JP6672976B2 - Charge amount calculation device, computer program, and charge amount calculation method - Google Patents

Description

  The present invention relates to a charge amount calculation device for calculating a charge amount of a secondary battery, a computer program for realizing the charge amount calculation device, and a charge amount calculation method.

  In recent years, vehicles such as HEVs (Hybrid Electric Vehicles) and EVs (Electric Vehicles) have become widespread. HEV and EV are equipped with a secondary battery. In such a vehicle, switching between charging and discharging of the secondary battery is repeated as the vehicle travels. Since the state of charge of the secondary battery greatly changes due to charging and discharging while the vehicle is running, it is necessary to accurately determine the state of charge (SOC) of the secondary battery.

  As a method of calculating the charge amount of the secondary battery, for example, a charge / discharge current of the secondary battery is detected, a current integrated value is calculated, and a first charge amount is calculated based on the calculated current integrated value. Then, the second charge amount is calculated based on the voltage of the secondary battery at the time of no load, and the second charge amount is calculated when the difference between the first charge amount and the second charge amount becomes a predetermined value or more. A charge amount calculation method for correcting the first charge amount based on the amount is disclosed (see Patent Document 1).

JP 2000-150003 A

  In the method of Patent Document 1, it is necessary to detect the voltage of the secondary battery at no load. Conditions for detecting the voltage of the secondary battery at no load include, for example, stopping the vehicle, turning off the ignition (IG), or forcibly stopping the charging and discharging of the secondary battery. There must be. For this reason, when the ignition (IG) is continuously turned on for a long time, the voltage of the secondary battery under no load cannot be detected. Also, if the charging and discharging of the secondary battery is forcibly stopped, the motor may not be driven by discharging from the secondary battery, or the secondary battery may be charged using regenerative power from the motor. In some cases, energy loss and regenerative braking force loss may occur.

  The present invention has been made in view of such circumstances, and a charge amount calculation device capable of accurately calculating the charge amount of a secondary battery even when a charge / discharge current flows through the secondary battery, It is an object of the present invention to provide a computer program and a charged amount calculating method for realizing an amount calculating device.

A charge amount calculation device according to an embodiment of the present invention is a charge amount calculation device that calculates a charge amount of a secondary battery, a voltage acquisition unit that obtains a voltage of the secondary battery, and a current of the secondary battery. A current acquisition unit that acquires the current, a first calculation unit that integrates the current acquired by the current acquisition unit to calculate a first charge amount of the secondary battery, a voltage acquired by the voltage acquisition unit, A second calculation unit that calculates a second charge amount of the secondary battery based on the current obtained by the unit and an equivalent circuit model of the secondary battery, and a determination unit that determines whether a predetermined condition is satisfied. When the determination unit determines that the predetermined condition is not satisfied, the first charge amount is set as the charge amount of the secondary battery, and when the determination unit determines that the predetermined condition is satisfied, the second charge is performed. the amount and the charge amount of the secondary battery, further, calculated by the second calculating section A charge amount difference calculation unit that calculates a charge amount difference between the first charge amount and the second charge amount calculated by the first calculation unit when the second charge amount is set as the charge amount of the secondary battery; A unit time error amount calculation unit that calculates a unit time error amount per unit time of the charge amount based on the charge amount difference calculated by the charge amount difference calculation unit, wherein the determination unit includes the second calculation unit in the basis of the second amount of charge calculated elapsed time and the unit time error amount from the time the charge amount of the of the secondary battery, determining whether to satisfy the predetermined condition.

A computer program according to an embodiment of the present invention causes a computer, a computer program for calculating the amount of charge of the secondary battery, the computer, and a voltage acquiring unit that acquires a voltage of the secondary battery, the two A current acquisition unit that acquires the current of the secondary battery, a first calculation unit that integrates the acquired current to calculate a first charge amount of the secondary battery, an acquired voltage, a current, and an equivalent circuit of the secondary battery. a second calculation unit for calculating a second amount of charge of the secondary battery based on the model, to function as a determination section for determining whether or not to satisfy the predetermined condition, determines not to satisfy the predetermined condition If the first charge amount and the charge amount of the secondary battery, when it is determined to satisfy the predetermined condition, to process the second charge amount as the charged amount of the secondary battery, further, the computer, calculates The first At the time when the charge amount is the charge amount of the secondary battery, a charge amount difference calculation unit that calculates a charge amount difference between the calculated first charge amount and the second charge amount, based on the calculated charge amount difference, A unit time error amount calculation unit that calculates a unit time error amount per unit time of the charge amount, and the elapsed time from the time when the calculated second charge amount is set as the charge amount of the secondary battery and the unit time error based on the amount, it determines whether to satisfy the predetermined condition.

A charge amount calculation method according to an embodiment of the present invention is a charge amount calculation method of calculating a charge amount of a secondary battery, wherein a voltage of the secondary battery is acquired by a voltage acquisition unit, and a current of the secondary battery is calculated. Is acquired by the current acquisition unit, the acquired current is integrated, the first charge amount of the secondary battery is calculated by the first calculation unit, and the acquired voltage and current and the equivalent circuit model of the secondary battery are calculated. The second calculating unit calculates a second charge amount of the secondary battery based on the first condition, and a determining unit determines whether a predetermined condition is satisfied. If it is determined that the predetermined condition is not satisfied, the first calculating unit determines whether the first condition is satisfied. The charge amount is the charge amount of the secondary battery, and if it is determined that the predetermined condition is satisfied, the second charge amount is the charge amount of the secondary battery, and the calculated second charge amount is the charge amount of the secondary battery. At the time when the charge amount of the next battery is set, the calculated first charge amount and the second charge amount are charged. The charge amount difference calculation unit calculates the difference, and the unit time error amount calculation unit calculates the unit time error amount per unit time of the charge amount based on the calculated charge amount difference, and the calculated second charge amount the based on the elapsed time and the unit time error amount from the time the charge amount of the of the secondary battery, determining whether to satisfy the predetermined condition.

  According to the present invention, it is possible to accurately calculate the charge amount of a secondary battery even when a charge / discharge current is flowing through the secondary battery.

1 is a block diagram illustrating an example of a configuration of a main part of a vehicle equipped with a battery monitoring device as a charge amount calculation device according to the present embodiment. It is a block diagram showing an example of composition of a battery monitoring device of this embodiment. FIG. 4 is an explanatory diagram illustrating an example of an equivalent circuit model of the secondary battery unit according to the present embodiment. FIG. 5 is a schematic diagram showing an example of a change in voltage after the charging of the secondary battery unit 50 according to the present embodiment is started. FIG. 5 is a schematic diagram illustrating an example of a transition of a voltage after the secondary battery unit 50 according to the present embodiment starts discharging. FIG. 5 is an explanatory diagram illustrating an example of a correlation between an open circuit voltage and a charged amount of the secondary battery unit according to the present embodiment. It is a schematic diagram which shows the principal part of the calculation process of the charge amount of a secondary battery unit by the battery monitoring apparatus of this Embodiment. FIG. 4 is an explanatory diagram illustrating an example of a current waveform of the secondary battery unit according to the present embodiment. It is an explanatory view showing an example of each charge amount calculated by the battery monitoring device of the present embodiment. It is an explanatory view showing an example of the amount of charge of the secondary battery unit by the battery monitoring device of the present embodiment. FIG. 5 is an explanatory diagram illustrating an example of an error in a charged amount of a secondary battery unit by the battery monitoring device according to the present embodiment. 5 is a flowchart illustrating a first example of a processing procedure for calculating a charged amount by the battery monitoring device according to the present embodiment. 5 is a flowchart illustrating an example of a processing procedure of calculating a battery equivalent circuit model SOC by the battery monitoring device according to the present embodiment. 5 is a flowchart illustrating an example of a processing procedure of calculating a battery equivalent circuit model SOC by the battery monitoring device according to the present embodiment. 9 is a flowchart illustrating a second example of a processing procedure for calculating a charged amount by the battery monitoring device according to the present embodiment. 9 is a flowchart illustrating a third example of a processing procedure for calculating a charged amount by the battery monitoring device according to the present embodiment. 11 is a flowchart illustrating a fourth example of a processing procedure for calculating a charged amount by the battery monitoring device according to the present embodiment.

[Description of Embodiment of the Present Invention]
A charge amount calculation device according to an embodiment of the present invention is a charge amount calculation device that calculates a charge amount of a secondary battery, a voltage acquisition unit that obtains a voltage of the secondary battery, and a current of the secondary battery. A current acquisition unit that acquires the current, a first calculation unit that integrates the current acquired by the current acquisition unit to calculate a first charge amount of the secondary battery, a voltage acquired by the voltage acquisition unit, A second calculation unit that calculates a second charge amount of the secondary battery based on the current obtained by the unit and an equivalent circuit model of the secondary battery, and a determination unit that determines whether a predetermined condition is satisfied. When the determination unit determines that the predetermined condition is not satisfied, the first charge amount is set as the charge amount of the secondary battery, and when the determination unit determines that the predetermined condition is satisfied, the second charge is performed. The amount is defined as the charge amount of the secondary battery.

