Patent Publication Number: US-2021188108-A1

Title: Vehicle, vehicle control system, and vehicle control method

Description:
INCORPORATION BY REFERENCE 
     The disclosure of Japanese Patent Application No. 2019-229533 filed on Dec. 19, 2019 including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a vehicle, a vehicle control system, and a vehicle control method. 
     2. Description of Related Art 
     Japanese Unexamined Patent Application Publication No. 2019-156007 (JP 2019-156007 A) discloses a control device that controls input power of a secondary battery using a power upper limit value (Win) indicating an upper limit value of the input power of the secondary battery mounted on a vehicle. 
     SUMMARY 
     Electrically driven vehicles (for example, electric vehicles or hybrid vehicles) that use a secondary battery as a power source have spread in recent years. In the electrically driven vehicles, when the capacity or the performance of the secondary battery decreases due to battery deterioration or the like, it is conceivable that the secondary battery mounted on the electrically driven vehicle is replaced. 
     The secondary battery is generally mounted on a vehicle in the form of a battery pack. The battery pack includes a secondary battery, a sensor that detects the state of the secondary battery (for example, current, voltage, and temperature), and a control device. Hereinafter, the control device incorporated in the battery pack may be referred to as “battery electronic control unit (ECU)”, and the sensor incorporated in the battery pack may be referred to as “battery sensor”. Peripheral devices (for example, a sensor and a control device) suitable for the secondary battery are mounted on the battery pack. The battery pack is maintained so that the secondary battery and its peripheral devices can operate normally. Therefore, when replacing the secondary battery mounted on the vehicle, it is considered preferable to replace not only the secondary battery but the entire battery pack mounted on the vehicle from the viewpoint of vehicle maintenance. 
     As described in JP 2019-156007 A, there is a known control device that is mounted on a vehicle separately from a battery pack and that controls the input power of the secondary battery using a power upper limit value (hereinafter, also referred to as “power restricting control device”). The power restricting control device is configured to perform power-based input restriction. The power-based input restriction is a process of controlling the input power of the secondary battery so that the input power of the secondary battery does not exceed the power upper limit value. In general, a vehicle including a control device that performs the power-based input restriction is equipped with a battery pack including a battery ECU that obtains a power upper limit value using a detection value from a battery sensor (hereinafter, also referred to as “power restricting battery pack”). 
     On the other hand, a control device is known that is mounted on a vehicle separately from the battery pack and that controls the input current of the secondary battery by using a current upper limit value that indicates an upper limit value of the input current of the secondary battery (hereinafter, also referred to as “current restricting control device”). The current restricting control device is configured to perform current-based input restriction. The current-based input restriction is a process of controlling the input current of the secondary battery so that the input current of the secondary battery does not exceed the current upper limit value. In general, a vehicle including a control device that performs the current-based input restriction is equipped with a battery pack including a battery ECU that obtains a current upper limit value using a detection value from a battery sensor (hereinafter, also referred to as “current restricting battery pack”). 
     Depending on the situation of supply and demand (or the stock status) of the battery pack, the current restricting battery pack may be more easily available than the power restricting battery pack. However, regarding the vehicle of the related art, it has not been expected to use a current restricting battery pack and a power restricting control device in combination, so no study has been conducted on means for using a current restricting battery pack and a power restricting control device in combination. Thus, it is difficult to adopt a current restricting battery pack in a vehicle equipped with a power restricting control device. 
     The present disclosure provides a vehicle, a vehicle control system, and a vehicle control method that can perform power-based input restriction on a secondary battery included in a current restricting battery pack. 
     A vehicle according to a first aspect of the present disclosure includes a battery pack including a first control device, a second control device provided separately from the battery pack, and a converter. The battery pack further includes a secondary battery and a battery sensor that detects a state of the secondary battery. The first control device is configured to use a detection value of the battery sensor to obtain a current upper limit value indicating an upper limit value of an input current of the secondary battery. The second control device is configured to use a power upper limit value indicating an upper limit value of an input power of the secondary battery to control the input power of the secondary battery. The converter is configured to perform conversion of the current upper limit value into the power upper limit value by performing multiplication of a voltage value of the secondary battery in a state where a current corresponding to the current upper limit value is flowing (hereinafter, referred to as “estimated voltage value”) by the current upper limit value. 
     The vehicle is equipped with the converter that converts the current upper limit value into the power upper limit value. The voltage of the secondary battery changes depending on the magnitude of the current. The converter uses the estimated voltage value (that is, the voltage value of the secondary battery in the state where the current corresponding to the current upper limit value is flowing) to convert the current upper limit value into the power upper limit value. Specifically, the converter converts the current upper limit value into the power upper limit value by multiplying the current upper limit value by the estimated voltage value. This makes it possible to obtain the power upper limit value corresponding to the current upper limit value with high accuracy. According to the above configuration, the second control device can appropriately perform power-based input restriction even when the current restricting battery pack is adopted. The second control device corresponds to the power restricting control device described above. 
     In the above aspect, the converter may be configured to use measured values of a current and a voltage of the secondary battery that are detected by the battery sensor, an internal resistance of the secondary battery, and the current upper limit value to obtain the estimated voltage value. 
     The converter having the above configuration can easily and appropriately obtain the estimated voltage value. Then, the converter can convert the current upper limit value into the power upper limit value with high accuracy using the estimated voltage value obtained as described above. Hereinafter, the measured values of the current and the voltage of the secondary battery that are detected by the battery sensor may be referred to as “actual current” and “actual voltage”. The current, the voltage, and the internal resistance of the secondary battery have a relationship represented by “internal resistance=voltage/current”. The internal resistance of the secondary battery that is used to obtain the estimated voltage value may be stored in advance in a storage device. The internal resistance of the secondary battery stored in the storage device may take a fixed value or may be variable in accordance with the temperature of the secondary battery. The converter described above may obtain the estimated voltage value based on the actual current, the actual voltage, the current upper limit value, and the internal resistance, in accordance with an expression “estimated voltage value=actual voltage+(current upper limit value−actual current)×internal resistance”. 
     In the above aspect, the vehicle may further include a third control device provided separately from the battery pack and configured to relay communication between the first control device and the second control device. The converter may be mounted on the third control device. The battery pack may be configured to output the current upper limit value. The vehicle may be configured such that when the current upper limit value is input from the battery pack to the third control device, the converter performs the conversion of the current upper limit value into the power upper limit value and the power upper limit value is output from the third control device to the second control device. 
     In the above configuration, the third control device provided separately from the battery pack includes the converter, and the converter converts the current upper limit value into the power upper limit value. Thus, the converter can be mounted on the vehicle without a change in the configurations of the battery pack (including the first control device) and the second control device. 
     In the above aspect, the third control device may be configured to perform the conversion and output the power upper limit value when the current upper limit value is input and to output the power upper limit value without performing the conversion when the power upper limit value is input. 
     In the above aspect, when the vehicle is equipped with the current restricting battery pack, the third control device performs the conversion on the current upper limit value input from the current restricting battery pack and outputs the power upper limit value. On the other hand, when the vehicle is equipped with the power restricting battery pack, the third control device outputs the power upper limit value without performing the conversion on the power upper limit value input from the power restricting battery pack. Thus, according to the above configuration, the second control device can appropriately perform the power-based input restriction in both a case where the current restricting battery pack is adopted and a case where the power restricting battery pack is adopted. 
     In the above aspect, each of the first control device, the second control device, and the third control device may be a microcomputer connected to an in-vehicle local area network (LAN). In the in-vehicle LAN, the first control device may be connected to the second control device via the third control device to communicate with the second control device via the third control device. 
     Note that LAN is an abbreviation for “local area network”. In the above aspect, each of the first to third control devices is a microcomputer. The microcomputer has a small size and a high processing capacity, so it is suitable as an in-vehicle control device. The third control device can receive the current upper limit value from the first control device through the in-vehicle LAN, convert the current upper limit value into the power upper limit value with the converter, and then transmit the power upper limit value to the second control device through the in-vehicle LAN. With the above configuration, each control device can suitably perform the required calculation and communication. As the communication protocol of the in-vehicle LAN, a controller area network (CAN) or FlexRay may be adopted. 
     The third control device can also be used for purposes other than the conversion of the upper limit value (that is, conversion from the current upper limit value into the power upper limit value). The third control device may be configured to manage information (for example, accumulate vehicle data). Further, the third control device may function as a central gateway (CGW). 
