JP2007171044A - Controller for battery, motor vehicle, and control method of secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a battery, a motor vehicle, and a secondary battery capable of suppressing reduction in the calculation precision of SOC (state of charge). <P>SOLUTION: The controller for the battery for controlling the input/output of the secondary battery 10, mounted in a vehicle having a motor as a power source comprises a first SOC calculation section 3, a second SOC calculation section 4, and a determining section 5. The first SOC calculation section 3 integrates the current during charge and discharge of the secondary battery 10 and calculates a first estimated SOC of the secondary battery 10. The second SOC calculation section 4 calculates a second estimated SOC of the secondary battery 10, based on the charge and discharge history of the secondary battery 10. The determining section 5 compares the first estimated SOC with the second estimated SOC, and, when the difference is larger than the reference value, commands a controller for the vehicle (vehicle ECU 20) for controlling the motor driving to drive the motor, in order to make the variation width of the SOC of the secondary battery 10 larger. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a battery control device that controls input / output of a secondary battery, an electric vehicle including the same, and a method for controlling a secondary battery.

  In recent years, secondary batteries are sometimes combined with fuel cells, solar cells, and generators and used as power supply systems. The generator is driven by natural forces such as wind power or hydraulic power or artificial power such as an internal combustion engine. The power supply system combining such secondary batteries aims to improve energy efficiency by storing surplus power in the secondary battery.

  As an example of such a system, in recent years, a hybrid vehicle (“HEV”) that includes an engine and a motor as power sources can be cited. When the output from the engine is larger than the power required for traveling, the HEV drives the generator with surplus power and charges the secondary battery. The HEV also charges the secondary battery by driving a motor with wheels and using the motor as a generator during braking or deceleration of the vehicle. On the contrary, when the output from the engine is small, the HEV drives the motor by discharging the secondary battery in order to compensate for the insufficient power.

  As described above, in the HEV, energy that has been released into the atmosphere as heat in a conventional vehicle can be stored in a secondary battery, so that energy efficiency can be improved and fuel consumption can be dramatically improved compared to a conventional vehicle. Can be improved.

  In addition, the secondary battery has a problem that battery performance deteriorates when overdischarge or overcharge is performed. For this reason, in the HEV, a battery control device (hereinafter referred to as “battery ECU: Electric Control Unit”) calculates the remaining battery level (SOC: State of Charge) of the secondary battery, and based on the obtained SOC. To control the charge / discharge (input / output) of the secondary battery. In general, the battery ECU controls charging / discharging so that the SOC is within a range of 40% to 70%. At this time, it is important to accurately calculate the SOC.

  The following two methods are known as conventional SOC calculation methods. One calculation method is a method of calculating the SOC by integrating currents during charging and discharging of the secondary battery (see, for example, Patent Document 1 and Patent Document 2). In this method, first, the battery ECU measures the current value of the charged / discharged current (minus when charging and plus when discharging), and the measured current value is the current (−) during charging. If so, multiply the charging efficiency. Next, the battery ECU calculates the integrated capacity by integrating the obtained current value (multiplied value in the case of charging) over a set time. Next, the battery ECU calculates the SOC based on the obtained accumulated capacity.

  Another calculation method is a method of calculating the SOC based on the charge / discharge history (see, for example, Patent Document 1). In this method, first, the battery ECU acquires a plurality of pair data of the charged / discharged current I and the terminal voltage V for each battery block, and stores these as charge / discharge history. Next, the battery ECU selects average pair data of the representative battery block from the pair data stored as the charge / discharge history (pair data). Further, the battery ECU obtains a first-order approximation line (voltage V-current I approximation line) from the selected pair data using a regression analysis method.

  Next, the battery ECU obtains a voltage value (voltage V-current I approximate straight line intercept) corresponding to the current value 0 (zero), and sets this as the no-load voltage OCV of the representative battery block. Further, the battery ECU obtains a change amount ΔQ per unit time of the integrated capacity, and performs a time delay process and an averaging process on the change amount ΔQ, thereby corresponding to an unnecessary high-frequency component of ΔQ. ΔQ ′ is calculated by removing the fluctuation component. Further, the battery ECU sets the temperature as the vertical axis (or horizontal axis), ΔQ ′ as the horizontal axis (or vertical axis), and a two-dimensional map in which the polarization voltage corresponding to the intersection of the vertical axis and the horizontal axis is recorded. The polarization voltage is specified by applying the calculated change ΔQ ′ and the minimum battery temperature.

  Next, the battery ECU calculates the electromotive force of the representative battery block by subtracting the estimated polarization voltage from the representative no-load voltage OCV. Furthermore, the battery ECU calculates the temperature on the two-dimensional map in which the vertical axis (or horizontal axis), the electromotive force as the horizontal axis (or vertical axis), and the SOC corresponding to the intersection of the vertical axis and the horizontal axis are recorded. The SOC is specified by applying the generated electromotive force and the minimum battery temperature.

