JP2013099124A - Battery system and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply electric power from a first battery (a high pressure battery) to a second battery (an auxiliary machine battery), thereby preventing the deterioration in the state of charge (SOC) of the first battery.SOLUTION: A first battery receives electric power supply from an external power source and supplies the electric power to a motor which allows a vehicle to drive. A second battery supplies electric power to an auxiliary machine mounted on the vehicle. A converter converts output voltages of the external power source and the first battery into a voltage that is accepted by the second battery and outputs the converted electric power to the second battery. A controller controls the driving of the converter. The controller lowers the output voltage of the converter, thereby preventing electric power from being supplied from the first battery to the second battery, when the electric power from the external power source is supplied to the first battery and the second battery.

Description

  The present invention relates to a battery system including two batteries that are charged with each other, and a method for controlling the battery system.

  The vehicle is equipped with a high voltage battery that outputs energy used for traveling of the vehicle and an auxiliary battery that outputs driving power of the auxiliary machine. By supplying electric power from the external power source to the high voltage battery and the auxiliary battery, the high voltage battery and the auxiliary battery can be charged.

  A charger can be used for charging the high-voltage battery and the auxiliary battery. In the configuration in which the high voltage battery and the auxiliary battery are connected in parallel to the charger, the output power of the charger can be supplied to the high voltage battery and the auxiliary battery.

JP 2006-197691 A JP 2009-027812 A JP 2009-201282 A

  In a configuration in which a high voltage battery and an auxiliary battery are connected in parallel to the charger, when the SOC of the auxiliary battery is low, the power required by the auxiliary battery is higher than the output power of the charger. May be high. In this case, the power shortage of the auxiliary battery can be compensated by supplying the power of the high voltage battery to the auxiliary battery.

  However, when the SOC of the high voltage battery is lowered, if the electric power of the high voltage battery is supplied to the auxiliary battery, the high voltage battery may be excessively discharged.

  The battery system according to the first aspect of the present invention receives a power supply from an external power source, and supplies a first battery that supplies power to a motor that runs the vehicle, and a second battery that supplies power to an auxiliary device mounted on the vehicle. A battery, and an external power source and a converter that converts the output voltage of the first battery into a voltage corresponding to the second battery and outputs the converted electric power to the second battery. The controller controls the drive of the converter. When the controller supplies power from the external power source to the first battery and the second battery, the controller does not supply power from the first battery to the second battery by reducing the output voltage of the converter.

  According to the first invention of the present application, by reducing the output voltage of the converter, it is possible to prevent power from being supplied from the first battery to the second battery, and the SOC of the first battery is reduced. Can be suppressed. In particular, overdischarge of the first battery can be suppressed by not discharging the first battery in a state where the SOC of the first battery is lowered.

  When it is detected that electric power is supplied from the first battery to the second battery, the output voltage of the converter can be reduced. As a result, when the first battery and the second battery are charged using the power of the external power supply, it is possible to perform a process of not discharging the first battery after confirming the discharge of the first battery.

  On the other hand, before detecting that power is supplied from the first battery to the second battery, the output voltage of the converter can be lowered. Thereby, when the first battery and the second battery are charged using the power of the external power source, the discharge of the first battery can be avoided.

  A charger that supplies power from an external power source to the first battery and the second battery can be provided. When the charger output power can be changed, the charger output power can be increased before the converter output voltage is reduced. By increasing the output power of the charger, the charging power of the first battery and the second battery can be increased, and the discharge of the first battery can be suppressed.

  In the state where power is not supplied from the first battery to the second battery, the power supplied from the converter to the second battery is supplied from the second battery to the auxiliary device by increasing the output voltage of the converter. It can be higher than the power. Thereby, discharge of a 2nd battery can be suppressed and charge of a 2nd battery can be ensured.

  Here, when it is detected that the electric power supplied from the converter to the second battery is lower than the electric power supplied from the second battery to the auxiliary machine, the output voltage of the converter can be increased. Thereby, after confirming the discharge of the second battery, it is possible to perform a process that does not discharge the second battery. On the other hand, the output voltage of the converter can be raised before detecting that the power supplied from the converter to the second battery is lower than the power supplied from the second battery to the auxiliary machine. Thereby, the discharge of the second battery can be avoided.