     In the above aspect, the converter may be mounted on the first control device. The first control device may be configured to perform, with the converter, the conversion of the current upper limit value obtained using the detection value of the battery sensor into the power upper limit value and to output the power upper limit value to the second control device when the first control device is connected to the second control device. 
     The converter may be incorporated in the first control device (that is, inside the battery pack). In this configuration, the current upper limit value can be converted into the power upper limit value inside the battery pack and the power upper limit value can be output from the battery pack. Thus, the second control device can appropriately perform the power-based input restriction without adding the third control device. 
     In the above aspect, the converter may be mounted on the second control device. The battery pack may be configured to output the current upper limit value. The second control device may be configured to perform, with the converter, the conversion of the current upper limit value input from the battery pack into the power upper limit value and to control the input power of the secondary battery such that the input power of the secondary battery does not exceed the power upper limit value. 
     In the above configuration, the second control device provided separately from the battery pack includes the converter, and the converter converts the current upper limit value into the power upper limit value. Therefore, the converter can be mounted on the vehicle without a change in the configuration of the battery pack (including the first control device). Further, the second control device can appropriately perform the power-based input restriction without adding the third control device. 
     The vehicle of the above aspect may be an electrically driven vehicle that travels using electric power stored in the secondary battery in the battery pack. The electrically driven vehicle includes an electric vehicle (EV), a hybrid vehicle (HV), and a plug-in hybrid vehicle (PHV). 
     The vehicle may be a hybrid vehicle including a first motor generator, a second motor generator, and an engine. Electric power may be supplied to each of the first motor generator and the second motor generator from the secondary battery in the battery pack. Each of the engine and the first motor generator may be mechanically connected to drive wheels of the hybrid vehicle via a planetary gear. The planetary gear and the second motor generator may be configured such that drive force output from the planetary gear and drive force output from the second motor generator are combined and transmitted to the drive wheels. The second control device may create a control command for each of the first motor generator, the second motor generator, and the engine so that the input power of the secondary battery does not exceed the power upper limit value. 
     A vehicle control system according to a second aspect of the present disclosure is configured such that a battery pack including a secondary battery and a battery sensor that detects a state of the secondary battery is attached to the vehicle control system. The vehicle control system includes a control unit configured to control an input power of the secondary battery such that the input power of the secondary battery does not exceed a power upper limit value when the battery pack is attached to the vehicle control system, and a conversion unit configured such that when a current upper limit value indicating an upper limit value of an input current of the secondary battery and a detection value of the battery sensor are input from the battery pack, the conversion unit uses the detection value of the battery sensor and the current upper limit value to obtain an estimated voltage value (that is, a voltage value of the secondary battery in a state where a current corresponding to the current upper limit value is flowing) and performs conversion of the current upper limit value into the power upper limit value by performing multiplication of the current upper limit value by the estimated voltage value. 
     In the above aspect, the power upper limit value corresponding to the current upper limit value is obtained by multiplying the current upper limit value by the estimated voltage value. Therefore, even when the current restricting battery pack is adopted, it is possible to appropriately perform the power-based input restriction on the secondary battery included in the current restricting battery pack. 
     A vehicle control method according to a third aspect of the present disclosure includes obtaining, with a vehicle control system to which a battery pack including a secondary battery and a battery sensor that detects a state of the secondary battery is attached, a current upper limit value indicating an upper limit value of an input current of the secondary battery and a detection value of the battery sensor, from the battery pack, obtaining, with the vehicle control system, an estimated voltage value (that is, a voltage value of the secondary battery in a state where a current corresponding to the current upper limit value is flowing) using the detection value of the battery sensor and the current upper limit value, performing, with the vehicle control system, conversion of the current upper limit value into a power upper limit value indicating an upper limit value of an input power of the secondary battery by performing multiplication of the current upper limit value by the estimated voltage value, and controlling, with the vehicle control system, the input power of the secondary battery using the power upper limit value. 
     In the above aspect, the power upper limit value corresponding to the current upper limit value is obtained by multiplying the current upper limit value by the estimated voltage value. Therefore, even when the current restricting battery pack is adopted, it is possible to appropriately perform the power-based input restriction on the secondary battery included in the current restricting battery pack. 
     The above configuration makes it possible to provide a vehicle, a vehicle control system, and a vehicle control method that can perform power-based input restriction on a secondary battery included in a current restricting battery pack. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG. 1  is a diagram showing a configuration of a vehicle according to an embodiment of the present disclosure; 
         FIG. 2  is a diagram showing a connection mode of control devices included in the vehicle according to the embodiment of the present disclosure; 
         FIG. 3  is a diagram showing an example of a map used to set a target battery power in the vehicle according to the embodiment of the present disclosure; 
         FIG. 4  is a diagram showing a detailed configuration of a battery pack, a gateway electronic control unit (ECU), and a hybrid vehicle (HV) ECU shown in  FIG. 1 ; 
         FIG. 5  is a diagram showing a detailed configuration of a conversion unit shown in  FIG. 4 ; 
         FIG. 6  is a diagram for describing a method of obtaining an estimated voltage value according to the embodiment of the present disclosure; 
         FIG. 7  is a diagram showing a first example of a vehicle control system according to the embodiment of the present disclosure; 
         FIG. 8  is a diagram showing a second example of the vehicle control system according to the embodiment of the present disclosure; 
         FIG. 9  is a diagram showing a modified example of the gateway ECU shown in  FIG. 4 ; 
         FIG. 10  is a diagram showing a modified example of the HV ECU shown in  FIG. 4 ; 
         FIG. 11  is a diagram showing a first modified example of the vehicle control system shown in  FIG. 4 ; and 
         FIG. 12  is a diagram showing a second modified example of the vehicle control system shown in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present disclosure will be described in detail with reference to the drawings. It should be noted that the same or corresponding parts in the drawings are denoted by the same reference characters and repetitive description thereof will be omitted. Hereinafter, an electronic control unit is also referred to as “ECU”. 
       FIG. 1  is a diagram showing a configuration of a vehicle according to the present embodiment. In the present embodiment, a front-wheel drive four-wheel vehicle (more specifically, a hybrid vehicle) is assumed to be used, but the number of wheels and the drive system can be changed as appropriate. For example, the drive system may be four-wheel drive. 
     Referring to  FIG. 1 , a vehicle  100  is equipped with a battery pack  10  including a battery ECU  13 . Further, a motor ECU  23 , an engine ECU  33 , an HV ECU  50 , and a gateway ECU  60  are mounted on the vehicle  100  separately from the battery pack  10 . The motor ECU  23 , the engine ECU  33 , the HV ECU  50 , and the gateway ECU  60  are located outside the battery pack  10 . The battery ECU  13  is located inside the battery pack  10 . In the present embodiment, the battery ECU  13 , the HV ECU  50 , and the gateway ECU  60  correspond to examples of a “first control device”, a “second control device”, and a “third control device” according to the present disclosure, respectively. 
     The battery pack  10  includes a battery  11 , a voltage sensor  12   a , a current sensor  12   b , a temperature sensor  12   c , the battery ECU  13 , and a system main relay (SMR)  14 . The battery  11  functions as a secondary battery. In the present embodiment, an assembled battery including a plurality of electrically connected lithium ion batteries is adopted as the battery  11 . Each secondary battery that constitutes the assembled battery is also referred to as a “cell”. In the present embodiment, each lithium ion battery that constitutes the battery  11  corresponds to the “cell”. The secondary battery included in the battery pack  10  is not limited to the lithium ion battery and may be another secondary battery (for example, a nickel metal hydride battery). An electrolytic solution secondary battery or an all-solid-state secondary battery may be used as the secondary battery. 
     The voltage sensor  12   a  detects the voltage of each cell of the battery  11 . The current sensor  12   b  detects current flowing through the battery  11  (the charging side takes a negative value). The temperature sensor  12   c  detects the temperature of each cell of the battery  11 . The sensors output the detection results to the battery ECU  13 . The current sensor  12   b  is provided in the current path of the battery  11 . In the present embodiment, one voltage sensor  12   a  and one temperature sensor  12   c  are provided for each cell. However, the present disclosure is not limited to this, and one voltage sensor  12   a  and one temperature sensor  12   c  may be provided for each set of multiple cells, or only one voltage sensor  12   a  and one temperature sensor  12   c  may be provided for one assembled battery. Hereinafter, the voltage sensor  12   a , the current sensor  12   b , and the temperature sensor  12   c  are collectively referred to as “battery sensor  12 ”. The battery sensor  12  may be a battery management system (BMS) that has a state of charge (SOC) estimation function, a state of health (SOH) estimation function, a cell voltage equalization function, a diagnostic function, and a communication function in addition to the above sensor functions. 
