present embodiment (the fourth embodiment), the smoothing circuit 20 and the inverter circuit 40 may be arranged side by side in one axial direction (X-axis direction). And the connection portion between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2 may be arranged at a position closer to the smoothing circuit 20 than the switch module 410 closest to the smoothing circuit 20 among the plurality of switch modules 410 in the X-axis direction. The same may apply to the connection portion between the V-phase parallel connection bus bar 42O1 and the V-phase output bus bar 42O2 and the connection portion between the W-phase parallel connection bus bar 43O1 and the W-phase output bus bar 43O2.

[0318] For example, in a top view, the plurality of switch modules 410 are arranged in two groups each arranged in the X-axis direction and arranged in two columns in another axial direction (Y-axis direction) perpendicular to the X-axis direction. The same applies to the plurality of switch modules 420 and the plurality of switch modules 430. And the connection portion between the U-phase parallel connection bus bar 41O1 and the wiring to the U-phase output terminal 41T (U-phase output bus bar 41O2) may be arranged at a position closer to the smoothing circuit 20 than the end portions close to the smoothing circuit 20 of the two groups in the X-axis direction. The same applies to the connection portion between the V-phase parallel connection bus bar 42O1 and the wiring to the V-phase output terminal 42T (V-phase output bus bar 42O2) and the connection portion between the W-phase parallel connection bus bar 43O1 and the wiring to the W-phase output terminal 43T (W-phase output bus bar 43O2).

[0319] Specifically, the directions of current in the U-phase positive side DC busbar 41P and the U-phase parallel connection busbar 41O1, and the directions of current in the U-phase parallel connection busbar 41O1 and the U-phase negative side DC busbar 41N in the real space can be reversed. Similarly, the directions of current in the V-phase positive side DC busbar 42P and the V-phase parallel connection busbar 42O1, and the directions of current in the V-phase parallel connection busbar 42O1 and the V-phase negative side DC busbar 42N in the real space can be reversed. Similarly, the directions of current in the W-phase positive side DC busbar 43P and the W-phase parallel connection busbar 43O1, and the directions of current in the W-phase parallel connection busbar 43O1 and the W-phase negative side DC busbar 43N in the real space can be reversed.

[0320] Although the embodiments have been described in detail above, the present disclosure is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist described in the claims. [Explanation of symbols]

[0321] 1 Power conversion device 10 Rectifier circuit 20 Smoothing circuit 20I1, 20I2 Insulation layer 20N Negative busbar 20P positive bus bar 20PN Laminated Busbar 21 Smoothing capacitor 21P Positive terminal 21N Negative terminal 30. Fuse 40 Inverter circuit 40N negative DC busbar 40P positive DC busbar 40PN Laminated Busbar 40T output terminal 41 U phase circuit (output circuit) 41I1, 41I2 Insulating layer 41N U phase negative side DC bus bar 41O U-phase AC busbar 41O1 Busbar for U-phase parallel connection 41O2 Busbar for U-phase output 41P DC busbar for the positive electrode side of the U-phase 41PN, 41PNO U-phase laminated busbar 41T U-phase output terminal 42 V-phase circuit (output circuit) 42I1, 42I2 Insulation layer 42N DC busbar for the negative electrode side of the V-phase 42O AC busbar for the V-phase 42O1 Busbar for V-phase parallel connection 42O2 Busbar for V-phase output 42P DC busbar for the positive electrode side of the V-phase 42PN, 42PNO V-phase laminated busbar 42T V-phase output terminal 43 W-phase circuit (output circuit) 43I1, 43I2 Insulation layer 43N DC busbar for the negative electrode side of the W-phase 43O AC busbar for the W-phase 43O1 Busbar for W-phase parallel connection 43O2 Busbar for W-phase output 43P DC busbar for the positive electrode side of the W-phase 43PN, 43PNO W-phase laminated busbar 43T W-phase output terminal 410~416 Switch module (switch leg) 410N~416N Negative electrode side terminal 410O~416O AC output terminal (connection point) 410P~416P Positive electrode side terminal 410s, 411s1~416s1, 411s2~416s2 Semiconductor switch 411d1~416d1, 411d2~416d2 Circulating diode 420~426 Switch module (switch leg) 420N~426N Negative electrode side terminal 420O~426O AC output terminal (connection point) 420P~426P Positive electrode side terminal 420s, 421s1 to 426s1, 421s2 to 426s2 semiconductor switches 421d1 to 426d1, 421d2 to 426d2 freewheeling diodes 430 to 436 switch modules (switch legs) 430N to 436N negative side terminals 430O to 436O AC output terminals (connection points) 430P to 436P positive side terminals 430s, 431s1 to 436s1, 431s2 to 436s2 semiconductor switches 431d1 to 436d1, 431d2 to 436d2 freewheeling diodes

Claims

1. A smoothing circuit; an inverter circuit including a bridge circuit in which a plurality of switch legs, each having upper and lower arms each including a plurality of semiconductor switches connected in series, are connected in parallel, and output circuits, each having connection points of the upper and lower arms of the plurality of switch legs connected to each other, are connected in parallel for a plurality of phases, and the inverter circuit outputs a predetermined AC power based on the DC power input from the smoothing circuit; an output terminal that outputs the predetermined AC power to an outside, the inverter circuit includes: a positive-side DC bus bar connecting positive terminals of the plurality of switch legs together; a negative-side DC bus bar connecting negative terminals of the plurality of switch legs together; and a parallel-connection bus bar connecting connection points of the upper and lower arms of each of the plurality of switch legs together; the positive DC bus bar and the negative DC bus bar have a laminate structure in which they are laminated with an insulating layer interposed therebetween, the parallel connection bus bar is configured such that lengths of paths between all of the arms included in the plurality of switch legs and a junction portion at which all paths from each of the plurality of switch legs join together are approximately equal; the parallel connection bus bar is two switch legs included in the plurality of switch legs, the two switch legs being arranged side by side in one axial direction parallel to a plane on which the two switch legs are arranged, the paths extending from the two switch legs to the output terminal being joined at approximately a center position between the connection points of the two switch legs in the one axial direction, The plurality of switch legs include a plurality of combinations of the two switch legs, the parallel connection bus bar is configured such that lengths of paths between an intermediate junction portion, which joins paths from each of the two switch legs for each of the plurality of combinations toward the output terminal, and the junction portion are substantially equal to each other; The plurality of switch legs are arranged such that two sets of two switch legs are aligned in the one axial direction and arranged in two rows in another axial direction perpendicular to the one axial direction and parallel to a plane on which the two switch legs are arranged, the parallel connection bus bar is configured to be substantially symmetrical with respect to a vertical plane at the center of the two switch legs in the one axial direction, and is configured to be substantially symmetrical with respect to a vertical plane at the center of the two sets in the other axial direction, and a connection portion with wiring to the output terminal is configured to be located at a substantially central position between the four switch legs included in the two sets in the one axial direction and the other axial direction. Power conversion equipment.

2. the parallel connection bus bar is configured so that current densities in each path between all of the arms included in the plurality of switch legs and the junction are substantially equal. The power conversion device according to claim 1 .

Images