Patent Publication Number: US-11640871-B2

Title: Transformer and power conversion device

Description:
TECHNICAL FIELD 
     The present disclosure relates to a transformer and a power conversion device including the transformer. 
     BACKGROUND ART 
     An electric railway vehicle is equipped with a power conversion device that converts input DC power or input AC power into desired power and outputs the converted power. For example, an auxiliary power supply device converts power input from an overhead wire and outputs desired power suitable for a load device such as an air conditioner or a lighting device. The power conversion device includes, for example, a transformer disclosed in Patent Literature 1. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Unexamined Japanese Patent Application Kokai Publication No. H08-102423 
     SUMMARY OF INVENTION 
     Technical Problem 
     When the power conversion device performs power conversion, the transformer generates heat. The power conversion device mounted on the electric railway vehicle has a larger capacity than power conversion devices for general industrial use and has a large amount of heat generated by the transformer. Therefore, in order to cool the transformer, for example, the transformer is exposed to ambient air, the power conversion device is provided with a blower to blow air to the transformer. In a case in which cooling of the transformer is insufficient even if the transformer is cooled as described above, cooling capacity is to be enhanced, for example, by using a blower with higher cooling capacity. Alternatively, loss in the transformer is to be reduced and heat generation due to the transformer is to be suppressed by enlarging the core or increasing the number of turns of a coil. As described above, although the cooling capacity of the transformer can be improved and the heat generation can be suppressed, the power conversion device has a further problem in that volumes and weights of the transformer and the blower increase. 
     In order to solve the aforementioned problem, an objective of the present disclosure is to improve cooling capacity while suppressing an increase in the size of a transformer. 
     Solution to Problem 
     In order to achieve the aforementioned objective, a transformer according to the present disclosure includes a base that is a plate-like member and has a first surface and a second surface, a core, coils, coil terminals, and a cooling unit. The core is attached to the first surface of the base. The coils are wound around the core. The coil terminals are each electrically connected to one end of a corresponding coil of the coils, and are disposed on the second surface opposite to the first surface to which the core is attached. The cooling unit is disposed on a side of the core opposite to the base, is thermally connected to the core, and is to release heat transferred from the core. 
     Advantageous Effects of Invention 
     According to the present disclosure, the transformer is provided with the cooling unit that is thermally connected to the core and releases heat transferred from the core, thereby enabling improvement of the cooling capacity while suppressing the increase in the size of the transformer. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view illustrating a transformer according to an embodiment of the present disclosure; 
         FIG.  2    is a cross-sectional view illustrating a power conversion device according to the embodiment; 
         FIG.  3    is a drawing of the transformer according to the embodiment as viewed from a closed section; 
         FIG.  4    is a perspective view illustrating a first modified example of the transformer according to the embodiment; 
         FIG.  5    is a perspective view illustrating a second modified example of the transformer according to the embodiment; 
         FIG.  6    is a perspective view illustrating a third modified example of the transformer according to the embodiment; and 
         FIG.  7    is a drawing illustrating another example of a placement of the transformer according to the embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present disclosure is described below in detail with reference to the drawings. Components that are the same or equivalent are assigned the same reference signs throughout the drawings. 
       FIG.  1    is a perspective view illustrating a transformer according to an embodiment of the present disclosure.  FIG.  2    is a cross-sectional view illustrating a power conversion device according to the embodiment. A power conversion device  30  including a transformer  1  is mounted on an electric railway vehicle.  FIG.  2    is a view illustrating the power conversion device  30  as viewed from above in the vertical direction. The power conversion device  30  is mounted under a floor of the electric railway vehicle, for example, by a hanging clasp that is not illustrated in the drawings. 
     The transformer  1  includes a base  11  that is a plate-like member, a core  12  attached to a first surface  11   a  of the base  11 , coils  13  wound around the core  12 , coil terminals  14  attached to a second surface  11   b  of the base  11 , and a cooling unit  16  that is thermally connected to the core  12  and releases heat transferred from the core  12 . The first surface  11   a  of the base  11  extends in the vertical direction. In the example of  FIG.  1   , the first surface  11   a  of the base  11  is parallel to the vertical direction, and the core  12  included in the transformer  1  is a plurality of cores. The coils  13  are wound around the cores  12 . In the example of  FIG.  1   , the coils  13  are wound around the cores  12  in such a manner that a central axis of each of the coils  13  extends in a direction orthogonal to the first surface  11   a  of the base  11 . The coil terminals  14  are each electrically connected to one end of the corresponding coil  13  of the coils  13 . The coil terminals  14  are disposed on the second surface  11   b  of the base  11  opposite to the first surface  11   a  to which the core  12  is attached. One ends of the coils  13  pass through the interior of an insulating member  17  and the base  11  and are connected to the coil terminals  14  disposed on the second surface  11   b . The cooling unit  16  is disposed on a side of the core  12  opposite to the base  11 . 
