Abstract:
This power control unit, which stores a power conversion module and a rapid charging device used when charging a battery, is provided with a power conversion chamber, which houses the power conversion module, and a charging device chamber, which houses the charging device, the power conversion chamber and the charging device chamber have a bottom surface in common with each other, the power conversion module and the charging device are affixed to the bottom surface in the respectively corresponding chambers, and an ECU that controls the power conversion module is disposed at a position that is above the charging device and enclosed by a peripheral wall that includes the partition wall that partitions the charging device chamber and the power conversion chamber.

Description:
TECHNICAL FIELD 
     The present invention relates to a power control unit including an electric power converter module having a switching element and configured to convert direct-current power into alternating current and a controller configured to control the electric power converter module, wherein the controller is protected from noise generated by the switching element of the electric power converter module. 
     BACKGROUND ART 
     Heretofore, there has been a situation in which noise is produced by the switching element of an inverter circuit and the noise adversely affects a controller for controlling the inverter circuit. Thus, there has been devised a controller layout in view of the adverse effect of the noise produced by the switching element. 
     Japanese Laid-Open Patent Publication No. 2010-035347 discloses that, in view of noise produced by a power module that includes an inverter circuit (having switching elements), an electric power converter is of a three-layer structure and a control circuit board is disposed on the uppermost layer and isolated by a metal base plate for blocking the noise. 
     SUMMARY OF INVENTION 
     According to the technology disclosed in Japanese Laid-Open Patent Publication No. 2010-035347, however, since the casing of the electric power converter is of a three-layer structure for housing the inverter circuit, a controller, etc. therein, the casing is large in size. 
     It is an object of the present invention to provide a power control unit which reduces the adverse effect of noise produced by an electric power converter module and which can be reduced in size. 
     According to the present invention, there is provided a power control unit mounted on a vehicle, the power control unit housing therein an electric power converter module and a charging device configured to be used when a battery mounted on the vehicle is charged from an external source, the power control unit including an electric power converter chamber housing the electric power converter module therein, and a charging device chamber housing the charging device therein, wherein the electric power converter chamber and the charging device chamber have a common bottom surface, and the electric power converter module and the charging device are fixed to the bottom surface respectively in the corresponding chambers, the power control unit further including a controller configured to control the electric power converter module, the controller being disposed in a position above the charging device and surrounded by a peripheral wall which includes a partition wall separating the charging device chamber and the electric power converter chamber from each other. 
     As described above, the power control unit has the electric power converter chamber housing the electric power converter module therein and the charging device chamber housing the charging device therein, and the controller for controlling the electric power converter module is disposed in a position above the charging device and surrounded by the peripheral wall which includes the partition wall that separates the charging device chamber and the electric power converter chamber from each other. Consequently, noise from the electric power converter module is blocked by the partition wall. Therefore, the adverse effect that noise from the electric power converter module may otherwise have on the controller can be reduced. Since the charging device does not operate while the controller is in operation, the controller is not adversely affected by noise from the charging device. On the other hand, while the charging device is in use, the charging device produces noise. However, as the controller is not in operation, there is no need to worry about noise from the charging device. 
     The electric power converter chamber and the charging device chamber may have respective openings. Therefore, the electric power converter module and the charging device have improved maintainability and can easily be serviced for maintenance. 
     The controller may be mounted on the peripheral wall. The charging device chamber may be higher than the electric power converter chamber, and the controller may be mounted on the partition wall of the charging device chamber which is disposed in a position higher than the electric power converter chamber. The partition wall effectively blocks noise from the electric power converter module, so that the adverse effect that noise from the electric power converter module may otherwise have on the controller can be further reduced. 
     The charging device may include a quick charging device and have quick charging contactors. 