Moreover, in HEV, in order to raise the calculation precision of SOC, battery ECU is implementing both the SOC calculation method by above-mentioned electric current integration, and the SOC calculation method based on above-mentioned charging / discharging log | history information. In this case, the battery ECU compares both results and corrects the value obtained in the former based on the value obtained in the latter (see, for example, Patent Document 3).
JP 2003-197275 A JP 2004-47279 A JP 2003-149307 A

  However, when the two SOC calculation methods are implemented, a large deviation may occur between these calculation results. For example, when the secondary battery is removed from the vehicle for repair or when it is replaced with a new secondary battery, the charge / discharge history of the battery ECU is initialized. In this case, the calculation accuracy of the SOC calculation method based on the charge / discharge history is lowered, and the above-described deviation occurs.

  Furthermore, when the vehicle is left for a long period of time, a large difference occurs between the actual polarization voltage and the polarization voltage obtained from the polarization information. In this case as well, the calculation accuracy of the SOC calculation method based on the charge / discharge history is high. The above-described deviation occurs.

  In addition, when such a deviation occurs, an error occurs between the calculated value of the SOC calculated by the battery ECU and the actual SOC value of the secondary battery, as shown in FIG. , SOC calculation accuracy is reduced. Furthermore, since the conventional battery ECU performs correction based on the SOC calculated from the charge / discharge history, if the charge / discharge history is not accurate, the deviation gradually increases, and the SOC calculation accuracy is greatly reduced. In addition, a decrease in SOC calculation accuracy causes a decrease in the life of the secondary battery.

  FIG. 5 is a diagram showing SOC fluctuations in a secondary battery equipped with a conventional battery ECU. In FIG. 5, the vertical axis indicates SOC [%] and SOC error [%], and the horizontal axis indicates time [s]. In FIG. 5, “SOC calculated value” indicates the SOC calculated by correcting the SOC obtained from the current integration based on the SOC obtained from the charge / discharge history. “SOC true value” indicates the SOC obtained by actual measurement. “SOC error” indicates an error of the calculated SOC value with respect to the true SOC value.

  An object of the present invention is to provide a battery control device, an electric vehicle, and a secondary battery control method capable of solving the above problems and suppressing a decrease in SOC calculation accuracy.

  In order to achieve the above object, a first battery control device according to the present invention is a battery control device that controls input / output of a secondary battery, and includes a first SOC calculation unit and a second SOC calculation unit. And a determination unit, wherein the first SOC calculation unit calculates a first estimated SOC of the secondary battery by integrating currents during charging and discharging of the secondary battery, and the second SOC The SOC calculation unit calculates a second estimated SOC of the secondary battery based on the charge / discharge history of the secondary battery, and the determination unit calculates the first estimated SOC and the second estimated SOC. If the difference is larger than a reference value, the device using the secondary battery is instructed to use the secondary battery to increase the SOC fluctuation range of the secondary battery. It is characterized by.

  In order to achieve the above object, a second battery control device according to the present invention is a battery control device that controls input / output of a secondary battery, and includes a determination unit, and the determination unit includes the second battery control device. It is determined whether or not the charge / discharge history used for calculating the SOC of the secondary battery is initialized, and when the charge / discharge history is initialized, the secondary battery is used for a device that uses the secondary battery. The secondary battery is instructed to increase the fluctuation range of the SOC.

  In order to achieve the above object, a first electric vehicle according to the present invention is an electric vehicle including a motor as a power source, a secondary battery, and a battery control device that controls input and output of the secondary battery; A vehicle control device that controls driving of the motor, and the battery control device includes a first SOC calculation unit, a second SOC calculation unit, and a determination unit, and the first SOC calculation unit. The unit calculates the first estimated SOC of the secondary battery by accumulating the current during charging and discharging of the secondary battery, and the second SOC calculating unit calculates the charge / discharge history of the secondary battery. A second estimated SOC of the secondary battery is calculated based on the first estimated SOC, and the determination unit compares the first estimated SOC with the second estimated SOC, and a difference between them is larger than a reference value. In addition, the vehicle control device outputs a signal to the vehicle control device. Wherein the decision unit outputs the signal, characterized in that the fluctuation range of SOC of the secondary battery to drive the motor so as to increase.

  In order to achieve the above object, a second electric vehicle according to the present invention is an electric vehicle including a motor as a power source, and a secondary battery and a battery control device that controls input / output of the secondary battery. And a vehicle control device that controls driving of the motor, wherein the battery control device includes a determination unit, and the determination unit uses the charge / discharge history used for calculating the SOC of the secondary battery. When it is determined whether or not the charge / discharge history is initialized, a signal is output to the vehicle control device, and the vehicle control device outputs the signal when the determination unit outputs the signal. The motor is driven such that the fluctuation range of the SOC of the secondary battery is increased.

  In order to achieve the above object, a first control method in the present invention is a control method for controlling input / output of a secondary battery, and (a) integrates currents during charging and discharging of the secondary battery. Calculating a first estimated SOC of the secondary battery, and (b) calculating a second estimated SOC of the secondary battery based on a charge / discharge history of the secondary battery; c) a step of comparing the first estimated SOC and the second estimated SOC; and (d) if the difference in the comparison in the step (c) is greater than a reference value, the two And a step of instructing a device using the secondary battery to use the secondary battery to increase the fluctuation range of the SOC of the secondary battery.

