Abstract:
Provided are an electric vehicle and a vehicle power feeding method capable of charging, at an ultra-high speed, an electricity storage device of the electric vehicle that travels on a trackless road. A control device of the electric vehicle executes a first charging control for controlling a voltage converter to limit the input current from a power feeding portion to an electricity storage device or the variation of the input current per unit time and allowing the voltage converter to charge the electricity storage device; and a second charging control for, for example, slopping the transforming operation of the voltage converter and allowing the voltage converter to charge the electricity storage device. Both charging controls are executed while moving the contact point between an electrical connection portion and the power feeding portion, and the execution time of the second charging control is longer than that of die first charging control.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an electric vehicle that travels on a trackless trajectory and a vehicle power supplying (feeding) method in which the electric vehicle is used. More specifically, the present invention relates to an electric vehicle and a vehicle power supplying method in which the electric vehicle is used, which are capable of supplying power at ultra-high-speed by bringing an energizing arm into contact with external power lines during traveling. 
       BACKGROUND ART 
       [0002]    Heretofore, as charging methods for an electric vehicle, there have been known contact type charging for charging an electric vehicle by having a charging nozzle connect to the electric vehicle while the electric vehicle is stopped, and non-contact charging for charging the electric vehicle through magnetic forces in a non-contact state. 
         [0003]    In the former method, even in the case of a comparatively fast rapid charging system, with currently installed charging devices, time on the order of thirty minutes is required until the electric vehicle becomes fully charged, and the usefulness of such charging devices is low in comparison with gasoline-powered vehicles. 
         [0004]    Although the latter non-contact charging method carries out charging through magnetic forces, problems have existed in that the charging power is lower as the influence of magnetic forces on the exterior must be taken into consideration, or investment costs in infrastructure become high due to complexity of the technology and equipment. 
         [0005]    Notwithstanding, practical use of an electric vehicle is urgently needed from the standpoint of environmental issues, and there has been a demand to develop at an early stage an electric vehicle having the same level of convenience as a gasoline-powered vehicle. 
         [0006]    Thus, as disclosed in Japanese Laid-open Patent Publication No. 2006-246568 and Japanese Laid-open Patent Publication No. 2001-128304, in order to enhance the convenience of the electric vehicle, techniques have been proposed for charging during traveling of the vehicle. However, all of these techniques are in a conceptual phase, and heretofore none of them have actually been studied deeply and embodied in detailed form. 
         [0007]    Further, as techniques that are comparatively close from the standpoint of enabling charging during traveling and for which progress is notable, techniques for hybrid (electric) trains exist, as disclosed in Japanese Laid-open Patent Publication No. 2008-263741 and Japanese Laid-open Patent Publication No. 2009-171772. In such techniques, a vehicle or a train that travels on a track travels along an electrified section and a non-electrified section. In addition, within the electrified section, charging of a vehicle-mounted energy storage device is carried out while the vehicle is traveling with electrical power from aerial power lines, whereas within the non-electrified section, the vehicle travels with charged power from the energy storage device. 
         [0008]    However, in the case that the vehicle is traveling on a track, the electrified section is constructed on the assumption that traveling of the vehicle occurs at a predetermined vehicle speed roughly from the beginning to the end thereof. Therefore, in order to enable full charging of the energy storage device within the electrified section, in accordance therewith, the lengths of the electrified section and the non-electrified section, and the charging speed should be set appropriately. 
         [0009]    However, the charging time is not assured under an environment such as when traveling takes place on a trackless trajectory, in which the vehicle speed within the electrified section and contact with and separation away from the power lines are controlled in accordance with the intentions of the driver. Therefore, the ideas differ fundamentally, and it has not been possible to simply put to use the technology of hybrid trains. 
         [0010]    In view of this situation, the present applicant has proposed the technique disclosed in Japanese Laid-Open Patent Publication No. 2013-208008 (hereinafter referred to as “JP2013-208008A”). With the power supplying control of JP2013-208008A (see  FIGS. 4 through 6 ), prior to a power receiving arm AM coming into contact with power line contact terminals CT, i.e., “II: immediately before supply of power”, a pre-charging process is carried out. Further, after the power receiving arm AM has contacted the power line contact terminals CT, i.e., upon “III: initial of supply of power”, a current that flows in a high voltage battery  24  (battery current Ib) is controlled so as to increase gradually. Thereafter, i.e., upon “IV: supply of power”, an external power supplying portion  12  and the high voltage battery  24  are directly connected to each other. 
       SUMMARY OF INVENTION 
       [0011]    As noted above, according to JP 2013-208008A, the control is changed by being divided into “II: immediately before supply of power”, “III: initial supply of power”, and “IV: supply of power” states. According to JP2013-208008A, during charging, a current increasing section (“III: initial supply of power”) during which the battery current lb is limited cakes a long time (see  FIG. 6 ). Therefore, the charging time is still long, and responsive thereto, since the aerial line section must also be long, problems have occurred in putting this technique into practice. 
         [0012]    The present invention has been devised taking into consideration the aforementioned problems, and has the object of providing an electric vehicle and a vehicle power supplying method in which the electric vehicle is used, which are capable of charging at ultra-high-speed an energy storage device of the electric vehicle that travels on a trackless trajectory. 
         [0013]    An electric vehicle according to the present invention travels on a trackless trajectory, wherein the electric vehicle comprises a traction motor, an energy storage device configured to supply electrical power to the traction motor, an energizing portion configured to come into contact with a power supplying portion and to connect electrically between the power supplying portion and the energy storage device, a voltage converter configured to adjust supply of electrical power to the energy storage device from the power supplying portion via the energizing portion, and a control unit configured to control the voltage converter. The control unit is configured to carry out a first charging control to charge the energy storage device by controlling the voltage converter so as to control an input current or an amount of change per unit time of the input current from the power supplying portion to the energy storage device, and a second charging control to charge the energy storage device with electrical power from the power supplying portion in which a converting operation of the voltage converter is stopped and voltage conversion is not carried out, or to charge the energy storage device by controlling the voltage converter on a basis of a target electrical power which is a target value of electrical power supplied to the energy storage device. Furthermore, the control unit is configured to implement the first charging control and the second charging control while a point of contact between the energizing portion and the power supplying portion is moved, implement the first charging control when the energizing portion comes into contact with the power supplying portion, and implement the second charging control after the first charging control, and for a period of time longer than that of the first charging control. 
         [0014]    According to the present invention, when the energizing portion contacts the power supplying portion. the first charging control is carried out in which the input current to the energy storage device (including an amount of charge per unit time thereof) is treated as the control object. Owing thereto, an instantaneous surge current at the time that energizing is started can be prevented, and welding or fusion between the power supplying portion and the energizing portion, or damage to the electrical circuitry on the side of the power supplying portion or on the side of the energizing portion can be prevented. Further, after the first charging control, the second charging control, which implements supply of power without voltage conversion or implements supply of power using the target electrical power (more specifically, supply of power in which the input current and the input voltage to the energy storage device are not directly limited), is carried out for a longer time period than that of the first charging control. Accordingly, charging over a very short time is enabled by a combination of the first charging control and the second charging control. 
         [0015]    Furthermore, under a control environment ranging from the first charging control to the second charging control, by bringing the power supplying portion and the energizing portion into contact while the contact point therebetween is moved, generation of heat at the contact point is not concentrated in one location. Consequently, even if a high current is energized in the second charging control, which is performed longer than the first charging control, welding or fusion between the power supplying portion and the energizing portion, or damage to the electrical circuitry on the side of the power supplying portion or on the side of the energizing portion can be prevented. 
         [0016]    Further still, because charging can be performed in an extremely short time period by the first charging control and the second charging control, charging of the energy storage device can be carried out reliably, even in situations that have been problematic in the case of traveling on a trackless trajectory, in which, according to the driver&#39;s intention, the contact position with the power supplying portion and the separation position from the power supplying portion are changed, and further, in which the charging time period is unpredictable due to the power supplying section, which is defined by the power supplying portion, being traveled through at high speed. 
         [0017]    In addition, since charging can be performed in a very short time period, the installation distance between and the number of power supplying sections can be kept to a minimum, and investment costs in infrastructure can be reduced. 
