JP2009273326A - Control device for accumulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device capable of improving the startability of a vehicle system in the control device for controlling the charge/discharge of an accumulator. <P>SOLUTION: The control device includes: controllers (1, 6) that change a control central value (SOC) for controlling a charge state of the accumulator (20); and an information obtaining part (18) that obtains information in order to predict the temperature of the accumulator when the vehicle system (9) is restarted. The controllers set the control central value so that output of the accumulator in the predicted temperature from the information obtained by the information obtaining part becomes equal to or higher than the starting electric power required for restarting the system. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device that controls charging / discharging of a power storage device.

  Conventionally, there is a vehicle on which an assembled battery composed of a plurality of single cells (secondary batteries) is mounted. In this vehicle, the output of the assembled battery is used to drive the vehicle, or kinetic energy generated when the vehicle is braked is converted into electric energy to charge the assembled battery.

Here, the charge / discharge control of the secondary battery is generally performed based on the SOC (charged state) value indicating the remaining capacity of the secondary battery. In charge / discharge control, a reference value (also referred to as a control center value) that is the center of the SOC control range is set.
JP 2007-31309 A JP 2004-25979 A

  The lower the SOC of the secondary battery, the greater the maximum charge power for the secondary battery. Therefore, if the control center value of the SOC is lowered, the kinetic energy of the vehicle can be charged as regenerative power, and the fuel consumption of the vehicle Can be improved.

  Here, since the secondary battery stores electric energy by a chemical reaction, the charge / discharge characteristics change depending on the temperature condition. That is, when the control center value of the SOC is lowered, the power that can be output from the secondary battery is also lowered.

  On the other hand, in order to start the vehicle system using the output of the secondary battery, electric power of a predetermined value or more is required. However, if the SOC control center value is too low, the output of the secondary battery may become lower than the power required to start the vehicle system depending on the temperature conditions. In this case, the vehicle system cannot be started.

  Therefore, an object of the present invention is to provide a control device that can improve startability of a vehicle system in a control device that controls charging and discharging of a power storage device.

  The present invention is a control device that is mounted on a vehicle and controls charging / discharging of a power storage device, and a controller that changes a control center value used to control a charge state of the power storage device, and a vehicle system is restarted And an information acquisition unit that acquires information for predicting the temperature of the power storage device. Then, the controller sets the control center value so that the output of the power storage device at the predicted temperature predicted from the acquisition information of the information acquisition unit is equal to or higher than the starting power for restarting the system.

  Here, at the predicted temperature, when the output of the power storage device obtained by the discharge control at the currently set control center value is lower than the starting power, the control center value is changed in the direction in which the output of the power storage device increases. Can be made. Specifically, the SOC as the control center value can be made higher than the current set value. Thereby, the discharge power of the power storage device can be made higher than the starting power, and the vehicle system can be easily started. Note that when the control center value is changed in a direction in which the output of the power storage device increases, charging of the power storage device is permitted.

  On the other hand, the control center value is changed in the direction in which the chargeable amount of the power storage device increases within a range where the output of the power storage device at the predicted temperature obtained by the discharge control at the control center value is equal to or higher than the starting power. be able to. Specifically, the SOC as the control center value can be lowered in a state where the discharge power of the power storage device at the predicted temperature is higher than the starting power. Thereby, more electric power can be charged with respect to an electrical storage apparatus, and the fuel consumption of a vehicle can be improved. Note that, when the control center value is changed in a direction in which the chargeable amount of the power storage device increases, discharging of the power storage device is permitted.

  The power storage device can be composed of a lithium ion battery. And the control apparatus of this invention can be mounted in a vehicle.

  According to the present invention, the vehicle system is restarted by setting the control center value so that the output of the power storage device at the predicted temperature is equal to or higher than the starting power for restarting the vehicle system. Sometimes the system can be easily started.

  Examples of the present invention will be described below.

  A vehicle that is Embodiment 1 of the present invention will be described with reference to FIG. Here, FIG. 1 is a block diagram showing a partial configuration of the vehicle of the present embodiment.

