Patent Publication Number: US-2013241327-A1

Title: Motor driving device and vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The priority application number JP2012-057012, Motor Driving Device and Vehicle, Mar. 14, 2012, Akira Soma, Hidenori Hara, Yushi Takatsuka, upon which this patent application is based is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a motor driving device and a vehicle. 
     2. Description of the Background Art 
     A motor driving device including a motor having a high speed drive coil and a low speed drive coil is known in general. Japanese Patent Laying-Open No. 2010-017055 discloses a motor driving device including a motor having a high speed drive coil and a low speed drive coil, a coil switching portion switching the connection states of the two coils of the motor, and an inverter (power converter) connected to the motor. 
     In the conventional motor driving device including the motor, the coil switching portion, and the power converter disclosed in the aforementioned Japanese Patent Laying-Open No. 2010-017055, the motor, the coil switching portion, and the power converter are generally stored in separate case portions and placed separately. 
     SUMMARY OF THE INVENTION 
     A motor driving device according to a first aspect includes a motor including a high speed drive coil and a low speed drive coil, a coil switching portion switching connection states of the high speed drive coil and the low speed drive coil of the motor, arranged in a direction along a rotating shaft of the motor with respect to the motor, a power converter connected to the motor, arranged in a direction intersecting with the rotating shaft with respect to the motor, and a plurality of case portions storing at least the motor, the coil switching portion, and the power converter, while the plurality of case portions are coupled with each other. 
     A vehicle according to a second aspect includes a vehicle body portion and a motor driving portion placed inside the vehicle body portion, while the motor driving portion includes a motor including a high speed drive coil and a low speed drive coil, a coil switching portion switching connection states of the high speed drive coil and the low speed drive coil of the motor, arranged in a direction along a rotating shaft of the motor with respect to the motor, a power converter connected to the motor, arranged in a direction intersecting with the rotating shaft with respect to the motor, and a plurality of case portions storing at least the motor, the coil switching portion, and the power converter, and the plurality of case portions are coupled with each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing the schematic structure of a vehicle according to an embodiment; 
         FIG. 2  is a perspective view showing the overall structure of a motor driving portion according to the embodiment; 
         FIG. 3  is an exploded perspective view of the motor driving portion shown in  FIG. 2 ; 
         FIG. 4  is a perspective view for illustrating a cooling tube provided in a first case portion of the motor driving portion according to the embodiment; 
         FIG. 5  is a perspective view of the motor driving portion shown in  FIG. 2  as viewed along arrow Y 1 ; 
         FIG. 6  is a perspective view showing a coil switching portion mounted on a second case portion of the motor driving portion according to the embodiment; 
         FIG. 7  is a diagram of the coil switching portion shown in  FIG. 6  as viewed along arrow Y 2 ; 
         FIG. 8  is a diagram of the motor driving portion shown in  FIG. 2 , from which the second case portion and the coil switching portion are removed, as viewed along arrow Y 2 ; and 
         FIG. 9  is a diagram for illustrating a connection relation between a motor and an inverter and a connection relation between the motor and the coil switching portion in the first case portion and the second case portion of the motor driving portion according to the embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     An embodiment is now described with reference to the drawings. 
     First, the schematic structure of a vehicle  100  and a motor driving portion  10  according to this embodiment is described with reference to  FIG. 1 . 
     As shown in  FIG. 1 , the vehicle  100  includes a vehicle body portion  101 , the motor driving portion  10  provided inside the vehicle body portion  101 , and a battery portion  20  connected to the motor driving portion  10 . The motor driving portion  10  is an example of the “motor driving device”. 
     The motor driving portion  10  includes an inverter  1 , a smoothing condenser  2 , a motor  3 , a coil switching portion  4 , and a controller  5 . The inverter  1  is an example of the “power converter”. 
     The inverter  1  is configured to convert DC power input from the battery portion  20  into three-phase (U-phase, V-phase, and W-phase) AC power to output the AC power to the motor  3 . The inverter  1  has DC input terminals TP 1  and TN 1  connected to the battery portion  20  and AC output terminals TU 1 , TV 1 , and TW 1  connected to the motor  3 . The DC input terminals TP 1  and TN 1  of the inverter  1  are connected with terminals TP 2  and TN 2  of the smoothing condenser  2 , respectively. This smoothing condenser  2  is provided to smooth the DC power input to the inverter  1  from the battery portion  20 . In other words, the smoothing condenser  2  is configured to reduce pulsation due to the load of voltage output from the battery portion  20 . 
     Furthermore, the inverter  1  includes six switching elements Q 1 , Q 2 , Q 3 , Q 4 , Q 5 , and Q 6  for power conversion. The switching elements Q 1  and Q 2  are configured to perform U-phase power conversion. The switching elements Q 3  and Q 4  are configured to perform V-phase power conversion. The switching elements Q 5  and Q 6  are configured to perform W-phase power conversion. The switching elements Q 1  to Q 6  each are made of a SiC (silicon carbide) semiconductor. 