  When the output power of the charger can be changed, the output power of the charger can be increased before increasing the output voltage of the converter. Thereby, the charge power of the second battery can be increased, and the discharge of the second battery can be suppressed.

  Completing charging of the first battery and the second battery based on the first electric energy required for completing the charging of the first battery and the second electric energy required for completing the charging of the second battery You can arrange the time to let.

  Specifically, the output voltage of the converter can be increased when the charge power of the second battery is lower than the charge power of the first battery with reference to the ratio of the first power amount and the second power amount. When the charging power of the second battery is lower than the charging power of the first battery, the charging of the first battery has priority over the charging of the second battery. Therefore, by raising the output voltage of the converter, the charging of the second battery can be prioritized over the charging of the first battery, and the time for completing the charging of the first battery and the second battery can be made uniform. .

  When the charge power of the second battery is higher than the charge power of the first battery with reference to the ratio of the first power amount and the second power amount, the output voltage of the converter can be lowered. When the charging power of the second battery is higher than the charging power of the first battery, the charging of the second battery has priority over the charging of the first battery. Therefore, by lowering the output voltage of the converter, the charging of the first battery can be prioritized over the charging of the second battery, and the time for completing the charging of the first battery and the second battery can be made uniform. .

  The second invention of the present application is a control method for controlling the charging of the battery system described in the first invention of the present application. When power from an external power source is supplied to the first battery and the second battery, the output voltage of the converter is set. By reducing the power, the power supply from the first battery to the second battery is not performed. Also in the second invention of the present application, the same effect as that of the first invention of the present application can be obtained.

It is a figure which shows the structure of the battery system which is Example 1. FIG. In Example 1, it is a figure which shows the structure of a part of battery system. 3 is a flowchart showing a part of processing of the battery system which is Embodiment 1. 3 is a flowchart showing a part of processing of the battery system which is Embodiment 1. FIG. 3 is a diagram illustrating a partial configuration of a battery system that is Embodiment 2. 6 is a flowchart showing a part of processing of the battery system which is Embodiment 3.

  Examples of the present invention will be described below.

  A battery system (battery system) that is Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a battery system. The battery system of the present embodiment is mounted on a vehicle. Vehicles include hybrid cars and electric cars. The hybrid vehicle includes an engine or a fuel cell as a power source for running the vehicle, in addition to a high voltage battery described later. An electric vehicle includes only a high voltage battery as a power source for running the vehicle.

  The high-voltage battery (first battery) 10 includes a plurality of single cells 11 connected in series. As the cell 11, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor (capacitor) can be used instead of the secondary battery. The number of the single cells 11 can be appropriately set based on the required output of the high voltage battery 10 and the like. In the present embodiment, the plurality of unit cells 11 are connected in series, but the plurality of unit cells 11 connected in parallel may be included in the high-voltage battery 10.

  The voltage sensor 21 detects the voltage between the terminals of the high voltage battery 10 and outputs the detection result to the controller 26. The voltage sensor 21 can be used to detect the voltage between terminals of each unit cell 11 or to detect the voltage between terminals of a battery block including at least two unit cells 11. The current sensor 22 detects a current flowing through the high voltage battery 10 and outputs a detection result to the controller 26.

  The controller 26 has a built-in memory 26a. The memory 26a stores various information for the controller 26 to perform predetermined processing. In the present embodiment, the memory 26 a is built in the controller 26, but the memory 26 a may be provided outside the controller 26.

  A system main relay SMR-B is provided on the positive electrode line PL of the high-voltage battery 10. System main relay SMR-B is switched between on and off by receiving a control signal from controller 26. A system main relay SMR-G is provided on the negative electrode line NL of the high-voltage battery 10. System main relay SMR-G is switched between on and off by receiving a control signal from controller 26.

  The charger 23 is connected to the positive electrode line PL and the negative electrode line NL. The charger 23 supplies power from the external power source to the high voltage battery 10. The external power source is a power source arranged outside the vehicle, and examples of the external power source include a commercial power source. When the external power supply supplies AC power, the charger 23 converts AC power into DC power and supplies the DC power to the high voltage battery 10. When the external power supply supplies DC power, the DC power can be supplied to the high voltage battery 10. In response to the control signal from the controller 26, the charger 23 can change the power output from the charger 23.

