Patent Publication Number: US-2013241458-A1

Title: Motor driving device and vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The priority application number JP2012-057086, 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, a power converter connected to the motor, and a single first case portion storing at least the motor, the coil switching portion, and the power converter. 
     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, a power converter connected to the motor, and a single first case portion storing at least the motor, the coil switching portion, and the power converter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing the schematic structure of a vehicle and a motor driving portion according to a first embodiment; 
         FIG. 2  is a perspective view showing the overall structure of the motor driving portion according to the first 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 case portion of the motor driving portion shown in  FIG. 2 ; 
         FIG. 5  is a perspective view of the motor driving portion shown in  FIG. 2  as viewed along arrow Y 2 ; 
         FIG. 6  is a diagram of the motor driving portion shown in  FIG. 5 , from which a first lid is removed; 
         FIG. 7  is a partial sectional view for illustrating a connection relation between a motor and an inverter of the motor driving portion shown in  FIG. 2 ; 
         FIG. 8  is a perspective view showing the overall structure of a motor driving portion according to a second embodiment; 
         FIG. 9  is an exploded perspective view of the motor driving portion shown in  FIG. 8 ; 
         FIG. 10  is a perspective view of the motor driving portion shown in  FIG. 8  as viewed along arrow Y 2 ; 
         FIG. 11  is a diagram of the motor driving portion shown in  FIG. 10 , from which a first lid is removed; 
         FIG. 12  is a perspective view showing the overall structure of a motor driving portion according to a third embodiment; 
         FIG. 13  is an exploded perspective view of the motor driving portion shown in  FIG. 12 ; 
         FIG. 14  is a perspective view of the motor driving portion shown in  FIG. 12  as viewed along arrow Y 2 ; 
         FIG. 15  is a diagram of the motor driving portion shown in  FIG. 14 , from which a first lid is removed; 
         FIG. 16  is a perspective view showing the overall structure of a motor driving portion according to a fourth embodiment; 
         FIG. 17  is an exploded perspective view of the motor driving portion shown in  FIG. 16 ; 
         FIG. 18  is a perspective view of the motor driving portion shown in  FIG. 16  as viewed along arrow Y 2 ; and 
         FIG. 19  is a diagram of the motor driving portion shown in  FIG. 18 , from which a first lid is removed. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiments are now described with reference to the drawings. 
     First Embodiment 
     First, the schematic structure of a vehicle  100  and a motor driving portion  10  according to a first 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 switching portion  4   a  having 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 switching portion  4   b  having 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 high speed coil switching portion  4   a  includes the diode bridge DB 1  having 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 low speed coil switching portion  4   b  includes the diode bridge DB 2  having 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 the first embodiment is described with reference to  FIGS. 2 to 7 . In this first embodiment, the coil switching portion  4  is constituted by a single module in which the high speed coil switching portion  4   a  and the low speed coil switching portion  4   b  (see  FIG. 1 ) are integrated. 
     As shown in  FIGS. 2 to 7 , the inverter  1 , the smoothing condenser  2 , the motor  3 , and the coil switching portion  4  of the motor driving portion  10  are stored in a single case portion  11  made of metal (cast metal) such as aluminum. This case portion  11  also stores connecting terminal portions  61 ,  62 ,  63 ,  64 ,  65 , and  66  (described later in detail) to electrically connect the motor  3  with the inverter  1  and the coil switching portion  4 . The case portion  11  is an example of the “first case portion”. 
     As shown in  FIG. 3 , the case portion  11  includes a portion  11   a  in the form of a circular cylinder extending along the extensional direction (axial direction: direction Y) of a rotating shaft  31  (see  FIG. 3 ) of the motor  3 . The portion  11   a  in the form of a circular cylinder is an example of the “cylindrical portion”. In the first embodiment, the motor  3  is arranged in a first region R 1  (space surrounded by the inner surface of the portion  11   a  in the form of a circular cylinder) on the inner surface side of the portion  11   a  in the form of a circular cylinder, as shown in  FIGS. 3 and 5 . 
     Furthermore, the coil switching portion  4  and the inverter  1  are arranged in a second region R 2  and a third region R 3 , respectively, on the outer surface side of the portion  11   a  in the form of a circular cylinder, as shown in  FIGS. 3 and 5 . The second region R 2  is a recessed space surrounded by a rectangular wall portion  11   b  formed to protrude laterally (along arrow X 1 ) from the outer surface of the portion  11   a  in the form of a circular cylinder. The third region R 3  is a recessed space 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. 
     The smoothing condenser  2  is arranged adjacent to the inverter  1  in the third region R 3  where the inverter  1  is arranged, as shown in  FIGS. 3 and 5 . 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 third region R 3  to allow two connecting wires  71  (see  FIG. 2 ) for electrically connecting connecting terminal portions  67  (connecting terminal portions 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. 3 and 5 , the first region R 1  is arranged in the central portion of the case portion  11 . The second region R 2  and the third region R 3  are arranged in a first direction (along arrow X 1 ) and a second direction (along arrow Z 1 ), respectively, orthogonal to the rotating shaft  31  of the motor  3  with respect to the first region R 1 . Thus, the coil switching portion  4  arranged in the second region R 2  and the inverter  1  arranged in the third region R 3  are arranged in the directions orthogonal to the rotating shaft  31  with respect to the motor  3  arranged in the first region R 1 . In the first embodiment, the coil switching portion  4  arranged in the second region R 2  and the inverter  1  arranged in the third region R 3  are arranged at an interval of 90 degrees along the rotational direction of the motor  3 . Specifically, the coil switching portion  4  is arranged in a position rotated counterclockwise by 90 degrees from the arrangement position of the inverter  1 , as shown in  FIG. 5 . 