     The SMR  14  is configured to switch connection and disconnection of power paths connecting external connection terminals T 1  and T 2  of the battery pack  10  and the battery  11 . For example, an electromagnetic mechanical relay can be used as the SMR  14 . In the present embodiment, a power control unit (PCU)  24  is connected to the external connection terminals T 1  and T 2  of the battery pack  10 . The battery  11  is connected to the PCU  24  via the SMR  14 . When the SMR  14  is in the closed state (connected state), power can be transmitted between the battery  11  and the PCU  24 . In contrast, when the SMR  14  is in the open state (disconnected state), the power paths connecting the battery  11  and the PCU  24  are disconnected. In the present embodiment, the SMR  14  is controlled by the battery ECU  13 . The battery ECU  13  controls the SMR  14  according to an instruction from the HV ECU  50 . The SMR  14  is in the closed state (connected state) when the vehicle  100  is traveling, for example. 
     The vehicle  100  includes an engine  31 , a first motor generator  21   a  (hereinafter referred to as “MG  21   a ”), and a second motor generator  21   b  (hereinafter referred to as “MG  21   b ”) as power sources for traveling. The MG  21   a  and the MG  21   b  are motor generators that have both a function as a motor that outputs torque by receiving drive power and a function as a generator that generates electric power by receiving the torque. An alternating current (AC) motor (for example, a permanent magnet synchronous motor or an induction motor) is used as the MG  21   a  and the MG  21   b . The MG  21   a  and the MG  21   b  are electrically connected to the battery  11  via the PCU  24 . The MG  21   a  has a rotor shaft  42   a  and the MG  21   b  has a rotor shaft  42   b . The rotor shaft  42   a  corresponds to a rotation shaft of the MG  21   a , and the rotor shaft  42   b  corresponds to a rotation shaft of the MG  21   b.    
     The vehicle  100  further includes a single-pinion planetary gear  42 . An output shaft  41  of the engine  31  and the rotor shaft  42   a  of the MG  21   a  are connected to the planetary gear  42 . The engine  31  is, for example, a spark-ignition internal combustion engine including a plurality of cylinders (for example, four cylinders). The engine  31  combusts fuel in each cylinder to generate drive force, and the generated drive force rotates a crankshaft (not shown) shared by all the cylinders. The crankshaft of the engine  31  is connected to the output shaft  41  via a torsional damper (not shown). The output shaft  41  rotates along with rotation of the crankshaft. The engine  31  is not limited to a gasoline engine and may be a diesel engine. 
     The planetary gear  42  has three rotating elements, namely, an input element, an output element, and a reaction force element. More specifically, the planetary gear  42  includes a sun gear, a ring gear that is arranged coaxially with the sun gear, a pinion gear that meshes with the sun gear and the ring gear, and a carrier that holds the pinion gear so that the pinion gear can rotate and revolve. The carrier corresponds to the input element, the ring gear corresponds to the output element, and the sun gear corresponds to the reaction force element. 
     The engine  31  and the MG  21   a  are mechanically connected to each other via the planetary gear  42 . The output shaft  41  of the engine  31  is connected to the carrier of the planetary gear  42 . The rotor shaft  42   a  of the MG  21   a  is connected to the sun gear of the planetary gear  42 . The torque output from the engine  31  is input to the carrier. The planetary gear  42  is configured to divide the torque output from the engine  31  to the output shaft  41  into torque that is transmitted to the sun gear (eventually the MG  21   a ) and torque that is transmitted to the ring gear. When the torque output from engine  31  is output to the ring gear, reaction torque generated by the MG  21   a  acts on the sun gear. 
     The planetary gear  42  and the MG  21   b  are configured such that the drive force output from the planetary gear  42  (that is, drive force output to the ring gear) and the drive force output from the MG  21   b  (that is, drive force output to the rotor shaft  42   b ) are combined and transmitted to the drive wheels  45   a  and  45   b . More specifically, an output gear (not shown) that meshes with a driven gear  43  is attached to the ring gear of the planetary gear  42 . A drive gear (not shown) attached to the rotor shaft  42   b  of the MG  21   b  also meshes with the driven gear  43 . The driven gear  43  combines the torque output from the MG  21   b  to the rotor shaft  42   b  and the torque output from the ring gear of the planetary gear  42 . The drive torque thus combined is transmitted to a differential gear  44  and further transmitted to the drive wheels  45   a  and  45   b  via drive shafts  44   a  and  44   b  extending from the differential gear  44  to the right and left. 
     The MG  21   a  is provided with a motor sensor  22   a  that detects the state (for example, current, voltage, temperature, and rotation speed) of the MG  21   a . The MG  21   b  is provided with a motor sensor  22   b  that detects the state (for example, current, voltage, temperature, and rotation speed) of the MG  21   b . The motor sensors  22   a  and  22   b  output their detection results to the motor ECU  23 . The engine  31  is provided with an engine sensor  32  that detects the state of the engine  31  (for example, intake air amount, intake pressure, intake temperature, exhaust pressure, exhaust temperature, catalyst temperature, engine coolant temperature, and engine speed). The engine sensor  32  outputs its detection result to the engine ECU  33 . 
     The HV ECU  50  is configured to output a command (control command) for controlling the engine  31  to the engine ECU  33 . The engine ECU  33  is configured to control various actuators of the engine  31  (for example, a throttle valve, an ignition device, and an injector (not shown)) in accordance with the command from the HV ECU  50 . The HV ECU  50  can perform engine control through the engine ECU  33 . 
     The HV ECU  50  is configured to output a command (control command) for controlling each of the MG  21   a  and the MG  21   b  to the motor ECU  23 . The motor ECU  23  is configured to generate current signals (for example, signals indicating the magnitude and the frequency of the current) that match the target torque of each of the MG  21   a  and the MG  21   b  in accordance with the command from the HV ECU  50 , and output the generated current signals to the PCU  24 . The HV ECU  50  can perform motor control through the motor ECU  23 . 
     The PCU  24  includes, for example, two inverters each corresponding to the MG  21   a  and the MG  21   b  and a converter (not shown) arranged between each inverter and the battery  11 . The PCU  24  is configured to supply power accumulated in the battery  11  to each of the MG  21   a  and the MG  21   b , and supply electric power generated by each of the MG  21   a  and the MG  21   b  to the battery  11 . The PCU  24  is configured such that the states of the MG  21   a  and the MG  21   b  can be controlled separately, and, for example, the MG  21   b  can be in the power running state while the MG  21   a  is in the regenerative state (that is, the power generation state). The PCU  24  is configured to be able to supply the electric power generated by one of the MG  21   a  and the MG  21   b  to the other. The MG  21   a  and the MG  21   b  are configured to be able to transmit and receive power to and from each other. 
     The vehicle  100  is configured to perform hybrid vehicle (HV) traveling and electric vehicle (EV) traveling. The HV traveling is traveling performed by operating the engine  31  and the MG  21   b  with the engine  31  generating driving force for travel. The EV traveling is traveling performed by operating the MG  21   b  with the engine  31  stopped. When the engine  31  is stopped, combustion is not performed in the cylinders. When the combustion in the cylinders is stopped, the engine  31  does not generate combustion energy (the driving force for travel). The HV ECU  50  is configured to switch between the EV traveling and the HV traveling depending on the situation. 
       FIG. 2  is a diagram showing a connection mode of the control devices included in the vehicle  100  according to the present embodiment. Referring to  FIG. 2  together with  FIG. 1 , the vehicle  100  includes an in-vehicle local area network (LAN) including a local bus B 1  and a global bus B 2 . The control devices (for example, the battery ECU  13 , the motor ECU  23 , and the engine ECU  33 ) mounted on the vehicle  100  is connected to the in-vehicle LAN. In the present embodiment, a controller area network (CAN) is employed as a communication protocol of the in-vehicle LAN. The local bus B 1  and the global bus B 2  are, for example, CAN buses. However, the communication protocol of the in-vehicle LAN is not limited to the CAN, and may be any protocol such as FlexRay. 