  A system main relay SMR-P and a current limiting resistor R are connected in parallel to the system main relay SMR-G. System main relay SMR-P is switched between on and off by receiving a control signal from controller 26. The current limiting resistor R is used to suppress the inrush current from flowing when the high voltage battery 10 is connected to a load (such as the charger 23 or the inverter 24).

  When the high voltage battery 10 is connected to the load, the controller 26 switches the system main relay SMR-B from off to on and switches the system main relay SMR-P from off to on. As a result, a current flows through the current limiting resistor R. Next, the controller 26 switches the system main relay SMR-P from on to off after switching the system main relay SMR-G from off to on.

  Thereby, the connection between the high voltage battery 10 and the load is completed. On the other hand, when disconnecting the connection between the high voltage battery 10 and the load, the controller 26 switches the system main relays SMR-B and SMR-G from on to off. When power is supplied from the charger 23 to the high voltage battery 10, the system main relays SMR-B and SMR-G are on.

  The inverter 24 converts the DC power from the high-voltage battery 10 into AC power and outputs the AC power to the motor / generator 25. For example, a three-phase AC motor can be used as the motor / generator 25. The motor / generator 25 receives AC power from the inverter 24 and generates kinetic energy for running the vehicle. The kinetic energy generated by the motor generator 25 is transmitted to the wheels.

  When the vehicle is decelerated or stopped, the motor / generator 25 converts kinetic energy generated during braking of the vehicle into electric energy (AC power). The inverter 24 converts the AC power generated by the motor / generator 25 into DC power and outputs the DC power to the high-voltage battery 10. Thereby, the high voltage battery 10 can store regenerative electric power.

  In this embodiment, the high voltage battery 10 is connected to the inverter 24, but the present invention is not limited to this. Specifically, a booster circuit can be arranged in a current path connecting the high voltage battery 10 and the inverter 24. By using the booster circuit, the output voltage of the high voltage battery 10 can be boosted. Further, the booster circuit can step down the voltage output from the inverter 24 to the high voltage battery 10.

  FIG. 2 is a diagram showing a configuration for driving an auxiliary machine mounted on the vehicle.

  The DC / DC converter 31 steps down the output voltage of the high voltage battery 10 and outputs the reduced power to the auxiliary battery (second battery) 32 and the auxiliary device 33. The DC / DC converter 31 operates in response to a control signal from the controller 26. By supplying the output power of the DC / DC converter 31 to the auxiliary battery 32, the auxiliary battery 32 can be charged. On the other hand, in the hybrid vehicle, the auxiliary battery 32 can be charged by supplying the auxiliary battery 32 with electric power from an alternator that generates electric power by receiving the driving force of the engine.

  The rated voltage of high voltage battery 10 is higher than the rated voltage of auxiliary battery 32. The power of the auxiliary battery 32 is supplied to the auxiliary machine 33. Examples of the auxiliary machine 33 include a controller 26, a circuit for driving the system main relays SMR-B, SMR-G, and SMR-P, air conditioning equipment, lamps, sound equipment, and a display.

  Current sensor 34 detects the current flowing through auxiliary battery 32 and outputs the detection result to controller 26. Voltage sensor 35 detects the voltage of auxiliary battery 32 and outputs the detection result to controller 26.

  Some processes in the battery system of the present embodiment will be described with reference to the flowcharts shown in FIGS. 3 and 4. The processing shown in FIGS. 3 and 4 is processing when the high-voltage battery 10 and the auxiliary battery 32 are charged using the charger 23, and is executed by the controller 26. The processes shown in FIGS. 3 and 4 are performed at a predetermined cycle.

  In step S <b> 101 of FIG. 3, the controller 26 acquires the voltage value of the high voltage battery 10 based on the output of the voltage sensor 21. Further, the controller 26 acquires the value of the current flowing through the high voltage battery 10 based on the output of the current sensor 22. By acquiring the voltage value and current value of the high voltage battery 10, the controller 26 calculates the electric power W <b> 1 in input to the high voltage battery 10.

