Power conversion device

Abstract

The present invention provides a technique capable of suppressing current imbalance flowing through each semiconductor switch in a power conversion device in which a plurality of switch arms each constituted by semiconductor switches equivalent to upper and lower bridge arms are connected in parallel. The power conversion device according to one embodiment of the present invention includes a U-phase positive-side DC bus (41P), a U-phase negative-side DC bus (41N), and a U-phase parallel connection bus (41O1) that connect the positive-side terminals (410P) of a plurality of switch modules (410) to each other, the negative-side terminals (410N) to each other, and the AC output terminals (410O) to each other, respectively. These buses constitute a U-phase laminated bus (41PNO) having a laminated structure laminated with an insulating layer (41I1) therebetween. The connection portion between the U-phase parallel connection bus and the U-phase output bus (41O2) is provided at a position farther from a smoothing circuit than the semiconductor switch farthest from the smoothing circuit among the plurality of switch modules.

Description

Technical Field

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

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

[0003] In Patent Document 1, there are provided a parallel connection bus bar in which each switch bridge arm is arranged in the width direction and connection points between the upper and lower bridge arms of each switch bridge arm are connected in parallel to each other, and an output bus bar connected to the parallel connection bus bar. The parallel connection bus bar is provided so as to occupy a range in the width direction where each switch bridge arm is arranged and extend in the length direction from each switch bridge arm. Further, the output bus bar is provided so as to be laminated on the parallel connection bus bar with an insulating layer interposed therebetween at the other end on the side opposite to each switch bridge arm in the length direction of the parallel connection bus bar and extend in the width direction, and one end in the width direction thereof is connected to the parallel connection bus bar.

[0004] Accordingly, in Patent Document 1, the current flowing through the parallel connection bus bar (that is, the current converging from each switch bridge arm or the current branching in each switch bridge arm) and the current flowing through the output bus bar are in opposite directions to each other, and the magnetic fields generated by each can cancel each other out. Therefore, the inductance of the power path in the width direction of the parallel connection bus bar when the currents of the respective switch bridge arms converge or branch is reduced, and thus an imbalance in the current flowing through each switch bridge arm can be suppressed.

[0005] <Prior Art Documents>

[0006] <Patent Documents>

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-055478 Summary of the Invention

[0008] <Problems to be Solved by the Invention>

[0009] However, in Patent Document 1, the current of the output bus bar corresponds to the sum of the currents of all the switch bridge arms, whereas the current flowing in the width direction at the other end of the parallel connection bus bar is only the current passing through one switch bridge arm or the sum of the currents of a part of the switch bridge arms. Therefore, there is a possibility that the magnetic field generated by the output bus bar is not canceled by the magnetic field generated by the parallel connection bus bar and remains. As a result, this magnetic field links with the current flowing in the width direction of the parallel connection bus bar, thereby generating inductance in the current path in the width direction of the parallel connection bus bar, and there is a possibility that an imbalance occurs in the current flowing through each switch bridge arm.

[0010] Therefore, in view of the above problems, an object of the present invention is to provide a technique capable of suppressing current imbalance flowing through each semiconductor switch in a power conversion device in which a plurality of switch bridge arms each composed of semiconductor switches equivalent to upper and lower bridge arms are connected in parallel.

[0011] <Means for Solving the Problem>

[0012] To achieve the above object, in one embodiment of the present invention, there is provided a power conversion device including:

[0013] A smoothing circuit;

[0014] An inverter circuit including a bridge circuit and outputting a prescribed alternating current based on direct current input from the smoothing circuit. The bridge circuit is formed by connecting in parallel a plurality of switch bridge arms each formed by connecting upper and lower bridge arms including a plurality of semiconductor switches in series, and an output circuit in which connection points of the upper and lower bridge arms of each of the plurality of switch bridge arms are connected to each other is connected in parallel with a plurality of phases; and

[0015] Output terminals for outputting the prescribed alternating current to the outside,

[0016] The inverter circuit includes: a positive-side DC bus for connecting positive-side terminals of the plurality of switch bridge arms to each other; a negative-side DC bus for connecting negative-side terminals of the plurality of switch bridge arms to each other; and a parallel connection bus for connecting connection points of the upper and lower bridge arms of each of the plurality of switch bridge arms to each other,

[0017] The positive-side DC bus, the negative-side DC bus, and the parallel connection bus have a laminated structure laminated with an insulating layer therebetween,

[0018] A connection portion of the parallel connection bus and wiring to the output terminals is provided at a position farther from the smoothing circuit than the bridge arm farthest from the smoothing circuit among all the bridge arms included in the plurality of switch bridge arms.

[0019] In addition, in other embodiments of the present invention, there is provided a power conversion device including:

[0020] A smoothing circuit;

[0021] An inverter circuit including a bridge circuit and outputting a prescribed alternating current based on direct current input from the smoothing circuit. The bridge circuit is formed by connecting in parallel a plurality of switch bridge arms each formed by connecting upper and lower bridge arms including a plurality of semiconductor switches in series, and an output circuit in which connection points of the upper and lower bridge arms of each of the plurality of switch bridge arms are connected to each other is connected in parallel with a plurality of phases; and

[0022] An output terminal that outputs the specified alternating current to the outside.

[0023] The inverter circuit includes: a positive-side DC bus that connects the positive-side terminals of the plurality of switch bridge arms to each other; a negative-side DC bus that connects the negative-side terminals of the plurality of switch bridge arms to each other; and a parallel connection bus that connects the connection points of the upper and lower bridge arms of each of the plurality of switch bridge arms to each other.

[0024] The positive-side DC bus and the negative-side DC bus have a laminated structure laminated with an insulating layer therebetween.

[0025] The parallel connection bus is configured such that the lengths of the respective paths between all of the bridge arms included in the plurality of switch bridge arms and the confluence portion where all of the paths from the plurality of switch bridge arms converge are substantially equal.

[0026] In addition, in still another embodiment of the present invention, there is provided a power conversion device including:

[0027] A smoothing circuit;

[0028] An inverter circuit that includes a bridge circuit and outputs a specified alternating current based on direct current input from the smoothing circuit. The bridge circuit is formed by connecting in parallel a plurality of switch bridge arms in which upper and lower bridge arms each including a plurality of semiconductor switches are connected in series, and an output circuit in which the connection points of the upper and lower bridge arms of each of the plurality of switch bridge arms are connected to each other is connected in parallel with a plurality of phases; and

[0029] An output terminal that outputs the specified alternating current to the outside.

[0030] The inverter circuit includes: a positive-side DC bus that connects the positive-side terminals of the plurality of switch bridge arms to each other; a negative-side DC bus that connects the negative-side terminals of the plurality of switch bridge arms to each other; and a parallel connection bus that connects the connection points of the upper and lower bridge arms of each of the plurality of switch bridge arms to each other.

[0031] The positive-side DC bus and the negative-side DC bus have a laminated structure laminated with an insulating layer therebetween.

[0032] The parallel connection bus is configured such that the lengths of the respective paths between the smoothing circuit and the confluence portion where all of the paths from the plurality of switch bridge arms converge for each of all of the bridge arms included in the plurality of switch bridge arms are substantially equal and the current density of the entire path of each of the respective paths is substantially equal over each path.

[0033] In addition, in still another embodiment of the present invention, there is provided a power conversion device including:

[0034] Smoothing circuit;

[0035] Inverter circuit, which includes a bridge circuit and outputs a specified alternating current based on the direct current input from the above smoothing circuit. The bridge circuit is formed by connecting in parallel a plurality of switching bridge arms connected in series by upper and lower bridge arms each including a plurality of semiconductor switches, and an output circuit in which connection points of the upper and lower bridge arms of each of the plurality of switching bridge arms are connected to each other is connected in parallel with a plurality of phases; and

[0036] Output terminal, which outputs the above specified alternating current to the outside,

[0037] The above inverter circuit includes: a positive-side DC bus that connects the positive-side terminals of the plurality of switching bridge arms to each other; a negative-side DC bus that connects the negative-side terminals of the plurality of switching bridge arms to each other; and a parallel connection bus that connects the connection points of the upper and lower bridge arms of each of the plurality of switching bridge arms to each other,

[0038] The above positive-side DC bus, the above negative-side DC bus, and the above parallel connection bus have a laminated structure laminated with an insulating layer therebetween,

[0039] The connection portion of the above parallel connection bus and the wiring to the above output terminal is provided at a position closer to the above smoothing circuit than the above bridge arm closest to the above smoothing circuit among all the above bridge arms included in the plurality of switching bridge arms.

[0040] <Advantages of the Invention>

[0041] According to the above embodiment, a technique can be provided that can suppress the imbalance of the current flowing through each semiconductor switch in a power conversion device in which a plurality of switching bridge arms formed by semiconductor switches equivalent to upper and lower bridge arms are connected in parallel. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a circuit diagram showing an example of a power conversion device according to the first embodiment.

[0043] Figure 2 is a structural diagram showing an example of a power conversion device according to the first embodiment.

[0044] Figure 3 is a structural diagram showing an example of a power conversion device according to the first embodiment.

[0045] Figure 4 is a diagram for explaining an example of the arrangement structure of the busbars.

[0046] Figure 5 is a diagram for explaining an example of the arrangement structure of the busbars.

[0047] Figure 6 It is a diagram for explaining an example of the configuration structure of a bus bar.

[0048] Figure 7 It is a circuit diagram showing an example of the power conversion device according to the second to fourth embodiments.

[0049] Figure 8 It is a structural diagram showing an example of the power conversion device according to the second embodiment.

[0050] Figure 9 It is a structural diagram showing an example of the power conversion device according to the second embodiment.

[0051] Figure 10 It is a diagram for explaining the path of the current flowing through each switch module.

[0052] Figure 11 It is a structural diagram showing an example of the power conversion device according to the third embodiment.

[0053] Figure 12 It is a structural diagram showing an example of the power conversion device according to the third embodiment.

[0054] Figure 13 It is a structural diagram showing an example of the power conversion device according to the fourth embodiment.

[0055] Figure 14 It is a structural diagram showing an example of the power conversion device according to the fourth embodiment. Detailed Embodiments

[0056] Hereinafter, the embodiments will be described with reference to the drawings.

[0057] [First Embodiment]

[0058] First, with reference to Figures 1 - 6 , the first embodiment will be described.

[0059] <Overview of the Power Conversion Device>

[0060] Figure 1 It is a circuit diagram showing an example of the power conversion device 1 according to the first embodiment.

[0061] The power conversion device 1 uses three-phase alternating current input from a specified external power source (for example, a commercial power supply system), generates a specified three-phase alternating current, and supplies the generated three-phase alternating current to a specified load device (for example, a motor).

[0062] As Figure 1As shown, the power conversion device 1 includes a rectifier circuit 10, a smoothing circuit 20, a fuse 30, and an inverter circuit 40.

[0063] The rectifier circuit 10 rectifies the three-phase alternating current of the R phase, S phase, and T phase input from an external power source via the input terminal 11 and outputs a specified direct current to the smoothing circuit 20.

[0064] The input terminal 11 includes an R-phase input terminal 111 for inputting the power of the R phase, an S-phase input terminal 112 for inputting the power of the S phase, and a T-phase input terminal 113 for inputting the power of the T phase.

[0065] As Figure 1 shown, 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.

[0066] The smoothing circuit 20 is used to smooth the direct current output from the rectifier circuit 10 and the direct current regenerated from the inverter circuit 40.

[0067] The smoothing circuit 20 includes a positive-side bus bar 20P, a negative-side bus bar 20N, and a smoothing capacitor 21.

[0068] The positive-side bus bar 20P is a flat plate-shaped component made of a material with relatively high conductivity (for example, copper, aluminum, etc.). Hereinafter, the same applies to the negative-side bus bar 20N, the U-phase positive-side DC bus bar 41P, the U-phase negative-side DC bus bar 41N, the V-phase positive-side DC bus bar 42P, the V-phase negative-side DC bus bar 42N, the W-phase positive-side DC bus bar 43P, and the W-phase negative-side DC bus bar 43N described later.

[0069] The positive-side bus bar 20P is connected to the positive-side output terminal of the rectifier circuit 10 and the positive-side input terminal of the inverter circuit 40, respectively.

[0070] The negative-side bus bar 20N is connected to the negative-side output terminal of the rectifier circuit 10 and the negative-side DC input terminal of the inverter circuit 40.

[0071] The smoothing capacitor 21 is disposed in parallel with the rectifier circuit 10 and the inverter circuit 40 in the power path connecting the positive-side bus bar 20P and the negative-side bus bar 20N. The smoothing capacitor 21 appropriately smooths the direct current output from the rectifier circuit 10 and the inverter circuit 40 while repeating charging and discharging.

[0072] The smoothing capacitor 21 may be one, or a plurality of smoothing capacitors 21 may be connected in parallel (refer to Figure 2 , Figure 3 ).

[0073] 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.

[0074] 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, thereby protecting the power conversion device 1 (inverter circuit 40) from damage caused by an overcurrent accompanying an overload, a short circuit, or the like.

[0075] The inverter circuit 40 generates three-phase alternating current of U-phase, V-phase, and W-phase from the direct current 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 for outputting the alternating current of the U-phase to the outside, a V-phase output terminal 42T for outputting the alternating current of the V-phase to the outside, and a W-phase output terminal 43T for outputting the alternating current of the W-phase to the outside.

[0076] 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 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.

[0077] 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, switching modules 411 to 414, and a U-phase AC bus bar 41O. Hereinafter, in the first embodiment, the switching modules 411 to 414 may be collectively referred to as the "switching module 410", or any one of the switching modules 411 to 414 may be individually referred to as the "switching module 410".

[0078] 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.

[0079] The U-phase negative electrode side DC bus bar 41N is connected to the negative electrode side bus bar 20N of the smoothing circuit 20.

[0080] The switching modules 411 to 414 (an example of a switching bridge arm) are connected in parallel between the U-phase positive electrode side DC bus bar 41P and the U-phase negative electrode side DC bus bar 41N.

[0081] The switching module 411 includes semiconductor switches 411s1 and 411s2 corresponding to the upper and lower bridge arms, freewheeling diodes 411d1 and 411d2, a positive electrode side terminal 411P, a negative electrode side terminal 411N, and an AC output terminal 411O.

[0082] The switch module 412 includes semiconductor switches 412s1 and 412s2 equivalent to the upper and lower bridge arms, freewheeling diodes 412d1 and 412d2, a positive-side terminal 412P, a negative-side terminal 412N, and an AC output terminal 412O.

[0083] The switch module 413 includes semiconductor switches 413s1 and 413s2 equivalent to the upper and lower bridge arms, freewheeling diodes 413d1 and 413d2, a positive-side terminal 413P, a negative-side terminal 413N, and an AC output terminal 413O.

[0084] The switch module 414 includes semiconductor switches 414s1 and 414s2 equivalent to the upper and lower bridge arms, freewheeling diodes 414d1 and 414d2, a positive-side terminal 414P, a negative-side terminal 414N, and an AC output terminal 414O.

[0085] Hereinafter, in the first embodiment, the semiconductor switches 411s1, 411s2, 412s1, 412s2, 413s1, 413s2, 414s1, and 414s2 may be collectively referred to as "semiconductor switch 410s", or any one of them may be individually referred to as "semiconductor switch 410s". Further, in the first embodiment, the components corresponding to the positive-side terminals 411P to 414P of the above-mentioned "switch module 410" may be referred to as "positive-side terminal 410P". Further, in the first embodiment, the components corresponding to the negative-side terminals 411N to 414N of the above-mentioned "switch module 410" may be referred to as "negative-side terminal 410N". Further, 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".

[0086] Since the switch modules 411 to 414 have the same components and are composed of the same circuit, the switch module 411 will be taken as an example for description, and the descriptions of the switch modules 412 to 414 will be omitted.

[0087] The semiconductor switches 411s1 and 411s2 (an example of the upper and lower bridge arms) are arranged on the power path connecting the positive-side terminal 411P and the negative-side terminal 411N, and are connected in series with each other. The semiconductor switches 411s1 and 411s2 are, for example, IGBTs (Insulated Gate Bipolar Transistors).

[0088] The semiconductor switch 411s1 is equivalent to the upper bridge arm of the switch bridge arm and is connected to the positive-side terminal 411P.

[0089] The semiconductor switch 411s2 is equivalent to the lower bridge arm of the switch bridge arm and is connected to the negative-side terminal 411N.

[0090] The freewheeling diodes 411d1 and 411d2 are connected in parallel with the respective semiconductor switches 411s1 and 411s2.

[0091] The positive-side terminal 411P is connected to the positive-side DC bus 41P of the U phase.

[0092] The negative-side terminal 411N is connected to the negative-side DC bus 41N of the U phase.

[0093] The AC output terminal 411O (an example of the connection point of the upper and lower bridge arms) is led out from the connection point (midpoint) between the semiconductor switches 411s1 and 411s2.

[0094] One end of the U-phase AC bus 41O connects the AC output terminals 411O to 414O of the respective switching modules 411 to 414 to each other, and the other end thereof is connected to the U-phase output terminal 41T. Thus, the inverter circuit 40 can output the U-phase alternating current output from the switching modules 411 to 414 to the outside from the U-phase output terminal 41T.

[0095] The V-phase circuit 42 includes a V-phase positive-side DC bus 42P, a V-phase negative-side DC bus 42N, switching modules 421 to 424, and a V-phase AC bus 42O. Hereinafter, in the first embodiment, the switching modules 421 to 424 may be collectively referred to as the "switching module 420", or any one of the switching modules 421 to 424 may be individually referred to as the "switching module 420".

[0096] The V-phase positive-side DC bus 42P is connected to the positive-side bus 20P of the smoothing circuit 20 via the fuse 30.

[0097] The V-phase negative-side DC bus 42N is connected to the negative-side bus 20N of the smoothing circuit 20.

[0098] The switching modules 421 to 424 are connected in parallel between the V-phase positive-side DC bus 42P and the V-phase negative-side DC bus 42N.

[0099] The switching module 421 includes semiconductor switches 421s1 and 421s2 corresponding to the upper and lower bridge arms, freewheeling diodes 421d1 and 421d2, a positive-side terminal 421P, a negative-side terminal 421N, and an AC output terminal 421O.

