Abstract:
An electric power conversion apparatus comprises: three conversion units; a backup conversion unit that can be substituted for any one of the conversion units; and a backup terminal conductor unit. The conversion units, which are mounted on a converter board disposed in a case, can convert a DC current to a three-phase AC current having U-, V- and W-phases. If any one of the conversion units goes out of order, the backup terminal conductor unit can then electrically connect the auxiliary conversion unit, in substitution for the conversion unit having gone out of order, to a three-phase AC input/output unit.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part (CIP) application based upon the International Application PCT/JP2009/004672, the International Filing Date of which is Sep. 17, 2009, the entire content of which is incorporated herein by reference. 
     
    
     BACKGROUND ART 
       [0002]    The present invention relates to an electric power conversion apparatus which allows short-time recovery from a partial failure. 
         [0003]    Some electric power conversion apparatuses are used to convert a three-phase alternating current power source into a direct current power source to drive electric motors etc. On the other hand, there are other electric power conversion apparatuses which convert a direct current power source into a three-phase alternating current power source and supply the alternating current power source to an electric power system etc. Among known examples of such electric power conversion apparatuses is one disclosed in Japanese Patent Application Laid-Open Publications No. 2002-354840, the entire content of which is incorporated herein by reference. 
         [0004]    An electric power conversion apparatus typically includes a U-phase conversion unit, a V-phase conversion unit, and a W-phase conversion unit which correspond to a three-phase alternating current. The U-phase conversion unit has the function of converting a direct current into a current component corresponding to a current component of a three-phase alternating current corresponding to a U phase, and the function of converting a U-phase current into a direct current. The V-phase conversion unit and the W-phase conversion unit each have similar functions to those of the U-phase conversion unit. 
         [0005]    These conversion units are arranged inside a control panel or the like. The conversion units each may have leading parts or the like that are intended for easy insertion and extraction into/from the control panel. Such a configuration facilitates a recovery operation since a conversion unit corresponding to one phase, if failed, can be easily replaced with a replacement conversion unit. Wiring in the vicinity of the leading parts and the like is often complicated and high in cost. Complicated wiring can sometimes lower energization efficiency. 
         [0006]    A U-phase conversion unit, a V-phase conversion unit, and a W-phase conversion unit are sometimes directly attached to a substrate that is arranged in a casing, for example. Such a configuration allows more compact arrangement of the conversion units. The absence of leading parts and the like can accordingly simplify the wiring for lower manufacturing costs. 
         [0007]    If the conversion units are configured to be directly attached to a substrate or the like, it may take a long time to replace a failed conversion unit. Electric power conversion apparatuses are often used to drive plant and other equipment such as electric motors, and can rarely be stopped for a long time. A failure recovery operation therefore needs to be performed in a short time. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention has been achieved in order to solve the foregoing problem, and it is an object thereof to restore a failed electric power conversion apparatus in a short time. 
         [0009]    In order to achieve the object described above, there is presented an electric power conversion apparatus comprising: a casing; a converter substrate that is arranged in the casing; a first phase conversion unit that is attached to the converter substrate and is configured to be capable of converting a direct current into a first phase current component of a three-phase alternating current; a second phase conversion unit that is attached to the converter substrate and is configured to be capable of converting the direct current into a second phase current component of the three-phase alternating current; a third phase conversion unit that is attached to the converter substrate and is configured to be capable of converting the direct current into a third phase current component of the three-phase alternating current; a backup phase conversion unit that is configured to be capable of replacing each of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit; a three-phase alternating current unit that is electrically connected to each of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit, and is capable of outputting a three-phase alternating current; a direct current unit that is electrically connected to each of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit, and is capable of inputting a direct current; and a backup terminal conductor unit that is arranged at a distance from each of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit, is electrically connected to the backup phase conversion unit, and is configured to be capable of electrically connecting the backup phase conversion unit to the three-phase alternating current unit instead of any one of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit when the one fails. 
         [0010]    There is also presented an electric power conversion apparatus comprising: a casing; a converter substrate that is arranged in the casing; a first phase conversion unit that is attached to the converter substrate and is configured to be capable of converting a first phase current component of a three-phase alternating current into a direct current; a second phase conversion unit that is attached to the converter substrate and is configured to be capable of converting a second phase current component of the three-phase alternating current into a direct current; a third phase conversion unit that is attached to the converter substrate and is configured to be capable of converting a third phase current component of the three-phase alternating current into a direct current; a backup phase conversion unit that is configured to be capable of replacing each of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit; a three-phase alternating current unit that is electrically connected to each of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit, and is capable of inputting a three-phase alternating current; a direct current unit that is electrically connected to each of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit, and is capable of outputting a direct current; and a backup terminal conductor unit that is arranged at a distance from each of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit, is electrically connected to the backup phase conversion unit, and is configured to be capable of electrically connecting the backup phase conversion unit to the three-phase alternating current unit instead of any one of the first phase conversion unit, the second phase conversion unit, and the third phase conversion unit when the one fails. 