  In order to achieve the above object, the second control method in the present invention is a control method for controlling input / output of a secondary battery, wherein the second control method in the invention is (a) the second control method. A step of determining whether or not the charge / discharge history used for calculating the SOC of the secondary battery has been initialized; and (b) when the charge / discharge history is initialized as a result of the determination in the step (a), And a step of instructing a device using the secondary battery to use the secondary battery to increase the fluctuation range of the SOC of the secondary battery.

  In order to achieve the above object, a first program according to the present invention is a program for causing a computer to execute input / output control of a secondary battery, and (a) integrates current during charging and discharging of the secondary battery. Calculating a first estimated SOC of the secondary battery; and (b) calculating a second estimated SOC of the secondary battery based on a charge / discharge history of the secondary battery; (C) comparing the first estimated SOC and the second estimated SOC; and (d) as a result of the comparison in the step (c), when these differences are larger than a reference value, A step of instructing a device using the secondary battery to use the secondary battery to increase the fluctuation range of the SOC of the secondary battery.

  In order to achieve the above object, a second program according to the present invention is a program for causing a computer to execute input / output control of a secondary battery, the program comprising: (a) the SOC of the secondary battery A step of determining whether or not a charge / discharge history used for calculation of the battery is initialized; and (b) if the charge / discharge history is initialized as a result of the determination in the step (a), the secondary battery is Instructing a device to be used to instruct the use of the secondary battery to increase the fluctuation range of the SOC of the secondary battery.

  As described above, according to the present invention, when the accuracy of calculating the SOC of the secondary battery is reduced, the secondary battery is configured so that the fluctuation range of the SOC of the secondary battery is increased in the device using the secondary battery. used. In this case, since the distribution of the pair data stored as the charge / discharge history is wider than before, the calculation accuracy of the polarization voltage is improved, and as a result, the calculation accuracy of the SOC from the charge / discharge history is also improved. For this reason, the SOC (first estimated SOC) calculated by integrating the currents during charging / discharging of the secondary battery, and the SOC (second estimated SOC) calculated based on the charging / discharging history of the secondary battery. The deviation between the two becomes smaller. Therefore, the error of the SOC calculated value (the value of the first estimated SOC corrected based on the second estimated SOC) with respect to the SOC true value converges to 0 (zero). According to the present invention, it is possible to suppress a decrease in SOC calculation accuracy.

  From this fact, if the present invention is applied to a vehicle equipped with a motor such as HEV as a power source, the SOC can be obtained even when the secondary battery is changed or the vehicle is left for a long time. A decrease in the calculation accuracy of can be suppressed.

  Furthermore, the present invention can also be applied to a power supply system configured by combining a secondary battery with an independent power source such as a fuel cell, a solar cell, and a generator other than the vehicle. In these power supply systems, even when the secondary battery is replaced or left for a long period of time, a decrease in the SOC calculation accuracy can be suppressed.

  A first battery control device according to the present invention is a battery control device that controls input / output of a secondary battery, and includes a first SOC calculation unit, a second SOC calculation unit, and a determination unit. The first SOC calculator calculates the first estimated SOC of the secondary battery by accumulating the current during charging and discharging of the secondary battery, and the second SOC calculator Based on the charging / discharging history of the secondary battery, a second estimated SOC of the secondary battery is calculated, and the determination unit compares the first estimated SOC with the second estimated SOC, and When the difference is larger than a reference value, the apparatus using the secondary battery is instructed to use the secondary battery to increase the SOC fluctuation range of the secondary battery.

  In the first battery control device according to the present invention, the determination unit further determines whether or not the charge / discharge history is initialized, and the device also includes the case where the charge / discharge history is initialized. On the other hand, it is possible to adopt a mode in which the use of the secondary battery for increasing the fluctuation range of the SOC of the secondary battery is instructed.

  The second battery control device according to the present invention is a battery control device that controls input / output of a secondary battery, and includes a determination unit, which is used for calculating the SOC of the secondary battery. It is determined whether the charge / discharge history is initialized, and when the charge / discharge history is initialized, the device using the secondary battery increases the SOC fluctuation range of the secondary battery. The use of a secondary battery is instructed.

  A first electric vehicle according to the present invention is an electric vehicle including a motor as a power source, and controls a secondary battery, a battery control device that controls input / output of the secondary battery, and driving of the motor. A control apparatus for a vehicle, wherein the battery control apparatus includes a first SOC calculation unit, a second SOC calculation unit, and a determination unit, and the first SOC calculation unit includes the secondary battery. And calculating a first estimated SOC of the secondary battery, and the second SOC calculating unit calculates the secondary battery based on a charge / discharge history of the secondary battery. The second estimated SOC is calculated, and the determination unit compares the first estimated SOC with the second estimated SOC, and when the difference between them is larger than a reference value, the vehicle control device A signal is output to the vehicle control device, wherein the determination unit outputs the signal. When a force, characterized in that the fluctuation range of SOC of the secondary battery to drive the motor so as to increase.