[0100] The switching module 422 includes semiconductor switches 422s1 and 422s2 corresponding to the upper and lower bridge arms, freewheeling diodes 422d1 and 422d2, a positive-side terminal 422P, a negative-side terminal 422N, and an AC output terminal 422O.

[0101] The switching module 423 includes semiconductor switches 423s1 and 423s2 equivalent to upper and lower bridge arms, freewheeling diodes 423d1 and 423d2, a positive-side terminal 423P, a negative-side terminal 423N, and an AC output terminal 423O.

[0102] The switching module 424 includes semiconductor switches 424s1 and 424s2 equivalent to upper and lower bridge arms, freewheeling diodes 424d1 and 424d2, a positive-side terminal 424P, a negative-side terminal 424N, and an AC output terminal 424O.

[0103] Hereinafter, in the first embodiment, the semiconductor switches 421s1, 421s2, 422s1, 422s2, 423s1, 423s2, 424s1, and 424s2 may be collectively referred to as "semiconductor switch 420s", or any one of them may be individually referred to as "semiconductor switch 420s". Further, in the first embodiment, the components corresponding to the positive-side terminals 421P to 424P of the above-mentioned "switching module 420" may be referred to as "positive-side terminal 420P". Further, in the first embodiment, the components corresponding to the negative-side terminals 421N to 424N of the above-mentioned "switching module 420" may be referred to as "negative-side terminal 420N". Further, in the first embodiment, the components corresponding to the AC output terminals 421O to 424O of the above-mentioned "switching module 420" may be referred to as "AC output terminal 420O".

[0104] Since the switching modules 421 to 424 have the same components and the same circuit configuration, the switching module 421 will be described as a representative, and the descriptions of the switching modules 422 to 424 will be omitted.

[0105] The semiconductor switches 421s1 and 421s2 (an example of upper and lower bridge arms) are arranged on the power path connecting the positive-side terminal 421P and the negative-side terminal 421N, and are connected in series with each other.

[0106] The semiconductor switch 421s1 is equivalent to the upper bridge arm of the switch bridge arm and is connected to the positive-side terminal 421P.

[0107] The semiconductor switch 421s2 is equivalent to the lower bridge arm of the switch bridge arm and is connected to the negative-side terminal 421N.

[0108] The freewheeling diodes 421d1 and 421d2 are connected in parallel with the respective semiconductor switches 421s1 and 421s2.

[0109] The positive-side terminal 421P is connected to the V-phase positive-side DC bus 42P.

[0110] The negative-side terminal 421N is connected to the V-phase negative-side DC bus 42N.

[0111] The AC output terminal 421O (an example of the connection point of the upper and lower bridge arms) is led out from the connection point (midpoint) between the semiconductor switches 421s1 and 421s2.

[0112] The V-phase AC bus 42O connects the AC output terminals 421O to 424O of the respective switch modules 421 to 424 to each other at one end thereof, and is connected to the V-phase output terminal 42T at the other end thereof. Thus, the inverter circuit 40 can output the V-phase alternating current output from the switch modules 421 to 424 to the outside from the V-phase output terminal 42T.

[0113] The W-phase circuit 43 includes a W-phase positive-side DC bus 43P, a W-phase negative-side DC bus 43N, switch modules 431 to 434, and a W-phase AC bus 43O. Hereinafter, in the first embodiment, the switch modules 431 to 434 may be collectively referred to as "switch module 430", or any one of the switch modules 431 to 434 may be individually referred to as "switch module 430".

[0114] The W-phase positive-side DC bus 43P is connected to the positive-side bus 20P of the smoothing circuit 20 via a fuse 30.

[0115] The W-phase negative-side DC bus 43N is connected to the negative-side bus 20N of the smoothing circuit 20.

[0116] The switch modules 431 to 434 are connected in parallel between the W-phase positive-side DC bus 43P and the W-phase negative-side DC bus 43N.

[0117] The switch module 431 includes semiconductor switches 431s1 and 431s2 corresponding to the upper and lower bridge arms, freewheeling diodes 431d1 and 431d2, a positive-side terminal 431P, a negative-side terminal 431N, and an AC output terminal 431O.

[0118] The switch module 432 includes semiconductor switches 432s1 and 432s2 corresponding to the upper and lower bridge arms, freewheeling diodes 432d1 and 432d2, a positive-side terminal 432P, a negative-side terminal 432N, and an AC output terminal 432O.

[0119] The switch module 433 includes semiconductor switches 433s1 and 433s2 corresponding to the upper and lower bridge arms, freewheeling diodes 433d1 and 433d2, a positive-side terminal 433P, a negative-side terminal 433N, and an AC output terminal 433O.

[0120] The switching module 434 includes semiconductor switches 434s1 and 434s2 equivalent to upper and lower bridge arms, freewheeling diodes 434d1 and 434d2, a positive-side terminal 434P, a negative-side terminal 434N, and an AC output terminal 434O.

[0121] Hereinafter, in the first embodiment, the semiconductor switches 431s1, 431s2, 432s1, 432s2, 433s1, 433s2, 434s1, and 434s2 may be collectively referred to as "semiconductor switch 430s", or any one of them may be individually referred to as "semiconductor switch 430s". Further, in the first embodiment, the elements corresponding to the positive-side terminals 431P to 434P of the above-mentioned "switching module 430" may be referred to as "positive-side terminal 430P". Further, in the first embodiment, the elements corresponding to the negative-side terminals 431N to 434N of the above-mentioned "switching module 430" may be referred to as "negative-side terminal 430N". Further, in the first embodiment, the elements corresponding to the AC output terminals 431O to 434O of the above-mentioned "switching module 430" may be referred to as "AC output terminal 430O".

[0122] Since the switching modules 431 to 434 have the same constituent elements and the same circuit configuration, the switching module 431 will be described as a representative, and the description of the switching modules 432 to 434 will be omitted.

[0123] The semiconductor switches 431s1 and 431s2 (an example of upper and lower bridge arms) are arranged on the power path connecting the positive-side terminal 431P and the negative-side terminal 431N and are connected in series with each other.

[0124] The semiconductor switch 431s1 corresponds to the upper bridge arm of the switch bridge arm and is connected to the positive-side terminal 431P.

[0125] The semiconductor switch 431s2 corresponds to the lower bridge arm of the switch bridge arm and is connected to the negative-side terminal 431N.

[0126] The freewheeling diodes 431d1 and 431d2 are connected in parallel with the respective semiconductor switches 431s1 and 431s2.

[0127] The positive-side terminal 431P is connected to the W-phase positive-side DC bus 43P.

[0128] The negative-side terminal 431N is connected to the W-phase negative-side DC bus 43N.

[0129] The AC output terminal 431O (an example of the connection point of the upper and lower bridge arms) is led out from the connection point (midpoint) between the semiconductor switches 431s1 and 431s2.

[0130] The W-phase AC bus 43O connects the AC output terminals 431O to 434O of the respective switching modules 431 to 434 to each other at one end thereof, and is connected to the W-phase output terminal 43T at the other end thereof. Thus, the inverter circuit 40 can output the W-phase alternating current output from the switching modules 431 to 434 to the outside from the W-phase output terminal 43T.

[0131] <Structure of the power conversion device>

[0132] Figure 2 , Figure 3 is a structural diagram showing an example of the power conversion device 1 of the first embodiment. Specifically, Figure 2 is a perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed, Figure 3 is an exploded perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed, the output terminal 40T is removed, and it is moved upward. Figures 4 - 6 is a diagram for explaining an example of the arrangement structure of the busbars. Specifically, Figure 4 is an exploded perspective view schematically showing the components of the busbars disassembled, Figure 5 is a perspective view showing the completed state after assembling the components of the Figure 4 busbars, Figure 6 is a side view schematically showing an example of the arrangement structure of the busbars.

[0133] Note that in Figure 4 , Figure 5 , for convenience, the laminated busbar 20PN, the U-phase laminated busbar 41PN, the V-phase laminated busbar 42PN, and the W-phase laminated busbar 43PN are depicted as an integrated component. Further, in Figure 4 , for convenience, the positive-side busbar 20P of the smoothing circuit 20, and the U-phase positive-side DC busbar 41P, the V-phase positive-side DC busbar 42P, and the W-phase positive-side DC busbar 43P of the inverter circuit 40 are depicted as an integrated component. Similarly, in Figure 4 , for convenience, the negative-side busbar 20N of the smoothing circuit 20, and the U-phase negative-side DC busbar 41N, the V-phase negative-side DC busbar 42N, and the W-phase negative-side DC busbar 43N of the inverter circuit 40 are depicted as an integrated component. Similarly, in Figure 4 , the insulating layers 20I1, 41I1, 42I1, 43I1 are depicted as an integrated component. Similarly, in Figure 4 , the insulating layers 20I2, 41I2, 42I2, 43I2 are depicted as an integrated component. Further, in Figure 4 , Figure 5In this case, for simplicity, only a part (4) of all the smoothing capacitors 21 of the smoothing circuit 20 is depicted as a representative. Similarly, in Figure 4 , Figure 5 In this case, for simplicity, only a part (1) of all the switching modules 410 of the U-phase circuit 41 is depicted as a representative. Similarly, in Figure 4 , Figure 5 In this case, for simplicity, only a part (1) of the switching modules 420 included in the V-phase circuit 42 is depicted as a representative. Similarly, in Figure 4 , Figure 5 In this case, for simplicity, only a part (1) of the switching modules 430 included in the W-phase circuit 43 is depicted as a representative. In addition, in Figure 6 For convenience, the depiction of the insulating layers 20I1, 20I2, 41I1, 41I2, 42I1, 42I2, 43I1, and 43I2 is omitted.

[0134] As Figure 2 , Figure 3 shown, the various components of the power conversion device 1 are accommodated in a substantially box-shaped housing 1H having a substantially rectangular shape in all views of top, side, and front. "Substantially" is intended to allow for manufacturing errors, etc., and will be used in the same sense hereinafter.

[0135] Hereinafter, the length 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 Figures 2 - 6 ).

[0136] As Figure 2 , Figure 3 shown, the smoothing circuit 20, the fuse 30, and the inverter circuit 40 are arranged in sequence from one end to the other end in the length direction (i.e., in the positive X-axis direction) inside the housing 1H.

[0137] In addition, the output terminal 40T is arranged at the central portion in the length 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.

[0138] As described above, the output terminal 40T includes 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 sequence from one end to the central portion in the short side direction (i.e., in the positive Y-axis direction) inside the housing 1H.

[0139] In this example, the smoothing circuit 20 includes 24 smoothing capacitors 21.

[0140] The smoothing capacitor 21 has a substantially cylindrical shape and is placed on the bottom surface of the housing 1H with its axis in the vertical direction. In addition, a positive-side terminal 21P and a negative-side terminal 21N are provided on the end face (upper end face) opposite to the placement surface of the smoothing capacitor 21.

[0141] Specifically, as Figure 2 , Figure 3 shown, four smoothing capacitors 21 are arranged and configured in the X-axis direction, and six smoothing capacitors 21 are arranged and configured in the Y-axis direction.

[0142] On the upper end face of the smoothing capacitor 21, the laminated bus bar 20PN is arranged in a manner substantially parallel to the X-axis direction and the Y-axis direction.

[0143] 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.

[0144] As Figure 4 , Figure 5 shown, the laminated bus bar 20PN is formed by laminating a positive-side bus bar 20P and a negative-side bus bar 20N with an insulating layer 20I1 therebetween. Specifically, the laminated bus bar 20PN has a four-layer laminated structure in which the negative-side bus bar 20N is arranged in the lowermost layer, the insulating layer 20I1 is arranged above the bus bar 20N, the positive-side bus bar 20P is arranged above the insulating layer 20I1, and the insulating layer 20I2 is arranged in the uppermost layer.

[0145] As Figures 4 - 6 shown, on the lowermost negative-side bus bar 20N, there are provided relatively small through holes for bolt-fastening to the negative-side terminal 21N of the smoothing capacitor 21. Thus, the negative-side terminal 21N of the smoothing capacitor 21 can be directly connected to the negative-side bus bar 20N. In addition, on the negative-side bus bar 20N, there are provided relatively large through holes for exposing the positive-side terminal 21P when viewed from above. Thus, the positive-side bus bar 20P in the layer above the negative-side bus bar 20N can be connected to the positive-side terminal 21P.

[0146] As Figure 4 , Figure 5 , on the insulating layer 20I1 adjacent above the negative-side bus bar 20N, there are provided relatively large through holes for exposing the positive-side terminal 21P and the negative-side terminal 21N of the smoothing capacitor 21 (i.e., the through holes for fastening the negative-side bus bar 20N) when viewed from above.

[0147] As Figures 4 - 6As shown, on the positive-side bus bar 20P adjacent to the insulating layer 20I1, there is provided a relatively small through-hole for bolting and fastening the positive-side terminal 21P of the smoothing capacitor 21. Thereby, the positive-side terminal 21P of the smoothing capacitor 21 can be directly connected to the positive-side bus bar 20P. Further, on the positive-side bus bar 20P, there is provided a relatively large through-hole for exposing the negative-side terminal 21N of the smoothing capacitor 21 (i.e., the through-hole for fastening the negative-side bus bar 20N) in a top view. Thereby, the operator can access the through-hole for fastening the negative-side bus bar 20N located in a layer below the positive-side bus bar 20P.

[0148] As Figure 4 , Figure 5 shown, on the uppermost insulating layer 20I2, there are provided relatively large through-holes for exposing the positive-side terminal 21P (i.e., the through-hole for fastening the positive-side bus bar 20P) and the negative-side terminal 21N (i.e., the through-hole for fastening the negative-side bus bar 20N) of the smoothing capacitor 21 in a top view.

[0149] The positive-side bus bar 20P and the negative-side bus bar 20N of the laminated bus bar 20PN have, for example, substantially the same thickness. Thereby, the current densities of the positive-side bus bar 20P and the negative-side bus bar 20N are substantially equal.

[0150] Further, the laminated bus bar 20PN can be arranged in the housing 1H such that the overlapping area of the positive-side bus bar 20P and the negative-side bus bar 20N is relatively large (preferably maximized). Further, the thickness of the insulating layer 20I1 is set such that while ensuring the insulation between the positive-side bus bar 20P and the negative-side bus bar 20N, the distance therebetween is relatively small. Thereby, in terms of space, the current paths flowing in opposite directions can be made close. Thereby, at least a part of the magnetic field generated by the current in the positive-side bus bar 20P and the magnetic field generated by the current in the negative-side bus bar 20N are cancelled, so that the inductances of the positive-side bus bar 20P and the negative-side bus bar 20N can be reduced. Further, as described above, when the current densities are substantially equal, the magnitudes of the magnetic fields generated by the current in the positive-side bus bar 20P and the current in the negative-side bus bar 20N are substantially equal, so that the generated magnetic fields can be substantially cancelled. Therefore, the inductance of the positive-side bus bar 20P and the negative-side bus bar 20N can be further suppressed. Thereby, along with the reduction of the inductances of the positive-side bus bar 20P and the negative-side bus bar 20N, the surge voltage of the power conversion device 1 can be suppressed.

[0151] 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.

[0152] As Figure 2 , Figure 3As shown, the U-phase circuit 41, the V-phase circuit 42, and the W-phase circuit 43 are arranged in sequence in the Y-axis direction from the end portion in the negative Y-axis direction toward the end portion in the positive Y-axis direction.

[0153] The U-phase circuit 41 includes four switching modules 410 (i.e., corresponding to the above-described switching modules 411 to 414).

[0154] The four switching modules 410 are arranged in two rows in the Y-axis direction with two arranged in the X-axis direction. In addition, the four switching modules 410 are arranged above other components (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.) placed on the bottom surface of the housing 1H. Thereby, the difference in the upper end position of the smoothing capacitor 21 having a relatively large size in the Z-axis direction can be made relatively small. Thereby, the positions of the positive-side bus bar 20P and the negative-side bus bar 20N in the Z-axis direction can be made relatively close to the positions of the U-phase positive-side DC bus bar 41P and the U-phase negative-side DC bus bar 41N in the Z-axis direction.

[0155] As Figure 4 , Figure 5 shown, the switching module 410 has a box shape, and has a notch for fastening and a support surface for bolts at its corners when viewed from above.

[0156] The switching module 410 is arranged such that its length direction when viewed from above is along the approximate X-axis direction. In the switching module 410, along its length direction (i.e., the X-axis direction), the AC output terminal 410O, the negative-side terminal 410N, and the positive-side terminal 410P are arranged in sequence in the order of approaching the smoothing circuit 20 (smoothing capacitor 21).

[0157] It should be noted that in the U-phase circuit 41, a switching bridge arm of a different method from the method in which a series connection body of two semiconductor switches 410s is previously accommodated in the housing like the switching module 410 can be applied. Hereinafter, the same applies to the switching module 420 of the V-phase circuit 42 and the switching module 430 of the W-phase circuit 43, and the same also applies to the second to fourth embodiments described later.

[0158] At the upper end of the switch module 410, the U-phase laminated busbar 41PN is arranged in a manner substantially parallel to the X-axis direction and the Y-axis direction. Specifically, the U-phase laminated busbar 41PN is configured to be integrally connected to the V-phase laminated busbar 42PN and the W-phase laminated busbar 43PN described later. That is, at the upper end of the switch module 410, the laminated busbar 40PN including the U-phase laminated busbar 41PN, the V-phase laminated busbar 42PN, and the W-phase laminated busbar 43PN is arranged in a manner substantially parallel to the X-axis direction and the Y-axis direction. Hereinafter, the same applies to the second to fourth embodiments described later.

[0159] The U-phase laminated busbar 41PN is arranged so as to cover a range of four switch modules 410 in the X-axis direction and the Y-axis direction.

[0160] As Figure 4 , Figure 5 shown, the U-phase laminated busbar 41PN is formed by laminating the U-phase positive-side DC busbar 41P and the U-phase negative-side DC busbar 41N with an insulating layer 41I1 therebetween. Specifically, the U-phase laminated busbar 41PN has a four-layer laminated structure in which the U-phase negative-side DC busbar 41N is arranged at its lowermost layer, the insulating layer 41I1 is arranged above the U-phase negative-side DC busbar 41N, the U-phase positive-side DC busbar 41P is arranged above the insulating layer 41I1, and the insulating layer 41I2 is arranged at the uppermost layer.