     With the power control unit according to the present invention, noise from the electric power converter module is blocked by the partition wall. Therefore, the adverse effect of noise caused by the electric power converter module on the controller can be reduced. Since the charging device does not operate while the controller is in operation, the controller is not adversely affected by noise from the charging device. On the other hand, while the charging device is in use, the charging device produces noise. However, as the controller is not in operation, there is no need to worry about noise from the charging device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view schematically showing a general arrangement of an electric vehicle according to an embodiment of the present invention; 
         FIG. 2  is a side elevational view schematically showing the general arrangement of the electric vehicle according to the embodiment; 
         FIG. 3  is a perspective view of a power control unit shown in  FIG. 1 ; 
         FIG. 4  is an exploded perspective view of the power control unit shown in  FIG. 3 ; 
         FIG. 5  is a top plan view of a heat sink shown in  FIG. 4 ; 
         FIG. 6  is a bottom plan view of a lower case shown in  FIG. 4 ; 
         FIG. 7  is a circuit diagram of the power control unit; 
         FIG. 8  is a top plan view of the heat sink shown in  FIG. 5  with an upper case disposed on an upper portion thereof; 
         FIG. 9  is a view illustrating the manner in which an ECU is installed in a charging device chamber; and 
         FIG. 10  is a fragmentary cross-sectional view of the power control unit with the ECU installed therein. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An electric vehicle which has a power control unit according to a preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 
       FIG. 1  is a perspective view schematically showing a general arrangement of an electric vehicle (vehicle)  10 , and  FIG. 2  is a side elevational view schematically showing the general arrangement of the electric vehicle  10 . In the present embodiment, the vertical directions of a vehicle body  12  of the electric vehicle  10  are referred to as up and down directions, and directions perpendicular to the vertical directions are referred to as horizontal directions. The direction in which the electric vehicle  10  travels forwardly is referred to as a forward direction, and the direction in which the electric vehicle  10  reverses is referred to as a rearward direction. Further, the direction on the left side as viewed along the forward direction is referred to as a leftward direction, and the direction on the right side as viewed along the forward direction is referred to as a rightward direction. 
     The electric vehicle  10  has, housed in the vehicle body  12 , a battery  18  for outputting a high voltage, disposed on the bottom of the vehicle body  12  between front wheels  14 L,  14 R and rear wheels  16 L,  16 R, a passenger compartment  22  defined above the battery  18  with a floor panel  20  interposed therebetween, a motor room  24  defined in a front area of the vehicle body  12  and isolated from the passenger compartment  22 , a dash panel  26  covering the motor room  24 , and a power control unit  30  disposed below the dash panel  26  and placed above a traction motor  28  that is disposed in the motor room  24 . The dash panel  26  has a lower dash panel member  26   a  and an upper dash panel member  26   b . The dash panel  26  serves to separate the motor room  24  and the passenger compartment  22  from each other and has a structure for preventing the entry of dirt, water, odor, etc. from the motor room  24 . The dash panel  26  also has a water discharging function to prevent external water from flowing into A/C (air conditioner) pipes. 
     Power supply cables  34  serve to transmit electric power stored in the battery  18  to the power control unit  30 . The power supply cables  34  have ends connected to a power supply connector  36  of the battery  18  and other ends connected to power supply connectors  94  (see  FIG. 7 ) of the power control unit  30 . The power control unit  30  converts DC electric power from the battery  18  into three-phase (U, V, W phases) AC electric power, and supplies the three-phase AC electric power to the traction motor  28  thereby to energize the traction motor  28 . 
     The power control unit  30  has an electric power converter module  60  (see  FIGS. 4, 5, 7 ) for converting direct-current electric power into three-phase alternating current, and an ECU  70  (see  FIGS. 4, 7, 9 ) for controlling the electric power converter module  60  to energize the traction motor  28 . The traction motor  28  and the power control unit  30  are connected to each other by three-phase AC electric power cables (electric power supply lines)  38 , which have ends connected to electric power connectors  40  of the traction motor  28  and other ends connected to electric power connectors  42  (electric power connectors  42   a ,  42   b ,  42   c ) of the power control unit  30 . Since the power control unit  30  is disposed above the traction motor  28 , the high-voltage three-phase AC electric power cables  38  can be shortened. 