     The motor  3  is configured to be driven on the basis of three-phase AC power supplied from the inverter  1 . The motor  3  includes a three-phase coil  3   a  for high speed drive and a three-phase coil  3   b  for low speed drive. The coils  3   a  and  3   b  are examples of the “high speed drive coil” and the “low speed drive coil”, respectively. 
     The coils  3   a  and  3   b  are electrically connected in series. Terminals TU 2 , TV 2 , and TW 2  of three phases (U-phase, V-phase, and W-phase) on a first side of the coil  3   a  are connected to the inverter  1 . Terminals TU 3 , TV 3 , and TW 3  of three phases on a second side of the coil  3   a  and a first side of the coil  3   b  are connected to a diode bridge DB 1  of the coil switching portion  4  described later. Terminals TU 4 , TV 4 , and TW 4  on a second side of the coil  3   b  are connected to a diode bridge DB 2  of the coil switching portion  4  described later. 
     The coil switching portion  4  has a function of switching the connection states of the coils  3   a  and  3   b  of the motor  3 . Specifically, the coil switching portion  4  includes a high speed coil switch SW 1  to short the terminals TU 3 , TV 3 , and TW 3  of the motor  3  and a low speed coil switch SW 2  to short the terminals TU 4 , TV 4 , and TW 4  of the motor  3 . The high speed coil switch SW 1  and the low speed coil switch SW 2  are examples of the “switching elements”. The high speed coil switch SW 1  and the low speed coil switch SW 2  each are made of a SiC semiconductor. 
     The coil switching portion  4  includes the diode bridge DB 1  connected to the high speed coil switch SW 1  and the diode bridge DB 2  connected to the low speed coil switch SW 2 . The diode bridge DB 1  has terminals TU 5 , TV 5 , and TW 5  connected to the terminals TU 3 , TV 3 , and TW 3  of the motor  3 , respectively. The diode bridge DB 2  has terminals TU 6 , TV 6 , and TW 6  connected to the terminals TU 4 , TV 4 , and TW 4  of the motor  3 , respectively. 
     The diode bridge DB 1  is constituted by six diodes D 11 , D 12 , D 13 , D 14 , D 15 , and D 16  to rectify three-phase (U-phase, V-phase, and W-phase) alternating current output from the terminals TU 3 , TV 3 , and TW 3  of the motor  3 . The diodes D 11  and D 12  are configured to rectify U-phase alternating current. The diodes D 13  and D 14  are configured to rectify V-phase alternating current. The diodes D 15  and D 16  are configured to rectify W-phase alternating current. 
     The diode bridge DB 2  is constituted by six diodes D 21 , D 22 , D 23 , D 24 , D 25 , and D 26  to rectify three-phase (U-phase, V-phase, and W-phase) alternating current output from the terminals TU 4 , TV 4 , and TW 4  of the motor  3 . The diodes D 21  and D 22  are configured to rectify U-phase alternating current. The diodes D 23  and D 24  are configured to rectify V-phase alternating current. The diodes D 25  and D 26  are configured to rectify W-phase alternating current. 
     The controller  5  is connected to an unshown controller of the entire vehicle  100  provided outside the motor driving portion  10 . The controller  5  is configured to output control signals (an inverter control signal, a high speed coil switching control signal, and a low speed coil switching control signal) to the inverter  1  and the coil switching portion  4 . Thus, the controller  5  controls switching of the switching elements Q 1  to Q 6  of the inverter  1 , and controls switching of the high speed coil switch SW 1  and the low speed coil switch SW 2  of the coil switching portion  4 . Although not shown in  FIG. 1 , the inverter  1 , the coil switching portion  4 , and the controller  5  each include a power supply circuit. 
     Next, the specific structure of the motor driving portion  10  according to this embodiment is described with reference to  FIGS. 2 to 9 . 
     As shown in  FIGS. 2 to 9 , the motor driving portion  10  includes a first case portion  11  storing the inverter  1 , the smoothing condenser  2 , the motor  3 , and the controller  5  and a second case portion  12  storing the coil switching portion  4 . The first case portion  11  and the second case portion  12  are examples of the “case portions”. The first case portion  11  and the second case portion  12  are made of metal (cast metal) such as aluminum. 
     As shown in  FIG. 3 , the first case portion  11  and the second case portion  12  include a portion  11   a  in the form of a circular cylinder and a portion  12   a  in the form of a circular cylinder each extending along the extensional direction (axial direction: direction Y) of a rotating shaft  31  of the motor  3 . The portion  11   a  in the form of a circular cylinder of the first case portion  11  is an example of the “cylindrical portion”. 