     In the first embodiment, a single cooling tube  12  to cool the inverter  1 , the motor  3 , and the coil switching portion  4  is provided inside the portion  11   a  in the form of a circular cylinder of the case portion  11 , as shown in  FIGS. 4 and 5 . As shown in  FIG. 5 , the cooling tube  12  is arranged to be held between the motor  3  and the inverter  1  and between the motor  3  and the coil switching portion  4 . Thus, the inverter  1 , the motor  3 , and the coil switching portion  4  are cooled by the same cooling channel (cooling channel constituted by the single cooling tube  12 ). The case portion  11  and the cooling tube  12  inside the case portion  11  are formed by sand mold casting, for example. The cooling tube  12  is an example of the “cooling portion”. 
     As shown in  FIGS. 4 and 5 , the cooling tube  12  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  12  is so configured that a plurality of linear portions  12   a  (see  FIG. 4 ) extending in the 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  12   a  extending in the direction Y, of the cooling tube  12  are bent in the form of a U to be connected to each other on both ends thereof in the direction Y. Thus, the cooling tube  12  constitutes a line of the cooling channel from a first end  12   b  protruding from the outer surface of the portion  11   a  in the form of a circular cylinder opposite to the second region R 2  (along arrow X 2 ) to a second end  12   c  protruding from the outer surface of the portion  11   a  in the form of a circular cylinder opposite to the second region R 2  (along arrow X 2 ), in which cooling water flows. In the first embodiment, the inverter  1  is arranged on the side of the first end  12   b  (entrance of the cooling channel) of the cooling tube  12  while the coil switching portion  4  is arranged on the side of the second end  12   c  (exit of the cooling channel) of the cooling tube  12 , as shown in  FIG. 5 . 
     As shown in  FIGS. 3 and 6 , a first opening  11   e  having a circular shape is provided in a portion of the case portion  11  corresponding to the first region R 1 . This first opening  11   e  is covered with a platelike first lid  13 . The first lid  13  is attached to the portion of the case portion  11  corresponding to the first region R 1  in an openable/closable manner with an unshown screw member or the like. The first lid  13  is configured to cover not only the first opening  11   e  of the case portion  11  but also a portion along arrow Y 1  of a second opening  11   f , described later, of the case portion  11 . In other words, the first lid  13  is integrally provided with a circular portion  13   a  covering the first opening  11   e  of the case portion  11  and a rectangular portion  13   b  covering the portion along arrow Y 1  of the second opening  11   f , described later, of the case portion  11 . A portion between the first lid  13  and the case portion  11  is sealed with an unshown sealing member having a waterproof function. 
     As shown in  FIG. 3 , a substantially disk-shaped partition wall  16  extending in the directions (direction X and direction Z) orthogonal to the rotating shaft  31  of the motor  3  is arranged between the first lid  13  and the motor  3  stored in the first region R 1  of the case portion  11 . A bearing  16   a  connected to the rotating shaft  31  is mounted on the central portion of this partition wall  16 . As shown in  FIGS. 3 ,  6  and  7 , a single hole  16   b  is provided in the vicinity of the central portion of the partition wall  16  in the direction X and a portion of the partition wall  16  along arrow Z 1  to allow the three connecting terminal portions  61  (connecting terminal portions 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  16 . As shown in  FIGS. 6 and 7 , the three connecting terminal portions  61  of the motor  3  passing through the hole  16   b  of the partition wall  16  are screwed on the L-shaped three connecting terminal portions  65 , described later, mounted on the surface of the partition wall  16  opposite to the motor  3  (along arrow Y 1 ). 
     Furthermore, a single notch  16   c  is provided in the vicinity of the central portion of the partition wall  16  in the direction Z and an end of the partition wall  16  along arrow X 1  to allow the six connecting terminal portions  62  (connecting terminal portions corresponding to the aforementioned terminals TU 3 , TV 3 , TW 3 , TU 4 , TV 4 , and TW 4  shown in  FIG. 1 ) of the motor  3  to pass through the partition wall  16 , as shown in  FIGS. 3 ,  6 , and  7 . As shown in  FIG. 6 , the six connecting terminal portions  62  of the motor  3  passing through the notch  16   c  of the partition wall  16  are screwed on the six connecting terminal portions  63  (connecting terminal portions corresponding to the aforementioned terminals TU 5 , TV 5 , TW 5 , TU 6 , TV 6 , and TW 6  shown in  FIG. 1 ) of the coil switching portion  4  arranged on the side along arrow X 1  with respect to the motor  3 . 
     As shown in  FIGS. 3 ,  6 , and  7 , the L-shaped three connecting terminal portions  65  are mounted on a portion in the vicinity of the aforementioned hole  16   b , of the surface of the partition wall  16  opposite to the motor  3  (along arrow Y 1 ). Although not shown in  FIGS. 3 ,  6 , and  7 , the three connecting terminal portions  65  each are mounted on the surface of the partition wall  16  along arrow Y 1  through an insulating member made of resin or the like. As shown in  FIGS. 6 and 7 , the three connecting terminal portions  65  are screwed on the three connecting terminal portions  61  of the motor  3  and the L-shaped three connecting terminal portions  66  screwed on the three connecting terminal portions  64  (connecting terminal portions corresponding to the aforementioned terminals TU 1 , TV 1 , and TW 1  shown in  FIG. 1 ) of the inverter  1 . 