  When the high voltage battery 10 is charged, the input power W1in shows a positive value, and when the high voltage battery 10 is discharged, the input power W1in shows a negative value. The input power W1in is obtained by subtracting the power input to the DC / DC converter 31 from the output power Wchg of the charger 23.

  In step S102, the controller 26 determines whether or not the input power W1in is higher than 0 [kW]. When the input power W1in is higher than 0 [kW], the process proceeds to step S107, and when the input power W1in is lower than 0 [kW], the process proceeds to step S103.

  In step S <b> 103, the controller 26 increases the output power Wchg of the charger 23 by outputting a control signal to the charger 23. When the output power Wchg of the charger 23 is the maximum power that can be set, the controller 26 maintains the output power Wchg of the charger 23 at the maximum power.

  In step S104, the controller 26 waits for a predetermined time after outputting a control signal for increasing the output power Wchg to the charger 23. The predetermined time is a time until the output power of the charger 23 is stabilized, and can be determined in advance. Information about the predetermined time can be stored in the memory 26a. The controller 26 can measure a predetermined time by using a timer.

  In step S105, the controller 26 calculates the input power W1in of the high-voltage battery 10 again based on the detection results of the voltage sensor 21 and the current sensor 22. Then, the controller 26 determines whether or not the calculated input power W1in is higher than 0 [kW]. When the input power W1in is higher than 0 [kW], the process proceeds to step S107, and when the input power W1in is lower than 0 [kW], the process proceeds to step S106.

  In step S <b> 106, the controller 26 changes the output voltage V (n) of the DC / DC converter 31. Specifically, the controller 26 subtracts a predetermined value ΔV from the output voltage V (n−1) of the DC / DC converter 31 set up to this time, so that the current output of the DC / DC converter 31 is obtained. The voltage V (n) is set. If the predetermined value ΔV is too large, the output voltage of the DC / DC converter 31 will be hunted with respect to the set voltage V (n). In consideration of this point, the predetermined value ΔV may be set.

  In step S107, the controller 26 sets the current output voltage V (n) of the DC / DC converter 31 to the same value as the previous output voltage V (n-1). That is, the controller 26 maintains the output voltage of the DC / DC converter 31. In step S108, the controller 26 waits for a predetermined time after outputting a control signal for setting the output voltage V (n) to the DC / DC converter 31. The predetermined time is a time until the output voltage of the DC / DC converter 31 is stabilized, and can be determined in advance. Information about the predetermined time can be stored in the memory 26a. The controller 26 can measure a predetermined time by using a timer.

  In step S <b> 201 of FIG. 4, the controller 26 acquires the voltage value of the auxiliary battery 32 based on the output of the voltage sensor 35. Further, the controller 26 acquires the value of the current flowing through the auxiliary battery 32 based on the output of the current sensor 34. By acquiring the voltage value and the current value of the auxiliary battery 32, the controller 26 calculates the electric power W2in input to the auxiliary battery 32.

  When the auxiliary battery 32 is charged, the input power W2in indicates a positive value, and when the auxiliary battery 32 is discharged, the input power W2in indicates a negative value. The input power W2in is obtained by subtracting the power supplied from the auxiliary battery 32 to the auxiliary machine 33 from the output power of the DC / DC converter 31.

  In step S202, the controller 26 determines whether or not the input power W2in is higher than 0 [kW]. When the input power W2in is higher than 0 [kW], the process proceeds to step S207, and when the input power W2in is lower than 0 [kW], the process proceeds to step S203. When the input power W2in is lower than 0 [kW], power is supplied from the auxiliary battery 32 to the auxiliary machine 33.

  In step S203, the controller 26 outputs a control signal to the charger 23, thereby increasing the output power Wchg of the charger 23 to a maximum power that can be set. When the output power Wchg of the charger 23 is the maximum power, the controller 26 maintains the output power Wchg of the charger 23 at the maximum power.

  In step S204, the controller 26 waits for a predetermined time after outputting a control signal for increasing the output power Wchg to the charger 23. The process in step S204 is the same as the process in step S104 in FIG.

  In step S205, the controller 26 calculates the input power W2in of the auxiliary battery 32 again based on the detection results of the current sensor 34 and the voltage sensor 35. Then, the controller 26 determines whether or not the calculated input power W2in is higher than 0 [kW]. When the input power W2in is higher than 0 [kW], the process proceeds to step S207. When the input power W2in is lower than 0 [kW], the process proceeds to step S206.