         [0011]    According to the present invention, it is possible to restore a failed electric power conversion apparatus in a short time. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The above and other features and advantages of the present invention will become apparent from the discussion hereinbelow of specific, illustrative embodiments thereof presented in conjunction with the accompanying drawings, in which: 
           [0013]      FIG. 1  is a block diagram showing the configuration of an electric power conversion apparatus according to an embodiment of the present invention; and 
           [0014]      FIG. 2  is a block diagram showing a state of recovery when a V-phase conversion unit of the electric power conversion apparatus of  FIG. 1  is failed. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    An embodiment of the electric power conversion apparatus according to the present invention will be described below with reference to  FIGS. 1 to 2 .  FIG. 1  is a block diagram showing the configuration of an electric power conversion apparatus according to the present embodiment.  FIG. 2  is a block diagram showing a state of recovery when a V-phase conversion unit  22  of the electric power conversion apparatus of  FIG. 1  is failed. 
         [0016]    Initially, the configuration of the electric power conversion apparatus according to the present embodiment will be described. 
         [0017]    As shown in  FIG. 1 , the electric power conversion apparatus according to the present embodiment includes: a casing  10 ; a converter substrate  12  which is arranged in the casing  10 ; a three-phase alternating current input/output unit  60 ; a direct current input/output unit  70 ; and three conversion units that are attached to the converter substrate  12  and correspond to a three-phase alternating current. The three conversion units are a U-phase conversion unit  21 , a V-phase conversion unit  22 , and a W-phase conversion unit  23 . 
         [0018]    The electric power conversion apparatus further includes: a control substrate  80  which controls each of the conversion units  21 ,  22 , and  23 ; a backup conversion unit  25  which is configured to be capable of replacing each of the conversion units  21 ,  22 , and  23 ; and a backup terminal conductor unit  50  which is electrically and mechanically connected to the backup conversion unit  25 . 
         [0019]    An example of the converter substrate  12  is a rectangular plate, which is erected and fixed inside the casing  10 . The foregoing four conversion units are vertically arranged at intervals from each other and attached to the converter substrate  12  along the vertical direction. 
         [0020]    The U-phase conversion unit  21  has the function of converting a direct current into a current component corresponding to a current component of a three-phase alternating current corresponding to a U phase, and the function of converting a U-phase current into a direct current. The V-phase conversion unit  22  has the function of converting a direct current into a current component corresponding to a V phase, and the function of converting a V-phase current into a direct current. Similarly, the W-phase conversion unit  23  has the function of converting a direct current into a current component corresponding to a W phase, and the function of converting a W-phase current into a direct current. 
         [0021]    Description will be omitted of the detailed configuration of each of the U-phase conversion unit  21 , the V-phase conversion unit  22 , and the W-phase conversion unit  23 , which are constituted by mounting electric parts such as a thyristor on a horizontally-long rectangular substrate. In this example, the conversion units  21 ,  22 , and  23  are attached to the converter substrate  12  with their longitudinal direction horizontal. 
         [0022]    The U-phase conversion unit  21  includes a U-phase gate unit  31   b.  The control substrate  80  and the U-phase gate unit  31   b  are connected through U-phase control signal wiring  81  so as to be capable of communication with each other. Similarly, the V-phase conversion unit  22  and the W-phase conversion unit  23  include a V-phase gate unit  32   b  and a W-phase gate unit  33   b,  respectively. The V-phage gate unit  32   b  and the W-phase gate unit  33   b  are connected with the control substrate  80  through V-phase control signal wiring  82  and W-phase control signal wiring  83 , respectively, so as to be capable of communication with each other. 
         [0023]    The conversion units  21 ,  22 , and  23  have a U-phase terminal  31   a,  a V-phase terminal  32   a,  and a W-phase terminal  33   a,  respectively, to which a U-phase cable  41 , a V-phase cable  42 , and a W-phase cable  43  to be described later can be electrically and mechanically connected, respectively. 
         [0024]    The control substrate  80  is configured so that it can transmit control signals such as an ON/OFF command to each of the U-phase conversion unit  21 , the V-phase conversion unit  22 , and the W-phase conversion unit  23  through the U-phase gate unit  31   b,  the V-phase gate unit  32   b,  and the W-phase gate unit  33   b,  respectively. 
         [0025]    The three-phase alternating current input/output unit  60  is arranged inside the casing  10  and outside the converter substrate  12 , and is configured to be capable of connection with outside the casing  10 . 