         [0018]    When an input voltage to the energy storage device during the second charging control arrives at a fully charged voltage of the energy storage device, the control unit may implement a third charging control to operate the voltage converter so as to maintain the input voltage at the fully charged voltage. Owing thereto, the energy storage device can be fully charged more reliably. 
         [0019]    Roller-shaped terminals that contact the power supplying portion may be formed on a distal end of the energizing portion. By this feature, damage to the contact site of the energizing portion with respect to the power supplying portion can be lightened or alleviated. 
         [0020]    The electric vehicle may comprise an aim displacement mechanism that causes the energizing portion to project out laterally of a vehicle body during traveling. Owing thereto, since it is possible for the power supplying portion to be disposed laterally of the travel path, installation of the power supplying portion can be performed at low cost. More specifically, compared to a case in which the power supplying portion is arranged upwardly of the vehicle body, since it is possible to dispose the power supplying portion at a lower position, it is possible to simplify equipment for supporting the power supplying portion. Further, although it is necessary to embed the power supplying portion in the travel path in the case that the power supplying portion is arranged below the vehicle body, in the case that the power supplying portion is arranged to the side of the travel path, there is no need to embed the power supplying portion in the travel path. Therefore, it is possible for the power supplying portion to be arranged with ease. 
         [0021]    A vehicle power supplying method according to the present invention charges an energy storage device of an electric vehicle by electrical power from an external power supplying apparatus in a state in which an energizing portion of the electric vehicle is placed in contact with respect to a power supplying portion of the external power supplying apparatus, wherein the electric vehicle travels on a trackless trajectory. In the electric vehicle, there are carried out a first charging control to charge the energy storage device by controlling a voltage converter so as to control an input current or an amount of change per unit time of the input current from the power supplying portion to the energy storage device, and a second charging control to charge the energy storage device with electrical power from the power supplying portion in which a converting operation of the voltage converter is stopped and voltage conversion is net carried out, or to charge the energy storage device by controlling the voltage converter on a basis of a target electrical power value which is a target value of electrical power supplied to the energy storage device. Furthermore, in the electric vehicle, the first charging control and the second charging control are implemented while a point of contact between the energizing portion and the power supplying portion is moved, the first charging control is implemented when the energizing portion comes into contact with the power supplying portion, and the second charging control is implemented after the first charging control. The power supplying portion is capable of initiating contact with the energizing portion and separating away therefrom at arbitrary positions, and when the energizing portion is placed in contact with the power supplying portion, under a condition in which a remaining capacity of the energy storage device is a predetermined value, and a vehicle speed of the electric vehicle or a movement speed of the power supplying portion is an assumed speed or lies within an assumed speed range, the first charging control and the second charging control are completed within a range that is shorter than half a total length of the power supplying portion, and together therewith, implementation time of the second charging control is longer than that of the first charging control. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0022]      FIG. 1  is an outline schematic view of a charging system equipped with an electric vehicle according to an embodiment of the present invention; 
           [0023]      FIG. 2  is a plan view showing with emphasis portions of the charging system in the embodiment; 
           [0024]      FIG. 3  is a front view showing with emphasis portions of the charging system in the embodiment; 
           [0025]      FIG. 4  is an external view showing schematically a portion of an external power supplying apparatus in the embodiment; 
           [0026]      FIG. 5  is a flowchart of an energizing arm control in the embodiment; 
           [0027]      FIG. 6  is a flowchart of a power receiving control by the electric vehicle in the embodiment; 
           [0028]      FIG. 7  is a view showing an example of an inter-terminal voltage of a battery and an input/output current in the case that the process of the flowchart of  FIG. 6  is carried out; 
           [0029]      FIG. 8  is a flowchart of a current limiting control (details of step S 13  of  FIG. 6 ); 
           [0030]      FIG. 9  is a flowchart of a target voltage control (details of step S 17  of  FIG. 6 ); 
           [0031]      FIG. 10  is an outline schematic view of a charging system equipped with an electric vehicle according to a modification of the present invention; and 
           [0032]      FIG. 11  is a flowchart of a target power control. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     I. Embodiment 
     1A. Configuration 
     [1A-1. Overall Configuration] 
       [0033]      FIG. 1  is an outline schematic view of a charging system  10  equipped with an electric vehicle  12  according to act embodiment of the present invention.  FIG. 2  is a plan view showing with emphasis portions of the charging system  10 .  FIG. 3  is a front view showing with emphasis portions of the charging system  10 . As shown in  FIGS. 1 through 3 , the charging system  10 , in addition to the electric vehicle  12  (hereinafter also referred to as a “vehicle  12 ”), includes an external power supplying apparatus  14  (hereinafter also referred to as a “power supplying apparatus  14 ”). Any of the directions (“front”, “rear”, “left”, “right”, “up”, “down”) in  FIGS. 2 and 3  are directions on the basis of the vehicle  12  (the same holds true for  FIG. 4 ). 
         [0034]    According to the present embodiment, electrical power is supplied to the vehicle  12  from the power supplying apparatus  14 , and charging of a battery  24  (see  FIG. 1 ) for traveling of the vehicle  12  is performed. Conversely, electrical power may be supplied from the vehicle  12  to an external device (power supplying apparatus  14 , etc.). 
       [1A-2. Electric Vehicle  12 ] 
     (1A-2-1. Overall Configuration of Electric Vehicle  12 ) 
       [0035]    As shown in  FIGS. 1 through 3 , the vehicle  12  includes a traction motor  20  (hereinafter also referred to as a “motor  20 ”), an inverter  22 , a battery  24  for traveling (hereinafter also referred to as a “battery  24 ”), an energizing arm  26 , a DC/DC converter  28 , capacitors  30 ,  32 , voltage sensors  34 ,  36 ,  38 ,  40 , current sensors  42 ,  44 , an SOC sensor  46 , an arm deployment mechanism  48  (hereinafter also referred to as a “deployment mechanism  48 ”), an arm deployment swatch  50 , and an energizing electronic control unit  52  (hereinafter referred to as an “energizing ECU  52 ” or an “ECU  52 ”). 
         [0036]    The vehicle  12  travels on a trackless trajectory. Stated otherwise, the electric vehicle  12  differs from one that travels on a track such as a railway vehicle or the like, and the trajectory of the vehicle  12  is capable of being freely changed. 
       (1A-2-2. Traction Motor  20 ) 
       [0037]    The traction motor  20  is a 3-phase brushless type of motor, which generates a drive force F [N] (or a torque [N·m]) for the vehicle  12  on the basis of electrical, power supplied from the battery  24  through the inverter  22 . Further, the motor  20  carries out charging of the battery  24  by outputting to the battery  24  power (regenerative power Preg) [W] produced by performing a regenerative operation. The regenerative power Preg may also be output to a step-down converter, a low-voltage battery, and auxiliary devices, none of which are shown. 
       (1A-2-3. Inverter  22 ) 
       [0038]    The inverter  22  is constituted as a 3-phase full-bridge type, which converts a DC current from the battery  24  into a 3-phase AC current and supplies the same to the motor  20 , whereas accompanying a regenerative operation, supplies a DC current to the battery  24  following AC/DC conversion. 
       (1A-2-4. Battery  24 ) 
       [0039]    The battery  24  is an energy storage device (energy storage) including a plurality of battery cells, and for example, a lithium ion secondary battery, a nickel-metal hydride battery, or the like, can be used therefore. Alternatively, in place of the battery  24  or in addition to the battery  24 , an energy storage device such as a capacitor or the like can be used. A non-illustrated DC/DC converter nay be disposed between the inverter  22  and the battery  24 , and an output voltage from the battery  24  or an output voltage from the motor  20  may be stepped-up or stepped-down in voltage. 
       (1A-2-5. Energizing Arm  26 ) 
       [0040]    The energizing arm  25  (hereinafter also referred to as an “arm  26 ”) is a site (energizing portion) that is placed in contact with the power supplying apparatus  14  when the battery  24  is charged with electrical power from the power supplying apparatus  14 . As shown in  FIG. 2 , the energizing arm  26  is connected to a vehicle body  62  at a location between the front wheels Wf and the rear wheels Wr, with one end (fixed end) thereof being capable of rotating about an axis of rotation  60 . Therefore, the energizing arm  26  is capable of being deployed (or displaced) transversely or laterally of the vehicle  12  (on the right side in the present embodiment) at a time of contact with the power supplying apparatus  14 . 