[0161] The U-phase positive-side DC busbar 41P is configured to be integrally connected to the V-phase positive-side DC busbar 42P and the W-phase positive-side DC busbar 43P described later (for example, as an integral plate-like component). That is, as Figure 6 shown, the laminated busbar 40PN includes a positive-side DC busbar 40P configured to include the U-phase positive-side DC busbar 41P, the V-phase positive-side DC busbar 42P, and the W-phase positive-side DC busbar 43P. Hereinafter, the same applies to the second to fourth embodiments described later.

[0162] The U-phase negative-side DC busbar 41N is configured to be integrally connected to the V-phase negative-side DC busbar 42N and the W-phase negative-side DC busbar 43N described later (for example, as an integral plate-like component). That is, as Figure 6 shown, the laminated busbar 40PN includes a negative-side DC busbar 40N configured to include the U-phase negative-side DC busbar 41N, the V-phase negative-side DC busbar 42N, and the W-phase negative-side DC busbar 43N. Hereinafter, the same applies to the second to fourth embodiments described later.

[0163] The insulating layer 41I1 can be formed in a manner that is integrally connected to the insulating layer 42I1 and the insulating layer 43I1 to be described later (for example, as an integral plate-like component). Similarly, the insulating layer 42I2 can be formed in a manner that is integrally connected to the insulating layer 42I2 and the insulating layer 43I2 to be described later (for example, as an integral plate-like component). The same applies to the second to fourth embodiments to be described later.

[0164] As Figures 4 - 6 shown, in the U-phase negative-side DC bus 41N of the lowermost layer, there are provided relatively small through-holes for bolt-fastening to the negative-side terminal 410N of the switch module 410. Thus, the negative-side terminal 410N of the switch module 410 can be directly connected to the U-phase negative-side DC bus 41N. In addition, in the U-phase negative-side DC bus 41N, there is provided a relatively large substantially rectangular through-hole for exposing the positive-side terminal 410P in a top view. Thus, the U-phase positive-side DC bus 41P in the layer above the U-phase negative-side DC bus 41N can be connected to the positive-side terminal 410P. In addition, in the U-phase negative-side DC bus 41N, there is provided a relatively large substantially rectangular through-hole for exposing the AC output terminal 410O in a top view. Thus, the U-phase AC bus 41O in the layer above the U-phase negative-side DC bus 41N can be connected to the AC output terminal 410O.

[0165] As Figure 4 、 Figure 5 shown, in the insulating layer 41I1 adjacent above the U-phase negative-side DC bus 41N, there is provided a relatively large substantially rectangular through-hole corresponding to the switch module 410. Thus, the positive-side terminal 410P, the negative-side terminal 410N (i.e., the through-hole for fastening the U-phase negative-side DC bus 41N), and the AC output terminal 410O can be exposed in a top view.

[0166] As Figures 4 - 6 shown, in the U-phase positive-side DC bus 41P adjacent above the insulating layer 41I1, there are provided relatively small through-holes for bolt-fastening to the positive-side terminal 410P of the switch module 410. Thus, the positive-side terminal 410P of the switch module 410 can be directly connected to the U-phase positive-side DC bus 41P. In addition, in the U-phase positive-side DC bus 41P, there are provided relatively large through-holes 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 41N) and the AC output terminal 410O in a top view. Thus, the operator can reach the through-hole for fastening the U-phase negative-side DC bus 41N and the AC output terminal 410O in the layer below the U-phase positive-side DC bus 41P.

[0167] As Figure 4, Figure 5 As shown, in the uppermost insulating layer 41I2, there is a relatively large rectangular through-hole corresponding to the switch module 410. Thus, the positive electrode side terminal 410P of the switch module 410 (i.e., the through-hole for fastening the U-phase positive electrode side DC bus 41P), the negative electrode side terminal 410N (i.e., the through-hole for fastening the U-phase negative electrode side DC bus 41N), and the AC output terminal 410O are exposed in a top view.

[0168] The U-phase positive electrode side DC bus 41P and the U-phase negative electrode side DC bus 41N of the U-phase laminated bus 41PN have, for example, substantially the same thickness. Thus, the current densities of the U-phase positive electrode side DC bus 41P and the U-phase negative electrode side DC bus 41N are substantially equal.

[0169] As Figures 2 - 6 shown, the U-phase AC bus 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 41O includes a U-phase parallel connection bus 41O1 and a U-phase output bus 41O2.

[0170] The U-phase parallel connection bus 41O1 is a component for parallely connecting the AC output terminals 410O of the four switch modules 410 in the overall structure of the U-phase AC bus 41O. Specifically, the U-phase parallel connection bus 41O1 is a component for combining the power paths from the respective AC output terminals 410O of the four switch modules 410 toward the U-phase output terminal 41T.

[0171] As Figure 2 , Figure 3 shown, the U-phase parallel connection bus 41O1 is configured to be mirror-symmetric with respect to the vertical plane with respect to the X-axis at the central position between the two switch modules 410 arranged in the X-axis direction. In addition, the U-phase parallel connection bus 41O1 is configured to be mirror-symmetric with respect to the vertical plane with respect to the Y-axis at the central position between the two columns of switch modules 410 arranged in the Y-axis direction. And the U-phase parallel connection bus 41O1 is connected to the U-phase output bus 41O2 at the part 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. Thus, the paths from the respective AC output terminals 410O of the four switch modules 410 toward the U-phase output terminal 41T can have substantially equal path lengths until they merge. In addition, the current densities of each path from the respective AC output terminals 410O of the four switch modules 410 toward the U-phase output terminal 41T can be substantially equal. Therefore, the inductances of the power paths between the four switch modules 410 and the U-phase output terminal 41T can be substantially equal.

[0172] Specifically, the bus bar 41O1 for U-phase parallel connection includes two legs 41O1a and a connecting portion 41O1b.

[0173] The two legs 41O1a each have a flat plate shape that is substantially parallel in the X-axis direction and the Z-axis direction. The two legs 41O1a are respectively connected to the AC output terminals 410O of two switch modules 410 arranged in two columns in the Y-axis direction and arranged in the X-axis direction. The two legs 41O1a are configured to be face-symmetrical 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 as a reference. Specifically, the leg 41O1a includes two supporting faces, two lower legs, an intermediate leg, and an upper leg. The two supporting faces have a substantially rectangular shape when viewed from above, 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 the respective two supporting faces. The intermediate leg connects the two lower legs in a manner extending in the X-axis direction. The upper leg is provided so as to extend from the upper end of the intermediate leg and the central portion in the X-axis direction. Thereby, the leg 41O1a can cause the paths from the AC output terminals 410O of the two switch modules 410 to merge at substantially the same distance. In addition, the leg 41O1a makes the cross-sectional areas of the paths from the AC output terminals 410O of the two switch modules 410 substantially the same, so that the current density can be substantially the same. In addition, the two legs 41O1a are configured to be face-symmetrical 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 as a reference. Thereby, the two legs 41O1a can make the paths from the two switch modules 410 until merging be substantially the same distance.

[0174] The connecting portion 41O1b has a flat plate shape substantially parallel to the X-axis direction and the Y-axis direction, and is connected to two leg portions 41O1a arranged in the Y-axis direction. Specifically, the connecting portion 41O1b has a substantially rectangular shape in a top view, and connects the upper leg portions of the two leg portions 41O1a in a manner extending in the Y-axis direction. In addition, the connecting portion 41O1b is configured to be face-symmetrical with respect to the vertical plane with respect to the Y-axis at a substantially central position between the two leg portions 41O1a in the Y-axis direction, that is, at a substantially central position between the AC output terminals 410O of the two (two columns) switch modules 410 arranged in the Y-axis direction. In addition, the connecting portion 41O1b is connected to the U-phase output bus bar 41O2 at a substantially central position between the two leg portions 41O1a in the Y-axis direction. Thus, the U-phase parallel connection bus bar 41O1 can make the paths from the four switch modules 410 merge in a way that the lengths of every two paths are equal, and can make the current density of each path the same.

[0175] The U-phase output bus bar 41O2 is arranged to extend from the central portion in the Y-axis direction of the connecting portion 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.

[0176] The V-phase circuit 42 also includes four switch modules 420, similar to the U-phase circuit 41.

[0177] Since the configuration 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.

[0178] As Figure 4 、 Figure 5 , the external shape of the switch module 420 is the same as that of the switch module 410.

[0179] The switch modules 420 are arranged such that the length direction in a top view is along the substantially X-axis direction. In the switch module 420, along its length 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 sequence in the order approaching the smoothing circuit 20 (smoothing capacitor 21).

[0180] At the upper end portion 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.

[0181] The V-phase laminated bus bar 42PN is arranged to cover the range of the four switch modules 420 in the X-axis direction and the Y-axis direction.

[0182] As Figure 4 、 Figure 5As shown, the V-phase laminated busbar 42PN is formed by laminating the V-phase positive-side DC busbar 42P and the V-phase negative-side DC busbar 42N with an insulating layer 42I1 therebetween. Specifically, the V-phase laminated busbar 42PN has a four-layer laminated structure in which the V-phase negative-side DC busbar 42N is disposed at the lowermost layer, the insulating layer 42I1 is disposed above the V-phase negative-side DC busbar 42N, the V-phase positive-side DC busbar 42P is disposed above the insulating layer 42I1, and the insulating layer 42I2 is disposed at the uppermost layer.

[0183] As described above, the V-phase positive-side DC busbar 42P is configured to be integrally connected to the U-phase positive-side DC busbar 41P and the W-phase positive-side DC busbar 43P, which will be described later.

[0184] As described above, the V-phase negative-side DC busbar 42N is configured to be integrally connected to the U-phase negative-side DC busbar 41N and the W-phase negative-side DC busbar 43N, which will be described later.

[0185] As described above, the insulating layer 42I1 can be configured to be integrally connected to the insulating layer 41I1 and the insulating layer 43I1, which will be described later. Similarly, as described above, the insulating layer 42I2 can be configured to be integrally connected to the insulating layer 41I2 and the insulating layer 43I2, which will be described later.

[0186] 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.

[0187] As Figures 2 - 6 shown, the V-phase AC busbar 42O connects between the AC output terminal 420O of the switch module 420 and the V-phase output terminal 42T. The V-phase AC busbar 42O includes a V-phase parallel connection busbar 42O1 and a V-phase output busbar 42O2.

[0188] Since the configuration and structure of the V-phase AC busbar 42O are the same as those of the U-phase AC busbar 41O, the description thereof is omitted.

[0189] The W-phase circuit 43 includes four switch modules 430, similarly to the U-phase circuit 41.

[0190] Since the configuration 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.

[0191] As Figure 4 、 Figure 5 shown, the external shape of the switch module 430 is the same as that of the switch module 410.

[0192] The switch module 430 is arranged in a manner such that its length direction in a top view is along the approximate X-axis direction. In the switch module 430, along its length direction (i.e., the X-axis direction), the AC output terminal 430O, the negative-side terminal 430N, and the positive-side terminal 430P are arranged in sequence in the order approaching the smoothing circuit 20 (smoothing capacitor 21).

[0193] At the upper end portion of the switch module 430, the W-phase laminated bus bar 43PN is arranged in a manner substantially parallel to the X-axis direction and the Y-axis direction.

[0194] The W-phase laminated bus bar 43PN is arranged over a range covering four switch modules 430 in the X-axis direction and the Y-axis direction.

[0195] As Figure 4 、 Figure 5 shown, the W-phase laminated bus bar 43PN is formed by laminating the W-phase positive-side DC bus bar 43P and the W-phase negative-side DC bus bar 43N with an insulating layer 43I1 therebetween. Specifically, the W-phase laminated bus bar 43PN has a four-layer laminated structure in which the W-phase negative-side DC bus bar 43N is arranged in the lowermost layer, the insulating layer 43I1 is arranged above the W-phase negative-side DC bus bar 43N, the W-phase positive-side DC bus bar 43P is arranged above the insulating layer 43I1, and the insulating layer 43I2 is arranged in the uppermost layer.

[0196] As described above, the W-phase positive-side DC bus bar 43P is formed in a manner integrally connected to the U-phase positive-side DC bus bar 41P and the V-phase positive-side DC bus bar 42P.

[0197] As described above, the W-phase negative-side DC bus bar 43N is formed in a manner integrally connected to the U-phase negative-side DC bus bar 41N and the V-phase negative-side DC bus bar 42N.

[0198] As described above, the insulating layer 43I1 can be formed in a manner integrally connected to the insulating layer 41I1 and the insulating layer 42I1. Similarly, as described above, the insulating layer 43I2 can be formed in a manner integrally connected to the insulating layer 41I2 and the insulating layer 42I2.

[0199] 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 is omitted.

[0200] As Figures 2 - 6 , 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.

[0201] Since the configuration and structure of the W-phase AC bus 43O are the same as those of the U-phase AC bus 41O, the description thereof is omitted.

[0202] The laminated bus bar 40PN can be arranged in the housing 1H in such a manner that the overlapping area between the positive-side DC bus bar 40P and the negative-side DC bus bar 40N is relatively large (preferably maximized). Additionally, the thicknesses of the insulating layers 41I1, 42I1, and 43I1 can be set in such a way that while ensuring the insulation of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N, the distance therebetween is relatively small. Thus, in terms of space, the current paths flowing in opposite directions can be made closer. 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 cancelled out. This is because, for example, when a U-phase current flows through the positive-side DC bus bar 40P, V-phase and W-phase currents flow through the negative-side DC bus bar 40N. Thereby, the inductances of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N can be reduced. Additionally, as described above, when the current densities are approximately equal, the magnitudes of the magnetic fields generated by the current in the positive-side DC bus bar 40P and the current in the negative-side DC bus bar 40N are approximately equal, so that the generated magnetic fields can be substantially cancelled out. Therefore, the inductances of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N can be further suppressed. Thereby, along with the reduction of the inductances of the positive-side DC bus bar 40P and the negative-side DC bus bar 40N, the surge voltage of the power conversion device 1 can be suppressed.

[0203] In this way, 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 with an insulating layer 20I1 therebetween. 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 with insulating layers 41I1, 42I1, and 43I1 therebetween. Thereby, the inductance of the DC part in one cycle of the power path between the smoothing circuit 20 and the output terminal 40T can be reduced to be very small. Thereby, the surge voltage accompanying the ON / OFF of the semiconductor switches 410s, 420s, and 430s of the power conversion device 1 can be suppressed.

[0204] In addition, in the first embodiment, the U-phase parallel connection busbar 41O1 is configured such that the lengths of the power paths from the AC output terminals 410O of the respective four switching modules 410 to the U-phase output terminal 41T until they merge are substantially equal. Specifically, the U-phase parallel connection busbar 41O1 is configured such that the lengths of the power paths between the connection portions of the four switching modules 410 (the AC output terminals 410O thereof) and the U-phase output busbar 41O2 are substantially equal. Thereby, the difference in the inductances of the respective power paths between the AC output terminals 410O of the four switching modules 410 and the U-phase output terminal 41T can be made relatively small. Thereby, the difference in the inductances of the respective power paths of one cycle of the four switching modules 410 between the smoothing circuit 20 and the U-phase output terminal 41T can be made relatively small. In addition, the U-phase parallel connection busbar 41O1 is configured such that the current density of each power path from the AC output terminals 410O of the respective four switching modules 410 to the U-phase output terminal 41T until they merge is substantially equal. Thereby, the inductances of all the respective power paths between the AC output terminals 410O of the four switching modules 410 and the U-phase output terminal 41T can be made substantially equal. Thereby, the inductances of the respective power paths of one cycle of the four switching 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 busbar 42O1 is configured such that the lengths of the power paths from the AC output terminals 420O of the respective four switching modules 420 to the V-phase output terminal 42T until they merge are substantially equal. Thereby, the difference in the inductances of the respective power paths between the AC output terminals 420O of the four switching modules 420 and the V-phase output terminal 42T can be made relatively small. Thereby, the difference in the inductances of the respective power paths of one cycle of the four switching modules 420 between the smoothing circuit 20 and the V-phase output terminal 42T can be made relatively small. In addition, the V-phase parallel connection busbar 42O1 is configured such that the current density of each power path from the AC output terminals 420O of the respective four switching modules 420 to the V-phase output terminal 42T until they merge is substantially equal. Thereby, the inductances of all the respective power paths between the AC output terminals 420O of the four switching modules 420 and the V-phase output terminal 42T can be made substantially equal. Thereby, the inductances of the respective power paths of one cycle of the four switching modules 420 between the smoothing circuit 20 and the V-phase output terminal 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 switching modules 430 to the W-phase output terminal 43T until they merge are substantially equal. Thereby, the difference in the inductances of the respective power paths between the AC output terminals 430O of the four switching modules 430 and the W-phase output terminal 43T can be made relatively small.Therefore, it is possible to make the difference in the inductance of each of the power paths of one cycle of the four switching modules 430 between the smoothing circuit 20 and the W-phase output terminal 43T relatively small. In addition, the W-phase parallel connection bus 43O1 is configured such that the current density of the power path from the AC output terminals 430O of the four switching modules 430 to the W-phase output terminal 43T until they merge is substantially equal. As a result, it is possible to make the inductances of all the power paths between the AC output terminals 430O of the four switching modules 430 and the W-phase output terminal 43T substantially equal. As a result, it is possible to make the inductances of the power paths of one cycle of the four switching modules 430 between the smoothing circuit 20 and the W-phase output terminal 43T substantially equal. As described above, this is because the inductance of the DC part in the power path of one cycle between the smoothing circuit 20 and the output terminal 40T is very small, and the inductance of the AC part is dominant. As a result, it is possible to suppress the imbalance of the currents of the four switching modules 410, the four switching modules 420, and the four switching modules 430, and thus it is possible to achieve current homogenization.