     As shown in  FIGS. 3 and 5 , the second opening  11   f  and a third opening  11   g  each having a rectangular shape are provided in portions of the case portion  11  corresponding to the second region R 2  and the third region R 3 , respectively. These second opening  11   f  and third opening  11   g  are covered with a platelike second lid  14  and a third lid  15  having shapes (rectangular shapes) corresponding to the second opening  11   f  and the third opening  11   g , respectively. The second lid  14  and the third lid  15  are attached to the portions of the case portion  11  corresponding to the second region R 2  and the third region R 3 , respectively, in an openable/closable manner with an unshown screw member or the like. A portion between the second lid  14  and the case portion  11  and a portion between the third lid  15  and the case portion  11  each are sealed with an unshown sealing member having a waterproof function. 
     As shown in  FIGS. 3 and 7 , a single hole  11   i  is provided in an end along arrow Y 1 , of the bottom surface portion  11   h  of a portion of the case portion  11  corresponding to the third region R 3  to allow the L-shaped three connecting terminal portions  66  to pass through the bottom surface portion  11   h . As shown in  FIG. 7 , the three connecting terminal portions  66  passing through the hole  11   i  of the case portion  11  are screwed on the three connecting terminal portions  65  mounted on the partition wall  16  and the three connecting terminal portions  64  of the inverter  1 . Thus, the connecting terminal portions  61  of the motor  3  and the connecting terminal portions  64  of the inverter  1  are electrically connected to each other through the connecting terminal portions  65  and  66 . 
     As shown in  FIGS. 3 and 5 , a fourth region R 4  where the controller  5  is arranged is provided on the side of the third lid  15  opposite to the case portion  11  (along arrow Z 1 ). The fourth region R 4  is a recessed space surrounded by a wall portion  15   a  integrally formed on the third lid  15 . Thus, the third lid  15  serves as a case portion to store the controller  5 . The third lid  15  is an example of the “second case portion”. 
     As shown in  FIGS. 3 and 5 , a fourth opening  15   b  having a rectangular shape smaller than the third opening  11   g  of the case portion  11  is provided in a portion of the third lid  15  corresponding to the fourth region R 4 . This fourth opening  15   b  is covered with a platelike fourth lid  17  having a shape (rectangular shape) corresponding to the fourth opening  15   b . The fourth lid  17  is attached to the portion of the third lid  15  corresponding to the fourth region R 4  in an openable/closable manner with an unshown screw member or the like. A portion between the fourth lid  17  and the portion of the third lid  15  corresponding to the fourth region R 4  is sealed with an unshown sealing member having a waterproof function. 
     As shown in  FIG. 3 , a single through-hole  15   c  is provided in a portion along arrow X 1 , of the wall portion  15   a  surrounding the fourth region R 4  of the third lid  15  to allow a single connecting wire  72  (see  FIG. 2 ) for connecting the controller  5  arranged in the fourth region R 4  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  15   a . As shown in  FIGS. 3 and 7 , a hole  15   e  is provided in an end along arrow Y 1 , of the bottom surface portion  15   d  of a portion of the third lid  15  corresponding to the fourth region R 4  to allow unshown connecting wires, connecting terminal portions, etc. connected to the controller  5  to pass through the bottom surface portion  15   d.    
     According to the first embodiment, as hereinabove described, the motor  3 , the coil switching portion  4 , and the inverter  1  are stored in the single case portion  11 . Thus, formation of a dead space between each case portion can be suppressed, dissimilarly to a case where the motor  3 , the coil switching portion  4 , and the inverter  1  are stored in separate case portions and placed separately. Therefore, a space for the motor driving portion  10  can be saved. Furthermore, no separate case portion to store the motor  3 , the coil switching portion  4 , and the inverter  1  may be provided, and hence the number of components can be reduced. These effects are 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 the first embodiment, connecting wires to electrically connect the motor  3 , the coil switching portion  4 , and the inverter  1  can be also stored in the single case portion  11 . 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 case portion  11 . Thus, the space for the motor driving portion  10  can be further saved. 
     According to the first embodiment, the connecting wires to electrically connect the motor  3 , the coil switching portion  4 , and the inverter  1  are stored in the single case portion  11 . Therefore, 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 case portion  11 . Thus, 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 the first embodiment, as hereinabove described, the coil switching portion  4  and the inverter  1  are arranged in the directions (along arrow X 1  and arrow Z 1 ) orthogonal to the rotating shaft  31  with respect to the motor  3 . Thus, the size (length in the axial direction) of the motor driving portion  10  can be further reduced as compared with a case where the coil switching portion  4 , the inverter  1 , and the motor  3  are aligned in a direction (axial direction: direction Y) along the rotating shaft  31 . Consequently, the space for the motor driving portion  10  in the axial direction can be saved. 
     According to the first embodiment, as hereinabove described, the single cooling tube  12  is placed to be held between the motor  3  and the coil switching portion  4  and between the motor  3  and the inverter  1 . Thus, the motor  3 , the coil switching portion  4 , and the inverter  1  (three heating elements) can be efficiently cooled by the single cooling tube  12 . 
     According to the first embodiment, as hereinabove described, the inverter  1  is arranged on the side of the first end  12   b  (entrance of the cooling channel) of the cooling tube  12  while the coil switching portion  4  is arranged on the side of the second end  12   c  (exit of the cooling channel) of the cooling tube  12 . Thus, the inverter  1  in which switching is performed more frequently than in the coil switching portion  4  so that the temperature tends to rise can be arranged on the entrance side of the cooling channel in which colder cooling water flows as compared with the exit side of the cooling channel. Consequently, the inverter  1  and the coil switching portion  4  can be effectively cooled. 