     The battery ECU  13 , the motor ECU  23 , and the engine ECU  33  are connected to the local bus B 1 . Although not shown, a plurality of control devices is connected to the global bus B 2 . The control devices connected to global bus B 2  include, for example, a human machine interface (HMI) control device. Examples of the HMI control device include a control device that controls a navigation system or a meter panel. The global bus B 2  is connected to another global bus via a central gateway (CGW) not shown. 
     The HV ECU  50  is connected to the global bus B 2 . The HV ECU  50  is configured to perform CAN communication with each control device connected to the global bus B 2 . The HV ECU  50  is connected to the local bus B 1  via the gateway ECU  60 . The gateway ECU  60  is configured to relay communication between the HV ECU  50  and each control device (for example, the battery ECU  13 , the motor ECU  23 , and the engine ECU  33 ) that is connected to the local bus B 1 . The HV ECU  50  is configured to mutually perform CAN communication with each control device connected to the local bus B 1  via the gateway ECU  60 . The gateway ECU  60  may be configured to collect and save data related to the vehicle  100  (for example, various pieces of information obtained by in-vehicle sensors, and IWin, IWout, Win, Wout and control commands S M1 , S M2 , S E  described later). Further, the gateway ECU  60  may have a firewall function. The gateway ECU  60  may be configured to detect unauthorized communication in cooperation with at least one of the firewall function and an error detection function of the CAN communication. 
     In the present embodiment, a microcomputer is used as the battery ECU  13 , the motor ECU  23 , the engine ECU  33 , the HV ECU  50 , and the gateway ECU  60 . The battery ECU  13  includes a processor  13   a , a random access memory (RAM)  13   b , a storage device  13   c , and a communication interface (I/F)  13   d . The motor ECU  23  includes a processor  23   a , a RAM  23   b , a storage device  23   c , and a communication I/F  23   d . The engine ECU  33  includes a processor  33   a , a RAM  33   b , a storage device  33   c , and a communication I/F  33   d . The HV ECU  50  includes a processor  50   a , a RAM  50   b , a storage device  50   c , and a communication I/F  50   d . The gateway ECU  60  includes a processor  60   a , a RAM  60   b , a storage device  60   c , and a communication I/F  60   d . A central processing unit (CPU), for example, can be used as the processors. Each communication I/F includes a CAN controller. Each RAM functions as a working memory that temporarily stores data processed by the processor. Each storage device is configured to be able to save stored information. Each storage device includes, for example, a read-only memory (ROM) and a rewritable nonvolatile memory. Each storage device stores, in addition to a program, information that is used in the program (for example, a map, a mathematical expression, and various parameters). Various controls of the vehicle  100  are executed when the processors execute the programs stored in the storage devices. However, the present disclosure is not limited to this, and various controls may be executed by dedicated hardware (electronic circuit). The number of processors included in each ECU is not limited, and any ECU may include a plurality of processors. 
     Charge/discharge control of the battery  11  will be described referring to  FIG. 1  again. Hereinafter, the input power of the battery  11  and the output power of the battery  11  are collectively referred to as “battery power”. The HV ECU  50  determines target battery power using the SOC of the battery  11 . Then, the HV ECU  50  controls charge/discharge of the battery  11  so that the battery power becomes closer to the target battery power. However, such charge/discharge control of the battery  11  is restricted by input/output restriction described later. Hereinafter, the target battery power on the charging side (input side) may be referred to as “target input power”, and the target battery power on the discharging side (output side) may be referred to as “target output power”. In the present embodiment, the power on the discharging side is represented by a positive (+) value and the power on the charging side is represented by a negative (−) value. However, when comparing the magnitude of the power, the absolute value is used regardless of the positive or negative sign (+/−). That is, the magnitude of the power is smaller as the value becomes closer to zero. When an upper limit value and a lower limit value are set for the power, the upper limit value is located on the side where the absolute value of the power is large, and the lower limit value is located on the side where the absolute value of the power is small. The power exceeding the upper limit value on the positive side means that the power becomes larger on the positive side than the upper limit value (that is, the power moves away to the positive side with respect to zero). The power exceeding the upper limit value on the negative side means that the power becomes larger on the negative side than the upper limit value (that is, the power moves away to the negative side with respect to zero). The SOC indicates the remaining charge amount and, for example, the ratio of the current charge amount to the charge amount in the fully charged state is represented by a range between 0% and 100%. As the measuring method of the SOC, a known method such as a current integration method or an open circuit voltage (OCV) estimation method can be adopted. 
       FIG. 3  is a diagram showing an example of a map used for determining the target battery power. In  FIG. 3 , a reference value C 0  indicates a control center value of the SOC, a power value P A  indicates a maximum value of the target input power, and a power value P B  indicates a maximum value of the target output power. Referring to  FIG. 3  together with  FIG. 1 , according to this map, when the SOC of the battery  11  is the reference value C 0 , the target battery power is “0”, and the battery  11  is neither charged nor discharged. In the region where the SOC of the battery  11  is smaller than the reference value C 0  (excessive discharge region), the target input power is larger as the SOC of the battery  11  is smaller until the target input power reaches the maximum value (power value P A ). In contrast, in a region where the SOC of the battery  11  is larger than the reference value C 0  (overcharge region), the target output power is larger as the SOC of the battery  11  is larger until the target output power reaches the maximum value (power value P B ). The HV ECU  50  determines the target battery power in accordance with the map shown in  FIG. 3 , and charges and discharges the battery  11  so that the battery power becomes closer to the determined target battery power, thereby bringing the SOC of the battery  11  closer to the reference value C 0 . The reference value C 0  of the SOC may be a fixed value or may be variable depending on the situation of the vehicle  100 . 
     The HV ECU  50  is configured to perform input restriction and output restriction of the battery  11 . The HV ECU  50  sets a first power upper limit value (hereinafter, referred to as “Win”) indicating an upper limit value of the input power of the battery  11  and a second power upper limit value (hereinafter, referred to as “Wout”) indicating an upper limit value of the output power of the battery  11 , and controls battery power such that the battery power does not exceed the set Win and Wout. The HV ECU  50  adjusts the battery power by controlling the engine  31  and the PCU  24 . When Win or Wout is smaller (that is, closer to zero) than the target battery power, the battery power is controlled to Win or Wout instead of the target battery power. In the present embodiment, Win corresponds to an example of the “power upper limit value” according to the present disclosure. 
     The battery ECU  13  is configured to use a detection value of the battery sensor  12  to obtain a first current upper limit value (hereinafter, also referred to as “IWin”) indicating an upper limit value of the input current of the battery  11 . The battery ECU  13  is also configured to use a detection value of the battery sensor  12  to obtain a second current upper limit value (hereinafter, also referred to as “IWout”) indicating an upper limit value of the output current of the battery  11 . That is, the battery pack  10  corresponds to a current restricting battery pack. On the other hand, the HV ECU  50  is configured to use Win to control the input power of the battery  11 . The HV ECU  50  is configured to perform power-based input restriction (that is, a process of controlling the input power of the battery  11  so that the input power of the battery  11  does not exceed Win). Further, the HV ECU  50  is configured to use Wout to control the output power of the battery  11 . The HV ECU  50  is configured to perform power-based output restriction (that is, a process of controlling the output power of the battery  11  so that the output power of the battery  11  does not exceed Wout). That is, the HV ECU  50  corresponds to a power restricting control device. In the present embodiment, IWin corresponds to an example of the “current upper limit value” according to the present disclosure. 
     As described above, the vehicle  100  includes the current restricting battery pack (that is, the battery pack  10 ) and the power restricting control device (that is, the HV ECU  50 ). In the vehicle  100 , the current restricting battery pack and the power restricting control device are used in combination. IWin and IWout are output from the battery pack  10 , and IWin and IWout are respectively converted into Win and Wout by the gateway ECU  60  interposed between the battery pack  10  and the HV ECU  50 . Thereby, Win and Wout are input to the HV ECU  50 . With this configuration, the HV ECU  50  can appropriately perform power-based input restriction and power-based output restriction on the battery  11  included in the battery pack  10 . 