     In this embodiment, the first case portion  11  and the second case portion  12  are fastened to each other along the axial direction (direction Y) with screw members  41  to be coupled with each other, as shown in  FIG. 3 . A plurality of (six) screw holes  11   b  engaged with the screw members  41  are provided in the portion  11   a  in the form of a circular cylinder of the first case portion  11  along the rotational direction of the motor  3 . These screw holes  11   b  are formed to extend along arrow Y 2  from the end surface of the first case portion  11  along arrow Y 1 . As shown in  FIGS. 3 ,  6 , and  7 , a plurality of (six) screw receiving holes  12   b  corresponding to the screw holes  11   b  of the first case portion  11  are provided in the portion  12   a  in the form of a circular cylinder of the second case portion  12  along the rotational direction of the motor  3 . These screw receiving holes  12   b  are formed to pass through the portion  12   a  in the form of a circular cylinder of the second case portion in the direction Y. A portion where the first case portion  11  and the second case portion  12  are coupled with each other (portion between the first case portion  11  and the second case portion  12 ) is sealed with an unshown sealing member having a waterproof function. 
     As shown in  FIGS. 3 and 5 , the motor  3  is arranged in a first region R 1  that is a space surrounded by the inner surface of the portion  11   a  in the form of a circular cylinder. The inverter  1  is arranged in a recessed second region R 2  surrounded by a rectangular wall portion  11   c  formed to protrude upward (along arrow Z 1 ) from the outer surface of the portion  11   a  in the form of a circular cylinder. As shown in  FIG. 5 , the first region R 1  is arranged in the central portion of the first case portion  11 . The second region R 2  is arranged in a direction (along arrow Z 1 ) orthogonal to the rotating shaft  31  of the motor  3  with respect to the first region R 1 . Thus, the inverter  1  arranged in the second region R 2  is arranged in the direction (along arrow Z 1 ) orthogonal to the rotating shaft  31  of the motor  3  with respect to the motor  3  arranged in the first region R 1 . 
     As shown in  FIGS. 3 and 5 , the smoothing condenser  2  is arranged adjacent to the inverter  1  in the second region R 2  where the inverter  1  is arranged. As shown in  FIG. 3 , two through-holes  11   d  are provided in a portion along arrow X 1 , of the wall portion  11   c  surrounding the second region R 2  to allow two connecting wires  71  for electrically connecting connecting terminal portions  61  (connecting terminals corresponding to the aforementioned terminals TP 2  and TN 2  shown in  FIG. 1 ) of the smoothing condenser  2  and the battery portion  20  (see  FIG. 1 ) provided outside the motor driving portion  10  to each other to pass through the wall portion  11   c.    
     As shown in  FIGS. 4 and 5 , a single water-cooling-type cooling tube  13  to cool the inverter  1  and the motor  3  is provided inside the portion  11   a  in the form of a circular cylinder of the case portion  11 . In this embodiment, as shown in  FIG. 5 , the cooling tube  13  is arranged to be held between the motor  3  and the inverter  1 . Thus, the inverter  1  and the motor  3  are water-cooled by the same cooling channel (cooling channel constituted by the single cooling tube  13 ). The first case portion  11  and the cooling tube  13  inside the first case portion  11  are formed by sand mold casting, for example. The cooling tube  13  is an example of the “first cooling portion”. 
     As shown in  FIGS. 4 and 5 , the cooling tube  13  is provided to circumferentially surround the motor  3  arranged in the first region R 1  on the inner surface side of the portion  11   a  in the form of a circular cylinder. Specifically, the cooling tube  13  is so configured that a plurality of linear portions  13   a  (see  FIG. 4 ) extending in the axial direction (direction Y) are arranged at substantially equal intervals along the rotational direction of the motor  3  inside the portion  11   a  in the form of a circular cylinder, as shown in  FIG. 5 . As shown in  FIG. 4 , the plurality of linear portions  13   a  extending in the axial direction, of the cooling tube  13  are bent in the form of a U to be connected to each other on both ends thereof in the axial direction. Thus, the cooling tube  13  constitutes a line of the cooling channel from a first end  13   b  protruding from the outer surface of the portion  11   a  in the form of a circular cylinder along arrow X 2  to a second end  13   c  protruding from the outer surface of the portion  11   a  in the form of a circular cylinder along arrow X 2 , in which cooling water flows. 
     As shown in  FIGS. 2 ,  3 ,  6 , and  7 , a portion  12   c  in the form of a circular flat plate extending in directions (a horizontal direction (direction X) and a vertical direction (direction Z)) orthogonal to the rotating shaft  31  of the motor  3  is provided on an end along arrow Y 1 , of the portion  12   a  in the form of a circular cylinder of the second case portion  12 . This portion  12   c  in the form of a flat plate is integrally formed on the portion  12   a  in the form of a circular cylinder. In this embodiment, the coil switching portion  4  is mounted on the surface of the portion  12   c  in the form of a flat plate closer to the first case portion  11  (along arrow Y 2 ) in a state in surface contact with the surface of the portion  12   c  in the form of a flat plate through an unshown thermally-conductive member such as grease having thermal conductivity, as shown in  FIG. 6 . The surface of the portion  12   c  in the form of a flat plate on which the coil switching portion  4  is mounted, closer to the first case portion  11  (along arrow Y 2 ) is hereinafter referred to as a mounting surface  12   d.    