     According to the first embodiment, as hereinabove described, the first region R 1  where the motor  3  is arranged is provided in the central portion of the case portion  11 , the second region R 2  where the coil switching portion  4  is arranged is provided on the side along arrow X 1  orthogonal to the rotating shaft  31  with respect to the first region R 1 , and the third region R 3  where the inverter  1  is arranged is provided on the side along arrow Z 1  orthogonal to the rotating shaft  31  with respect to the first region R 1 . Namely, the motor  3 , the coil switching portion  4 , and the inverter  1  are arranged in the first region R 1 , the second region R 2 , and the third region R 3 , respectively. Thus, the coil switching portion  4  and the inverter  1  can be easily arranged in the directions (along arrow X 1  and arrow Z 1 ) orthogonal to the rotating shaft  31  with respect to the motor  3 . 
     According to the first embodiment, as hereinabove described, the 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 . Furthermore, the first region R 1  is arranged on the inner surface side of the portion  11   a  in the form of a circular cylinder, and the second region R 2  and the third region R 3  are 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 case portion  11  by utilizing a region on the inner surface side of the portion  11   a  in the form of a circular cylinder. The second region R 2  and the third region R 3  can be easily provided in the directions (along arrow X 1  and arrow Z 1 ) orthogonal to the rotating shaft  31  with respect to the first region R 1  of the case portion  11  by utilizing regions on the outer surface side of the portion  11   a  in the form of a circular cylinder. 
     According to the first embodiment, as hereinabove described, the first opening  11   e , the second opening  11   f , and the third opening  11   g  are provided in the portions of the case portion  11  corresponding to the first region R 1 , the second region R 2 , and the third region R 3 , respectively. Thus, access to (work on) the motor  3  arranged in the first region R 1 , the coil switching portion  4  arranged in the second region R 2 , and the inverter  1  arranged in the third region R 3  can be easily facilitated through the first opening  11   e , the second opening  11   f , and the third opening  11   g  in assembling or during maintenance. 
     According to the first embodiment, as hereinabove described, the first lid  13 , the second lid  14 , and the third lid  15  are provided in an openable/closable manner to cover the first opening  11   e , the second opening  11   f , and the third opening  11   g , respectively. Thus, the first lid  13 , the second lid  14 , and the third lid  15  covering the first opening ile, the second opening  11   f , and the third opening  11   g , respectively can suppress entry of foreign matter through the first opening  11   e , the second opening  11   f , and the third opening  11   g.    
     According to the first embodiment, as hereinabove described, the smoothing condenser  2  smoothing power input to the inverter  1  is arranged in the third region R 3  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 the first embodiment, as hereinabove described, the controller  5  controlling the coil switching portion  4  and the inverter  1  is arranged in the fourth region R 4  of the third lid  15  for covering the third opening  11   g  of the 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 third lid  15 . 
     According to the first embodiment, as hereinabove described, the fourth opening  15   b  is provided in the portion of the third lid  15  corresponding to the fourth region R 4  where the controller  5  is arranged, and the fourth lid  17  is provided in an openable/closable manner to cover the fourth opening  15   b . Thus, access to (work on) the controller  5  arranged in the fourth region R 4  of the third lid  15  can be easily facilitated through the fourth opening  15   b  in assembling or during maintenance. Furthermore, the fourth lid  17  covering the fourth opening  15   b  can suppress entry of foreign matter through the fourth opening  15   b.    
     According to the first embodiment, as hereinabove described, the coil switching portion  4  and the inverter  1  are arranged at an interval of 90 degrees along the rotational direction of the motor  3 . Thus, the length of the motor driving portion  10  in the direction X (transverse direction) or the direction Z (vertical direction) can be further reduced as compared with a case where the coil switching portion  4 , the motor  3 , and the inverter  1  are aligned along a direction (direction X or direction Z, for example) intersecting with the rotating shaft  31 . Consequently, the space for the motor driving portion  10  can be effectively saved. 
     According to the first embodiment, as hereinabove described, 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 a 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 a SiC semiconductor having excellent heat resistance, and hence 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). 
     Second Embodiment 
     Next, the structure of a motor driving portion  110  according to a second embodiment is described with reference to  FIGS. 8 to 11 . In this second embodiment, a high speed coil switching portion  4   a  and a low speed coil switching portion  4   b  are configured as separate modules, dissimilarly to the aforementioned first embodiment in which the high speed coil switching portion  4   a  and the low speed coil switching portion  4   b  constituting the coil switching portion  4  are integrated as a single module. The motor driving portion  110  is an example of the “motor driving device”. The high speed coil switching portion  4   a  and the low speed coil switching portion  4   b  are examples of the “first coil switching portion” and the “second coil switching portion”, respectively. 
     As shown in  FIGS. 8 to 11 , an inverter  1 , a smoothing condenser  2 , a motor  3 , the high speed coil switching portion  4   a , and the low speed coil switching portion  4   b  of the motor driving portion  110  according to the second embodiment are stored in a single case portion  111  made of metal (cast metal) such as aluminum. This case portion  111  includes a portion  11   a  in the form of a circular cylinder extending along the axial direction (direction Y) of the motor  3 , similarly to the aforementioned first embodiment. The case portion  111  is an example of the “first case portion”. 