       FIG. 4  is a diagram showing a detailed configuration of the battery pack  10 , the gateway ECU  60 , and the HV ECU  50 . S 1  and S 4  in  FIG. 4  indicate a first step and a fourth step, respectively, which will be described later. Referring to  FIG. 4  together with  FIG. 2 , in the present embodiment, the battery  11  included in the battery pack  10  is an assembled battery including a plurality of cells  111 . Each cell  111  is, for example, a lithium ion battery. Each cell  111  includes a positive electrode terminal  111   a , a negative electrode terminal  111   b , and a battery case  111   c . The voltage between the positive electrode terminal  111   a  and the negative electrode terminal  111   b  corresponds to a cell voltage Vs. In the battery  11 , the positive electrode terminal  111   a  of one cell  111  and the negative electrode terminal  111   b  of another cell  111  adjacent to the one cell  111  are electrically connected to each other by a bus bar  112  having conductivity. The cells  111  are connected to each other in series. However, the present disclosure is not limited to this, and any connection mode may be adopted in the assembled battery. 
     The battery pack  10  includes the battery sensor  12 , the battery ECU  13 , and the SMR  14  in addition to the battery  11 . Signals output from the battery sensor  12  to the battery ECU  13  (hereinafter, also referred to as “battery sensor signals”) include a voltage signal VB output from the voltage sensor  12   a , a current signal IB output from the current sensor  12   b , and a temperature signal TB output from the temperature sensor  12   c . The voltage signal VB indicates a measured value of the voltage of each cell  111  (cell voltage Vs). The current signal IB indicates a measured value of the current flowing through the battery  11  (the charging side takes a negative value). The temperature signal TB indicates a measured value of the temperature of each cell  111 . 
     The battery ECU  13  repeatedly obtains the latest battery sensor signals. The interval at which the battery ECU  13  obtains the battery sensor signals (hereinafter also referred to as “sampling cycle”) may be a fixed value or may be variable. In the present embodiment, the sampling cycle is 8 ms. However, the present disclosure is not limited to this, and the sampling cycle may be variable within a predetermined range (for example, a range from 1 ms to 1 s). Hereinafter, the number of times the battery ECU  13  obtains the battery sensor signals per unit time may be referred to as “sampling rate”. There is a tendency that the higher the sampling rate is, the higher the accuracy of obtaining Win and Wout (that is, conversion accuracy) through the conversion process described later is. 
     The battery ECU  13  includes an IWin calculation unit  131  and an IWout calculation unit  132 . The IWin calculation unit  131  is configured to use the detection value of the battery sensor  12  (that is, the battery sensor signals) to obtain IWin. A known method can be used as the calculation method of IWin. The Win calculation unit  131  may determine IWin so that charge current restriction is performed to protect the battery  11 . IWin may be determined to suppress overcharge, Li deposition, high rate of deterioration, and battery overheating in the battery  11 , for example. The IWout calculation unit  132  is configured to use the detection value of the battery sensor  12  (that is, the battery sensor signals) to obtain IWout. A known method can be used as the calculation method of IWout. The IWout calculation unit  132  may determine IWout so that discharge current restriction is performed to protect the battery  11 . IWout may be determined to suppress overdischarge, Li deposition, high rate of deterioration, and battery overheating in the battery  11 , for example. In the battery ECU  13 , for example, the IWin calculation unit  131  and the IWout calculation unit  132  are implemented by the processor  13   a  shown in  FIG. 2  and the program executed by the processor  13   a . However, the present disclosure is not limited to this, and the IWin calculation unit  131  and the IWout calculation unit  132  may be implemented by dedicated hardware (electronic circuit). 
     The battery pack  10  outputs IWin calculated by the IWin calculation unit  131 , IWout calculated by the IWout calculation unit  132 , and the signals obtained from the battery sensor  12  (that is, the battery sensor signals) to the gateway ECU  60 . These pieces of information are output from the battery ECU  13  included in the battery pack  10  to the gateway ECU  60  provided outside the battery pack  10 . As shown in  FIG. 2 , the battery ECU  13  and the gateway ECU  60  exchange information through CAN communication. 
     The gateway ECU  60  includes a conversion unit  600  described below.  FIG. 5  is a diagram showing a detailed configuration of the conversion unit  600 . S 2  and S 3  in  FIG. 5  indicate a second step and a third step, respectively, which will be described later. Referring to  FIG. 5  together with  FIG. 4 , the conversion unit  600  includes a first estimation unit  611 , a second estimation unit  621 , and calculation units  612  and  622 . In the gateway ECU  60 , for example, the conversion unit  600  (and therefore the first estimation unit  611 , the second estimation unit  621 , and the calculation units  612  and  622 ) is implemented by the processor  60   a  shown in  FIG. 2  and the program executed by the processor  60   a . However, the present disclosure is not limited to this, and the conversion unit  600  may be implemented by dedicated hardware (electronic circuit). The conversion unit  600  according to the present embodiment corresponds to an example of a “converter” according to the present disclosure. 
     The first estimation unit  611  estimates a voltage value (hereinafter, referred to as “V 1 ”) of the battery  11  in a state where a current corresponding to IWin is flowing. V 1  according to the present embodiment corresponds to an example of an “estimated voltage value” according to the present disclosure. In addition, the second estimation unit  621  estimates a voltage value (hereinafter, referred to as “V 2 ”) of the battery  11  in a state where a current corresponding to IWout is flowing. 
       FIG. 6  is a diagram for describing the method of estimating V 1  with the first estimation unit  611 . Referring to  FIG. 6  together with  FIG. 5 , the first estimation unit  611  uses the actual current and the actual voltage of the battery  11  (that is, the measured values of the current and the voltage of the battery  11  detected by the battery sensor  12 ), the internal resistance of the battery  11 , and IWin to obtain V 1 . A graph M 1  in  FIG. 6  shows the following relational expression. 
         V 1= VBs −( IW in− IB )× R  
 
     In the above relational expression, “R” indicates the internal resistance, “IB” indicates the actual current, and “VBs” indicates the actual voltage. In the present embodiment, the average cell voltage (for example, the average value of the voltages of all the cells  111 ) is adopted as VBs. However, the present disclosure is not limited to this. Instead of the average cell voltage, the maximum cell voltage (that is, the highest voltage value among the voltages of the cells  111 ), the minimum cell voltage (that is, the lowest voltage value among the voltages of the cells  111 ), or the inter-terminal voltage of the assembled battery (that is, the voltage applied between the external connection terminals T 1  and T 2  when the SMR  14  is in the closed state) may be adopted as VBs. The first estimation unit  611  can obtain VBs using the battery sensor signals (particularly, the voltage signal VB). The above relational expression is stored in the storage device  60   c  ( FIG. 2 ) in advance. The above relational expression may include a predetermined correction term (for example, a correction term regarding polarization). 
     In the present embodiment, the first estimation unit  611  refers to a map M 2  to obtain the internal resistance of the battery  11 . In the map M 2 , “R” indicates the internal resistance and “TB” indicates the temperature of the battery  11 . The map M 2  is information indicating the relationship between the temperature (TB) of the battery  11  and the internal resistance (R) of the battery  11 , and is stored in the storage device  60   c  ( FIG. 2 ) in advance. The first estimation unit  611  can obtain the internal resistance of the battery  11  from the temperature of the battery  11 . The temperature of the battery  11  used to obtain the internal resistance is, for example, a measured value of the temperature of the battery  11  detected by the temperature sensor  12   c . For example, any one of an average cell temperature, a maximum cell temperature, and a minimum cell temperature may be adopted as the temperature of the battery  11 . As shown in the map M 2 , the internal resistance of the battery  11  tends to decrease as the temperature of the battery  11  increases. The first estimation unit  611  may periodically detect the actual current and the actual voltage, and correct the map M 2  based on the relationship between the actual current and the actual voltage. 
     The method of estimating V 1  with the first estimation unit  611  has been described above with reference to  FIG. 6 . V 2  is also estimated by a method similar to the above-described method of estimating V 1 . The second estimation unit  621  estimates V 2  in accordance with the following relational expression. Since the method of estimating V 2  with the second estimation unit  621  is basically the same as the method of estimating V 1  described above, only the relational expression is shown and the detailed description is omitted. 
         V 2= VBs +( IW out− IB )× R  
 
     Referring again to  FIG. 4  and  FIG. 5 , the calculation unit  612  uses V 1  obtained by the first estimation unit  611  to convert IWin into Win. More specifically, the calculation unit  612  converts IWin into Win by performing the calculation represented by the following expression F1. The expression F1 is stored in advance in the storage device  60   c  ( FIG. 2 ). 
         W in= IW in× V 1  (F1)
 
     The calculation unit  612  receives V 1  from the first estimation unit  611  and multiplies IWin input from the battery pack  10  ( FIG. 4 ) by V 1 . In this way, the calculation unit  612  converts IWin into Win by multiplying IWin by V 1  in accordance with the above expression F1. 