  In the first electric vehicle according to the present invention, the determination unit determines whether or not the charge / discharge history is initialized, and the vehicle control apparatus also includes the case where the charge / discharge history is initialized. In this manner, a signal can be output.

  The second electric vehicle according to the present invention is an electric vehicle including a motor as a power source, the secondary battery, a battery control device for controlling input / output of the secondary battery, and driving of the motor. A control device for a vehicle that controls, the control device for a battery includes a determination unit, and the determination unit determines whether or not the charge / discharge history used for calculating the SOC of the secondary battery has been initialized. When the charge / discharge history is initialized, the vehicle control device outputs a signal to the vehicle control device. When the determination unit outputs the signal, the vehicle control device outputs the SOC of the secondary battery. The motor is driven so that the fluctuation range increases.

  A first control method according to the present invention is a control method for controlling input / output of a secondary battery, wherein (a) the current during charging / discharging of the secondary battery is integrated, Calculating a first estimated SOC; (b) calculating a second estimated SOC of the secondary battery based on a charge / discharge history of the secondary battery; and (c) the first estimate. A step of comparing the SOC and the second estimated SOC; and (d) if the difference in the step (c) is greater than a reference value, the device using the secondary battery is compared. On the other hand, the method includes at least a step of instructing the use of the secondary battery to increase the fluctuation range of the SOC of the secondary battery.

  In the first control method of the present invention, it is determined whether the charge / discharge history is initialized, and when the charge / discharge history is initialized, the secondary battery is It can be set as the aspect which further has the process of instruct | indicating use of the said secondary battery which increases the fluctuation range of SOC.

  A second control method according to the present invention is a control method for controlling input / output of a secondary battery, and (a) a charge / discharge history used for calculating the SOC of the secondary battery is initialized. (B) When the charge / discharge history is initialized as a result of the determination in the step (a), with respect to the device using the secondary battery, And a step of instructing the use of the secondary battery to increase the fluctuation range of the SOC.

  The present invention may be a program for embodying the first control method or the second control method in the present invention. By installing and executing this program on a computer, the first control method or the second control method in the present invention is executed.

(Embodiment)
Hereinafter, a control device for a battery, an electric vehicle, and a control method for a secondary battery according to an embodiment of the present invention will be described with reference to FIGS. Initially, the structure of the electric vehicle in this Embodiment is demonstrated using FIG.

  FIG. 1 is a diagram showing a schematic configuration of an electric vehicle according to an embodiment of the present invention. The electric vehicle in the present embodiment is an HEV. As shown in FIG. 1, the electric vehicle includes an engine 24 and a motor 26 as a power source that transmits power to the front wheels 28, and a secondary battery 10 as a power supply source to the motor 26.

  The engine 24 transmits power to the front wheels 28 via a transmission 25, a speed reducer 27, and a drive shaft 30. Further, the motor 26 transmits power to the front wheels 28 via the speed reducer 27 and the drive shaft 30. In addition, when the secondary battery 10 needs to be charged, a part of the power of the engine 24 is transmitted to the generator 23 via the transmission 25. Reference numeral 29 denotes a rear wheel, and reference numeral 31 denotes a shaft 31 that connects the left and right rear wheels 29.

  The electric power generated by the generator 23 is supplied to the secondary battery 10 through the power unit 22 and used for charging. Further, when the electric vehicle is decelerated or braked, the motor 26 is used as a generator. The electric power generated by the motor 26 is also supplied to the secondary battery 10 via the power unit 22 and used for charging.

  In addition, the electric vehicle has, as control devices, a battery control device (battery ECU) 1 that controls input / output (charge / discharge) of the secondary battery 10 and a vehicle control device (vehicle ECU) that controls driving of the motor 26. 20 and an engine control device (engine ECU) 21 for controlling the ignition timing, fuel injection amount, and the like of the engine. Among these, the battery ECU 1 will be described later with reference to FIG.

  The vehicle ECU 20 controls the air conditioner and various instruments in addition to the drive control of the motor 26 mounted on the vehicle. Further, the vehicle ECU 20 receives from the battery ECU 1 a signal for specifying the upper limit value (output limit value) of the discharge power of the secondary battery 10 and a signal for specifying the SOC of the secondary battery 10 calculated by the battery ECU 1. The The vehicle ECU 20 requests output from the battery ECU 1 so that the output limit value is not exceeded and the SOC is set within the set range.

  The power unit 22 includes an inverter (not shown) that converts direct current from the secondary battery 10 into alternating current for driving the motor, and a DC / DC converter that converts the direct current to 12V. In addition, the power unit 22 includes a booster circuit.

  Next, the configuration of the battery control device in the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing a schematic configuration of the battery control device in the embodiment of the present invention. As shown in FIG. 2, the battery ECU 1 (battery control device) mainly includes a control unit 2, a storage unit 6, a voltage measurement unit 7, a current measurement unit 8, and a temperature measurement unit 9. Yes.

