Patent Publication Number: US-11648852-B2

Title: Vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application No. 2020-162152 filed on Sep. 28, 2020, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The disclosure relates to a vehicle. 
     In recent years, there has been proposed a technique for updating a program of an electronic control unit that controls an engine, a motor, and other vehicle-mounted devices installed in a vehicle. Hereinafter, updating a program is also referred to as reprogramming. 
     Reprogramming is commonly performed when a vehicle and an engine are stopped. Thus, reprogramming is performed by using electric power stored in a battery such as a 12V accessory battery (low-voltage battery) (see, for example, Japanese Unexamined Patent Application Publication No. 2017-166434). 
     SUMMARY 
     An aspect of the disclosure provides a vehicle including a high-voltage system circuit, a low-voltage system circuit, a direct current (DC)-DC converter, and a controller. The high-voltage system circuit includes a high-voltage battery. The low-voltage system circuit includes a low-voltage battery and an updater. The low-voltage battery has a lower output voltage than the high-voltage battery. The updater is configured to update a program of an update-target device by using electric power supplied from the low-voltage battery or the high-voltage battery. The DC-DC converter is coupled between the high-voltage system circuit and the low-voltage system circuit and is capable of reducing in voltage output electric power of the high-voltage battery and supplying the electric power reduced in voltage to the low-voltage system circuit. The controller is configured to control the high-voltage system circuit, the low-voltage system circuit, and the DC-DC converter. The controller is configured to determine whether the update-target device is a certain device relating to electric power supply from the high-voltage battery to the low-voltage system circuit. In a case where the update-target device is the certain device, the controller is configured to cause the DC-DC converter to reduce the output electric power of the high-voltage battery and to supply the reduced electric power to the low-voltage system circuit so as to charge the low-voltage battery, configured to cause the certain device to stop operating after the low-voltage battery is charged, and configured to cause the updater to update the program of the certain device by using the output electric power of the low-voltage battery. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate an example embodiment and, together with the specification, serve to explain the principles of the disclosure. 
         FIG.  1    is a functional block diagram for describing a vehicle in accordance with an embodiment; 
         FIG.  2    is a block diagram illustrating an electric/electronic system circuit that is controlled by a control device in accordance with the embodiment; 
         FIGS.  3 A and  3 B  are diagrams for describing how a target state of charge (SOC) of a high-voltage battery is controlled by a high-voltage battery controller in accordance with the embodiment; 
         FIG.  4    is a diagram illustrating a reprogramming confirmation screen in accordance with the embodiment; 
         FIGS.  5 A and  5 B  are flowcharts for describing a control process performed in relation to reprogramming in the vehicle in accordance with the embodiment; and 
         FIG.  6    is a flowchart for describing a reprogramming operation control process performed in the vehicle in accordance with the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In recent years, time taken for reprogramming tends to increase because of an increase in a program capacity or the like. If the time taken for reprogramming increases, electric power used for reprogramming increases. Thus, if electric power is not sufficiently stored in a battery at the time of reprogramming, updating of a program may be aborted because of a deficiency of electric power. 
     Accordingly, when a charge level of a 12V accessory battery (low-voltage battery) is deficient, reprogramming is conceivably performed by reducing output electric power of a high-voltage battery for driving a motor used by a vehicle to travel and by using the reduced electric power as electric power for reprogramming. However, there is room for improvement of the method of using, as the electric power for reprogramming, the electric power supplied from the high-voltage battery instead of the 12V accessory battery in that it is difficult to perform reprogramming of a device relating to electric power supply from the high-voltage battery to a low-voltage system circuit. 
     Accordingly, it is desirable to provide a vehicle capable of reducing the likelihood of updating of a program being aborted because of a deficiency of electric power and capable of performing reprogramming of a device relating to electric power supply from a high-voltage battery to a low-voltage system circuit. 
     In the following, an embodiment of the disclosure is described in detail with reference to the accompanying drawings. Note that the following description is directed to an illustrative example of the disclosure and not to be construed as limiting to the disclosure. Factors including, without limitation, numerical values, shapes, materials, components, positions of the components, and how the components are coupled to each other are illustrative only and not to be construed as limiting to the disclosure. Further, elements in the following example embodiment which are not recited in a most-generic independent claim of the disclosure are optional and may be provided on an as-needed basis. The drawings are schematic and are not intended to be drawn to scale. Throughout the present specification and the drawings, elements having substantially the same function and configuration are denoted with the same numerals to avoid any redundant description. 