     The calculation unit  622  uses V 2  obtained by the second estimation unit  621  to convert IWout into Wout. More specifically, the calculation unit  622  converts IWout into Wout by performing the calculation represented by the following expression F2. The expression F2 is stored in advance in the storage device  60   c  ( FIG. 2 ). 
         W out= IW out× V 2  (F2)
 
     The calculation unit  622  receives V 2  from the second estimation unit  621  and multiplies IWout input from the battery pack  10  ( FIG. 4 ) by V 2 . In this way, the calculation unit  622  converts IWout into Wout by multiplying IWout by V 2  in accordance with the above expression F2. 
     Referring to  FIG. 4 , when IWin, IWout, and the battery sensor signals are input from the battery pack  10  to the gateway ECU  60 , the conversion unit  600  of the gateway ECU  60  (see  FIG. 5  for the detailed configuration) converts IWin and IWout into Win and Wout, respectively. Then, Win, Wout, and the battery sensor signals are output from the gateway ECU  60  to the HV ECU  50 . The gateway ECU  60  sequentially obtains IWin, IWout, and VBs from the battery pack  10  in real time, calculates Win and Wout, and transmits Win and Wout to the HV ECU  50 . Win and Wout transmitted from the gateway ECU  60  to the HV ECU  50  are sequentially updated using the latest IWin, IWout, and VBs (that is, real-time values). As shown in  FIG. 2 , the gateway ECU  60  and the HV ECU  50  exchange information through CAN communication. 
     The HV ECU  50  includes a control unit  51  described below. In the HV ECU  50 , for example, the control unit  51  is implemented by the processor  50   a  shown in  FIG. 2  and the program executed by the processor  50   a . However, the present disclosure is not limited to this, and the control unit  51  may be implemented by dedicated hardware (electronic circuit). 
     The control unit  51  is configured to use Win to control the input power of the battery  11 . Further, the control unit  51  is configured to use Wout to control the output power of the battery  11 . In the present embodiment, the control unit  51  creates the control commands S M1 , S M2 , and S E  for the MG  21   a , MG  21   b , and the engine  31  shown in  FIG. 1 , respectively, so that the input power and the output power of the battery  11  do not exceed Win and Wout, respectively. The control unit  51  outputs the control commands S M1  and S M2  for the MG  21   a  and the MG  21   b  to the motor ECU  23 , and outputs the control command S E  for the engine  31  to the engine ECU  33 . The control commands S M1  and S M2  output from the HV ECU  50  are sent to the motor ECU  23  through the gateway ECU  60 . The motor ECU  23  controls the PCU  24  ( FIG. 1 ) in accordance with the received control commands S M1  and S M2 . The control command S E  output from the HV ECU  50  is sent to the engine ECU  33  through the gateway ECU  60 . The engine ECU  33  controls the engine  31  in accordance with the received control command S E . The MG  21   a , the MG  21   b , and the engine  31  are controlled in accordance with the control commands S M1 , S M2 , and S E , so that the input power and the output power of the battery  11  are controlled so as not to exceed Win and Wout, respectively. The HV ECU  50  can adjust the input power and the output power of the battery  11  by controlling the engine  31  and the PCU  24 . The HV ECU  50  sequentially obtains Win and Wout from the gateway ECU  60  in real time, creates the control commands S M1 , S M2 , and S E  using the latest Win and Wout (that is, real-time values), and transmits the control commands S M1 , S M2 , and S E t the motor ECU  23  and the engine ECU  33 . 
     As described above, the vehicle  100  according to the present embodiment includes the battery pack  10  including the battery ECU  13 , and the HV ECU  50  and the gateway ECU  60  that are provided separately from the battery pack  10 . The gateway ECU  60  is configured to relay communication between the battery ECU  13  and the HV ECU  50 . The conversion unit  600  is included in the gateway ECU  60 . The conversion unit  600  converts IWin into Win by multiplying V 1  (that is, the voltage value of the battery  11  in the state where the current corresponding to IWin is flowing) by IWin. The conversion unit  600  converts IWout into Wout by multiplying V 2  (that is, the voltage value of the battery  11  in the state where the current corresponding to IWout is flowing) by IWout. The battery ECU  13  is configured to use the detection value of the battery sensor  12  to obtain IWin (that is, the current upper limit value indicating the upper limit value of the input current of the battery  11 ) and IWout (that is, the current upper limit value indicating the upper limit value of the output current of the battery  11 ). The battery pack  10  is configured to output IWin and IWout. When IWin and IWout are input from the battery pack  10  to the gateway ECU  60 , the conversion unit  600  of the gateway ECU  60  converts IWin and IWout into Win and Wout, respectively, and the gateway ECU  60  outputs Win and Wout to the HV ECU  50 . The HV ECU  50  is configured to control the input power of the battery  11  using Win (that is, the power upper limit value indicating the upper limit value of the input power of the battery  11 ). Further, the HV ECU  50  is configured to control the output power of the battery  11  using Wout (that is, the power upper limit value indicating the upper limit value of the output power of the battery  11 ). 
     Since the vehicle  100  includes the conversion unit  600 , IWin and IWout output from the current restricting battery pack (for example, the battery pack  10 ) can be converted into Win and Wout, respectively. Although the voltage of the battery  11  changes depending on the magnitude of the current, the conversion unit  600  can obtain Win and Wout corresponding to IWin and IWout with high accuracy by multiplying IWin and IWout by V 1  and V 2 , respectively. The HV ECU  50  can appropriately perform the power-based input restriction and the power-based output restriction using Win and Wout thus obtained. 
     The control parts included in the vehicle  100  may be modularized in predetermined units to form a vehicle control system. 
       FIG. 7  is a diagram showing a first example of the vehicle control system. Referring to  FIG. 7 , a vehicle control system  201  includes the MGs  21   a  and  21   b , the motor sensors  22   a  and  22   b , the motor ECU  23 , the PCU  24 , the engine  31 , the engine sensor  32 , the engine ECU  33 , the planetary gear  42 , the HV ECU  50 , and the gateway ECU  60  that are modularized. The vehicle control system  201  is configured so that the battery pack  10  ( FIG. 4 ) can be attached. 
       FIG. 8  is a diagram showing a second example of the vehicle control system. Referring to  FIG. 8 , a vehicle control system  202  is configured by modularizing the control parts of the vehicle control system  201 , excluding the engine control parts (that is, the engine  31 , the engine sensor  32 , and the engine ECU  33 ). The vehicle control system  202  is configured so that the battery pack  10  ( FIG. 4 ) and the engine control parts can be attached. 
     The modularized vehicle control system can be treated as one component. Modularization of the control parts as described above facilitates manufacture of the vehicle. Modularization also enables parts to be shared between different vehicle models. 
     The vehicle control systems  201  and  202  each include the HV ECU  50  and the gateway ECU  60 . When the battery pack  10  ( FIG. 4 ) is attached to each of the vehicle control systems  201  and  202 , the HV ECU  50  controls the input power of the battery  11  so that the input power of the battery  11  does not exceed Win and controls the output power of the battery  11  so that the output power of the battery  11  does not exceed Wout. In the vehicle control system  201 ,  202 , the HV ECU  50  corresponds to an example of the “control unit” according to the present disclosure. When IWin is input from the battery pack  10 , the gateway ECU  60  uses the detection value (for example, voltage, current, and temperature) of the battery sensor  12  and IWin to obtain V 1 , and multiplies Win by V 1  to convert IWin into Win. Further, when IWout is input from the battery pack  10 , the gateway ECU  60  uses the detection value (for example, voltage, current, and temperature) of the battery sensor  12  and IWout to obtain V 2 , and multiplies IWout by V 2  to convert IWout into Wout. In the vehicle control system  201 ,  202 , the gateway ECU  60  corresponds to an example of the “conversion unit” according to the present disclosure. 
     The vehicle control system  201 ,  202  to which the battery pack  10  is attached can control the input power of the battery  11  by the vehicle control method including the first to fourth steps described below. 
     In the first step (for example, S 1  in  FIG. 4 ), the vehicle control system  201 ,  202  obtains IWin and the detection value of the battery sensor  12  from the battery pack  10 . In the second step (for example, S 2  in  FIG. 5 ), the vehicle control system  201 ,  202  uses IWin and the detection value (for example, voltage, current, and temperature) of the battery sensor  12  to obtain V 1 . In the third step (for example, S 3  in  FIG. 5 ), the vehicle control system  201 ,  202  converts IWin into Win by multiplying Win by V 1 . In the fourth step (for example, S 4  in  FIG. 4 ), the vehicle control system  201 ,  202  controls the input power of the battery  11  using Win. 