         [0026]    The U-phase terminal  31   a  of the U-phase conversion unit  21  and the three-phase alternating current input/output unit  60  are electrically and mechanically connected to each other by the U-phase cable  41 . Here, an end of the U-phase cable  41  on the conversion unit side and the U-phase terminal  31   a  are electrically and mechanically connected to each other in a detachable manner. The other end of the U-phase cable  41 , i.e., the end on the side of the three-phase alternating current input/output unit  60  is electrically connected and attached to the three-phase alternating current input/output unit  60 . 
         [0027]    Like the U-phase conversion unit  21 , the V-phase conversion unit  22  and the W-phase conversion unit  23  are electrically connected with the three-phase alternating current input/output unit  60  by the V-phase cable  42  and the W-phase cable  43 , respectively. Here, the V-phase conversion unit  22  and the W-phase conversion unit  23  are connected to the V-phase cable  42  and the W-phase cable  43  in a detachable manner, respectively. 
         [0028]    The lengths of the U-phase cable  41 , the V-phase cable  42 , and the W-phase cable  43  are each determined to be optimum when assembling the electric power conversion apparatus. 
         [0029]    The direct current input/output unit  70  includes a P-side input/output unit  72  and an N-side input/output unit  73 . The P-side and N-side input/output units  72  and  73  both are arranged inside the casing  10  and outside the converter substrate  12 , and are configured to be capable of connection with outside the casing  10 . In the example of  FIG. 1 , the P-side and N-side both are arranged to the bottom. 
         [0030]    The P-side input/output unit  72  is connected to the converter substrate  12 , and is electrically connected to each of the U-phase conversion unit  21 , the V-phase conversion unit  22 , and the W-phase conversion unit  23  by wiring formed on the converter substrate  12  through fuses  75  or the like. Similarly, the N-side input/output unit  73  is connected to the converter substrate  12 , and is electrically connected to each of the U-phase conversion unit  21 , the V-phase conversion unit  22 , and the W-phase conversion unit  23  by wiring formed on the converter substrate  12  through fuses  75  or the like. 
         [0031]    Although omitted in  FIG. 1 , the P-side input/output unit  72  and the N-side input/output unit  73  are also configured to be capable of electrical connection with the backup conversion unit  25 . When the U-phase conversion unit  21 , the V-phase conversion unit  22 , and the W-phase conversion unit  23  are in a normal condition, fuses  75  or the like are detached so that the backup conversion unit  25  is electrically disconnected from both the P-side input/output unit  72  and the N-side input/output unit  73 . To electrically connect the backup conversion unit  25  to both the P-side input/output unit  72  and the N-side input/output unit  73 , fuses  75  or the like are attached to allow energization. 
         [0032]    When the electric power conversion apparatus is used to convert a three-phase alternating current power source into a direct current power source, a three-phase alternating current power supply unit (not shown) is connected to the three-phase alternating current input/output unit  60 , whereby an alternating current is transmitted from the three-phase alternating current input/output unit  60  to each of the U-phase conversion unit  21 , the V-phase conversion unit  22 , and the W-phase conversion unit  23 . The conversion units  21 ,  22 , and  23  each convert the alternating current into a direct current, which is output from the direct current input/output unit  70  as a direct current power source. This direct current power source is used, for example, to drive an electric motor (not shown) or the like which is installed in a plant. 
         [0033]    Now, when the electric power conversion apparatus is used to convert a direct current power source into a three-phase alternating current power source, a direct current power supply unit (not shown) is connected to the direct current input/output unit  70 . The direct current transmitted from the direct current input/output unit  70  is branched by wiring or the like formed on the converter substrate  12 , and transmitted to each of the U-phase conversion unit  21 , the V-phase conversion unit  22 , and the W-phase conversion unit  23 . The direct currents transmitted to the conversion units  21 ,  22 , and  23  are converted into alternating currents by the respective conversion units  21 ,  22 , and  23 , transmitted to the three-phase alternating current input/output unit  60 , and output as a three-phase alternating current power source. The three-phase alternating current power source is supplied to a power system (not shown) or the like. 
         [0034]    As mentioned above, the backup conversion unit  25  is configured to be capable of replacing each of the conversion units  21 ,  22 , and  23 . More specifically, when any one of the U-phase conversion unit  21 , the V-phase conversion unit  22 , and the W-phase conversion unit  23  fails, the backup conversion unit  25  can replace the failed conversion unit. 
         [0035]    Like the U-phase conversion unit  21  etc., the backup conversion unit  25  includes a backup phase gate unit  35   b.  The backup phase gate unit  35   b  is configured to be capable of mutual communication with the control substrate  80 . The backup conversion unit  25  also includes a backup phase terminal  35   a  to which a backup conversion unit cable  45  to be described later can be electrically and mechanically connected. The backup conversion unit cable  45  is constantly connected to the backup phase terminal  35   a.    