       FIG.  1    is a functional block diagram for describing a vehicle  1  in accordance with an embodiment. The vehicle  1  including an engine  10  and a motor  12  as driving sources for traveling is presented as an example. The vehicle  1  according to the embodiment is, for example, a so-called parallel hybrid vehicle. The engine  10  is mainly used as a motive power source to cause an output shaft  14  to rotate. The motor  12 , which is a three-phase alternating current (AC) motor, is also a motive power source but merely plays a role of assisting the engine  10 . A drive mode in which the engine  10  and the motor  12  are jointly used is referred to as a joint use mode. 
     At the time of low-speed traveling in which the speed of the engine  10  is low such as at the time when the vehicle  1  starts traveling or starts accelerating, power or torque of the engine  10  is small. Thus, a clutch  16  is released, and the drive mode is switched from the joint use mode to an electric vehicle (EV) mode in which the motor  12  alone is used as the motive power source. The drive mode is switchable from the joint use mode to the EV mode in accordance with a traveling state at the times other than the time when the vehicle  1  starts traveling or starts accelerating. 
     An endless member such as a belt  20  extends around an integrated starter generator (ISG)  18  and the output shaft  14  of the engine  10 , so that the ISG  18  is coupled to the engine  10 . Consequently, the ISG  18  functions as a starter motor that transfers motive power to the engine  10  to assist the engine  10  in starting. The ISG  18  also functions as an alternator that regenerates electric power. Conceivable timings when the engine  10  is started include not only a timing when the vehicle  1  starts traveling but also various timings such as a timing when the drive mode is switched from the EV mode to the joint use mode and a timing when the engine  10  in a non-idling state is restarted. 
     A control device  22  includes, for example, semiconductor integrated circuits including a central processing unit (CPU), a read-only memory (ROM) that stores a program or the like, and a random access memory (RAM) that serves as a work area. The control device  22  controls the entire vehicle  1  or various devices installed in the vehicle  1 . For example, the control device  22  controls each component of an electric/electronic system circuit that includes a high-voltage battery  32  (see  FIG.  2   ) and a low-voltage battery  42  (see  FIG.  2   ), which will be described later. 
     The control device  22  is coupled to a wireless communication device  50   a  (see also  FIG.  2   ) and is capable of transmitting and receiving various kinds of data to and from an external device via the wireless communication device  50   a . The wireless communication device  50   a  is capable of wirelessly communicating with a data distribution center  102  via a network  100 . The data distribution center  102  has a function of distributing reprogramming information for use in updating of a program for controlling an update-target device  44  (see  FIG.  2    described later) installed in the vehicle  1 . The reprogramming information includes, for example, information for designating the update-target device  44  for which reprogramming is performed, and information on update data for use in reprogramming. 
     The control device  22  includes an automotive navigation system controller  52   a  (see  FIG.  2   ) described later. The automotive navigation system controller  52   a  enables various kinds of information such as map information to be displayed on a display  24  coupled to the control device  22 . 
       FIG.  2    is a block diagram illustrating the electric/electronic system circuit that is controlled by the control device  22  in accordance with the embodiment. As illustrated in  FIG.  2   , the electric/electronic system circuit installed in the vehicle  1  includes a high-voltage system circuit  30 , a low-voltage system circuit  40 , and a direct current (DC)-DC converter  60 . The high-voltage system circuit  30  includes the high-voltage battery  32  and a high-voltage relay  34 . The high-voltage relay  34  is a relay device that switches on and off the electrical coupling of the high-voltage battery  32  in the high-voltage system circuit  30 . 
     The low-voltage system circuit  40  includes the low-voltage battery  42 , the update-target device  44 , an updater  46 , and a vehicle load  48 . The low-voltage battery  42  is a rechargeable battery having a lower output voltage than the high-voltage battery  32 . The low-voltage battery  42  is, for example, a 12V accessory battery and supplies relatively-low-voltage (for example, 12V) DC electric power to various vehicle-mounted devices (accessories) installed in the vehicle  1 . The updater is a program updating tool that performs updating of a program (reprogramming) of the update-target device  44  in accordance with an instruction of the control device  22 . The updater  46  performs reprogramming of the update-target device by using electric power supplied from the low-voltage battery  42  or the high-voltage battery  32 . Examples of the vehicle load  48  include electrical loads such as a door-mirror motor (not illustrated), a power-window motor (not illustrated), and a radiator-fan motor (not illustrated), for example. 