     In this embodiment, an air-cooling-type cooling fin (heat radiation fin)  12   e  to cool the coil switching portion  4  is provided on the outer surface of the second case portion  12  opposite to the mounting surface  12   d  of the portion  12   c  in the form of a flat plate on which the coil switching portion  4  is mounted (along arrow Y 1 ), as shown in  FIGS. 2 ,  3 ,  6 , and  7 . This cooling fin  12   e  is configured by providing a plurality of platelike members  12   f  extending in the vertical direction (direction Z) while being upright in a direction (axial direction (direction Y)) perpendicular to the portion  12   c  in the form of a flat plate at substantially equal intervals in the horizontal direction (direction X). Thus, the plurality of platelike members  12   f  of the cooling fin  12   e  come into contact with outside air, whereby the coil switching portion  4  is air-cooled. Specifically, heat generated from the coil switching portion  4  is transferred to the portion  12   c  in the form of a flat plate through the unshown thermally-conductive member and the mounting surface  12   d , and thereafter radiated to the opposite side (along arrow Y 1 ) of the mounting surface  12   d  of the portion  12   c  in the form of a flat plate through the plurality of platelike members  12   f  of the cooling fin  12   e . The cooling fin  12   e  is an example of the “second cooling portion”. The cooling fin  12   e  is integrally formed on the outer surface of the second case portion  12  opposite to the mounting surface  12   d  of the portion  12   c  in the form of a flat plate (along arrow Y 1 ). 
     In this embodiment, a substantially disk-shaped partition wall  14  extending in the directions (the horizontal direction (direction X) and the vertical direction (direction Z)) orthogonal to the rotating shaft  31  of the motor  3  is arranged between the second case portion  12  and the motor  3  arranged in the first region R 1  of the first case portion  11 , as shown in  FIG. 3 . A bearing  14   a  connected to the rotating shaft  31  is provided on the central portion of this partition wall  14 . As shown in  FIGS. 3 , and  8 , a single hole  14   b  is provided in the vicinity of the central portion of the partition wall  14  in the horizontal direction (direction X) and an upper portion (along arrow Z 1 ) of the partition wall  14  to allow three connecting terminal portions  62  (connecting terminals corresponding to the aforementioned terminals TU 2 , TV 2 , and TW 2  shown in  FIG. 1 ) of the motor  3  to pass through the partition wall  14 . As shown in  FIG. 9 , the three connecting terminal portions  62  of the motor  3  passing through the hole  14   b  of the partition wall  14  are screwed on L-shaped three connecting terminal portions  63 , described later, mounted on the surface of the partition wall  14  opposite to the motor  3  (along arrow Y 1 ). 
     As shown in  FIGS. 3 and 8 , a pair of concaves  14   c  are provided in the vicinity of the central portion of the partition wall  14  in the vertical direction (direction Z) and both ends of the partition wall  14  in the horizontal direction (direction X) to allow six connecting terminal portions  64  and six connecting terminal portions  65  for electrically connecting the motor  3  and the coil switching portion  4  to each other to pass through the partition wall  14 . The connecting terminal portions  64  are connecting terminals corresponding to the aforementioned terminals TU 3 , TV 3 , TW 3 , TU 4 , TV 4 , and TW 4  of the motor  3  shown in  FIG. 1 . The connecting terminal portions  65  are connecting terminals corresponding to the aforementioned terminals TU 5 , TV 5 , TW 5 , TU 6 , TV 6 , and TW 6  of the coil switching portion  4  shown in  FIG. 1 . As shown in  FIG. 9 , the six connecting terminal portions  64  of the motor  3  passing through the concaves  14   c  of the partition wall  14  and the six connecting terminal portions  65  of the coil switching portion  4  passing through the concaves  14   c  of the partition wall  14  are screwed to each other to be electrically connected to each other. As shown in  FIG. 3 , the motor  3  and the coil switching portion  4  are arranged to be opposed to each other on sides provided with the connecting terminal portions  64  and  65 . 
     As shown in  FIGS. 3 ,  8 , and  9 , the three L-shaped three connecting terminal portions  63  are mounted on a portion in the vicinity of the aforementioned hole  14   b , of the surface of the partition wall  14  opposite to the motor  3  (along arrow Y 1 ). Although not shown in  FIGS. 3 ,  8 , and  9 , the three connecting terminal portions  63  each are mounted on the surface of the partition wall  14  closer to the second case portion  12  (along arrow Y 1 ) through an insulating member made of resin or the like. As shown in  FIGS. 8 and 9 , the three connecting terminal portions  63  are screwed on the three connecting terminal portions  62  of the motor  3  and L-shaped three connecting terminal portions  67  screwed on three connecting terminal portions  66  (connecting terminals corresponding to the aforementioned terminals TU 1 , TV 1 , and TW 1  shown in  FIG. 1 ) of the inverter  1 . 