  A computer program according to an embodiment of the present invention is a computer program for causing a computer to calculate a charge amount of a secondary battery, the computer program comprising: a voltage acquisition unit that acquires a voltage of a secondary battery; A current acquisition unit that acquires the current of the secondary battery, a first calculation unit that integrates the acquired current to calculate a first charge amount of the secondary battery, an acquired voltage, a current, and an equivalent circuit of the secondary battery. A second calculation unit that calculates a second charge amount of the secondary battery based on a model, and a function as a determination unit that determines whether a predetermined condition is satisfied. If it is determined that the predetermined condition is not satisfied, The first charge amount is set as the charge amount of the secondary battery, and when it is determined that the predetermined condition is satisfied, the second charge amount is processed as the charge amount of the secondary battery.

  A charge amount calculation method according to an embodiment of the present invention is a charge amount calculation method of calculating a charge amount of a secondary battery, wherein a voltage of the secondary battery is acquired by a voltage acquisition unit, and a current of the secondary battery is calculated. Is acquired by the current acquisition unit, the acquired current is integrated, the first charge amount of the secondary battery is calculated by the first calculation unit, and the acquired voltage and current and the equivalent circuit model of the secondary battery are calculated. The second calculating unit calculates a second charge amount of the secondary battery based on the first condition, and a determining unit determines whether a predetermined condition is satisfied. If it is determined that the predetermined condition is not satisfied, the first calculating unit determines whether the first condition is satisfied. The charge amount is the charge amount of the secondary battery, and if it is determined that the predetermined condition is satisfied, the second charge amount is the charge amount of the secondary battery.

  The voltage acquisition unit acquires the voltage of the secondary battery, and the current acquisition unit acquires the current (including the charging current and the discharging current) of the secondary battery. The first calculation unit calculates a first charge amount of the secondary battery by integrating the currents obtained by the current obtaining unit. The first charge amount is a charge amount based on current integration. The current integration is obtained by integrating the current with time. For example, if the sampling interval of the current acquisition is Δt and the acquired current value is Ibi (i = 1, 2,...) At each sampling, the current integration is , ΣIbi × Δt (i = 1, 2,...). Assuming that the most recently obtained charge amount is SOCin and the first charge amount is SOC1, the first charge amount is expressed by the following formula: SOC1 = SOCin ± {Ibi × Δt (i = 1, 2,...) / Full charge capacity FCC}. Can be calculated. In this formula, the sign ± uses + during charging and − during discharging.

  The second calculation unit calculates a second charge amount of the secondary battery based on the voltage acquired by the voltage acquisition unit, the current acquired by the current acquisition unit, and an equivalent circuit model of the secondary battery. The second charge amount is a charge amount based on an equivalent circuit model of the secondary battery. Since the second charge amount does not employ current integration, the second charge amount is not affected by a current value error that gradually increases in the process of integrating current. The equivalent circuit model is an equivalent circuit representing the impedance of the secondary battery, and can be represented by, for example, an impedance constituted by a combination of a voltage source having an open circuit voltage OCV, a resistor, and a parallel circuit of a resistor and a capacitor. The voltage and the current are values when the secondary battery is charging or discharging, and the secondary battery is not in a no-load state.

  The determining unit determines whether a predetermined condition is satisfied. The predetermined condition may be, for example, a condition indicating whether or not an error in current integration exceeds an allowable range. That is, when the error of the current integration exceeds the allowable range, it can be determined that the predetermined condition is satisfied. When the error does not exceed the allowable range, it can be determined that the predetermined condition is not satisfied.

  When the determination unit determines that the predetermined condition is not satisfied (when the current integration error does not exceed the allowable range), the first charge amount is the charge amount of the secondary battery, and the determination unit determines that the predetermined condition is satisfied. When the error of the current integration exceeds the allowable range, the second charge is used as the charge of the secondary battery in order to correct the first charge (replace the first charge with the second charge). Thereby, when the error of the current integration is within the allowable range, the first charge amount based on the current integration is set as the charged amount, and when the error of the current integration exceeds the allowable range, the first integrated charge is not affected by the current integration. The second charge amount based on the equivalent circuit model can be used as the charge amount, and the charge amount of the secondary battery can be accurately calculated even when a charge / discharge current flows through the secondary battery.

  In the charge amount calculation device according to the embodiment of the present invention, the determination unit determines that the predetermined condition is not satisfied when the time for integrating the current of the secondary battery is shorter than a predetermined integration time.

  The determination unit determines that the predetermined condition is not satisfied when the time for integrating the current of the secondary battery is less than the predetermined integration time. The predetermined integration time is such that when the current of the secondary battery is detected by the current sensor at a predetermined sampling period and the current integration is performed, the error of the obtained current value, that is, the error of the current integration is accumulated and the allowable range is accumulated. It can be a time considered to exceed. Further, the starting point of the predetermined integrated time is, for example, the time when the power supply of the secondary battery is started, or the most recent (previous) correction time when the first charge amount is corrected by replacing the first charge amount with the second charge amount. It can be.

  According to the above configuration, when the error of the current integration does not exceed the allowable range, the first charge amount based on the current integration that is more accurate than the accuracy of the second charge amount based on the equivalent circuit model can be used. Therefore, the charge amount of the secondary battery can be accurately calculated.

  The charge amount calculation device according to the embodiment of the present invention includes a switching determination unit that determines whether to switch the charging and discharging of the secondary battery based on the current acquired by the current acquisition unit, the determination unit includes: When the time for integrating the current of the secondary battery is equal to or longer than the integration time, it is determined whether or not the predetermined condition is satisfied according to the presence or absence of switching determined by the switching determination unit.

  The switching determination unit determines whether to switch charging and discharging of the secondary battery based on the current acquired by the current acquisition unit. For example, one of charge and discharge is defined as positive, and when the current changes from positive to negative, or when the current changes from negative to positive, it is possible to determine that there is switching between charging and discharging.

  When the time for integrating the current of the secondary battery is equal to or longer than the integration time, the determination unit determines whether or not a predetermined condition is satisfied, depending on whether or not the switching of the charging and discharging determined by the switching determination unit is performed. For example, when the switching determination unit determines that the switching between the charging and discharging has been performed, it can be determined that the predetermined condition is satisfied.

  When switching from charging to discharging or from discharging to charging, it is considered that the internal impedance of the secondary battery is reset once, and the accuracy of the equivalent circuit model increases. Therefore, when the error of the current integration exceeds the allowable range and there is switching between charging and discharging of the secondary battery, an equivalent circuit model having a higher accuracy than the accuracy of the first charge amount based on the current integration is obtained. Since the second charge amount based on the second charge amount can be used, the charge amount of the secondary battery can be accurately calculated.

  In the charge amount calculation device according to the embodiment of the present invention, the second calculation unit may be configured such that, when the switching determination unit determines that there is a charge / discharge switch, the second calculator calculates the voltage after a lapse of a predetermined time from the charge / discharge switch time. A second charge amount of the secondary battery is calculated based on the voltage acquired by the acquisition unit and the current acquired by the current acquisition unit.

  The second calculation unit, when the switching determination unit determines that there is a charge / discharge switch, based on the voltage acquired by the voltage acquisition unit and the current acquired by the current acquisition unit after a lapse of a predetermined time from the charge / discharge switch time. A second charge amount of the secondary battery is calculated. Since the impedance of the secondary battery is stabilized in accordance with the energization time after switching between charging and discharging, and the influence of overvoltage can be reduced, the accuracy of the second charge amount based on the equivalent circuit model can be increased.

  The charge amount calculation device according to the embodiment of the present invention may be configured such that the first charge amount calculated by the first calculation unit at the time when the second charge amount calculated by the second calculation unit is set as the charge amount of the secondary battery. A charge amount difference calculator for calculating a charge amount difference between the charge amount and the second charge amount, and calculating a unit time error amount per unit time of the charge amount based on the charge amount difference calculated by the charge amount difference calculator. A unit time error amount calculation unit that performs the calculation, wherein the determination unit calculates the unit time error amount and the elapsed time from the time when the second charge amount calculated by the second calculation unit is set as the charge amount of the secondary battery. Then, it is determined whether or not the predetermined condition is satisfied.

  The charge amount difference calculation unit corrects the first charge amount by replacing the second charge amount calculated by the second calculation unit with the charge amount of the secondary battery (that is, replacing the first charge amount with the second charge amount). At the correction point in time), a charge amount difference between the first charge amount and the second charge amount calculated by the first calculation unit is calculated. Assuming that the first charge amount is SOC1 and the second charge amount is SOC2, the charge amount difference ΔSOC can be represented by the following equation: ΔSOC = SOC2-SOC1.

  The unit time error amount calculation unit calculates a unit time error amount per unit time of the charge amount based on the charge amount difference calculated by the charge amount difference calculation unit. Assuming that the unit time error amount is ΔEt and the time required for charging or discharging the capacity ΔEAh corresponding to the charge amount difference ΔSOC is Te, it can be calculated by the equation ΔEt = ΔEAh / Te. Here, when the full charge capacity of the secondary battery is FCC, ΔEAh = FCC × ΔSOC / 100. That is, the capacity ΔEAh is obtained by converting the charge amount difference ΔSOC whose unit is% into Ah unit.