     In one example, the update-target device  44  is, for example, an engine controller  10   a , a motor controller  12   a , a high-voltage battery controller  32   a , a high-voltage relay controller  34   a , a low-voltage battery controller  42   a , the wireless communication device  50   a , the automotive navigation system controller  52   a , an ignition power supply (IG power supply) controller  54   a , or a DC-DC converter controller  60   a . The engine controller  10   a  controls the engine  10 . The motor controller  12   a  controls the motor  12 . The high-voltage battery controller  32   a  controls the high-voltage battery  32 . The high-voltage relay controller  34   a  controls the high-voltage relay  34 . The low-voltage battery controller  42   a  controls the low-voltage battery  42 . The wireless communication device  50   a  wirelessly communicates with the data distribution center  102  via the network  100 . The automotive navigation system controller  52   a  controls an automotive navigation system. The IG power supply controller  54   a  controls an IG power supply of the vehicle  1  to be in an IG-ON (READY-ON) or IG-OFF (READY-OFF) state on the basis of a user operation. The DC-DC converter controller  60   a  controls operation of the DC-DC converter  60 . 
     The DC-DC converter  60  is coupled between the high-voltage system circuit  30  and the low-voltage system circuit  40 . The DC-DC converter  60  is capable of reducing in voltage output electric power of the high-voltage battery  32  of the high-voltage system circuit  30  and of supplying the electric power reduced in voltage to the low-voltage battery  42 , the update-target device  44 , the updater  46 , the vehicle load  48 , etc. of the low-voltage system circuit  40 . That is, the DC-DC converter  60  can reduce a voltage of output electric power of the high-voltage battery  32  of the high-voltage system circuit  30  and supply the electric power with reduced voltage to the low-voltage battery  42 , the update-target device  44 , the updater  46 , the vehicle load  48 , etc. of the low-voltage system circuit  40 . 
     The high-voltage battery controller  32   a  sets a target state-of-charge (SOC) range, that is, an upper-limit value and a lower-limit value, for the high-voltage battery  32 , and controls charging and discharging of the high-voltage battery  32  in accordance with this target SOC range. 
       FIGS.  3 A and  3 B  are diagrams for describing how the target SOC of the high-voltage battery  32  is controlled by the high-voltage battery controller  32   a . As illustrated in  FIG.  3 A , at normal time when no reprogramming is scheduled, the high-voltage battery controller  32   a  sets, as the target SOC range, a normal SOC upper-limit value and a normal SOC lower-limit value. For example, the normal SOC upper-limit value may be set to 90% of the fully charged state of the high-voltage battery  32  which is represented as 100%. For example, the normal SOC lower-limit value may be set to 50% of the fully charged state of the high-voltage battery  32  which is represented as 100%. The normal SOC upper-limit and lower-limit values are not limited to these specific examples. 
     In response to the wireless communication device  50   a  receiving reprogramming information from the data distribution center  102  via the network  100  and reprogramming being scheduled, the high-voltage battery controller  32   a  changes the target SOC lower-limit value of the high-voltage battery  32  to a value (scheduled reprogramming preparation value) that is higher than the normal lower-limit value (normal SOC lower-limit value). The high-voltage battery controller  32   a  sets the SOC upper-limit value to the normal SOC upper-limit value. 
     In one example, when the wireless communication device  50   a  receives reprogramming information from the data distribution center  102  via the network  100 , the high-voltage battery controller  32   a  determines that reprogramming is scheduled. The high-voltage battery controller  32   a  calculates electric power used for reprogramming of the update-target device  44  (hereinafter, also referred to as “electric power for reprogramming”) on the basis of the received reprogramming information. 
     In one example, the reprogramming information includes various kinds of information such as a program capacity for the update-target device  44 , a write speed of writing the update program to the update-target device  44 , electric power consumption per unit time during reprogramming, and a communication speed between the updater  46  and the update-target device  44 , for example. The high-voltage battery controller  32   a  calculates the electric power for reprogramming on the basis of all or some of these various kinds of information. 
     On the basis of the calculated electric power for reprogramming, the high-voltage battery controller  32   a  changes the target SOC lower-limit value of the high-voltage battery  32  to the scheduled reprogramming preparation value that is higher than the normal value. For example, the high-voltage battery controller  32   a  sets the target SOC lower-limit value of the high-voltage battery  32  to the scheduled reprogramming preparation value (for example, 70% of the fully charged state) that is higher than the normal value (for example, 50% of the fully charged state). In some embodiments, the target SOC lower-limit value (scheduled reprogramming preparation value) is set to a larger value as the calculated electric power for reprogramming becomes larger. Consequently, the high-voltage battery  32  is sufficiently charged and a charge level higher than or equal to the electric power for reprogramming can be ensured. Thus, a deficiency of electric power during reprogramming is successfully avoided. 