  In step S206, the controller 26 changes the output voltage V (n) of the DC / DC converter 31. Specifically, the controller 26 adds the predetermined value ΔV from the previously set output voltage V (n−1) of the DC / DC converter 31 to thereby output the current output voltage of the DC / DC converter 31. Set V (n).

  If the predetermined value ΔV is too large, the output voltage of the DC / DC converter 31 will be hunted with respect to the set voltage V (n). In consideration of this point, the predetermined value ΔV may be set. The predetermined value ΔV used in the process of step S106 in FIG. 3 and the predetermined value ΔV used in the process of step S206 in FIG. 4 may be equal to each other or different from each other.

  In step S207, the controller 26 sets the current output voltage V (n) of the DC / DC converter 31 to the same value as the previous output voltage V (n-1). That is, the controller 26 maintains the output voltage of the DC / DC converter 31. In step S208, the controller 26 waits for a predetermined time after outputting the control signal for setting the output voltage V (n) to the DC / DC converter 31. The process in step S208 is the same as the process in step S108 in FIG.

  3 and 4, when charging the high voltage battery 10 and the auxiliary battery 32 using the charger 23, the input power W1in of the high voltage battery 10 and the input power W2in of the auxiliary battery 32 are 0 [ It is possible to prevent power from being supplied from the high-voltage battery 10 to the auxiliary battery 32 by confirming that it is higher than [kW].

  Further, when the input power W1in of the high voltage battery 10 is lower than 0 [kW], in other words, when the high voltage battery 10 is discharged, the output voltage V (n) of the DC / DC converter 31 is decreased, The electric power supplied from the charger 23 to the high voltage battery 10 can be increased. Thereby, the high voltage battery 10 can be actively charged, and the input power W1in of the high voltage battery 10 can be made higher than 0 [kW].

  When the input power W2in of the auxiliary battery 32 is lower than 0 [kW], in other words, when the auxiliary battery 32 is discharged, by increasing the output voltage V (n) of the DC / DC converter 31, The electric power supplied from the DC / DC converter 31 to the auxiliary battery 32 can be increased. Thereby, the auxiliary battery 32 can be positively charged, and the input power W2in of the auxiliary battery 32 can be made higher than 0 [kW]. By preventing discharge of the auxiliary battery 32, it is possible to prevent power from being supplied from the high voltage battery 10 to the auxiliary battery 32, and it is also possible to prevent discharge of the high voltage battery 10.

  When the SOC (State of Charge) of the auxiliary battery 32 decreases, the electric power for charging the auxiliary battery 32 may be higher than the output electric power of the charger 23. In other words, the charging power required by the auxiliary battery 32 is insufficient. In this case, by supplying the power of the high voltage battery 10 to the auxiliary battery 32, the power shortage in the auxiliary battery 32 can be compensated. When the power consumption for driving the auxiliary machine 33 is increased or the auxiliary machine 33 is left in a state of being driven, the SOC of the auxiliary battery 32 is likely to be lowered. The SOC indicates the ratio of the current charge capacity to the full charge capacity.

  Here, if the SOC of the high voltage battery 10 is sufficiently high, the high voltage battery 10 may be discharged. On the other hand, if the high voltage battery 10 is discharged while the SOC of the high voltage battery 10 is lowered, the SOC of the high voltage battery 10 is further lowered. Depending on the vehicle, the SOC of the high-voltage battery 10 may be lowered. For example, in an electric vehicle, the high voltage battery 10 may be discharged until the SOC of the high voltage battery 10 reaches around 0%. In this case, if the high voltage battery 10 is discharged to charge the auxiliary battery 32, the high voltage battery 10 may be overdischarged.

  According to the present embodiment, by changing the output voltage V (n) of the DC / DC converter 31, the high-voltage battery 10 and the auxiliary battery 32 are discharged when charging is performed using the charger 23. Can be prevented.

  When the SOC of the high-voltage battery 10 is lower than a predetermined threshold, the processing shown in FIGS. 3 and 4 can be performed, or the processing shown in FIGS. 3 and 4 is performed regardless of the SOC of the high-voltage battery 10. It can also be done.