         [0041]    An energizing head  70  including a power receiving portion  72  (energizing portion) and a contact sensor  74  is provided on a distal end of the energizing arm  26 . The power receiving portion  72  includes a positive electrode terminal  76   p  and a negative electrode terminal  76   n.  The positive electrode terminal  76   p  and the negative electrode terminal  76   n  are connected electrically with a fixed end side through non-illustrated conductive members. The positive electrode terminal  76   p  and the negative electrode terminal  76   n  of the present embodiment are shaped in the form of rollers (see  FIGS. 2 and 3 ). The vehicle  12  and the power supplying apparatus  14  are connected electrically by the power receiving portion  72  being placed in contact with external power lines  170  (power supplying portion or power supplying lines) of the power supplying apparatus  14 . 
         [0042]    The contact sensor  74  serves to detect contact between the energizing head  70  and the external power supplying apparatus  14  (later described external power lines  170 ), and is constituted, for example, from a pressure sensor disposed on a portion of the energizing head  70 . Alternatively, the contact sensor  74  may be constituted as a pressure sensor that is arranged between the power receiving portion  72  and the converter  28 . 
         [0043]    Concerning the principal structure of the energizing arm  26 , for example, the structure disclosed in Japanese Laid-open Patent Publication No. 2013-233037 can be used. 
       (1A-2-6. DC/DC Converter  28 ) 
       [0044]    The DC/DC converter  28  (hereinafter also referred to as a “converter  28 ” or a “vehicle side converter  28 ”) converts an output voltage of the power supplying apparatus  14  (hereinafter referred to as an “output voltage Vs” or a “power supply voltage Vs”) and outputs the same to the inverter  22  and the battery  24 . In addition, the converter  28  is capable of converting the output voltage from the battery  24  and supplying the output voltage from the battery  24  to the exterior (for example, the external power supplying apparatus  14 ) through the power receiving portion  12 . 
         [0045]    The converter  28  of the present embodiment steps-down the power supply voltage Vs and outputs the same to the side of the vehicle  12 , together with stepping-up the output voltage of the battery  24  and outputting the same to the exterior. However, the converter  28  may carry out only stepping-up of the power supply voltage Vs, or may carry-out both stepping-up and stepping-down in voltage thereof. 
         [0046]    As shown in  FIG. 1 , the converter  28  includes an upper arm  80 , a lower arm  82 , and a reactor S 4 . The upper arm  80  includes a switching element  86   u,  and a diode  88   u  that is disposed in a reverse parallel manner therewith. The lower arm  82  includes a switching element  86   l,  and a diode  38   l  that is disposed in a reverse parallel manner therewith. As the switching elements  86   u,    86   l,  there may be adopted power switching elements such as a MOSFET (including a SiC (silicon carbon) type of MOSFET) or an IGBT or the like. 
         [0047]    The switching element  86   u  is switched by a drive signal Su supplied from the ECU  52 , and the switching element  86   l  is switched by a drive signal Sl supplied from the ECU  52 . The drive signals Su, Sl are PWM (pulse width modulated) signals. 
         [0048]    In  FIG. 1 , although one each of the switching elements  86   u,    86   l  is illustrated, a configuration may be provided in which a plurality of switching elements are arranged in parallel, respectively. Stated otherwise, a plurality of switching elements  86   u,  which are arranged in parallel, and a plurality of switching elements  86   l,  which are arranged in parallel, may be provided. Further, in the case that a plurality of switching elements  86   u  are used, one or a plurality thereamong may be SiC type MOSFETs, whereas the remaining ones may be constituted by IGBTs. In accordance therewith, the rate of passage of the current is increased by the SiC type MOSFETs, and passage of a large current can be facilitated by the IGBTs. Similarly, the diodes  88   u,    88   l  also may be constituted from a plurality of diodes that are arranged in parallel. 
       (A-2-7. Capacitors  30 ,  32 ) 
       [0049]    The capacitor  30  is arranged between the power receiving portion  72  of the arm  26  and the converter  28 . The capacitor  32  is arranged between the converter  28  and branch points  90   p,    90   n.  The capacitors  30 ,  32 , for example, suppress voltage fluctuations by temporarily storing the electrical power from the power supplying apparatus  14 . 
       (1A-2-8. Voltage Sensors  34 ,  36 ,  38 ,  40 ) 
       [0050]    The voltage sensor  34  is arranged between the power receiving portion  72  and the DC/DC converter  23 , and detects a voltage (hereinafter referred to as a “converter input voltage Vc 1 ”, “a converter primary voltage Vc 1 ”, or a “primary voltage Vc 1 ”) on a primary side (input side) of the DC/DC converter  28 . The voltage sensor  36  is arranged between the DC/DC converter  28  and the branch points  90   p,    90   n,  and detects a voltage (hereinafter referred to as a “converter output voltage Vc 2 ”, “a converter secondary voltage Vc 2 ”, or a “secondary voltage Vc 2 ”) on a secondary side (output side) of the DC/DC converter  28 . 
         [0051]    The voltage sensor  38  is arranged between the battery  24  and the branch points  90   p,    90   n,  and detects an input/output voltage (hereinafter referred to as a “battery input/output voltage vbio”, an “input/output voltage vbio”, or a “voltage Vbio”) of the battery  24 . The voltage sensor  40  detects an inter-terminal voltage (hereinafter referred to as a “battery voltage vbat” or a “voltage Vbat”) of the battery  24 . 
       (1A-2-9. Current Sensors  42 ,  44 ) 
       [0052]    The current sensor  42  is arranged between the DC/DC converter  28  and the branch point  90   p,  and detects a current (hereinafter referred to as a “converter output current Ic 2 ”, “a converter secondary current Ic 2 ”, or a “secondary current Ic 2 ”) on the secondary side of the DC/DC converter  28 . The current sensor  44  is arranged between the battery  24  and the branch point  90   p,  and detects an input/output current (hereinafter referred to as a “battery input/output current Ibio”, an “input/output current Ibio”, or a “current Ibio”) of the battery  24 . 
       (1A-2-10. SOC Sensor  46 ) 
       [0053]    The SOC sensor  46  detects a remaining capacity (SOC: State of Charge) of the battery  24  and outputs the same to the ECU  52 . 
       (1A-2-11. Arm Deployment Mechanism  48  and Arm Deployment Switch  50 ) 
       [0054]    The arm deployment mechanism  46  serves to deploy the arm  26 , and as shown in  FIG. 2 , includes a slider unit  100  and a damper unit  102 . The slider unit  100  includes a slider  110  and a slider support member  112 . Based on a command from the ECU  52 , the slider  110  is capable of sliding with respect to the slider support member  112 . The slider  110 , for example, is an electromagnetic or a pneumatic type of linear actuator. 
         [0055]    One end (first end) of the damper unit  102  is connected rotatably to the slider  110 , and another end (second end) thereof is connected rotatably to the arm  26 . When the arm  26  is deployed, the slider  110  is displaced to the front side of the vehicle  12 , and the first end of the damper unit  102  is displaced forward. When the arm  26  is housed, the slider  110  is displaced to the rear side of the vehicle  12 , and the first end of the damper unit  102  is displaced rearward. 
         [0056]    The arm deployment switch  50  (hereinafter also referred to as a “switch  50 ”) serves to issue a command for deployment of the arm  26  in accordance with an operation from the user. The switch  50 , for example, is formed on a portion of the steering wheel (not shown). When the switch  50  is turned on, the arm  26  is deployed through the deployment mechanism  48 , and when the switch  50  is turned off, the arm  26  is accommodated through the deployment mechanism  48 . 
       (1A-2-12. ECU  52 ) 
       [0057]    The ECU  52  serves to control reception of inputs from respective components of the vehicle  12  or to control the respective components themselves through a vehicle side communications line  120  (see  FIG. 1 ), and includes an input/output unit  130 , a computation unit  132 , and a storage unit  134 . In the present embodiment, the computation unit  132  of the ECU  52  includes an arm controller  140  and an energizing controller  142 . The arm controller  140  controls the energizing arm  26  through the arm deployment mechanism  48 . The energizing controller  142  controls charging of the battery  24  or supply of power from the battery  24 . 