       FIG. 3  shows the power control unit  30  in perspective, and  FIG. 4  shows the power control unit  30  in exploded perspective. The power control unit  30  includes a heat sink  50 , an upper case  52  mounted on an upper portion of the heat sink  50 , an upper cover  54  covering an upper portion of the upper case  52 , a lower case  56  mounted on a lower portion of the heat sink  50 , and a lower cover  58  covering a lower portion of the lower case  56 . Of the heat sink  50 , the upper case  52 , the upper cover  54 , the lower case  56 , and the lower cover  58 , at least the upper case  52  is made of metal such as aluminum or the like. The heat sink  50 , the upper case  52 , the upper cover  54 , the lower case  56 , and the lower cover  58  jointly make up a casing of the power control unit  30 . 
     The electric power converter module  60  is disposed substantially centrally on the upper surface of the heat sink  50 . A quick charging device (charging device)  62  for use in charging the battery  18  from an external source, fuses  98   a ,  98   b  (see  FIGS. 5, 7 ), etc. are disposed on a right region of the upper surface of the heat sink  50 . Three-phase terminals  64   a ,  64   b ,  64   c  that interconnect the electric power converter module  60  and the electric power connectors  42   a ,  42   b ,  42   c  on the upper case  52  are disposed upwardly of a left region of the heat sink  50 . The electric power converter module  60  converts DC electric power from the battery  18  into AC electric power in three phases (U, V, W phases), and supplies the AC electric power in the three phases to the respective three-phase terminals  64   a ,  64   b ,  64   c . The three-phase terminals  64   a ,  64   b ,  64   c  have respective middle portions which are supported on a three-phase terminal base  66  mounted on the left region of the upper surface of the heat sink  50 . 
     The electric power converter module  60  comprises a switching module having a plurality of switching elements, the switching module being housed in the casing. When the switching elements are turned on and off, the electric power converter module  60  converts the DC electric power from the battery  18  into the three-phase AC electric power, or converts three-phase AC electric power from the traction motor  28  into DC electric power. 
     The heat sink  50  and the upper case  52  jointly make up a charging device chamber  72  housing the quick charging device  62  therein, a fuse chamber  74  housing the fuses  98   a ,  98   b  therein, an electric power converter chamber  76  housing the electric power converter module  60  therein, and a three-phase terminal chamber  78  housing the three-phase terminals  64   a ,  64   b ,  64   c  therein. The charging device chamber  72  has a first opening  72   a  defined in the upper surface of the upper case  52  for providing access into the charging device chamber  72 . The fuse chamber  74  has a second opening  74   a  defined in the upper surface of the upper case  52  for providing access into the fuse chamber  74 . The electric power converter chamber  76  has a third opening  76   a  defined in the upper surface of the upper case  52  for providing access into the electric power converter chamber  76 . The three-phase terminal chamber  78  has a fourth opening  78   a  defined in the upper surface of the upper case  52  for providing access into the three-phase terminal chamber  78  (see  FIGS. 4, 8 ). The ECU (controller)  70  for controlling the electric power converter module  60  is disposed in the charging device chamber  72  above the quick charging device  62 . 
     The upper cover  54  has a first upper cover  54   a  covering the first opening  72   a , a second upper cover  54   b  covering the second opening  74   a , a third upper cover  54   c  covering the third opening  76   a , and a fourth upper cover  54   d  covering the fourth opening  78   a . The charging device chamber  72  is higher than the fuse chamber  74 , the electric power converter chamber  76 , and the three-phase terminal chamber  78 . Therefore, the first opening  72   a  is in a position higher than the second through fourth openings  74   a  through  78   a.    