  The vehicle of the present embodiment includes an assembled battery 20, system relays SR1 and SR2, a PCU (Power Control Unit) 8, a motor generator (MG) 10, an engine 9, and a power split mechanism 11. is doing. That is, the vehicle of the present embodiment is a hybrid vehicle provided with the assembled battery 20 and the engine 9 as a power source used for running the vehicle. In addition, it can replace with the engine 9 and can use a fuel cell, and can also use only the assembled battery 20 as a motive power source.

  The assembled battery 20 is prepared by preparing a plurality of battery modules in which a plurality of single cells 21 are electrically connected in series, and these battery modules are electrically connected in series. As the cell 21, for example, a secondary battery such as a lithium ion battery or a nickel metal hydride battery can be used. An electric double layer capacitor may be used instead of the secondary battery.

  The positive electrode and the negative electrode of the assembled battery 20 are connected to the PCU 8 via the system relays SR1 and SR2, respectively, and the PCU 8 controls the charge amount and the discharge amount of the assembled battery 20.

  The inverter included in the PCU 8 converts DC power (discharge power) supplied from the assembled battery 20 into AC power and supplies the AC power to the motor generator 10 when the vehicle travels. Further, the inverter converts AC power generated by the motor generator 10 into DC power (charging power) and supplies it to the assembled battery 20 during regenerative braking of the vehicle. Thereby, the kinetic energy of the vehicle can be recovered as electric energy. Note that a DC / DC converter for boosting the voltage supplied from the assembled battery 20 or reducing the voltage supplied from the motor generator 10 may be included in the PCU 8.

  The regenerative braking described above refers to the case where power generation braking is performed according to the foot brake operation by the driver of the vehicle and the case where the foot brake operation is not performed but the power generation braking is performed by turning off the accelerator pedal during traveling. Including the case of decelerating (or stopping acceleration).

  The motor generator 10 receives AC power supplied from the PCU 8 and functions as an electric motor, and generates driving force for running the vehicle. Further, the motor generator 10 receives a driving force transmitted via the engine 9 or wheels (not shown), functions as a generator, and converts the kinetic energy of the vehicle into electric power for charging the assembled battery 20. .

  The engine 9 is an internal combustion engine that generates driving force by combustion of fuel such as gasoline, light oil, and methanol. The driving force generated by the engine 9 is transmitted to the wheels or the motor generator 10 via the power split mechanism 11.

  The power split mechanism 11 is a mechanism that transmits a driving force between the motor generator 10, the engine 9, and the wheels, and can be configured by, for example, a single pinion type planetary gear mechanism.

  When the engine 9 is started, the motor generator 10 receives the discharge power from the assembled battery 20 and generates driving force, whereby the engine 9 is cranked. As the engine 9 is cranked, fuel is injected and ignited, and the self-sustaining rotation of the engine 9 is established. The cranking of the engine 9 by the motor generator 10 is performed by transmitting the driving force generated by the motor generator 10 to the engine 9 via the power split mechanism 11.

  As described above, the discharge power of the assembled battery 20 is used to generate driving force by the motor generator 10. Further, the charging power of the assembled battery 20 is generated by the motor generator 10 that receives the driving force from the engine 9 or the kinetic energy of the vehicle. That is, charge / discharge control for the assembled battery 20 is performed by adjusting the discharge power and the charge power under the control of the motor generator 10 (or PCU 8) and the engine 9.

  On the other hand, the voltage sensor 12 detects the voltage of the assembled battery 20 and outputs the detection result to the control device 1. The current sensor 14 detects the current of the assembled battery 20 and outputs the detection result to the control device 1. The battery temperature sensor 16 detects the temperature (battery temperature) of the assembled battery 20 and outputs the detection result to the control device 1.

  The control device 1 acquires an SOC (State Of Charge) indicating the remaining capacity of the assembled battery 20 based on the detected voltage, current and battery temperature of the assembled battery 20. In the following description, as an example, the SOC is expressed as a percentage based on the full charge capacity of the assembled battery 20 as a reference (100%). Note that the SOC may be represented by the absolute value (Ah) of the remaining capacity instead of the expression by the percentage.