       [1A-3. External Power Supplying Apparatus  14 ] 
       [0058]      FIG. 4  is an external view showing schematically a portion of the external power supplying apparatus  14 . As shown in  FIGS. 1 through 4 , the power supplying apparatus  14  includes a DC power source  150 , a contact-type power supplying portion  152 , a DC/DC converter  154  (hereinafter also referred to as a “converter  154 ” or an “external converter  154 ”), a diode  156 , a voltage sensor  158 , an input device  160 , and a control device  162 . Hereinafter, the DC power source  150 , the converter  154 , the diode  156 , the voltage sensor  158 , the input device  160 , and the control, device  162  may also be referred to collectively as a voltage applying unit  164 . The voltage applying unit  164  is a site that applies a voltage with respect to the contact-type power supplying portion  152 . 
       (1A-3-1. DC Power Source  150 ) 
       [0059]    The DC power source  150  (hereinafter also referred to as a “power source  150 ”) supplies electrical power with respect to the vehicle  12 . The power source  150  of the present embodiment is constituted, for example, by connecting a plurality of batteries together in series. Alternatively, the power source  150  may be constituted from a single battery. Alternatively, the power source  150  can be constituted from a combination of a commercial AC power source and an AC/DC converter (not shown). 
       (1A-3-2. Contact-Type Power Supplying Portion  152 ) 
     (1A-3-2-1. Overall Configuration of Contact-Type Power Supplying Portion  152 ) 
       [0060]    The contact-type power supplying portion  152  (hereinafter also referred to as a “power supplying portion  152 ”) is a site, which by being placed in contact with the arm  26  of the vehicle  12 , supplies electrical power from the power source  150  to the side of the vehicle  12 . As shown in  FIGS. 1 through 4 , the contact-type power supplying portion  152  of the present embodiment includes the external power lines  170  (hereinafter also referred to as “power lines  170 ”), a power line retaining section  172 , and a plurality of support posts  174 . 
       (1A-3-2-2. External Power Lines  170 ) 
       [0061]    The external power lines  170  comprise a positive electrode terminal  180   p  and a negative electrode terminal  180   n.  As shown in  FIGS. 3 and 4 , the positive electrode terminal  180   p  and the negative electrode terminal  130   n  are formed in the interior of a groove member  182  that is formed in the power line retaining section  172 . Therefore, the external power lines  170  are constituted as aerial power lines that are disposed above a travel path  190  (see  FIGS. 2 and 3 ). Further, as shown in  FIG. 2 , the positive electrode terminal  180   p  and the negative electrode terminal  180   n  are arranged to the side of the travel path  190  along the travel path ISO of the vehicle  12 . In particular, the positive electrode terminal  180   p  and the negative electrode terminal  180   n  are disposed in the form of a straight line. The length (total length) of the positive electrode terminal  180   p  and the negative electrode terminal  180   n  in the direction of travel of the vehicle  12  can be set to any value, for example, within a range of 20 to 300 m. 
       (1A-3-2-3. Power Line Retaining Section  172  and Support Posts  174 ) 
       [0062]    As discussed above, the power line retaining section  172  retains external power lines  170  in the groove member  182  thereof. The support posts  174  are disposed vertically on the side of the travel path  190 , and support the external power lines  170  and the power line retaining section  172 . 
       (1A-3-3. External Converter  154 ) 
       [0063]    The external converter  154  converts the input voltage (power source voltage Vcc) from the power source  150 , and outputs the same to the external power lines  170 . The converter  154  is a step-up/step-down type converter. Alternatively, depending on the power source voltage Vcc, the converter  154  can be a step-up or a step-down type of converter. 
         [0064]    The conversion ratio of the converter  154  is controlled by the control device  162 . More specifically, the duty ratios of drive signals Sd with respect to the converter  154  is adjusted, whereby the power supply voltage Vs is controlled by converting the power source voltage Vcc. The power source voltage Vcc according to the present embodiment is a comparatively high voltage, and the converter  154  produces the power supply voltages Vs by stepping-down the power source voltage Vcc, Alternatively, the converter  154  may carry out only stepping-up of the power source voltage Vcc, or may carry out both stepping-up and stepping-down in voltage thereof. After the power supply voltage Vs has reached the target value, the control device  162  maintains the power supply voltage Vs at a constant value. 
       (1A-3-4. Diode  156 ) 
       [0065]    The diode  156  is arranged between the converter  154  and the positive electrode terminal  180   p,  and serves to prevent flowing of current from the vehicle  12  to the side of the power supplying apparatus  14 . 
       (1A-3-5. Voltage Sensor  153 ) 
       [0066]    The voltage sensor  158  is disposed on a secondary side (output side) of the DC/DC converter  154 , detects the output voltage Vs of the converter  154 , and outputs information thereof to the control device  162 . 
       (1A-3-6. Input Device  160 ) 
       [0067]    The input device  160  serves to input to the control device  162  commands from an administrator of the power supplying apparatus  14 . The input device  160  can be constituted, for example, from a plurality of operation buttons, and in input means such as a keyboard or the like. 
       (1A-3-7. Control Device  162 ) 
       [0068]    The control device  162  serves to control the power supplying apparatus  14  as a whole, and according to the present embodiment, primarily controls the external converter  154 . 
       1B. Various Types of Control 
     [1B-1. Overview] 
       [0069]    Next, a description will be presented concerning various controls when electrical power is supplied to the vehicle  12  from the power supplying apparatus  14 , and charging of the battery  24  of the vehicle  12  is performed. The controls include an energizing arm control and a charging control. 
         [0070]    The energizing arm control is a control for the energizing arm  26  prior to charging, during charging, and after charging of the battery  24 , which is implemented by the arm controller  140  of the ECU  52 . The charging control is a control for carrying out charging of the battery  24  of the vehicle  12 . In the charging control, there are included a power supplying control implemented by the control device  162  of the power supplying apparatus  14 , and a power receiving control implemented by the energizing controller  142  of the ECU  52  of the vehicle  12 . 
       [1B-2. Energizing Arm Control] 
       [0071]      FIG. 5  is a flowchart of the energizing arm control according to the present embodiment. In step S 1 , the ECU  52  determines whether or not a deployment starting condition for the energizing arm  26  has been satisfied. As such a deployment starting condition, there can be cited, for example, that the deployment switch  50  has been turned on. In addition to or in place thereof, the fact that a distance (distance in the direction of travel) between the vehicle  12  and the contact-type power supplying portion  152  in the direction of travel of the vehicle  12  is less than or equal to a predetermined threshold value (distance threshold value) may serve as a deployment starting condition. In order to determine the distance in the direction of travel, for example, there may be provided beforehand in the vehicle  12  a non-illustrated present position detecting device (for example, a navigation device), and a nap database in which position information of the power supplying apparatus  34  (contact-type power supplying portion  152 ) is stored. In addition, the distance in the direction of travel can be calculated as a distance between the present position of the vehicle  12  and the position of the contact-type power supplying portion  152 . 
         [0072]    Alternatively, it is possible to provide communications devices for short-range communications, respectively, in the vehicle  12  and the power supplying apparatus  14 , and it can be judged that the deployment starting condition is satisfied when communications between both communications devices are established. 
         [0073]    In the case that the deployment starting condition is not satisfied (step S 1 : NO), then the current process is terminated, and the procedure is started again from step Si after elapse of a predetermined time period. In the case that the deployment starting condition is satisfied (step S 1 : YES), then the routine proceeds to step S 2 . 
         [0074]    In step S 2 , the ECU  52  implements a deployment process for deploying the arm  26 , which is in an accommodated state. By the deployment process, the arm  26  is displaced to a position where it projects out maximally from the vehicle body  62  of the vehicle  12 . In this state, a distance Ls (see  FIG. 2 ) between the vehicle  12  and the contact-type power supplying portion  152  is adjusted by the driver steering the vehicle  12 , whereby the arm  26  approaches toward the external power lines  170 . 
         [0075]    In step S 3 , the ECU  52  determines whether or not a deployment ending condition for the energizing arm  26  has been satisfied. As such a deployment ending condition, there can be cited, for example, that the deployment switch  50  has been turned off. 
         [0076]    In addition to or in place thereof, completion of charging of the battery  24  may be used as the deployment ending condition. Completion of charging can be determined by the SOC having reached a predetermined threshold value (SOC threshold value), or by the battery voltage Vbat having reached a predetermined threshold value (battery voltage threshold value). 