     In the example of  FIG.  1   , the transformer  1  includes the cores  12  and further includes a fixing frame  15  to which the cores  12  are fixed. The fixing frame  15  has a thermal conductivity for transferring heat generated by the core  12  to the cooling unit  16  and is made of a material having a strength required for fixing the core  12 , for example, stainless steel. The cooling unit  16  has a fin-like shape and releases heat transferred from the core  12  via the fixing frame  15 . In the example of  FIG.  1   , the cooling unit  16  has fins  16   a  extending in the horizontal direction. The fins  16   a  are attached to the fixing frame  15  at intervals in the vertical direction. The cooling unit  16  is made of a material such as aluminum in accordance with cooling capacity desired for the transformer  1 . 
     The fixing frame  15  is a plate-like member extending in the vertical direction as illustrated in  FIG.  1    and may have a slide portion  18  that (i) extends away from the base  11  at the vertically lower end of the fixing frame  15  and (ii) has an edge located at a position, in the vertical direction, higher than a position of the vertically lower end of the fixing frame  15 . The slide portion  18  forms a slide surface of a vertically lower portion of the transformer  1 , thereby facilitating easy movement of the transformer  1  in the horizontal direction by pushing a handle  19 . In addition to the slide portion  18 , a third surface  11   c  that is a surface on the vertically lower side and orthogonal to the first surface  11   a  and the second surface  11   b  of the base  11  may also form a slide surface of the vertically lower portion of the transformer  1 . Additionally, as in the example of  FIG.  1   , the fixing frame  15  may be provided with a locking member  20 . The locking member  20  has locking holes  20   a . For example, movement of the transformer  1  inside the power conversion device  30  is suppressed by the locking member  20  engaging protrusions of the power conversion device  30  (not illustrated in the drawings) via the locking holes  20   a.    
     The power conversion device  30  includes a housing  31  accommodating the transformer  1  and an electronic circuit  38  illustrated in  FIG.  1   . The housing  31  is divided by a partition  32  into (i) an open section  33  through which an ambient air flow passes and (ii) a closed section  34  through which an ambient air flow does not pass. The partition  32  has an opening  35 . Vents  36  are formed on surfaces of the housing  31  facing the open section  33 . A blower  37  is disposed in the open section  33 . Operation of the blower  37  causes air flowing in from the vent  36  to come into contact with the cooling unit  16 , and the cooling unit  16  releases, into the air, heat transferred from the core  12 . The blower  37  may be omitted and the transformer  1  may be naturally cooled by a wind caused by movement of the railway vehicle on which the power conversion device  30  is mounted. The orientations of the fins  16   a  may be determined in accordance with the flow of air in the open section  33 . The electronic circuit  38  is accommodated in the closed section  34 . The electronic circuit  38  is electrically connected to the coil terminals  14  by a conductor  39  that is, for example a copper bar. The electronic circuit  38  is, for example, a filter circuit disposed on the primary side of the transformer  1 , an inverter circuit disposed on the secondary side of the transformer  1 , or the like. 
     The transformer  1  is accommodated in the housing  31  such that (i) the core  12 , the coil  13 , and the cooling unit  16  are disposed in the open section  33  and (ii) the coil terminals  14  are disposed in the closed section  34 , and the base  11  of the transformer  1  covers the opening  35  formed in the partition  32 . By accommodating the transformer  1  as described above, the core  12  requiring cooling is located in the open section  33 , and the coil terminals  14  requiring insulation protection are located in the closed section  34 . The transformer  1  is inserted into the interior of power conversion device  30  from an inspection port formed in the housing  31  and not illustrated in the drawings. As described above, forming of the slide surface by the slide portion  18  facilitates easy pushing of the transformer  1  into the interior of the power conversion device  30  and improves the maintainability of the power conversion device  30 . As described above, since the position of one end of the slide portion  18  in the vertical direction is higher than the position of the vertically lower end of the fixing frame  15 , when the transformer  1  is pushed into the interior of the power conversion device  30 , the transformer  1  is inhibited from getting caught on the bottom surface of the housing  31 . For example, the transformer  1  is inserted into the interior of the power conversion device  30  from the inspection opening that is formed in the housing  31  located on the lower side in  FIG.  2   , and the first surface  11   a  of the base  11  is pushed until the first surface  11   a  abuts the partition  32 . 
       FIG.  3    is a drawing of the transformer according to the embodiment as viewed from the closed section. The base  11  of the transformer  1  covers the opening  35 , thereby separating the open section  33  and the closed section  34  from each other. That is, an additional member is not needed for separating the open section  33  and the closed section  34  from each other. Additionally, a member is not needed for blocking the entry of dust, water or the like in the open section  33  into the closed section  34 , such as a cable gland. Therefore, reductions in size and weight of the power conversion device  30  and improvement of maintainability of the power conversion device  30  are possible. Any material can be used for making the base  11  as long as the open section  33  and the closed section  34  can be separated from each other. The base  1  may be made of metal material or non-metal material. Packings are attached to all the surfaces of the base  11  that are orthogonal to the first surface  11   a  and the second surface  11   b  and include the third surface  11   c , thereby enabling improvement of enclosure performance of the closed section  34 . Alternatively, a packing is attached around the opening  35 , thereby enabling improvement of the enclosure performance of the closed section  34 . 