  Various well-known techniques can be used for the configuration for obtaining the SOC of the assembled battery 20. For example, the control device 1 sequentially detects the SOC by adding the provisional SOC calculated from the detected voltage (open circuit voltage value) in the open circuit state and the correction SOC calculated from the integrated value of the detected current. Can do. Further, the control device 1 calculates discharge allowable power (Wout) and charge allowable power (Win) based on the detected SOC of the assembled battery 20. The discharge allowable power (Wout) and the charge allowable power (Win) are limited values for a short time of the discharge power and the charge power at each time point, which are defined by the chemical reaction limit.

  On the other hand, the control device 1 is configured to receive an ignition off command (IGOFF) for stopping the vehicle system and an ignition on command (IGON) for starting the vehicle system. Here, the vehicle system includes each device constituting the vehicle such as the engine 9, and particularly includes a device that operates directly or indirectly with the electric power from the assembled battery 20.

  The outside air temperature sensor (information acquisition unit) 18 detects the outside air temperature of the vehicle and outputs the detection result to the control device 1. Based on the outside air temperature detected by the outside air temperature sensor 18, the control device 1 restarts the vehicle, in other words, the temperature of the assembled battery 20 when an ignition on command (IGON) is given (hereinafter, predicted battery). Temperature).

  Further, the control device 1 controls the charge / discharge amount of the assembled battery 20 based on the set control center value of the SOC. Specifically, the control device 1 outputs a control command to the PCU 8 to control the discharge amount of the assembled battery 20 and controls the driving force generated by the engine 9 via the engine ECU 7. The engine ECU 7 controls the driving force (number of rotations) generated by the engine 9 by adjusting the amount of fuel supplied to the engine 9 in accordance with a control command from the control device 1.

  When control device 1 receives the ignition-on command (IGON), control device 1 switches system relays SR1 and SR2 on. Thereby, the assembled battery 20 and the PCU 8 are electrically connected. On the other hand, when the control device 1 receives the ignition off command (IGOFF), the control device 1 switches off the system relays SR1 and SR2.

  The control device 1 is configured by, for example, an ECU (Electrical Control Unit), and includes a RAM (Random Access Memory) 4, a map 5, and a CPU (Central Processing Unit, controller) 6.

  The CPU 6 executes various processes of the control device 1 described above according to a program stored in the RAM 4 in advance. Then, the CPU 6 stores the data obtained along with the execution of the process in the RAM 4.

  The map 5 is composed of a data writable nonvolatile storage medium such as an EEPROM (Electrical Erasable and Programmable Read Only Memory), and stores the predicted battery temperature in association with the outside air temperature. Here, the CPU 6 refers to the map 5 and obtains a predicted battery temperature corresponding to the outside air temperature obtained from the outside air temperature sensor 18.

  As the predicted battery temperature stored in the map 5, a value (initial value) obtained in advance by experiments may be used, or a value obtained by updating this initial value by learning processing may be used. In the learning process, for example, the outside air temperature and the prediction stored in the map 5 based on the error between the predicted battery temperature acquired in advance and the outside temperature when the subsequent ignition on command (IGON) is given. The correspondence of battery temperature can be updated. Specifically, the value of the map 5 is updated so that the calculated value obtained by the calculation formula including the predicted battery temperature and the outside air temperature is associated with the outside air temperature used for obtaining the predicted battery temperature. Details regarding the learning process are described in Patent Document 1.

  Next, the process of the control apparatus 1 before stopping the vehicle of a present Example is demonstrated using FIG.

  In step S <b> 1, the CPU 6 acquires the outside air temperature based on the output of the outside air temperature sensor 18. In step S2, the CPU 6 uses the map 5 to acquire a predicted battery temperature corresponding to the outside air temperature acquired in step S1.

  In step S3, CPU6 sets the control center value of SOC used for charging / discharging control based on the estimated battery temperature acquired in step S2. Here, the CPU 6 controls charging / discharging of the assembled battery 20 based on the set control center value.