     In the embodiment, the high-voltage battery controller  32   a  calculates the electric power for reprogramming of the update-target device  44  on the basis of the reprogramming information. The high-voltage battery controller  32   a  changes the target SOC lower-limit value of the high-voltage battery  32  on the basis of the calculated electric power for reprogramming. However, the embodiment of the disclosure is not limited to this. For example, in response to the wireless communication device  50   a  receiving reprogramming information from the data distribution center  102  via the network  100  and reprogramming being scheduled, the high-voltage battery controller  32   a  may set a predetermined SOC lower-limit value as the target SOC lower-limit value (scheduled reprogramming preparation value) of the high-voltage battery  32 . For example, the SOC lower-limit value serving as the scheduled reprogramming preparation value may be set in advance to 70% of the fully charged state of the high-voltage battery  32  which is represented as 100%. 
     Alternatively, the reprogramming information may include electric power information on the electric power used for reprogramming of the update-target device  44 . In this case, the high-voltage battery controller  32   a  changes the target SOC lower-limit value of the high-voltage battery  32  on the basis of the electric power information. 
     The high-voltage battery controller  32   a  then changes the target SOC lower-limit value of the high-voltage battery  32  to the scheduled reprogramming preparation value. The high-voltage battery  32  is charged to a charge level that is higher than or equal to the scheduled reprogramming preparation value. In response to a user operation (IG-OFF operation) for setting the vehicle  1  to READY-OFF performed in a state in which reprogramming is scheduled, the updater  46  checks the charge levels of the high-voltage battery  32  and the low-voltage battery  42 . 
       FIG.  4    is a diagram illustrating a reprogramming confirmation screen  24   a  in accordance with the embodiment. If the charge level of the low-voltage battery  42  is higher than or equal to the electric power level used for reprogramming of the update-target device  44  and thus reprogramming of the update-target device  44  can be performed by using the low-voltage battery  42 , or if the charge level of the high-voltage battery  32  is higher than or equal to the scheduled reprogramming preparation value, the automotive navigation system controller  52   a  causes the reprogramming confirmation screen  24   a  to be displayed on the display  24  as illustrated in  FIG.  4   . The reprogramming confirmation screen  24   a  asks for the user&#39;s confirmation to perform reprogramming. 
     In the reprogramming confirmation screen  24   a , for example, a warning message “Once reprogramming starts, the vehicle  1  is not usable until reprogramming ends” and button images that allow the user to select whether to confirm reprogramming (Yes or No) are displayed. 
     If the user presses the “Yes” button in the reprogramming confirmation screen  24   a  to confirm reprogramming, a reprogramming operation starts. On the other hand, if the user presses the “No” button in the reprogramming confirmation screen  24   a  to reject reprogramming or if neither the “Yes” button nor the “No” button is pressed by the user in the reprogramming confirmation screen  24   a , the reprogramming operation does not start. 
     In response to the start of the reprogramming operation, the updater  46  performs reprogramming of the update-target device  44  by using electric power of the low-voltage battery  42  if reprogramming of the update-target device  44  can be performed by using the low-voltage battery  42 . 
     On the other hand, if the charge level of the low-voltage battery  42  is not sufficient and thus reprogramming of the update-target device  44  is unable to be performed by using the low-voltage battery  42 , in order to perform reprogramming by using the high-voltage battery  32 , the high-voltage relay controller  34   a  brings the high-voltage relay  34  into a coupled state to enable electric power of the high-voltage battery  32  to be output to the DC-DC converter  60 . The DC-DC converter controller  60   a  causes the DC-DC converter  60  to start operating, to reduce in voltage electric power output from the high-voltage battery  32 , and to supply the electric power reduced in voltage to the low-voltage system circuit  40 . 
     At this time, the updater  46  determines whether the update-target device  44  subjected to reprogramming is a certain device used for supplying electric power from the high-voltage battery  32 . Examples of such a certain device include the high-voltage battery controller  32   a , the DC-DC converter controller  60   a , and the high-voltage relay controller  34   a , for example. 
     If the update-target device  44  subjected to reprogramming is not the certain device used for supplying electric power from the high-voltage battery  32 , the updater  46  performs reprogramming of the update-target device  44  by using electric power supplied from the high-voltage battery  32  to the low-voltage system circuit  40 . In response to the end of reprogramming, the DC-DC converter controller  60   a  causes the DC-DC converter  60  to stop operating and the high-voltage relay controller  34   a  breaks the coupling of the high-voltage relay  34 . 