     In this embodiment, a pair of first openings  11   e  having a rectangular shape are provided in portions of the portion  11   a  in the form of a circular cylinder of the first case portion  11  closer to the second case portion  12  (along arrow Y 1 ) on both sides in the horizontal direction (direction X), as shown in  FIGS. 3 and 9 . As shown in  FIG. 9 , the pair of first openings  11   e  are arranged in positions corresponding to portions where the connecting terminal portions  64  of the motor  3  and the connecting terminal portions  65  of the coil switching portion  4  are screwed to each other. Thus, the operation of screwing the connecting terminal portions  64  of the motor  3  and the connecting terminal portions  65  of the coil switching portion  4  to each other can be externally performed through the first openings  11   e  when the first case portion  11  and the second case portion  12  are coupled with each other. As shown in  FIGS. 2 to 4 , the pair of first openings  11   e  are covered with a pair of platelike first lids  15  having shapes (rectangular shapes) corresponding to the first openings  11   e . The first lids  15  are attached to portions of the first case portion  11  corresponding to the first openings  11   e  in an openable/closable manner with an unshown screw member or the like. Portions between the first lids  15  and the first case portion  11  are sealed with unshown sealing members each having a waterproof function. 
     In this embodiment, a second opening  11   f  having a circular shape is provided in a portion of the first case portion  11  corresponding to the first region R 1 , as shown in  FIG. 3 . This second opening  11   f  is covered with the second case portion  12  coupled with the first case portion  11 . As shown in  FIGS. 3 and 5 , a third opening  11   g  having a rectangular shape is provided in a portion of the first case portion  11  corresponding to the second region R 2 . This third opening  11   g  is covered with a platelike second lid  16  having a shape (rectangular shape) corresponding to the third opening  11   g . The second lid  16  is attached to the portion of the first case portion  11  corresponding to the second region R 2  in an openable/closable manner with an unshown screw member or the like. A portion between the second lid  16  and the first case portion  11  is sealed with an unshown sealing member having a waterproof function. 
     As shown in  FIGS. 3 and 9 , a single hole  11   i  is provided in an end along arrow Y 1 , of the bottom surface portion  11   h  of the portion of the first case portion  11  corresponding to the second region R 2  to allow the L-shaped three connecting terminal portions  67  to pass through the bottom surface portion  11   h . As shown in  FIG. 9 , the three connecting terminal portions  67  passing through the hole  11   i  of the first case portion  11  are screwed on the three connecting terminal portions  63  mounted on the partition wall  14  and the three connecting terminal portions  66  of the inverter  1 . Thus, the connecting terminal portions  62  of the motor  3  and the connecting terminal portions  66  of the inverter  1  are electrically connected to each other through the connecting terminal portions  63  and  67 . 
     As shown in  FIGS. 3 and 5 , a third region R 3  where the controller  5  is arranged is provided on the side of the second lid  16  opposite to the first case portion  11  (along arrow Z 1 ). The third region R 3  is a recessed space surrounded by a wall portion  16   a  integrally formed on the second lid  16 . Thus, the second lid  16  serves as a case portion to store the controller  5 . The second lid  16  is an example of the “case portion” or the “third case portion”. 
     As shown in  FIGS. 3 and 5 , a fourth opening  16   b  having a rectangular shape smaller than the third opening  11   g  of the first case portion  11  is provided in a portion of the second lid  16  corresponding to the third region R 3 . This fourth opening  16   b  is covered with a platelike third lid  17  having a shape (rectangular shape) corresponding to the fourth opening  16   b . The third lid  17  is attached to the portion of the second lid  16  corresponding to the third region R 3  in an openable/closable manner with an unshown screw member or the like. A portion between the third lid  17  and the portion of the second lid  16  corresponding to the third region R 3  is sealed with an unshown sealing member having a waterproof function. 
     As shown in  FIG. 3 , a single through-hole  16   c  is provided in a portion along arrow X 1 , of the wall portion  16   a  surrounding the third region R 3  of the second lid  16  to allow a single connecting wire  72  (see  FIG. 2 ) for connecting the controller  5  arranged in the third region R 3  and the unshown controller of the entire vehicle  100  provided outside the motor driving portion  10  to each other to pass through the wall portion  16   a . As shown in  FIGS. 3 and 9 , a hole  16   e  is provided in an end along arrow Y 1 , of the bottom surface portion  16   d  of the portion of the second lid  16  corresponding to the third region R 3  to allow unshown connecting wires, connecting terminal portions, etc. connected to the controller  5  to pass through the bottom surface portion  16   d.    