     In addition, the vehicle control system  201 ,  202  to which the battery pack  10  is attached can control the output power of the battery  11  by the vehicle control method including the fifth to eighth steps described below. 
     In the fifth step, the vehicle control system  201 ,  202  obtains IWout and the detection value of the battery sensor  12  from the battery pack  10 . In the sixth step, the vehicle control system  201 ,  202  uses the detection value (for example, voltage, current, and temperature) of the battery sensor  12  and IWout to obtain V 2 . In the seventh step, the vehicle control system  201 ,  202  converts IWout into Wout by multiplying IWout by V 2 . In the eighth step, the vehicle control system  201 ,  202  controls the output power of the battery  11  using Wout. 
     According to the above vehicle control method, the vehicle control systems  201  and  202  can appropriately perform the power-based input restriction and the power-based output restriction using Win and Wout. 
     In the above-described embodiment, when the current restricting battery pack is connected to the power restricting control device, the gateway ECU  60  is adopted so that the power-based input restriction and the power-based output restriction are performed on the secondary battery included in the current restricting battery pack. That is, in the above-described embodiment, the gateway ECU  60  that is configured to be connectable to the current restricting battery pack and that cannot be connected to the power restricting battery pack is adopted. However, the present disclosure is not limited to this, and a gateway ECU  60 X shown in  FIG. 9  may be adopted instead of the gateway ECU  60  adopted in the above-described embodiment.  FIG. 9  is a diagram showing a modified example of the gateway ECU  60  shown in  FIG. 4 . 
     Referring to  FIG. 9 , the gateway ECU  60 X includes a connector C 21  for connecting a battery pack  10 A to the gateway ECU  60 X and a connector C 22  for connecting a battery pack  10 B to the gateway ECU  60 X. The battery pack  10 A is a current restricting battery pack that includes a connector C 11  for external connection and that outputs IWin, IWout, and the battery sensor signals to the connector C 11 . The battery pack  10 B is a power restricting battery pack that includes a connector C 12  for external connection and that outputs Win, Wout, and the battery sensor signals to the connector C 12 . The HV ECU  50  is connected to an output port C 3  of the gateway ECU  60 X via a signal line. 
     When the connector C 11  of the battery pack  10 A is connected to the connector C 21  of the gateway ECU  60 X, IWin, IWout, and the battery sensor signals are input from the battery pack  10 A to the connector C 21 . Then, the conversion unit  600  of the gateway ECU  60 X converts Win and IWout into Win and Wout, respectively, and Win, Wout, and the battery sensor signals are output to the output port C 3 . Then, Win, Wout, and the battery sensor signals are output from the gateway ECU  60 X to the HV ECU  50 . 
     On the other hand, when the connector C 12  of the battery pack  10 B is connected to the connector C 22  of the gateway ECU  60 X, Win, Wout, and the battery sensor signals are input from the battery pack  10 B to the connector C 22 . The gateway ECU  60 X outputs Win, Wout, and the battery sensor signals input to the connector C 22  as they are to the output port C 3 . That is, the above conversion is not performed. Thus, Win, Wout, and the battery sensor signals are output from the gateway ECU  60 X to the HV ECU  50 . 
     As described above, when IWin and IWout are input, the gateway ECU  60 X according to this modified example performs the conversion in accordance with the above expressions F1 and F2 to output Win and Wout. When Win and Wout are input, the gateway ECU  60 X outputs Win and Wout without performing the above conversion. In a vehicle including the gateway ECU  60 X, Win and Wout are output from the gateway ECU  60 X in both a case where the current restricting battery pack  10 A is used and a case where the power restricting battery pack  10 B is used. Thus, in such a vehicle, the HV ECU  50  can appropriately perform the power-based input restriction and the power-based output restriction in both a case where the current restricting battery pack  10 A is adopted and a case where the power restricting battery pack  10 B is adopted. 
     In the example shown in  FIG. 9 , the gateway ECU  60 X separately includes the input port for a current restricting battery pack (connector C 21 ) and the input port for a power restricting battery pack (connector C 22 ). However, the gateway ECU may be configured to be connectable to both the current restricting battery pack and the power restricting battery pack in another form. For example, the gateway ECU may include one input port to which both the current restricting battery pack and the power restricting battery pack can be connected. The gateway ECU may be configured to recognize whether the battery pack is the current restricting battery pack or the power restricting battery pack in the initial process when the battery pack is connected to the input port. When the battery pack connected to the input port is the current restricting battery pack, the gateway ECU may activate a conversion logic (for example, the conversion unit  600  shown in  FIG. 9 ) to convert IWin and IWout input thereto into Win and Wout, respectively, and output Win and Wout to the output port. On the other hand, when the battery pack connected to the input port is the power restricting battery pack, the gateway ECU may directly output Win and Wout input thereto, to the output port without activating the conversion logic. 
     In the above-described embodiment, the number of power upper limit values required for the input restriction of the battery  11  is one. However, the present disclosure is not limited to this, and the input restriction may be performed using a plurality of power upper limit values. For example, an HV ECU  50 X shown in  FIG. 10  may be adopted instead of the HV ECU  50  adopted in the above embodiment.  FIG. 10  is a diagram showing a modified example of the HV ECU  50  shown in  FIG. 4 . 
     Referring to  FIG. 10  together with  FIG. 4 , the hardware configuration of the HV ECU  50 X is the same as the configuration of the HV ECU  50  shown in  FIG. 2 . However, the HV ECU  50 X includes a guard unit  53  in addition to the control unit  51 . In the HV ECU  50 X, for example, the control unit  51  and the guard unit  53  are implemented by the processor  50   a  shown in  FIG. 2  and the program executed by the processor  50   a . However, the present disclosure is not limited to this, and the control unit  51  and the guard unit  53  may be implemented by dedicated hardware (electronic circuit). 
     Win, Wout, and the battery sensor signals are input to the HV ECU  50 X from the gateway ECU  60  shown in  FIG. 4 , for example. The guard unit  53  uses a map M to obtain a third power upper limit value (hereinafter, also referred to as “GWin”) indicating the upper limit value of the input power of the battery  11  and a fourth power upper limit value (hereinafter, also referred to as “GWout”) indicating the upper limit value of the output power of the battery  11 . GWin is a guard value for Win, and when Win is an abnormal value (more specifically, an excessively large value), GWin restricts the input power of the battery  11  instead of Win. GWout is a guard value for Wout, and when Wout is an abnormal value (more specifically, an excessively large value), GWout restricts the output power of the battery  11  instead of Wout. 
     The map M is information indicating the relationship between the temperature of the battery  11  and each of GWin and GWout, and is stored in the storage device  50   c  ( FIG. 2 ) in advance. A line L 11  in the map M indicates the relationship between the temperature of the battery  11  and GWin. A line L 12  in the map M indicates the relationship between the temperature of the battery  11  and GWout. 
     The guard unit  53  refers to the map M to obtain GWin and GWout in accordance with the current temperature of the battery  11 . Then, the guard unit  53  outputs the smaller one of Win and GWin to the control unit  51 , and outputs the smaller one of Wout and GWout to the control unit  51 . For example, when the temperature of the battery  11  and Win are in a state P 11  in the map M, Win is output to the control unit  51 , and when the temperature of the battery  11  and Win are in a state P 12  in the map M, GWin (line L 11 ) is output to the control unit  51 . Hereinafter, the situation where Win exceeds GWin (for example, the situation where the state P 12  is established) may be referred to as “Win with guard”. When the temperature of the battery  11  and Wout are in a state P 21  in the map M, Wout is output to the control unit  51 , and when the temperature of the battery  11  and Wout are in a state P 22  in the map M, GWout (line L 12 ) is output to the control unit  51 . Hereinafter, the situation where Wout exceeds GWout (for example, the situation where the state P 22  is established) may be referred to as “Wout with guard”. 
     The temperature of the battery  11  that is used to obtain GWin and GWout is a measured value of the temperature of the battery  11  detected by the temperature sensor  12   c  shown in  FIG. 4 , for example. For example, any one of the average cell temperature, the maximum cell temperature, and the minimum cell temperature may be adopted as the temperature of the battery  11 . 