     If the update-target device  44  subjected to reprogramming is the certain device used for supplying electric power from the high-voltage battery  32 , reprogramming of the update-target device  44  by the updater  46  is not performed in a state in which the low-voltage system circuit  40  is being supplied with electric power from the high-voltage battery  32 . Thus, in the embodiment, the update-target device  44  (certain device) or the like is temporarily used to supply electric power to the low-voltage battery  42  from the high-voltage battery  32  through the DC-DC converter  60  and to sufficiently charge the low-voltage battery  42 . After charging of the low-voltage battery  42  ends, electric power supply from the high-voltage battery  32  is stopped and the update-target device  44  (certain device) is caused to stop operating. Then, the updater  46  performs reprogramming of the update-target device  44  (certain device) by using electric power supplied from the low-voltage battery  42 . 
     In one example, the low-voltage battery controller  42   a  charges the low-voltage battery  42  until the charge level of the low-voltage battery  42  becomes equal to a level with which reprogramming of the update-target device  44  can be performed by using the low-voltage battery  42 . At this time, the low-voltage battery controller  42   a  can determine the charge level of the low-voltage battery  42  on the basis of the electric power used for reprogramming of the update-target device  44  which is calculated by the high-voltage battery controller  32   a . The configuration is not limited to such an example. The low-voltage battery controller  42   a  may charge the low-voltage battery  42  to a predetermined charge level set in advance. For example, this predetermined charge level may be set in advance to 90% of the fully charged state of the low-voltage battery  42  which is represented as 100%. 
     In response to the completion of charging of the low-voltage battery  42 , the DC-DC converter controller  60   a  ends the operation of the DC-DC converter  60  and the high-voltage relay controller  34   a  breaks the coupling of the high-voltage relay  34 . Then, the updater  46  performs reprogramming of the update-target device  44  by using electric power of the low-voltage battery  42  that has been charged. 
     Control Method 
       FIGS.  5 A and  5 B  are flowcharts for describing a control process performed in relation to reprogramming in the vehicle  1  in accordance with the embodiment. 
     As illustrated in  FIG.  5 A , in response to a user operation, the IG power supply controller  54   a  of the control device  22  switches on the IG power supply and controls the vehicle  1  to be in the READY-ON (IG-ON) state (step S 101 ). 
     The control device  22  wirelessly communicates with the data distribution center  102  via the wireless communication device  50   a  and checks whether reprogramming data yet to be received by the vehicle  1  of interest is present in reprogramming data distributed from the data distribution center  102  (step S 103 ). The reprogramming data is data including update data for updating a program of the update-target device  44 . The data distribution center  102  distributes reprogramming information including the reprogramming data for performing reprogramming to each vehicle  1  via the network  100  when it is desirable to perform reprogramming of the update-target device  44 . 
     If it is determined in S 103  that yet-to-be-received reprogramming data is not present (NO in step S 103 ), the high-voltage battery controller  32   a  of the control device  22  determines whether a reprogramming data reception flag is on (step S 105 ). If the reprogramming data reception flag is on, the vehicle  1  of interest has already received reprogramming data but reprogramming is yet to be performed in accordance with the reprogramming data. Thus, the reprogramming data reception flag indicates a state in which reprogramming is to be performed (reprogramming is scheduled). 
     If it is determined in S 105  that the reprogramming data reception flag is off (NO in step S 105 ), reprogramming is not to be performed. Thus, the high-voltage battery controller  32   a  sets the SOC lower-limit and upper-limit values of the high-voltage battery  32  to the normal values (step S 107 ). As a result of this, the high-voltage battery  32  is charged, for example, during traveling of the vehicle  1  thereafter within the normal target SOC range (see  FIG.  3 A ). 
     The IG power supply controller  54   a  of the control device  22  then controls the vehicle  1  to be in the READY-OFF (IG-OFF) state in response to a user operation (step S 109 ). The control process then ends. 
     On the other hand, if it is determined in step S 105  that the reprogramming data reception flag is on (YES in step S 105 ), the process proceeds to S 117  (described below). 
     If it is determined in step S 103  that the yet-to-be-received reprogramming data is present and the reprogramming data is to be received from the data distribution center  102  (YES in step S 103 ), the control device  22  receives reprogramming information including the reprogramming data from the data distribution center  102  via the network  100  and the wireless communication device  50   a  (step S 111 ). 