     A capacitor module  80  having a smoothing capacitor  96  (see  FIG. 7 ) is suspended from an inner wall surface of the upper case  52  above the electric power converter module  60  and below the third opening  76   a . The smoothing capacitor  96 , which is electrically connected to the electric power converter module  60 , serves to smooth electric power from the battery  18 . The capacitor module  80  includes a housing that houses the smoothing capacitor  96 . 
     The lower case  56  has a bottom surface on which there are disposed a charger  82  for charging the battery  18  and a DC/DC converter  84  for stepping down the voltage of the battery  18  to supply low-voltage electric power to devices (electric components) of a low-voltage system on the electric vehicle  10 . The DC/DC converter  84  and the charger  82  are housed in respective rectangular housings. The charger  82  has more parts than the DC/DC converter  84 , and thus tends to be large in size. Thus, the housing that houses the charger  82  is larger than the housing that houses the DC/DC converter  84 . 
     The heat sink  50  has an inlet port  86  through which a fluid flows in and an outlet port  88  through which a fluid flows out. A bottom surface of the heat sink  50  and an upper surface of the lower case  56  jointly define a fluid channel, not shown, through which the fluid flows. The fluid that has flowed in through the inlet port  86  flows through the fluid channel defined by the heat sink  50  and the lower case  56  and flows out of the outlet port  88 . The heat sink  50  thus dissipates heat generated by the electric power converter module  60 , and the quick charging device  62 , etc. on the upper surface of the heat sink  50 , and the charger  82  and the DC/DC converter  84  on the bottom surface of the heat sink  50 , thereby cooling these components. 
       FIG. 5  is a top plan view of the heat sink  50 ,  FIG. 6  is a bottom plan view of the lower case  56 , and  FIG. 7  is a circuit diagram of the power control unit  30 . 
     The electric power converter module  60  is connected to the power supply connectors  94  (see  FIG. 7 ), and the battery  18  is connected to the power supply connectors  94  by the power supply cables  34 , thus connecting the electric power converter module  60  to the battery  18 . The smoothing capacitor  96  of the capacitor module  80  for smoothing the applied voltage is connected in parallel between the electric power converter module  60  and the battery  18 . The capacitor module  80  is electrically connected to the DC/DC converter  84 , the charger  82 , the quick charging device  62 , and the fuses  98   a ,  98   b  by bus bars. 
     The DC/DC converter  84 , the charger  82 , the quick charging device  62 , and the fuses  98   a ,  98   b  are thus connected to the battery  18 . The bus bars can be blanked out of a metal sheet such as a copper sheet or the like. The quick charging device  62  has a diode (quick charging diode)  100 , a first main contactor (first quick charging contactor)  102 , a second main contactor (second quick charging contactor)  104 , a resistor R, and a pre-contactor  106 . Since the high-voltage components (the electric power converter module  60 , the DC/DC converter  84 , the charger  82 , and the quick charging device  62 ) are housed in one casing, they can be connected by the bus bars without using high-voltage cables, so that the power control unit  30  can be reduced in size and hence in cost. 
     As shown in  FIG. 5 , the capacitor module  80  has a first positive terminal  110   a , a first negative terminal  110   b , a second positive terminal  112   a , a second negative terminal  112   b , a third positive terminal  114   a , and a third negative terminal  114   b . The first positive terminal  110   a , the second positive terminal  112   a , and the third positive terminal  114   a  are held in electrical conduction with each other, whereas the first negative terminal  110   b , the second negative terminal  112   b , and the third negative terminal  114   b  are held in electrical conduction with each other. The second positive terminal  112   a  and the second negative terminal  112   b  are connected to the power supply connectors  94  by respective bus bars  115   a ,  115   b  and respective power supply cables  94   a ,  94   b  (see  FIG. 6 ). Therefore, the second positive terminal  112   a  is connected to the positive pole of the battery  18 , whereas the second negative terminal  112   b  is connected to the negative pole of the battery  18 . 