In the first embodiment, the secondary battery 10 is configured by connecting battery blocks B _{1 to} B ₂₀ in series. The battery blocks B _{1 to} B ₂₀ are accommodated in the battery case 12. In addition, each of the battery blocks B _{1 to} B ₂₀ is configured by electrically connecting two battery modules in series, and each battery module is configured by electrically connecting six unit cells 11 in series. Connected and configured. As each single battery 11, a nickel metal hydride battery, a lithium ion battery, etc. can be used. In addition, the number of battery blocks, battery modules, and single cells 11 is not particularly limited. The configuration of the secondary battery 10 is not limited to the above example.

  A plurality of temperature sensors 13 are arranged in the battery case 12 in order to measure the temperature of the secondary battery 10. The arrangement of the plurality of temperature sensors 13 is one per group, with a plurality of battery blocks having relatively close temperatures as one group, or one battery block having a relatively different temperature from any battery block as one group. This is done by arranging two temperature sensors 13. The grouping is performed by measuring the temperature of each battery block by a prior experiment or the like.

The voltage measuring unit 7 measures the terminal voltage of the secondary battery 10. In this embodiment, the voltage measurement unit 7 measures the battery block B ₁ .about.B ₂₀ each terminal voltages Vu ₁ ~Vu _20. Further, the voltage measuring unit 3 generates voltage data for specifying the terminal voltages Vu _{1 to} Vu ₂₀ and outputs this to the control unit 2.

  When the voltage data is output, the control unit 2 stores the voltage data in the storage unit 6 and specifies the lowest terminal voltage (minimum terminal voltage) Vu_min among the terminal voltages Vu for each battery block. The voltage measurement unit 7 outputs voltage data to the control unit 2 at a preset cycle.

  The current measuring unit 8 measures the current I output when the secondary battery 10 is charged and discharged. In the present embodiment, the current measuring unit 8 converts an analog signal output from a current sensor (not shown) into a digital signal. Furthermore, the current measuring unit 8 specifies the current value I of the current input to the secondary battery 10 during charging and the current value I of the current output from the secondary battery 10 during discharging based on this digital signal. Current data to be generated is output to the control unit 2.

  Further, the current measuring unit 8 generates current data with the charge time being negative and the discharge time being positive. The output of current data to the control unit 2 by the current measuring unit 8 is also performed at a preset cycle. When the current data is output, the control unit 2 stores the current data in the storage unit 6.

  The temperature measurement unit 9 measures the temperature of the secondary battery 10. In the present embodiment, the temperature measurement unit 9 converts analog signals output from the plurality of temperature sensors 13 arranged in the battery case 12 into digital signals, and based on this, converts the battery temperature of the secondary battery 10. Temperature data to be identified is generated and output to the control unit 2.

  When the temperature data is output, the control unit 2 stores the temperature data in the storage unit 6 and specifies the lowest battery temperature (minimum battery temperature) from among the battery temperatures for each group. The output of temperature data to the control unit 2 by the temperature measurement unit 9 is also performed at a preset cycle.

  The control unit 2 includes a first SOC calculation unit 3, a second SOC calculation unit 4, and a determination unit 5. The first SOC calculation unit 3 calculates the first estimated SOC of the secondary battery 10 by integrating the current I measured by the current measurement unit 8. Further, the second SOC calculation unit 4 calculates a second estimated SOC based on the charge / discharge history of the secondary battery 10.

  Specifically, the first SOC calculation unit 3 first reads the current data stored in the storage unit 6 to acquire the current value I, and the acquired current value I is the current (−) during charging. If so, multiply the charging efficiency. Next, the first SOC calculation unit 3 calculates the integrated capacity Q by integrating the obtained current value I (multiplied value in the case of charging) over a set time. Next, the first SOC calculation unit 3 obtains the difference between the fully charged capacity and the accumulated capacity Q obtained in advance by experiments, and then obtains the ratio of the difference with respect to the fully charged capacity. The ratio (%) is estimated as the first SOC (first estimated SOC).

  In addition, the second SOC calculation unit 4 first determines the terminal voltage for each battery block from the voltage data output from the voltage measurement unit 7 and the current data output from the current measurement unit 8 within the set period. A plurality of pair data of the current value I and the current value I of the current during charging / discharging are acquired. The acquired pair data is stored in the storage unit 6 as a charge / discharge history.

  Next, the second SOC calculation unit 4 selects the average pair data of the representative battery block from the pair data for each battery block stored in the storage unit 6. Further, the second SOC calculation unit 4 obtains a first-order approximate line (VI approximate line) from the selected pair data using a regression analysis method. Next, the 2nd SOC calculation part 4 calculates | requires V intercept of VI approximate line as no-load voltage OCV, and makes this the no-load voltage OCV of the battery block which becomes a representative.

  Next, the second SOC calculation unit 4 calculates the polarization voltage Vp of the secondary battery 10 based on the change amount ΔQ per unit time of the accumulated capacity Q. Specifically, the second SOC calculation unit 4 performs a time delay process and an averaging process on the change amount ΔQ, thereby removing a fluctuation component corresponding to an unnecessary high-frequency component of ΔQ, ΔQ ′ is calculated. Further, the second SOC calculation unit 4 records the polarization voltage corresponding to the intersection of the vertical axis and the horizontal axis with the temperature as the vertical axis (or horizontal axis) and ΔQ ′ as the horizontal axis (or vertical axis). The calculated change amount ΔQ ′ and the minimum battery temperature are applied to the two-dimensional map to specify the polarization voltage. The second SOC calculation unit 4 estimates the specified polarization voltage as the polarization voltage Vp of the secondary battery 10. This two-dimensional map is stored in the storage unit 6.