     According to this embodiment, as hereinabove described, the first case portion  11  and the second case portion  12  storing the motor  3 , the inverter  1 , and the coil switching portion  4  are provided, and coupled with each other. Thus, the first case portion  11  and the second case portion  12  storing the motor  3 , the inverter  1 , and the coil switching portion  4  can be coupled with each other to be integrated. Consequently, formation of a dead space between each case portion storing the motor  3 , the inverter  1 , and the coil switching portion  4  can be suppressed. Furthermore, the coil switching portion  4  is arranged in a direction (along arrow Y 1 ) along the rotating shaft  31  with respect to the motor  3  while the inverter  1  is arranged in the direction (along arrow Z 1 ) orthogonal to the rotating shaft  31  with respect to the motor  3 . Thus, the length of the motor driving portion  10  in the axial direction (direction Y) can be reduced as compared with a case where the motor  3 , the coil switching portion  4 , and the inverter  1  are linearly arranged in the axial direction. Consequently, the vehicle in which a space for the motor driving portion  10  can be saved can be provided. This effect is advantageous particularly in the vehicle  100  in which it is necessary to arrange a large number of members in a limited arrangement space. 
     According to this embodiment, connecting wires to electrically connect the motor  3 , the coil switching portion  4 , and the inverter  1  can be stored in the first case portion  11  and the second case portion  12  coupled with each other. Therefore, no space for placing the connecting wires to electrically connect the motor  3 , the coil switching portion  4 , and the inverter  1  may be provided separately outside the first case portion  11  and the second case portion  12 . Thus, the space for the motor driving portion  10  can be further saved. 
     According to this embodiment, the connecting wires to electrically connect the motor  3 , the coil switching portion  4 , and the inverter  1  are stored in the first case portion  11  and the second case portion  12  coupled with each other. Thus, noise generated from the connecting wires due to switching operations (switching operations of the high speed coil switch SW 1 , the low speed coil switch SW 2 , and the switching elements Q 1  to Q 6 ) of the coil switching portion  4  and the inverter  1  can be shielded by the first case portion  11  and the second case portion  12  coupled with each other. Consequently, the noise generated due to the switching operations of the coil switching portion  4  and the inverter  1  can be inhibited from exerting bad influence on devices placed in the periphery of the motor driving portion  10  inside the vehicle  100 . 
     According to this embodiment, as hereinabove described, the motor  3  and the inverter  1  are stored in the first case portion  11 , and the coil switching portion  4  is stored in the second case portion  12 . Thus, the motor  3 , and the inverter  1  and the coil switching portion  4  are stored in the separate case portions (the first case portion  11  and the second case portion  12 ), so that the coil switching portion  4  can be separated from the motor  3  and the inverter  1  both relatively easily generating heat. Consequently, the coil switching portion  4  can be inhibited from being negatively influenced by the heat from the motor  3  and the inverter  1 , and hence the coil switching portion  4  can be satisfactorily operated. 
     According to this embodiment, as hereinabove described, the water-cooling-type cooling tube  13  to cool the motor  3  and the inverter  1  is provided in the first case portion  11 , and the air-cooling-type cooling fin  12   e  to cool the coil switching portion  4  is provided in the second case portion  12 . Thus, the motor  3  and the inverter  1  both relatively easily generating heat can be cooled by the water-cooling-type cooling tube  13  having high cooling performance. The coil switching portion  4  relatively hardly generating heat can be cooled by the air-cooling-type cooling fin  12   e  having a simple structure. Consequently, the motor  3  and the inverter  1  both relatively easily generating heat can be effectively cooled while simplifying a cooling structure for the coil switching portion  4 . 
     According to this embodiment, as hereinabove described, the cooling fin  12   e  is arranged on the side of the second case portion  12  opposite to the first case portion  11  (along arrow Y 1 ). Thus, the cooling fin  12   e  is arranged in a position easily coming into contact with outside air, and hence the coil switching portion  4  can be further cooled by the cooling fin  12   e.    
     According to this embodiment, as hereinabove described, the cooling fin  12   e  is arranged on the surface of the second case portion  12  opposite to the mounting surface  12   d  of the portion  12   c  in the form of a flat plate (along arrow Y 1 ), and the coil switching portion  4  is mounted on the mounting surface  12   d  of the portion  12   c  in the form of a flat plate in the state in surface contact with the mounting surface  12   d  of the portion  12   c  in the form of a flat plate through the unshown thermally-conductive member such as grease having thermal conductivity. Thus, the heat generated from the coil switching portion  4  and transferred to the portion  12   c  in the form of a flat plate through the thermally-conductive member and the mounting surface  12   d  can be easily radiated to the opposite side (along arrow Y 1 ) of the mounting surface  12   d  of the portion  12   c  in the form of a flat plate through the cooling fin  12   e . Furthermore, the coil switching portion  4  and the mounting surface  12   d  are brought into surface contact with each other through the thermally-conductive member, so that the heat generated from the coil switching portion  4  can be easily transferred to the mounting surface  12   d . Consequently, the cooling effect of the cooling fin  12   e  on the coil switching portion  4  can be further improved. 
     According to this embodiment, as hereinabove described, the coil switching portion  4  is cooled by the cooling fin  12   e  integrally provided on the outer surface of the second case portion  12 . Thus, the number of components can be reduced, dissimilarly to a case where the coil switching portion  4  is cooled by cooling means provided separately from the second case portion  12 . 