     The electric power converter module  60  has a positive connection terminal and a negative connection terminal (connection terminals), not shown, that are connected respectively to the second positive terminal  112   a  and the second negative terminal  112   b . The positive connection terminal of the electric power converter module  60  is connected to the second positive terminal  112   a  and an end of the bus bar  115   a , whereas the negative connection terminal of the electric power converter module  60  is connected to the second negative terminal  112   b  and an end of the bus bar  115   b . The power supply cables  94   a ,  94   b  are inserted from below the heat sink  50  through respective through holes  50   a ,  50   b  into the power control unit  30  where the power supply cables  94   a ,  94   b  are connected to the other ends of the bus bars  115   a ,  115   b , respectively. 
     The first positive terminal  110   a , ends of the fuses  98   a ,  98   b , and the cathode of the diode  100  are connected to each other by a single bus bar  116 , so that the bus bar  116  and the battery  18  have the same potential. The other end of the fuse  98   a , which is not connected to the first positive terminal  110   a , is connected to an air conditioner compressor (compressor for air conditioner)  118 , and the other end of the fuse  98   b , which is not connected to the first positive terminal  110   a , is connected to a heater  120  (see  FIG. 7 ). 
     The cathode of the diode  100  is connected to an end of the first main contactor  102  through the resistor R and the pre-contactor  106 . The anode of the diode  100  is connected to the end of the first main contactor  102  by a bus bar  122 . The first negative terminal  110   b  is connected to an end of the second main contactor  104  by a bus bar  124 . 
     As shown in  FIGS. 5 and 6 , the third positive terminal  114   a  is connected to a fourth positive terminal  130   a  of the charger  82  by bus bars  126 ,  128  and is also connected to a fifth positive terminal  134   a  of the DC/DC converter  84  by the bus bar  126  and a bus bar  132 . The third negative terminal  114   b  is connected to a fourth negative terminal  130   b  of the charger  82  by bus bars  136 ,  138  and is also connected to a fifth negative terminal  134   b  of the DC/DC converter  84  by the bus bar  136  and a bus bar  140 . 
     The charger  82  has a sixth positive terminal  142   a  and a sixth negative terminal  142   b  that are connected to a connector  92  by cables  92   a . The DC/DC converter  84  has a seventh positive terminal  144   a  and a seventh negative terminal  144   b  that are connected to cables  146  extending out of the power control unit  30 . Electric power having voltage stepped down by the DC/DC converter  84  can be supplied to the devices of the low-voltage system on the electric vehicle  10  by the cables  146 . 
     As shown in  FIG. 6 , the DC/DC converter  84  and the charger  82  are arranged with their longitudinal axes extending perpendicularly to each other. A long side of the DC/DC converter  84  is adjacent to a short side of the charger  82 . 
     When a plug  93  connected to the connector  92  is coupled to a commercial electric power outlet, 100-V or 200-V AC electric power is supplied to the charger  82 , which charges the battery  18  normally (see  FIG. 7 ). 
       FIG. 8  is a top plan view of the heat sink  50  shown in  FIG. 5  with the upper case  52  disposed on an upper portion thereof. In  FIG. 8 , the capacitor module  80  is omitted from illustration. The upper case  52  has quick charging connectors  148  which are connected respectively to the other end of the first main contactor  102  and the other end of the second main contactor  104  by respective bus bars  149   a ,  149   b . To the quick charging connectors  148 , there is connected a connector  152  that can be connected to a charger connector  150  of a quick charger, not shown, for supplying high-voltage DC electric power, which is installed in a service area or a charging station (see  FIG. 7 ). When the charger connector  150  of the quick charger is connected to the connector  152 , the quick charger charges the battery  18  quickly. 