  Next, the second SOC calculation unit 4 subtracts the estimated polarization voltage Vp from the representative no-load voltage OCV to calculate the electromotive force of the representative battery block. Further, the second SOC calculation unit 4 sets the temperature on the vertical axis (or horizontal axis), the electromotive force on the horizontal axis (or vertical axis), and records the SOC corresponding to the intersection of the vertical axis and the horizontal axis. By applying the calculated electromotive force and the minimum battery temperature to the dimension map, the SOC is specified, and this is estimated as the second SOC (second estimated SOC). This two-dimensional map is also stored in the storage unit 6.

  The determination unit 5 determines whether the difference between the first estimated SOC and the second estimated SOC is smaller than the reference value α. When the difference between the first estimated SOC and the second estimated SOC is smaller than the reference value α, the determination unit 5 corrects the first estimated SOC based on the second estimated SOC, and the corrected first Is the SOC of the secondary battery 10. In this case, determination unit 5 notifies vehicle ECU 20 of the obtained SOC.

  Further, the correction of the first estimated SOC is performed by multiplying the first estimated SOC by a correction coefficient according to the difference between the first estimated SOC and the second estimated SOC, or by changing the predetermined value to the first estimated SOC. This can be done by adding to the SOC. In addition, said correction coefficient and said predetermined value can be calculated | required by performing a charging / discharging experiment etc. previously.

  On the other hand, the determination unit 5 determines that the difference between the first estimated SOC calculated by the first SOC calculation unit 3 and the second estimated SOC calculated by the second SOC calculation unit 4 is larger than the reference value α. Instructs the vehicle ECU 20 (see FIG. 1) to improve this state. Specifically, the determination unit 5 transmits an instruction signal to the vehicle ECU 20 to drive the motor 26 so that the fluctuation range of the SOC increases compared to a normal case. In this case, the vehicle ECU 20 drives the motor 26 in accordance with an instruction from the determination unit 5.

  Further, in the present embodiment, the reference value α is an index that represents the state of the battery such as the age of use of the secondary battery 10 and an index that represents the state of the battery pack such as the total number of cells of the secondary battery 10 and temperature variations. It is set appropriately based on this. Specifically, the reference value α is set to 10% to 30%.

  Further, in the present embodiment, determination unit 5 also determines whether or not the charge / discharge history used for calculating the second estimated SOC has been initialized. Specifically, in this embodiment, when the charge / discharge history is initialized at the time of vehicle repair or the like, or when the battery ECU 1 is replaced together with the secondary battery 10, the vehicle ECU 20 stores that fact, and at the time of startup An initialization signal is input to the battery ECU 1. The determination unit 5 determines whether or not it has been initialized based on an initialization signal from the vehicle ECU 20. Even when the charge / discharge history is initialized, determination unit 5 instructs vehicle ECU to drive motor 26 that increases the fluctuation range of the SOC more than usual.

  In the present embodiment, the “SOC fluctuation range” refers to the difference between the maximum value and the minimum value of the SOC within a set time. For example, this time is preferably set within 5 minutes. The “normal case” means a state in which the vehicle ECU 20 controls the driving of the motor 26 so that the SOC fluctuates around ± 10% with respect to the control center (for example, 50%). Specifically, it means a state in which the vehicle ECU 20 is driving the motor 26 so that the SOC fluctuates in the range of 40% to 60%.

  Further, the increase amount of the SOC fluctuation range after the instruction by the determination unit 5 is not particularly limited. However, for example, if the normal SOC fluctuation range is set to 45% to 55%, the SOC fluctuation range after the instruction by the determination unit 5 is 43% to 57%, particularly 35% to 75%. % Is preferably set.

  Next, a method for controlling the secondary battery in the embodiment of the present invention will be described with reference to FIGS. The secondary battery control method in the present embodiment is implemented by operating battery ECU (battery control device) 1 in the present embodiment shown in FIG. Therefore, the following description will be made based on the operation of the battery ECU 1 shown in FIG.

  FIG. 3 is a flowchart showing a control method of the secondary battery in the embodiment of the present invention. FIG. 4 is a diagram showing a change in SOC of the secondary battery in the embodiment of the present invention. In FIG. 4, the vertical axis indicates SOC [%] and SOC error [%], and the horizontal axis indicates time [s]. In FIG. 4, the “SOC calculated value” indicates the first estimated SOC corrected based on the second estimated SOC. “SOC true value” indicates the SOC obtained by actual measurement. “SOC error” indicates an error of the calculated SOC value with respect to the true SOC value.

  As shown in FIG. 3, first, the determination unit 5 determines whether an initialization process has been performed on the charge / discharge history stored in the storage unit 6. When the initialization process is performed, the determination unit 5 executes Step S6 described later.

