Patent Publication Number: US-2022216724-A1

Title: Laminated bus bar, power converter, power conversion device, and uninterruptible power supply device

Description:
TECHNICAL FIELD 
     The present disclosure relates to a laminated bus bar, a power converter, a power conversion device, and an uninterruptible power supply device. 
     BACKGROUND ART 
     In a power conversion device, a laminated bus bar is frequently used in a main wiring circuit between a semiconductor module that constitute a power converter and a power supply (for example, see Japanese Patent Laying-Open No. 2019-21664 (Patent Literature 1)). The laminated bus bar has a structure in which a plurality of insulating plates are alternately stacked for a plurality of conductive plates that constitute a wiring circuit. The laminated bus bar is used for reducing wiring inductance. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Laying-Open No. 2019-21664 
     SUMMARY OF INVENTION 
     Technical Problem 
     In a power conversion device having a plurality of power converters, power converters having a common configuration are sometimes used for the power converters, in view of reducing production costs. For example, in a case of an uninterruptible power supply device, it has been contemplated that a converter and an inverter electrically connected in series between an AC power supply and a load are configured with common power converters. 
     In this case, a power converter that configures a converter and a power converter that configures an inverter are arranged in alignment on a stage. Then, two conductive members that respectively configure a DC positive bus and a DC negative bus are disposed between two power converters. A positive DC terminal and a negative DC terminal formed at a laminated bus bar of each power converter are respectively connected to two conductive members. 
     In the configuration above, when fuses are connected between the positive DC terminal of each power converter and the DC positive bus and between the negative DC terminal of each converter and the DC negative bus, in total, four fuses are arranged in a space between two power converters. Here, if a total of four fuses are arranged in alignment in a depth direction and a normal direction of the stage, a total of four fuses can be provided without expanding the space. 
     However, it is necessary to form the conductive members into a complicated shape in order to attach two fuses to one conductive member so as to be displaced from each other in a state in which two laminated bus bars having the same configuration face each other with the space interposed therebetween. With this configuration, attachment of fuses to the conductive members is difficult and, consequently, workability in installation and replacement of fuses may be reduced. In order to implement a complicated shape, the processing cost for the conductive members may be increased. 
     Moreover, in the arrangement of a plurality of fuses in alignment in a depth direction, a fuse on the back side is less visible, so that it may be difficult to visually check whether fuses are damaged in use of the power conversion device. 
     If laminated bus bars of different configurations are employed for a power converter that configures a converter and a power converter that configures an inverter, the inconvenience described above can be avoided, but this is against the purpose of achieving commonality of power converters. 
     The present disclosure is made in consideration of the problem above and an object of the present disclosure is to provide a laminated bus bar, a power converter, a power conversion device, and an uninterruptible power supply device, in which commonality of power converts can be achieved with a simple configuration. 
     Solution to Problem 
     A laminated bus bar according to an embodiment of the present disclosure is for use in a power converter capable of bidirectional power conversion. The laminated bus bar has a flat plate portion having a length direction, a width direction orthogonal to the length direction, and a thickness direction orthogonal to the length direction and the width direction. The flat plate portion includes a first conductive plate, a second conductive plate, a third conductive plate, and first to fourth insulating plates. The first conductive plate has a first AC terminal and a second AC terminal. The second conductive plate has a first positive DC terminal and a second positive DC terminal. The third conductive plate has a first negative DC terminal and a second negative DC terminal. The first to fourth insulating plates are alternately stacked in the thickness direction for the first to third conductive plates. The flat plate portion has a first end portion in the length direction of the flat plate portion and a second end portion on an opposite side to the first end portion of the flat plate portion. In the first end portion, the first AC terminal protrudes from the first conductive plate in the length direction. The first positive DC terminal protrudes from the second conductive plate in the length direction. The first negative DC terminal protrudes from the third conductive plate in the length direction. The first AC terminal, the first positive DC terminal, and the first negative DC terminal are arranged in alignment in this order from a third end portion in the width direction of the flat plate portion toward a fourth end portion on an opposite side to the third end portion. In the second end portion, the second AC terminal protrudes from the first conductive plate in the length direction. The second positive DC terminal protrudes from the second conductive plate in the length direction. The second negative DC terminal protrudes from the third conductive plate in the length direction. The second AC terminal, the second negative DC terminal, and the second positive DC terminal are arranged in alignment in this order from the third end portion toward the fourth end portion of the flat plate portion. ADVANTAGEOUS EFFECTS OF INVENTION 
     The present disclosure can provide a laminated bus bar, a power converter, a power conversion device, and an uninterruptible power supply device, in which commonality of power converts can be achieved with a simple configuration. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram showing a main circuit configuration of a power conversion device according to an embodiment. 
         FIG. 2  is a block diagram showing a circuit configuration of a power converter according to the embodiment. 