  Hereinafter, the process of setting the control center value will be described with reference to FIG. In FIG. 3, the vertical axis indicates discharge allowable power and charge allowable power, and the horizontal axis indicates the predicted battery temperature. The discharge allowable power is power (discharge amount) that enables discharge from the assembled battery 20, and the charge allowable power is power (charge amount) that enables charging of the assembled battery 20. FIG. 3 shows discharge characteristics when the SOC control center values are set to 40%, 60%, and 70%, and the SOC control center values are set to 40% and 60%. The charging characteristics are shown.

  The starting power (Ws) is the power required to start the vehicle system. That is, when the power output from the assembled battery 20 is lower than the starting power (Ws), the vehicle system cannot be started.

  On the other hand, as shown in FIG. 3, the higher the SOC control center value, the higher the allowable discharge power of the battery pack 20 and the lower allowable charge power. In other words, the lower the SOC control center value, the lower the discharge allowable power of the battery pack 20 and the higher the charge allowable power.

  Here, in the secondary battery, the charge characteristic and the discharge characteristic change according to the change in the control center value of the SOC. In particular, in a lithium ion battery, the amount of change in charge characteristics and discharge characteristics with respect to the change in control center value is large.

  The threshold value Ts shown in FIG. 3 is a lower limit value of the temperature required to start the vehicle system when the SOC control center value is set to 40%. That is, when the control center value of the SOC is set to 40%, if the predicted battery temperature predicted from the outside air temperature is lower than the threshold Ts, the output (discharge allowable power) of the assembled battery 20 is equal to the starting power Ws. The vehicle system cannot be started without reaching. On the other hand, when the control center value of the SOC is set to 40%, if the predicted battery temperature predicted from the outside air temperature is higher than the threshold value Ts, the output (discharge allowable power) of the assembled battery 20 is higher than the starting power Ws. And the vehicle system can be started.

  In this embodiment, before restarting the vehicle system, in other words, before stopping the vehicle system, based on the predicted battery temperature acquired in step S2 of FIG. 2 and the currently set control center value of the SOC. In addition, the control center value of the SOC is changed.

  For example, when the SOC control center value is currently set to 40% and the predicted battery temperature acquired in step S2 is lower than the threshold Ts, the control center value is changed from 40% to 60%. In this case, the assembled battery 20 is charged. By increasing the control center value in this way, the discharge allowable power of the assembled battery 20 can be increased, and when the vehicle system is restarted, power higher than the starting power Ws can be obtained from the assembled battery 20. it can. Thereby, the startability of a vehicle system can be improved.

  Here, in order to increase the control center value, it is sufficient to set a control center value with which the electric power equal to or higher than the starting electric power Ws can be obtained at the predicted battery temperature acquired in step S2. That is, it is only necessary to set a control center value having a discharge characteristic that intersects the starting power Ws or a control center value higher than the control center value at the predicted battery temperature acquired in step S2. As long as this condition is satisfied, the control center value can be set as appropriate.

  On the other hand, when the output (discharge allowable power) of the assembled battery 20 specified from the discharge characteristics of the currently set control center value and the predicted battery temperature is higher than the starting power Ws, the control center value is lowered. can do.

  For example, when the control center value is currently set to 60% and the predicted battery temperature acquired in step S2 is the threshold value Ts, the control center value can be changed from 60% to 40%. Thus, the charge amount with respect to the assembled battery 20 can be increased by lowering the control center value. That is, it is possible to efficiently charge the electric energy generated with the regenerative braking of the vehicle, and to improve the fuel efficiency of the vehicle. Even if the control center value is changed to 40%, the output of the battery pack 20 (discharge allowable power) becomes the starting power Ws, so that the vehicle system can be started.

  When lowering the control center value, it is necessary to set a control center value having a discharge characteristic that provides the starting power Ws at the predicted battery temperature acquired in step S2. Here, as described above, the vehicle system cannot be restarted at the control center value having a discharge characteristic in which the output (discharge allowable power) of the assembled battery 20 at the predicted battery temperature is lower than the starting power Ws. . Therefore, when lowering the control center value, it is necessary to select from among the control center value (one or more) having discharge characteristics in which the output of the assembled battery 20 at the predicted battery temperature is higher than the starting power Ws. As long as this condition is satisfied, the control center value can be set as appropriate.