  When the initialization process has not been performed, the determination unit 5 causes the first SOC calculation unit 3 to calculate the first estimated SOC (SOC (I)) (step S2), and the second SOC calculation. The unit 4 is caused to calculate the second estimated SOC (SOC (V)) (step S3).

  Next, the determination unit 5 determines whether or not the absolute value of the difference between the SOC (I) and the SOC (V) is smaller than the reference value α (step S4). If the absolute value of the difference between the SOC (I) and the SOC (V) is smaller than the reference value α as a result of the determination, the determination unit 5 corrects the SOC (I) based on the SOC (V). Is stored in the storage unit 6 as the SOC of the secondary battery 10. Thereafter, determination unit 5 notifies vehicle ECU 20 (see FIG. 1) of the stored SOC and ends the process.

  On the other hand, if the absolute value of the difference between SOC (I) and SOC (V) is greater than the reference value α as a result of determination, determination unit 5 executes step S6. In step S <b> 6, determination unit 5 transmits an instruction signal to vehicle ECU 20 to increase the SOC fluctuation range as compared with a normal case.

  Thereafter, the determination unit 5 causes the first SOC calculation unit 3 to calculate SOC (I) again (step S7), and causes the second SOC calculation unit 4 to calculate SOC (V) (step S7). S8) Step S4 is executed again.

  As a result of the execution of steps S1 to S8, the difference between the SOC (I) and the SOC (V) gradually approaches the reference value α. Therefore, as shown in FIG. 4, the SOC error with respect to the true SOC value of the calculated SOC value is shown. Converges to 0 (zero).

  As described above, in the present embodiment, when a large deviation occurs between the first estimated SOC and the second estimated SOC and the calculation accuracy of the secondary battery 10 is likely to decrease, the vehicle ECU 20 Then, the motor is driven to greatly change the SOC. In addition, when the charge / discharge history is initialized, the vehicle ECU 20 drives the same motor. For this reason, the gap between the first estimated SOC and the second estimated SOC is eliminated, and a decrease in the calculation accuracy of the secondary battery 10 is suppressed.

  In addition, the battery control device (battery ECU) in the present embodiment can be realized by installing a program for implementing various processes shown in FIG. 3 in a microcomputer and executing the program. In this case, a CPU (central processing unit) of the microcomputer functions as the control unit 2. In addition, the voltage sensor connection circuit and the CPU function as the voltage measurement unit 7, the current sensor connection circuit and the CPU function as the current measurement unit 8, and the temperature sensor 9 connection circuit and the CPU measure the temperature. It functions as part 5. Further, various memories provided in the microcomputer function as the storage unit 6.

  Furthermore, in the field of HEV, a mode in which the vehicle ECU also functions as a battery ECU can be considered. In this aspect, the battery control device 1 according to the present embodiment is realized by installing a program that embodies various processes shown in FIG. 3 in a microcomputer constituting the vehicle ECU 20 and executing the program. can do.

  Moreover, in said embodiment, the determination part 5 of the control apparatus 1 for batteries is determining about the magnitude of the difference of 1st estimated SOC and 2nd estimated SOC, and the presence or absence of the initialization process. However, the present invention is not limited to this embodiment. For example, the determination unit 5 may perform only one of the above two determinations.

  Moreover, although said embodiment demonstrated the example which applied the control apparatus for secondary batteries of this invention and the output limiting method of a secondary battery to HEV, this invention is limited to this example. is not. The secondary battery control device and the secondary battery output limiting method according to the present invention are driven by a natural power such as a fuel cell, a solar cell, or an artificial power other than an automobile engine, or wind and hydraulic power. The present invention can also be applied to a power supply system that combines a generator and a secondary battery.

  The battery control device and the secondary battery control method according to the present invention include a vehicle including a motor as a power source, and a power source that combines a secondary battery and a stand-alone power source such as a fuel cell, a solar cell, or a generator. It is also effective for the system. In addition, the electric vehicle according to the present invention is effective for HEV. The battery control device, the electric vehicle, and the secondary battery control method in the present invention have industrial applicability.

It is a figure which shows schematic structure of the electric vehicle in embodiment of this invention. It is a figure which shows schematic structure of the control apparatus for batteries in embodiment of this invention. It is a flowchart which shows the control method of the secondary battery in embodiment of this invention. It is a figure which shows the fluctuation | variation of SOC of the secondary battery in embodiment of this invention. It is a figure which shows the fluctuation | variation of SOC in a secondary battery provided with the conventional battery ECU.