  The determination unit is configured to determine a predetermined amount based on the elapsed time and the unit time error amount from the time when the second charge amount calculated by the second calculation unit is set as the charge amount of the secondary battery (that is, the latest correction time of the charge amount). It is determined whether the condition is satisfied. For example, when the unit time error amount ΔEt × elapsed time t is equal to or more than a predetermined value, it is determined that the error amount (ΔEt × t) is equal to or more than a predetermined value, and it is determined that the predetermined condition is satisfied. Accordingly, it is possible to determine whether to correct the first charge amount by replacing the first charge amount with the second charge amount based on the charge amount difference ΔSOC obtained most recently.

  The charge amount calculation device according to the embodiment of the present invention may be configured such that the first charge amount calculated by the first calculation unit at the time when the second charge amount calculated by the second calculation unit is set as the charge amount of the secondary battery. A charge amount difference calculator for calculating a charge amount difference between the charge amount and the second charge amount, and calculating a unit capacity error amount per unit capacity of the charge amount based on the charge amount difference calculated by the charge amount difference calculator. And a unit capacity error amount calculation unit that performs the charge and discharge capacity of the secondary battery after the time when the second charge amount calculated by the second calculation unit is set as the charge amount of the secondary battery. It is determined whether or not the predetermined condition is satisfied based on the unit capacitance error amount.

  The charge amount difference calculation unit corrects the first charge amount by replacing the second charge amount calculated by the second calculation unit with the charge amount of the secondary battery (that is, replacing the first charge amount with the second charge amount). At the correction point in time), a charge amount difference between the first charge amount and the second charge amount calculated by the first calculation unit is calculated. Assuming that the first charge amount is SOC1 and the second charge amount is SOC2, the charge amount difference ΔSOC can be represented by the following equation: ΔSOC = SOC2-SOC1.

  The unit capacity error amount calculation unit calculates a unit capacity error amount per unit capacity of the charge amount based on the charge amount difference calculated by the charge amount difference calculation unit. Assuming that the unit capacity error amount is ΔEc and the charging / discharging capacity absolute value that reaches the capacity ΔEAh corresponding to the charge amount difference ΔSOC is Ca, it can be calculated by the equation ΔEc = ΔEAh / Ce. Here, when the full charge capacity of the secondary battery is FCC, ΔEAh = FCC × ΔSOC / 100. That is, the capacity ΔEAh is obtained by converting the charge amount difference ΔSOC whose unit is% into Ah unit.

  The determination unit determines the charge / discharge capacity and the unit capacity error amount of the secondary battery after the time when the second charge amount calculated by the second calculation unit is set as the charge amount of the secondary battery (that is, the latest correction time of the charge amount). It is determined whether or not a predetermined condition is satisfied based on. For example, when the unit capacity error amount ΔEc × the charge / discharge capacity c (the absolute value of the charge / discharge capacity after the latest correction of the charge amount) is equal to or more than a predetermined value, the error amount (ΔEc × c) is equal to or more than the predetermined value. , It can be determined that the predetermined condition is satisfied. Accordingly, it is possible to determine whether to correct the first charge amount by replacing the first charge amount with the second charge amount based on the charge amount difference ΔSOC obtained most recently.

  The charge amount calculation device according to the embodiment of the present invention includes a voltage acquired by the voltage acquisition unit, a current acquired by the current acquisition unit, and an open circuit voltage of the secondary battery based on an equivalent circuit model of the secondary battery. The open-circuit voltage calculating section for calculating the open-circuit voltage and the open-circuit voltage calculated by the open-circuit voltage calculating section and the correspondence between the open-circuit voltage of the secondary battery and the charge amount. Is calculated.

  The open-circuit voltage calculating unit calculates the open-circuit voltage OCV of the secondary battery based on the voltage Vb obtained by the voltage obtaining unit, the current Ib obtained by the current obtaining unit, and the equivalent circuit model of the secondary battery. For example, between an overvoltage generated by a current Ib flowing through an equivalent circuit model (impedance expressed by the equivalent circuit model), a voltage Vb acquired (detected), and an open circuit voltage OCV, (OCV = Vb−overvoltage) The relationship holds. Here, if the current Ib is positive during charging and negative during discharging, the overvoltage is also positive during charging and negative during discharging.

  The second calculation unit calculates the second charge amount of the secondary battery based on the open circuit voltage OCV calculated by the open circuit voltage calculation unit and the correspondence between the open circuit voltage of the secondary battery and the charge amount. The correspondence between the open-circuit voltage OCV of the secondary battery and the state of charge SOC may be stored in the storage unit in advance, or the correspondence may be calculated by an arithmetic circuit. Accordingly, it is not necessary to detect the voltage of the secondary battery at the time of no load, and even when the charge / discharge current is flowing through the secondary battery, the second charge amount for correcting the first charge amount based on the current integration Can be calculated.

[Details of the embodiment of the present invention]
Hereinafter, a description will be given based on the drawings showing an embodiment of a charge amount calculation device according to the present invention. FIG. 1 is a block diagram illustrating an example of a configuration of a main part of a vehicle equipped with a battery monitoring device 100 as a charge amount calculation device according to the present embodiment. As shown in FIG. 1, in addition to the battery monitoring device 100, the vehicle includes a secondary battery unit 50, relays 61 and 63, a generator (ALT) 62, a starter motor (ST) 64, a battery 65, an electric load 66, and the like. Is provided.

  The secondary battery unit 50 is, for example, a lithium ion battery, and has a plurality of cells 51 connected in series or series / parallel. The secondary battery unit 50 includes a voltage sensor 52, a current sensor 53, and a temperature sensor 54. The voltage sensor 52 detects the voltage of each cell 51 and the voltage at both ends of the secondary battery unit 50, and outputs the detected voltage to the battery monitoring device 100 via the voltage detection line 50a. The current sensor 53 includes, for example, a shunt resistor or a Hall sensor, and detects a charging current and a discharging current of the secondary battery unit 50. The current sensor 53 outputs the current detected via the current detection line 50b to the battery monitoring device 100. The temperature sensor 54 includes, for example, a thermistor, and detects the temperature of the cell 51. Temperature sensor 54 outputs the temperature detected via temperature detection line 50c to battery monitoring device 100.

  The battery 65 is, for example, a lead battery, and supplies power to the electric load 66 of the vehicle, and supplies power for driving the starter motor 64 when the relay 63 is turned on. The generator 62 generates power by the rotation of the engine of the vehicle, and outputs a direct current by a rectification circuit provided therein to charge the battery 65. In addition, when the relay 61 is turned on, the generator 62 charges the battery 65 and the secondary battery unit 50. The ON / OFF of the relays 61 and 63 is performed by a relay control unit (not shown).

  FIG. 2 is a block diagram illustrating an example of a configuration of the battery monitoring device 100 according to the present embodiment. The battery monitoring device 100 includes a control unit 10 that controls the entire device, a voltage acquisition unit 11, a current acquisition unit 12, a first charge amount calculation unit 13, a second charge amount calculation unit 14, an open voltage calculation unit 15, a condition determination unit. 16, a switching determination unit 17, a charge amount difference calculation unit 18, a unit time error amount calculation unit 19, a unit capacity error amount calculation unit 20, a storage unit 21, a timer 22 for clocking, and the like.

  The voltage acquisition unit 11 acquires a voltage of the secondary battery unit 50 (for example, a voltage across the secondary battery unit 50). Further, the current acquisition unit 12 acquires the current (charge current and discharge current) of the secondary battery unit 50. The acquisition frequency of the voltage and the current and the sampling period to be acquired can be controlled by the control unit 10. The sampling period can be, for example, 10 ms, but is not limited to this.

  The first charge amount calculation unit 13 has a function as a first calculation unit, and calculates the first charge amount of the secondary battery unit 50 by integrating the currents acquired by the current acquisition unit 12. The first charge amount is a charge amount based on current integration, and is also referred to as current integration SOC. In the present embodiment, the charge amount is also referred to as SOC (State Of Charge) or charge rate, and represents the ratio of the charged capacity to the full charge capacity. The current integration is obtained by integrating the current with time. For example, if the sampling interval of the current acquisition is Δt and the acquired current value is Ibi (i = 1, 2,...) At each sampling, the current integration is , ΣIbi × Δt (i = 1, 2,...). Assuming that the most recently obtained charge amount is SOCin and the first charge amount is SOC1, the first charge amount is expressed by the following formula: SOC1 = SOCin ± {Ibi × Δt (i = 1, 2,...) / Full charge capacity FCC}. Can be calculated. In this formula, the sign ± uses + during charging and − during discharging.

  The second charge amount calculating unit 14 has a function as a second calculating unit, and is based on the voltage obtained by the voltage obtaining unit 11, the current obtained by the current obtaining unit 12, and the equivalent circuit model of the secondary battery unit 50. The second charge amount of the secondary battery unit 50 is calculated. The second charge amount is a charge amount based on an equivalent circuit model of the secondary battery unit 50, and is also referred to as a battery equivalent circuit model SOC. Since the second charge amount does not employ the current integration, the second charge amount is not affected by a current value error (for example, an error of the current sensor 53) that gradually increases and accumulates in the process of integrating the current. The voltage and current are values when the secondary battery unit 50 is charging or discharging, and the secondary battery unit 50 is not in a no-load state.

  FIG. 3 is an explanatory diagram illustrating an example of an equivalent circuit model of the secondary battery unit 50 according to the present embodiment. The equivalent circuit model (also referred to as a battery equivalent circuit model) is an equivalent circuit representing the impedance of the secondary battery unit 50. For example, as shown in FIG. 3, a voltage source having an open circuit voltage OCV, a resistor R1, a resistor and a capacitor (FIG. 3 shows a configuration in which four parallel circuits each including the resistors R2 to R5 and each of the capacitors C2 to C5 are connected in series in FIG. 3). The secondary battery unit 50 is determined by a voltage source having an open circuit voltage OCV, a series resistance of an internal impedance, and the like. The open circuit voltage OCV is determined by a static balance between the positive electrode, the negative electrode, and the electrolyte, and the internal impedance is determined by a dynamic mechanism.

  More specifically, the resistor R1 represents, for example, the resistance of the electrolyte bulk, the resistors R2 to R5 represent, for example, interface charge transfer resistance and diffusion impedance, and the capacitors C2 to C5 represent, for example, electric double layer capacitance. Represents The resistance of the electrolyte bulk includes the conduction resistance of lithium (Li) ions in the electrolyte and the electronic resistance of the positive electrode and the negative electrode. The interface charge transfer resistance includes a charge transfer resistance and a film resistance on the active material surface. The diffusion impedance is an impedance resulting from a diffusion process of lithium (Li) ions into the active material particles. Note that the equivalent circuit model of the secondary battery unit 50 is an example, and is not limited to the example of FIG.

  The condition determination unit 16 has a function as a determination unit, and determines whether a predetermined condition is satisfied. The predetermined condition can be, for example, a condition indicating whether or not the error of the current integration exceeds a predetermined allowable range. That is, when the error of the current integration exceeds the allowable range, it can be determined that the predetermined condition is satisfied. When the error does not exceed the allowable range, it can be determined that the predetermined condition is not satisfied.

  When the condition determination unit 16 determines that the predetermined condition is not satisfied (when the current integration error does not exceed the allowable range), the control unit 10 sets the first charge amount as the charge amount of the secondary battery unit 50. When the condition determining unit 16 determines that the predetermined condition is satisfied (when the error of the current integration exceeds the allowable range), the control unit 10 sets the second charged amount to the secondary battery in order to correct the first charged amount. The charge amount of the unit 50 is set (the first charge amount is replaced with the second charge amount). Note that correcting the first charge amount with the second charge amount is also referred to as current integrated SOC correction.

  According to the above configuration, when the error of the current integration is within the allowable range, the first charge amount based on the current integration is set as the charge amount, and when the error of the current integration exceeds the allowable range, the influence of the current integration is reduced. The second charge amount based on the equivalent circuit model that is not received can be used as the charge amount. Thereby, even when a charge / discharge current is flowing through the secondary battery unit 50, the charge amount of the secondary battery unit 50 can be accurately calculated.

  Next, the above-described predetermined condition will be described. The predetermined condition can be set based on, for example, the integration time of the current integration, the presence or absence of switching between charging and discharging of the secondary battery unit 50, and the like. First, the integration time of the current integration will be described.

  If the time for integrating the current of the secondary battery unit 50 is less than the predetermined integration time, the condition determination unit 16 determines that the predetermined condition is not satisfied. When the current sensor 53 detects the current of the secondary battery unit 50 at a predetermined sampling period and performs current integration, the predetermined integration time is an error in the obtained current value (detection error by the current sensor 53), The time can be considered as a time when the errors of the current integration are accumulated and exceed the allowable range. The integration time can be, for example, 10 minutes, 20 minutes, or the like, but is not limited to these values. Further, the starting point of the predetermined integration time is, for example, the time when the energization (charging or discharging) of the secondary battery unit 50 is started, or the latest (last time) in which the first charge amount is corrected and replaced with the second charge amount. At the time of correction.

  According to the above configuration, when the error of the current integration does not exceed the allowable range, the first charge amount based on the current integration that is more accurate than the accuracy of the second charge amount based on the equivalent circuit model can be used. Therefore, the charge amount of the secondary battery unit 50 can be accurately calculated.

  Next, a case where the predetermined condition is set based on whether or not the charging and discharging of the secondary battery unit 50 is switched will be described.

  The switching determination unit 17 determines whether to switch the charging and discharging of the secondary battery unit 50 based on the current acquired by the current acquisition unit 12. For example, one of charge and discharge is defined as positive, and when the current changes from positive to negative, or when the current changes from negative to positive, it is possible to determine that there is switching between charging and discharging.

  When the time for integrating the current of the secondary battery unit 50 is equal to or longer than the integration time, the condition determination unit 16 determines whether or not a predetermined condition is satisfied according to whether or not the switching between the charging and discharging determined by the switching determination unit 17 is performed. Is determined. For example, when the switching determination unit 17 determines that the charge / discharge has been switched, it can be determined that the predetermined condition is satisfied. In addition, when the switching determination unit 17 determines that there is no switching between charging and discharging, it can be determined that the predetermined condition is not satisfied.

  When switching from charging to discharging or from discharging to charging, it is considered that the internal impedance of the secondary battery unit 50 is reset once, and the accuracy of the equivalent circuit model is increased. Therefore, when the error of the current integration exceeds the allowable range and there is switching between charging and discharging of the secondary battery unit 50, an equivalent circuit with higher accuracy than the accuracy of the first charge amount based on the current integration. Since the second charge amount based on the model can be used, the charge amount of the secondary battery unit 50 can be accurately calculated.

  When the switching determination unit 17 determines that there is a charge / discharge switch, the second charge amount calculation unit 14 uses the voltage and current acquisition unit 12 acquired by the voltage acquisition unit 11 after a lapse of a predetermined time from the charge / discharge switch time. The second charge amount of the secondary battery unit 50 is calculated based on the obtained current. For the predetermined time, different values may be used for the case where switching from charging to discharging and the case for switching from discharging to charging, or the same value may be used. The predetermined time can be, for example, about 0.1 second to 2 seconds, but is not limited to these numerical values.

  The impedance of the secondary battery unit 50 is stabilized in accordance with the energizing time (charging time or discharging time) after switching between charging and discharging, and the influence of overvoltage can be reduced. Accuracy can be increased. Note that the overvoltage refers to a difference between the voltage (terminal voltage) of the secondary battery unit 50 and the open circuit voltage OCV (also referred to as open circuit voltage).

  Next, a method of calculating the second charge amount will be described more specifically.

  The open-circuit voltage calculation unit 15 calculates the open-circuit voltage OCV of the secondary battery unit 50 based on the voltage Vb acquired by the voltage acquisition unit 11, the current Ib acquired by the current acquisition unit 12, and the equivalent circuit model of the secondary battery unit 50. I do.

  FIG. 4 is a schematic diagram illustrating an example of a change in voltage after the start of charging of the secondary battery unit 50 according to the present embodiment. The upper part of FIG. 4 schematically shows the current Ib of the secondary battery unit 50 after charging is started from a state where neither charging nor discharging is performed. The lower part of FIG. 4 schematically illustrates the relationship between the open voltage OCV, the terminal voltage Vb, and the overvoltage of the secondary battery unit 50 after the start of charging. The overvoltage refers to the voltage of the difference between the voltage Vb of the secondary battery unit 50 and the open voltage OCV. The open-circuit voltage OCV indicates a static state of the terminal voltage of the secondary battery unit 50, and is an equilibrium when an external power supply is connected between the electrodes and the current is reduced to 0 A to relax for a long time within a time range in which self-discharge is not performed. Potential. As shown in FIG. 4, when the charging current Ib flows, the voltage Vb of the secondary battery unit 50 gradually increases due to various electrochemical reaction delays following the stepwise voltage increase. As shown in FIG. 4, the relationship (OCV = Vb-overvoltage) holds between the acquired (detected) voltage Vb, the overvoltage, and the open circuit voltage OCV. During charging, the current Ib is positive, and the overvoltage is also positive.

  FIG. 5 is a schematic diagram showing an example of a change in voltage after the secondary battery unit 50 according to the present embodiment starts discharging. The upper part of FIG. 5 schematically shows the current Ib of the secondary battery unit 50 after the discharge is started from a state where neither charging nor discharging is performed. The lower part of FIG. 5 schematically shows the relationship between the open voltage OCV, the terminal voltage Vb, and the overvoltage of the secondary battery unit 50 after the start of charging. As shown in FIG. 5, when the discharge current Ib flows, the voltage Vb of the secondary battery unit 50 gradually decreases due to the delay of various electrochemical reactions following the stepwise voltage drop. The relationship of OCV = Vb-overvoltage holds between the acquired (detected) voltage Vb, overvoltage, and open circuit voltage OCV. At the time of discharging, the current Ib is negative and the overvoltage is also negative, so that the relationship (OCV = Vb−overvoltage) can be expressed as (OCV = Vb + overvoltage) as shown in FIG.

  As described above, the relationship (OCV = Vb-overvoltage) holds between the overvoltage generated by the current Ib flowing through the equivalent circuit model, the acquired (detected) voltage Vb, and the open circuit voltage OCV. Here, if the current Ib is positive during charging and negative during discharging, the overvoltage is also positive during charging and negative during discharging.

  The second charge amount calculation unit 14 determines the second charge amount of the secondary battery unit 50 based on the open circuit voltage OCV calculated by the open circuit voltage calculation unit 15 and the correspondence between the open circuit voltage OCV of the secondary battery unit 50 and the charge amount SOC. 2 Calculate the charge amount.

  FIG. 6 is an explanatory diagram illustrating an example of a correlation between the open-circuit voltage and the charge amount of the secondary battery unit 50 according to the present embodiment. In FIG. 6, the horizontal axis indicates the open-circuit voltage OCV, and the vertical axis indicates the state of charge SOC. As shown in FIG. 6, the charging amount increases as the open-circuit voltage of the secondary battery unit 50 increases. Note that the correlation between the open-circuit voltage and the charge amount illustrated in FIG. 6 may be stored in the storage unit 21 or may be calculated by an arithmetic circuit.

  According to the above configuration, it is not necessary to detect the voltage of the secondary battery unit 50 at the time of no load, and the first charge amount based on the current integration is corrected even when the charge / discharge current is flowing through the secondary battery unit 50. The second charge amount can be calculated.

  FIG. 7 is a schematic diagram illustrating a main part of a process of calculating the charge amount of the secondary battery unit 50 by the battery monitoring device 100 according to the present embodiment. When the voltage Vb and the current Ib of the secondary battery unit 50 are acquired at a predetermined sampling period (for example, 10 ms), the first charge amount calculation unit 13 performs a current integration process and performs the current integration at the sampling period. A first charge amount is calculated. The control unit 10 outputs the calculated first charging capacity as the state of charge SOC of the secondary battery unit 50.

  The second charge amount calculator 14 calculates the overvoltage of the secondary battery unit 50 based on the current Ib of the secondary battery unit 50 and the battery equivalent circuit model, and subtracts the calculated overvoltage from the voltage Vb of the secondary battery unit 50. To calculate the open circuit voltage OCV. The second charge amount calculation unit 14 calculates the second charge amount by converting the calculated open circuit voltage OCV based on the OCV-SOC characteristic as illustrated in FIG. The calculation frequency of the second charge amount may be each time the above-described sampling cycle (for example, 10 ms) or every time a trigger described later is generated.

  The switching determination unit 17 performs a zero-crossing determination process (a determination process of the presence or absence of a current zero-cross, that is, a determination process of presence or absence of switching between charging and discharging) based on the current Ib of the secondary battery unit 50, and there is a current zero-crossing. A predetermined time lapse trigger generation process is performed in which a trigger (also referred to as a predetermined time lapse trigger) is generated at a point in time when a predetermined time (for example, about 0.1 second to 2 seconds or the like) has elapsed from the time point (charge / discharge switching time).

  The control unit 10 corrects the first charge amount by replacing the first charge amount with the second charge amount when the predetermined time lapse trigger is generated. That is, the control unit 10 outputs the second charge amount calculated by the second charge amount calculation unit 14 as the charge amount SOC of the secondary battery unit 50 when the predetermined time elapse trigger is generated.

  FIG. 8 is an explanatory diagram illustrating an example of a current waveform of the secondary battery unit 50 according to the present embodiment. In FIG. 8, the horizontal axis represents time, and the vertical axis represents current. When the current is positive, the battery is in a charged state, and when the current is negative, the battery is in a discharged state. In the example of FIG. 8, the transition of the current for about several hours is shown, and it can be seen that the current zero cross occurs at the timing of switching from charging to discharging and from discharging to charging. Note that the current waveform is an example, and the present invention is not limited to this.

  FIG. 9 is an explanatory diagram illustrating an example of each charge amount calculated by the battery monitoring device 100 according to the present embodiment. In FIG. 9, the horizontal axis indicates time, and the vertical axis indicates the state of charge SOC. In FIG. 9, a graph indicated by “current integration (with current error)” indicates a transition from the time 0 of the first charge amount calculated based on the current illustrated in FIG. 8. Further, the graph shown by the “battery equivalent circuit model” shows a transition from the time 0 of the second charge amount calculated based on the current illustrated in FIG. Further, a graph indicated by “current integration (without current error)” indicates a transition from time 0 when the currents illustrated in FIG. 8 are integrated without error, and represents a true value of current integration.

  As can be seen from FIG. 9, the deviation of the first charge amount based on the current integration from the true value of the current integration increases with time, and the error gradually increases. In addition, during a short time lapse from time 0, the difference between the first charge amount based on the current integration and the true value of the current integration is small, and the first charge amount accurately represents the charge amount of the secondary battery unit 50. You can see that it is. Also, it can be understood that the second charge amount tends to approach the true value of the current integration at the timing when the switching between the charge and the discharge occurs.

  FIG. 10 is an explanatory diagram illustrating an example of a charged amount of the secondary battery unit 50 by the battery monitoring device 100 according to the present embodiment. In FIG. 10, the horizontal axis indicates time, and the vertical axis indicates the state of charge SOC. In FIG. 10, the predetermined time elapse trigger is generated four times. It can be seen that the charge amount of the secondary battery unit 50 is corrected at the timing when the predetermined time lapse trigger is generated, as indicated by reference numerals A, B, C, and D in the figure.

  FIG. 11 is an explanatory diagram illustrating an example of an error in the amount of charge of the secondary battery unit 50 by the battery monitoring device 100 according to the present embodiment. In FIG. 11, the horizontal axis represents time, and the vertical axis represents an error in the state of charge SOC. In FIG. 11, the true value of the current integration is represented by a horizontal axis with an error of 0%. The graph indicated by “error before correction” indicates the ratio (error) of the difference between the first charge amount and the true value of current integration with respect to the true value of current integration. Further, a graph indicated by “error after correction” indicates a ratio (error) of the charged amount after correction to the true value of the current integration. As shown in FIG. 11, it can be seen that the charge amount of the secondary battery unit 50 is corrected at the timing when the predetermined time lapse trigger is generated so that the error is reduced.

  Next, the operation of the battery monitoring device 100 according to the present embodiment will be described. FIG. 12 is a flowchart illustrating a first example of a processing procedure for calculating the amount of charge by the battery monitoring device 100 according to the present embodiment. Hereinafter, for the sake of convenience, the subject of the processing will be described as the control unit 10. The control unit 10 calculates a current integrated SOC (first charge amount) (S11). The calculation frequency of the current integration SOC can be synchronized with the sampling cycle of the current detection of the secondary battery unit 50, and can be, for example, 10 ms. Details of the process of calculating the current integrated SOC will be described later.

  The control unit 10 determines whether the integration time T1 has elapsed from the start of energization (S12). The integration time T1 can be, for example, 10 minutes, 20 minutes, or the like. The integration time T1 may be set as appropriate according to the type and model of the secondary battery unit 50. When the integration time T1 has elapsed from the start of energization (YES in S12), the control unit 10 determines the presence or absence of a current zero cross (S13), and when there is a current zero cross (YES in S13), switches from charging to discharging. Is determined (S14).

  If the switching is from charging to discharging (YES in S14), the control unit 10 determines whether a predetermined time Tcd has elapsed from the time when the current zero cross occurred (S15). The predetermined time Tcd can be, for example, about 0.1 second to 2 seconds. If the predetermined time Tcd has not elapsed (NO in S15), the control unit 10 continues the processing in step S15. When the predetermined time Tcd has elapsed (YES in S15), the control unit 10 calculates a battery equivalent circuit model SOC (second charge amount) (S17). The details of the process of calculating the battery equivalent circuit model SOC will be described later.

  When switching from charging to discharging is not performed (NO in S14), that is, when switching from discharging to charging is performed, the control unit 10 determines whether or not a predetermined time Tdc has elapsed from the time when the current zero cross occurred. (S16). The predetermined time Tdc can be, for example, about 0.1 second to 2 seconds. If the predetermined time Tdc has not elapsed (NO in S16), the control unit 10 continues the processing in step S16. When predetermined time Tdc has elapsed (YES in S16), control unit 10 performs the process of step S17.

  The control unit 10 corrects the current integration SOC (S18). The correction of the current integrated SOC is a process of replacing the most recently calculated current integrated SOC with the battery equivalent circuit model SOC when a predetermined time Tcd or Tdc has elapsed.

  The control unit 10 resets the integrated time T1 (S19), outputs the replaced battery equivalent circuit model SOC as the state of charge SOC of the secondary battery unit 50 (S20), and ends the process. If the integration time T1 has not elapsed from the start of energization (NO in S12), or if there is no current zero crossing (NO in S13), the control unit 10 calculates the calculated current integration SOC as the charge amount of the secondary battery unit 50. It is output as SOC (S20), and the process ends. Note that the process illustrated in FIG. 12 can be repeatedly performed when charging or discharging of the secondary battery unit 50 continues.

  FIG. 13 is a flowchart illustrating an example of a processing procedure of current integrated SOC calculation by battery monitoring device 100 of the present embodiment. The control unit 10 acquires the current Ib of the secondary battery unit 50 at a predetermined sampling cycle (for example, 10 ms) (S101), and integrates the acquired current values (S102). The control unit 10 calculates the current integrated SOC by dividing the integrated current value by the full charge capacity (S103), and ends the processing. Note that the initial value of the SOC is, for example, the voltage obtained when the ignition is turned off or immediately after the ignition is turned on, that is, when the current of the secondary battery unit 50 is not flowing, is the OCV, and the SOC obtained from the OCV is the initial value. It should be a value.

  FIG. 14 is a flowchart illustrating an example of a processing procedure of calculating the battery equivalent circuit model SOC by the battery monitoring device 100 according to the present embodiment. The control unit 10 acquires the voltage Vb of the secondary battery unit 50 (S111), and acquires the current Ib (S112). The timing of acquiring the voltage Vb and the current Ib may be at a predetermined sampling cycle (for example, 10 ms) or after averaging values sampled a plurality of times.

  The control unit 10 calculates an overvoltage based on the obtained current Ib and the battery equivalent circuit model (S113), and calculates an open circuit voltage OCV based on the obtained voltage Vb and the calculated overvoltage (S114). The control unit 10 converts the calculated open circuit voltage OCV to calculate the battery equivalent circuit model SOC (S115), and ends the processing.

  FIG. 15 is a flowchart illustrating a second example of the processing procedure for calculating the charge amount by the battery monitoring device 100 according to the present embodiment. The difference from the first example shown in FIG. 12 is that the starting point of the integration time is different. The control unit 10 calculates a current integrated SOC (first charge amount) (S31). The calculation frequency of the current integration SOC can be synchronized with the sampling cycle of the current detection of the secondary battery unit 50, and can be, for example, 10 ms. The process of calculating the current integrated SOC is the same as the process shown in FIG.

  The control unit 10 determines whether or not the integration time T2 has elapsed from the previous (most recent) correction time point (S32). The integration time T2 can be, for example, 10 minutes, 20 minutes, or the like. The integration time T2 may be appropriately set according to the type and model of the secondary battery unit 50. When the integration time T2 has elapsed from the previous correction time point (YES in S32), the control unit 10 determines the presence or absence of a current zero cross (S33), and when there is a current zero cross (YES in S33), changes from charging to discharging. Is determined (S34).

  If the switching is from charging to discharging (YES in S34), the control unit 10 determines whether or not a predetermined time Tcd has elapsed from the time when the current zero cross occurred (S35). The predetermined time Tcd can be, for example, about 0.1 second to 2 seconds. If the predetermined time Tcd has not elapsed (NO in S35), the control unit 10 continues the process of step S35. When the predetermined time Tcd has elapsed (YES in S35), the control unit 10 calculates a battery equivalent circuit model SOC (second charge amount) (S37). The process of calculating the battery equivalent circuit model SOC is the same as the process shown in FIG.

  When switching from charging to discharging is not performed (NO in S34), that is, when switching from discharging to charging is performed, the control unit 10 determines whether or not a predetermined time Tdc has elapsed from the time when the current zero cross occurred. (S36). The predetermined time Tdc can be, for example, about 0.1 second to 2 seconds. If the predetermined time Tdc has not elapsed (NO in S36), the control unit 10 continues the process of step S36. When the predetermined time Tdc has elapsed (YES in S36), the control unit 10 performs the process of step S37.

  The control unit 10 corrects the current integrated SOC (S38). The correction of the current integrated SOC is a process of replacing the most recently calculated current integrated SOC with the battery equivalent circuit model SOC when a predetermined time Tcd or Tdc has elapsed.

  The control unit 10 resets the integrated time T2 (S39), outputs the replaced battery equivalent circuit model SOC as the state of charge SOC of the secondary battery unit 50 (S40), and ends the process. If the integration time T2 has not elapsed since the previous correction (NO in S32) or if there is no current zero crossing (NO in S33), the control unit 10 calculates the calculated current integration SOC of the secondary battery unit 50. The charge amount SOC is output (S40), and the process ends. Note that the process illustrated in FIG. 15 can be repeatedly performed when charging or discharging of the secondary battery unit 50 continues.

  Next, as to a method of calculating the state of charge SOC of the secondary battery unit 50 based on the correction amount (charge amount difference) of the previous (most recent) charge amount, a case where a unit time error amount is used as a third example, and Four cases will be described where the unit capacitance error amount is used. First, a case where a unit time error amount is used will be described as a third example.

  The charge amount difference calculation unit 18 determines when the second charge amount calculated by the second charge amount calculation unit 14 is used as the charge amount of the secondary battery unit 50 (that is, by replacing the first charge amount with the second charge amount). At the correction time when the first charge amount is corrected), the charge amount difference between the first charge amount calculated by the first charge amount calculation unit 13 and the replaced second charge amount is calculated. Assuming that the first charge amount is SOC1 and the second charge amount is SOC2, the charge amount difference ΔSOC can be represented by the following equation: ΔSOC = SOC2-SOC1.

  The unit time error amount calculation unit 19 calculates the unit time error amount per unit time of the charge amount based on the charge amount difference calculated by the charge amount difference calculation unit 18. Assuming that the unit time error amount is ΔEt and the time required for charging or discharging the capacity ΔEAh corresponding to the charge amount difference ΔSOC is Te, it can be calculated by the equation ΔEt = ΔEAh / Te. Here, assuming that the full charge capacity of the secondary battery unit 50 is FCC, ΔEAh = FCC × ΔSOC / 100. That is, the capacity ΔEAh is obtained by converting the charge amount difference ΔSOC whose unit is% into Ah unit.

  The condition determination unit 16 determines the elapsed time and the unit time from the time when the second charge amount calculated by the second charge amount calculation unit 14 is set as the charge amount of the secondary battery unit 50 (that is, the latest correction time of the charge amount). It is determined whether a predetermined condition is satisfied based on the error amount.

  For example, when the unit time error amount ΔEt × elapsed time t is equal to or more than a predetermined value, it is determined that the error amount (ΔEt × t) is equal to or more than a predetermined value, and it is determined that the predetermined condition is satisfied. Accordingly, it is possible to determine whether to correct the first charge amount by replacing the first charge amount with the second charge amount based on the charge amount difference ΔSOC obtained most recently.

  FIG. 16 is a flowchart illustrating a third example of the procedure for calculating the amount of charge by the battery monitoring device 100 according to the present embodiment. The control unit 10 calculates a current integrated SOC (first charge amount) (S51). The calculation frequency of the current integration SOC can be synchronized with the sampling cycle of the current detection of the secondary battery unit 50, and can be, for example, 10 ms. The process of calculating the current integrated SOC is the same as the process shown in FIG.

  The control unit 10 calculates an error amount per unit time (unit time error amount ΔEt) (S52), and determines whether the error amount (ΔEt × elapsed time t) is equal to or greater than a predetermined value (S53). The predetermined value can be about 5% to 10% of the SOC at the time of the determination, but is not limited to these values.

  When the error amount (ΔEt × elapsed time t) is equal to or greater than a predetermined value (YES in S53), the control unit 10 determines whether there is a current zero cross (S54), and when there is a current zero cross (YES in S54). Then, it is determined whether or not switching from charging to discharging is performed (S55).

  If the switching is from charging to discharging (YES in S55), the control unit 10 determines whether or not a predetermined time Tcd has elapsed from the time when the current zero cross occurred (S56). The predetermined time Tcd can be, for example, about 0.1 second to 2 seconds. If the predetermined time Tcd has not elapsed (NO in S56), the control unit 10 continues the process of step S56. When the predetermined time Tcd has elapsed (YES in S56), the control unit 10 calculates a battery equivalent circuit model SOC (second charge amount) (S57). The process of calculating the battery equivalent circuit model SOC is the same as the process shown in FIG.

  When switching from charging to discharging is not performed (NO in S55), that is, when switching from discharging to charging is performed, the control unit 10 determines whether or not a predetermined time Tdc has elapsed from the time when the current zero cross occurred. (S58). The predetermined time Tdc can be, for example, about 0.1 second to 2 seconds. When the predetermined time Tdc has not elapsed (NO in S58), the control unit 10 continues the process of step S58. When the predetermined time Tdc has elapsed (YES in S58), control unit 10 performs the process of step S57.

  The control unit 10 corrects the current integration SOC (S59). The correction of the current integrated SOC is a process of replacing the most recently calculated current integrated SOC with the battery equivalent circuit model SOC when a predetermined time Tcd or Tdc has elapsed.

  The control unit 10 outputs the replaced battery equivalent circuit model SOC as the state of charge SOC of the secondary battery unit 50 (S60), and ends the process. If the error amount (ΔEt × elapsed time t) is not equal to or greater than the predetermined value (NO in S53), or if there is no current zero cross (NO in S54), the control unit 10 calculates the calculated current integrated SOC by the secondary battery unit 50. (S60), and the process ends. Note that the process illustrated in FIG. 16 can be repeatedly performed when charging or discharging of the secondary battery unit 50 continues.

  In the processing illustrated in FIG. 16, the processing of steps S53, S54, S55, S56, and S58 may be omitted. That is, when the error amount (ΔEt × elapsed time t) is equal to or greater than the predetermined value (YES in S53), the control unit 10 calculates the battery equivalent circuit model SOC (second charge amount) (S57). Is also good.

  Next, a case where the unit capacitance error amount is used will be described as a fourth example.

  As in the case of the third example, the charge amount difference calculation unit 18 determines when the second charge amount calculated by the second charge amount calculation unit 14 is set as the charge amount of the secondary battery unit 50 (that is, the first charge amount At the correction time when the first charge amount is corrected by replacing the second charge amount, the charge amount difference between the first charge amount calculated by the first charge amount calculation unit 13 and the replaced second charge amount is calculated. Assuming that the first charge amount is SOC1 and the second charge amount is SOC2, the charge amount difference ΔSOC can be represented by the following equation: ΔSOC = SOC2-SOC1.

  The unit capacity error amount calculation unit 20 calculates the unit capacity error amount per unit capacity of the charge amount based on the charge amount difference calculated by the charge amount difference calculation unit 18. Assuming that the unit capacity error amount is ΔEc and the charging / discharging capacity absolute value that reaches the capacity ΔEAh corresponding to the charge amount difference ΔSOC is Ca, it can be calculated by the equation ΔEc = ΔEAh / Ce. Here, assuming that the full charge capacity of the secondary battery unit 50 is FCC, ΔEAh = FCC × ΔSOC / 100. That is, the capacity ΔEAh is obtained by converting the charge amount difference ΔSOC whose unit is% into Ah unit.

  The condition determination unit 16 determines that the second charge amount calculated by the second charge amount calculation unit 14 is the charge amount of the secondary battery unit 50 (that is, the latest correction time of the charge amount) and thereafter. It is determined whether or not a predetermined condition is satisfied based on the charge / discharge capacity and the unit capacity error amount.

  For example, when the unit capacity error amount ΔEc × the charge / discharge capacity c (the absolute value of the charge / discharge capacity after the latest correction of the charge amount) is equal to or more than a predetermined value, the error amount (ΔEc × c) is equal to or more than the predetermined value. , It can be determined that the predetermined condition is satisfied. Accordingly, it is possible to determine whether to correct the first charge amount by replacing the first charge amount with the second charge amount based on the charge amount difference ΔSOC obtained most recently.

  FIG. 17 is a flowchart illustrating a fourth example of the processing procedure for calculating the charge amount by the battery monitoring device 100 according to the present embodiment. The control unit 10 calculates an integrated current SOC (first charge amount) (S71). The calculation frequency of the current integration SOC can be synchronized with the sampling cycle of the current detection of the secondary battery unit 50, and can be, for example, 10 ms. The process of calculating the current integrated SOC is the same as the process shown in FIG.

  The control unit 10 calculates an error amount per unit charge / discharge capacity (unit capacity error amount ΔEc) (S72), and determines whether the error amount (ΔEc × charge / discharge capacity c) is equal to or larger than a predetermined value (S72). S73). The predetermined value can be about 5% to 10% of the SOC at the time of the determination, but is not limited to these values.

  When the error amount (ΔEc × charge / discharge capacity c) is equal to or greater than the predetermined value (YES in S73), the control unit 10 determines whether there is a current zero cross (S74), and when there is a current zero cross (YES in S74). ), It is determined whether or not the switching is from charging to discharging (S75).

  If the switching is from charging to discharging (YES in S75), the control unit 10 determines whether a predetermined time Tcd has elapsed from the time when the current zero cross occurred (S76). The predetermined time Tcd can be, for example, about 0.1 second to 2 seconds. If the predetermined time Tcd has not elapsed (NO in S76), the control unit 10 continues the processing in step S76. If the predetermined time Tcd has elapsed (YES in S76), control unit 10 calculates battery equivalent circuit model SOC (second charge amount) (S77). The process of calculating the battery equivalent circuit model SOC is the same as the process shown in FIG.

  When switching from charging to discharging is not performed (NO in S75), that is, when switching from discharging to charging is performed, the control unit 10 determines whether a predetermined time Tdc has elapsed from the time when the current zero cross occurred. (S78). The predetermined time Tdc can be, for example, about 0.1 second to 2 seconds. When the predetermined time Tdc has not elapsed (NO in S78), the control unit 10 continues the process of step S78. When the predetermined time Tdc has elapsed (YES in S78), the control unit 10 performs the process of step S77.

  The control unit 10 corrects the current integration SOC (S79). The correction of the current integrated SOC is a process of replacing the most recently calculated current integrated SOC with the battery equivalent circuit model SOC when a predetermined time Tcd or Tdc has elapsed.

  The control unit 10 outputs the replaced battery equivalent circuit model SOC as the state of charge SOC of the secondary battery unit 50 (S80), and ends the process. If the error amount (ΔEc × charge / discharge capacity c) is not equal to or more than the predetermined value (NO in S73), or if there is no current zero crossing (NO in S74), the control unit 10 calculates the calculated current integrated SOC by the secondary battery unit. The SOC is output as the charge amount SOC of 50 (S80), and the process ends. Note that the process illustrated in FIG. 17 can be repeatedly performed when charging or discharging of the secondary battery unit 50 continues.

  In the processing illustrated in FIG. 17, the processing of steps S73, S74, S75, S76, and S78 may be omitted. That is, when the error amount (ΔEc × charge / discharge capacity c) is equal to or larger than the predetermined value (YES in S73), the control unit 10 calculates the battery equivalent circuit model SOC (second charge amount) (S77). You may.

  The charge amount calculation device (battery monitoring device 100) of the present embodiment can also be realized using a general-purpose computer including a CPU (processor), a RAM (memory), and the like. That is, a computer program defining the procedure of each process as shown in FIGS. 12 to 17 is loaded into a RAM (memory) provided in the computer, and the computer program is executed by a CPU (processor). Thus, the charge amount calculation device (battery monitoring device 100) can be realized.

  As described above, according to the battery monitoring device 100 (charge amount calculating device) of the present embodiment, the secondary battery unit does not need to be in a no-load state, and even when a current flows through the secondary battery unit. By replacing the charge amount based on the current integration with the charge amount based on the battery equivalent circuit model, the charge amount based on the current integration can be corrected, and the charge amount of the secondary battery unit can be accurately calculated.

  Further, as a comparative example, an open-circuit voltage is calculated from a characteristic line obtained by performing a linear regression operation from the terminal voltage and the current of the secondary battery, and a charge amount calculated based on the open-circuit voltage and a charge amount based on the current integration are calculated. When the difference is equal to or larger than a predetermined value, there is a method of replacing the difference with a charge amount calculated based on the open circuit voltage. However, in such a method, in order to obtain a high-precision characteristic line by performing a first-order regression operation, it is necessary to increase the sampling of the voltage and the current, and a certain degree of variation is required in the sampled voltage and the current. When the vehicle has many opportunities to run at a constant speed, the open-circuit voltage cannot be obtained with high accuracy, and the charge amount cannot be corrected. However, according to the battery monitoring device 100 of the present embodiment, it is not necessary to obtain the primary regression calculation, and the charge / discharge switching timing of the secondary battery unit (accurately, at the time when a predetermined time has elapsed after the charge / discharge switching). The charge amount of the secondary battery unit can be corrected.

  Further, as a comparative example, an open-circuit voltage was calculated from the terminal voltage, the current, and the internal resistance of the secondary battery, and the difference between the charge amount calculated based on the open-circuit voltage and the charge amount based on the current integration became a predetermined value or more. In such a case, there is a method of replacing the charged amount calculated based on the open circuit voltage. However, in such a method, when calculating the open-circuit voltage, the influence of the polarization of the secondary battery is not taken into account, so that the open-circuit voltage cannot be obtained with high accuracy, and the charge amount cannot be corrected. However, according to the battery monitoring apparatus 100 of the present embodiment, since the effect of polarization is included in the battery equivalent circuit model, no error due to polarization occurs by using the battery equivalent circuit model.

  In the above embodiment, the secondary battery is described as a lithium-ion battery, but the secondary battery is not limited to a lithium-ion battery, and can be provided to, for example, a nickel-metal hydride battery, a nickel-cadmium battery, and the like. .

  The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 10 Control part 11 Voltage acquisition part 12 Current acquisition part 13 1st charge amount calculation part 14 2nd charge amount calculation part 15 Open circuit voltage calculation part 16 Condition judgment part 17 Switching judgment part 18 Charge amount difference calculation part 19 Unit time error amount Calculation unit 20 Unit capacity error amount calculation unit 21 Storage unit 22 Timer 50 Secondary battery unit 51 Cell 52 Voltage sensor 53 Current sensor 100 Battery monitoring device

Claims (11)

A charge amount calculation device that calculates a charge amount of a secondary battery,
A voltage acquisition unit that acquires the voltage of the secondary battery,
A current acquisition unit that acquires the current of the secondary battery,
A first calculation unit that integrates the current acquired by the current acquisition unit to calculate a first charge amount of the secondary battery;
A second calculation unit that calculates a second charge amount of the secondary battery based on the voltage acquired by the voltage acquisition unit, the current acquired by the current acquisition unit, and an equivalent circuit model of the secondary battery;
A determination unit for determining whether a predetermined condition is satisfied, and
When the determination unit determines that the predetermined condition is not satisfied, the first charge amount is set as the charge amount of the secondary battery,
When the determination unit determines that the predetermined condition is satisfied, the second charge amount is set as the charge amount of the secondary battery,
Further, at the time when the second charge amount calculated by the second calculation unit is set as the charge amount of the secondary battery, the charge amount difference between the first charge amount and the second charge amount calculated by the first calculation unit is calculated. A charge amount difference calculation unit to be calculated;
A unit time error amount calculation unit that calculates a unit time error amount per unit time of the charge amount based on the charge amount difference calculated by the charge amount difference calculation unit;
With
The determination unit includes:
Based on the elapsed time and the unit time error amount from the time the charge amount and the second amount of charge of the secondary battery calculated by the second calculating unit, charging to determine whether or not to satisfy the predetermined condition Quantity calculation device. A charge amount calculation device that calculates a charge amount of a secondary battery,
A voltage acquisition unit that acquires the voltage of the secondary battery,
A current acquisition unit that acquires the current of the secondary battery,
A first calculation unit that integrates the current acquired by the current acquisition unit to calculate a first charge amount of the secondary battery;
A second calculation unit that calculates a second charge amount of the secondary battery based on the voltage acquired by the voltage acquisition unit, the current acquired by the current acquisition unit, and an equivalent circuit model of the secondary battery;
A determining unit for determining whether a predetermined condition is satisfied;
With
When the determination unit determines that the predetermined condition is not satisfied, the first charge amount is set as the charge amount of the secondary battery,
When the determination unit determines that the predetermined condition is satisfied, the second charge amount is set as the charge amount of the secondary battery,
Further, at the time when the second charge amount calculated by the second calculation unit is set as the charge amount of the secondary battery, the charge amount difference between the first charge amount and the second charge amount calculated by the first calculation unit is calculated. A charge amount difference calculation unit to be calculated;
A unit capacity error amount calculation unit that calculates a unit capacity error amount per unit capacity of the charge amount based on the charge amount difference calculated by the charge amount difference calculation unit;
With
The determination unit includes:
Whether the predetermined condition is satisfied based on the charge / discharge capacity of the secondary battery and the unit capacity error amount after the time when the second charge amount calculated by the second calculator is set as the charge amount of the secondary battery. A charge amount calculation device for determining whether or not the charge amount is present. The determination unit includes:
3. The charge amount calculation device according to claim 1, wherein it is determined that the predetermined condition is not satisfied when a time for integrating the current of the secondary battery is shorter than a predetermined integration time. 4. The voltage acquired by the voltage acquisition unit, the current acquired by the current acquisition unit and an open-circuit voltage calculation unit that calculates the open-circuit voltage of the secondary battery based on the equivalent circuit model of the secondary battery,
The second calculation unit includes:
Based on the correspondence between the open-circuit voltage and the charging amount of the open-circuit voltage and the secondary battery calculated by the open-circuit voltage calculating unit, of claims 1 to 3 for calculating a second amount of charge of the secondary battery A charge amount calculation device according to any one of the preceding claims. A switching determination unit that determines whether to switch the charging and discharging of the secondary battery based on the current acquired by the current acquisition unit,
The determination unit includes:
4. The method according to claim 3, wherein when the time for integrating the current of the secondary battery is equal to or longer than the integration time, it is determined whether the predetermined condition is satisfied according to whether or not switching has been performed by the switching determination unit. 5. Charge calculation device. The second calculation unit includes:
When the switching determination unit determines that there is a charge / discharge switch, after a lapse of a predetermined time from the charge / discharge switch time, the secondary based on the voltage acquired by the voltage acquisition unit and the current acquired by the current acquisition unit. The charge amount calculating device according to claim 5, wherein the second charge amount of the battery is calculated. The charging amount calculation device according to claim 6 , wherein the predetermined time is in a range of 0.1 second to 2 seconds. A computer program for causing a computer to calculate a charge amount of a secondary battery,
The computer,
A voltage acquisition unit that acquires the voltage of the secondary battery,
A current acquisition unit that acquires the current of the secondary battery,
A first calculator that integrates the obtained current to calculate a first charge amount of the secondary battery;
A second calculator that calculates a second charge amount of the secondary battery based on the acquired voltage, current, and an equivalent circuit model of the secondary battery;
A determining unit for determining whether a predetermined condition is satisfied;
Function
When it is determined that the predetermined condition is not satisfied, the first charge amount is set as the charge amount of the secondary battery, and when it is determined that the predetermined condition is satisfied, the second charge amount is set as the charge amount of the secondary battery. processing,
In addition, the computer
A charge amount difference calculating unit that calculates a charge amount difference between the calculated first charge amount and the calculated second charge amount when the calculated second charge amount is set as the charge amount of the secondary battery;
A unit time error amount calculation unit that calculates a unit time error amount per unit time of the charge amount based on the calculated charge amount difference;
Function
A computer program for determining whether or not the predetermined condition is satisfied, based on an elapsed time from a time when the calculated second charge amount is set as the charge amount of the secondary battery and the unit time error amount . A computer program for causing a computer to calculate a charge amount of a secondary battery,
Computer
A voltage acquisition unit that acquires the voltage of the secondary battery,
A current acquisition unit that acquires the current of the secondary battery,
A first calculator that integrates the obtained current to calculate a first charge amount of the secondary battery;
A second calculator that calculates a second charge amount of the secondary battery based on the acquired voltage, current, and an equivalent circuit model of the secondary battery;
A determining unit for determining whether a predetermined condition is satisfied;
Function
When it is determined that the predetermined condition is not satisfied, the first charge amount is set as the charge amount of the secondary battery, and when it is determined that the predetermined condition is satisfied, the second charge amount is set as the charge amount of the secondary battery. Process,
In addition, the computer
A charge amount difference calculating unit that calculates a charge amount difference between the calculated first charge amount and the calculated second charge amount when the calculated second charge amount is set as the charge amount of the secondary battery;
A unit capacity error amount calculation unit that calculates a unit capacity error amount per unit capacity of the charge amount based on the calculated charge amount difference;
With
A computer that determines whether or not the predetermined condition is satisfied based on the charge / discharge capacity of the secondary battery and the unit capacity error amount after the calculated second charge amount is set as the charge amount of the secondary battery. program. A charge amount calculation method for calculating a charge amount of a secondary battery,
The voltage acquisition unit acquires the voltage of the secondary battery,
A current acquisition unit acquires the current of the secondary battery,
The first calculator calculates a first charge amount of the secondary battery by integrating the obtained currents,
A second calculator calculates a second charge amount of the secondary battery based on the acquired voltage and current and an equivalent circuit model of the secondary battery,
The determining unit determines whether a predetermined condition is satisfied,
When it is determined that the predetermined condition is not satisfied, the first charge amount is set as the charge amount of the secondary battery,
When it is determined that the predetermined condition is satisfied, the second charge amount is set as the charge amount of the secondary battery,
further,
At the time when the calculated second charge amount is set as the charge amount of the secondary battery, a charge amount difference calculation unit calculates a charge amount difference between the calculated first charge amount and the second charge amount,
Based on the calculated charge amount difference, a unit time error amount calculation unit calculates a unit time error amount per unit time of the charge amount,
Based second charge amount calculated in the elapsed time and the unit time error amount from the time the charge amount of the of the secondary battery, the charge amount calculating method for determining whether to satisfy the predetermined condition. A charge amount calculation method for calculating a charge amount of a secondary battery,
The voltage acquisition unit acquires the voltage of the secondary battery,
A current acquisition unit acquires the current of the secondary battery,
The first calculator calculates a first charge amount of the secondary battery by integrating the obtained currents,
A second calculator calculates a second charge amount of the secondary battery based on the acquired voltage and current and an equivalent circuit model of the secondary battery,
The determining unit determines whether a predetermined condition is satisfied,
When it is determined that the predetermined condition is not satisfied, the first charge amount is set as the charge amount of the secondary battery,
When it is determined that the predetermined condition is satisfied, the second charge amount is set as the charge amount of the secondary battery,
further,
At the time when the calculated second charge amount is set as the charge amount of the secondary battery, a charge amount difference calculation unit calculates a charge amount difference between the calculated first charge amount and the second charge amount,
Based on the calculated charge amount difference, a unit capacity error amount calculation unit calculates a unit capacity error amount per unit capacity of the charge amount,
It is determined whether or not the predetermined condition is satisfied, based on the charge / discharge capacity of the secondary battery and the unit capacity error amount after the calculated second charge amount is set as the charge amount of the secondary battery. Charge amount calculation method.

Images