  In this embodiment, when the input power W1in or the input power W2in is lower than 0 [kW], the output voltage V (n) of the DC / DC converter 31 is changed. However, the present invention is not limited to this. That is, the output voltage V (n) of the DC / DC converter 31 can be changed before the input power W1in or the input power W2in becomes lower than 0 [kW].

  Specifically, power greater than 0 [kW] is determined as a threshold, and the output voltage V (n) of the DC / DC converter 31 is changed when the input power W1in or the input power W2in is lower than the threshold. be able to. By setting the threshold value higher than 0 [kW], it is possible to avoid the input power W1in and W2in from becoming lower than 0 [kW], and to avoid discharge of the high voltage battery 10 and the auxiliary battery 32. .

  A battery system that is Embodiment 2 of the present invention will be described. About the same member as the member demonstrated in Example 1, the same code | symbol is used and detailed description is abbreviate | omitted. Hereinafter, differences from the first embodiment will be mainly described.

  FIG. 5 is a diagram showing a part of the configuration of the battery system of the present embodiment, and corresponds to FIG. In the first embodiment (FIG. 2), the input power W2in of the auxiliary battery 32 is calculated using the current sensor 34 and the voltage sensor 35. On the other hand, in this embodiment, the output power Wchg of the charger 23 is calculated.

  The current sensor 36 detects the current value flowing from the charger 23 and outputs the detection result to the controller 26. The voltage sensor 37 detects the output voltage of the charger 23 and outputs the detection result to the controller 26. The controller 26 can calculate the output power Wchg of the charger 23 based on the detection results of the current sensor 36 and the voltage sensor 37.

  If the conversion efficiency ξ of the DC / DC converter 31 is specified in advance, the input power W2in of the auxiliary battery 32 can be expressed by the following equation (1). The conversion efficiency ξ is a positive number smaller than 1.

  W2in = (Wchg−W1in) × ξ (1)

  In Expression (1), power is not supplied from the auxiliary battery 32 to the auxiliary machine 33. When power is being supplied from the auxiliary battery 32 to the auxiliary machine 33, the input power W2in of the auxiliary battery 32 can be expressed by the following equation (2).

  W2in = (Wchg−W1in) × ξ−Waux (2)

  In Expression (2), Waux is the power consumption of the auxiliary machine 33. The power consumption of the auxiliary machine 33 can be measured using a current sensor and a voltage sensor. On the other hand, the power consumption of the auxiliary machine 33 can be regarded as a constant value. When charging using the charger 23, only a specific auxiliary machine 33 is often operating. For this reason, if the power consumption of the specific auxiliary machine 33 is measured in advance, the power Waux can be handled as a fixed value. The power consumption of the specific auxiliary machine 33 includes, for example, power for operating the controller 26 and power for driving the system main relays SMR-B, SMR-G, and SMR-P.

  Also in the present embodiment, the same processing as in the first embodiment (FIGS. 3 and 4) can be performed. As described in the first embodiment (FIG. 3), when the input power W1in of the high voltage battery 10 is higher than 0 [kW], the output voltage V (n) of the DC / DC converter 31 is maintained without being changed. Can do. On the other hand, when the input power W1in of the high voltage battery 10 is lower than 0 [kW], the output voltage V (n) of the DC / DC converter 31 can be lowered. Thereby, the high voltage battery 10 can be actively charged, and the discharge of the high voltage battery 10 can be prevented.

  When the input power W2in of the auxiliary battery 32 is higher than 0 [kW], the output voltage V (n) of the DC / DC converter 31 can be maintained without being changed. On the other hand, when the input power W2in of the auxiliary battery 32 is lower than 0 [kW], the output voltage V (n) of the DC / DC converter 31 can be increased. The input power W2in can be calculated based on the above formula (1) or formula (2).

  Increasing the output voltage V (n) of the DC / DC converter 31 can positively charge the auxiliary battery 32 and prevent the auxiliary battery 32 from being discharged. By preventing the auxiliary battery 32 from being discharged, it is possible to prevent power from being supplied from the high voltage battery 10 to the auxiliary battery 32 and to prevent the high voltage battery 10 from being discharged.