       FIG. 9  illustrates the manner in which the ECU  70  is installed in the charging device chamber  72 .  FIG. 10  shows in fragmentary cross section the power control unit  30  with the ECU  70  installed therein. The charging device chamber  72  is surrounded by a peripheral wall  160  that is made up of an outer peripheral wall  162  of the upper case  52 , a partition wall  164  separating the charging device chamber  72  and the fuse chamber  74  from each other, and a partition wall  166  separating the charging device chamber  72  and the electric power converter chamber  76  from each other. At least a portion of the partition walls  164 ,  166  performs a function as an outer wall of the upper case  52 , and is made of metal such as aluminum or the like. As the ECU  70  is mounted on the peripheral wall  160  of the charging device chamber  72  which is disposed in a position higher than the electric power converter chamber  76 , the ECU  70  is disposed in a position above the quick charging device  62  and surrounded by the peripheral wall  160 . In installation of the ECU  70  in the charging device chamber  72 , fastening portions  172 ,  172  (see  FIG. 8 ) on the partition wall  166  and on the outer peripheral wall  162 , which faces the partition wall  166 , of the upper case  52  and fastening portions  174 ,  174  of the ECU  70  are fastened to each other by screws  170 ,  170  whereby the ECU  70  is installed in the charging device chamber  72 . 
     As shown in  FIG. 10 , inasmuch as the partition wall  166  is disposed between the ECU  70  and the electric power converter module  60 , noise from the electric power converter module  60  is blocked by the partition wall  166  which is made of metal such as aluminum or the like. Therefore, the adverse effect of noise caused by the electric power converter module  60  on the ECU  70  can be reduced. Even though the ECU  70  is disposed above the quick charging device  62 , since the quick charging device  62  does not charge the battery  18  while the electric vehicle  10  is traveling, i.e., while the ECU  70  is energizing the traction motor  28 , the quick charging device  62  does not produce noise while the ECU  70  is in operation, and hence the ECU  70  is not adversely affected by noise from the quick charging device  62 . On the other hand, while the quick charging is being performed, the electric vehicle  10  does not travel (i.e., the ECU  70  is not in operation). Thus, there is no need to worry about noise from the quick charging device  62 . 
     As described above, the power control unit  30  has the electric power converter chamber  76  housing the electric power converter module  60  therein and the charging device chamber  72  housing the quick charging device  62  therein, and the ECU  70  is disposed in a position above the quick charging device  62  and surrounded by the peripheral wall  160  which includes the partition wall  166  that separates the charging device chamber  72  and the electric power converter chamber  76  from each other. Consequently, noise from the electric power converter module  60  is blocked by the partition wall  166 . Therefore, the adverse effect that noise from the electric power converter module  60  may otherwise have on the ECU  70  can be reduced. Since the quick charging device  62  does not operate while the ECU  70  is in operation, the ECU  70  is not adversely affected by noise from the quick charging device  62 . On the other hand, while the quick charging device is in use, the quick charging device  62  produces noise. However, as the ECU  70  is not in operation, there is no need to worry about noise from the quick charging device  62 . 
     The charging device chamber  72  has the first opening  72   a , the fuse chamber  74  has the second opening  74   a , the electric power converter chamber  76  has the third opening  76   a , and the three-phase terminal chamber  78  has the fourth opening  78   a . Therefore, the components in these chambers have improved maintainability and can easily be serviced for maintenance. 
     Furthermore, as the charging device chamber  72  is positioned higher than the electric power converter chamber  76 , and the ECU  70  is mouthed on the partition wall  166  of the charging device chamber  72  that is positioned higher than the electric power converter chamber  76 , the partition wall  166  effectively blocks noise from the electric power converter module  60 , so that the adverse effect that noise from the electric power converter module  60  may otherwise have on the ECU  70  can be further reduced. 
     Although the preferred embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the scope of the above embodiment. It is obvious to those skilled in the art that various changes or improvements can be made to the above embodiment. It is apparent from the scope of the claims that those changes and improvements will be included in the technical scope of the present invention.