     The high-voltage battery controller  32   a  of the control device  22  calculates electric power used for reprogramming of the update-target device  44  on the basis of the reprogramming information received from the data distribution center  102  (step S 113 ), and sets the reprogramming data reception flag on (step S 115 ). That is, in response to the wireless communication device  50   a  receiving the reprogramming data, the reprogramming data reception flag is set on and reprogramming is scheduled. The reprogramming data reception flag is not set off until reprogramming is completed. 
     If it is determined in step S 105  that the reprogramming data reception flag is on (YES in step S 105 ) or if the reprogramming data reception flag is set on in step S 115 , the high-voltage battery controller  32   a  of the control device  22  determines that reprogramming is scheduled. The high-voltage battery controller  32   a  of the control device  22  then changes the set target SOC lower-limit value of the high-voltage battery  32  to the scheduled reprogramming preparation value that is higher than the normal value on the basis of the calculated electric power used for reprogramming of the update-target device  44  and sets the SOC upper-limit value to the normal value (step S 117 ). As a result of this, the high-voltage battery  32  is charged, for example, during traveling of the vehicle  1  thereafter within a special target SOC range set when reprogramming is scheduled (see  FIG.  3 B ). 
     For example, in the case where the vehicle  1  stops thereafter, the IG power supply controller  54   a  of the control device  22  controls the vehicle  1  to be in the READY-OFF (IG-OFF) state in response to a user operation (step S 119 ). 
     The control device  22  checks the charge level of the low-voltage battery  42  and determines whether the charge level of the low-voltage battery  42  is higher than or equal to the electric power level used for reprogramming of the update-target device  44 , that is, whether reprogramming can be performed by using the low-voltage battery  42  (step S 121 ). 
     If it is determined that reprogramming is not to be performed by using the low-voltage battery  42  (NO in step S 121 ), the control device  22  checks the charge level of the high-voltage battery  32  and determines whether the charge level (actual SOC) of the high-voltage battery  32  is higher than or equal to the scheduled reprogramming preparation value (target SOC lower-limit value) (step S 123 ). 
     If it is determined that the charge level of the high-voltage battery  32  is higher than or equal to the scheduled reprogramming preparation value (YES in step S 123 ) or if it is determined that reprogramming can be performed by using the low-voltage battery  42  (YES in step S 121 ), the automotive navigation system controller  52   a  of the control device  22  causes the reprogramming confirmation screen  24   a  (see  FIG.  4   ) to be displayed on the display  24  (step S 125 ). 
     The control device  22  then determines whether the “Yes” button is operated by the user in the reprogramming confirmation screen  24   a  (step S 127 ). If it is determined that the “Yes” button is operated in the reprogramming confirmation screen  24   a  and reprogramming is confirmed by the user (YES in step S 127 ), the control device  22  performs a reprogramming operation control process (step S 200 ) by using the updater  46 . The reprogramming operation control process (step S 200 ) will be described later. In response to the end of the reprogramming operation control process (step S 200 ), the control device  22  sets the reprogramming data reception flag off. The process then ends. 
     On the other hand, if the “No” button is operated in the reprogramming confirmation screen  24   a  in step S 127  or if neither the “Yes” button nor the “No” button is operated by the user in the reprogramming confirmation screen  24   a  (NO in step S 127 ), the control device  22  ends the process without performing the reprogramming operation. If it is determined in step S 123  that the charge level of the high-voltage battery  32  is lower than the scheduled reprogramming preparation value (NO in step S 123 ), the control device  22  ends the process without performing the reprogramming operation. 
     Reprogramming Operation Control Process 
       FIG.  6    is a flowchart for describing the reprogramming operation control process (step S 200  in  FIG.  5 B ) performed in the vehicle  1  in accordance with the embodiment. 
     As illustrated in  FIG.  6   , the control device  22  first checks the charge level of the low-voltage battery  42  and determines whether the charge level of the low-voltage battery  42  is higher than or equal to the electric power level used for reprogramming of the update-target device  44 , that is, whether reprogramming can be performed by using the low-voltage battery  42  (step S 201 ). 
     If it is determined that reprogramming is not to be performed by using the low-voltage battery  42  (NO in step S 201 ), the high-voltage relay controller  34   a  of the control device  22  brings the high-voltage relay  34  into a coupled state (step S 203 ). The DC-DC converter controller  60   a  causes the DC-DC converter  60  to start operating, to reduce in voltage the electric power output from the high-voltage battery  32 , and to supply the electric power reduced in voltage to the low-voltage system circuit  40  (step S 205 ). As a result of this, the low-voltage battery  42  can be charged by using electric power supplied from the high-voltage battery  32 . Further, in the low-voltage system circuit  40 , reprogramming of the update-target device  44  can be performed by using electric power supplied from the high-voltage battery  32 . 