     According to this embodiment, as hereinabove described, the single cooling tube  13  is arranged to be held between the motor  3  and the inverter  1 . Thus, the motor  3  and the inverter  1  (two heating elements) can be efficiently cooled by the single cooling tube  13 . 
     According to this embodiment, as hereinabove described, the partition wall  14  extending in the directions (the direction X (horizontal direction) and the direction Z (vertical direction)) orthogonal to the rotating shaft  31  is arranged between the motor  3  stored in the first case portion  11  and the coil switching portion  4  stored in the second case portion  12 . Thus, the partition wall  14  can inhibit the heat generated from the motor  3  from being directly transferred to the coil switching portion  4 . Consequently, the coil switching portion  4  can be further inhibited from being negatively influenced by the heat from the motor  3 , and hence the coil switching portion  4  can be more satisfactorily operated. 
     According to this embodiment, as hereinabove described, the concaves  14   c  are provided in the partition wall  14  to allow the connecting terminal portions  64  and  65  for electrically connecting the motor  3  and the coil switching portion  4  to each other to pass through the partition wall  14 . Thus, the operation of connecting the motor  3  and the coil switching portion  4  to each other can be easily performed through the concaves  14   c  even if the partition wall  14  is arranged between the motor  3  and the coil switching portion  4 . 
     According to this embodiment, as hereinabove described, the first openings  11   e  are provided in the portions (closer to the second case portion  12  (along arrow Y 1 ) on both sides in the horizontal direction (direction X)) of the first case portion  11  corresponding to the connecting terminal portions  64  and  65 , and the openable/closable first lids  15  covering the first openings  11   e  are provided. Thus, the operation of connecting the connecting terminal portions  64  and  65  to each other and maintenance thereof can be easily performed through the first openings  11   e . Furthermore, entry of foreign matter through the first openings  11   e  can be suppressed by covering the first openings  11   e  with the first lids  15 . 
     According to this embodiment, as hereinabove described, the first region R 1  where the motor  3  is arranged is provided in the central portion of the first case portion  11  while the second region R 2  where the inverter  1  is arranged is provided in the direction (along arrow Z 1 ) orthogonal to the rotating shaft  31  with respect to the first region R 1 . Thus, the motor  3  and the inverter  1  are arranged in the first region R 1  and the second region R 2 , respectively, so that the inverter  1  can be easily arranged in the direction (along arrow Z 1 ) orthogonal to the rotating shaft  31  with respect to the motor  3 . 
     According to this embodiment, as hereinabove described, the first case portion  11  includes the portion  11   a  in the form of a circular cylinder extending along the rotating shaft  31  of the motor  3 , and the first region R 1  is arranged on the inner surface side of the portion  11   a  in the form of a circular cylinder while the second region R 2  is arranged on the outer surface side of the portion  11   a  in the form of a circular cylinder. Thus, the first region R 1  can be easily provided in the central portion of the first case portion  11  by utilizing a region on the inner surface side of the portion  11   a  in the form of a circular cylinder, and the second region R 2  can be easily provided in the direction (along arrow Z 1 ) orthogonal to the rotating shaft  31  with respect to the first region R 1  of the first case portion  11  by utilizing a region on the outer surface side of the portion  11   a  in the form of a circular cylinder. 
     According to this embodiment, as hereinabove described, the second opening  11   f  and the third opening  11   g  are provided in the portions of the first case portion  11  corresponding to the first region R 1  and the second region R 2 , respectively. Thus, access to (work on) the motor  3  arranged in the first region R 1  and the inverter  1  arranged in the second region R 2  can be easily facilitated through the second opening  11   f  and the third opening  11   g  in assembling or during maintenance. 
     According to this embodiment, as hereinabove described, the second opening  11   f  is covered with the second case portion  12  in an openable/closable manner while the third opening  11   g  is covered with the second lid  16  in an openable/closable manner. Thus, entry of foreign matter through the second opening  11   f  and the third opening  11   g  can be suppressed by the second case portion  12  and the second lid  16 . 
     According to this embodiment, as hereinabove described, the smoothing condenser  2  smoothing power input to the inverter  1  is arranged in the second region R 2  where the inverter  1  is arranged. Thus, the smoothing condenser  2  and the inverter  1  can be arranged adjacent to each other, and hence the smoothing condenser  2  and the inverter  1  can be easily electrically connected to each other. 
     According to this embodiment, as hereinabove described, the controller  5  controlling the coil switching portion  4  and the inverter  1  is arranged in the third region R 3  of the second lid  16  covering the third opening  11   g  of the first case portion  11 . Thus, the number of components can be reduced, dissimilarly to a case where a dedicated case portion for storing the controller  5  is provided separately from the second lid  16 . 