     As shown in  FIGS. 9 and 10 , the motor  3  is arranged in a first region R 1  surrounded by the inner surface of the portion  11   a  in the form of a circular cylinder, similarly to the aforementioned first embodiment. The inverter  1  is arranged in a third region R 3  surrounded by a rectangular wall portion  11   c  formed to protrude along arrow Z 1  from the outer surface of the portion  11   a  in the form of a circular cylinder. 
     In the second embodiment, the high speed coil switching portion  4   a  and the low speed coil switching portion  4   b  are arranged separately from each other as the separate modules on the outer surface side of the portion  11   a  in the form of a circular cylinder of the case portion  111 , as shown in  FIGS. 9 to 11 . Specifically, the high speed coil switching portion  4   a  (low speed coil switching portion  4   b ) is arranged in a second region R 2   a  (R 2   b ) surrounded by a rectangular wall portion  111   b  formed to protrude along arrow X 2  (arrow X 1 ) from the outer surface of the portion  11   a  in the form of a circular cylinder. 
     As shown in  FIG. 10 , the high speed coil switching portion  4   a  (low speed coil switching portion  4   b ) arranged in the second region R 2   a  (R 2   b ) and the inverter  1  arranged in the third region R 3  are arranged at an interval of 90 degrees along the rotational direction of the motor  3 . Specifically, the high speed coil switching portion  4   a  (low speed coil switching portion  4   b ) is arranged in a position rotated clockwise (counterclockwise) by 90 degrees from the arrangement position of the inverter  1 . Thus, the high speed coil switching portion  4   a  and the low speed coil switching portion  4   b  are arranged at an interval of 180 degrees along the rotational direction of the motor  3 . In other words, the high speed coil switching portion  4   a  and the low speed coil switching portion  4   b  are linearly arranged in symmetric positions in a direction X (horizontal direction) through the motor  3 . 
     As shown in  FIG. 9 , a first opening  11   e  similar to the first opening  11   e  according to the aforementioned first embodiment is provided in a portion of the case portion  111  corresponding to the first region R 1 . This first opening  11   e  is covered with a platelike first lid  113 . In the second embodiment, the first lid  113  is configured to cover not only the first opening  11   e  of the case portion  111  but also portions along arrow Y 1 , of a pair of second openings  111   f , described later, provided on both sides of the case portion  111  in the direction X. In other words, the first lid  113  is integrally provided with a circular portion  113   a  covering the first opening  11   e  of the case portion  111  and a pair of rectangular portions  113   b  covering the portions along arrow Y 1 , of the pair of second openings  111   f , described later, of the case portion  111 , as shown in  FIGS. 9 and 10 . 
     In the second embodiment, a substantially disk-shaped partition wall  116  is arranged between the motor  3  stored in the first region R 1  of the case portion  111  and the first lid  113 , as shown in  FIG. 9 . This partition wall  116  has a bearing  16   a  and a hole  16   b  similar to the bearing  16   a  and the hole  16   b  according to the aforementioned first embodiment. As shown in  FIGS. 9 and 11 , a pair of notches  116   c  are provided in the vicinity of the central portion of the partition wall  116  in the direction Z and both ends of the partition wall  116  in the direction X to allow six connecting terminal portions  62  (connecting terminal portions corresponding to the aforementioned terminals TU 3 , TV 3 , TW 3 , TU 4 , TV 4 , and TW 4  shown in  FIG. 1 ) of the motor  3  to pass through the partition wall  116 . As shown in  FIG. 11 , the six connecting terminal portions  62  of the motor  3  passing through the pair of notches  116   c  of the partition wall  116  are screwed on three connecting terminal portions  63  (connecting terminal portions corresponding to the aforementioned terminals TU 5 , TV 5 , and TW 5  shown in  FIG. 1 ) of the high speed coil switching portion  4   a  arranged in the second region R 2   a  of the case portion  111  and three connecting terminal portions  63  (connecting terminal portions corresponding to the aforementioned terminals TU 6 , TV 6 , and TW 6  shown in  FIG. 1 ) of the low speed coil switching portion  4   b  arranged in the second region R 2   b.    
     In the second embodiment, the pair of rectangular second openings  111   f  are provided in portions corresponding to a pair of second regions R 2   a  and R 2   b  provided on both sides of the case portion  111  in the direction X, as shown in  FIGS. 9 and 10 . The pair of second openings  111   f  are covered with a pair of platelike second lids  114  having shapes (rectangular shapes) corresponding to the second openings  111   f . The pair of second lids  114  are attached to the portions of the case portion  111  corresponding to the pair of second regions R 2   a  and R 2   b  in an openable/closable manner with unshown screw members or the like. 
     The remaining structure of the second embodiment is similar to that of the aforementioned first embodiment. 
     According to the second embodiment, as hereinabove described, the coil switching portion  4  is divided into the high speed coil switching portion  4   a  and the low speed coil switching portion  4   b . Thus, the operation of connecting the coil switching portion  4  and the motor  3  can be divided into the operation of connecting the high speed coil switching portion  4   a  and the motor  3  and the operation of connecting the low speed coil switching portion  4   b  and the motor  3 . Consequently, workability can be improved. 
     According to the second embodiment, as hereinabove described, the high speed coil switching portion  4   a  and the low speed coil switching portion  4   b  are arranged in the symmetric positions in the direction X (horizontal direction) through the motor  3 . Thus, the operation of connecting the high speed coil switching portion  4   a  and a coil  3   a  of the motor  3  for high speed drive and the operation of connecting the low speed coil switching portion  4   b  and a coil  3   b  of the motor  3  for low speed drive can be performed in positions separate from each other in the direction X. Consequently, workability can be further improved. 
     The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment. 