     The control device  22  determines whether the update-target device  44  subjected to reprogramming is a certain device used for supplying electric power from the high-voltage battery  32  (step S 207 ). In one example, such a certain device is, for example, the high-voltage battery controller  32   a , the DC-DC converter controller  60   a , or the like as described above. 
     If it is determined that the update-target device  44  subjected to reprogramming is not the certain device used for supplying electric power from the high-voltage battery  32 , the control device  22  instructs the updater  46  to perform reprogramming. The updater  46  starts reprogramming of the update-target device  44  by using the electric power supplied from the high-voltage battery  32  (step S 209 ). In response to the end of reprogramming (YES in step S 211 ), the DC-DC converter controller  60   a  causes the DC-DC converter  60  to stop operating (step S 213 ) and the high-voltage relay controller  34   a  breaks the coupling of the high-voltage relay  34  (step S 215 ). The process then ends. 
     On the other hand, if the update-target device  44  subjected to reprogramming is the certain device used for supplying electric power from the high-voltage battery  32  (YES in step S 207 ), the low-voltage battery controller  42   a  of the control device  22  determines whether charging of the low-voltage battery  42  is completed by using electric power output from the high-voltage battery  32  (step S 217 ). In one example, the low-voltage battery controller  42   a  determines whether the charge level of the low-voltage battery  42  is higher than or equal to the charge level determined on the basis of the electric power for reprogramming of the update-target device  44  calculated by the high-voltage battery controller  32   a.    
     If it is determined that charging of the low-voltage battery  42  is completed (YES in step S 217 ), the DC-DC converter controller  60   a  of the control device  22  causes the DC-DC converter  60  to stop operating (step S 219 ) and the high-voltage relay controller  34   a  breaks the coupling of the high-voltage relay  34  (step S 221 ). 
     After the coupling of the high-voltage relay  34  is broken in step S 221  or if it is determined in step S 201  that reprogramming can be performed by using the low-voltage battery  42  (YES in step S 201 ), the control device  22  instructs the updater  46  to perform reprogramming. The updater  46  performs reprogramming of the update-target device  44  by using electric power supplied from the low-voltage battery  42  (step S 223 ). If reprogramming ends (YES in step S 225 ), the process ends. 
     The control method of the reprogramming process performed in the vehicle  1  according to the embodiment has been described above. The embodiment provides the following beneficial effects. 
     In the related art, electric power used when reprogramming is performed is commonly supplied by the low-voltage battery  42 . However, for example, when the SOC of the low-voltage battery is low, electric power used for reprogramming may be deficient. If reprogramming is aborted because of a deficiency of electric power, this may adversely affect the normal operation of the vehicle  1 , which may lead to replacement of the update-target device  44  subjected to reprogramming according to circumstances. 
     On the other hand, in the case where reprogramming data is received via wireless communication and reprogramming is performed on the basis of the received reprogramming data, if the vehicle  1  is coupled to an external power supply with a cable, the convenience is reduced. Thus, it is not desirable to supply electric power from an external power supply when reprogramming is performed. 
     Accordingly, it is conceivable to reduce in voltage the output power of the high-voltage battery  32  and use the output power reduced in voltage in reprogramming when electric power of the low-voltage battery  42  used in reprogramming is deficient in an electric-powered vehicle equipped with the high-voltage battery  32  for driving the motor. However, in such a case, it is difficult to perform reprogramming of a certain device relating to electric power supply from the high-voltage battery  32  to the low-voltage system circuit  40 . 
     Accordingly, in the present embodiment, it is determined whether the update-target device  44  is a certain device relating to electric power supply from the high-voltage battery  32  to the low-voltage system circuit  40 . If it is determined that the update-target device  44  is the certain device, the DC-DC converter  60  is caused to reduce in voltage the output electric power of the high-voltage battery  32  and to supply the electric power reduced in voltage to the low-voltage system circuit  40 , so that the low-voltage battery  42  is charged. After the low-voltage battery  42  is charged, the certain device is caused to stop operating. The updater  46  is then caused to perform reprogramming of the certain device by using the output electric power of the low-voltage battery  42 . Consequently, the likelihood of updating of a program being aborted because of a deficiency of electric power can be reduced, and reprogramming of the certain device relating to electric power supply from the high-voltage battery  32  to the low-voltage system circuit  40  can be performed. 