[0205] In addition, in the first embodiment, the number of the switch modules 410 connected in parallel can be any number as long as the lengths of all the power paths from the AC output terminals 410O of the respective switch modules 410 to the confluence point of the power paths leading to the U-phase output terminal 41T are substantially equal. That is, the number of the switch modules 410 connected in parallel can be two or three, or five or more. For example, when the number of the switch modules 410 connected in parallel is two, the U-phase parallel connection bus 41O1 can be constituted only by the leg 41O1a, and is connected to the U-phase output bus 41O2 at a substantially central position (midpoint) in the X-axis direction at the upper end of the leg 41O1a. In addition, the number of the switch modules 420 and the switch modules 430 can be the same. In addition, in the first embodiment, for the plurality of switch modules 410, they can be arbitrarily arranged as long as the lengths of all the paths from the AC output terminals 410O of the respective switch modules 410 to the confluence point of the power paths leading to the U-phase output terminal 41T are substantially equal. For example, three or more of the switch modules 410 can be arranged in the X-axis direction. In addition, for example, the plurality of switch modules 410 can be arranged in a row in the X-axis direction, or the columns in the X-axis direction can be arranged in three or more columns in the Y-axis direction. For example, it is preferable that the number of arrangements in the X-axis direction and the Y-axis direction is a power of two. Thus, as described above, it is possible to merge the paths from the respective AC output terminals 410O of the plurality of switch modules 410 in such a manner that the lengths of every two paths are equal, and at the same time, make the lengths of all the paths and the current density of each path substantially the same. In addition, the arrangements of the switch modules 420 and the switch modules 430 can be the same. In addition, in the first embodiment, for the constitution of the U-phase parallel connection bus 41O1, it can be any constitution as long as the lengths of all the paths from the AC output terminals 410O of the respective switch modules 410 to the confluence point of the power paths leading to the U-phase output terminal 41T are substantially equal. For example, for the U-phase parallel connection bus 41O1, as long as the lengths of all the paths from the AC output terminals 410O of the four switch modules 410 to the confluence point of the power paths leading to the U-phase output terminal 41T are substantially equal, it can be a constitution that is not symmetric as described above. Specifically, the two legs 41O1a of the U-phase parallel connection bus 41O1 can be constituted by substantially the same shape that is separated from each other in the Y-axis direction instead of a shape that is symmetric with respect to the vertical plane in the Y-axis direction. In addition, the constitutions of the V-phase parallel connection bus 42O1 and the W-phase parallel connection bus 43O1 can be the same.

[0206] [Second Embodiment]

[0207] Next, refer to Figures 7 - 10, the second embodiment will be described. Hereinafter, the description will focus on the parts different from the power conversion device 1 of the first embodiment, and the description of the same or corresponding parts as those of the first embodiment may be simplified or omitted sometimes.

[0208] <Overview of the Power Conversion Device>

[0209] Figure 7 It is a circuit diagram showing an example of the power conversion device 1 of the second embodiment.

[0210] As Figure 7 shown, the power conversion device 1 includes a rectifier circuit 10, a smoothing circuit 20, a fuse 30, and an inverter circuit 40 in the same manner as in the first embodiment.

[0211] 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 in the same manner as in the first embodiment.

[0212] The U-phase circuit 41 includes a U-phase positive-side DC bus 41P, a U-phase negative-side DC bus 41N, switching modules 411 to 414, and a U-phase AC bus 41O in the same manner as in the first embodiment. In addition, different from the case of the first embodiment, the U-phase circuit 41 further includes switching modules 415 and 416. Hereinafter, in the second embodiment and the third and fourth embodiments described later, the switching modules 411 to 416 may be collectively referred to as "switching module 410", or any one of the switching modules 411 to 416 may be individually referred to as "switching module 410". That is, different from the case of the first embodiment, the U-phase circuit 41 includes six switching modules 410.

[0213] The switching modules 411 to 416 (an example of a switching arm) are connected in parallel between the U-phase positive-side DC bus 41P and the U-phase negative-side DC bus 41N.

[0214] The switching 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.

[0215] The switching 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.

[0216] Hereinafter, in the second embodiment and 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 "semiconductor switch 410s". Further, in the second embodiment and the third and fourth embodiments described later, the components corresponding to the positive terminal 411P to 416P of the above-mentioned "switch module 410" may be referred to as "positive terminal 410P". Further, in the second embodiment and the third and fourth embodiments described later, the components corresponding to the negative terminal 411N to 416N of the above-mentioned "switch module 410" may be referred to as "negative terminal 410N". Further, in the second embodiment and 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".

[0217] The switch modules 411 to 416 have the same components and are composed of the same circuit.

[0218] One end of the U-phase AC bus 41O is connected to the AC output terminals 411O to 416O of the switch modules 411 to 416, and the other end is connected to the U-phase output terminal 41T. Thereby, the inverter circuit 40 can output the U-phase alternating current output from the switch modules 411 to 416 to the outside from the U-phase output terminal 41T.

[0219] The V-phase circuit 42 includes a V-phase positive-side DC bus 42P, a V-phase negative-side DC bus 42N, switch modules 421 to 424, and a V-phase AC bus 42O in the same manner as in the first embodiment. In addition, 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 "switch module 420", 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.

[0220] The switch modules 421 to 426 are connected in parallel between the V-phase positive-side DC bus 42P and the V-phase negative-side DC bus 42N.

[0221] The switching module 425 includes semiconductor switches 425s1 and 425s2 equivalent to upper and lower bridge arms, freewheeling diodes 425d1 and 425d2, a positive-side terminal 425P, a negative-side terminal 425N, and an AC output terminal 425O.

[0222] The switching module 426 includes semiconductor switches 426s1 and 426s2 equivalent to upper and lower bridge arms, freewheeling diodes 426d1 and 426d2, a positive-side terminal 426P, a negative-side terminal 426N, and an AC output terminal 426O.

[0223] Hereinafter, in the second embodiment and the third and fourth embodiments described later, the semiconductor switches 421s1, 421s2, 422s1, 422s2, 423s1, 423s2, 424s1, 424s2, 425s1, 425s2, 426s1, and 426s2 may be collectively referred to as "semiconductor switch 420s", or any one of them may be individually referred to as "semiconductor switch 420s". Further, in the second embodiment and the third and fourth embodiments described later, the elements corresponding to the positive-side terminals 421P to 426P of the above-mentioned "switching module 420" may be referred to as "positive-side terminal 420P". Further, in the second embodiment and the third and fourth embodiments described later, the elements corresponding to the negative-side terminals 421N to 426N of the above-mentioned "switching module 420" may be referred to as "negative-side terminal 420N". Further, in the second embodiment and the third and fourth embodiments described later, the elements corresponding to the AC output terminals 421O to 426O of the above-mentioned "switching module 420" may be referred to as "AC output terminal 420O".

[0224] The switching modules 421 to 426 have the same components and are composed of the same circuit.

[0225] One end of the V-phase AC bus 42O connects the respective AC output terminals 421O to 426O of the switching modules 421 to 426 to each other, and the other end thereof is connected to the V-phase output terminal 42T. Thus, the inverter circuit 40 can output the V-phase alternating current output from the switching modules 421 to 426 to the outside from the V-phase output terminal 42T.

[0226] The W-phase circuit 43 includes a W-phase positive-side DC bus 43P, a W-phase negative-side DC bus 43N, switching modules 431 to 434, and a W-phase AC bus 43O, which are the same as those in the first embodiment. Additionally, different from the first embodiment, the W-phase circuit 43 further includes switching modules 435 and 436. Hereinafter, in the second embodiment and the third and fourth embodiments described later, the switching modules 431 to 436 may be collectively referred to as "switching module 430", or any one of the switching modules 431 to 436 may be individually referred to as "switching module 430". That is, different from the case of the first embodiment, the W-phase circuit 43 includes six switching modules 430.

[0227] The switching modules 431 to 436 are connected in parallel between the W-phase positive-side DC bus 43P and the W-phase negative-side DC bus 43N.

[0228] The switching module 435 includes semiconductor switches 435s1 and 435s2 corresponding to the upper and lower bridge arms, freewheeling diodes 435d1 and 435d2, a positive-side terminal 435P, a negative-side terminal 435N, and an AC output terminal 435O.

[0229] The switching module 436 includes semiconductor switches 436s1 and 436s2 corresponding to the upper and lower bridge arms, freewheeling diodes 436d1 and 436d2, a positive-side terminal 436P, a negative-side terminal 436N, and an AC output terminal 436O.

[0230] Hereinafter, in the second embodiment and the third and fourth embodiments described later, the semiconductor switches 431s1, 431s2, 432s1, 432s2, 433s1, 433s2, 434s1, 434s2, 435s1, 435s2, 436s1, and 436s2 may be collectively referred to as "semiconductor switch 430s", or any one of them may be individually referred to as "semiconductor switch 430s". Additionally, in the second embodiment and the third and fourth embodiments described later, the components corresponding to the positive-side terminals 431P to 436P of the above-mentioned "switching module 430" may be referred to as "positive-side terminal 430P". Additionally, in the second embodiment and the third and fourth embodiments described later, the components corresponding to the negative-side terminals 431N to 436N of the above-mentioned "switching module 430" may be referred to as "negative-side terminal 430N". Additionally, in the second embodiment and the third and fourth embodiments described later, the components corresponding to the AC output terminals 431O to 436O of the above-mentioned "switching module 430" may be referred to as "AC output terminal 430O".

[0231] The switching modules 431 to 436 have the same components and are composed of the same circuit.

[0232] The W-phase AC busbar 43O connects the AC output terminals 431O to 436O of the respective switch modules 431 to 436 to each other at one end thereof, and is connected to the W-phase output terminal 43T at the other end thereof. Thus, the inverter circuit 40 can output the W-phase alternating current output from the switch modules 431 to 436 to the outside from the W-phase output terminal 43T.

[0233] <Structure of the power conversion device>

[0234] Figure 8 , Figure 9 is a structural diagram showing an example of the power conversion device of the second embodiment. Specifically, Figure 8 is a perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed. Figure 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 busbar 41O, V-phase AC busbar 42O, and W-phase AC busbar 43O are removed and moved upward. Figure 10 is a diagram for explaining the path of the current flowing through each of the switch modules 410 arranged in the X-axis direction. In Figure 10 , the paths of the currents passing through the three switch modules 410 arranged in the X-axis direction are sequentially represented by blank arrows, slant-shaded arrows, and blackened arrows from the switch module 410 closest to the smoothing circuit 20.

[0235] As Figure 8 , Figure 9 shown, the smoothing circuit 20, the fuse 30, and the inverter circuit 40 are arranged in sequence from one end portion to the other end portion (i.e., in the positive X-axis direction) in the longitudinal direction inside the housing 1H in the same manner as in the first embodiment.

[0236] In addition, 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 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.

[0237] As described above, the output terminal 40T includes 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 sequence from one end portion to the central portion (i.e., in the positive Y-axis direction) in the short-side direction inside the housing 1H in the same manner as in the first embodiment.

[0238] 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.

[0239] As Figure 8 , Figure 9 shown, the U-phase circuit 41, the V-phase circuit 42, and the W-phase circuit 43 are arranged in sequence in the Y-axis direction from the end portion on the negative Y-axis side toward the end portion on the positive Y-axis side, in the same manner as in the first embodiment.

[0240] The U-phase circuit 41 includes six switching modules 410 (i.e., corresponding to the above-described switching modules 411 to 416).

[0241] The six switching modules 410 are arranged in two groups with three arranged at equal intervals in the X-axis direction and arranged in two columns in the Y-axis direction. In addition, the six switching modules 410 are arranged on top of other components placed on the bottom surface of the housing 1H, in the same manner as in the first embodiment.

[0242] The switching modules 410 are arranged such that the length direction in a top view is along the approximate X-axis direction, in the same manner as in the first embodiment. In the switching module 410, along its length direction (i.e., the X-axis direction), the AC output terminal 410O, the negative electrode side terminal 410N, and the positive electrode side terminal 410P are arranged in sequence in the order of approaching the smoothing circuit 20 (smoothing capacitor 21).

[0243] As Figure 8 , Figure 9 shown, at the upper end portion of the switching module 410, the U-phase laminated bus bar 41PN is arranged in a manner substantially parallel to the X-axis direction and the Y-axis direction, in the same manner as in the first embodiment.

[0244] The U-phase laminated bus bar 41PN is arranged over a range covering the six switching modules 410 in the X-axis direction and the Y-axis direction.

[0245] As Figure 8 , Figure 9 shown, the U-phase AC bus bar 41O connects between the AC output terminal 410O of the switching 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, in the same manner as in the first embodiment.

[0246] As Figure 8 , Figure 9As shown, the U-phase parallel connection busbar 41O1 is connected to the U-phase output busbar 41O2 near the switch module 410 that is the farthest from the self-smoothing circuit 20 among the six switch modules 410 in a top view. Specifically, the U-phase parallel connection busbar 41O1 is connected to the U-phase output busbar 41O2 at a position away from the smoothing circuit 20 in the X-axis direction of the switch module 410 at the end farthest from the smoothing circuit 20 in the group of three switch modules 410 arranged in two columns in the Y-axis direction and arranged in the X-axis direction in a top view.

[0247] More specifically, the U-phase parallel connection busbar 41O1 includes six legs 41O1a and a connecting portion 41O1b.

[0248] Each of the six legs 41O1a has a flat plate shape that is substantially parallel to the X-axis and the Z-axis. Each of the six legs 41O1a has a supporting surface portion placed on the AC output terminals 410O of the six switch modules 410, and a main leg extending upward (in the positive Z-axis direction) from the supporting surface portion. In addition, the dimensions of each of the six legs 41O1a in the Z-axis direction are set to be substantially the same. In addition, the cross-sectional area of each of the six legs 41O1a is set to be substantially the same. Thereby, the current density of each of the six legs 41O1a can be made substantially equal.

[0249] The connecting portion 41O1b has a flat plate shape that is substantially parallel to the X-axis and the Y-axis, and connects the six legs 41O1a. Specifically, the connecting portion 41O1b has a substantially rectangular shape in a top view, and extends in the X-axis direction and the Y-axis direction so as to cover the range where the six legs 41O1a are arranged. The end portion of the connecting portion 41O1b in the positive X-axis direction is provided at a position away from 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 in the positive X-axis direction, and is connected to the U-phase output busbar 41O2.

[0250] As Figure 10As shown, the lengths of the paths in the Z-axis direction in the current path from the DC input terminal of the U-phase circuit 41 through the three switch modules 410 arranged in the X-axis direction until reaching the connection portion between the U-phase parallel connection bus 41O1 and the U-phase output bus 41O2 are all substantially equal. As described above, this is because the dimensions of the six legs 41O1a in the Z-axis direction are substantially the same. Additionally, the lengths of the paths in the X-axis direction in the current path from the DC input terminal of the U-phase circuit 41 through the three switch modules 410 arranged in the X-axis direction until reaching the connection portion between the U-phase parallel connection bus 41O1 and the U-phase output bus 41O2 are also all substantially equal. This is because the laminated bus 20PN, the U-phase laminated bus 41PN, and the connection portion 41O1b are arranged substantially parallel to the X-axis direction and the Y-axis direction. Thus, the overall lengths of the current paths from the DC input terminal of the U-phase circuit 41 through each of the three switch modules 410 arranged in the X-axis direction until reaching the connection portion between the U-phase parallel connection bus 41O1 and the U-phase output bus 41O2 are all substantially equal. Additionally, the same applies to the three switch modules 410 arranged in the X-axis direction in the other column. Thus, the overall lengths of the current paths from the smoothing circuit 20 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 through each of the six switch modules 410 until reaching the smoothing circuit 20 are also all substantially equal.

[0251] Furthermore, for each of the six power paths passing through each of the six switch modules 410, the connection portion 41O1b sets its cross-sectional area, i.e., its width and thickness, such that its current density is substantially equal to that of the U-phase positive-side DC bus 41P and the U-phase negative-side DC bus 41N. Thus, 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, it is possible to make the inductances of one cycle 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 all substantially equal and uniform.

[0252] As Figure 8 , Figure 9 shown, the U-phase output bus 41O2 connects between the U-phase parallel connection bus 41O1 and the U-phase output terminal 41T. The U-phase output bus 41O2 has a folded-back portion that extends upward from the X-axis positive-end portion of the connection portion 41O1b of the U-phase parallel connection bus 41O1, and a main portion that extends toward the U-phase output terminal 41T substantially parallel to the X-axis direction and the Y-axis direction from the upper end of the folded-back portion.

[0253] The V-phase circuit 42 includes six switching modules 420 (equivalent to the above-mentioned switching modules 421 to 426) in the same way as the U-phase circuit 41.

[0254] Since the configuration structure of the six switching modules 420 is the same as that of the six switching modules 410 of the U-phase circuit 41, the description thereof is omitted.

[0255] The switching modules 420 are arranged in a manner such that the length direction in a top view is along the approximate X-axis direction, similar to the switching modules 410. In the switching module 420, along its length direction (i.e., the X-axis direction), the AC output terminal 420O, the negative-side terminal 420N, and the positive-side terminal 420P are arranged in sequence in the order of approaching the smoothing circuit 20 (smoothing capacitor 21).

[0256] At the upper end portion of the switching module 420, the V-phase laminated busbar 42PN is arranged in a manner approximately parallel to the X-axis direction and the Y-axis direction.

[0257] The V-phase laminated busbar 42PN is arranged over a range covering the six switching modules 420 in the X-axis direction and the Y-axis direction.

[0258] As Figure 8 、 Figure 9 shown, the V-phase AC busbar 42O connects between the AC output terminal 420O of the switching module 420 and the V-phase output terminal 42T. The V-phase AC busbar 42O includes a V-phase parallel connection busbar 42O1 and a V-phase output busbar 42O2.

[0259] Since the configuration and structure of the V-phase AC busbar 42O are the same as those of the U-phase AC busbar 41O, the description thereof is omitted.

[0260] The W-phase circuit 43 includes six switching modules 430 (equivalent to the above-mentioned switching modules 431 to 436) in the same way as the U-phase circuit 41.

[0261] Since the configuration structure of the six switching modules 430 is the same as that of the six switching modules 410 of the U-phase circuit 41, the description thereof is omitted.

[0262] The switching modules 430 are arranged in a manner such that the length direction in a top view is along the approximate X-axis direction. In the switching module 430, along its length direction (i.e., the X-axis direction), the AC output terminal 430O, the negative-side terminal 430N, and the positive-side terminal 430P are arranged in sequence in the order of approaching the smoothing circuit 20 (smoothing capacitor 21).