     Third Embodiment 
     Next, the structure of a motor driving portion  210  according to a third embodiment is described with reference to  FIGS. 12 to 15 . In this third embodiment, a coil switching portion  4  is arranged on the opposite side to an inverter  1  with respect to a motor  3 , dissimilarly to the aforementioned first embodiment in which the inverter  1  and the coil switching portion  4  are arranged at an interval of 90 degrees along the rotational direction of the motor  3 . The motor driving portion  210  is an example of the “motor driving device”. 
     As shown in  FIGS. 12 to 15 , the inverter  1 , a smoothing condenser  2 , the motor  3 , and the coil switching portion  4  of the motor driving portion  210  according to the third embodiment are stored in a single case portion  211  made of metal (cast metal) such as aluminum. This case portion  211  includes a portion  11   a  in the form of a circular cylinder extending along the axial direction (direction Y) of the motor  3 , similarly to the aforementioned first embodiment. The case portion  211  is an example of the “first case portion”. 
     As shown in  FIGS. 13 and 14 , the motor  3  is arranged in a first region R 1  surrounded by the inner surface of the portion  11   a  in the form of a circular cylinder, similarly to the aforementioned first embodiment. The inverter  1  is arranged in a third region R 3  surrounded by a rectangular wall portion  11   c  formed to protrude along arrow Z 1  from the outer surface of the portion  11   a  in the form of a circular cylinder. 
     In the third embodiment, the coil switching portion  4  is arranged in a second region R 2   c  surrounded by a rectangular wall portion  211   b  formed to protrude from the outer surface of the portion  11   a  in the form of a circular cylinder to the opposite side (along arrow Z 2 ) to the third region R 3 , as shown in  FIGS. 13 and 14 . Thus, the coil switching portion  4  and the inverter  1  are arranged at an interval of 180 degrees along the rotational direction of the motor  3 . In other words, the coil switching portion  4  and the inverter  1  are linearly arranged in symmetric positions in a direction Z (vertical direction) through the motor  3 . 
     As shown in  FIG. 14 , a second opening  211   f  is provided in a portion along arrow Z 2  of the case portion  111  corresponding to the second region R 2   c . This second opening  211   f  is covered with a platelike second lid  214  (see  FIG. 13 ) having a rectangular shape. The second lid  214  is attached to the portion of the case portion  211  corresponding to the second region R 2   c  in an openable/closable manner with an unshown screw member or the like. 
     As shown in  FIG. 13 , a first opening  11   e  similar to the first opening ile according to the aforementioned first embodiment is provided in a portion of the case portion  211  corresponding to the first region R 1 . This first opening ile is covered with a platelike first lid  213 . The first lid  213  is configured to cover not only the first opening  11   e  of the case portion  211  but also a portion along arrow Y 1 , of the aforementioned second opening  211   f  of the case portion  211 . In other words, the first lid  213  is integrally provided with a circular portion  213   a  covering the first opening  11   e  of the case portion  211  and a rectangular portion  213   b  covering the portion along arrow Y 1 , of the second opening  211   f  of the case portion  211 , as shown in  FIGS. 13 and 14 . 
     In the third embodiment, a substantially disk-shaped partition wall  216  is arranged between the motor  3  stored in the first region R 1  of the case portion  211  and the first lid  213 , as shown in  FIG. 13 . This partition wall  216  has a bearing  16   a  and a hole  16   b  similar to the bearing  16   a  and the hole  16   b  according to the aforementioned first embodiment. A notch  216   c  is provided in the vicinity of the central portion of the partition wall  216  in a direction X and an end of the partition wall  216  along arrow Z 2  to allow six connecting terminal portions  62  (connecting terminal portions corresponding to the aforementioned terminals TU 3 , TV 3 , TW 3 , TU 4 , TV 4 , and TW 4  shown in  FIG. 1 ) of the motor  3  to pass through the partition wall  216 . As shown in  FIG. 15 , the six connecting terminal portions  62  of the motor  3  passing through the notch  216   c  of the partition wall  216  are screwed on six connecting terminal portions  63  (connecting terminal portions corresponding to the aforementioned terminals TU 5 , TV 5 , TW 5 , TU 6 , TV 6 , and TW 6  shown in  FIG. 1 ) of the coil switching portion  4  arranged in the second region R 2   c  of the case portion  211 . 
     The remaining structure of the third embodiment is similar to that of the aforementioned first embodiment. 
     According to the third embodiment, as hereinabove described, the coil switching portion  4  and the inverter  1  are arranged in the symmetric positions in the direction Z through the motor  3 . Thus, the operation of connecting the coil switching portion  4  and the motor  3  and the operation of connecting the inverter  1  and the motor  3  can be performed in positions separate from each other in the direction Z, and hence workability can be improved. 
     The remaining effects of the third embodiment are similar to those of the aforementioned first embodiment. 
     Fourth Embodiment 
     Next, the structure of a motor driving portion  310  according to a fourth embodiment is described with reference to  FIGS. 16 to 19 . In this fourth embodiment, a coil switching portion  4  is arranged on the opposite side to an inverter  1  with respect to a motor  3 , similarly to the aforementioned third embodiment, and the motor  3  and the coil switching portion  4  are connected to each other through a pair of terminal blocks  81  arranged in a case portion  311 . The motor driving portion  310  is an example of the “motor driving device”. The case portion  311  is an example of the “first case portion”. 