         [0077]    Alternatively, it is possible to provide communications devices for short-range communications, respectively, in the vehicle  12  and the power supplying apparatus  14 , and after communications between both communications devices has been established, it can be judged that the deployment ending condition is satisfied when communications are cut off. 
         [0078]    If the deployment ending condition has not been satisfied (step S 3 : NO), then step S 3  is repeated. In the case that the deployment ending condition is satisfied (step S 3 : YES), then in step S 4 , the ECU  52  implements an accommodating process for accommodating the energizing arm  26 , which is in the deployed condition. Upon completion of the accommodating process, the procedure is started again from step SI after elapse of a predetermined time period. 
       [1B-3. Power Supplying Control of External Power Supplying Apparatus  14 ] 
       [0079]    The control device  162  of the external power supplying apparatus  14  places the external power lines  170  in a power supplying capable state, on the basis of a command from an administrator that is input through the input device  160 . More specifically, the control device  162  outputs drive signals Sd (see  FIG. 1 ) intermittently or continuously to the switching element (not shown) of the external converter  154 , thereby connecting the power source  150  and the power lines  170 . Consequently, the power lines  170  are placed in a power supply enabling state. In addition, when the power receiving portion  72  of the arm  26  comes into contact with the power lines  170 , supply of power from the power supplying apparatus  14  to the vehicle  12  is carried out through the power lines  170 . 
       [1B-4. Power Receiving Control of Vehicle 12] 
     (1B-4-1. Overall Process Flow of Power Receiving Control) 
       [0080]      FIG. 6  is a flowchart of a power receiving control of the vehicle  12  according to the present embodiment.  FIG. 7  is a view showing an example of the inter-terminal voltage Vbat and the input/output current Ibio of the battery  24  in the case that the process of the flowchart of  FIG. 6  is carried Gut. The control of  FIG. 6  is carried out when the arm  26  is deployed. For example, the ECU  52  initiates the power receiving control with pressing of the deployment switch  50  being treated as a triggering event. 
         [0081]    In step S 11  of  FIG. 6 , the ECU  52  carries out a pre-charging process for raising the primary voltage Vc 1  of the converter  28  up to a threshold value (primary voltage threshold value THvc 1 ). More specifically, the ECU  52  turns on the switching element  86   l  in a state in which the switching element  86   u  is turned off, and accumulates in the reactor  84  electrical power from the battery  24 . Thereafter, the ECU  52  turns on the switching element  86   u  in a state in which the switching element  86   l  is turned off, and charges the capacitor  30  to raise the primary voltage Vc 1 . 
         [0082]    In step S 12 , the ECU  52  determines whether or not the power receiving portion  72  of the arm  26  has been placed in contact with the power supplying portion  152  of the power supplying apparatus  14 . Such a determination is carried out based on the output from the contact sensor  74 . 
         [0083]    If the power receiving portion  72  is not in contact with the power supplying portion  152  (step S 12 : NO), step  312  is repeated. If the power receiving portion  72  is in contact with the power supplying portion  152  (step S 12 : YES), then the routine proceeds to step S 13 . 
         [0084]    In step S 13 , the ECU  52  implements (at times t 1  to t 2  of  FIG. 7 ) the current limiting control for limiting the input/output current Ibio (in this case particularly, the input current) to the battery  24 . The current limiting control will be described later with reference to  FIG. 8 . 
         [0085]    In step S 14 , the ECU  52  determines whether or net the battery input/output voltage Vbio (in this case particularly, an input voltage (charging voltage)) has become greater than or equal to a threshold value (hereinafter referred to as a “first charging voltage threshold value THvchg 1 ” or a “first threshold value THvchg 1 ”). The threshold voltage THvchg 1  is a threshold value for determining whether or not a voltage difference between the output voltage Vs from the power supplying apparatus  14  and the voltage (primary voltage Vc 1 ) on the side of the vehicle  12  has become sufficiently small to reduce the inrush current to the vehicle  12  from the power supplying apparatus  14 . The threshold value THvchg 1  is set to a value that is lower than a fully charged voltage THvbatfull of the battery  24 . 
         [0086]    With such a determination, it should be borne in mind that the input direction to the battery  24  is made positive, the output direction from the battery  24  is made negative, and it is also possible to define the negative and positive values oppositely (the same holds true for other determinations). If the voltage Vbio is less than the threshold value THvchg 1  (step S 14 : NO), step S 13  is returned to, and the current limiting control is continued. If the voltage Vbio is greater than or equal to the threshold value THvchg 1  (step S 14 : YES), then the current limiting control is brought to an end, and the routine proceeds to step S 15 . 
         [0087]    In the determination of step S 14 , instead of comparing the battery input/output voltage Vbio and the threshold value THvchg 1 , the battery input/output current Ibio may be compared with a threshold value therefore (an input current threshold value THichg 1 ). The current threshold value THichg 1  is a threshold value for ensuring that the current that is input to the battery  24  (the current Ibio or the current Ic 2 ) does not become an inrush current. 
         [0088]    In step S 15 , the ECU  52  stops the converting operation by the converter  28 , and implements a direct connection control for directly supplying electrical power from the power supplying apparatus  14  to the battery  24 , etc. (at times t 2  to t 3  of  FIG. 7 ). In this case, the ECU  52  continuously outputs (i.e., at a duty ratio of 100%) a drive signal Su with respect to the switching element  86   u  of the converter  28 . The direct connection control is a control (voltage and current unlimited control) in which a combination of the battery input/output voltage Vbio and the battery input/output current Ibio (or a combination of the output voltage Vc 2  and the output current Ic 2  of the converter  28 ) is not treated as a direct control object. 
         [0089]    With the direct connection control, the output voltage Vs of the power supplying portion  152  is applied to the battery  24  in the absence of the converting operation of the converter  28 . Along therewith, the battery voltage Vbat rises gradually, whereas the battery input/output current Ibio decreases (at times t 2  to t 3  of  FIG. 7 ). 
         [0090]    In step S 16 , the ECU  52  determines whether or not the voltage Vbio has become greater than or equal to the fully charged voltage THvbatfull of the battery  24 . If the voltage Vbio is less than the fully charged voltage THvbatfull (step S 16 : NO), step S 15  is returned to, and the direct connection control is continued. If the voltage vbio is greater than or equal to the fully charged voltage THvbatfull (step S 16 : YES), then the direct connection control is brought to an end, and the routine proceeds to step S 17 . 
         [0091]    In step S 17 , the ECU  52  implements a target voltage control for matching the battery input/output voltage Vbio with a target value (hereinafter referred to as a “target voltage Vbiotar”) (at times t 3  to t 4  of  FIG. 7 ). with the target voltage control, the target voltage Vbiotar is set to the fully charged voltage THvbatfull of the battery  24 . More specifically, the ECU  52  sets a duty ratio of the converter  28  so that the voltage Vbio after being converted by the converter  28  becomes the fully charged voltage THvbatfull. Owing thereto, the battery voltage vbat rises gently toward the fully charged voltage THvbatfull, whereas the battery input/output current Ibio decreases (at times t 3  to t 4  of  FIG. 7 ). 
         [0092]    In step S 18 , the ECU  52  determines whether or not the SOC of the battery  24  has become greater than or equal to a threshold value (hereinafter referred to as a “fully charged threshold value THsocfull” or a “threshold value THsocfull”). The threshold value THsocfull is a threshold value for SOC, indicative of the fact that the battery  24  is in a fully charged state. In step S 18 , instead of comparing the SOC with a threshold value, the voltage Vbio may he compared with the fully charged voltage THvbatfull. If the SOC is not greater than or equal to the threshold value THsocfull (step S 18 : NO), step S 17  is returned to, and the target voltage control is continued. If the SOC is greater than or equal to the threshold value THsocfull (step S 18 : YES), then the ECU  52  terminates the target voltage control and the current process is brought to an end. 
       (1B-4-2. Current Limiting Control) 
       [0093]      FIG. 8  is a flowchart of the current limiting control (details of step S 13  of  FIG. 6 ). According to the present embodiment, the implementation time of the current limiting control is significantly shorter than the implementation time of the direct connection control. Owing thereto, it is possible to realize ultra-high-speed charging of the vehicle  12 . The temporal relationship between the current limiting control and the direct connection control will be described in detail later. Hereinbelow, the parenthetical term “(current)” will be used to denote values in the current computation cycle, and the parenthetical term “(previous)” will be used to denote values in the previous computation cycle. 