         [0036]    The backup terminal conductor unit  50  is attached to the converter substrate  12  and arranged at a distance from each of the U-phase conversion unit  21 , the V-phase conversion unit  22 , the W-phase conversion unit  23 , and the backup conversion unit  25 . 
         [0037]    The backup terminal conductor unit  50  is a long plate-like member that is made of a conductor such as a copper alloy and extends in the vertical direction. The long plate-like conductor has four terminals, including a U-phase backup terminal  51 , a V-phase backup terminal  52 , a W-phase backup terminal  53 , and a constant connection terminal  55 . 
         [0038]    The U-phase backup terminal  51  is configured so that the conversion unit-side end of the U-phase cable  41  can be electrically and mechanically connected. The V-phase backup terminal  52  and the W-phase backup terminal  53  are configured so that the conversion unit-side ends of the V-phase cable  42  and the W-phase cable  43  can be electrically and mechanically connected, respectively. When the conversion units  21 ,  22 , and  23  are in a normal condition, none of the cables are connected to the U-phase backup terminal  51 , the V-phase backup terminal  52 , or the V-phase backup terminal  53 . 
         [0039]    The U-phase conversion unit  21 , the V-phase conversion unit  22 , the W-phase conversion unit  23 , and the backup conversion unit  25  are vertically arranged at intervals from each other along the longitudinal direction of the backup terminal conductor unit  50 . The U-phase backup terminal  51  is located within the reach of the conversion unit-side end of the U-phase cable  41  which is connected to the U-phase terminal  31   a  formed on the U-phase conversion unit  21 . This eliminates the need to extend the U-phase cable  41  when switching connection of the U-phase cable  41  from the U-phase terminal  31  a to the U-phase backup terminal  51 . Similarly, the V-phase backup terminal  52  and the W-phase backup terminal  53  are located within the reach of the conversion unit-side ends of the V-phase cable  42  and the W-phase cable  43 , respectively. 
         [0040]    The constant connection terminal  55  is electrically and mechanically connected to the background conversion unit  25  constantly by the backup conversion unit cable  45 . 
         [0041]    Next, the operation of the present embodiment will be described for a case where the V-phase conversion unit  22  fails. 
         [0042]    When the V-phase conversion unit  22  failed, information on the failure is transmitted to a management center (not shown) or the like. Receiving the information, the management center or the like sends a maintenance operator to the installation site of the electric power conversion apparatus that includes the failed unit. 
         [0043]    A procedure for the recovery of the V-phase conversion unit  22  will be described below. 
         [0044]    Initially, the maintenance operator checks for the absence of current supply. Then, as shown in  FIG. 2 , the maintenance operator detaches the fuse  75  that is interposed between the V-phase conversion unit  22  and the P-side input/output unit  72 . 
         [0045]    Next, the maintenance operator detaches the V-phase cable  42  from the V-phase terminal  32   a,  and the maintenance operator connects the V-phase cable  42  to the V-phase backup terminal  52  which is formed on the backup terminal conductor unit  50 . Subsequently, the maintenance operator attaches fuses  75  or the like so that both the P-side input/output unit  72  and the N-side input/output unit  73  are electrically connected with the backup conversion unit  25 . 
         [0046]    Next, the maintenance operator disconnects the communication of the V-phase control signal wiring  82  which is connected to the V-phase gate unit  32   b  so as to be capable of communication. Then, the maintenance operator establishes connection between the control substrate  80  and the backup conversion unit  25  by using backup control signal wiring  85 . 
         [0047]    By the foregoing procedure, the recovery operation in the event of a failure of the V-phase conversion unit  22  is completed. The conversion units other than the V-phase conversion unit  22 , if failed, can be recovered by a similar procedure. 
         [0048]    As can be seen from the foregoing procedure, according to the present embodiment, quick recovery is possible without complicated wiring operations when any one of the U-phase conversion unit  21 , the V-phase conversion unit  22 , and the W-phase conversion unit  23  fails. 
         [0049]    The present embodiment is applicable both when converting a three-phase alternating current power source into a direct current power source and when converting a direct current power source into a three-phase alternating current power source. 
         [0050]    The description of the present embodiment has been given for illustrative purposes in order to describe the present invention, and is by no means to limit the inventions set forth in the claims. The configuration of the components of the present invention is not limited to the foregoing embodiment, and various modifications may be made within the technical scope set forth in the claims. 
         [0051]    For example, while the backup terminal conductor unit  50  of the present embodiment includes the backup terminals  51 ,  52 , and  53  which are dedicated to the respective phases, such a configuration is not restrictive. Since the V-phase cable  42  can be electrically and mechanically connected to the U-phase backup terminal  51 , the U-phase backup terminal  51  may be shared between the U-phase and V-phase.