     As shown in  FIGS. 16 to 19 , the inverter  1 , a smoothing condenser  2 , the motor  3 , and the coil switching portion  4  of the motor driving portion  310  according to the fourth embodiment are stored in the single case portion  311  made of metal (cast metal) such as aluminum. This case portion  311  includes a portion  11   a  in the form of a circular cylinder extending along the axial direction (direction Y) of the motor  3 , similarly to the aforementioned third embodiment. 
     As shown in  FIGS. 17 and 18 , the motor  3  is arranged in a first region R 1  surrounded by the inner surface of the portion  11   a  in the form of a circular cylinder, similarly to the aforementioned third embodiment. The inverter  1  is arranged in a third region R 3  surrounded by a rectangular wall portion  11   c  formed to protrude along arrow Z 1  from the outer surface of the portion  11   a  in the form of a circular cylinder. In the fourth embodiment, the coil switching portion  4  is arranged in a second region R 2   d  surrounded by a rectangular wall portion  311   b  formed to protrude along arrow Z 2  from the outer surface of the portion  11   a  in the form of a circular cylinder. 
     As shown in  FIG. 17 , a first opening  11   e  similar to the first opening  11   e  according to the aforementioned third embodiment is provided in a portion of the case portion  311  corresponding to the first region R 11 . This first opening  11   e  is covered with a platelike first lid  313  having a shape (circular shape) corresponding to the first opening  11   e . As shown in  FIG. 18 , a rectangular second opening  311   f  is provided in a portion along arrow Z 2  of the case portion  311  corresponding to the second region R 2   d . This second opening  311   f  is covered with a platelike second lid  314  having a shape (rectangular shape) corresponding to the second opening  311   f.    
     As shown in  FIG. 17 , a substantially disk-shaped partition wall  316  is arranged between the motor  3  stored in the first region R 1  of the case portion  311  and the first lid  313 . This partition wall  316  has a bearing  16   a  and a hole  16   b  similar to the bearing  16   a  and the hole  16   b  according to the aforementioned third embodiment. A pair of notches  316   c  are provided in the vicinity of the central portion of the partition wall  316  in a direction Z and both ends of the partition wall  316  in a direction X (horizontal direction) to allow six connecting terminal portions  62  (connecting terminal portions corresponding to the aforementioned terminals TU 3 , TV 3 , TW 3 , TU 4 , TV 4 , and TW 4  shown in  FIG. 1 ) of the motor  3  to pass through the partition wall  316 . As shown in  FIG. 19 , the six connecting terminal portions  62  of the motor  3  passing through the pair of notches  316   c  of the partition wall  316  are screwed on the pair of terminal blocks  81 , described later, arranged on the inner surface of the portion  11   a  in the form of a circular cylinder of the case portion  311 . 
     In the fourth embodiment, the pair of terminal blocks  81  are arranged in portions along arrow Y 1  and on both sides in the direction X, of the inner surface of the portion  11   a  in the form of a circular cylinder to electrically connect the motor  3  and the coil switching portion  4  to each other, as shown in  FIGS. 17 and 19 . The pair of terminal blocks  81  are arranged to be opposed to each other in a direction (i.e., direction X) orthogonal to a rotating shaft  31  of the motor  3  and orthogonal to a direction in which the coil switching portion  4  and the inverter  1  are arranged with respect to the motor  3 . 
     As shown in  FIG. 19 , the three connecting terminal portions  62  corresponding to the terminals TU 3 , TV 3 , and TW 3  (TU 4 , TV 4 , and TW 4 ) of the motor  3  are arranged in this order along arrow Z 2  on each of the pair of terminal blocks  81  opposed to each other in the direction X. In the vicinity of ends of the pair of terminal blocks  81  along arrow Z 1  (portions where the connecting terminal portions  62  corresponding to the terminals TU 3  and TU 4  of the motor  3  are arranged), connecting terminal portions  91   a  provided on tips of connecting wires  91  extending in the direction Z are screwed through columnar connecting terminal portions  82  extending in the direction X. Similarly, also in intermediate portions of the pair of terminal blocks  81  in the direction Z (portions where the connecting terminal portions  62  corresponding to the terminals TV 3  and TV 4  of the motor  3  are arranged), connecting terminal portions  91   a  provided on tips of connecting wires  91  extending in the direction Z are screwed through columnar connecting terminal portions  83  extending in the direction X (horizontal direction). 
     As shown in  FIG. 19 , the length of each of the connecting terminal portions  82  in the direction X is larger than the length of each of the connecting terminal portions  83  in the direction X. Specifically, portions of the connecting terminal portions  82  where the connecting terminal portions  91   a  are screwed are arranged inward (on the side of the rotating shaft  31 ) beyond portions of the connecting terminal portions  83  where the connecting terminal portions  91   a  are screwed. Thus, the connecting wires  91  having the connecting terminal portions  91   a  screwed on the connecting terminal portions  82  are arranged in positions deviating in the direction X with respect to the connecting wires  91  having the connecting terminal portions  91   a  screwed on the connecting terminal portions  83 . Consequently, the connecting wires  91  having the connecting terminal portions  91   a  screwed on the connecting terminal portions  82  and the connecting wires  91  having the connecting terminal portions  91   a  screwed on the connecting terminal portions  83  can be inhibited from interfering with each other. 