  A battery system that is Embodiment 3 of the present invention will be described. In this example, the configuration of the battery system is the same as that of Example 1 or Example 2. About the same member as the member demonstrated in Example 1, 2, the same code | symbol is used and detailed description is abbreviate | omitted. Hereinafter, differences from the first and second embodiments will be mainly described.

  In the present embodiment, charging of the high voltage battery 10 and the auxiliary battery 32 is completed simultaneously. This control will be described with reference to the flowchart shown in FIG. The process shown in FIG. 6 is executed by the controller 26.

  In step S301, the controller 26 calculates the input power W1in of the high voltage battery 10 and the input power W2in of the auxiliary battery 32. The method for calculating the input power W1in and W2in is the same as the method described in the first and second embodiments.

  In step S <b> 302, the controller 26 calculates an electric energy E <b> 1 necessary for completing the charging of the high-voltage battery 10 and an electric energy E <b> 2 necessary for completing the charging of the auxiliary battery 32. The electric energy E1 can be calculated based on the SOC of the high voltage battery 10 and the full charge capacity of the high voltage battery 10.

  If the correspondence relationship between the SOC and OCV (Open Circuit Voltage) is obtained in the high voltage battery 10, the SOC can be specified from the OCV of the high voltage battery 10. The full charge capacity of the high voltage battery 10 can be obtained in advance, or can be calculated based on the integrated current value and the amount of change in the SOC when the high voltage battery 10 is charged or discharged.

  The electric energy E2 can be calculated based on the SOC of the auxiliary battery 32 and the full charge capacity of the auxiliary battery 32. If the correspondence relationship between the SOC and the OCV is obtained in the auxiliary battery 32, the SOC can be specified from the OCV of the auxiliary battery 32. The full charge capacity of the auxiliary battery 32 can be obtained in advance, or can be calculated based on the integrated current value and the amount of change in the SOC when the auxiliary battery 32 is charged or discharged.

  In step S303, the controller 26 determines whether or not the input power W2in satisfies the condition of the following expression (3).

  In Expression (3), α is a positive constant that sets the hysteresis. Α can also be set to 0.

  In order to complete the charging of the high voltage battery 10 and the auxiliary battery 32 at the same time, the condition of the following formula (4) may be satisfied.

  E1 / W1in = E2 / W2in (4)

  Formula (4) is represented by Formula (5).

  In the equation (5), when the hysteresis is taken into consideration, the right side of the equation (3) is obtained. When the input power W2in satisfies the condition of the expression (3), the charging of the high voltage battery 10 is prioritized over the charging of the auxiliary battery 32. When the input power W2in satisfies the condition of Expression (3), the process proceeds to step S304. When the input power W2in does not satisfy the condition of Expression (3), the process proceeds to step S305.

  In step S304, the controller 26 increases the output voltage V (n) of the DC / DC converter 31. The process for increasing the output voltage V (n) is the same as the process in the first embodiment (step S206 in FIG. 4). By increasing the output voltage V (n) of the DC / DC converter 31, the charging of the auxiliary battery 32 can be prioritized over the charging of the high voltage battery 10. As a result, the auxiliary battery 32 and the high voltage battery 10 can be prioritized. Can be completed at the same time.

  In step S305, the controller 26 determines whether or not the input power W2in satisfies the condition of the following equation (6). In Expression (6), α is a positive constant that sets hysteresis. Α can also be set to 0.

  In equation (5), when the hysteresis is taken into consideration, the right side of equation (6) is obtained. When the input power W2in satisfies the condition of the equation (6), the charging of the auxiliary battery 32 is prioritized over the charging of the high voltage battery 10. When the input power W2in satisfies the condition of Expression (6), the process proceeds to Step S306. When the input power w2in does not satisfy the condition of Expression (6), the process proceeds to Step S307.

  In step S <b> 306, the controller 26 decreases the output voltage V (n) of the DC / DC converter 31. The process for reducing the output voltage V (n) is the same as the process in the first embodiment (step S106 in FIG. 3). By reducing the output voltage V (n) of the DC / DC converter 31, the charging of the high voltage battery 10 can be prioritized over the charging of the auxiliary battery 32. As a result, the high voltage battery 10 and the auxiliary battery 32 are given priority. Can be completed at the same time.