         [0094]    In step S 21  of  FIG. 8 , the ECU  52  acquires the battery input/output current Ibio (current). 
         [0095]    In step S 22 , the ECU  52  calculates a current difference ΔIbio. The current difference ΔIbio is a difference between the battery input/output current Ibio (current) and the battery input/output current Ibio (previous). 
         [0096]    In step S 23 , the ECU  52  determines whether or not the current difference ΔIbio fails below a threshold value (hereinafter also referred to as a “current difference threshold value THΔibio” or a “threshold value THΔibio”). The threshold value THΔibio is a threshold value for ensuring that the current that is input to the battery  24  (the current Ibio or the current Ic 2 ) does not become an inrush current. 
         [0097]    In the present embodiment, the threshold value THΔibio is set to a value corresponding to 10 to 100 times (for example, 60 times or more) the discharge capacity Wb [Ah] as a specification of the battery  24 . For example, if the discharge capacity Wb of the battery  24  is 2 [Ah], the threshold value THΔibio is set to a value to realize 20 to 200 [Ah]. The threshold value THΔibio is set depending on the computation cycle performed according to the flowchart of  FIG. 8 . 
         [0098]    If the current difference ΔIbio falls below the threshold value THΔibio (step S 23 : YES), the rate of increase of the current Ibio has room to rise to a value equivalent to the threshold value THΔibio. Thus, in step S 24 , the ECU 52  increases an added value ΔDUTu of the duty ratio DUTu of the upper arm  80 . More specifically, a positive fixed value α is added to the added value ΔDUTu (previous) of the duty ratio DUTu in order to arrive at the added value ΔDUTu (current). Subsequently, in step S 28 , the ECU  52  calculates the duty ratio DUTu (current) by adding the added value ΔDUTu (current) to the duty ratio DUTu (previous). 
         [0099]    In step S 23 , if the current difference ΔIbio does not fall below the threshold value THΔibio (step S 23 : NO), then in step S 25 , the ECU  52  determines whether or not the current difference ΔIbio exceeds the threshold value THΔibio. The threshold value in step S 25  may be a different value that is greater than the threshold value in step S 23 . If the current difference ΔIbio exceeds the threshold value THΔibio (step S 25 : YES), the current Ibio is increasing abruptly more than necessary. Thus, in step S 26 , the ECU 52  decreases an added value ΔDUTu of the duty ratio DUTu of the upper arm  80 . More specifically, a positive fixed value β is subtracted from the added value ≢DUTu (previous) of the duty ratio DUTu in order to arrive at the added value ΔDUTu (current). 
         [0100]    On the other hand, if the current difference ΔIbio does not exceed the threshold value THΔibio (step S 25 : NO), the current difference ΔIbio is equivalent to the threshold value THΔibio, and the rate of increase of the current Ibio is appropriate. Thus, in step S 27 , the ECU  52  maintains the added value ΔDUTu. More specifically, the added value ΔDUTu (previous) is set to the added value ΔDUTu (current) without change. After steps S 26  and S 27  as well, in step S 28 , the ECU  52  calculates the duty ratio DUTu (current) by adding the added value ΔDUTu (current) to the duty ratio DUTu (previous). 
         [0101]    Subsequently, in step S 29 , the ECU  52  controls the upper arm  80  and the lower arm  82  on the basis of the duty ratio DUTu (current). Specifically, the drive signal Su in accordance with the duty ratio DUTu is output with respect to the switching element  86   u  of the upper arm  80 . Further, the value 100%−DUTu is calculated as the duty ratio DUTl (DUTl=100−DUTu) of the switching element  86   l,  and the drive signal Sl in accordance with the duty ratio DUTl is output with respect to the switching element  86   l  of the lower arm  82 . However, a dead time is included between the drive signals Su, Sl of both switching elements  86   u,    86   l.    
       (1B-4-3. Target Voltage Control) 
       [0102]      FIG. 9  is a flowchart of the target voltage control (details of step S 17  of  FIG. 6 ). In step S 31 , the ECU  52  acquires from the voltage sensor  38  the battery input/output voltage Vbio in the current computation cycle (control cycle). In step S 32 , the ECU  52  determines whether or not the voltage Vbio is equal to the fully charged voltage THvbatfull of the battery  24 . If the voltage Vbio equals the fully charged voltage THvbatfull (step S 32 : YES), then in step S 33 , the ECU  52  maintains the conversion ratio Rcon of the converter  28 . If the voltage Vbio is not equal to the fully charged voltage THvbatfull (step S 32 : NO), the routine proceeds to step S 34 . 
         [0103]    In step S 34 , the ECU  52  determines whether or not the fully voltage Vbio falls below the fully charged voltage THvbatfull. If the voltage Vbio falls below the fully charged voltage THvbatfull (step S 34 : YES), then in step S 35 , the ECU  52  changes the conversion ratio Rcon of the converter  28  so as to increase the input/output voltage Vbio. For example, in the case of a step-down in voltage, when the duty ratio DUTu of the switching element  86   u  of the upper arm  80  is made greater, the voltage step-down ratio becomes smaller, and when the duty ratio DUTu is made smaller, the voltage step-down ratio becomes greater. 
         [0104]    If the voltage Vbio does not fall below the fully charged voltage THvbatfull (step S 34 : NO), the voltage Vbio exceeds the fully charged voltage THvbatfull (Vbio&gt;THvbatfull). In this case, in step S 36 , the ECU  52  changes the conversion ratio Rcon of the converter  28  so as to decrease the input/output voltage Vbio. 
         [0000]    (1B-4-4. Temporal Relationship Between Current Limiting Control, and Direct. Connection Control) 
         [0105]    Below, a description will be given of the temporal relationship between the current limiting control and the direct connection control. As noted above, according to the present embodiment, the implementation time of the current limiting control is significantly shorter than the implementation time of the direct connection control, whereby ultra-high-speed charging of the vehicle  12  can be realized. 
       (1B-4-4-1. Basic Concept) 
       [0106]    According to the present embodiment, the vehicle  12  travels on a trackless trajectory. Therefore, compared with a vehicle that travels on a track such as a railway vehicle, a high degree of freedom exists for the initial contact position and the separation position after contact with the external power lines  170 . Zn the case of a vehicle that travels on a track, the initial contact position and the separation position after contact with the external power lines  170  basically are the same. In contrast thereto, in an electric vehicle that travels on a trackless trajectory such as the vehicle  12 , it is preferable to entrust the initial contact position and the separation position to the intention of the driver. In the event that the travel path  190  is made up from multiple lanes and plural electric vehicles travel along the same travel path  190 , such a tendency becomes stronger. In particular, in a scenario where auto racing is held, such a tendency is even more remarkable. 
         [0107]    Thus, according to the present embodiment, by forming the external power lines  170  inside of a groove member  182  that is continuous along the travel path  190 , it is possible for the energizing head  70  to come into contact with and separate away at any position of the external power lines  170 . 
         [0108]    Additionally, according to the present embodiment, the implementation time of the current limiting control (first charging control) is shortened insofar as possible, whereas the implementation time of the direct connection control (second charging control) is made as long as possible. When considered from another point of view, by shortening the implementation time (absolute value) of the current limiting control, the relative time ratio of the implementation time of the direct connection control also is reduced. 
       (1B-4-4-2. Correspondence on the Side of the External Power Supplying Apparatus  14 ) 
       [0109]    Since the implementation time of the current limiting control is shortened insofar as possible, and the implementation time of the direct connection control is made as long as possible, with the power supplying apparatus  14 , at first, the discharge capacity of the DC power source  150  is comparatively high. In addition, sine in the direct connection control, in order to perform charging with high efficiency while avoiding power losses by the converter  28  (switching losses, etc.), the power supply voltage Vs is set to a value equivalent to the full charged voltage THvbatfull of the battery  24  or within a margin thereof (a value in consideration of a voltage drop or the like). 