[0263] At the upper end portion of the switching module 430, the W-phase laminated busbar 43PN is arranged in a manner approximately parallel to the X-axis direction and the Y-axis direction.

[0264] The W-phase laminated busbar 43PN is arranged to cover the range of six switching modules 430 in the X-axis direction and the Y-axis direction.

[0265] 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.

[0266] As Figure 8 、 Figure 9 shown, the W-phase AC busbar 43O connects between the AC output terminal 430O of the switching 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.

[0267] 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.

[0268] 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 ends of the U-phase laminated bus bars 41PN of the respective six switching modules 410 and the connection portions 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 ends of the U-phase laminated bus bars 41PN of the respective six switching modules 410 and the connection portions with the U-phase output bus bar 41O2 is substantially equal. Specifically, the six legs 41O1a are configured to have substantially the same length and substantially the same cross-sectional area, and the current density of each of them is substantially equal. Further, for each power path passing through the respective six switching modules 410, the connection portion 41O1b is configured such that its current density 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 to say, the U-phase parallel connection bus bar 41O1 is configured such that the lengths of each of the six power paths and the current density of the common portion (i.e., the six legs 41O1a) are substantially equal. And, the U-phase parallel connection bus bar 41O1 is configured such that the current density of the portion other than that, i.e., the portion corresponding to the difference in the lengths of each power path (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 the current densities of one cycle of the power paths between the smoothing circuit 20 and the U-phase output terminal 41T of the respective six switching modules 410 are substantially equal. Therefore, it is possible to make the inductances of one cycle of the power paths between the smoothing circuit 20 and the U-phase output terminal 41T of the respective six switching modules 410 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 ends of the V-phase laminated bus bars 42PN of the respective six switching modules 420 and the connection portions with the V-phase output bus bar 42O2 are all substantially equal. Further, 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 DC input ends of the V-phase laminated bus bars 42PN of the respective six switching modules 420 and the connection portions with the V-phase output bus bar 42O2 is substantially equal. Thereby, it is possible to make the inductances of one cycle of the power paths between the smoothing circuit 20 and the V-phase output terminal 42T of the respective six switching modules 420 substantially equal and uniform. Similarly, the W-phase parallel connection bus bar 43O1 is configured such that the lengths of the power paths between the DC input ends of the W-phase laminated bus bars 43PN of the respective six switching modules 430 and the connection portions with the W-phase output bus bar 43O2 are all substantially equal.In addition, the bus bar 43O1 for W-phase parallel connection is configured such that the current density is substantially equal over the entire path of each power path between the DC input terminal of the W-phase laminated bus bar 43PN passing through each of the six switching modules 430 and the connection portion with the W-phase output bus bar 43O2. Therefore, it is possible to make the inductances of one cycle of the power paths between the smoothing circuits 20 of each of the six switching modules 430 and the W-phase output terminals 43T substantially equal and uniform. As a result, it is possible to suppress the current imbalance in each of the six switching modules 410, the six switching modules 420, and the six switching modules 430, and thus it is possible to achieve current uniformity.

[0269] It should be noted that in the second embodiment, the number of the switching modules 410 connected in parallel may be any number as long as the lengths of the power paths between the DC input terminal of the U-phase laminated bus bar 41PN passing through each of the switching modules 410 and the connection portion with the U-phase output bus bar 41O2 are substantially equal and the current density over the entire path of each path is equal. That is, the number of the switching modules 410 connected in parallel may be two or more and five or less, or may be seven or more. In addition, the number of the switching modules 420 and the switching modules 430 may be the same. In addition, in the second embodiment, as long as the lengths of the power paths between the DC input terminal of the U-phase laminated bus bar 41PN passing through each of the switching modules 410 and the connection portion with the U-phase output bus bar 41O2 are substantially equal and the current density over the entire path of each path is equal, the plurality of switching modules 410 may be arranged arbitrarily. For example, the plurality of switching 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. In addition, the arrangements of the switching modules 420 and the switching modules 430 may be the same. In addition, in the second embodiment, as long as the lengths of the power paths between the DC input terminal of the U-phase laminated bus bar 41PN passing through each of the switching modules 410 and the connection portion with the U-phase output bus bar 41O2 are substantially equal and the current density over the entire path of each path is equal, the configuration of the U-phase parallel connection bus bar 41O1 may be arbitrary. For example, the U-phase parallel connection bus bar 41O1 may be configured such that the current density of each power path only in the portion between the connection portions of the connection portion 41O1b with the leg portions 41O1a at both ends in the X-axis direction is substantially equal to that of the U-phase positive-side DC bus bar 41P and the U-phase negative-side DC bus bar 41N. That is, the connection portion 41O1b of the U-phase parallel connection bus bar 41O1 is configured such that the current density in each path section from all the paths of each of the six switching modules 410 to the confluence is substantially equal to that of the U-phase positive-side DC bus bar 41P and the U-phase negative-side DC bus bar 41N. In addition, the configurations of the V-phase parallel connection bus bar 42O1 and the W-phase parallel connection bus bar 43O1 may be the same.

[0270] [Third Embodiment]

[0271] Next, with reference to Figure 11 and Figure 12 , the third embodiment will be described. Since the circuit configuration of the power conversion device 1 in the third embodiment is the same as that of the above-described second embodiment ( Figure 7 ), the description thereof will be omitted. Hereinafter, the description will focus on the parts different from the power conversion devices 1 of the first and second embodiments, and the description of the same or corresponding contents as those of the first and second embodiments may be simplified or omitted.

[0272] <Structure of Power Conversion Device>

[0273] Figure 11 and Figure 12 are structural diagrams showing an example of the power conversion device 1 of the third embodiment. Specifically, Figure 11 is a perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed. Figure 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, V-phase output bus bar 42O2, and W-phase output bus bar 43O2 are removed and moved upward.

[0274] As shown in Figure 11 and Figure 12 , similar to the case of the first embodiment and the like, the smoothing circuit 20, the fuse 30, and the inverter circuit 40 are arranged in sequence from one end to the other end in the longitudinal direction inside the housing 1H (i.e., in the positive X-axis direction).

[0275] In addition, similar to the case of the first embodiment and the like, the output terminal 40T is disposed 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 disposed above the smoothing circuit 20 and the fuse 30 inside the housing 1H.

[0276] As described above, the output terminal 40T includes a U-phase output terminal 41T, a V-phase output terminal 42T, and a W-phase output terminal 43T. Similar to the case of the first embodiment and the like, the U-phase output terminal 41T, the V-phase output terminal 42T, and the W-phase output terminal 43T are arranged in sequence from one end to the central portion in the short side direction inside the housing 1H (i.e., in the positive Y-axis direction).

[0277] 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.

[0278] As Figure 11 、 Figure 12 shown, similar to the case of the first embodiment etc., the U-phase circuit 41, the V-phase circuit 42, and the W-phase circuit 43 are arranged in sequence in the Y-axis direction from the end portion in the negative Y-axis direction toward the end portion in the positive Y-axis direction.

[0279] Similar to the case of the second embodiment, the U-phase circuit 41 includes six switching modules 410 (i.e., corresponding to the above-described switching modules 411 to 416).

[0280] Similar to the case of the second embodiment, the six switching modules 410 are arranged in two columns in the Y-axis direction with three of them arranged at equal intervals in the X-axis direction. Additionally, similar to the case of the first embodiment etc., the six switching modules 410 are arranged above other components placed on the bottom surface of the housing 1H.

[0281] Similar to the case of the first embodiment etc., the switching module 410 is arranged such that its length direction in plan view is along the approximate X-axis direction. In the switching module 410, along its length direction (i.e., the X-axis direction), the AC output terminal 410O, the negative-side terminal 410N, and the positive-side terminal 410P are arranged in sequence in the order approaching the smoothing circuit 20 (smoothing capacitor 21).

[0282] As Figure 12 shown, at the upper end portion of the switching module 410, similar to the case of the first embodiment etc., the U-phase laminated bus bar 41PN is arranged in a manner substantially parallel to the X-axis direction and the Y-axis direction.

[0283] The U-phase laminated bus bar 41PN is arranged so as to cover the range of the six switching modules 410 in the X-axis direction and the Y-axis direction.

[0284] As Figure 12 shown, the U-phase AC bus bar 41O connects between the AC output terminal 410O of the switching module 410 and the U-phase output terminal 41T. Similar to the case of the first embodiment etc., the U-phase AC bus bar 41O includes a U-phase parallel connection bus bar 41O1 and a U-phase output bus bar 41O2.

[0285] The U-phase parallel connection bus bar 41O1 has a flat plate shape substantially parallel to the X-axis direction and the Y-axis direction, and has a substantially rectangular shape that covers the range of the six switching modules 410 in plan view. The U-phase parallel connection bus bar 41O1 is on the uppermost insulating layer 41I2 of the U-phase laminated bus bar 41PN (refer to Figure 4) is further stacked on top. Thus, the U-phase negative-side DC bus 41N, the U-phase positive-side DC bus 41P, and the U-phase parallel connection bus 41O1 constitute a U-phase laminated bus 41PNO of a laminated structure stacked sequentially from bottom to bottom via insulating layers 41I1 and 41I2. Therefore, the current density of the U-phase parallel connection bus 41O1 is substantially equal to that of the U-phase positive-side DC bus 41P and the U-phase negative-side DC bus 41N.

[0286] like Figure 11 , Figure 12 As shown, in the U-phase parallel connection bus 41O1, relatively large through holes that are roughly rectangular when viewed from above are provided at positions corresponding to the six switch modules 410. As a result, the positive terminal 410P (i.e., the through hole for fastening the U-phase positive side DC bus 41P), the negative terminal 410N (i.e., the through hole for fastening the U-phase negative side DC bus 41N), and the AC output terminal 410O of the switch module 410 can be exposed when viewed from above. Therefore, the staff can touch the positive terminal 410P, the negative terminal 410N, and the AC output terminal 410O of the switch module 410 from above the U-phase parallel connection bus 41O1.

[0287] like Figure 11 , Figure 12 As shown, the U-phase output bus 41O2 connects the U-phase parallel connection bus 41O1 and the U-phase output terminal 41T. The U-phase output bus 41O2 is connected at the end of the U-phase parallel connection bus 41O1 in the positive direction of the X axis, that is, at a position farther away from the AC output terminal 410O of the switch module 410 in the positive direction of the X axis than the end of the switch modules 410 arranged in two rows in the positive direction of the X axis. In addition, the U-phase output bus 41O2 is connected at the end of the U-phase parallel connection bus 41O1 in the positive direction of the X axis and at a substantially central position in the Y axis direction between the AC output terminals 410O of the group of switch modules 410 arranged in two rows in the X axis direction. As a result, the lengths of the power paths between the DC input end of the U-phase circuit 41 and the connection portion between the U-phase parallel connection bus 41O1 and the U-phase output bus 41O2 through each of the six switch modules 410 are all substantially equal. Therefore, the length and current density of the power path of one cycle 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. As a result, the inductance of the power path of one cycle between the smoothing circuit 20 and the U-phase output terminal 41T passing through the six switch modules 410 can be substantially equalized and uniformed.

[0288] Similar to the U-phase circuit 41 , the V-phase circuit 42 includes six switch modules 420 (equivalent to the switch modules 421 to 426 ).

[0289] Since the configuration structure of the six switching modules 420 is the same as that of the six switching modules 410 of the U-phase circuit 41, the description thereof is omitted.

[0290] Similar to the switching module 410, the switching module 420 is arranged in a manner such that its length direction in a top view is along the approximate X-axis direction. In the switching module 420, the AC output terminal 420O, the negative-side terminal 420N, and the positive-side terminal 420P are arranged in sequence along its length direction (i.e., the X-axis direction) in an order approaching the smoothing circuit 20 (smoothing capacitor 21).

[0291] As Figure 12 shown, at the upper end portion of the switching module 420, the V-phase laminated bus 42PN is arranged in a manner approximately parallel to the X-axis direction and the Y-axis direction.

[0292] The V-phase laminated bus 42PN is arranged in a manner covering the range of the six switching modules 420 in the X-axis direction and the Y-axis direction.

[0293] As Figure 12 shown, the V-phase AC bus 42O connects between the AC output terminal 420O of the switching module 420 and the V-phase output terminal 42T. The V-phase AC bus 42O includes a V-phase parallel connection bus 42O1 and a V-phase output bus 42O2.

[0294] The V-phase parallel connection bus 42O1 has a flat plate shape approximately parallel to the X-axis direction and the Y-axis direction, and has an approximately rectangular shape covering the range of the six switching modules 420 in a top view. The V-phase parallel connection bus 42O1 is further laminated on the uppermost insulating layer 42I2 (refer to Figure 4 ) of the V-phase laminated bus 42PN. Thus, the V-phase negative-side DC bus 42N, the V-phase positive-side DC bus 42P, and the V-phase parallel connection bus 42O1 form a laminated structure of the V-phase laminated bus 42PNO laminated in sequence from bottom to top with the insulating layers 42I1 and 42I2 therebetween. Therefore, the current density of the V-phase parallel connection bus 42O1 is approximately equal to that of the V-phase positive-side DC bus 42P and the V-phase negative-side DC bus 42N.

[0295] Since the arrangement and structure of the V-phase AC bus 42O (the V-phase parallel connection bus 42O1 and the V-phase output bus 42O2) are the same as those of the U-phase AC bus 41O, the description thereof is omitted.

[0296] Similar to the U-phase circuit 41, the W-phase circuit 43 includes six switching modules 430 (corresponding to the above-mentioned switching modules 431 to 436).

[0297] Since the configuration 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.

[0298] Similar to the switch module 410, the switch module 430 is arranged in a manner such that its length direction in a top view is along the approximate X-axis direction. In the switch module 430, along its length direction (i.e., the X-axis direction), the AC output terminal 430O, the negative-side terminal 430N, and the positive-side terminal 430P are arranged in sequence in the order approaching the smoothing circuit 20 (smoothing capacitor 21).

[0299] As Figure 12 shown, at the upper end portion of the switch module 430, the W-phase laminated bus bar 43PN is arranged in a manner approximately parallel to the X-axis direction and the Y-axis direction.

[0300] The W-phase laminated bus bar 43PN is arranged in a manner covering the range of the six switch modules 430 in the X-axis direction and the Y-axis direction.

[0301] As Figure 12 shown, 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.

[0302] The W-phase parallel connection bus bar 43O1 has a flat plate shape approximately parallel to the X-axis direction and the Y-axis direction, and has an approximately rectangular shape covering the range of the six switch modules 430 in a top view. The W-phase parallel connection bus bar 43O1 is further laminated on top of the topmost insulating layer 43I2 of the W-phase laminated bus bar 43PN (refer to Figure 4 ). Thus, 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 form a laminated structure of the W-phase laminated bus bar 43PNO laminated in sequence from bottom to top with the insulating layers 43I1 and 43I2 in between. Therefore, the current density of the W-phase parallel connection bus bar 43O1 is approximately equal to that of the W-phase positive-side DC bus bar 43P and the W-phase negative-side DC bus bar 43N.

[0303] Since the arrangement and structure of the W-phase AC bus bar 43O (the W-phase parallel connection bus bar 43O1 and the W-phase output bus bar 43O2) are the same as those of the U-phase AC bus bar 41O, the description thereof is omitted.

[0304] Thus, in the third embodiment, there is a laminated structure in which the U-phase parallel connection busbar 41O1, the U-phase positive-side DC busbar 41P, and the U-phase negative-side DC busbar 41N are laminated with each other with insulating layers 41I1 and 41I2 therebetween. Further, the U-phase parallel connection busbar 41O1 is connected to the U-phase output busbar 41O2 at a position farther from 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 in the positive X-axis direction. Thereby, the lengths and current densities of one cycle of the power paths between the smoothing circuit 20 and the U-phase output terminal 41T through each of the six switch modules 410 are all substantially equal. Therefore, it is possible to make the inductances of one cycle of the power paths between the smoothing circuit 20 and the U-phase output terminal 41T through each of the six switch modules 410 substantially equal and uniform. Similarly, there is a laminated structure in which the V-phase parallel connection busbar 42O1, the V-phase positive-side DC busbar 42P, and the V-phase negative-side DC busbar 42N are laminated with each other with insulating layers 42I1 and 42I2 therebetween. Further, the V-phase parallel connection busbar 42O1 is connected to the V-phase output busbar 42O2 at a position farther from 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 in the positive X-axis direction. Thereby, the lengths and current densities of one cycle of the power paths between the smoothing circuit 20 and the V-phase output terminal 42T through each of the six switch modules 420 are all substantially equal. Therefore, it is possible to make the inductances of one cycle of the power paths between the smoothing circuit 20 and the V-phase output terminal 42T through each of the six switch modules 420 substantially equal and uniform. Similarly, there is a laminated structure in which the W-phase parallel connection busbar 43O1, the W-phase positive-side DC busbar 43P, and the W-phase negative-side DC busbar 43N are laminated with each other with insulating layers 43I1 and 43I2 therebetween. Further, the W-phase parallel connection busbar 43O1 is connected to the W-phase output busbar 43O2 at a position farther from 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 in the positive X-axis direction. Thereby, the lengths and current densities of one cycle of the power paths between the smoothing circuit 20 and the W-phase output terminal 43T through each of the six switch modules 430 are all substantially equal. Therefore, it is possible to make the inductances of one cycle of the power paths between the smoothing circuit 20 and the W-phase output terminal 43T through each of the six switch modules 430 substantially equal and uniform. Thereby, it is possible to suppress the current imbalance in each of the six switch modules 410, the six switch modules 420, and the six switch modules 430, and thus it is possible to achieve current uniformity.

[0305] In addition, in the third embodiment, the number of switch modules 410 connected in parallel can be any number, which can be two or more and five or less, or can be seven or more. The same applies to the number of switch modules 420 and switch modules 430. In addition, in the third embodiment, the arrangement of the plurality of switch modules 410 can be arbitrary. For example, the plurality of switch modules 410 can be arranged in a row in the X-axis direction, or a group of rows arranged in the X-axis direction can be arranged in three or more rows in the Y-axis direction.