Explanation of symbols

1 Battery ECU (Battery control device)
DESCRIPTION OF SYMBOLS 2 Control part 3 1st SOC calculation part 4 2nd SOC calculation part 5 Judgment part 6 Memory | storage part 7 Voltage measurement part 8 Current measurement part 9 Temperature measurement part 10 Secondary battery 11 Single battery 12 Battery case 13 Temperature sensor 20 Vehicle ECU (vehicle control device)
21 Engine ECU (Engine control device)
22 Power unit 23 Generator 24 Engine 25 Transmission 26 Motor 27 Reduction gear 28 Front wheel 29 Rear wheel 30 Drive shaft 31 Shaft

Claims (12)

A battery control device for controlling input / output of a secondary battery,
A first SOC calculation unit, a second SOC calculation unit, and a determination unit;
The first SOC calculation unit calculates a first estimated SOC of the secondary battery by accumulating currents during charging and discharging of the secondary battery.
The second SOC calculation unit calculates a second estimated SOC of the secondary battery based on a charge / discharge history of the secondary battery,
The determination unit compares the first estimated SOC with the second estimated SOC, and when the difference is larger than a reference value, the determination unit performs the secondary battery with respect to the device using the secondary battery. A battery control device that instructs the use of the secondary battery to increase the fluctuation range of the SOC of the battery.   The determination unit further determines whether the charge / discharge history is initialized, and increases the SOC fluctuation range of the secondary battery for the device even when the charge / discharge history is initialized. The battery control device according to claim 1, wherein the battery control device instructs use of the secondary battery. A battery control device for controlling input / output of a secondary battery,
A determination unit, wherein the determination unit determines whether the charge / discharge history used for calculating the SOC of the secondary battery has been initialized, and when the charge / discharge history is initialized, the secondary battery A battery control device that instructs a device using the secondary battery to increase the SOC fluctuation range of the secondary battery. An electric vehicle including a motor as a power source,
A secondary battery, a battery control device that controls input / output of the secondary battery, and a vehicle control device that controls driving of the motor;
The battery control device includes a first SOC calculation unit, a second SOC calculation unit, and a determination unit,
The first SOC calculation unit calculates a first estimated SOC of the secondary battery by accumulating currents during charging and discharging of the secondary battery.
The second SOC calculation unit calculates a second estimated SOC of the secondary battery based on a charge / discharge history of the secondary battery,
The determination unit compares the first estimated SOC with the second estimated SOC, and outputs a signal to the vehicle control device when the difference is larger than a reference value.
The vehicle control device drives the motor so that the fluctuation range of the SOC of the secondary battery increases when the determination unit outputs the signal.   The electric motor according to claim 4, wherein the determination unit determines whether the charge / discharge history is initialized, and outputs a signal to the vehicle control device even when the charge / discharge history is initialized. vehicle. An electric vehicle including a motor as a power source,
A secondary battery, a battery control device that controls input / output of the secondary battery, and a vehicle control device that controls driving of the motor;
The battery control device includes a determination unit, and the determination unit determines whether the charge / discharge history used for calculating the SOC of the secondary battery is initialized, and the charge / discharge history is initialized. A signal is output to the vehicle control device,
The vehicle control device drives the motor so that the fluctuation range of the SOC of the secondary battery increases when the determination unit outputs the signal. A control method for controlling input / output of a secondary battery,
(A) integrating the current during charging / discharging of the secondary battery to calculate a first estimated SOC of the secondary battery;
(B) calculating a second estimated SOC of the secondary battery based on the charge / discharge history of the secondary battery;
(C) comparing the first estimated SOC and the second estimated SOC;
(D) As a result of comparison in the step (c), when these differences are larger than a reference value, the variation range of the SOC of the secondary battery is increased with respect to a device using the secondary battery. And a secondary battery control method comprising: a step of instructing use of the secondary battery.   It is determined whether the charge / discharge history is initialized, and when the charge / discharge history is initialized, the secondary battery is used to increase the SOC fluctuation range of the secondary battery when the charge / discharge history is initialized. The method for controlling a secondary battery according to claim 7, further comprising an instruction step. A control method for controlling input / output of a secondary battery,
(A) determining whether the charge / discharge history used for calculating the SOC of the secondary battery has been initialized;
(B) When the charging / discharging history is initialized as a result of the determination in the step (a), the fluctuation range of the SOC of the secondary battery is increased with respect to the device using the secondary battery. And a step of instructing the use of the secondary battery. A program for causing a computer to execute input / output control of a secondary battery,
The program is
(A) integrating the current during charging / discharging of the secondary battery to calculate a first estimated SOC of the secondary battery;
(B) calculating a second estimated SOC of the secondary battery based on the charge / discharge history of the secondary battery;
(C) comparing the first estimated SOC with the second estimated SOC;
(D) As a result of the comparison in the step (c), when these differences are larger than a reference value, the variation range of the SOC of the secondary battery is increased with respect to the device using the secondary battery. A program for causing a computer to execute a step of instructing use of a secondary battery.   It is determined whether the charge / discharge history is initialized, and when the charge / discharge history is initialized, the secondary battery is used to increase the SOC fluctuation range of the secondary battery when the charge / discharge history is initialized. The program according to claim 10, further comprising a step of indicating. A program for causing a computer to execute input / output control of a secondary battery,
The program is
(A) determining whether the charge / discharge history used for calculating the SOC of the secondary battery has been initialized;
(B) When the charging / discharging history is initialized as a result of the determination in the step (a), the fluctuation range of the SOC of the secondary battery is increased with respect to the device using the secondary battery. A program causing a computer to execute the step of instructing use of the secondary battery.

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