JP6631377B2 - 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 HEV (Hybrid Electric Vehicle) and EV (Electric Vehicle) 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 the time of 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 at the time of 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 the discharge 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 the above circumstances, and a charge amount calculation device capable of accurately calculating a charge amount of a secondary battery even when a charge / discharge current is flowing through the secondary battery; It is an object of the present invention to provide a computer program and a charge amount calculation method for realizing an amount calculation 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 acquires a voltage of the secondary battery, and a current 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, and the current acquisition A second calculation unit that calculates a second charge amount of the secondary battery based on the current obtained by the unit and the equivalent circuit model of the secondary battery; and a first charge amount and the second charge amount that are calculated by the first calculation unit. (2) a charge amount difference calculation unit that calculates a charge amount difference of the second charge amount calculated by the calculation unit; and determines whether a predetermined condition is satisfied based on the charge amount difference calculated by the charge amount difference calculation unit. A second condition determining unit that determines that the predetermined condition is satisfied; A correction section that corrects the first charge amount based on coulometric, the correction unit is the charge amount difference calculating unit in the second correction time each calculated before the first correction time and the first correction when the corrected A change amount calculation unit that calculates a change amount of the charge amount difference based on the charge amount difference; and a change amount calculated by the change amount calculation unit and a charge duration or a discharge duration after the first correction time. An error amount calculation unit that calculates an error amount, wherein the condition determination unit determines whether the predetermined condition is satisfied based on whether the error amount calculated by the error amount calculation unit is equal to or greater than a predetermined threshold. you determine whether or not.

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, the process of acquiring the voltage of the secondary battery, the secondary battery a process for obtaining the current, a first process for calculating the charge amount, the obtained voltage and current and wherein based on the equivalent circuit model of the secondary battery secondary acquired current the secondary battery by integrating the A process of calculating a second charge amount of the battery, a process of calculating a difference between the calculated first charge amount and the second charge amount, and determining whether a predetermined condition is satisfied based on the calculated charge amount difference. A determining process , a process of correcting the first charge amount based on the second charge amount when it is determined that the predetermined condition is satisfied , and a first correction time point corrected and a first correction time point before the first correction time point. 2 point of correction A process of calculating a change amount of the charge amount difference based on the charge amount difference calculated in each case; and calculating an error amount based on the calculated change amount and a charge duration or a discharge duration after the first correction time. A calculation process and a process of determining whether or not the predetermined condition is satisfied based on whether the calculated error amount is equal to or greater than a predetermined threshold value are executed .

Charge amount calculating method according to the embodiment of the present invention, the double a charge amount calculation method for calculating the amount of charge of battery, the voltage of the secondary battery acquired by the voltage acquiring unit, the current of the secondary battery 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 calculator calculates a second charge amount of the secondary battery based on the calculated charge amount, calculates a charge amount difference between the calculated first charge amount and the second charge amount, and calculates the calculated charge amount. A condition determination unit determines whether or not a predetermined condition is satisfied based on the amount difference, and when it is determined that the predetermined condition is satisfied, a correction unit corrects the first charge amount based on the second charge amount. Then, calculation is performed at the corrected first correction time point and at the second correction time point before the first correction time point. A change amount of the charge amount difference is calculated based on the charge amount difference, and an error amount is calculated based on the calculated change amount and a charge duration or a discharge duration after the first correction time, and the calculated error is calculated. the amount is based on whether it is greater than the predetermined threshold value, determining whether or not to satisfy the predetermined condition.

  According to the present invention, the charge amount of the secondary battery can be accurately calculated even when the 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. 3 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 illustrating an example of a transition of a voltage after charging of a secondary battery unit of the present embodiment is started. FIG. 5 is a schematic diagram showing an example of a change in voltage after the secondary battery unit 50 of the present embodiment starts discharging. FIG. 4 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. FIG. 4 is an explanatory diagram illustrating an example of a method of calculating a unit capacity change amount by the battery monitoring device 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. 4 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 a first example of a processing procedure for calculating a charged amount by the battery monitoring device according to the present embodiment. 6 is a flowchart illustrating an example of a processing procedure of calculating a current integrated SOC by the battery monitoring device according to the present embodiment. 5 is a flowchart illustrating an example of a processing procedure for 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 for calculating a unit capacity change amount by the battery monitoring device according to the present embodiment. 6 is a flowchart illustrating an example of a processing procedure for calculating an error amount 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.

[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 acquires a voltage of the secondary battery, and a current 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, and the current acquisition A second calculation unit that calculates a second charge amount of the secondary battery based on the current obtained by the unit and the equivalent circuit model of the secondary battery; and a first charge amount and the second charge amount that are calculated by the first calculation unit. (2) a charge amount difference calculation unit that calculates a charge amount difference of the second charge amount calculated by the calculation unit; and determines whether a predetermined condition is satisfied based on the charge amount difference calculated by the charge amount difference calculation unit. A second condition determining unit that determines that the predetermined condition is satisfied; And a correcting section that corrects the first charge amount based on coulometric.

  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 and current, and an equivalent circuit of the secondary battery. A second calculator for calculating a second charge amount of the secondary battery based on the model; a charge amount difference calculator for calculating a charge amount difference between the calculated first charge amount and the second charge amount; A condition determination unit that determines whether a predetermined condition is satisfied based on the amount difference; and a correction unit that corrects the first charge amount based on the second charge amount when it is determined that the predetermined condition is satisfied. Let it work.

  A charging amount calculating method according to an embodiment of the present invention is a charging amount calculating device that calculates a charging amount of a secondary battery, wherein a voltage obtaining unit obtains a voltage of the secondary battery, 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 calculator calculates a second charge amount of the secondary battery based on the calculated charge amount, calculates a charge amount difference between the calculated first charge amount and the second charge amount, and calculates the calculated charge amount. A condition determination unit determines whether or not a predetermined condition is satisfied based on the amount difference, and when it is determined that the predetermined condition is satisfied, a correction unit corrects the first charge amount based on the second charge amount. I do.

  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 the first charge amount of the secondary battery by integrating the currents acquired by the current acquisition 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 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, it 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, a parallel circuit of a resistor and a capacitor, and the like. Note that the voltage and the current are values when the secondary battery is being charged or discharged, and the secondary battery is not in a no-load state.

  The charge amount difference calculator calculates a charge amount difference between the first charge amount calculated by the first calculator and the second charge amount calculated by the second calculator. Assuming that the first charge amount is SOC1 and the second charge amount is SOC2, the charge amount difference ΔSOC can be calculated by, for example, an expression of ΔSOC = SOC2−SOC1.

  The condition determination unit determines whether a predetermined condition is satisfied based on the charge amount difference calculated by the charge amount difference calculation unit. The predetermined condition can be, for example, a condition indicating whether or not the error of the current integration exceeds an allowable range. That is, when the charge amount difference calculated by the charge amount difference calculation unit is large, it is considered that the error of the current integration exceeds the allowable range, and it can be determined that the predetermined condition is satisfied. Conversely, when the charge amount difference calculated by the charge amount difference calculation unit is small, it can be determined that the predetermined condition is not satisfied.

  When the condition determination unit determines that the predetermined condition is satisfied, the correction unit corrects the first charge amount based on the second charge amount. Correcting the first charge amount based on the second charge amount means, for example, replacing the first charge amount with the second charge amount, and replacing the charge amount of the secondary battery with the first charge amount. Quantity.

  According to the above-described 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, and the charge amount of the secondary battery can be accurately calculated even when the charge / discharge current is flowing through the secondary battery.

  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, and the condition determination unit includes: 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 the 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.

  The condition determining unit determines whether or not a predetermined condition is satisfied according to the presence or absence of the switching determined by the switching determining unit. For example, when the switching determination unit determines that the charge / discharge has been switched, 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 charge / discharge of the secondary battery is switched, the second charge amount based on the equivalent circuit model that is more accurate than the accuracy of the first charge amount based on the current integration can be used. In addition, the amount of charge of the secondary battery can be accurately calculated.

  The charge amount calculation device according to the embodiment of the present invention may further include a charge amount calculated by the charge amount difference calculation unit at each of a first correction time point corrected by the correction unit and a second correction time point before the first correction time point. A change amount calculation unit that calculates a change amount of the charge amount difference based on the difference; and an error amount based on the change amount calculated by the change amount calculation unit and the charge duration or the discharge duration after the first correction time point. An error amount calculation unit that calculates the error amount, and the condition determination unit determines whether the predetermined condition is satisfied based on whether an error amount calculated by the error amount calculation unit is equal to or greater than a predetermined threshold. Is determined.

  The change amount calculation unit is configured to calculate the change amount of the charge amount difference based on the charge amount difference calculated by the charge amount difference calculation unit at each of the first correction time point corrected by the correction unit and the second correction time point before the first correction time point. Is calculated. Assuming that the charge amount difference at the first correction time point t is ΔSOC (t) and the charge amount difference at the second correction time point (t−1) is ΔSOC (t−1), the change amount is ΔSOC (t) −ΔSOC ( t-1) can be calculated. Here, the charge amount difference ΔSOC can be calculated by ΔSOC = SOC2-SOC1.

  The error amount calculation unit calculates the error amount based on the change amount calculated by the change amount calculation unit and the charge continuation time or the discharge continuation time after the first correction time point. For example, assuming that the time difference between the first correction time t and the second correction time (t-1) is Δt, the amount of change per unit time is {ΔSOC (t) −ΔSOC (t−1)} / Δt. Can be represented by When the charge continuation time or the discharge continuation time after the first correction time point (t) is represented by Tp, the error amount is represented by, for example, a formula of Tp × {ΔSOC (t) −ΔSOC (t−1)} / Δt. Can be. That is, the error amount represents an index indicating how much the change amount increases as the charge duration time or the discharge duration time elapses.

  The condition determination unit determines whether or not a predetermined condition is satisfied, based on whether or not the error amount calculated by the error amount calculation unit is equal to or greater than a predetermined threshold. For example, when the error amount is equal to or more than a predetermined threshold, it can be determined that the predetermined condition is satisfied.

  According to the above configuration, the first charge amount can be corrected by replacing the first charge amount with the second charge amount based on the error amount regardless of whether the charge / discharge of the secondary battery is switched. The amount of charge for the next battery can be accurately calculated.

  The charge amount calculation device according to the embodiment of the present invention includes a capacity calculation unit that calculates the charged or discharged capacity between the first correction time point and the second correction time point, and a change amount calculated by the change amount calculation unit. A unit capacity change amount calculation unit for calculating a unit capacity change amount per unit capacity based on the capacity calculated by the capacity calculation unit, wherein the error amount calculation unit is calculated by the unit capacity change amount calculation unit. An error amount is calculated based on a unit capacity change amount and a charge capacity or a discharge capacity of the secondary battery after the first correction time point.

  The capacity calculation unit calculates the charged or discharged capacity between the first correction time point and the second correction time point. The capacity represents, for example, the integration of the charging current and the charging time between the first correction time and the second correction time, or the integration of the discharge current and the discharging time between the first correction time and the second correction time in Ah units. Things.

  The unit capacity change amount calculation unit calculates a unit capacity change amount per unit capacity based on the change amount calculated by the change amount calculation unit and the capacity calculated by the capacity calculation unit. The amount of change between the first correction time point (t) and the second correction time point (t-1) is defined as ΔSOC (t) −ΔSOC (t−1), and the capacity between the first correction time point and the second correction time point is denoted by C. Then, the unit capacitance change amount can be expressed by an expression of {ΔSOC (t) −ΔSOC (t−1)} / C.

  The error amount calculation unit calculates the error amount based on the unit capacity change amount calculated by the unit capacity change amount calculation unit and the charge capacity or the discharge capacity of the secondary battery after the first correction time. Assuming that the charge capacity or the discharge capacity of the secondary battery after the first correction time is Cp, the error amount can be expressed by, for example, an expression of Cp × {ΔSOC (t) −ΔSOC (t−1)} / C}. it can. That is, the error amount indicates an index indicating how much the change amount increases with an increase in the charge capacity or the discharge capacity of the secondary battery.

  According to the above configuration, the first charge amount can be corrected by replacing the first charge amount with the second charge amount based on the error amount regardless of whether the charge / discharge of the secondary battery is switched. The amount of charge for the next battery can be accurately calculated.

  In the charge amount calculation device according to the embodiment of the present invention, the condition determination unit may satisfy the predetermined condition based on whether a charge amount difference calculated by the charge amount difference calculation unit is equal to or greater than a predetermined value. It is determined whether or not to perform.

  The condition determination unit determines whether a predetermined condition is satisfied based on whether the charge amount difference calculated by the charge amount difference calculation unit is equal to or greater than a predetermined value. When the error of the current integration exceeds the allowable range, the charge amount difference ΔSOC is considered to increase. Therefore, when the charge amount difference ΔSOC is equal to or more than a predetermined value, it can be determined that the predetermined condition is satisfied.

  With the above-described configuration, the first charge amount can be corrected by replacing the first charge amount with the second charge amount based on the charge amount difference ΔSOC regardless of whether the charge / discharge of the secondary battery is switched. In addition, 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 condition determination unit satisfies the predetermined condition when a charge duration or a discharge duration after the time corrected by the correction unit is a predetermined time or more. It is determined whether or not.

  The condition determination unit determines whether or not a predetermined condition is satisfied when the charge duration or the discharge duration after the time corrected by the correction unit is equal to or longer than a predetermined time. It is considered that the longer the charge duration or discharge duration, the more the current integration error increases. Therefore, when the charge duration or the discharge duration is equal to or longer than the predetermined time, it is determined whether or not a predetermined condition is satisfied in order to determine whether or not the current integration error exceeds an allowable range. Thereby, it is possible to prevent the error of the current integration from exceeding the allowable range.

  The charge amount calculation device according to the embodiment of the present invention includes an open circuit voltage 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 calculation unit calculates the open-circuit voltage based on the open-circuit voltage calculated by the open-circuit voltage calculation unit and the correspondence between the open-circuit voltage of the secondary battery and the amount of charge. Is calculated.

  The open-circuit voltage calculation unit calculates the open-circuit voltage OCV of the secondary battery based on the voltage Vb acquired by the voltage acquisition unit, the current Ib acquired by the current acquisition 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 a 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 a 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 the second charge amount for correcting the first charge amount based on the current integration even when the charge / discharge current flows through the secondary battery. Can be calculated.

[Details of the embodiment of the present invention]
Hereinafter, an embodiment of a charge amount calculating device according to the present invention will be described with reference to the drawings. 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 in 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 electric power by the rotation of the engine of the vehicle, and outputs a direct current by a rectifier circuit provided therein to charge the battery 65. The generator 62 charges the battery 65 and the secondary battery unit 50 when the relay 61 is on. The relays 61 and 63 are turned on and off 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-circuit voltage calculation unit 15, a condition determination unit. 16, a switching determination unit 17, a charge amount difference calculation unit 18, an error amount calculation unit 19, a capacity calculation unit 20, a unit capacity change amount calculation unit 21, a storage unit 22, a timer 23 for clocking, and the like.

  The voltage acquiring 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. Note that the control unit 10 can control the sampling period for acquiring the voltage and the current. 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 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 errors in the current value that gradually increase and accumulate in the process of integrating the current (for example, errors in the current sensor 53). 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 (In FIG. 3, FIG. 3 shows a configuration in which four parallel circuits each including resistors R2 to R5 and each of capacitors C2 to C5 are connected in series) and the like. 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 electrolytic solution bulk includes the conduction resistance of lithium (Li) ions in the electrolytic solution 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 charge amount difference calculator 18 calculates the first charge amount (current integrated SOC) calculated by the first charge amount calculator 13 and the second charge amount (battery equivalent circuit model SOC) calculated by the second charge amount calculator 14. Calculate the charge amount difference. Assuming that the first charge amount is SOC1 and the second charge amount is SOC2, the charge amount difference ΔSOC can be calculated by, for example, an expression of ΔSOC = SOC2−SOC1.

  The condition determination unit 16 determines whether or not a predetermined condition is satisfied based on the charge amount difference calculated by the charge amount difference calculation unit 18. The predetermined condition can be, for example, a condition indicating whether or not the error of the current integration exceeds an allowable range. That is, when the charge amount difference calculated by the charge amount difference calculation unit 18 is large, it is considered that the error of the current integration exceeds the allowable range, and it can be determined that the predetermined condition is satisfied. Conversely, when the charge amount difference calculated by the charge amount difference calculation unit 18 is small, it can be determined that the predetermined condition is not satisfied.

  The control unit 10 has a function as a correction unit, and corrects the first charge amount based on the second charge amount when the condition determination unit 16 determines that the predetermined condition is satisfied. Correcting the first charge amount based on the second charge amount means, for example, replacing the first charge amount with the second charge amount, and replacing the charge amount of the secondary battery unit 50 with the first charge amount. It can be two charge amounts.

  More specifically, when the condition determination unit 16 determines that the predetermined condition is not satisfied (when it is considered that the error of the current integration does not exceed the allowable range), the control unit 10 sets the first charge amount to the secondary battery. The charge amount of the unit 50 is assumed. When the condition determination unit 16 determines that the predetermined condition is satisfied (when the current integration error is considered to exceed the allowable range), the control unit 10 uses the second charge amount instead of the first charge amount. The charge amount of the battery unit 50 is set (the first charge amount is replaced with the second charge amount). Correcting the first charge amount with the second charge amount is also referred to as current integrated SOC correction.

  According to the above-described 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, and the charge amount of the secondary battery unit 50 can be accurately calculated even when the charge / discharge current flows through the secondary battery unit 50. it can.

  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.

  The condition determination unit 16 determines whether or not a predetermined condition is satisfied, based on the presence or absence of switching determined by the switching determination unit 17. 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.

  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 increases. Therefore, when the charge / discharge of the secondary battery unit 50 is switched, it is possible to use the second charge amount based on the equivalent circuit model that is more accurate than the accuracy of the first charge amount based on the current integration. Since it is possible, the charge amount of the secondary battery unit 50 can be accurately calculated.

  In the present embodiment, even when the switching determination unit 17 determines that there is no switching between charging and discharging, if the charging amount difference calculated by the charging amount difference calculating unit 18 is large, the error of the current integration falls within the allowable range. Since it is considered to exceed the predetermined condition, it is determined that the predetermined condition is satisfied. Therefore, the first charge amount is corrected with the second charge amount. The number of corrections can be increased, and the amount of charge of the secondary battery unit 50 can be accurately calculated even when a charge / discharge current is flowing through the secondary battery unit 50.

  In addition, when the switching determination unit 17 determines that there is a charge / discharge switch, the second charge amount calculation unit 14 obtains the voltage and current acquisition units 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 can be calculated based on the current obtained in step S12. For the predetermined time, different values may be used for switching from charging to discharging and 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, so that the second charging amount based on the equivalent circuit model can be reduced. Accuracy can be increased. 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 calculating unit 15 calculates the open-circuit voltage OCV of the secondary battery unit 50 based on the voltage Vb obtained by the voltage obtaining unit 11, the current Ib obtained by the current obtaining 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 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. 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 illustrating an example of a change in voltage after the discharge of the secondary battery unit 50 according to the present embodiment is started. 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-circuit 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 various electrochemical reaction delays following the stepwise voltage drop. The relationship of OCV = Vb-overvoltage is established between the acquired (detected) voltage Vb, the overvoltage, and the 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 charged 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 charge amount increases as the open-circuit voltage of the secondary battery unit 50 increases. 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 a calculation 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 is corrected based on the current integration even when the charge / discharge current is flowing through the secondary battery unit 50. The second charge amount can be calculated.

  Next, a process for determining whether or not a predetermined condition is satisfied based on the charge amount difference calculated by the charge amount difference calculation unit 18 will be described. Specifically, the change amount of the charge amount difference indicating how much the charge amount difference at the time of performing the current integrated SOC correction has changed from the charge amount difference at the time of performing the previous current integrated SOC correction is used. First, a case where the unit capacitance change amount is used will be described.

  It is assumed that the control unit 10 has performed the current integration SOC correction at each of the first correction time and the second correction time before the first correction time. The charge amount difference calculation unit 18 has a function as a change amount calculation unit, and based on the charge amount difference calculated at each of the first correction time point and the second correction time point corrected by the control unit 10, the change of the charge amount difference. Calculate the amount.

  Assuming that the charge amount difference at the first correction time point t is ΔSOC (t) and the charge amount difference at the second correction time point (t−1) is ΔSOC (t−1), the change amount is ΔSOC (t) −ΔSOC ( t-1) can be calculated. Here, the charge amount difference ΔSOC can be calculated by ΔSOC = SOC2-SOC1.

  The capacity calculator 20 calculates the charged or discharged capacity between the first correction time point and the second correction time point. The capacity represents, for example, the integration of the charging current and the charging time between the first correction time and the second correction time, or the integration of the discharge current and the discharging time between the first correction time and the second correction time in Ah units. Things.

  The unit capacity change amount calculation unit 21 calculates a unit capacity change amount per unit capacity based on the change amount calculated by the charge amount difference calculation unit 18 (change amount calculation unit) and the capacity calculated by the capacity calculation unit 20. . The amount of change between the first correction time point (t) and the second correction time point (t-1) is defined as ΔSOC (t) −ΔSOC (t−1), and the capacity between the first correction time point and the second correction time point is denoted by C. Then, the unit capacitance change amount can be expressed by an expression of {ΔSOC (t) −ΔSOC (t−1)} / C.

  FIG. 7 is an explanatory diagram illustrating an example of a method of calculating the unit capacity change amount by the battery monitoring device 100 according to the present embodiment. The upper diagram shows the current flowing through the secondary battery unit 50, and the lower diagram shows the transition of the change in the charge amount difference ΔSOC. In the lower diagram, the graph shown by the solid line represents the current integrated SOC (first charge amount), and the graph shown by the broken line represents the battery equivalent circuit model SOC (second charge amount). In the example of FIG. 7, at the second correction time point (t-1), the mode is switched from discharging to charging, and the current integration SOC correction is performed at the second correction time point (t-1). After the second correction time point (t-1), the state of charge continues. At the first correction time point t, the mode is switched from charging to discharging, and the current integrated SOC correction is performed at the first correction time point t.

  The shaded area in the upper diagram represents the capacity C charged between the first correction time and the second correction time. The unit of the capacitance C is Ah. Assuming that the charge amount difference at the first correction time point t is ΔSOC (t) and the charge amount difference at the second correction time point (t−1) is ΔSOC (t−1), the difference between the first correction time point and the second correction time point is obtained. The amount of change in the charge amount difference can be calculated by the equation ΔSOC (t) −ΔSOC (t−1). Then, the unit capacitance change amount can be expressed by an expression of {ΔSOC (t) −ΔSOC (t−1)} / C.

  The error amount calculation unit 19 calculates the error amount based on the unit capacity change amount calculated by the unit capacity change amount calculation unit 21 and the charge capacity or the discharge capacity of the secondary battery unit 50 after the first correction time. Assuming that the charge capacity or the discharge capacity of the secondary battery unit 50 after the first correction time is Cp, the error amount is represented by, for example, an expression of Cp × {ΔSOC (t) −ΔSOC (t−1)} / C}. be able to. That is, the error amount indicates an index indicating how much the change amount increases with an increase in the charge capacity or the discharge capacity of the secondary battery unit 50.

  The condition determination unit 16 determines whether or not a predetermined condition is satisfied, based on whether or not the error amount calculated by the error amount calculation unit 19 is equal to or greater than a predetermined threshold. For example, when the error amount is equal to or more than a predetermined threshold, it can be determined that the predetermined condition is satisfied.

  According to the above configuration, the first charge amount can be corrected by replacing the first charge amount with the second charge amount based on the error amount regardless of whether the charge / discharge of the secondary battery unit 50 is switched. In addition, the amount of charge in the secondary battery unit 50 can be accurately calculated.

  In the above example, the case where the unit capacitance change amount is used has been described, but the present invention is not limited to this. Hereinafter, another example will be described.

  That is, the error amount calculation unit 19 can also calculate the error amount based on the change amount calculated by the charge amount difference calculation unit 18 and the charge continuation time or the discharge continuation time after the first correction time point. For example, assuming that the time difference between the first correction time t and the second correction time (t-1) is Δt, the amount of change per unit time is {ΔSOC (t) −ΔSOC (t−1)} / Δt. Can be represented by When the charge continuation time or the discharge continuation time after the first correction time point (t) is represented by Tp, the error amount is represented by, for example, a formula of Tp × {ΔSOC (t) −ΔSOC (t−1)} / Δt. Can be. That is, the error amount represents an index indicating how much the change amount increases as the charge duration time or the discharge duration time elapses.

  Also in this case, the condition determination unit 16 determines whether or not the predetermined condition is satisfied based on whether or not the error amount calculated by the error amount calculation unit 19 is equal to or larger than a predetermined threshold. For example, when the error amount is equal to or more than a predetermined threshold, it can be determined that the predetermined condition is satisfied.

  According to the above configuration, the first charge amount can be corrected by replacing the first charge amount with the second charge amount based on the error amount regardless of whether the charge / discharge of the secondary battery unit 50 is switched. In addition, the amount of charge in the secondary battery unit 50 can be accurately calculated.

  Further, it is also possible to set when the determination processing by the condition determination unit 16 is performed. For example, when the charge continuation time or the discharge continuation time after the correction time point at which the control unit 10 performs the current integration SOC correction is equal to or longer than a predetermined time, the condition determination unit 16 determines whether or not a predetermined condition is satisfied. Can be. The predetermined time can be, for example, 1 minute, 2 minutes, 5 minutes, or the like, but is not limited to these numerical values.

  If the charge continuation time or the discharge continuation time becomes long after the switching of the charging and discharging of the secondary battery unit 50, the error of the current integration is considered to increase. Therefore, when the charge duration or the discharge duration is equal to or longer than the predetermined time, it is determined whether or not a predetermined condition is satisfied in order to determine whether or not the current integration error exceeds an allowable range. Thereby, it is possible to prevent the error of the current integration from exceeding the allowable range.

  FIG. 8 is a schematic diagram illustrating a main part of a process of calculating the amount of charge 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 cycle (for example, 10 ms), the first charge amount calculation unit 13 performs a current integration process and performs the current integration at the sampling cycle. 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 period (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 whether there is a current zero-crossing, that is, a determination process of whether charging / discharging is switched) 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 time when a predetermined time (for example, about 0.1 second to about 2 seconds) has elapsed from a time point (charge / discharge switching time).

  The error amount calculation unit 19 calculates the difference between the charge amount of the first charge amount calculated by the first charge amount calculation unit 13 and the charge amount of the second charge amount calculated by the second charge amount calculation unit 14 at the timing when the current integrated SOC correction is performed. (SOC difference) is calculated, and the change amount of the charge amount difference is calculated using the charge amount difference calculated at the previous timing of the current integrated SOC correction. The error amount calculation unit 19 calculates the amount of change in the charge amount difference and the capacity charged or discharged in the secondary battery unit 50 during the period from the previous timing of the current integrated SOC correction to the current current integrated SOC correction timing. The amount of change in the unit capacity is calculated, and the amount of error is calculated using the capacity charged or discharged in the secondary battery unit 50 after the timing of the current integrated SOC correction, and the calculated amount of error and a predetermined threshold value are calculated. To compare.

  The control unit 10 corrects the first charge amount by replacing the first charge amount with the second charge amount when the predetermined time elapse trigger is generated or when the error amount becomes equal to or more than the predetermined threshold value. . That is, the control unit 10 performs the current integrated SOC correction at the time when the predetermined time elapse trigger is generated or when the error amount becomes equal to or more than the predetermined threshold, and the second charge amount calculation unit 14 calculates The second charge amount is output as the charge amount SOC of the secondary battery unit 50.

  FIG. 9 is an explanatory diagram illustrating an example of a current waveform of the secondary battery unit 50 according to the present embodiment. In FIG. 9, 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. 9, 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. 10 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. 10, the horizontal axis indicates time, and the vertical axis indicates the state of charge SOC. In FIG. 10, 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. 9. Further, the graph indicated by the “battery equivalent circuit model” indicates 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)” shows a transition from time 0 when the currents illustrated in FIG. 9 are integrated without error, and represents a true value of current integration.

  As can be seen from FIG. 10, the first charge amount based on the current integration has a larger deviation from the true value of the current integration with time, and the error gradually increases. In addition, while the time elapsed from time 0 is short, 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 seen that the second charge amount tends to approach the true value of the current integration at the timing when the switching between charging and discharging occurs.

  FIG. 11 is an explanatory diagram illustrating an example of 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 indicates time, and the vertical axis indicates the state of charge SOC. In FIG. 11, the predetermined time elapse trigger is generated many times. In addition, when the discharge state continues and the error amount becomes equal to or more than the predetermined threshold value, it can be seen that the charge amount of the secondary battery unit 50 is corrected as indicated by the symbol A in the figure. In this manner, the number of times of current integration SOC correction can be increased as compared with the case where current integration SOC correction is performed only at the time of switching between charging and discharging. The amount of charge of the battery unit 50 can be accurately calculated. Although FIG. 11 illustrates that the discharging state continues and the amount of charge of the secondary battery unit 50 is corrected when the error amount becomes equal to or more than a predetermined threshold, the charging state continues. The same applies to the case. Also, in FIG. 11, for simplicity, only one point in time when the error amount is equal to or more than the predetermined threshold value is illustrated by a code A, but actually, when the error amount is equal to or more than the predetermined threshold value, May appear more than once.

  FIG. 12 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. 12, the horizontal axis represents time, and the vertical axis represents an error in the state of charge SOC. In FIG. 12, 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. 12, not only the timing when the predetermined time lapse trigger is generated, but also when the discharge state continues and the error amount becomes equal to or more than the predetermined threshold value, the secondary battery unit 50 is set to reduce the error. It can be seen that the charge amount is corrected.

  Next, the operation of the battery monitoring device 100 according to the present embodiment will be described. FIGS. 13 and 14 are flowcharts showing a first example of a procedure for calculating the amount of charge by the battery monitoring device 100 according to the present embodiment. In the following, 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 there is a current zero cross (S12). If there is a current zero cross (YES in S12), the control unit 10 determines whether or not switching from charging to discharging is performed (S13). If the switching is from charging to discharging (YES in S13), the control unit 10 determines whether a predetermined time Tcd has elapsed from the time when the current zero cross occurred (S14). 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 S14), the control unit 10 continues the processing in step S14. When the predetermined time Tcd has elapsed (YES in S14), the control unit 10 performs the process of step S16 described below.

  When switching from charging to discharging is not performed (NO in S13), 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. (S15). 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 S15), the control unit 10 continues the process of step S15. When the predetermined time Tdc has elapsed (YES in S15), the control unit 10 performs the processing of step S16 described below.

  The control unit 10 calculates a battery equivalent circuit model SOC (second charge amount) (S16). Details of the calculation process of the battery equivalent circuit model SOC will be described later. The control unit 10 corrects the current integration SOC (S17). 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 the predetermined time Tcd or Tdc has elapsed.

  The control unit 10 calculates a unit capacity change amount (S18). The details of the unit capacity change amount calculation processing will be described later. The control unit 10 outputs the replaced battery equivalent circuit model SOC as the state of charge SOC of the secondary battery unit 50 (S19).

  The control unit 10 determines whether the charge duration or the discharge duration is equal to or longer than a predetermined time (S20). The predetermined time can be, for example, 1 minute, 2 minutes, 5 minutes, or the like, but is not limited to these numerical values. When the charge duration or the discharge duration is equal to or longer than the predetermined time (YES in S20), the control unit 10 calculates an error amount (S21). The details of the error amount calculation processing will be described later.

  The control unit 10 determines whether or not the calculated error amount is equal to or greater than a threshold value (S22), and if the error amount is equal to or greater than the threshold value (YES in S22), corrects the current integrated SOC (S23). 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 the error amount becomes equal to or larger than the threshold value. The threshold value may be a numerical value corresponding to about 5% to 10% of the SOC at the time of the determination, but is not limited thereto.

  The control unit 10 calculates the unit capacity change amount (S24), and outputs the replaced battery equivalent circuit model SOC as the charge amount SOC of the secondary battery unit 50 (S25). If there is no current zero cross (NO in S12), if the charge duration or the discharge duration is not equal to or longer than the predetermined time (NO in S20), or if the error amount is not equal to or greater than the threshold (NO in S22), the control unit 10 The calculated current integrated SOC is output as the state of charge SOC of the secondary battery unit 50 (S25).

  The control unit 10 determines whether or not to end the process (S26). If the process is not to be ended (NO in S26), the process is continued from step S11. If the process is to be ended (YES in S26), the process is terminated. To end. Note that the processes shown in FIGS. 13 and 14 can be repeatedly performed when charging or discharging of the secondary battery unit 50 continues.

  FIG. 15 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. 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. 16 is a flowchart illustrating an example of a processing procedure for calculating a 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 the 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. 17 is a flowchart illustrating an example of a processing procedure of calculating the unit capacity change amount by the battery monitoring device 100 according to the present embodiment. The control unit 10 obtains the correction amount (the SOC difference between the current integrated SOC and the battery equivalent circuit model SOC) at the first correction time point when the current integrated SOC is corrected (S121), and obtains the correction amount of the previous current integrated SOC. The correction amount (the SOC difference between the current integrated SOC and the battery equivalent circuit model SOC) at the second correction time point (before the first correction time point) is acquired (S122).

  The control unit 10 calculates a change amount of the charge amount difference between the correction amount (charge amount difference) at the first correction time point and the correction amount (charge amount difference) at the second correction time point (S123). Assuming that the charge amount difference at the first correction time point t is ΔSOC (t) and the charge amount difference at the second correction time point (t−1) is ΔSOC (t−1), the change amount is ΔSOC (t) −ΔSOC ( t-1) can be calculated.

  The control unit 10 calculates the charged or discharged capacity between the first correction time point and the second correction time point (S124), and calculates the unit capacity change amount based on the change amount of the charge amount difference and the calculated capacity ( S125), the process ends. In addition, assuming that the capacity C is charged or discharged between the first correction time point and the second correction time point, the unit capacity change amount can be calculated by the formula {ΔSOC (t) −ΔSOC (t−1)} / C. it can.

  FIG. 18 is a flowchart illustrating an example of a processing procedure for calculating an error amount by the battery monitoring device 100 according to the present embodiment. The control unit 10 acquires the amount of change in the unit capacity calculated in the process illustrated in FIG. 17 (S131), and acquires the charge continuation time or the discharge continuation time after the first correction time point when the current integrated current SOC is corrected (S132). ).

  The control unit 10 acquires the charging current or the discharging current after the first correction time (S133). By integrating the charging current and the charging continuation time after the first correction time, the capacity charged to the secondary battery unit 50 after the first correction time can be obtained. Further, by integrating the discharge current and the discharge continuation time after the first correction time, the capacity discharged from the secondary battery unit 50 after the first correction time can be obtained.

  The control unit 10 calculates an error amount based on the unit capacity change amount and the capacity charged to the secondary battery unit 50 or the capacity discharged from the secondary battery unit 50 after the first correction time point (S134), and the processing is performed. To end.

  In the above-described first example, the charge amount is corrected by replacing the current integrated SOC with the battery equivalent circuit model SOC using the error amount. However, the present invention is not limited to this. For example, as a second example, the SOC difference (charge amount difference) between the current integration SOC and the battery equivalent circuit model SOC can be used. Hereinafter, the second example will be described.

  The condition determination unit 16 determines whether or not a predetermined condition is satisfied based on whether or not the charge amount difference calculated by the charge amount difference calculation unit 18 is equal to or more than a predetermined value. When the error of the current integration exceeds the allowable range, the charge amount difference ΔSOC is considered to increase. Therefore, when the charge amount difference ΔSOC is equal to or more than a predetermined value, it can be determined that the predetermined condition is satisfied.

  When the condition determination unit 16 determines that the predetermined condition is satisfied, the control unit 10 corrects the first charge amount based on the second charge amount. Correcting the first charge amount based on the second charge amount means, for example, replacing the first charge amount with the second charge amount, and replacing the charge amount of the secondary battery unit 50 with the first charge amount. It can be two charge amounts.

  According to the above-described configuration, the first charge amount can be corrected by replacing the first charge amount with the second charge amount based on the charge amount difference ΔSOC regardless of whether the charge / discharge of the secondary battery unit 50 is switched. Therefore, the amount of charge in the secondary battery unit 50 can be accurately calculated.

  FIG. 19 is a flowchart illustrating a second example of the processing procedure for calculating the charged amount by the battery monitoring device 100 according to the present embodiment. 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 there is a current zero cross (S32), and if there is a current zero cross (YES in S32), determines whether switching from charging to discharging is performed (S33). If the switching is from charging to discharging (YES in S33), the control unit 10 determines whether a predetermined time Tcd has elapsed from the time when the current zero cross occurred (S34). The predetermined time Tcd can be, for example, about 0.1 second to 2 seconds.

  When the predetermined time Tcd has not elapsed (NO in S34), the control unit 10 continues the process of step S34. When the predetermined time Tcd has elapsed (YES in S34), the control unit 10 performs the processing of step S36 described later.

  When switching from charging to discharging is not performed (NO in S33), 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. (S35). 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 S35), the control unit 10 continues the processing of step S35. When the predetermined time Tdc has elapsed (YES in S35), the control unit 10 performs the process of step S36 described later.

  The control unit 10 calculates a battery equivalent circuit model SOC (second charge amount) (S36). The process of calculating the battery equivalent circuit model SOC is the same as the process shown in FIG. The control unit 10 calculates an SOC difference between the current integrated SOC and the battery equivalent circuit model SOC (S37), and determines whether or not the SOC difference is equal to or larger than a predetermined value (S38). 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 SOC difference is equal to or more than the predetermined value (YES in S38), control unit 10 corrects current integrated SOC (S39). 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 the 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 (S40), and ends the process. When there is no current zero cross (NO in S32), the control unit 10 determines whether the charge duration or the discharge duration is equal to or longer than a predetermined time (S41). The predetermined time can be, for example, 1 minute, 2 minutes, 5 minutes, or the like, but is not limited to these transition values.

  When the charge duration or the discharge duration is equal to or longer than the predetermined time (YES in S41), the control unit 10 performs the process of step S36. If the SOC difference is not equal to or greater than the predetermined value (NO in S38), or if the charge continuation time or the discharge continuation time is not equal to or more than the predetermined time (NO in S41), control unit 10 calculates the calculated current integrated SOC by the secondary battery unit. The charge amount SOC is output as 50 (S40), and the process ends. Note that the process illustrated in FIG. 19 can be repeatedly performed when charging or discharging of the secondary battery unit 50 continues.

  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, as shown in FIGS. 13 to 19, a computer program that defines the procedure of each processing 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 is flowing 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 a terminal voltage and a current of a secondary battery, and a charge amount calculated based on the open-circuit voltage and a charge amount based on current integration are calculated. When the difference is equal to or more 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 the sampled voltage and the current need to have some variation. If 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.

  In addition, 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, the influence of the polarization of the secondary battery is not taken into account when calculating the open-circuit voltage, 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 may 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 Error amount calculation part Reference Signs List 20 Capacity calculation unit 21 Unit capacity change amount calculation unit 22 Storage unit 23 Timer 50 Secondary battery unit 51 Cell 52 Voltage sensor 53 Current sensor 100 Battery monitoring device

Claims (8)

A charge amount calculation device that calculates a charge amount of a secondary battery,
A voltage acquisition unit for acquiring a voltage of the secondary battery;
A current acquisition unit that acquires the current of the secondary battery,
A first calculating unit that integrates the current acquired by the current acquiring 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 charge amount difference calculation unit that calculates a charge amount difference between the first charge amount calculated by the first calculation unit and the second charge amount calculated by the second calculation unit;
A condition determination unit that determines whether a predetermined condition is satisfied based on the charge amount difference calculated by the charge amount difference calculation unit;
A correction unit that corrects the first charge amount based on the second charge amount when the condition determination unit determines that the predetermined condition is satisfied ;
A change amount of the charge amount difference is calculated based on the charge amount difference calculated by the charge amount difference calculation unit at each of a first correction time point corrected by the correction unit and a second correction time point before the first correction time point. A change amount calculating unit;
An error amount calculation unit that calculates an error amount based on the change amount calculated by the change amount calculation unit and the charge continuation time or the discharge continuation time after the first correction time point;
With
The condition determination unit includes:
The error amount calculated in the error amount calculation unit based on whether it is greater than the predetermined threshold value, the charge amount calculating device you determine whether to satisfy the predetermined condition. 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 condition determination unit includes:
The charge amount calculation device according to claim 1, wherein it is determined whether or not the predetermined condition is satisfied, based on whether or not switching has been performed by the switching determination unit. A capacity calculation unit that calculates the charged or discharged capacity between the first correction time and the second correction time;
A unit capacity change amount calculation unit that calculates a unit capacity change amount per unit capacity based on the change amount calculated by the change amount calculation unit and the capacity calculated by the capacity calculation unit,
The error amount calculation unit,
The charge amount calculation according to claim 1 , wherein an error amount is calculated based on the unit capacity change amount calculated by the unit capacity change amount calculation unit and the charge capacity or the discharge capacity of the secondary battery after the first correction time. apparatus. The condition determination unit includes:
The charge amount calculation according to claim 1 or 2, wherein it is determined whether the predetermined condition is satisfied based on whether the charge amount difference calculated by the charge amount difference calculation unit is equal to or more than a predetermined value. apparatus. The condition determination unit includes:
If the charge duration or discharge duration after the time corrected by the correction section is longer than a predetermined time, to any one of whether or not to satisfy the predetermined condition from determining claims 1 to 4 A charge amount calculation device according to any one of the preceding claims. 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 5 for calculating a second amount of charge of the secondary battery The charge amount calculation device according to any one of the preceding claims. A computer program for causing a computer to calculate a charge amount of a secondary battery,
On the computer,
Processing to obtain the voltage of the secondary battery;
A process of obtaining the current of the secondary battery;
A process of calculating a first amount of charge of the secondary battery by integrating the obtained current,
A process of calculating a second charge amount of the secondary battery based on the acquired voltage and current and an equivalent circuit model of the secondary battery;
A process of calculating a charge amount difference between the calculated first charge amount and the second charge amount;
A process of determining whether or not a predetermined condition is satisfied based on the calculated charge amount difference;
A process of correcting the first charge amount based on the second charge amount when it is determined that the predetermined condition is satisfied ;
A process of calculating a change amount of the charge amount difference based on the charge amount difference calculated at each of the corrected first correction time point and the second correction time point before the first correction time point;
A process of calculating an error amount based on the calculated change amount and the charge duration or the discharge duration after the first correction time;
A process of determining whether or not the predetermined condition is satisfied, based on whether or not the calculated error amount is equal to or more than a predetermined threshold value;
A computer program that executes 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,
A charge amount difference calculation unit calculates a charge amount difference between the calculated first charge amount and the second charge amount,
The condition determination unit determines whether or not a predetermined condition is satisfied based on the calculated charge amount difference,
When it is determined that the predetermined condition is satisfied, the correction unit corrects the first charge amount based on the second charge amount ,
Calculating a change amount of the charge amount difference based on the charge amount difference calculated at each of the corrected first correction time point and the second correction time point before the first correction time point;
Calculating an error amount based on the calculated change amount and the charge duration or the discharge duration after the first correction time,
The calculated amount of error based on whether a predetermined threshold value or more, the charge amount calculating method for determining whether to satisfy the predetermined condition.

Images