[0306] [Fourth Embodiment]

[0307] Next, with reference to Figure 13 、 Figure 14 , the fourth embodiment will be described. Since the circuit configuration of the power conversion device 1 in the fourth embodiment is the same as that of the above-described second embodiment ( Figure 7 ), the description thereof will be omitted. Hereinafter, the description will be centered on the parts different from the power conversion device 1 of the first to third embodiments, and the description of the same or corresponding contents as those of the first to third embodiments may be simplified or omitted.

[0308] <Structure of Power Conversion Device>

[0309] Figure 13 、 Figure 14 are structural diagrams showing an example of the power conversion device 1 of the fourth embodiment. Specifically, Figure 13 is a perspective view showing a state in which a part of the housing 1H of the power conversion device 1 is removed. Figure 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, the output terminal 40T is removed and moved upward.

[0310] As Figure 13 、 Figure 14 shown, similar to the case of the first embodiment and the like, the smoothing circuit 20, the fuse 30, and the inverter circuit 40 are arranged in sequence from one end to the other end in the length direction inside the housing 1H (i.e., in the positive X-axis direction).

[0311] In addition, similar to the case of the first embodiment and the like, the output terminal 40T is arranged at the central portion in the length 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.

[0312] As described above, the output terminal 40T includes a U-phase output terminal 41T, a V-phase output terminal 42T, and a W-phase output terminal 43T. Similar to the case of the first embodiment and the like, the U-phase output terminal 41T, the V-phase output terminal 42T, and the W-phase output terminal 43T are arranged in sequence from one end portion in the short side direction inside the housing 1H to the central portion (i.e., in the positive Y-axis direction).

[0313] 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.

[0314] As Figure 13 , Figure 14 shown, similar to the case of the first embodiment and the like, the U-phase circuit 41, the V-phase circuit 42, and the W-phase circuit 43 are arranged in sequence in the Y-axis direction from the end portion in the negative Y-axis direction toward the end portion in the positive Y-axis direction.

[0315] Similar to the case of the second embodiment and the like, the U-phase circuit 41 includes six switching modules 410 (i.e., corresponding to the above-described switching modules 411 to 416).

[0316] Similar to the case of the second embodiment and the like, the six switching modules 410 are arranged in two rows in the Y-axis direction with three arranged at equal intervals in the X-axis direction. In addition, similar to the case of the first embodiment and the like, the six switching modules 410 are arranged on top of other components placed on the bottom surface of the housing 1H.

[0317] Similar to the case of the first embodiment and the like, the switching module 410 is arranged such that the length direction in a top view is along the approximate X-axis direction. In the switching module 410, along its length direction (i.e., the X-axis direction), the AC output terminal 410O, the negative-side terminal 410N, and the positive-side terminal 410P are arranged in sequence in the order of approaching the smoothing circuit 20 (smoothing capacitor 21).

[0318] As Figure 13 , Figure 14 shown, at the upper end portion of the switching module 410, similar to the case of the first embodiment and the like, the U-phase laminated bus bar 41PN is arranged in a manner substantially parallel to the X-axis direction and the Y-axis direction.

[0319] The U-phase laminated bus bar 41PN is arranged so as to cover the range of the six switching modules 410 in the X-axis direction and the Y-axis direction.

[0320] As Figure 13 , Figure 14As shown, 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. 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.

[0321] Similar to the third embodiment, 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 covers a range of six switch modules 410 in a top view. The U-phase parallel connection busbar 41O1 is further laminated on top of the insulating layer 41I2 (refer to Figure 4 ) of the uppermost layer of the U-phase laminated busbar 41PN. Thus, the U-phase negative-side DC busbar 41N, the U-phase positive-side DC busbar 41P, and the U-phase parallel connection busbar 41O1 form a laminated structure U-phase laminated busbar 41PNO that is laminated in order from bottom to top with the insulating layers 41I1 and 41I2 in between. Therefore, the current density of the U-phase parallel connection busbar 41O1 is substantially equal to that of the U-phase positive-side DC busbar 41P and the U-phase negative-side DC busbar 41N.

[0322] As Figure 13 , Figure 14As shown, the U-phase output bus 41O2 connects between the U-phase parallel connection bus 41O1 and the U-phase output terminal 41T. The U-phase output bus 41O2 is connected to the negative X-axis end of the U-phase parallel connection bus 41O1, that is, at a position farther from the AC output terminal 410 of the switch module 410 at the negative X-axis end of the three switch modules 410 arranged in two columns in the X-axis direction. In addition, the U-phase output bus 41O2 is connected to the negative X-axis end of the U-phase parallel connection bus 41O1 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 columns in the X-axis direction. Thus, the direction of the current flowing through the U-phase positive-side DC bus 41P toward each of the six switch modules 410 is the positive X-axis direction. On the other hand, the direction of the current flowing through the U-phase parallel connection bus 41O1 from each of the six switch modules 410 toward the U-phase output terminal 41T is the opposite negative X-axis direction. Therefore, currents with the same current density flow in opposite directions, and the magnetic fields generated by the currents in the U-phase positive-side DC bus 41P and the U-phase parallel connection bus 41O1 respectively cancel each other out, so that its inductance can be greatly reduced. Similarly, the direction of the current flowing through the U-phase parallel connection bus 41O1 from the U-phase output terminal 41T toward each of the six switch modules 410 is the positive X-axis direction. On the other hand, the direction of the current flowing through the U-phase negative-side DC bus 41N from each of the six switch modules 410 toward the smoothing circuit 20 is the negative X-axis direction. Therefore, currents of the same magnitude flow in opposite directions, and the magnetic fields generated by the currents in the U-phase negative-side DC bus 41N and the U-phase parallel connection bus 41O1 respectively cancel each other out, so that its inductance can be greatly reduced. Thus, the inductance of each power path in one cycle between the smoothing circuit 20 and the U-phase output terminal 41T through the six switch modules 410 becomes very small, so that the difference in inductance between the power paths can be suppressed and the inductance can be made uniform.

[0323] Similar to the U-phase circuit 41, the V-phase circuit 42 includes six switch modules 420 (corresponding to the above-mentioned switch modules 421 to 426).

[0324] Since the configuration structure of the six switch modules 420 is the same as that of the six switch modules 410 in the U-phase circuit 41, the description is omitted.

[0325] Similar to the switch module 410, the switch module 420 is arranged with its length direction in a plan view along the substantially X-axis direction. In the switch module 420, along its length direction (i.e., the X-axis direction), the AC output terminal 420O, the negative-side terminal 420N, and the positive-side terminal 420P are arranged in sequence in the order of approaching the smoothing circuit 20 (smoothing capacitor 21).

[0326] As Figure 13, Figure 14 As shown in Figure 14 , at the upper end of the switch module 420, the V-phase laminated busbar 42PN is arranged in a manner substantially parallel to the X-axis direction and the Y-axis direction.

[0327] The V-phase laminated busbar 42PN is arranged in a manner that covers a range of six switch modules 420 in the X-axis direction and the Y-axis direction.

[0328] As Figure 13 , Figure 14 shown in Figure 14 , the V-phase AC busbar 42O connects between the AC output terminal 420O of the switch module 420 and the V-phase output terminal 42T. The V-phase AC busbar 42O includes a V-phase parallel connection busbar 42O1 and a V-phase output busbar 42O2.

[0329] Similar to the case of the third embodiment, the V-phase parallel connection busbar 42O1 has a flat plate shape substantially parallel to the X-axis direction and the Y-axis direction, and has a substantially rectangular shape that covers a range of six switch modules 420 in a top view. The V-phase parallel connection busbar 42O1 is further laminated on top of the uppermost insulating layer 42I2 of the V-phase laminated busbar 42PN (refer to Figure 4 ). Thus, the V-phase negative-side DC busbar 42N, the V-phase positive-side DC busbar 42P, and the V-phase parallel connection busbar 42O1 form a laminated structure of the V-phase laminated busbar 42PNO that is laminated in order from bottom to top with insulating layers 42I1 and 42I2 in between. Therefore, the current density of the V-phase parallel connection busbar 42O1 is substantially equal to that of the V-phase positive-side DC busbar 42P and the V-phase negative-side DC busbar 42N. Figure 4 )

[0330] Since the arrangement and structure of the V-phase AC busbar 42O (the V-phase parallel connection busbar 42O1 and the V-phase output busbar 42O2) are the same as those of the U-phase AC busbar 41O, the description thereof is omitted.

[0331] Similar to the U-phase circuit 41, the W-phase circuit 43 includes six switch modules 430 (corresponding to the above-mentioned switch modules 431 to 436).

[0332] 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.

[0333] Similar to the switch module 410, the switch module 430 is arranged in a manner that the length direction in a top view is along the substantially X-axis direction. In the switch module 430, the AC output terminal 430O, the negative-side terminal 430N, and the positive-side terminal 430P are arranged in order along its length direction (i.e., the X-axis direction) in a sequence approaching the smoothing circuit 20 (smoothing capacitor 21).

[0334] As Figure 13, Figure 14 As shown in Figure 14 , at the upper end of the switch module 430, the W-phase laminated busbar 43PN is arranged in a manner substantially parallel to the X-axis direction and the Y-axis direction.

[0335] The W-phase laminated busbar 43PN is arranged in a manner that covers a range of six switch modules 430 in the X-axis direction and the Y-axis direction.

[0336] As Figure 13 , Figure 14 shown in Figure 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.

[0337] 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 that covers a range of six switch modules 430 in a top view. The W-phase parallel connection busbar 43O1 is further laminated on top of the uppermost insulating layer 43I2 of the W-phase laminated busbar 43PN (refer to Figure 4 ). Thus, the W-phase negative-side DC busbar 43N, the W-phase positive-side DC busbar 43P, and the W-phase parallel connection busbar 43O1 form a laminated structure of the W-phase laminated busbar 43PNO that is laminated in order from bottom to top with insulating layers 43I1 and 43I2 in between. Therefore, the current density of the W-phase parallel connection busbar 43O1 is substantially equal to that of the W-phase positive-side DC busbar 43P and the W-phase negative-side DC busbar 43N.

[0338] 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 thereof is omitted.

[0339] Thus, in the fourth embodiment, there is a laminated structure in which the U-phase parallel connection bus 41O1, the U-phase positive-side DC bus 41P, and the U-phase negative-side DC bus 41N are laminated with each other with insulating layers 41I1 and 41I2 therebetween. Further, the U-phase parallel connection bus 41O1 is connected to the U-phase output bus 41O2 at a position farther from the AC output terminal 410O of the switch module 410 at the negative X-axis end among the six switch modules 410 in the negative X-axis direction. As a result, the currents of the U-phase positive-side DC bus 41P and the U-phase parallel connection bus 41O1 before and after each of the six switch modules 410 and the currents of the U-phase parallel connection bus 41O1 and the U-phase negative-side DC bus 41N become the same current density and are spatially opposite in direction. Therefore, the magnetic fields generated by the currents of the U-phase positive-side DC bus 41P and the U-phase parallel connection bus 41O1 and the currents of the U-phase parallel connection bus 41O1 and the U-phase negative-side DC bus 41N cancel each other out, so that the inductance of these power paths can be made very small. As a result, the difference in inductance between the paths of the power paths of one cycle between the smoothing circuit 20 and the U-phase output terminal 41T through each of the six switch modules 410 can be suppressed, and thus the homogenization of the inductance can be achieved. Similarly, there is a laminated structure in which the V-phase parallel connection bus 42O1, the V-phase positive-side DC bus 42P, and the V-phase negative-side DC bus 42N are laminated with each other with insulating layers 42I1 and 42I2 therebetween. Further, the V-phase parallel connection bus 42O1 is connected to the V-phase output bus 42O2 at a position farther from the AC output terminal 420O of the switch module 420 at the negative X-axis end among the six switch modules 420 in the negative X-axis direction. As a result, the currents of the V-phase positive-side DC bus 42P and the V-phase parallel connection bus 42O1 before and after each of the six switch modules 420 and the currents of the V-phase parallel connection bus 42O1 and the V-phase negative-side DC bus 42N become the same current density and are spatially opposite in direction. Therefore, the magnetic fields generated by the currents of the V-phase positive-side DC bus 42P and the V-phase parallel connection bus 42O1 and the currents of the V-phase parallel connection bus 42O1 and the V-phase negative-side DC bus 42N cancel each other out, so that the inductance of these power paths can be made very small. As a result, the difference in inductance between the paths of the power paths of one cycle between the smoothing circuit 20 and the V-phase output terminal 42T through each of the six switch modules 420 can be suppressed, and thus the homogenization of the inductance can be achieved. Similarly, there is a laminated structure in which the W-phase parallel connection bus 43O1, the W-phase positive-side DC bus 43P, and the W-phase negative-side DC bus 43N are laminated with each other with insulating layers 43I1 and 43I2 therebetween. Further, the W-phase parallel connection bus 43O1 is connected to the W-phase output bus 43O2 at a position farther from the AC output terminal 430O of the switch module 430 at the negative X-axis end among the six switch modules 430 in the negative X-axis direction.Accordingly, the currents of the W-phase positive-side DC bus 43P before and after each of the six switch modules 430, the current of the W-phase parallel connection bus 43O1, and the current of the W-phase parallel connection bus 43O1 and the W-phase negative-side DC bus 43N have the same current density and spatially opposite directions. Therefore, the magnetic fields generated by the current of the W-phase positive-side DC bus 43P and the W-phase parallel connection bus 43O1 and the current of the W-phase parallel connection bus 43O1 and the W-phase negative-side DC bus 43N cancel each other out, so that the inductance of these power paths can be made very small. As a result, the difference between the paths of the inductance of the power paths that circulate between the smoothing circuit 20 and the W-phase output terminal 43T through each of the six switch modules 430 can be suppressed, and thus the homogenization of the inductance can be achieved. Thereby, the imbalance of the currents of each of the six switch modules 410, the six switch modules 420, and the six switch modules 430 can be suppressed, and thus the homogenization of the current can be achieved.

[0340] In addition, in the fourth embodiment, the number of the parallel-connected switch modules 410 is an arbitrary number, which can be two or more and five or less, or can be seven or more. In addition, the number of the switch modules 420 and the switch modules 430 is the same. In addition, in the fourth embodiment, the arrangement of the multiple switch modules 410 is arbitrary. For example, the multiple switch modules 410 can be arranged in a row in the X-axis direction, or a group arranged in a row in the X-axis direction can be arranged in three or more rows in the Y-axis direction.

[0341] [Function]

[0342] Next, the function of the power conversion device 1 of the present embodiment will be described.

[0343] In the present embodiment (first embodiment), the power conversion device 1 includes a smoothing circuit 20, an inverter circuit 40, and output terminals 40T. Specifically, the inverter circuit 40 includes a U-phase circuit 41, which is configured by connecting in parallel a plurality of switching modules 410 each including upper and lower arms in which a plurality of semiconductor switches 410s are connected in series, and connecting the connection points (AC output terminals 410O) of the upper and lower arms of each of the plurality of switching modules 410 to each other. Similarly, the inverter circuit 40 includes a V-phase circuit 42, which is configured by connecting in parallel a plurality of switching modules 420 each including upper and lower arms in which a plurality of semiconductor switches 420s are connected in series, and connecting the connection points (AC output terminals 420O) of the upper and lower arms of each of the plurality of switching modules 420 to each other. Similarly, the inverter circuit 40 includes a W-phase circuit 43, which is configured by connecting in parallel a plurality of switching modules 430 each including upper and lower arms in which a plurality of semiconductor switches 430s are connected in series, and connecting the connection points (AC output terminals 430O) of the upper and lower arms of each of the plurality of switching modules 430 to each other. That is, the inverter circuit 40 includes a bridge circuit configured by connecting in parallel a plurality of phases through output circuits (U-phase circuit 41, V-phase circuit 42, and W-phase circuit 43). And, the inverter circuit 40 outputs a prescribed alternating current based on the direct current input from the smoothing circuit 20. In addition, the output terminals 40T output the prescribed alternating current from the inverter circuit 40 to the outside. In addition, the inverter circuit 40 includes a positive-side DC bus 40P that connects the positive-side terminals 410P, 420P, 430P of the plurality of switching modules 410, 420, 430 to each other, and a negative-side DC bus 40N that connects the negative-side terminals 410N, 420N, 430N of the plurality of switching modules 410, 420, 430 to each other. In addition, the inverter circuit 40 includes a U-phase parallel connection bus 41O1 that connects the AC output terminals 410O of the plurality of switching modules 410 to each other. Similarly, the inverter circuit 40 includes a V-phase parallel connection bus 42O1 that connects the AC output terminals 420O of the plurality of switching modules 420 to each other. Similarly, the inverter circuit 40 includes a W-phase parallel connection bus 43O1 that connects the AC output terminals 430O of the plurality of switching modules 430 to each other. In addition, the positive-side DC bus 40P and the negative-side DC bus 40N have a laminated structure in which insulating layers 41I1, 42I1, 43I1 are interposed therebetween. And, the U-phase parallel connection bus 41O1 is configured such that the lengths of the respective paths between all the arms (semiconductor switches 410s) included in the plurality of switching modules 410 and the confluence portion where all the paths from the plurality of switching modules 410 converge are substantially equal.Similarly, the bus bar 42O1 for V-phase parallel connection is configured such that the lengths of the respective paths between all the bridge arms (semiconductor switches 420s) included in the plurality of switching modules 420 and the confluence part where all the paths from the respective plurality of switching modules 420 merge are substantially equal. Similarly, the bus bar 43O1 for W-phase parallel connection is configured such that the lengths of the respective paths between all the bridge arms (semiconductor switches 430s) included in the plurality of switching modules 430 and the confluence part where all the paths from the respective plurality of switching modules 430 merge are substantially equal.

[0344] For example, in an inverter circuit, by connecting a plurality of switching bridge arms in parallel, the current capacity of a power conversion device can be increased.

[0345] In this case, if the inductance is different in each of the paths of the plurality of switching bridge arms, an imbalance occurs in the current flowing through the plurality of switching bridge arms, and the current may concentrate in the semiconductor switches included in a part of the switching bridge arms. As a result, the elements of the semiconductor switches may be damaged due to the temperature rise caused by the loss.

[0346] On the other hand, it is also possible to determine the current capacity of the power conversion device in consideration of the current imbalance by making the semiconductor switch with the most concentrated current comply with the allowable current. However, in this case, only a current relatively smaller than the allowable current can flow through the semiconductor switches other than the semiconductor switch with the concentrated current. As a result, even if the number of parallel-connected switching bridge arms is increased, the allowable current of the entire plurality of switching bridge arms cannot be effectively used, and thus the current capacity of the power conversion device may not be increased much.

[0347] In contrast, in the present embodiment (first embodiment), with the lamination structuring of the positive-side DC bus 40P and the negative-side DC bus 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, for the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T, the inductance of the AC wiring portion becomes dominant. Moreover, by configuring such that the respective path lengths from all the bridge arms (semiconductor switches 410s) included in the plurality of switching modules 410 to the confluence portion are 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 41O1 can be made relatively small. Therefore, in the power conversion device 1, for the power paths passing through the respective plurality of switching modules 410, the difference in the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T) can be made relatively small. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 410s (switching modules 410), and thus can achieve current homogenization. Additionally, the same applies to the plurality of switching modules 420. Therefore, in the power conversion device 1, for the power paths passing through the respective plurality of switching modules 420, the difference in the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T (V-phase output terminal 42T) can be made relatively small. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 420s (switching modules 420), and thus can achieve current homogenization. Additionally, the same applies to the plurality of switching modules 430. Therefore, in the power conversion device 1, for the power paths passing through the respective plurality of switching modules 430, the difference in the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T (W-phase output terminal 43T) can be made relatively small. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 430s (switching modules 430), and thus can achieve current homogenization.

[0348] Further, in the present embodiment (first embodiment), the U-phase parallel connection bus 41O1 is configured such that the current density of each path between all the semiconductor switches 410s included in the plurality of switching modules 410 and the confluence portion where all the paths from the respective plurality of switching modules 410 converge is substantially equal. Additionally, the same applies to the V-phase parallel connection bus 42O1 and the W-phase parallel connection bus 43O1.

[0349] Accordingly, it is possible to make the inductances of the power paths through the respective semiconductor switches 410s in the U-phase parallel connection bus bar 41O1 substantially equal. Therefore, in the power conversion device 1, for the power paths through the respective switch modules 410, it is possible to make the inductances of the power paths of one cycle between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T) substantially equal. Thereby, the power conversion device 1 can further suppress the current imbalance among the plurality of semiconductor switches 410s (switch modules 410), and thus can further achieve current homogenization. In addition, the same effect is achieved for the V-phase parallel connection bus bar 42O1 and the W-phase parallel connection bus bar 43O1.

[0350] In addition, in the present embodiment (first embodiment), two switch modules 410 included in the plurality of switch modules 410 are arranged and disposed in one axial direction (X-axis direction). The same applies to the plurality of switch modules 420 and the plurality of switch modules 430. In the U-phase parallel connection bus bar 41O1, the paths leading from the two switch modules 410 to the U-phase output terminal 41T merge 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 applies to the V-phase parallel connection bus bar 42O1 and the W-phase parallel connection bus bar 43O1.

[0351] Accordingly, in the U-phase parallel connection bus bar 41O1, for each combination of two switch modules 410, it is possible to make the paths leading from the respective AC output terminals 410O of the two switch modules 410 merge in such a manner that their lengths are substantially the same. The same effect is achieved for the V-phase parallel connection bus bar 42O1 and the W-phase parallel connection bus bar 43O1.

[0352] In addition, in the present embodiment (first embodiment), the plurality of parallel-connected switch modules 410 may include a plurality of combinations of two switch modules 410. The same applies to the plurality of parallel-connected switch modules 420 and the plurality of parallel-connected switch modules 430. The U-phase parallel connection bus bar 41O1 may be configured such that the lengths of the respective power paths between the intermediate merging portions where the paths of each combination of two switch modules 410 merge and the merging portion where the paths of all the switch modules 410 merge are substantially equal. The same applies to the V-phase parallel connection bus bar 42O1 and the W-phase parallel connection bus bar 43O1.

[0353] Accordingly, for the U-phase parallel connection bus bar 41O1, it is possible to make the lengths of the paths from all the paths of the plurality of parallel-connected switch modules 410 until they merge substantially equal. The same effect is achieved for the V-phase parallel connection bus bar 42O1 and the W-phase parallel connection bus bar 43O1.

[0354] In addition, in the present embodiment (the first embodiment), for the multiple (four) switch modules 410 connected in parallel, two switch modules 410 of two groups may be aligned in the X-axis direction, and two columns may be arranged in the other axial direction (Y-axis direction) perpendicular to the X-axis direction. The same applies to the multiple (four) switch modules 420 and the multiple (four) switch modules 430. In addition, the U-phase parallel connection busbar 41O1 is configured to be substantially symmetric with respect to the vertical plane at the central position of the two switch modules 410 in the X-axis direction. In addition, the U-phase parallel connection busbar 41O1 may be configured to be substantially symmetric with respect to the vertical plane at the central position of the two groups in the Y-axis direction. Further, the U-phase parallel connection busbar 41O1 may be configured such that the connection portion with the wiring (U-phase output busbar 41O2) up to the U-phase output terminal 41T is at the central position among the four switch modules 410 included in the two groups in the X-axis direction and the Y-axis direction. The same applies to the V-phase parallel connection busbar 42O1 and the W-phase parallel connection busbar 43O1.

[0355] Accordingly, in the U-phase parallel connection busbar 41O1, specifically, the lengths of the respective paths until the paths of the multiple (four) switch modules 410 connected in parallel merge can be made substantially equal. Therefore, in the power conversion device 1, specifically, the inductances of the paths through the respective semiconductor switches 410s can be made substantially equal. The same effect is achieved for the V-phase parallel connection busbar 42O1 and the W-phase parallel connection busbar 43O1.

[0356] In addition, in the present embodiment (second embodiment), the power conversion device 1 includes a smoothing circuit 20, an inverter circuit 40, and output terminals 40T. Specifically, the inverter circuit 40 includes a U-phase circuit 41, which is formed by connecting in parallel a plurality of switching modules 410 each including a plurality of semiconductor switches 410s connected in series in upper and lower arms, and connecting the connection points (AC output terminals 410O) of the upper and lower arms of each of the plurality of switching modules 410 to each other. Similarly, the inverter circuit 40 includes a V-phase circuit 42, which is formed by connecting in parallel a plurality of switching modules 420 each including a plurality of semiconductor switches 420s connected in series in upper and lower arms, and connecting the connection points (AC output terminals 420O) of the upper and lower arms of each of the plurality of switching modules 420 to each other. Similarly, the inverter circuit 40 includes a W-phase circuit 43, which is formed by connecting in parallel a plurality of switching modules 430 each including a plurality of semiconductor switches 430s connected in series in upper and lower arms, and connecting the connection points (AC output terminals 430O) of the upper and lower arms of each of the plurality of switching modules 430 to each other. That is, the inverter circuit 40 includes a bridge circuit formed by connecting in parallel a plurality of phases through output circuits (U-phase circuit 41, V-phase circuit 42, and W-phase circuit 43). And, the inverter circuit 40 outputs a prescribed alternating current based on the direct current input from the smoothing circuit 20. In addition, the output terminals 40T output the prescribed alternating current from the inverter circuit 40 to the outside. In addition, the inverter circuit 40 includes a positive-side DC bus 40P that connects the positive-side terminals 410P, 420P, 430P of the plurality of switching modules 410, 420, 430 to each other, and a negative-side DC bus 40N that connects the negative-side terminals 410N, 420N, 430N of the plurality of switching modules 410, 420, 430 to each other. In addition, the inverter circuit 40 includes a U-phase parallel connection bus 41O1 that connects the AC output terminals 410O of the plurality of switching modules 410 to each other. Similarly, the inverter circuit 40 includes a V-phase parallel connection bus 42O1 that connects the AC output terminals 420O of the plurality of switching modules 420 to each other. Similarly, the inverter circuit 40 includes a W-phase parallel connection bus 43O1 that connects the AC output terminals 430O of the plurality of switching modules 430 to each other. In addition, the positive-side DC bus 40P and the negative-side DC bus 40N have a laminated structure laminated with an insulating layer 41I1, 42I1, 43I1 therebetween. In addition, the U-phase parallel connection bus 41O1 is configured such that the lengths of the respective power paths between the smoothing circuit 20 and the merging portions where the paths from the plurality of switching modules 410 merge through all of the arms (semiconductor switches 410s) included in the plurality of switching modules 410 are substantially equal.Moreover, the U-phase parallel connection busbar 41O1 is configured such that the current density of the entire path of each power path between the smoothing circuit 20 and the confluence part through all the bridge arms included in the plurality of switching modules 410 is substantially equal. Similarly, the V-phase parallel connection busbar 42O1 is configured such that the lengths of the respective power paths between the smoothing circuit 20 and the confluence part where the paths from the plurality of switching modules 420 merge are substantially equal through all the bridge arms (semiconductor switches 420s) included in the plurality of switching modules 420. Moreover, the V-phase parallel connection busbar 42O1 is configured such that the current density of the entire path of each power path between the smoothing circuit 20 and the confluence part is substantially equal through all the bridge arms included in the plurality of switching modules 420. Similarly, the W-phase parallel connection busbar 43O1 is configured such that the lengths of the respective power paths between the smoothing circuit 20 and the confluence part where the paths from the plurality of switching modules 430 merge are substantially equal through the bridge arms (semiconductor switches 430s) included in the plurality of switching modules 430. Moreover, the W-phase parallel connection busbar 43O1 is configured such that the current density of the entire path of each power path between the smoothing circuit 20 and the confluence part is substantially equal through all the bridge arms included in the plurality of switching modules 430.

[0357] Accordingly, in the inverter circuit 40, it is possible to equalize the lengths of all the paths between the DC input and the AC output confluence part and the current density of the entire path of each path. Therefore, in the power conversion device 1, for the power paths passing through the plurality of switching modules 410 respectively, it is possible to make the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T) substantially equal. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 410s (switching modules 410), and thus can achieve current equalization. The same applies to the plurality of switching modules 420. Therefore, in the power conversion device 1, for the power paths passing through the plurality of switching modules 420 respectively, it is possible to make the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T (V-phase output terminal 42T) substantially equal. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 420s (switching modules 420), and thus can achieve current equalization. The same applies to the plurality of switching modules 430. Therefore, in the power conversion device 1, for the power paths passing through the plurality of switching modules 430 respectively, it is possible to make the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T (W-phase output terminal 43T) substantially equal. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 430s (switching modules 430) respectively, and thus can achieve current equalization.

[0358] Further, in the present embodiment (second embodiment), the U-phase parallel connection bus bar 41O1 can be configured such that the current density of each power path of each of the plurality of switching modules 410 becomes substantially equal in the common portion of the lengths of the power paths. Also, the U-phase parallel connection bus bar 41O1 can be configured such that the current density of the portion other than that, i.e., the portion corresponding to the difference in the lengths of each power path, 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 applies to the V-phase parallel connection bus bar 42O1 and the W-phase parallel connection bus bar 43O1.

[0359] Accordingly, in the inverter circuit 40, it is possible to make the current density of each path of all the paths between the DC input and the AC input merging portion substantially equal over the entire path.

[0360] Further, in the present embodiment (second embodiment), the smoothing circuit 20 and the inverter circuit 40 can be arranged and disposed in one axial direction (X-axis direction). Also, the plurality of switching modules 410 can be arranged and disposed in the X-axis direction. The same can apply to the plurality of switching modules 420 and the plurality of switching modules 430. Further, the U-phase parallel connection bus bar 41O1 can include a plurality of legs 41O1a that are provided to extend in the vertical direction (Z-axis direction) from the connection points (AC output terminals 410O) of the upper and lower bridge arms of each of the plurality of switching modules 410 and have substantially the same length and substantially the same cross-sectional area. The U-phase parallel connection bus bar 41O1 can include a connection portion 41O1b that connects the plurality of legs 41O1a so as to extend in the X-axis direction. Also, the connection portion 41O1b can be connected to the wiring (U-phase output bus bar 41O2) up to the output terminal 40T (U-phase output terminal 41T) at an end portion away from the smoothing circuit 20 in the X-axis direction. And the connection portion 41O1b is configured such that the current density thereof 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 passing through each of the plurality of switching modules 410. The same can apply to the V-phase parallel connection bus bar 42O1 and the W-phase parallel connection bus bar 43O1.

[0361] Accordingly, in the inverter circuit 40, specifically, it is possible to make the lengths of all the power paths between the DC input and the AC output merging portion and the current density of each power path over the entire path substantially equal.

[0362] In addition, in the present embodiment (second embodiment), the plurality of switch modules 410 may be arranged in two columns in another axial direction (Y-axis direction) perpendicular to the X-axis direction, with two groups arranged in one axial direction (X-axis direction). Further, the connection portion 41O1b of the U-phase parallel connection bus bar 41O1 may connect the plurality of legs 41O1a to each other so as to extend in the X-axis direction and the Y-axis direction.

[0363] Accordingly, in the inverter circuit 40, specifically, it is possible to make the lengths of all the power paths between the DC input and the AC output confluence portion and the current density of each power path over the entire path substantially equal.

[0364] In addition, in the present embodiment (third embodiment), the power conversion device 1 includes a smoothing circuit 20, an inverter circuit 40, and output terminals 40T. Specifically, the inverter circuit 40 includes a U-phase circuit 41, which is constituted by a plurality of switching modules 410 connected in parallel, each of which is formed by a series connection of upper and lower bridge arms including a plurality of semiconductor switches 410s, and the connection points (AC output terminals 410O) of the upper and lower bridge arms of each of the plurality of switching modules 410 are connected to each other. Similarly, the inverter circuit 40 includes a V-phase circuit 42, which is constituted by a plurality of switching modules 420 connected in parallel, each of which is formed by a series connection of upper and lower bridge arms including a plurality of semiconductor switches 420s, and the connection points (AC output terminals 420O) of the upper and lower bridge arms of each of the plurality of switching modules 420 are connected to each other. Similarly, the inverter circuit 40 includes a W-phase circuit 43, which is constituted by a plurality of switching modules 430 connected in parallel, each of which is formed by a series connection of upper and lower bridge arms including a plurality of semiconductor switches 430s, and the connection points (AC output terminals 430O) of the upper and lower bridge arms of each of the plurality of switching modules 430 are connected to each other. That is, the inverter circuit 40 includes a bridge circuit constituted by connecting a plurality of phases in parallel through output circuits (U-phase circuit 41, V-phase circuit 42, and W-phase circuit 43). And, the inverter circuit 40 outputs a prescribed alternating current based on the direct current input from the smoothing circuit 20. In addition, the output terminals 40T output the prescribed alternating current from the inverter circuit 40 to the outside. In addition, the inverter circuit 40 includes a positive-side DC bus 40P that connects the positive-side terminals 410P, 420P, 430P of the plurality of switching modules 410, 420, 430 to each other, and a negative-side DC bus 40N that connects the negative-side terminals 410N, 420N, 430N of the plurality of switching modules 410, 420, 430 to each other. In addition, the inverter circuit 40 includes a U-phase parallel connection bus 41O1 that connects the AC output terminals 410O of the plurality of switching modules 410 to each other. In addition, the positive-side DC bus 40P, the negative-side DC bus 40N, and the U-phase parallel connection bus 41O1 have a laminated structure laminated with insulating layers 41I1, 41I2 therebetween. Similarly, the inverter circuit 40 includes a V-phase parallel connection bus 42O1 that connects the AC output terminals 420O of the plurality of switching modules 420 to each other. In addition, the positive-side DC bus 40P, the negative-side DC bus 40N, and the V-phase parallel connection bus 42O1 have a laminated structure laminated with insulating layers 42I1, 42I2 therebetween. Similarly, the inverter circuit 40 includes a W-phase parallel connection bus 43O1 that connects the AC output terminals 430O of the plurality of switching modules 430 to each other. In addition, the positive-side DC bus 40P, the negative-side DC bus 40N, and the W-phase parallel connection bus 43O1 have a laminated structure laminated with insulating layers 43I1, 43I2 therebetween.Moreover, the connection portion of the U-phase parallel connection bus 41O1 and the wiring (U-phase output bus 41O2) up to the output terminal 40T (U-phase output terminal 41T) is provided at a position farther from the smoothing circuit 20 than the semiconductor switch 410s of all the bridge arms (semiconductor switches 410s) included in the plurality of switch modules 410 that is farthest from the smoothing circuit 20. Similarly, the connection portion of the V-phase parallel connection bus 42O1 and the wiring up 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 of all the bridge arms (semiconductor switches 420s) included in the plurality of switch modules 420 that is farthest from the smoothing circuit 20. Similarly, the connection portion of the W-phase parallel connection bus 43O1 and the wiring up 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 of all the bridge arms (semiconductor switches 430s) included in the plurality of switch modules 430 that is farthest from the smoothing circuit 20.

[0365] Accordingly, with the lamination structuring of the bus bar of the inverter circuit 40, it is possible to substantially equalize the current density of all the power paths between the DC input and the AC input junction of the inverter circuit 40. Further, with the arrangement of the connection portion between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2, the junction where the paths from the respective switch modules 410 merge is set at a position farthest from the semiconductor switch 410s of the smoothing circuit 20. That is, it is possible to make the lengths of all the power paths between the DC input and the AC output junction in the inverter circuit 40 through the respective switch modules 410 substantially equal. Therefore, the power conversion device 1 can make the inductances of all the power paths of one cycle between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T) through the respective switch modules 410 substantially equal. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 410s (switch modules 410), and thus can achieve current equalization. The same applies to the plurality of switch modules 420. Therefore, the power conversion device 1 can make the inductances of all the power paths of one cycle between the smoothing circuit 20 and the output terminal 40T (V-phase output terminal 42T) through the respective switch modules 420 substantially equal. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 420s (switch modules 420), and thus can achieve current equalization. The same applies to the plurality of switch modules 430. Therefore, the power conversion device 1 can make the inductances of all the power paths of one cycle between the smoothing circuit 20 and the output terminal 40T (W-phase output terminal 43T) through the respective switch modules 430 substantially equal. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 430s (switch modules 430), and thus can achieve current equalization.

[0366] Further, in the present embodiment (third 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 in the X-axis direction at a position farther from the smoothing circuit 20 than the switch module 410, which is the farthest from the smoothing circuit 20 among the plurality of switch modules 410. The same applies 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.

[0367] For example, multiple switch modules 410 can be 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 multiple switch modules 420 and the multiple switch modules 430. Moreover, the connection portion between the U-phase parallel connection busbar 41O1 and the U-phase output busbar 41O2 can be arranged at a position farther from the smoothing circuit 20 of the two groups in the X-axis direction and at a position approximately in the center of the two groups in the Y-axis direction. The same applies to the connection portion between the V-phase parallel connection busbar 42O1 and the V-phase output busbar 42O2 and the connection portion between the W-phase parallel connection busbar 43O1 and the W-phase output busbar 43O2.

[0368] Accordingly, in the inverter circuit 40, specifically, the lengths of the power paths between the DC input and the confluence portion of the AC output can be made substantially equal.

[0369] In addition, in the present embodiment (the fourth embodiment), the power conversion device 1 includes a smoothing circuit 20, an inverter circuit 40, and output terminals 40T. Specifically, the inverter circuit 40 includes a U-phase circuit 41, which is formed by connecting in parallel a plurality of switching modules 410 each including upper and lower arms in which a plurality of semiconductor switches 410s are connected in series, and connecting the connection points (AC output terminals 410O) of the upper and lower arms of each of the plurality of switching modules 410 to each other. Similarly, the inverter circuit 40 includes a V-phase circuit 42, which is formed by connecting in parallel a plurality of switching modules 420 each including upper and lower arms in which a plurality of semiconductor switches 420s are connected in series, and connecting the connection points (AC output terminals 420O) of the upper and lower arms of each of the plurality of switching modules 420 to each other. Similarly, the inverter circuit 40 includes a W-phase circuit 43, which is formed by connecting in parallel a switching module 430 including upper and lower arms in which a plurality of semiconductor switches 430s are connected in series, and connecting the connection points (AC output terminals 430O) of the upper and lower arms of each of the plurality of switching modules 430 to each other. That is, the inverter circuit 40 includes a bridge circuit formed by connecting in parallel a plurality of phases through output circuits (U-phase circuit 41, V-phase circuit 42, and W-phase circuit 43). And the inverter circuit 40 outputs a prescribed alternating current based on the direct current input from the smoothing circuit 20. In addition, the output terminals 40T output the prescribed alternating current from the inverter circuit 40 to the outside. In addition, the inverter circuit 40 includes a positive-side DC bus 40P that connects the positive-side terminals 410P, 420P, 430P of the plurality of switching modules 410, 420, 430 to each other, and a negative-side DC bus 40N that connects the negative-side terminals 410N, 420N, 430N of the plurality of switching modules 410, 420, 430 to each other. In addition, the inverter circuit 40 includes a U-phase parallel connection bus 41O1 that connects the AC output terminals 410O of the plurality of switching modules 410 to each other. In addition, the positive-side DC bus 40P, the negative-side DC bus 40N, and the U-phase parallel connection bus 41O1 have a laminated structure laminated with insulating layers 41I1, 41I2 therebetween. Similarly, the inverter circuit 40 includes a V-phase parallel connection bus 42O1 that connects the AC output terminals 420O of the plurality of switching modules 420 to each other. In addition, the positive-side DC bus 40P, the negative-side DC bus 40N, and the V-phase parallel connection bus 42O1 have a laminated structure laminated with insulating layers 42I1, 42I2 therebetween. Similarly, the inverter circuit 40 includes a W-phase parallel connection bus 43O1 that connects the AC output terminals 430O of the plurality of switching modules 430 to each other. In addition, the positive-side DC bus 40P, the negative-side DC bus 40N, and the W-phase parallel connection bus 43O1 have a laminated structure laminated with insulating layers 43I1, 43I2 therebetween.Moreover, the connection portion of the U-phase parallel connection bus bar 41O1 and the wiring (U-phase output bus bar 42O2) up 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 bridge arms (semiconductor switches 410s) included in the plurality of switching modules 410. Similarly, the connection portion of the V-phase parallel connection bus bar 42O1 and the wiring (V-phase output bus bar 42O2) up 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 bridge arms (semiconductor switches 420s) included in the plurality of switching modules 420. Similarly, the connection portion of the W-phase parallel connection bus bar 43O1 and the wiring (W-phase output bus bar 43O2) up 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 bridge arms (semiconductor switches 430s) included in the plurality of switching modules 430.

[0370] Accordingly, with the lamination structuring of the bus bar of the inverter circuit 40, it is possible to substantially equalize the current density of all the power paths between the DC input and the AC input merging section of the inverter circuit 40. Moreover, with the arrangement of the connection section between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2, in the actual space, it is possible to make the direction of the current in the U-phase positive side DC bus bar 41P opposite to the direction of the current in the U-phase parallel connection bus bar 41O1. Similarly, it is possible to make the direction of the current in the U-phase parallel connection bus bar 41O1 opposite to the direction of the current in the U-phase negative side DC bus bar 41N. Therefore, by the currents with substantially the same current density flowing in opposite directions, the generated magnetic fields cancel each other out, and it is possible to reduce 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 be very small. As a result, it is possible to reduce the difference in the inductance of all the power paths between the DC input and the AC input merging section passing through the plurality of switching modules 410, and thus it is possible to equalize the inductance between the power paths. Therefore, the power conversion device 1 can suppress the difference in the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T (U-phase output terminal 41T) passing through each of the plurality of switching modules 410 to be very small. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 410s (switching modules 410), and thus it is possible to equalize the current. The same applies to the plurality of switching modules 420. Therefore, the power conversion device 1 can suppress the difference in the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T (V-phase output terminal 42T) passing through each of the plurality of switching modules 420 to be very small. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 420s (switching modules 420), and thus it is possible to equalize the current. The same applies to the plurality of switching modules 430. Therefore, the power conversion device 1 can suppress the difference in the inductance of one cycle of the power path between the smoothing circuit 20 and the output terminal 40T (W-phase output terminal 43T) passing through each of the plurality of switching modules 430 to be very small. Thereby, the power conversion device 1 can suppress the current imbalance of the plurality of semiconductor switches 430s (switching modules 430), and thus it is possible to equalize the current.

[0371] In addition, in the present embodiment (the fourth embodiment), the smoothing circuit 20 and the inverter circuit 40 may be arranged and disposed in one axial direction (the X-axis direction). Moreover, the connection portion between the U-phase parallel connection bus bar 41O1 and the U-phase output bus bar 41O2 may be disposed 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 applies 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.

[0372] For example, the plurality of switch modules 410 are arranged and disposed in two columns in another axial direction (the Y-axis direction) perpendicular to the X-axis direction, with two groups arranged in the X-axis direction when viewed from above. The same applies to the plurality of switch modules 420 and the plurality of switch modules 430. Moreover, the connection portion between the U-phase parallel connection bus bar 41O1 and the wiring (U-phase output bus bar 41O2) up to the U-phase output terminal 41T may be disposed at a position closer to the smoothing circuit 20 than the end portions of the two groups closer to the smoothing circuit 20 in the X-axis direction. The same applies to the connection portion between the V-phase parallel connection bus bar 42O1 and the wiring (V-phase output bus bar 42O2) up to the V-phase output terminal 42T, and the connection portion between the W-phase parallel connection bus bar 43O1 and the wiring (W-phase output bus bar 43O2) up to the W-phase output terminal 43T.

[0373] Specifically, by this means, it is possible to make the directions of the currents of the U-phase positive-side DC bus bar 41P and the U-phase parallel connection bus bar 41O1, and the directions of the currents of the U-phase parallel connection bus bar 41O1 and the U-phase negative-side DC bus bar 41N in the actual space be opposite to each other respectively. Similarly, it is possible to make the directions of the currents of the V-phase positive-side DC bus bar 42P and the V-phase parallel connection bus bar 42O1, and the directions of the currents of the V-phase parallel connection bus bar 42O1 and the V-phase negative-side DC bus bar 42N in the actual space be opposite to each other respectively. Similarly, it is possible to make the directions of the currents of the W-phase positive-side DC bus bar 43P and the W-phase parallel connection bus bar 43O1, and the directions of the currents of the W-phase parallel connection bus bar 43O1 and the W-phase negative-side DC bus bar 43N in the actual space be opposite to each other respectively.

[0374] As described above, the embodiments have been described in detail, but the present invention is not limited to the specific embodiments, and various modifications / changes can be made within the scope of the gist described in the claims.

[0375] Description of Reference Numerals

[0376] 1 Power conversion device

[0377] 10 Rectifier circuit

[0378] 20 smoothing circuit

[0379] 20I1, 20I2 insulating layer

[0380] 20N negative side bus bar

[0381] 20P positive side bus bar

[0382] 20PN laminated bus bar

[0383] 21 smoothing capacitor

[0384] 21P positive side terminal

[0385] 21N negative side terminal

[0386] 30 fuse

[0387] 40 inverter circuit

[0388] 40N negative side DC bus bar

[0389] 40P positive side DC bus bar

[0390] 40PN laminated bus bar

[0391] 40T output terminal

[0392] 41 U-phase circuit (output circuit)

[0393] 41I1, 41I2 insulating layer

[0394] 41N U-phase negative side DC bus bar

[0395] 41O U-phase AC bus bar

[0396] 41O1 U-phase parallel connection bus bar

[0397] 41O2 U-phase output bus bar

[0398] 41P U-phase positive side DC bus bar

[0399] 41PN, 41PNO U-phase laminated bus bar

[0400] 41T U-phase output terminal

[0401] 42 V-phase circuit (output circuit)

[0402] 42I1, 42I2 insulating layer

[0403] 42N V-phase negative side DC bus bar

[0404] 42O V-phase AC bus bar

[0405] Busbar for V-phase parallel connection

[0406] Busbar for V-phase output

[0407] DC busbar for V-phase positive electrode side

[0408] Laminated busbar for V-phase (42PN, 42PNO)

[0409] Output terminal for V-phase (42T)

[0410] W-phase circuit (output circuit) (43)

[0411] Insulation layer (43I1, 43I2)

[0412] DC busbar for W-phase negative electrode side (43N)

[0413] AC busbar for W-phase (43O)

[0414] Busbar for W-phase parallel connection (43O1)

[0415] Busbar for W-phase output (43O2)

[0416] DC busbar for W-phase positive electrode side (43P)

[0417] Laminated busbar for W-phase (43PN, 43PNO)

[0418] Output terminal for W-phase (43T)

[0419] Switch module (switch bridge arm) (410 - 416)

[0420] Negative electrode side terminal (410N - 416N)

[0421] AC output terminal (connection point) (410O - 416O)

[0422] Positive electrode side terminal (410P - 416P)

[0423] Semiconductor switch (410s, 411s1 - 416s1, 411s2 - 416s2)

[0424] Freewheeling diode (411d1 - 416d1, 411d2 - 416d2)

[0425] Switch module (switch bridge arm) (420 - 426)

[0426] Negative electrode side terminal (420N - 426N)

[0427] AC output terminal (connection point) (420O - 426O)

[0428] Positive electrode side terminal (420P - 426P)

[0429] 420s, 421s1 to 426s1, 421s2 to 426s2 semiconductor switches

[0430] 421d1 to 426d1, 421d2 to 426d2 freewheeling diodes

[0431] 430 to 436 switching modules (switching bridge arms)

[0432] 430N to 436N negative side terminals

[0433] 430O to 436O AC output terminals (connection points)

[0434] 430P to 436P positive side terminals

[0435] 430s, 431s1 to 436s1, 431s2 to 436s2 semiconductor switches

[0436] 431d1 to 436d1, 431d2 to 436d2 freewheeling diodes

Claims

1. A power conversion device, comprising: a smoothing circuit; an inverter circuit including a bridge circuit that outputs a prescribed alternating current based on direct current input from the smoothing circuit, the bridge circuit being configured by connecting in parallel a plurality of switching arms each formed by connecting upper and lower arms including a plurality of semiconductor switches in series, and connecting in parallel a plurality of phases of output circuits in which connection points of the upper and lower arms of the plurality of switching arms are connected to each other; and output terminals that output the prescribed alternating current to the outside, wherein the inverter circuit includes a positive-side DC bus that connects positive-side terminals of the plurality of switching arms to each other, a negative-side DC bus that connects negative-side terminals of the plurality of switching arms to each other, and a parallel connection bus that connects connection points of the upper and lower arms of the plurality of switching arms to each other, the positive-side DC bus, the negative-side DC bus, and the parallel connection bus have a laminated structure laminated with an insulating layer therebetween, a connection portion of the parallel connection bus and wiring up to the output terminals is provided at a position farther from the smoothing circuit than the arm among all the arms included in the plurality of switching arms that is farthest from the smoothing circuit, the smoothing circuit and the inverter circuit are arranged and disposed in one axial direction, the plurality of switching arms are arranged and disposed in the one axial direction, in the one axial direction, the connection portion is arranged at a position farther from the smoothing circuit than the switching arm among the plurality of switching arms that is farthest from the smoothing circuit.

2. The power conversion device according to claim 1, wherein the plurality of switching arms are arranged in two rows in another axial direction perpendicular to the one axial direction with two groups each arranged in the one axial direction, in the one axial direction, the connection portion is arranged at a position farther from the smoothing circuit than the ends of the two groups that are far from the smoothing circuit, and in the other axial direction, the connection portion is arranged at a substantially central position of the two groups.

3. A power conversion device, comprising: a smoothing circuit; an inverter circuit including a bridge circuit that outputs a prescribed alternating current based on direct current input from the smoothing circuit, the bridge circuit being configured by connecting in parallel a plurality of switching arms each formed by connecting upper and lower arms including a plurality of semiconductor switches in series, and connecting in parallel a plurality of phases of output circuits in which connection points of the upper and lower arms of the plurality of switching arms are connected to each other; and output terminals that output the prescribed alternating current to the outside, wherein the inverter circuit includes a positive-side DC bus that connects positive-side terminals of the plurality of switching arms to each other, a negative-side DC bus that connects negative-side terminals of the plurality of switching arms to each other, and a parallel connection bus that connects connection points of the upper and lower arms of the plurality of switching arms to each other, the positive-side DC bus and the negative-side DC bus have a laminated structure laminated with an insulating layer therebetween, The bus bar for parallel connection is configured as follows: the lengths of the respective paths between the smoothing circuit and the confluence part where all the paths from all of the above-mentioned bridge arms included in the plurality of the above-mentioned switching bridge arms converge are substantially equal, and the current density throughout the entire path of each of the above-mentioned paths is substantially equal. The bus bar for parallel connection is configured as follows: the current density of the common part of the length of each of the above-mentioned paths is substantially equal, and the current density of the part other than the common part of the length of each of the above-mentioned paths is substantially equal to the current density of the positive-side DC bus bar and the negative-side DC bus bar. The above-mentioned smoothing circuit and the above-mentioned inverter circuit are arranged and configured in one axial direction. The plurality of the above-mentioned switching bridge arms are arranged and configured in the above-mentioned one axial direction. The bus bar for parallel connection includes: a plurality of legs, which are arranged to extend in the vertical direction from the connection points of the upper and lower bridge arms of each of the plurality of the above-mentioned switching bridge arms, and have substantially the same length and substantially the same cross-sectional area; and a connection part, which connects the plurality of legs to each other in a manner of extending in the above-mentioned one axial direction. The connection part is configured as follows: the end part far from the smoothing circuit in the above-mentioned one axial direction is connected to the wiring up to the output terminal, and the current density of each of the above-mentioned paths is made substantially equal to the current density of the positive-side DC bus bar and the negative-side DC bus bar.

4. The power conversion device according to claim 3, wherein, the plurality of the above-mentioned switching bridge arms are arranged in two groups arranged in one axial direction and arranged in two columns in another axial direction perpendicular to the above-mentioned one axial direction. The connection part connects the plurality of legs to each other in a manner of extending in the above-mentioned one axial direction and the above-mentioned another axial direction.

5. A power conversion device, comprising: a smoothing circuit; an inverter circuit, which includes a bridge circuit and outputs a prescribed alternating current based on the direct current input from the above-mentioned smoothing circuit. The bridge circuit is formed by a plurality of switching bridge arms connected in series by upper and lower bridge arms including a plurality of semiconductor switches and the output circuits in which the connection points of the upper and lower bridge arms of each of the plurality of the above-mentioned switching bridge arms are connected to each other are connected in parallel for a plurality of phases; and an output terminal, which outputs the above-mentioned prescribed alternating current to the outside. The above-mentioned inverter circuit includes: a positive-side DC bus bar, which connects the positive-side terminals of the plurality of the above-mentioned switching bridge arms to each other; a negative-side DC bus bar, which connects the negative-side terminals of the plurality of the above-mentioned switching bridge arms to each other; and a bus bar for parallel connection, which connects the connection points of the upper and lower bridge arms of each of the plurality of the above-mentioned switching bridge arms to each other. The above-mentioned positive-side DC bus bar, the above-mentioned negative-side DC bus bar, and the above-mentioned bus bar for parallel connection have a laminated structure laminated with an insulating layer therebetween. The connection part of the above-mentioned bus bar for parallel connection with the wiring up to the output terminal is provided at a position closer to the smoothing circuit than the bridge arm closest to the smoothing circuit among all the bridge arms included in the plurality of the above-mentioned switching bridge arms. The above smoothing circuit and the above inverter circuit are arranged and configured in one axial direction, A plurality of the above switch bridge arms are arranged and configured in the above one axial direction, In the above one axial direction, the above connection part is arranged at a position closer to the above smoothing circuit than the above switch bridge arm closest to the above smoothing circuit among the plurality of the above switch bridge arms.

6. The power conversion device according to claim 5, wherein, The plurality of the above switch bridge arms are arranged in two columns in another axial direction perpendicular to the above one axial direction in such a manner that two groups each arranged in the above one axial direction are arranged, In the above one axial direction, the above connection part is arranged at a position closer to the above smoothing circuit than the ends of the above two groups closer to the above smoothing circuit.

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