       FIG.  4    is a perspective view illustrating a first modified example of the transformer according to the embodiment. A transformer  2  illustrated in  FIG.  4    includes a cooling unit  21  instead of the cooling unit  16  of the transformer  1  illustrated in  FIG.  1   . The cooling unit  21  has a lattice-like shape. Since the surface area of the cooling unit  21  is larger than the surface area of the cooling unit  16  having a fin-like shape, the cooling capacity of the transformer  2  improves. 
       FIG.  5    is a perspective view illustrating a second modified example of the transformer according to the embodiment. A transformer  3  illustrated in  FIG.  5    includes a cooling unit  22  instead of the cooling unit  16  of the transformer  1  illustrated in  FIG.  1   . The cooling unit  22  includes (i) heat pipes  23  in which refrigerant is enclosed and (ii) fins  24  each attached to the heat pipes  23 . 
       FIG.  6    is a perspective view illustrating a third modified example of the transformer according to the embodiment. A transformer  4  illustrated in  FIG.  6    includes one core  25  instead of the cores  12  of the transformer  1  illustrated in  FIG.  1   . The core  25  has (i) a pair of end portions  26  extending in parallel with the first surface  11   a  of the base  11  and (ii) legs  27  connecting the pair of end portions  26 . Additionally, the transformer  4  illustrated in  FIG.  6    has a cooling unit  28  instead of the cooling unit  16  of the transformer  1  illustrated in  FIG.  1   . The cooling unit  28  is directly attached to the core  25  and releases heat transferred from the core  25 . In the example of  FIG.  6   , the cooling unit  28  includes fins  28   a  extending in the horizontal direction. The fins  28   a  are attached to the core  25  at intervals in the vertical direction. The orientations of the fins  28   a  can be determined in accordance with the flow of air in the open section  33 . The shape of the cooling unit  28  is not limited to the fin-like shape and may be a lattice-like shape like the cooling unit  21  of the transformer  2  illustrated in  FIG.  4   . Alternatively, the cooling unit  28  may include the heat pipes  23  and fins  24  like the cooling unit  22  illustrated in  FIG.  5   . 
     As described above, the transformers  1 ,  2  and  3  according to the embodiment respectively include the cooling units  16 ,  21  and  22  each of which is thermally connected to the core  12  and releases heat transferred from the core  12  via the fixing frame  15 , thereby enabling improvement of the cooling capacity while suppressing an increase in the sizes of the transformers  1 ,  2  and  3 . Additionally, the transformer  4  according to the embodiment includes the cooling unit  28  that is directly connected to one core  25  and releases heat transferred from the core  25 , thereby enabling improvement of the cooling capacity while suppressing an increase in the size of the transformer  4 . 
     Embodiments according to the present disclosure are not limited to the above-described embodiment. The orientation in which the transformer  1  is placed is not limited to the above-described example.  FIG.  7    is a drawing illustrating another example of placement of the transformer according to the embodiment. The transformer  1  may be placed such that the first surface  11   a  and the second surface  11   b  of the base  11  are orthogonal to the vertical direction. The same applies to the transformers  2 ,  3  and  4 . The power conversion device  30  including the transformer  1  illustrated in  FIG.  7    includes the open section  33  located in the vertically upper portion and the closed section  34  located in the vertically lower portion. The transformer  1  may be inserted into the interior of the power conversion device  30  from the inspection port formed in the vertically lower surface of the housing  31  of the power conversion device  30 . The shapes of the cores  12  and  25  are not limited to those of the above-described examples. The number of coils  13  is freely selected as two or more. Additionally, the method of winding the coil  13  around the cores  12  and  25  is not limited to the above-mentioned examples. 
     The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the included claims, along with the full range of equivalents to which such claims are entitled. 
     REFERENCE SIGNS LIST 
     
         
           1 ,  2 ,  3 ,  4  Transformer 
           11  Base 
           11   a  First surface 
           11   b  Second surface 
           11   c  Third surface 
           12 ,  25  Core 
           13  Coil 
           14  Coil terminal 
           15  Fixing frame 
           16 ,  21 ,  22 ,  28  Cooling unit 
           16   a ,  24 ,  28   a  Fin 
           17  Insulating member 
           18  Slide portion 
           19  Handle 
           20  Locking member 
           20   a  Locking hole 
           23  Heat pipe 
           26  End portion 
           27  Leg 
           30  Power conversion device 
           31  Housing 
           32  Partition 
           33  Open section 
           34  Closed section 
           35  Opening 
           36  Vent 
           37  Blower 
           38  Electronic circuit 
           39  Conductor