         [0110]    Furthermore, concerning the total length Lip (length) of the external power lines  170 , in the case that the SOC of the battery  24  is a predetermined value (e.g., a fixed value of anywhere from 0% to 30%), and in a state in which the vehicle  12  is traveling at an assumed speed (e.g., any value from 20 to 150 km/h) (or within an expected range of speeds), in the case that contact occurs from a near end of the external power lines  170  to an end on the far side thereof, the total length Lip (length) is set so that the current limiting control is carried out within a range that is shorter than half the length of the power lines  170 . 
         [0111]    For example, if the SOC of the battery  24  is a value in the vicinity of 0% and contact with the external power lines  170  occurs in a state with the vehicle  12  traveling at an assumed speed, the current limiting control is completed at a contact length of 1 to 10 m, whereas the direct connection control is completed at a contact length of 19 to 150 m. As a result, the implementation time (absolute value) of the current limiting control is extremely short, and the relative time ratio of the implementation time of the direct connection control is significantly reduced. 
         [0112]    In addition, the current limiting control and direct connection control are completed even without contact with the power lines  170  over the entire length Lip of the external power lines  170 . For example, it is possible for the current limiting control and the direct connection control to be completed by being in contact at half the total length Llp or less. 
         [0000]    (1B-4-4-3. Correspondence with Side of Electric Vehicle  12 ) 
         [0113]    In order to shorten the implementation time of the current limiting control insofar as possible, and in order to make the implementation time of the direct connection control as long as possible, on the side of the electric vehicle  12 , the threshold value THΔibio of the current difference ΔIbio (rate of increase of the current Ibio) (steps S 23 , S 25  of  FIG. 8 ) in the current limiting control (step S 13  of  FIG. 6 ,  FIG. 8 ) is set to a value corresponding to 10 to 100 times the discharge capacity Wb of the battery  24  (for example, 60 times or greater). At this time, in order to realize the threshold value THΔibio, concerning the switching elements  86   u,    86   l  (or at least the switching element  86   u ), switching elements (for example, SiC type MOSFETs) preferably are used for which the rate of passage of the current is rapid. 
         [0114]    In addition, the direct connection control is used as a control that follows the current limiting control (however, as will be described later, it is possible for a different control to be used). By this feature, power losses within the converter  28  are avoided, and the charging time of the battery  24  can be shortened. 
       1C. Advantages of the Present Embodiment 
       [0115]    According to the present invention, when the energizing arm  26  (energizing portion) contacts the external power lines  170  (power supplying portion or power supplying lines), the current limiting control (first charging control) is carried out in which the input current (input/output current Ibio) to the battery  24  (energy storage device) is treated as the control object (step S 13  of  FIG. 6 ,  FIG. 8 ). Owing thereto, an instantaneous surge current at the time chat energizing is started can be prevented, and welding or fusion between the external power lines  170  and the energizing arm  26 , or damage to the electrical circuitry on the side of the external power lines  170  or on the side of the energizing arm  26  can be prevented. Further, after the current limiting control, the direct connection control (second charging control), in which supply of power without voltage conversion is performed, is carried out for a longer time period than the current limiting control (step S 15  of  FIG. 6 ,  FIG. 7 ). Accordingly, charging over an extremely short time is enabled by a combination of the current limiting control and the direct connection control. 
         [0116]    Furthermore, under a control environment ranging from the current limiting control to the direct connection control, by bringing the external power lines  170  and the energizing arm  26  into contact while the contact point therebetween is moved, generation of heat at the contact point is not concentrated in one location. Owing thereto, even if high current energizing is carried out in the direct connection control, which is performed longer than the current limiting control, welding or fusion between the external power lines  170  and the energizing arm  26 , or damage to the electrical circuitry on the side of the external power lines  170  or on the side of the energizing Bin  26  can be prevented. 
         [0117]    Further still, because charging can be performed in an extremely short time period by the current limiting control and the direct connection control, charging of the battery  24  (energy storage device) can be carried out reliably, even in situations that have been problematic in the case of traveling on a trackless trajectory, in which, according to the driver&#39;s intention, the contact position with the external power lines  170  and the separation position from the external power lines  170  are changed, and further, in which the charging time period is unpredictable due to the power supplying section, which is defined by the external power lines  170 , being traveled through at high speed. 
         [0118]    In addition, since charging can be performed in an extremely short time period, the installation distance (total length of the external power lines  170 ) between and the number of power supplying sections can be kept to a minimum, and investment costs in infrastructure can be reduced. 
         [0119]    When the battery input/output voltage Vbio (or the output voltage Vc 2  of the converter  28  (voltage converter)) during the direct connection control (second charging control) arrives at a fully charged voltage THvbatfull of the battery  24  (step S 16  of  FIG. 6 : YES), the ECU  52  (control device) implements the target voltage control (third charging control) for operating the converter  28  so as to maintain the voltage vbio at the fully charged voltage THvbatfull (step S 17  of  FIG. 6 ,  FIG. 9 ). Owing thereto, the battery  24  can be fully charged more reliably. 
         [0120]    In the present embodiment, the positive electrode terminal  76   p  and the negative electrode terminal  76   n  in the form of rollers that contact the external power lines  170  (power supplying portion or power supplying lines) are formed on the distal end of the energizing arm  26  (see  FIGS. 2 and 3 ). By this feature, damage to the power receiving portion  72  as a contact site of the energizing arm  26  with respect to the external power lines  170  can be lightened or alleviated. 
         [0121]    In the present embodiment, the electric vehicle  12  is equipped with the arm deployment mechanism  48  (arm displacement mechanism) that causes the energizing arm  26  to project out laterally of the vehicle body  62  during traveling (see  FIG. 2 ). Owing thereto, since it is possible for the external power lines  170  to be disposed laterally of the travel path  190 , installation of the external power lines  170  can be performed at low cost. More specifically, compared to a case in which the external power lines  170  are arranged upwardly of the vehicle body  62 , since it is possible to dispose the external power lines  170  at a lower position, it is possible to simplify equipment for supporting the external power lines  170 . Further, although it is necessary to embed the external power lines  170  in the travel path  190  in the case that the external power lines  170  are arranged below the vehicle body  62 , in the case that the external power lines  170  are arranged to the side of the travel path  190 , there is no need to embed the external power lines  170  in the travel path  190 . Therefore, it is possible for the external power lines  170  to be arranged with ease. 
       II. Modifications 
       [0122]    The present invention is not limited to the above-described embodiment, and it goes without saying that various configurations could be adopted therein, based on the content disclosed in the present specification. For example, the following configurations can be adopted. 
       2A. Vehicle  12   
     [2A-1. Type of Vehicle  12 ] 
       [0123]    According to the above-described embodiment, a vehicle  12  in the form of a four-wheeled vehicle has been described (see  FIG. 2 ). However, for example, insofar as attention is paid to the power receiving control of the vehicle  12  (see  FIG. 6 ), it is possible for the present invention to be applied to other vehicles apart from a four-wheeled vehicle. For example, the vehicle  12  can be any of a two-wheeled vehicle, a three-wheeled vehicle, and a six-wheeled vehicle. Alternatively, the present invention can be applied to mobile objects (e.g., ships) other than the vehicle  12 . 
         [0124]    According to the above-described embodiment, the vehicle  12  is assumed to be a so-called electric automobile (battery vehicle) having only the traction motor  20  as a drive source (see  FIG. 1 ). However, for example, insofar as attention is paid to the power receiving control of the vehicle  12  (see  FIG. 6 ), the vehicle  12  may be an electric vehicle other than an electrically powered automobile. For example, the vehicle  12  may be a fuel cell vehicle or a hybrid vehicle. 
       [2A-2. Circuit Configuration] 
       [0125]    According to the above-described embodiment, the electrical circuit configuration for the vehicle  12  is as shown in  FIG. 1 . However, for example, insofar as attention is paid to the power receiving control of the vehicle  12  (see  FIG. 6 ), the invention is not limited to this feature. For example, it is possible for the position of the converter  28  on the side of the vehicle to be changed. 
         [0126]      FIG. 10  is an outline schematic view of a charging system  10 A equipped with an electric vehicle  12   a  (hereinafter also referred to as a “vehicle  12   a” ) according to a modification of the present invention. The converter  28  of the vehicle  12  according to the above-described embodiment is arranged between the power receiving portion  72  and the branch points  90   p,    90   n  (see  FIG. 1 ). In contrast thereto, a converter  28   a  of the vehicle  12   a  according to the modification is arranged between the battery  24  and the branch points  90   p,    90   n  (see  FIG. 10 ). 