  In step S307, the controller 26 maintains the output voltage V (n) of the DC / DC converter 31 without changing it.

10: High-voltage battery (first battery) 11: Cell 21: Voltage sensor 22: Current sensor 23: Charger 24: Inverter 25: Motor generator 26: Controller 26a: Memory 31: DC / DC converter 32: Auxiliary battery (Second battery) 33: Auxiliary machine 34: Current sensor 35: Voltage sensor

Claims (14)

A first battery that receives power from an external power source and supplies power to a motor that drives the vehicle;
A second battery for supplying power to an auxiliary device mounted on the vehicle;
A converter that converts the output voltage of the external power source and the first battery into a voltage corresponding to the second battery, and outputs the converted electric power to the second battery;
A controller for controlling the drive of the converter,
When the controller supplies power from the external power source to the first battery and the second battery, the controller supplies power from the first battery to the second battery by reducing the output voltage of the converter. A battery system characterized by not being performed.   2. The battery system according to claim 1, wherein when the controller detects that power is supplied from the first battery to the second battery, the controller reduces the output voltage of the converter.   2. The battery system according to claim 1, wherein the controller reduces an output voltage of the converter before detecting that electric power is supplied from the first battery to the second battery. A charger for supplying power from the external power source to the first battery and the second battery;
4. The battery system according to claim 1, wherein the controller increases the output power of the charger before decreasing the output voltage of the converter. 5.   The controller increases the power supplied from the converter to the second battery by increasing the output voltage of the converter in a state where power is not supplied from the first battery to the second battery. 5. The battery system according to claim 1, wherein the power is higher than power supplied from the second battery to the auxiliary device. 6.   The controller increases the output voltage of the converter when detecting that the power supplied from the converter to the second battery is lower than the power supplied from the second battery to the auxiliary machine. The battery system according to claim 5.   The controller increases the output voltage of the converter before detecting that the power supplied from the converter to the second battery is lower than the power supplied from the second battery to the auxiliary machine. The battery system according to claim 5. A charger for supplying power from the external power source to the first battery and the second battery;
8. The battery system according to claim 5, wherein the controller increases the output power of the charger before increasing the output voltage of the converter. 9. The controller is
Calculating a first electric energy required to complete charging of the first battery and a second electric energy required to complete charging of the two batteries;
When the charging power of the second battery is lower than the charging power of the first battery, based on the ratio of the first power amount and the second power amount, the output voltage of the converter is increased,
When the charge power of the second battery is higher than the charge power of the first battery, based on the ratio of the first power amount and the second power amount, the output voltage of the converter is reduced.
The battery system according to any one of claims 1 to 8, wherein: A control method for controlling charging of a battery system,
The battery system is
A first battery that receives power from an external power source and supplies power to a motor that drives the vehicle;
A second battery for supplying power to an auxiliary device mounted on the vehicle;
A converter that converts the output voltage of the external power source and the first battery into a voltage corresponding to the second battery, and outputs the converted power to the second battery;
When power from the external power source is supplied to the first battery and the second battery, power supply from the first battery to the second battery is not performed by reducing the output voltage of the converter. A control method characterized by the above. The battery system includes a charger that supplies power from the external power source to the first battery and the second battery;
The control method according to claim 10, wherein the output power of the charger is increased before the output voltage of the converter is decreased.   The power supplied from the converter to the second battery is increased by increasing the output voltage of the converter in a state where power is not supplied from the first battery to the second battery. The control method according to claim 10 or 11, wherein the power is higher than the power supplied to the auxiliary machine. The battery system includes a charger that supplies power from the external power source to the first battery and the second battery;
The control method according to claim 12, wherein the output power of the charger is increased before the output voltage of the converter is increased. Calculating a first electric energy required to complete charging of the first battery and a second electric energy required to complete charging of the two batteries;
When the charging power of the second battery is lower than the charging power of the first battery, based on the ratio of the first power amount and the second power amount, the output voltage of the converter is increased,
When the charge power of the second battery is higher than the charge power of the first battery, based on the ratio of the first power amount and the second power amount, the output voltage of the converter is reduced.
The control method according to claim 10, wherein: