JP6672743B2 - Full charge capacity calculation device, computer program, and full charge capacity calculation method - Google Patents

Description

  The present invention relates to a full charge capacity calculation device for calculating a full charge capacity of a secondary battery mounted on a vehicle, a computer program for realizing the full charge capacity calculation device, and a full charge capacity calculation method.

  In recent years, vehicles such as HEVs (Hybrid Electric Vehicles) and EVs (Electric Vehicles) have become widespread. HEV and EV are equipped with a secondary battery. As the vehicle runs, switching between charging and discharging of the secondary battery is repeated. When the state of charge of the secondary battery greatly fluctuates due to charging and discharging while the vehicle is traveling, the upper limit value of the state of charge (SOC) of the secondary battery, that is, a case where a decrease in the full charge capacity cannot be detected with high accuracy. There is.

  Therefore, the first state of charge before the start of charging of the secondary battery is estimated, the integrated value of the charging current from the start of charging to the completion of charging is calculated, and the second state of charge at the time of completion of charging is calculated. A charging state estimating device that estimates and estimates an upper limit value (full charge capacity) of the charging state of the secondary battery based on the estimated first charging state, the second charging state, and the calculated integrated value is disclosed. (See Patent Document 1).

Japanese Patent No. 4978662

  However, a device such as Patent Literature 1 estimates the upper limit of the state of charge by charging using an external power supply, and thus is applied to a vehicle such as an HEV that repeatedly charges a secondary battery without using an external power supply. Can not do it. In addition, if a method such as that described in Patent Document 1 is applied to a case where charging is performed without using an external power supply, if the charging current fluctuates, a method using only the integrated value can accurately calculate the integrated value of the charging current. Cannot be calculated, and as a result, the state of charge cannot be accurately obtained.

  The present invention has been made in view of such circumstances, and a full charge capacity calculation device capable of accurately calculating a full charge capacity of a secondary battery, and a computer program for realizing the full charge capacity calculation device And a method for calculating a full charge capacity.

A full charge capacity calculation device according to an embodiment of the present invention is a full charge capacity calculation device that calculates a full charge capacity of a secondary battery mounted on a vehicle, and calculates an internal resistance and a discharge capacity of the secondary battery. A storage unit that stores the associated information, an internal resistance calculation unit that calculates an internal resistance based on a voltage and a current before and after switching between charging and discharging of the secondary battery, an internal resistance calculated by the internal resistance calculation unit, A first estimator for estimating a first full charge capacity of the secondary battery based on the related information, and an integrated value calculator for calculating an integrated value of a discharge current over an integrated time when the secondary battery is discharged And a reduction amount calculation unit that calculates the reduction amount of the charging rate of the secondary battery at the integration time, based on the integration value calculated by the integration value calculation unit and the reduction amount calculated by the reduction amount calculation unit. Estimating a second full charge capacity of the secondary battery; And a full charge capacity calculator that calculates a full charge capacity of the secondary battery based on the first full charge capacity estimated by the first estimator and the second full charge capacity estimated by the second estimator. Wherein the full charge capacity calculation unit is configured to determine that a difference between the first full charge capacity estimated by the first estimation unit and the second full charge capacity estimated by the second estimation unit is equal to or smaller than a predetermined difference threshold. , it calculates the full charge capacity of the secondary battery.

A computer program according to an embodiment of the present invention is a computer program for causing a computer to calculate a full charge capacity of a secondary battery mounted on a vehicle, and switches a computer between charge and discharge of the secondary battery. An internal resistance calculating unit that calculates an internal resistance based on the preceding and following voltages and currents; and a first full capacity of the secondary battery based on the related information that associates the internal resistance and the discharge capacity of the secondary battery and the calculated internal resistance. A first estimating unit for estimating a charging capacity, an integrated value calculating unit for calculating an integrated value of a discharge current over an integrated time during discharging of the secondary battery, and a charging rate of the secondary battery at the integrated time A reduction amount calculation unit that calculates the reduction amount of the second battery, a second estimation unit that estimates a second full charge capacity of the secondary battery based on the calculated integrated value and the decrease amount, and a first full charge capacity and a second charge amount that are estimated. 2 full charge Amount to function as a full charge capacity calculation unit for calculating a full charge capacity of the secondary battery based, the full charge capacity calculation section, a difference of the first full charge capacity and the second full charge capacity estimated is given If it is less difference threshold, it calculates the full charge capacity of the secondary battery.

A full charge capacity calculation method according to an embodiment of the present invention is a full charge capacity calculation method for calculating a full charge capacity of a secondary battery mounted on a vehicle, wherein an internal resistance and a discharge capacity of the secondary battery are calculated. The associated information is stored in the storage unit, and the internal resistance calculation unit calculates the internal resistance based on the voltage and the current before and after switching of the charging and discharging of the secondary battery, and based on the calculated internal resistance and the related information. The first estimating unit estimates the first full charge capacity of the secondary battery, and the integrated value calculating unit calculates the integrated value of the discharge current over the integrated time during discharging of the secondary battery. The reduction amount calculation unit calculates the reduction amount of the charging rate of the secondary battery in the above, and the second estimation unit estimates the second full charge capacity of the secondary battery based on the calculated integrated value and the reduction amount. Based on the estimated first full charge capacity and second full charge capacity The full charge capacity calculation unit calculates the full charge capacity of the pond, and when the estimated difference between the first full charge capacity and the second full charge capacity is equal to or less than a predetermined difference threshold, the full charge capacity of the secondary battery is calculated. the full charge capacity calculation unit calculates.

  According to the present invention, it is possible to accurately calculate the full charge capacity of 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 full charge capacity calculation device according to the present embodiment. It is a block diagram showing an example of composition of a battery monitoring device as a full charge capacity calculation device of this embodiment. It is a schematic diagram which shows an example of the change of the electric current of a secondary battery unit when a vehicle stops by signal waiting etc .. FIG. 9 is a schematic diagram illustrating an example of a change in SOC of the secondary battery unit when the vehicle stops at a traffic light or the like. It is a schematic diagram which shows an example of a change of the voltage of the secondary battery unit when the vehicle stops at a traffic light or the like. FIG. 4 is an explanatory diagram illustrating an example of an internal resistance conversion table by the battery monitoring device according to the present embodiment. FIG. 4 is an explanatory diagram showing an example of a correlation between an internal resistance increase rate and a discharge capacity ratio as related information of a secondary battery unit of the battery monitoring device according to the present embodiment. FIG. 4 is an explanatory diagram illustrating an example of a correlation between an open circuit voltage and a charging rate of a secondary battery unit of the battery monitoring device according to the present embodiment. It is a flowchart which shows an example of the processing procedure of the battery monitoring apparatus of this Embodiment. It is a flowchart which shows an example of the processing procedure of the battery monitoring apparatus of this Embodiment. It is a flowchart which shows an example of the processing procedure of the battery monitoring apparatus of this Embodiment.

[Description of Embodiment of the Present Invention]
A full charge capacity calculation device according to an embodiment of the present invention is a full charge capacity calculation device that calculates a full charge capacity of a secondary battery mounted on a vehicle, and calculates an internal resistance and a discharge capacity of the secondary battery. A storage unit that stores the associated information, an internal resistance calculation unit that calculates an internal resistance based on a voltage and a current before and after switching between charging and discharging of the secondary battery, an internal resistance calculated by the internal resistance calculation unit, A first estimator for estimating a first full charge capacity of the secondary battery based on the related information, and an integrated value calculator for calculating an integrated value of a discharge current over an integrated time when the secondary battery is discharged And a reduction amount calculation unit that calculates the reduction amount of the charging rate of the secondary battery at the integration time, based on the integration value calculated by the integration value calculation unit and the reduction amount calculated by the reduction amount calculation unit. Estimating a second full charge capacity of the secondary battery; And a full charge capacity calculator that calculates a full charge capacity of the secondary battery based on the first full charge capacity estimated by the first estimator and the second full charge capacity estimated by the second estimator. And

  A computer program according to an embodiment of the present invention is a computer program for causing a computer to calculate a full charge capacity of a secondary battery mounted on a vehicle, and switches a computer between charge and discharge of the secondary battery. An internal resistance calculating unit that calculates an internal resistance based on the preceding and following voltages and currents; and a first full capacity of the secondary battery based on the related information that associates the internal resistance and the discharge capacity of the secondary battery and the calculated internal resistance. A first estimating unit for estimating a charging capacity, an integrated value calculating unit for calculating an integrated value of a discharge current over an integrated time during discharging of the secondary battery, and a charging rate of the secondary battery at the integrated time A reduction amount calculation unit that calculates the reduction amount of the second battery, a second estimation unit that estimates a second full charge capacity of the secondary battery based on the calculated integrated value and the decrease amount, and a first full charge capacity and a second charge amount that are estimated. 2 full charge Function as full charge capacity calculation unit for calculating a full charge capacity of the secondary battery based on the amount.

  A full charge capacity calculation method according to an embodiment of the present invention is a full charge capacity calculation method for calculating a full charge capacity of a secondary battery mounted on a vehicle, wherein an internal resistance and a discharge capacity of the secondary battery are calculated. The associated information is stored in the storage unit, and the internal resistance calculation unit calculates the internal resistance based on the voltage and the current before and after switching of the charging and discharging of the secondary battery, and based on the calculated internal resistance and the related information. The first estimating unit estimates the first full charge capacity of the secondary battery, and the integrated value calculating unit calculates the integrated value of the discharge current over the integrated time during discharging of the secondary battery. The reduction amount calculation unit calculates the reduction amount of the charging rate of the secondary battery in the above, and the second estimation unit estimates the second full charge capacity of the secondary battery based on the calculated integrated value and the reduction amount. Based on the estimated first full charge capacity and second full charge capacity Full charge capacity calculation unit the full charge capacity of the pond is calculated.

  The storage unit stores related information relating the internal resistance and the discharge capacity of the secondary battery. The related information relates the internal resistance of the secondary battery to the discharge capacity, and the internal resistance may be represented by an absolute value, or by an internal resistance increase rate with respect to the internal resistance of a new secondary battery. Is also good. The discharge capacity is a capacity that the secondary battery can discharge, and corresponds to a full charge capacity. The discharge capacity may be represented by an absolute value, or may be represented by a ratio to the discharge capacity of a new secondary battery. It should be noted that storing the related information includes storing the related information in a format such as a table, or obtaining the association in a format such as an arithmetic expression.

  The internal resistance calculation unit calculates the internal resistance based on the voltage and the current before and after the switching between charging and discharging of the secondary battery. The absolute value of the slope of the straight line obtained from the voltage and current between the two points before and after the switching between charge and discharge indicates the internal resistance of the secondary battery. For example, assuming that the voltage before switching between charging and discharging of the secondary battery is Vb, the current is Ib, the voltage after switching between charging and discharging of the secondary battery is Vc, and the current is Ic, the internal resistance R is R = It can be calculated by the formula (Vc−Vb) / (Ic−Ib).

  The first estimator estimates the first full charge capacity C1 of the secondary battery based on the internal resistance calculated by the internal resistance calculator and the related information. That is, the discharge capacity corresponding to the calculated internal resistance can be determined as the first full charge capacity C1 with reference to the related information stored in the storage unit.

  The integrated value calculation unit calculates the integrated value of the discharge current over the integrated time when the secondary battery is discharged. That is, the integrated value is calculated by integrating the discharge current sampled at a predetermined sampling period from the start time to the end time of the integration time.

  The reduction amount calculation unit calculates the reduction amount of the charging rate of the secondary battery during the integration time. The charging rate is an SOC (State of Charge). The SOC can be represented by a ratio of the remaining amount to the full charge capacity. Assuming that the charging rate at the start time ta of the integration time is SOC (ta) and the charging rate at the end time tb of the integration time is SOC (tb), the amount of decrease is represented by SOC (ta) -SOC (tb). be able to.

  The second estimator estimates the second full charge capacity C2 of the secondary battery based on the integrated value calculated by the integrated value calculator and the decrease calculated by the decrease calculator. For example, assuming that the integrated value of the discharge current is ΔI and the amount of decrease is SOC (ta) −SOC (tb), the second full charge capacity C2 is C2 = {I / {SOC (ta) −SOC (tb)}. Can be estimated.

  The full charge capacity calculator calculates the full charge capacity C of the secondary battery based on the first full charge capacity C1 estimated by the first estimator and the second full charge capacity C2 estimated by the second estimator. For example, an average value of the first full charge capacity C1 and the second full charge capacity C2 is calculated, and the calculated average value can be used as the full charge capacity C.

  With the configuration described above, the restriction of performing charging with an external power supply is not required. Further, the first full charge capacity C1 and the second full charge capacity C2 are estimated based on two different methods (a method using an internal resistance and a method using an integrated value of a discharge current), and the full charge capacity of the secondary battery is estimated. Since C is calculated, the reliability can be improved as compared with the case where only one method is used, and the full charge capacity of the secondary battery can be calculated with high accuracy.

  In the full charge capacity calculation device according to an embodiment of the present invention, the full charge capacity calculation unit includes a first full charge capacity estimated by the first estimation unit and a second full charge capacity estimated by the second estimation unit. If the difference is equal to or smaller than a predetermined difference threshold, the full charge capacity of the secondary battery is calculated.

  When the difference between the first full charge capacity calculated by the first calculation unit and the second full charge capacity calculated by the second calculation unit is equal to or smaller than a predetermined difference threshold, the full charge capacity calculation unit calculates the full charge of the secondary battery. Calculate the capacity. If the difference between the first full charge capacity and the second full charge capacity exceeds a predetermined difference threshold, it is considered that the reliability of at least one of the first full charge capacity and the second full charge capacity is not high. Therefore, when the difference between the first full charge capacity and the second full charge capacity is equal to or smaller than a predetermined difference threshold, the accuracy of the calculated value of the full charge capacity is further improved by calculating the full charge capacity of the secondary battery. Can be.

  A full charge capacity calculation device according to an embodiment of the present invention includes an acquisition unit that acquires a stop time of the vehicle, and a determination unit that determines whether discharge of the secondary battery is started based on the stop of the vehicle. The internal resistance calculator, the first estimator, the integrated value calculator, the decrease calculator, the second estimator, and the full charge capacity calculator are configured to discharge the secondary battery by the determination unit. When it is determined that there is, and the stop time acquired by the acquisition unit is longer than the integration time, each process is performed.

  The acquisition unit acquires a stop time of the vehicle. The stop time of the vehicle can be acquired from, for example, an in-vehicle device that calculates the stop time or an external roadside device. The stop time Ts of the vehicle is calculated using, for example, signal information of an intersection downstream of the vehicle (for example, a green signal start time tg), a distance L to the intersection, and a speed V of a starting wave after the start of the green signal. = (T-tg) + L / V. Here, t is the current time, and it is assumed that the current time t is temporally later than the green signal start time tg.

  The determination unit determines whether or not the discharge of the secondary battery is started based on the stop of the vehicle. That is, the determination unit determines whether the idling stop is started by stopping the vehicle and the discharge of the secondary battery is started.

  When the determination unit determines that the secondary battery is discharged and the stop time acquired by the acquisition unit is longer than the integration time, the internal resistance calculation unit, the first estimation unit, the integration value calculation unit, the decrease amount calculation unit, the second estimation The unit and the full charge capacity calculation unit perform respective processes. That is, when the vehicle stops longer than the integration time for calculating the integrated value of the discharge current, each process related to the calculation of the full charge capacity is performed. If the stop time of the vehicle is shorter than the integrated time for calculating the integrated value of the discharge current, the processes related to the calculation of the full charge capacity are not performed. Accordingly, it is possible to determine in advance whether the full charge capacity calculation (especially, the second full charge capacity estimation) can be performed while the vehicle is stopped, and thus it is possible to prevent a useless processing load from occurring.

  The full charge capacity calculation device according to the embodiment of the present invention, when the determination unit determines that there is discharge of the secondary battery, the charging rate of the secondary battery from the discharge start time of the secondary battery is a predetermined A descent time calculation unit that calculates a descent time until the descent time to the lower limit value, the internal resistance calculation unit, the first estimation unit, the integrated value calculation unit, the decrease amount calculation unit, the second estimation unit, The full charge capacity calculation unit performs each process when the stop time of the vehicle is longer than the descent time.

  The fall time calculation unit, when the determination unit determines that the secondary battery is discharged, calculates a fall time from the time when the discharge of the secondary battery starts to the time when the charge rate of the secondary battery falls to a predetermined lower limit. . When the SOC of the secondary battery reaches the lower limit, the secondary battery switches from a discharged state to a charged state. That is, the internal resistance of the secondary battery can be calculated by sampling and acquiring the voltage and current before and after switching from discharging to charging.

  When the stop time of the vehicle is longer than the descent time, the internal resistance calculator, the first estimator, the integrated value calculator, the decrease amount calculator, the second estimator, and the full charge capacity calculator perform respective processes. That is, when switching between charging and discharging is performed while the vehicle is stopped, each process related to the calculation of the full charge capacity is performed. Further, when the switching of charge and discharge is not performed while the vehicle is stopped, each process related to the calculation of the full charge capacity is not performed. Accordingly, it is possible to determine in advance whether or not the switching of charge and discharge for calculating the internal resistance (especially, the first full charge capacity estimation) is performed while the vehicle is stopped, so that a useless processing load is generated. Can be prevented.

  The full charge capacity calculation device according to the embodiment of the present invention, when the determination unit determines that there is discharge of the secondary battery, the time when a predetermined elapsed time has elapsed from the discharge start time of the secondary battery, A start time specifying unit that specifies the start time of the integration time is provided.

  When the determination unit determines that the discharge of the secondary battery is present, the start time specification unit specifies a time when a predetermined elapsed time has elapsed from the start of discharge of the secondary battery as a start time of the integration time. Immediately after the start of the discharge (for example, about several seconds), the voltage of the secondary battery fluctuates and becomes unstable. When calculating the state of charge (SOC) at the start of the integration time of the secondary battery, it is necessary to obtain the OCV (open circuit voltage, open circuit voltage) at the start of the integration time. By providing an elapsed time until the voltage of the secondary battery is stabilized, the OCV at the start of the integration time can be accurately obtained, and as a result, the charging rate (SOC) and the second full charge capacity can be accurately determined. It can be calculated, and the reliability of the calculation of the full charge capacity can be improved.

  The full charge capacity calculation device according to the embodiment of the present invention, when the determination unit determines that there is discharge of the secondary battery, before the time when the charging rate of the secondary battery drops to a predetermined lower limit value An end time specifying unit for specifying a time point as the end time of the integration time is provided.

  When the determination unit determines that the secondary battery is discharged, the end time specifying unit specifies a time point before the time point at which the charging rate of the secondary battery drops to a predetermined lower limit as the end time point of the integration time. The time point before the time point of falling to the predetermined lower limit value may be, for example, a time point one second before the time point of falling, but is not limited to one second. Thus, the discharge current can be integrated until immediately before the charging rate of the secondary battery drops to the predetermined lower limit and the mode is switched from discharging to charging. If the time for integrating the discharge current can be lengthened, the calculated integrated value increases, and the integrated value with respect to the amount of decrease in the charging rate when calculating the second full charge capacity can be increased and calculated. The error of the second full charge capacity can be reduced.

  The full charge capacity calculation device according to the embodiment of the present invention assigns a first weighting factor to the first full charge capacity estimated by the first estimating unit, and provides the second full charge estimated by the second estimating unit. There is provided a weighting unit for giving a second weighting coefficient to the capacity, and the full charge capacity calculation unit calculates a full charge capacity of the secondary battery by giving a weighting coefficient by the weighting unit.

  The weighting unit assigns a first weighting coefficient to the first full charge capacity estimated by the first estimation unit, and assigns a second weighting coefficient to the second full charge capacity estimated by the second estimation unit. The full charge capacity calculation unit calculates the full charge capacity of the secondary battery by assigning a weighting coefficient by the weighting unit.

  For example, the first weighting coefficient for the first full charge capacity C1 is α1, and the first weighting coefficient for the second full charge capacity C2 is α2. Here, it is assumed that α1 + α2 = 1. The full charge capacity C of the secondary battery can be calculated, for example, as C = C1 × α1 + C2 × α2. Thereby, a higher weighting coefficient is assigned to the higher reliability, and a highly reliable full charge capacity can be calculated as a whole.

  A full charge capacity calculation device according to an embodiment of the present invention includes a current difference calculation unit that calculates a difference between currents before and after switching between charging and discharging of the secondary battery, and the weighting unit includes a current difference calculation unit. If the calculated current difference is greater than or equal to a predetermined current threshold, the first weighting factor is made larger than the second weighting factor.

  The current difference calculation unit calculates a difference between currents before and after switching between charging and discharging of the secondary battery. For example, assuming that the current before switching between charging and discharging of the secondary battery is Ib and the current after switching between charging and discharging of the secondary battery is Ic, the difference between the currents can be calculated by (Ic−Ib).

  The weighting unit sets the first weighting factor to be larger than the second weighting factor when the current difference calculated by the current difference calculating unit is equal to or greater than a predetermined current threshold. When the current difference (Ic-Ib) is equal to or greater than the predetermined current threshold, the calculation accuracy of the internal resistance is improved, and the reliability of the first full charge capacity is increased. Therefore, by making the first weighting coefficient corresponding to the first full charge capacity larger than the second weighting coefficient, a highly reliable full charge capacity can be calculated as a whole.

  In the full charge capacity calculation device according to the embodiment of the present invention, the weighting unit may set the second weighting coefficient to the first integration value when the integrated value calculated by the integrated value calculation unit is equal to or greater than a predetermined integration threshold. Larger than the weighting coefficient of.

  The weighting unit sets the second weighting factor larger than the first weighting factor when the integrated value calculated by the integrated value calculation unit is equal to or greater than a predetermined integration threshold. When the integrated value is equal to or larger than the predetermined integrated threshold, the integrated value with respect to the amount of decrease in the charging rate when calculating the second full charge capacity can be increased, and the reliability of the second full charge capacity increases. Therefore, by making the second weighting coefficient corresponding to the second full charge capacity larger than the first weighting coefficient, it is possible to calculate the full charge capacity with high reliability as a whole.

[Details of the embodiment of the present invention]
Hereinafter, an embodiment of an internal resistance 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 full charge capacity 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, 62, 63, a generator (ALT) 71, a starter motor (ST) 72, a battery 73, and an electric load. 74, 75 and the like.

  The secondary battery unit 50 is, for example, a lithium ion battery, and has a plurality of cells 51 connected in series or series / parallel. The secondary battery unit 50 includes a voltage sensor 52, a current sensor 53, and a temperature sensor 54. The voltage sensor 52 detects the voltage between both ends of the secondary battery unit 50 and the voltage of each cell 51, 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 73 is, for example, a lead battery, supplies power to an electric load 74 (for example, lights, various motors, various controllers, etc.) of the vehicle, and drives the starter motor 72 when the relay 63 is turned on. Power supply for power supply. The generator 71 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 73. When the relays 61 and 62 are on, the generator 71 charges the battery 73 and the secondary battery unit 50. When the relay 61 is turned on, the secondary battery unit 50 supplies electric power to an electric load 75 (for example, an engine system electrical device, audio, or the like). The relays 61, 62, and 63 are turned on and off by a relay control unit (not shown) in order to distribute power to be supplied according to the charge / discharge balance of the battery 73 and the secondary battery unit 50 and the degree of load.

  FIG. 2 is a block diagram illustrating an example of a configuration of a battery monitoring device 100 as a full charge capacity calculation device 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 temperature acquisition unit 13, a switch determination unit 14, a standby time identification unit 15, a resistance calculation unit 16, and a current integrated value calculation. Unit 17, charging rate calculating unit 18, first estimating unit 19, second estimating unit 20, stop information obtaining unit 21, open circuit voltage calculating unit 22, full charge capacity calculating unit 23, descent time calculating unit 24, specifying unit 25, A weighting unit 26, a current difference calculation unit 27, a storage unit 28, a timer 29 for clocking, and the like are provided.

  The control unit 10 includes a CPU and the like.

  The voltage acquisition unit 11 acquires the voltage of the secondary battery unit 50 (the voltage across the secondary battery unit 50 and the voltage of each cell 51). Further, the current acquisition unit 12 acquires the current (charge current and discharge current) of the secondary battery unit 50.

  More specifically, the current acquisition unit 12 includes an AD converter, converts the acquired current into a digital value at a predetermined sampling cycle, and outputs the converted digital value to the control unit 10. The sampling period can be, for example, 10 ms, but is not limited to this. The control unit 10 can read the current value of the secondary battery unit 50 at a predetermined sampling cycle.

  The voltage acquisition unit 11 includes an AD converter, converts the acquired voltage into a digital value at a predetermined sampling cycle, and outputs the converted digital value to the control unit 10. The control unit 10 can read the voltage value of the secondary battery unit 50 at a predetermined sampling cycle.

  The temperature acquisition unit 13 acquires the temperature of the secondary battery unit 50. More specifically, the temperature acquisition unit 13 includes an AD converter, converts the acquired temperature into a digital value at a predetermined sampling cycle, and outputs the converted digital value to the control unit 10. The control unit 10 can read the temperature of the secondary battery unit 50 at a predetermined sampling cycle.

  The switching determination unit 14 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, if the current acquired by the current acquisition unit 12 in the case of charging is defined as positive, the direction of the current is opposite between charging and discharging, so if the current acquired by the current acquisition unit 12 is negative, It can be determined that the discharge occurs. That is, one of charge or discharge is defined as positive and the current changes from positive to negative or 0, the current changes from 0 to positive or negative, or the current changes from negative to positive or 0 , It can be determined that there is switching between charging and discharging.

  The standby time specifying unit 15 specifies the standby time based on a boundary frequency range in which the diffusion impedance caused by a predetermined ion diffusion process contributes to the impedance of the secondary battery unit 50 in the impedance spectrum of the secondary battery unit 50. I do. The impedance spectrum, also called a Cole-Cole plot or a Nyquist plot, is a plot of values obtained by measuring the impedance of the secondary battery unit 50 at a plurality of frequencies using the AC impedance method. The predetermined ion is a lithium (Li) ion. The boundary frequency band means that a frequency has a required width, and it is not limited to a single frequency.

  The secondary battery unit 50 can be represented by an equivalent circuit including the resistance Rs of the electrolyte bulk, the interface charge transfer resistance Rc, the electric double layer capacitance C, and the diffusion impedance Zw. The internal resistance of the secondary battery unit 50 is mainly composed of the resistance Rs of the electrolytic solution bulk and the interface charge transfer resistance Rc. On the other hand, in the impedance spectrum obtained by plotting values obtained by measuring the impedance of the secondary battery unit 50 at a plurality of frequencies using the AC impedance method, when the frequency is changed from a high frequency to a low frequency, in the above-described boundary frequency range, The diffusion impedance Zw increases, and the impedance of the secondary battery unit 50 increases. Then, the waiting time Tw can be obtained based on the boundary frequency range where the diffusion impedance Zw increases. The waiting time Tw can be, for example, 100 ms, but is not limited to this.

  There is a relationship of Tw = 1 / (2 × f) between the frequency f in the AC impedance method and the standby time Tw from when the direct current is supplied to when the measurement is performed. That is, the waiting time Tw can be specified from, for example, the relationship of the reciprocal of twice the frequency f. For example, when the frequency f is 5 Hz, the standby time Tw is 0.1 seconds. It should be noted that the standby time Tw is set as a reciprocal of twice the frequency f, for example. For example, the standby time Tw may be set as a reciprocal four times the frequency f.

  The resistance calculation unit 16 has a function as an internal resistance calculation unit, and calculates the internal resistance based on the voltage and the current before and after switching between charging and discharging of the secondary battery unit 50. The absolute value of the slope of the straight line obtained from the voltage and current between the two points before and after switching between charging and discharging indicates the internal resistance of the secondary battery unit 50. For example, assuming that the voltage before switching between the charging and discharging of the secondary battery unit 50 is Vb, the current is Ib, the voltage after switching of the charging and discharging of the secondary battery unit 50 is Vc, and the current is Ic, the internal resistance R Can be calculated by the formula of R = (Vc−Vb) / (Ic−Ib).

  More specifically, the resistance calculation unit 16 calculates the voltage Vb and the current Ib obtained before the charging / discharging switching time of the secondary battery unit 50, and a predetermined standby time from the charging / discharging switching time of the secondary battery unit 50. The internal resistance R of the secondary battery unit 50 is calculated based on the voltage Vc and the current Ic acquired after Tw (for example, 100 ms) has elapsed.

  The storage unit 28 stores related information in which the internal resistance and the discharge capacity of the secondary battery unit 50 are associated. The related information relates the internal resistance and the discharge capacity of the secondary battery unit 50, and the internal resistance may be represented by an absolute value, or the internal resistance may be increased with respect to the internal resistance of a new secondary battery unit 50. It may be represented by a rate. The discharge capacity is a capacity that the secondary battery unit 50 can discharge, and corresponds to a full charge capacity. The discharge capacity may be represented by an absolute value, or may be represented by a ratio to the discharge capacity of a new secondary battery unit 50. It should be noted that storing the related information includes storing the related information in a format such as a table, or obtaining the association in a format such as an arithmetic expression. Specific examples of the related information will be described later.

  The first estimator 19 estimates the first full charge capacity C1 of the secondary battery unit 50 based on the internal resistance R calculated by the resistance calculator 16 and the related information. That is, with reference to the related information stored in the storage unit 28, the discharge capacity corresponding to the calculated internal resistance R can be obtained as the first full charge capacity C1.

  The current integrated value calculating unit 17 has a function as an integrated value calculating unit, and calculates the integrated value of the discharge current over the integrated time when the secondary battery unit 50 discharges. That is, the integrated value is calculated by integrating the discharge current sampled at a predetermined sampling period from the start time to the end time of the integration time.

  The charging rate calculator 18 calculates the charging rate of the secondary battery unit 50. The charging rate is an SOC (State of Charge). The SOC can be represented by a ratio of the remaining amount to the full charge capacity. In addition, the charging rate calculation unit 18 has a function as a reduction amount calculation unit, and calculates the reduction amount of the charging rate of the secondary battery unit 50 during the integration time. For example, assuming that the charging rate at the start time ta of the integration time is SOC (ta) and the charging rate at the end time tb of the integration time is SOC (tb), the decrease amount is SOC (ta) −SOC (tb). Can be represented by

  The second estimating unit 20 estimates the second full charge capacity C2 of the secondary battery unit 50 based on the integrated value calculated by the current integrated value calculating unit 17 and the reduction amount calculated by the charging rate calculating unit 18. For example, assuming that the integrated value of the discharge current is ΔI and the amount of decrease is SOC (ta) −SOC (tb), the second full charge capacity C2 is C2 = {I / {SOC (ta) −SOC (tb)}. Can be estimated.

  The full charge capacity calculator 23 calculates the full charge capacity C of the secondary battery unit 50 based on the first full charge capacity C1 estimated by the first estimator 19 and the second full charge capacity C2 estimated by the second estimator 20. Is calculated. For example, an average value of the first full charge capacity C1 and the second full charge capacity C2 is calculated, and the calculated average value can be used as the full charge capacity C.

  With the above-described configuration, when calculating the full charge capacity, there is no need to limit charging with an external power supply. Further, the first full charge capacity C1 and the second full charge capacity C2 are estimated based on two different methods (a method using the internal resistance and a method using the integrated value of the discharge current), and the full charge of the secondary battery unit 50 is estimated. Since the charge capacity C is calculated, the reliability can be improved as compared with the case where only one type of technique is used, and the full charge capacity of the secondary battery unit 50 can be calculated with high accuracy.

  When the difference between the first full charge capacity estimated by the first estimator 19 and the second full charge capacity estimated by the second estimator 20 is equal to or smaller than a predetermined difference threshold, The full charge capacity of the next battery unit 50 is calculated. The difference threshold can be, for example, a capacity corresponding to 3% of the initial full charge capacity when the secondary battery unit 50 is new, but is not limited to this.

  If the difference between the first full charge capacity and the second full charge capacity exceeds a predetermined difference threshold, it is considered that the reliability of at least one of the first full charge capacity and the second full charge capacity is not high. Therefore, when the difference between the first full charge capacity and the second full charge capacity is equal to or less than a predetermined difference threshold, the accuracy of the calculated value of the full charge capacity is further improved by calculating the full charge capacity of the secondary battery unit 50. Can be enhanced.

  Next, a method of calculating the full charge capacity of the secondary battery unit 50 by the battery monitoring device 100 according to the present embodiment will be described in detail.

  FIG. 3 is a schematic diagram showing an example of a change in the current of the secondary battery unit 50 when the vehicle stops at a traffic light or the like, and FIG. 4 shows a diagram of the secondary battery unit 50 when the vehicle stops at a traffic light or the like. FIG. 5 is a schematic diagram illustrating an example of a change in the SOC, and FIG. 5 is a schematic diagram illustrating an example of a change in the voltage of the secondary battery unit 50 when the vehicle stops at a traffic light or the like.

  In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates current. When the current is positive, the charging current is indicated, and when the current is negative, the discharging current is indicated. Further, the current values at the respective time points t1 to t5 are represented by I (t1) to I (t5). In FIG. 3, a time point t1 indicates a time point when the vehicle stops, and when the idling stop is started, the discharge of the secondary battery unit 50 is started. The time point t2 is a time point when the voltage stabilization waiting time (predetermined elapsed time) elapses from the time point t1. That is, (t2−t1) represents a voltage stabilization wait time as a predetermined elapsed time. Time point t4 indicates a time point when the SOC of the secondary battery unit 50 has decreased to the lower limit, and at time point t4, the secondary battery unit 50 switches from the discharged state to the charged state. The time point t3 is a time point that is a predetermined time before the time point t4, and the predetermined time can be, for example, one second, but is not limited to this. Time point t5 is a time point at which the vehicle starts running, the charging of the secondary battery unit 50 ends, and the state shifts from the charged state to the state without charge / discharge.

  That is, the stop time of the vehicle is the time from time t1 to time t5. The voltage stabilization waiting time as the predetermined elapsed time is a time from time t1 to time t2. The integration time is a time from time t2 to time t3. That is, the start time of the integration time is t2 and the end time is t3. The falling time is a time from time t1 to time t4.

  In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates SOC. In FIG. 4, the SOC is schematically shown. The SOC (t) at the time point t is calculated by dividing the integrated current value at the time point t calculated by the integrated current value calculation unit 17 by the full charge capacity at the time point t. Also, the SOC at each time point t1 to t5 is represented by SOC (t1) to SOC (t5). In the example of FIG. 4, when the vehicle stops at the time point t1, the idling stop is started and the discharge of the secondary battery unit 50 is started, so that the SOC gradually starts to decrease. Time point t4 is a time point when the SOC reaches the lower limit value, and switches from discharging to charging. After time t4, the SOC starts to increase. At time point t5, the vehicle starts running and changes from a charged state to a state without charge / discharge, so that the SOC maintains a substantially constant value. Since the load operating while the vehicle is stopped is determined, the discharge current after time t1 is known in advance. Thus, if SOC (t1) is known, time point t4 at which the SOC reaches the lower limit can be predicted.

  In FIG. 5, the horizontal axis represents time, and the vertical axis represents voltage. Further, the voltage values at the respective time points t1 to t5 are represented by V (t1) to V (t5). When switching from the state without charge / discharge to the discharge state at time t1, the voltage changes immediately after the switching time, and an unstable time zone (for example, about several seconds) occurs. However, after the elapse of the voltage stabilization wait time (time t2), the voltage of the secondary battery unit 50 is stable.

  In the examples shown in FIGS. 3 to 5, how the full charge capacity of the secondary battery unit 50 is calculated will be described below. First, a method of estimating the first full charge capacity C1 will be described.

  First, the resistance calculator 16 uses the voltage and current sampled immediately before the time point t4 as the voltage Vb and the current Ib obtained before the switching point of the charging and discharging of the secondary battery unit 50. Then, the resistance calculation unit 16 determines the voltage Vc and the current Ic obtained after the lapse of a predetermined standby time Tw (for example, 100 ms) from the switching point of the charging and discharging of the secondary battery unit 50 at the time when the standby time Tw has elapsed from the time t4. Use the voltage and current sampled in step 2. As described above, the internal resistance R can be calculated by the equation R = (Vc−Vb) / (Ic−Ib).

  In the above-described example, the resistance calculating unit 16 calculates the internal resistance R based on the voltage and the current before and after the switching time t4 from the discharge to the charging. However, the calculation timing of the internal resistance R is calculated at the time t4. It is not limited to before and after. For example, when there is an opportunity to calculate and store the internal resistance R before the time point t1 at which the vehicle stops, the internal resistance R obtained at that opportunity may be used. However, by calculating the internal resistance R using the voltage and current before and after the time point t4, it is possible to make the estimation timing of the first full charge capacity C1 and the estimation timing of the second full charge capacity C2 close to the calculation timing of the internal resistance. Therefore, the estimation accuracy can be improved.

  Further, the resistance calculator 16 converts the calculated internal resistance R into an internal resistance reference value Rz under the reference condition.