     In addition to the power upper limit value, the battery sensor signals are also output from the guard unit  53  to the control unit  51 . The control unit  51  controls the input power and the output power of the battery  11  using the power upper limit value received from the guard unit  53 . More specifically, the control unit  51  creates the control commands S M1 , S M2  for the MG  21   a , MG  21   b  and the control command S E  for the engine  31  shown in  FIG. 1  so that the input power and the output power of the battery  11  do not exceed the power upper limit values. The control unit  51  controls the input power of the battery  11  so that the input power of the battery  11  does not exceed the smaller one of Win and GWin. As a result, the input power of the battery  11  exceeds neither Win nor GWin. The control unit  51  controls the output power of the battery  11  so that the output power of the battery  11  does not exceed the smaller one of Wout and GWout. As a result, the output power of the battery  11  exceeds neither Wout nor GWout. 
     The guard unit  53  may record Win with guard and Wout with guard in the storage device  50   c  ( FIG. 2 ) and determine, based on the recorded data, conformity/nonconformity of the battery pack mounted on the vehicle (for example, the battery pack  10  shown in  FIG. 4 ). For example, the guard unit  53  may determine that the battery pack is nonconforming when at least one of the frequency of “Win with guard” and the frequency of “Wout with guard” exceeds a predetermined value. In addition, the guard unit  53  may determine that the battery pack is nonconforming when at least one of the duration for which the state “Win with guard” continues and the duration for which the state “Wout with guard” continues exceeds a predetermined value. 
     The HV ECU  50 X may record the determination result of conformity/nonconformity of the battery pack in the storage device  50   c  ( FIG. 2 ). In addition, the HV ECU  50 X may notify a user of the nonconformity when it is determined that the battery pack is nonconforming. This notification may prompt the user to replace the battery pack. The notification process to the user is optional, and the notification may be carried out by display (for example, display of characters or images) on a display device, by sound (including voice) from a speaker, or by lighting (including blinking) of a predetermined lamp. 
     Win, Wout may exceed GWin, GWout due to insufficient accuracy of conversion of IWin, IWout into Win, Wout, respectively. Thus, when Win exceeds GWin and/or when Wout exceeds GWout, the HV ECU  50 X may transmit a predetermined signal to the battery ECU  13  shown in  FIG. 4 , so as to increase the sampling rate of the battery ECU  13  (and therefore the number of data of the battery sensor signals transmitted from the battery ECU  13  to the gateway ECU  60  per unit time). 
     According to the modified example shown in  FIG. 10 , it is possible to protect the battery  11  with GWin and GWout when Win or Wout become excessively large values for some reason. 
     In the above-described embodiment, the gateway ECU  60  includes the conversion unit  600 . However, the present disclosure is not limited to this, and another ECU may have these functions. 
       FIG. 11  is a diagram showing a first modified example of the vehicle control system shown in  FIG. 4 . Referring to  FIG. 11 , the vehicle control system according to the first modified example is the same as the vehicle control system shown in  FIG. 4  except that an HV ECU  50 Y is adopted instead of the HV ECU  50  and the gateway ECU  60  is omitted. The hardware configuration of the HV ECU  50 Y is the same as the configuration of the HV ECU  50  shown in  FIG. 2 . However, the HV ECU  50 Y includes the conversion unit  600  (see  FIG. 5 ) in addition to the control unit  51 . In the HV ECU  50 Y, for example, the control unit  51  and the conversion unit  600  are implemented by the processor  50   a  shown in  FIG. 2  and the program executed by the processor  50   a . However, the present invention is not limited to this, and the control unit  51  and the conversion unit  600  may be implemented by dedicated hardware (electronic circuit). 
     The battery pack  10  outputs IWin, IWout, and the battery sensor signals to the HV ECU  50 Y. The conversion unit  600  of the HV ECU  50 Y converts IWin and IWout input from the battery pack  10  into Win and Wout, respectively. Win and Wout are input from the conversion unit  600  to the control unit  51 . The control unit  51  creates the control commands S M1 , S M2 , and S E  for the MG  21   a , the MG  21   b , and the engine  31  shown in  FIG. 1 , respectively, and outputs the control commands S M1  and S M2  to the motor ECU  23  and outputs the control command S E  to the engine ECU  33 , so that the input power and the output power of the battery  11  do not exceed Win and Wout, respectively. 
     In the vehicle control system according to the first modified example, the HV ECU  50 Y provided separately from the battery pack  10  includes a converter (that is, the conversion unit  600 ), and the converter converts IWin and IWout into Win and Wout, respectively. Thus, the converter can be mounted on the vehicle without a change in the configuration of the battery pack  10 . Further, the HV ECU  50 Y can appropriately perform the power-based input restriction and the power-based output restriction without adding the gateway ECU  60  ( FIG. 4 ) described above. 
       FIG. 12  is a diagram showing a second modified example of the vehicle control system shown in  FIG. 4 . Referring to  FIG. 12 , the vehicle control system according to the second modified example is the same as the vehicle control system shown in  FIG. 4  except that a battery pack  10 X (including a battery ECU  13 X) is adopted instead of the battery pack  10  (including the battery ECU  13 ) and the gateway ECU  60  is omitted. The hardware configuration of the battery ECU  13 X included in the battery pack  10 X is the same as the configuration of the battery ECU  13  shown in  FIG. 2 . However, the battery ECU  13 X includes the conversion unit  600  (see  FIG. 5 ) in addition to the IWin calculation unit  131  and the IWout calculation unit  132 . In the battery ECU  13 X, for example, the IWin calculation unit  131 , the IWout calculation unit  132 , and the conversion unit  600  are implemented by the processor  13   a  shown in  FIG. 2  and the program executed by the processor  13   a . However, the present disclosure is not limited to this, and the IWin calculation unit  131 , the IWout calculation unit  132 , and the conversion unit  600  may be implemented by dedicated hardware (electronic circuit). 
     The conversion unit  600  of the battery ECU  13 X receives IWin and IWout from the IWin calculation unit  131  and the IWout calculation unit  132 , respectively, and converts IWin and IWout into Win and Wout, respectively. The battery pack  10 X outputs Win, Wout, and the battery sensor signals to the HV ECU  50 . The control unit  51  of the HV ECU  50  creates the control commands S M1 , S M2 , and S E  for the MG  21   a , the MG  21   b , and the engine  31  shown in  FIG. 1 , respectively, and outputs the control commands S M1  and S M2  to the motor ECU  23  and outputs the control command S E  to the engine ECU  33 , so that the input power and the output power of the battery  11  do not exceed Win and Wout, respectively. 
     In the vehicle control system according to the second modified example, the converter (that is, the conversion unit  600 ) is incorporated in the battery ECU  13 X (that is, inside the battery pack  10 X). With this configuration, IWin and IWout are converted into Win and Wout inside the battery pack  10 X, respectively, so Win and Wout can be output from the battery pack  10 X. Therefore, the HV ECU  50  can appropriately perform the power-based input restriction and the power-based output restriction without adding the above-described gateway ECU  60  ( FIG. 4 ). 
     In the above-described embodiment and each modified example, the output restriction of the secondary battery is performed conforming to the input restriction of the secondary battery, but the method of the output restriction of the secondary battery can be changed as appropriate. For example, the power upper limit value of the secondary battery on the output side may be calculated by a calculation method different from that for the power upper limit value of the secondary battery on the input side. 
     In the above-described embodiment and each modified example, the battery ECU  13 , the motor ECU  23 , and the engine ECU  33  are connected to the local bus B 1  (see  FIG. 2 ). However, the present disclosure is not limited to this, and the motor ECU  23  and the engine ECU  33  may be connected to the global bus B 2 . 
     The configuration of the vehicle is not limited to the configuration shown in  FIG. 1 . For example, although a hybrid vehicle is shown in  FIG. 1 , the vehicle is not limited to the hybrid vehicle and may be an electric vehicle on which an engine is not mounted. Further, the vehicle may be a plug-in hybrid vehicle (PHV) configured such that the secondary battery in the battery pack can be charged using electric power supplied from the outside of the vehicle. Further, the HV ECU  50  may be configured to directly control the SMR  14  bypassing the battery ECU  13 . The battery  11  (secondary battery) included in the battery pack  10  is not limited to the assembled battery and may be a single battery. 
     The modified examples described above may be implemented in any combination. The embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present invention is shown by the claims, rather than the above embodiment, and is intended to include all modifications within the meaning and the scope equivalent to those of the claims.