  On the other hand, when the battery temperature is higher than the predetermined value, as shown in FIG. 3, the discharge allowable power and the charge allowable power of the assembled battery 20 almost do not change regardless of the control center value. Therefore, the setting of the control center value described above can be suitably used when the predicted battery temperature is lower than the predetermined value.

  In the present embodiment, the temperature of the assembled battery 20 when the vehicle system is restarted is predicted based on the temperature detected by the outside air temperature sensor 18 and the stored information in the map 5, but the present invention is not limited to this. is not. That is, it is only necessary to obtain information that can predict the temperature of the assembled battery 20 when the vehicle system is restarted.

  For example, the vehicle occupant can manually input the predicted battery temperature of the assembled battery 20. That is, if the predicted battery temperature of the assembled battery 20 can be specified by weather forecast or the like, the vehicle occupant can manually input the predicted battery temperature of the assembled battery 20. In this case, an input unit for inputting information indicating the predicted battery temperature and a determination unit (information acquisition unit) for determining information input by the input unit may be provided.

  Moreover, the outside temperature at the time of restarting a vehicle system is acquired via radio | wireless communication (information acquisition part), and the estimated battery temperature of the assembled battery 20 can also be specified based on this outside temperature. For example, the outside air temperature at a specific date and time can be acquired via a wireless communication from a database storing predicted future outside air temperatures. And the estimated battery temperature of the assembled battery 20 can be specified from the acquired external temperature. Further, by using a GPS (Global Positioning System) function together, it is possible to acquire the outside air temperature at a specific location.

  On the other hand, in the present embodiment, the correspondence relationship between the outside air temperature and the predicted battery temperature of the assembled battery 20 is stored in the map 5 in the control device 1, but is not limited thereto. For example, the correspondence relationship between the outside air temperature and the predicted battery temperature of the assembled battery 20 is stored in a database provided at a location away from the vehicle, and stored in the database via wireless communication as necessary. It is also possible to obtain information on correspondence relationships. With this configuration, it is not necessary to provide the map 5 in the control device 1.

1 is a block diagram illustrating a partial configuration of a vehicle that is Embodiment 1 of the present invention. FIG. 6 is a flowchart illustrating processing for setting a control center value in the first embodiment. It is a figure which shows the relationship between estimated battery temperature, discharge allowable power of a battery pack, and charge allowable power.

Explanation of symbols

1: Control device 6: CPU (controller)
9: Engine (part of vehicle system)
18: Outside temperature sensor (information acquisition unit)
20: assembled battery (power storage device)

Claims (7)

A control device that is mounted on a vehicle and controls charging and discharging of a power storage device,
A controller that changes a control center value used to control the state of charge of the power storage device;
An information acquisition unit for acquiring information for predicting the temperature of the power storage device when restarting the system of the vehicle;
The controller sets the control center value so that an output of the power storage device at a predicted temperature predicted from acquisition information of the information acquisition unit is equal to or higher than a starting power for restarting the system. Control device.   The controller is configured to increase the output of the power storage device when the output of the power storage device obtained by the discharge control at the currently set control center value is lower than the starting power at the predicted temperature. The control device according to claim 1, wherein the control center value is changed.   The control device according to claim 2, wherein the controller permits charging of the power storage device by changing the control center value in a direction in which the output of the power storage device increases.   The controller is configured to increase the chargeable amount of the power storage device within a range in which the output of the power storage device at the predicted temperature obtained by the discharge control at the control center value is equal to or higher than the starting power. The control device according to claim 1, wherein the control center value is changed.   5. The control device according to claim 4, wherein the controller allows the discharge of the power storage device by changing the control center value in a direction in which an amount that can be charged to the power storage device increases. .   The control device according to any one of claims 1 to 5, wherein the power storage device is configured by a lithium ion battery. A vehicle comprising the control device according to any one of claims 1 to 6.

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