         FIG. 3  is a block diagram showing a circuit configuration of a power converter according to the embodiment. 
         FIG. 4  is a diagram schematically showing a connection relation between the power converter and a control device according to the embodiment. 
         FIG. 5  is a front view of an uninterruptible power supply device according to the embodiment. 
         FIG. 6  is a top view of the uninterruptible power supply device according to the embodiment. 
         FIG. 7  is an external perspective view of the power converter. 
         FIG. 8  is a plan view showing a configuration of a laminated bus bar. 
         FIG. 9  is an exploded perspective view of a flat plate portion of the laminated bus bar. 
         FIG. 10  is a perspective view of a power conversion unit as viewed from a first direction on the second power converter side. 
         FIG. 11  is a perspective view of the power conversion unit as viewed from a second direction on the first power converter side. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present invention will be described in detail below with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference signs and a description thereof will basically not be repeated. 
     Main Circuit Configuration of Power Conversion Device 
       FIG. 1  is a block diagram illustrating a main circuit configuration of a power conversion device according to an embodiment. The power conversion device according to the present embodiment is typically applicable to an uninterruptible power supply device  100 . 
     Referring to  FIG. 1 , uninterruptible power supply device  100  is connected between a commercial AC power supply  5  and a load  6 . Commercial AC power supply  5  supplies three-phase AC power to uninterruptible power supply device  100 . Uninterruptible power supply device  100  supplies three-phase AC power to load  6 . 
     Specifically, commercial AC power supply  5  supplies three-phase AC voltages VR, VS, and VT having a commercial frequency to uninterruptible power supply device  100  through an R-phase line RL, an S-phase line SL, and a T-phase line TL. Uninterruptible power supply device  100  receives three-phase AC voltages VR, VS, and VT from commercial AC power supply  5  and outputs three-phase AC voltages VU, VV, and VW having a commercial frequency to load  6  through a U-phase line UL, a V-phase line VL, and a W-phase line WL. 
     Uninterruptible power supply device  100  includes reactors L 1  to L 3  and L 11  to L 13 , capacitors C 1  to C 3  and C 11  to C 13 , power conversion units  21  to  23 , a DC positive bus PL, a DC negative bus NL, a battery  7 , and a control device  9 . 
     Reactors L 1  to L 3  and capacitors C 1  to C 3  constitute a three-phase LC filter circuit. This LC filter circuit is a low-pass filter and functions as an input filter for preventing harmonics from flowing to commercial AC power supply  5 . 
     Reactors L 11  to L 13  and capacitors C 11  to C 13  constitute a three-phase LC filter circuit. This LC filter circuit is a low-pass filter and functions as an output filter for preventing harmonics from flowing to load  6 . 
     Power conversion units  21  to  23  convert three-phase AC voltages VR, VS, and VT supplied from commercial AC power supply  5  through the input filter into DC voltage and converts the DC voltage into three-phase AC voltages VU, VV, and VW. Power conversion units  21  to  23  supply three-phase AC voltages VU, VV, and VW to load  6  through the output filter. 
     Specifically, power conversion unit  21  has a converter  1 R, DC buses PL 1  and NL 1 , an inverter  2 U, and fuses FP 1 , FP 2 , FN 1 , and FN 2 . Power conversion unit  22  has a converter  1 S, DC buses PL 2  and NL 2 , an inverter  2 V, and fuses FP 3 , FP 4 , FN 3 , and FN 4 . Power conversion unit  23  has a converter  1 T, DC buses PL 3  and NL 3 , an inverter  2 WV, and fuses FP 5 , FP 6 , FN 5 , and FN 6 . 
     Each of converters  1 R,  1 S, and  1 T has an AC terminal AC 2 , a positive DC terminal (that is, high potential-side DC terminal) BP 1  and a negative DC terminal (that is, low potential-side DC terminal) BN 1 . Each of inverters  2 U,  2 V, and  2 W has an AC terminal AC 1 , a positive DC terminal BP 2 , and a negative DC terminal BN 2 . Converters  1 R,  1 S, and  1 T and inverters  2 U,  2 V, and  2 W correspond to an embodiment of “power converter”. Converters  1 R,  1 S, and  1 T correspond to an embodiment of “first power converter”. Inverters  2 U,  2 V, and  2 W correspond to an embodiment of “second power converter”. 
     AC terminal AC 2  of converter  1 R receives R-phase voltage VU from R-phase line RL through the input filter (capacitor C 1  and reactor L 1 ). Converter  1 R converts R-phase voltage VR into DC voltage and outputs the DC voltage to between DC terminals BP 1  and BN 1 . 
     AC terminal AC 2  of converter  1 S receives S-phase voltage VS from S-phase line SL through the input filter (capacitor C 2  and reactor L 2 ). Converter  1 S converts S-phase voltage VS into DC voltage and outputs the DC voltage to between DC terminals BP 1  and BN 1 . 
     AC terminal AC 2  of converter  1 T receives T-phase voltage VT from T-phase line RL through the input filter (capacitor C 3  and reactor L 3 ). Converter  1 T converts T-phase voltage VT into DC voltage and outputs the DC voltage to between DC terminals BP 1  and BN 1 . 
     One terminal of each of fuses FP 1 , FP 3 , and FP 5  is connected to positive DC terminal BP 1  of the corresponding one of converters  1 R,  15 , and  1 T. The other terminals of fuses FP 1 , FP 3 , and FP 5  are respectively connected to DC positive buses PL 1  to PL 3 . 
     One terminal of each of fuses FN 1 , FN 3 , and FN 5  is connected to negative DC terminal BN 1  of the corresponding one of converters  1 R,  1 S, and  1 T. The other terminals of fuses FN 1 , FN 3 , and FN 5  are respectively connected to DC negative buses NL 1  to NL 3 . 
     One terminal of each of fuses FP 2 , FP 4 , and FP 6  is connected to the corresponding one of DC positive buses PL 1  to PL 3 . The other terminals of fuses FP 2 , FP 4 , and FP 6  are respectively connected to positive DC terminals BP 2  of inverters  2 U,  2 V, and  2 W. 
     One terminal of each of fuses FN 2 , FN 4 , and FN 6  is connected to the corresponding one of DC negative buses NL 1  to NL 3 . The other terminals of fuses FN 2 , FN 4 , and FN 6  are respectively connected to negative DC terminals BN 2  of inverters  2 U,  2 V, and  2 W. 
     DC terminals BP 2  and BN 2  of inverter  2 U receive DC voltage from converter  1 R through DC buses PL 1  and NL 1 . Inverter  2 U converts DC voltage into U-phase voltage VU and outputs the U-phase voltage VU to AC terminal AC 1 . 
     DC terminals BP 2  and BN 2  of inverter  2 V receive DC voltage from converter  1 S through DC buses PL 2  and NL 2 . Inverter  2 V converts DC voltage into V-phase voltage VV and outputs the V-phase voltage VV to AC terminal AC 1 . 
     DC terminals BP 2  and BN 2  of inverter  2 W receive DC voltage from converter  1 T through DC buses PL 3  and NL 3 . Inverter  2 W converts DC voltage into W-phase voltage VW and outputs the W-phase voltage VW to AC terminal AC 1 . 
     DC positive bus PL is connected to DC positive buses PL 1  to PL 3 . DC negative bus NL is connected to DC negative buses NL 1  to NL 3 . DC buses PL and NL receive DC voltage generated in converters  1 R,  1 S, and  1 T. Battery  7  is connected between DC positive bus PL and DC negative bus NL. Battery  7  corresponds to an embodiment of “power storage device”. 
     Control device  9  controls converters  1 R,  1 S, and  1 T and inverters  2 U,  2 V, and  2 W in order to generate AC power to be supplied to load  6  in a sound state and a power failure of commercial AC power supply  5 . Control device  9  is mainly configured as, for example, a microcomputer including a CPU (Central Processing Unit) and a storage unit such as a ROM (Read Only Memory) and a RAM (Random Access Memory). Control device  9  controls converters  1 R,  1 S, and  1 T and inverters  2 U,  2 V, and  2 W by the CPU reading a program stored in advance in the ROM into the RAM and executing the program. 
     Specifically, in a sound state of commercial AC power supply  5 , control device  9  controls converters  1 R,  1 S, and  1 T and inverters  2 U,  2 V, and  2 W such that three-phase AC voltages VR, VS, and VT applied from commercial AC power supply  5  to AC terminal AC 2  are converted into DC voltage, the DC voltage is supplied to battery  7 , and the DC voltage is converted into three-phase AC voltages VU, VV, and VW and output to AC terminal AC 1 . 
     On the other hand, in a power failure of commercial AC power supply  5 , control device  9  stops the operation of converters  1 R,  1 S, and  1 T and controls inverters  2 U,  2 V, and  2 W such that DC voltage generated by DC power applied from battery  7  to DC terminals BP 2  and BN 2  is converted into three-phase AC voltages VU, VV, and VW and output to AC terminal AC 1 . 
     Circuit Configuration of Power Converter 
     In uninterruptible power supply device  100  shown in  FIG. 1 , power converters having a common structure can be used for converters  1 R,  1 S,  1 T and inverters  2 U,  2 V,  2 W. 
     Hereinafter, the structure of a converter according to the present embodiment will be described in detail. First, referring to  FIG. 2  to  FIG. 4 , a circuit configuration of the power converter according to the present embodiment is described. 
       FIG. 2  and  FIG. 3  are block diagrams showing a circuit configuration of power converter  10  according to the present embodiment.  FIG. 2  shows a configuration example of converter  1 R using power converter  10 . 
     Referring to  FIG. 2 , power converter  10  includes AC terminals AC 1  and AC 2 , positive DC terminals BP 1  and BP 2 , and negative DC terminals BN 1  and BN 2 . 
     AC input terminals AC 1  and AC 2  receive AC voltage from commercial AC power supply  5  or load  6 . In the example of converter  1 R, AC terminal AC 2  is connected to R-phase line RL and receives R-phase voltage VR from commercial AC power supply  5 . AC terminal AC 2  corresponds to an embodiment of “second AC terminal”. 
     Positive DC terminals BP 1  and BP 2  are connected to one terminal of fuse FP. Negative DC terminals BN 1  and BN 2  are connected to one terminal of fuse FN. In the example of converter  1 R in  FIG. 2 , positive DC terminal BP 1  is connected to one terminal of fuse FP 1 , and negative DC terminal BN 1  is connected to one terminal of fuse FN 1 . Positive DC terminal BP 1  corresponds to an embodiment of “first positive DC terminal”, and positive DC terminal BP 2  corresponds to an embodiment of “second positive DC terminal”. Negative DC terminal BN 1  corresponds to an embodiment of “first negative DC terminal”, and negative DC terminal BN 2  corresponds to an embodiment of “second negative DC terminal”. 
     Power converter  10  further includes DC lines  14  and  16 , an AC line  18 , a plurality of semiconductor modules M 1  to M 4 , and a capacitor  12 . 
     DC line  14  is connected between positive DC terminal BP 1  and positive DC terminal BP 2 . DC line  16  is connected between negative DC terminal BN 1  and negative DC terminal BN 2 . AC line  18  is connected between AC terminal AC 1  and AC terminal AC 2 . 
     A plurality of semiconductor modules M 1  to M 4  are connected in parallel with each other between DC line  14  and DC line  16 . Hereinafter, semiconductor modules M 1  to M 4  may be collectively referred to as semiconductor module M. The number of semiconductor modules M is not limited to four and can be changed to any number including one. 
     Semiconductor module M has semiconductor switching elements Q 1  and Q 2 , diodes D 1  and D 2 , a collector terminal C 1 , an emitter terminal E 2 , a collector-emitter terminal C 2 E 1 , and control terminals G 1 , G 2 , E 1 , and E 2 . Each of semiconductor switching elements Q 1  and Q 2  is, for example, an IGBT (Insulated Gate Bipolar Transistor). IGBT Q 1  has the collector connected to collector terminal C 1  and has the emitter connected to the collector of IGBT Q 2 , control terminal E 1 , and collector-emitter terminal C 2 E 1 . IGBT Q 1  has the gate connected to control terminal G 1 . IGBT Q 2  has the emitter connected to emitter terminal E 2  and control terminal E 2  and has the gate connected to control terminal G 2 . Diode D 1  is connected in anti-parallel with IGBT Q 1 , and diode D 2  is connected in anti-parallel with IGBT Q 2 . 
     Semiconductor module M has collector terminal C 1  connected to DC line  14  and emitter terminal E 2  connected to DC line  16 . Semiconductor module M has collector-emitter terminal C 2 E 1  connected to AC line  18 . 
     Capacitor  12  has the positive electrode connected to DC line  14  and the negative electrode connected to DC line  16 . Capacitor  12  has a plurality of capacitor units CD connected in parallel, as described later. 
       FIG. 3  shows a configuration example of inverter  2 U using power converter  10 . The configuration example shown in  FIG. 3  differs from the configuration example shown in  FIG. 2  only in the connection of DC buses PL 1  and NL 1  and the AC line. In the example of inverter  2 U, AC terminal AC 1  is connected to U-phase line UL and outputs U-phase voltage VU. AC terminal AC 1  corresponds to an embodiment of “first AC terminal”. Positive DC terminal BP 2  is connected to one terminal of fuse FP 2 , and negative DC terminal BN 2  is connected to one terminal of fuse FN 2 . 
       FIG. 4  is a diagram schematically showing a connection relation between power converter  10  and control device  9  according to the present embodiment. 
     Referring to  FIG. 4 , control terminals G 1 , G 2 , E 1 , and E 2  of each semiconductor module M are connected to control device  9 . Each semiconductor module M has collector terminal C 1  connected to DC line  14 , emitter terminal E 2  connected to DC line  16 , and collector-emitter terminal C 2 E 1  connected to AC line  18 . 
     A plurality of capacitor units CD that constitute capacitor  12  are connected in parallel between DC line  14  and DC line  16 . The number of capacitor units CD can be changed as desired. 
     Positive DC terminals BP 1  and BP 2  are drawn from DC line  14  to the outside of power converter  10 . Negative DC terminals BN 1  and BN 2  are drawn from DC line  16  to the outside of power converter  10 . AC terminals AC 1  and AC 2  are drawn from AC line  18  to the outside of power converter  10 . 
     As described above, converter  1 R and inverter  2 U can be implemented using power converters  10  having a common configuration by changing the connection of wiring. The commonality of components enhances the productivity of power conversion devices and consequently can reduce the production cost. In addition, the repair and/or replacement of failed components, if any, is facilitated and therefore the cost for maintenance of the power conversion device can be reduced. 
     Configuration Example of Power Conversion Device 
     A configuration example of power converter  10  and a power conversion device (uninterruptible power supply device  100 ) equipped with power converters  10  according to the present embodiment will now be described. 
       FIG. 5  is a front view of uninterruptible power supply device  100  according to the present embodiment.  FIG. 6  is a top view of uninterruptible power supply device  100  according to the present embodiment. In the following description, the right-left direction (or length direction) is X direction, the front-back direction (or width direction) is Z direction, and the top-bottom direction (or thickness direction) is Y direction. 
       FIG. 5  and  FIG. 6  specifically show the portion related to the power conversion device according to the present embodiment. The components of uninterruptible power supply device  100 , including the power conversion device shown in  FIG. 5  and  FIG. 6 , are accommodated in a not-shown board-shaped (rectangular parallelepiped shaped) casing. 
     Referring to  FIG. 5 , uninterruptible power supply device  100  further includes stages  110 ,  120 , and  130 , and a partition plate  140 . Uninterruptible power supply device  100  is formed by stacking stages  110 ,  120 , and  130  provided with power conversion units  21  to  23 , respectively, in the top-bottom direction (Y direction). In the example in  FIG. 5 , power conversion unit  23  is mounted on stage  130  on the bottom layer, power conversion unit  22  is mounted on stage  120  on the middle layer, and power conversion unit  21  is mounted on stage  110  on the top layer.  FIG. 6  shows a plan view of power conversion unit  21  on the top layer. 
     Partition plate  140  has a rectangular flat plate-like shape and is installed upright on the bottom surface of the casing of uninterruptible power supply device  100 . Partition plate  140  has a first surface vertical to the Z direction and a second surface on the opposite side to the first surface. Stages  110 ,  120 , and  130  are fixed to the first surface of partition plate  140 . DC positive bus PL and DC negative bus NL are conductive members having a strip-like shape. The conductive members are arranged to extend in the Y direction on the second surface side of partition plate  140 . Partition plate  140  has through holes  150  and  160 . 
     Each of stages  110 ,  120 , and  130  has a rectangular flat plate-like shape and has a first surface and a second surface on the opposite side to the first surface. Converter  1 R and inverter  2 U are arranged in alignment in the length direction (X direction) on the first surface of stage  110 . DC buses PL 1  and NL 1  and fuses FP 1 , FP 2 , FN 1 , and FN 2  are arranged in a space between converter  1 R and inverter  2 U. 
     Converter  1 S and inverter  2 V are arranged in alignment in the length direction (X direction) on the first surface of stage  120 . DC buses PL 2  and NL 2  and fuses FP 3 , FP 4 , FN 3 , and FN 2  are arranged in a space between converter  1 S and inverter  2 V. 
     Converter  1 T and inverter  2 W are arranged in alignment in the length direction (X direction) on the first surface of stage  130 . DC buses PL 3  and NL 3  and fuses FP 5 , FP 6 , FN 5 , and FN 6  are arranged in a space between converter  1 T and inverter  2 W. 
     One-end portions of DC positive buses PL 1 , PL 2 , and PL 3  are connected to DC positive bus PL through through holes  150  formed in partition plate  140 . One-end portions of DC negative buses NL 1 , NL 2 , and NL 3  are connected to DC negative bus NL through through holes  160  formed in partition plate  140 . 
     As described above, converters  1 R,  1 S, and  1 T and inverters  2 U,  2 V, and  2 W are configured with common power converters  10 .  FIG. 7  is an external perspective view of power converter  10 . 
     Referring to  FIG. 7 , power converter  10  has a plurality of semiconductor modules M 1  to M 4 , a plurality of capacitor units CD, a laminated bus bar  200 , a casing  300 , substrates  310  and  330 , and a cover  320 . 
     Casing  300  has a rectangular parallelepiped shape and its top surface is open. An opening for introducing cooling air into casing  300  is formed on one-side surface in the Z direction of casing  300 . 
     First substrate  310  is attached to the top surface of casing  300 . First substrate  310  has a rectangular flat plate-like shape. First substrate  310  has a first surface facing the bottom surface of casing  300  and a second surface on the opposite side to the first surface. A not-shown heatsink is fixed to the first surface. The heat sink has a base fixed to the first surface and fins protruding from the base. The heatsink is formed of, for example, a metal having a high thermal conductivity, such as aluminum or copper. 
     A plurality of semiconductor modules M 1  to M 4  are arranged in alignment in the length direction (X direction) on the second surface of first substrate  310 . However, the arrangement of a plurality of semiconductor modules M 1  to M 4  is not limited to this. 
     As shown in  FIG. 2  and  FIG. 3 , semiconductor module M has semiconductor switching elements Q 1  and Q 2 , diodes D 1  and D 2 , collector terminal C 1 , emitter terminal E 2 , collector-emitter terminal C 2 E 1 , and control terminals G 1 , G 2 , E 1 , and E 2 . Semiconductor module M has a configuration, for example, in which semiconductor switching elements Q 1  and Q 2  and diodes D 1  and D 2  are mounted on a flat plate-like substrate. Semiconductor switching elements Q 1  and Q 2  and diodes D 1  and D 2  are electrically connected by bonding wires or wiring layers. Semiconductor switching elements Q 1  and Q 2  and diodes D 1  and D 2  are sealed by resin together with the substrate, the bonding wires, the wiring layers, and the like. The resin is formed in a substantially rectangular shape. Collector terminal C 1 , emitter terminal E 2 , and collector-emitter terminal C 2 E 1  are arranged so as to protrude in parallel to each other from the surface of the substantially rectangular-shaped resin. Collector terminal C 1 , emitter terminal E 2 , and collector-emitter terminal C 2 E 1  are connected to laminated bus bar  200 , whereby semiconductor module M is mounted on laminated bus bar  200 . 
     A plurality of capacitor units CD are accommodated in the inside of casing  300 . A plurality of capacitor units CD are arranged in alignment upright on the bottom surface of casing  300 . A plurality of capacitor units CD constitute capacitor  12  shown in  FIG. 2  and  FIG. 3 . Capacitor unit CD has a cylindrical portion and a positive electrode terminal and a negative electrode terminal provided at one end of the cylindrical portion. The positive electrode terminal and the negative electrode terminal are connected to laminated bus bar  200 , whereby capacitor CD is mounted on laminated bus bar  200 . 
     A plurality of semiconductor modules M and a plurality of capacitors CD are electrically connected through laminated bus bar  200 . Laminated bus bar  200  forms DC lines  14  and  16  and AC line  18  (see  FIG. 2  to  FIG. 4 ). 
     Laminated bus bar  200  has a substantially rectangular flat plate-like shape and is arranged to face the bottom surface of casing  300 . Laminated bus bar  200  has a first surface  200 A and a second surface  200 B on the opposite side to first surface  200 A. Second surface  200 B faces the bottom surface of casing  300 . A cover  320  covering a part of first surface  200 A is arranged above first surface  200 A in the thickness direction (Y direction). Second substrate  330  is arranged on cover  320 . The not-shown control device  9  (see  FIG. 1 ) and the like are mounted on second substrate  330 . 
       FIG. 8  is a plan view showing a configuration of laminated bus bar  200 . 
     Referring to  FIG. 8 , laminated bus bar  200  has a flat plate portion  210 , AC terminals AC 1  and AC 2 , positive DC terminals BP 1  and BP 2 , and negative DC terminals BN 1  and BN 2 . 
     Flat plate portion  210  has a length direction (X direction), a width direction (Z direction) orthogonal to the length direction, and a thickness direction (Y direction) orthogonal to the length direction and the width direction. Flat plate portion  210  has a plurality of through holes  211  to  215  passing through in the thickness direction. Through hole  211  (second through hole) is arranged at a position corresponding to collector terminal C 1  of semiconductor module M. Through hole  212  (first through hole) is arranged at a position corresponding to collector-emitter terminal C 2 E 1  of semiconductor module M. Through hole  213  (third through hole) is arranged at a position corresponding to emitter terminal E 2  of semiconductor module M. Through hole  214  (fourth through hole) is arranged at a position corresponding to the positive electrode terminal of capacitor unit CD. Through hole  215  (fifth through hole) is arranged at a position corresponding to the negative electrode terminal of capacitor unit CD. A not-shown connection terminal (for example, bolt) is inserted in each through hole. With this connection terminal, each of collector terminal C 1 , collector-emitter terminal C 2 E 1 , and emitter terminal E 2  of semiconductor module M, and the positive electrode terminal and the negative electrode terminal of capacitor unit CD can be electrically connected at a predetermined position to laminated bus bar  200 . 
       FIG. 9  is an exploded perspective view of flat plate portion  210  of laminated bus bar  200 . Referring to  FIG. 9 , flat plate portion  210  has a first conductive plate  220 AC, a second conductive plate  220 P, a third conductive plate  220 N, and first to fourth insulating plates  215 . First to fourth insulating plates  215  and first to third conductive plates  220 AC,  220 P, and  220 C are alternately stacked to form a stack. Specifically, the stack includes fourth insulating plate  215 , third conductive plate  220 N, third insulating plate  215 , second conductive plate  220 P, second insulating plate  215 , first conductive plate  220 AC, and first insulating plate  215  stacked in this order from below. 
     First AC terminal AC 1  and second AC terminal AC 2  are formed at first conductive plate  220 AC. First conductive plate  220 AC forms AC line  18  (see  FIG. 2  to  FIG. 4 ). 
     First positive DC terminal BP 1  and second positive DC terminal BP 2  are formed at second conductive plate  220 P. Second conductive plate  220 P forms DC line  14  (see  FIG. 2  to  FIG. 4 ). 
     First negative DC terminal BN 1  and second negative DC terminal BN 2  are formed at third conductive plate  220 N. Third conductive plate  220 N forms DC line  16  (see  FIG. 2  to  FIG. 4 ). 
     As shown in  FIG. 8 , in a first end portion  210 A in the length direction (X direction) of flat plate portion  210 , first AC terminal AC 1  protrudes from first conductive plate  220 AC in the length direction. First positive DC terminal BP 1  protrudes from second conductive plate  220 P in the length direction. First negative DC terminal BN 1  protrudes from third conductive plate  220 N in the length direction, Each of first AC terminal AC 1 , first positive DC terminal BP 1 , and first negative DC terminal BN 1  has a rectangular flat plate-like shape and has a connection hole  203  formed by drilling. 
     In a second end portion  210 B in the length direction of flat plate portion  210 , second AC terminal AC 2  protrudes from first conductive plate  220 AC in the length direction. Second positive DC terminal BP 2  protrudes from second conductive plate  220 P in the length direction. Second negative DC terminal BN 2  protrudes from third conductive plate  220 N in the length direction. Each of second AC terminal AC 2 , second positive DC terminal BP 2 , and second negative DC terminal BN 2  has a rectangular flat plate-like shape and has a connection hole  203  formed by drilling. 
     First AC terminal AC 1 , first positive DC terminal BP 1 , and first negative DC terminal BN 1  are arranged in alignment in this order from a third end portion  210 C in the width direction of flat plate portion  210  toward a fourth end portion  210 D on the opposite side to third end portion  210 C. On the other hand, second AC terminal AC 2 , second negative DC terminal BN 2 , and second positive DC terminal BP 2  are arranged in alignment in this order from third end portion  210 C in the width direction of flat plate portion  210  toward fourth end portion  210 D. 
     Furthermore, in the example in  FIG. 8 , first AC terminal AC 1  and second AC terminal AC 2  are arranged at positions facing each other in the length direction with flat plate portion  210  interposed therebetween. First positive DC terminal BP 1  and second negative DC terminal BN 2  are arranged at positions facing each other in the length direction with flat plate portion  210  interposed therebetween. First negative DC terminal BN 1  and second positive DC terminal BP 2  are arranged at positions facing each other in the length direction with flat plate portion  210  interposed therebetween. That is, the order in which positive DC terminal BP and negative DC terminal BN are arranged is opposite between first end portion  210 A and second end portion  210 B of laminated bus bar  200 . 
     In power conversion unit  21  shown in  FIG. 6 , first power converter  10  (converter  1 R) and second power converter  10  (inverter  2 U) are arranged in alignment in the length direction (X direction). Specifically, first end portion  210 A of laminated bus bar  200  of first power converter  10  and second end portion  210 B of laminated bus bar  200  of second power converter  10  face each other in the length direction (X direction), and fourth end portions  210 D of laminated bus bars  200  are arranged in the width direction so as to be aligned in the length direction, In the case of the arrangement as shown in  FIG. 6 , first positive DC terminal BP 1  of first power converter  10  and second negative DC terminal BN 2  of second power converter  10  are arranged to face each other. First negative DC terminal BN 1  of first power converter  10  and second positive DC terminal BP 2  of second power converter  10  are arranged to face each other. 
     As shown in  FIG. 5  and  FIG. 6 , four fuses FP 1 , FP 2 , FN 1 , and FN 2  are arranged between first power converter  10  and second power converter  10 . Each fuse has a substantially rectangular parallelepiped shape. Each fuse has a first terminal and a second terminal. 
     The first terminal of first fuse FP 1  is connected to first positive DC terminal BP 1  of first power converter  10  (converter  1 R) through a connection member  162 . The second terminal of first fuse FP 1  is connected to a first surface of DC positive bus PL 1  having a strip-like shape. 
     The first terminal of second fuse FP 2  is connected to second positive DC terminal BP 2  of second power converter  10  (inverter  2 U) through a connection member  152 . The second terminal of second fuse FP 2  is connected to a second surface on the opposite side to the first surface of DC positive bus PL 1 . 
     The first terminal of third fuse FN 1  is connected to first negative DC terminal BN 1  of first power converter  10  (converter  1 R) through a connection member  164 . The second terminal of third fuse FN 1  is connected to a first surface of DC negative bus NL 1  having a strip-like shape. 
     The first terminal of fourth fuse FN 2  is connected to second negative DC terminal BN 2  of second power converter  10  (inverter  2 U) through a connection member  154 . The second terminal of fourth fuse FN 2  is connected to a second surface on the opposite side to the first surface of DC negative bus NL 1 . 
     Each of connection members  152 ,  154 ,  162 , and  164  is formed by bending the conductive member having a strip-like shape, substantially at right angle. Connection terminals such as bolts can be used for connection between the first terminal of each fuse and the connection member and connection between the second terminal of each fuse and the DC bus. 
     As shown in  FIG. 5 , in a two-dimensional view as viewed from the width direction (Z direction), first fuse FP 1  and second fuse FP 2  are arranged in alignment in the length direction (X direction). Third fuse FN 1  and fourth fuse FN 2  are arranged in alignment in the length direction. Third fuse FN 1  is arranged in alignment with first fuse FP 1  in the thickness direction (Y direction). Fourth fuse FN 2  is arranged in alignment with second fuse FN 2  in the thickness direction. 
     As shown in  FIG. 6 , in a two-dimensional view as viewed from the thickness direction (Y direction), first fuse FP 1  and fourth fuse FN 2  are arranged in alignment in the length direction (X direction). Third fuse FN 1  and second fuse FP 2  are arranged in alignment in the length direction, 
       FIG. 10  is a perspective view of power conversion unit  21  as viewed from a first direction on the second power converter  10  (inverter  2 U) side.  FIG. 11  is a perspective view of power conversion unit  21  as viewed from a second direction on the first power converter  10  (converter  1 R) side. 
     As shown in  FIG. 10  and  FIG. 11 , DC positive bus PL 1  has a first conductive member having a strip-like shape extending in the width direction (Z direction). DC negative bus NL 1  has a second conductive member having a strip-like shape extending in the width direction. The first conductive member and the second conductive member are arranged in alignment in the thickness direction (Y direction). The connection position of first fuse FP 1  to the first conductive member is shifted from the connection position of second fuse FP 2  in the width direction. The connection position of third fuse FN 1  to the second conductive member is shifted from the connection position of fourth fuse FN 2  in the width direction. 
     As shown in  FIG. 5 ,  FIG. 6 ,  FIG. 10 , and  FIG. 11 , four fuses FP 1 , FP 2 , FN 1 , and FN 2  are arranged at positions such that they are not overlap each other in any of the length direction (X direction), the width direction (Z direction), and the thickness direction (Y direction). As shown in  FIG. 5 , therefore, when uninterruptible power supply device  100  is viewed from the width direction, all of four fuses FP 1 , FP 2 , FN 1 , and FN 2  can be seen. This configuration enables the user to easily check whether each fuse is damaged, thereby enhancing the quality of uninterruptible power supply device  100 . 
     When any fuse among four fuses FP 1 , FP 2 , FN 1 , and FN 2  is damaged, the damaged fuse can be easily removed and replaced by a new fuse. The workability in installation and replacement of fuses therefore can be improved. 
     Further, each of DC positive bus PL 1  and DC negative bus NL 1  can be formed with a conductive member having a simple strip-like shape. This configuration facilitates processing and assembly of conductive members that form DC buses PL 1  and NL 1 , thereby reducing the production cost of the power conversion device. 
     As described above, in laminated bus bar  200  according to the present embodiment, even when a plurality of power converters included in the power conversion device are configured with common power converters  10 , the visibility of a plurality of fuses arranged in a space between adjacent two power converters and the workability in attachment thereof are ensured. The commonality of power converters thus can be achieved with a simple configuration. 
     The embodiments disclosed here should be understood as being illustrative rather than being limitative in all respects. The scope of the present invention is shown not in the foregoing description but in the claims, and it is intended that all modifications that come within the meaning and range of equivalence to the claims are embraced here. 
     REFERENCE SIGNS LIST 
       1 R,  1 S,  1 T converter,  2 U,  2 V,  2 W inverter,  5  commercial AC power supply,  6  load,  7  battery,  9  control device,  10  power converter,  12 , C 1  to C 3 , C 11  to C 13  capacitor,  14 ,  16  DC line,  18  AC line,  21  to  23  power conversion unit,  100  uninterruptible power supply device,  110 ,  120 ,  130  stage,  140  partition plate,  152 ,  154 ,  162 ,  164  connection member,  200  laminated bus bar,  203  connection hole,  210  flat plate portion,  211  to  215  through hole,  220 AC first conductive plate,  220 P second conductive plate,  220 N third conductive plate,  225  insulating plate,  300  casing,  310  first substrate,  320  cover,  330  second substrate, AC 1 , AC 2  AC terminal, BP 1 , BP 2  positive DC terminal, BN 1 , BN 2  negative DC terminal, M 1  to M 4  semiconductor module, CD capacitor unit, PL, PL 1  to PL 3  DC positive bus, NL, NL 1  to NL 3  DC negative bus, Q 1 , Q 2  semiconductor switching element, D 1 , D 2  diode.