     Furthermore, as shown in  FIG. 19 , in the vicinity of ends of the pair of terminal blocks  81  along arrow Z 2  (portions where the connecting terminal portions  62  corresponding to the terminals TW 3  and TW 4  of the motor  3  are arranged), connecting terminal portions  91   a  provided on tips of connecting wires  91  extending in the direction Z are screwed directly. Thus, the connecting wires  91  having the connecting terminal portions  91   a  screwed in the vicinity of the ends of the terminal blocks  81  along arrow Z 2  are arranged in positions deviating in the direction X with respect to the connecting wires  91  having the connecting terminal portions  91   a  screwed on the terminal blocks  81  through the connecting terminal portions  82  and  83  having the aforementioned lengths in the direction X different from each other. Consequently, the connecting wires  91  having the connecting terminal portions  91   a  screwed in the vicinity of the ends of the terminal blocks  81  along arrow Z 2  and the connecting wires  91  having the connecting terminal portions  91   a  screwed on the terminal blocks  81  through the connecting terminal portions  82  and  83  can be inhibited from interfering with each other. 
     Although not shown in  FIG. 19 , the aforementioned six connecting wires  91  screwed on the pair of terminal blocks  81  also have connecting terminal portions similar to the connecting terminal portions  91   a  on ends opposite to the connecting terminal portions  91   a . The connecting terminal portions provided on the ends opposite to the connecting terminal portions  91   a  of these six connecting wires  91  are electrically connected to unshown six connecting terminal portions (connecting terminals corresponding to the aforementioned terminals TU 5 , TV 5 , TW 5 , TU 6 , TV 6 , and TW 6  shown in  FIG. 1 ) of the coil switching portion  4  arranged in the second region R 2   d  of the case portion  311  through a hole  311   j  (see  FIG. 17 ) provided in the vicinity of an end along arrow Y 1  and arrow Z 2 , of the inner surface of the portion  11   a  in the form of a circular cylinder. 
     The remaining structure of the fourth embodiment is similar to that of the aforementioned third embodiment. 
     According to the fourth embodiment, as hereinabove described, the terminal blocks  81  are provided in the case portion  311  to electrically connect the motor  3  and the coil switching portion  4  to each other. Thus, the motor  3  and the coil switching portion  4  can be easily electrically connected to each other through the terminal blocks  81 . 
     The remaining effects of the fourth embodiment are similar to those of the aforementioned third embodiment. 
     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 each of the aforementioned first to fourth embodiments, the motor driving portion (motor driving device) is loaded into 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 each of the aforementioned first to fourth embodiments, the coil switching portion and the inverter are arranged in the direction(s) orthogonal to the rotating shaft of the motor with respect to the motor. Nevertheless, the coil switching portion, the inverter, and the motor may alternatively be sequentially arranged in the direction along the rotating shaft of the motor in a single case portion extending along the rotating shaft of the motor. 
     In each of the aforementioned first to fourth embodiments, the motor, the coil switching portion, and the inverter are water-cooled. Nevertheless, the motor, the coil switching portion, and the inverter may alternatively be cooled with cooling means (air-cooling, a cooling element, etc., for example) other than water-cooling. 
     In each of the aforementioned first to fourth embodiments, the cooling tube is arranged to be held between the motor and the coil switching portion and between the motor and the inverter. Nevertheless, the cooling tube may alternatively be arranged only either between the motor and the coil switching portion or between the motor and the inverter. 
     In each of the aforementioned first to fourth embodiments, the motor, the coil switching portion, and the inverter are cooled by the same cooling channel (single cooling tube). Nevertheless, the motor, the coil switching portion, and the inverter may alternatively be cooled by separate cooling tubes. 
     In each of the aforementioned first to fourth embodiments, the motor, the coil switching portion, and the inverter are arranged in the three regions (the first region, the second region, and the third region) provided separately on the inner surface side and the outer surface side of the portion in the form of a circular cylinder. Nevertheless, the motor, the coil switching portion, and the inverter may alternatively be arranged in a single region formed inside a single case portion. 
     In each of the aforementioned first to fourth embodiments, the case portion storing the motor, the coil switching portion, and the inverter 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 coil switching portion and the inverter are 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 coil switching portion and the inverter may alternatively be arranged on the outer surface side of the portion in the form of a rectangular cylinder. 
     In each of the aforementioned first to fourth embodiments, 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 each of the aforementioned first to fourth embodiments, a case portion (second case portion) to store the controller is integrally provided on the third lid. Nevertheless, the case portion (second case portion) to store the controller may alternatively be integrally provided on the first lid or the second lid other than the third lid. Furthermore, a dedicated case portion for storing the controller may alternatively be provided separately from the first lid, the second lid, and the third lid. 
     In the aforementioned first embodiment (second embodiment), the coil switching portion (the high speed coil switching portion and the low speed coil switching portion) and the inverter are arranged at an interval of 90 degrees along the rotational direction of the motor. Nevertheless, the coil switching portion (the high speed coil switching portion and the low speed coil switching portion) and the inverter may alternatively be arranged at an interval of an angle less than 90 degrees or an angle more than 90 degrees along the rotational direction of the motor. 
     In the aforementioned second embodiment, the high speed coil switching portion and the low speed coil switching portion are arranged at an interval of 180 degrees along the rotational direction of the motor to be opposed to each other with respect to the motor. Nevertheless, the high speed coil switching portion and the low speed coil switching portion may alternatively be arranged at an interval of an angle less than 180 degrees along the rotational direction of the motor. 
     In each of the aforementioned third and fourth embodiments, the coil switching portion and the inverter are arranged at an interval of 180 degrees along the rotational direction of the motor to be opposed to each other with respect to the motor. Nevertheless, the coil switching portion and the inverter may alternatively be arranged at an interval of an angle less than 180 degrees along the rotational direction of the motor. 
     In each of the aforementioned first to fourth embodiments, 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 a 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 a SiC semiconductor, or constituted by switching elements other than the switching elements each containing a semiconductor.