     If it is determined that the update-target device  44  is not the certain device, the DC-DC converter  60  is caused to reduce in voltage the output electric power of the high-voltage battery  32  and to supply the electric power reduced in voltage to the low-voltage system circuit  40 , and the updater  46  is caused to update the program of the update-target device  44  by using the output electric power of the high-voltage battery  32 . Consequently, if the update-target device  44  is not the certain device, charging of the low-voltage battery  42  is omitted. Thus, the time taken for reprogramming can be reduced. 
     As described above, the control device  22  determines whether the charge level of the low-voltage battery  42  is higher than or equal to the electric power level used for reprogramming of the update-target device  44 . If the control device  22  determines that the charge level of the low-voltage battery  42  is not deficient relative to the electric power level used for reprogramming, the control device  22  causes the updater  46  to perform reprogramming of the certain device by using the output electric power of the low-voltage battery  42 . On the other hand, if the control device  22  determines that the charge level of the low-voltage battery  42  is deficient relative to the electric power level used for reprogramming, the control device  22  determines whether the update-target device  44  is the certain device relating to electric power supply from the high-voltage battery  32  to the low-voltage system circuit  40 . Thus, if the charge level of the low-voltage battery  42  is higher than or equal to the electric power level used for reprogramming of the update-target device  44 , charging of the low-voltage battery  42  is omitted. Consequently, the time taken for reprogramming can be reduced. 
     The embodiment of the disclosure has been described above with reference to the accompanying drawings. It is needless to say that the disclosure is not limited to such an embodiment. It is obvious that a person skilled in the art can conceive various alterations and modifications within a scope of the claims. It is to be understood that these alterations and modifications are, of course, included in the technical scope of the disclosure. 
     In the embodiment described above, reprogramming is started upon the user&#39;s confirmation to perform reprogramming. However, the disclosure is not limited to this. For example, when the user confirms reprogramming, the user may designate any timing at which reprogramming is actually performed. In this case, when the current time reaches the timing set by the user, the updater  46  starts reprogramming. If reprogramming is not to be performed because the vehicle  1  is traveling or the like when the current time reaches the timing set by the user, the reprogramming confirmation screen  24   a  may be displayed again to ask for the user&#39;s confirmation after the vehicle  1  is stopped. 
     In the embodiment described above, in the case where the reprogramming information is received and reprogramming is scheduled, the high-voltage battery controller  32   a  changes the target SOC lower-limit value of the high-voltage battery  32  to a value (scheduled reprogramming preparation value) that is higher than the normal value and sets the SOC upper-limit value to the normal value. However, the disclosure is not limited to such an example. The high-voltage battery controller  32   a  may change the target SOC upper-limit value of the high-voltage battery  32  to a value that is higher than the normal value and also change the target SOC lower-limit value of the high-voltage battery  32  to a value (scheduled reprogramming preparation value) that is higher than the normal value. 
     In the embodiment described above, the case where the vehicle  1  is a parallel hybrid vehicle has been described. However, the disclosure is not limited to this. The disclosure is applicable to various vehicles such as an EV, a plug-in hybrid vehicle (PHEV), and a non-plug-in hybrid vehicle (hybrid vehicle). 
     The control device  22  illustrated in  FIG.  1    and the updater  46  illustrated in  FIG.  2    can be implemented by circuitry including at least one semiconductor integrated circuit such as at least one processor (e.g., a central processing unit (CPU)), at least one application specific integrated circuit (ASIC), and/or at least one field programmable gate array (FPGA). At least one processor can be configured, by reading instructions from at least one machine readable tangible medium, to perform all or a part of functions of the control device  22  including the high-voltage battery controller  32   a , the high-voltage relay controller  34   a , the low-voltage battery controller  42   a , the automotive navigation system controller  52   a , the IG power supply controller  54   a , and the DC-DC converter controller  60   a  and to perform all or a part of functions of the updater  46 . Such a medium may take many forms, including, but not limited to, any type of magnetic medium such as a hard disk, any type of optical medium such as a CD and a DVD, any type of semiconductor memory (i.e., semiconductor circuit) such as a volatile memory and a non-volatile memory. The volatile memory may include a DRAM and a SRAM, and the non-volatile memory may include a ROM and an NVRAM. The ASIC is an integrated circuit (IC) customized to perform, and the FPGA is an integrated circuit designed to be configured after manufacturing in order to perform, all or a part of the functions of the modules illustrated in  FIGS.  1  and  2   .