       [2A-3. Energizing Arm  26  (Energizing Portion)] 
       [0127]    According to the above-described embodiment, the arm  26  is arranged (see  FIGS. 2 and 3 ) so as to be capable of being deployed laterally on the right side of the vehicle body  62 . However, for example, insofar as attention is paid to the power receiving control of the vehicle  12  (see  FIG. 6 ), the invention is not limited to this feature, and the arm  26  may be arranged on a left side, an upper side, or a lower side of the vehicle body  62 . It should be noted, in the case that the arrangement of the arm  26  is changed, it becomes necessary for the arrangement of the external power lines  170  of the power supplying apparatus  14  also to be changed. 
         [0128]    According to the above-described embodiment, when the energizing arm  26  comes into proximity and contacts the contact-type power supplying portion  152 , the arm  26  is rotated about the axis off rotation  60  (see  FIG. 2 ). However, for example, insofar as attention is paid to the power receiving control of the vehicle  12  (see  FIG. 6 ), the invention is not limited to this feature. For example, it is possible for a mechanism to be provided that displaces the arm  26  linearly, and which causes the arm  26  to approach and come into contact linearly with the contact-type power supplying portion  152 . Alternatively, even in the absence of displacement with respect to the vehicle body  62 , a configuration may be provided as an energizing portion, which is capable of contacting the power supplying portion (external power lines  170 , etc.) on the side of the power supplying apparatus  14 . 
       2B. External Power Supplying Apparatus  14   
     [2B-1. External Power Lines  170 ] 
       [0129]    According to the above-described embodiment, the external power lines  170  are disposed in a straight line shape (see  FIG. 2 ). However, for example, insofar as attention is paid to the power receiving control of the vehicle  12  (see  FIG. 6 ), the external power lines  170  may be disposed along a curved road. 
       [2B-2. Other Features] 
       [0130]    According to the above-described embodiment, the external converter  154  is controlled by the control device  162 , whereby the power supply voltage Vs of the external power lines  170  is controlled. However, for example, in the case that the power source  150  is constituted in the form of an aggregation of multiple DC power sources (e.g., batteries) connected together in series, it is possible to eliminate the converter  154  and the control device  162 . 
       2C. Power Receiving Control 
     [2C-1. Generally] 
       [0131]    In the above-described embodiment, in the power receiving control, there are included the current limiting control, the direct connection control (voltage and current unlimited control), and the target voltage control (see  FIG. 6 ). However, for example, insofar as attention is focused on the current limiting control and the direct connection control, it is possible to omit the target voltage control. 
         [0132]    In the power receiving control according to the above-described embodiment, with the process (e.g., step S 14  of  FIG. 6 ) in which the battery input/output voltage Vbio is used as the control object, the converter output voltage Vc 2  can also be used. Similarly, with the process (e.g., steps S 22 , S 23 , S 25  of  FIG. 8 ) in which the battery input/output current Ibio is used as the control object, the converter output current Ic 2  can also be used. 
       [2C-2. Current Limiting Control (First Charging Control)] 
       [0133]    With the current limiting control of the above-described embodiment, a control is used for controlling the rate of increase of the battery input/output current Ibio to be less than or equal to a predetermined value (threshold value THΔibio) (see  FIG. 8 ). However, for example, from the standpoint of limiting the current Ibio or a change therein, the invention is not limited to this feature. For example, a constant current control also is possible. More specifically, the ECU  52  may set a target value (target current Ibiotar) for the current Ibio, and the conversion ratio Rcon of the converter  28  may be controlled so that the current Ibio coincides with the target current Ibiotar. 
       [2C-3. Voltage and Current Unlimited Control (Second Charging Control)] 
       [0134]    According to the above-described embodiment, the direct connection control is used as a control (second charging control) that follows the current limiting control (step S 15  of  FIG. 6 ). However, for example, from the standpoint of a control (voltage and current unlimited control) in which the voltage Vbio and the current Ibio are not limited directly, the invention is not limited to this feature. For example, it is possible to carry out a target power control in which a target value (target power Pbiotar) of the electrical power supplied to the battery  24  (hereinafter referred to as a “supplied power Pbio”, a “battery input/output power Pbio”, or a power “Pbio”) is set, and the supplied power Pbio is controlled so as to coincide with the target power Pbiotar. 
         [0135]      FIG. 11  is a flowchart of the target power control. The target power control is used in place of the direct connection control (step S 15  of  FIG. 6 ). In step S 41 , the ECU  52  acquires the battery input/output voltage Vbio and the battery input/output current Ibio. In step S 42 , the ECU  52  calculates the battery input/output power Pbio by multiplying the voltage Vbio and the current Ibio. 
         [0136]    In step S 43 , the ECU  52  determines whether or not the power Pbio is equal to a threshold value (hereinafter referred to as a “threshold value THpbio”). The threshold value THpbio, for example, can be set to a value that allows the converter  28  to carry out voltage conversion with relatively high efficiency. If the power Pbio equals the threshold value THpbio (step S 43 : YES), then in step S 44 , the ECU  52  maintains the conversion ratio Rcon of the converter  28 . If the power Pbio is not equal to the threshold value THpbio (step S 43 : NO), the routine proceeds to step S 45 . Instead of using the threshold value THpbio (single value), the determination of step S 43  can utilize a fixed range that includes the threshold value THpbio. 
         [0137]    In step S 45 , the ECU  52  determines whether or not the power Pbio falls below the threshold value THpbio. If the power Pbio falls below the threshold value THpbio (step S 45 : YES), then in step S 46 , the ECU  52  changes the conversion ratio Rcon of the converter  28  so as to increase the input/output power Pbio (and the input/output voltage Vbio). 
         [0138]    If the power Pbio does not fall below the threshold value THpbio (step S 45 : NO), the power Pbio exceeds the threshold value THpbio (Pbio&gt;THpbio). In this case, in step S 47 , the ECU  52  changes the conversion ratio Rcon of the converter  28  so as to decrease the input/output power Pbio (and the input/output voltage Vbio). 
       2D. Other Features 
       [0139]    According to the above-described embodiment ( FIG. 1 ) and the above described modification ( FIG. 10 ), a configuration has been described in which only supply of electrical power to the vehicle  12  from the power supplying apparatus  14  is carried out. However, conversely, the present invention is capable of being applied to a configuration in which supply of power from the vehicle  12  to the power supplying apparatus  14  is carried out. In this case, insofar as generation of power can be performed by a generator from gasoline or the like in the vehicle  12 , it is possible not to provide the battery  24  or an energy storage device for supplying electrical power to the traction motor  20 . 
         [0140]    According to the above-described embodiment, the present invention is applied to a case in which supply of power by direct current is performed with respect to the vehicle  12  from the power supplying apparatus  14 . However, for example, insofar as attention is paid to the power receiving control of the vehicle  12  (see  FIG. 6 ), it is possible for the present invention to be applied to a case in which supply of power by an alternating current is performed with respect to the vehicle  12  from the power supplying apparatus  14 . 
         [0141]    According to the above-described embodiment, by displacing the energizing arm  26  (energizing portion) of the vehicle  12  with respect to the external power lines  170  (power supplying portion or power supplying lines) of the power supplying apparatus  14 , charging is carried out while both contact points undergo movement. Stated otherwise, charging is performed with the external power lines  170  being in a stationary state, and while the arm  26  is in a moving state. 
         [0142]    However, for example, insofar as attention is paid to carrying out charging while the contact point on the side of the power supplying apparatus  14  is moved, the invention is not limited to this feature. For example, a configuration is possible in which the power supplying portion of the power supplying apparatus  14  is displaced with respect to the energizing portion of the vehicle  12  (stated otherwise, with the vehicle  12  in a stationary state, charging is carried out while displacing the power supplying portion). In such a case, an energizing portion displacement mechanism is provided in which an energizing portion (for example, the external power lines  170 ) of the power supplying apparatus  14  is displaced with respect to the energizing portion that remains in a stationary state. Displacement of the energizing portion in this manner, for example, can involve linear movement in one direction or reciprocal movement. Alternatively, in the case that the energizing portion is formed in an arcuate shape or an annular shape, the energizing portion can be subjected to rotational movement.