     According to this embodiment, as hereinabove described, the fourth opening  16   b  is provided in the portion of the second lid  16  corresponding to the third region R 3  where the controller  5  is arranged, and the openable/closable third lid  17  covering the fourth opening  16   b  is provided. Thus, access to (work on) the controller  5  arranged in the third region R 3  of the second lid  16  can be easily facilitated through the fourth opening  16   b  in assembling or during maintenance. Furthermore, entry of foreign matter through the fourth opening  16   b  can be suppressed by the third lid  17 . 
     According to this embodiment, the high speed coil switch SW 1  and the low speed coil switch SW 2  of the coil switching portion  4  and the switching elements Q 1  to Q 6  of the inverter  1  each are made of the SiC semiconductor. Thus, the switching elements Q 1  to Q 6 , the high speed coil switch SW 1 , and the low speed coil switch SW 2  each are made of the SiC semiconductor having excellent heat resistance, so that the switching elements Q 1  to Q 6 , the high speed coil switch SW 1 , and the low speed coil switch SW 2  can be satisfactorily operated even if the inverter  1  and the coil switching portion  4  are arranged in the vicinity of a heating element (motor  3 , for example). 
     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof. 
     For example, in the aforementioned embodiment, the motor driving portion (motor driving device) is loaded in the vehicle. Nevertheless, the motor driving portion (motor driving device) may alternatively be loaded in a ship or the like other than the vehicle. 
     In the aforementioned embodiment, the motor and the inverter are stored in the single case portion (first case portion). Nevertheless, the motor and the inverter may alternatively be stored in separate case portions. 
     In the aforementioned embodiment, the motor and the inverter are water-cooled while the coil switching portion is air-cooled. Nevertheless, the motor and the inverter may alternatively be air-cooled, or the coil switching portion may alternatively be water-cooled. Furthermore, the motor, the inverter, and the coil switching portion may alternatively be cooled by cooling elements. 
     In the aforementioned embodiment, the coil switching portion is cooled by the cooling fin integrally provided on the second case portion, as an example of a case where the coil switching portion is air-cooled. Nevertheless, the coil switching portion may alternatively be cooled by a cooling fan provided separately from the second case portion. 
     In the aforementioned embodiment, the motor and the inverter are cooled by the same cooling channel (single cooling tube), as an example of a case where the motor and the inverter are water-cooled. Nevertheless, the motor and the inverter may alternatively be cooled by separate cooling tubes. 
     In the aforementioned embodiment, the concaves are provided in the partition wall arranged between the motor and the coil switching portion to allow the connecting terminal portions for electrically connecting the motor and the coil switching portion to each other to pass through the partition wall. Nevertheless, not the concaves but holes may alternatively be provided in the partition wall arranged between the motor and the coil switching portion. 
     In the aforementioned embodiment, the first openings employed to perform the operation of connecting the connecting terminal portions of the motor and the connecting terminal portions of the coil switching portion to each other are provided in the first case portion. Nevertheless, the first openings may alternatively be provided in the second case portion or in both the first case portion and the second case portion. 
     In the aforementioned embodiment, the motor and the inverter are arranged in the two regions (the first region and the second region) provided separately from each other on the inner surface side and the outer surface side of the portion in the form of a circular cylinder, respectively. Nevertheless, the motor and the inverter may alternatively be arranged in a single region formed inside a single case portion. 
     In the aforementioned embodiment, the first case portion includes the portion in the form of a circular cylinder, and the motor is arranged on the inner surface side of the portion in the form of a circular cylinder while the inverter is arranged on the outer surface side of the portion in the form of a circular cylinder. Nevertheless, the first case portion may alternatively include a portion in the form of a rectangular cylinder, and the motor may alternatively be arranged on the inner surface side of the portion in the form of a rectangular cylinder while the inverter may alternatively be arranged on the outer surface side of the portion in the form of a rectangular cylinder. 
     In the aforementioned embodiment, the smoothing condenser is arranged in the second region where the inverter is arranged. Nevertheless, the inverter and the smoothing condenser may alternatively be arranged in separate regions. 
     In the aforementioned embodiment, the case portion (third case portion) to store the controller is integrally provided on the second lid. Nevertheless, the case portion (third case portion) to store the controller may alternatively be provided separately from the second lid. 
     In the aforementioned embodiment, the switching elements of the inverter and the high speed coil switch and the low speed coil switch of the coil switching portion each are made of the SiC semiconductor. Nevertheless, the switching elements of the inverter and the high speed coil switch and the low speed coil switch of the coil switching portion each may alternatively be made of a Si semiconductor, for example, other than the SiC semiconductor, or constituted by switching elements other than the switching elements each containing a semiconductor. 
     In the aforementioned embodiment, the first case portion and the second case portion are fastened to each other with the screw members to be coupled with each other. Nevertheless, the first case portion and the second case portion may alternatively be fastened to each other with fastening members other than the screw members, such as caulking members to be coupled with each other, or may alternatively be bonded to each other with an adhesive, for example, without the fastening members to be coupled with each other.