  FIG. 6 is an explanatory diagram illustrating an example of an internal resistance conversion table by the battery monitoring device 100 according to the present embodiment. FIG. 6 shows the case where the SOC is 50% and the temperature is 25 ° C. as a reference condition, and based on the SOC and the temperature when the internal resistance R is calculated, the internal resistance R is converted into an internal resistance reference value Rz under the reference condition. It is for conversion. In FIG. 6, only the main numerical values are shown for simplicity. By dividing the calculated internal resistance by the numerical value in FIG. 6, it can be converted to the internal resistance reference value Rz. For example, dividing the internal resistance R calculated at a temperature of 10 ° C. and an SOC of 90% by 1.5 gives an internal resistance reference value Rz.

  FIG. 7 is an explanatory diagram showing an example of a correlation between the internal resistance increase rate and the discharge capacity ratio as related information of the secondary battery unit 50 of the battery monitoring device 100 according to the present embodiment. In FIG. 7, the horizontal axis indicates the internal resistance increase rate, and the vertical axis indicates the discharge capacity ratio. The temperature is 25 ° C. and the charging rate is 50%. In FIG. 7, the absolute value of the internal resistance may be used instead of the internal resistance increase rate, and the absolute value of the discharge capacity may be used instead of the discharge capacity ratio. As shown in FIG. 7, the discharge capacity ratio decreases as the internal resistance increase rate of the secondary battery unit 50 increases. The correlation between the internal resistance increase rate and the discharge capacity ratio illustrated in FIG. 7 may be stored in the storage unit 28, or may be calculated by a calculation circuit.

  The resistance calculator 16 can calculate the internal resistance increase rate from the calculated internal resistance reference value Rz and the new internal resistance value of the secondary battery unit 50. The first estimating unit 19 can obtain the discharge capacity ratio corresponding to the internal resistance increase rate calculated by the resistance calculating unit 16 by referring to the related information as shown in FIG. The discharge capacity is a capacity that can be discharged from a full charge, and can have the same value as the full charge capacity. As a result, the discharge capacity corresponding to the calculated internal resistance R (more specifically, the internal resistance reference value Rz) can be estimated as the first full charge capacity C1.

  Next, a method of estimating the second full charge capacity C2 will be described.

  The current integrated value calculation unit 17 calculates the integrated value ΔI of the discharge current by integrating the discharge current sampled at a predetermined sampling period from the start time t2 of the integration time to the end time t3.

  The open-circuit voltage calculator 22 calculates the open-circuit voltage (OCV) of the secondary battery unit 50 at each of the start time t2 and the end time t3 of the integration time. For example, the OCV (t2) at the start time t2 can be calculated by the formula OCV (t2) = V (t2) -I (t2) × R, and the OCV (t3) at the end time t3 is OCV (t3). ) = V (t3) −I (t3) × R. Here, R is the internal resistance calculated by the resistance calculator 16.

  As described above, when the open-circuit voltage calculation unit 22 calculates the open-circuit voltage, the internal resistance R calculated by the resistance calculation unit 16 is used. The internal resistance R can be shared with the internal resistance R used when estimating the first full charge capacity C1. Thus, the change in the internal resistance R depending on the temperature or the SOC is small, and the calculation accuracy can be improved. Further, the amount of arithmetic processing can be reduced, and the processing load on the arithmetic processing unit can be reduced.

  FIG. 8 is an explanatory diagram illustrating an example of a correlation between the open circuit voltage and the charging rate of the secondary battery unit 50 of the battery monitoring device 100 according to the present embodiment. In FIG. 8, the horizontal axis indicates the open circuit voltage (OCV), and the vertical axis indicates the state of charge (SOC). FIG. 8 shows a straight line in the graph for simplicity. As shown in FIG. 8, the charging rate increases as the open circuit voltage of the secondary battery unit 50 increases. The correlation between the open-circuit voltage and the charging rate illustrated in FIG. 8 may be stored in the storage unit 28, or may be calculated by a calculation circuit.

  The charging rate calculation unit 18 calculates the SOC based on the OCV calculated by the open voltage calculation unit 22 with reference to the correlation between the open voltage and the charging rate illustrated in FIG. The SOCs of the secondary battery units 50 at the start time t2 and the end time t3 of the integration time are SOC (t2) and SOC (t3), respectively.

  The second estimator 20 estimates the second full charge capacity C2 of the secondary battery unit 50 based on the integrated value calculated by the current integrated value calculator 17 and the SOC decrease calculated by the charge rate calculator 18. For example, assuming that the integrated value of the discharge current is ΔI and the decrease amount is SOC (t2) −SOC (t3), the second full charge capacity C2 is C2 = {I / {SOC (t2) −SOC (t3)}. Can be estimated. For example, assuming that SOC (t2) is 30% and SOC (t3) is 20%, {SOC (t2) -SOC (t3)} = 10%, so the second full charge capacity C2 is an integrated value. ΔI may be multiplied by 10.

  The stop information acquisition unit 21 has a function as an acquisition unit, and acquires a stop time of the vehicle. The stop information acquisition unit 21 has a communication function with an unillustrated in-vehicle device, and acquires a stop time acquired from an in-vehicle device that calculates a stop time. The stop information acquisition unit 21 has a communication function with a roadside device (not shown), and can acquire the stoptime from an external roadside device that calculates a stop time.

  The stop time Ts of the vehicle is calculated using, for example, signal information of an intersection downstream of the vehicle (for example, a green signal start time tg), a distance L to the intersection, and a speed V of a starting wave after the start of the green signal. = (T-tg) + L / V. Here, t is the current time, and it is assumed that the current time t is temporally later than the green signal start time tg.

  The switching determination unit 14 has a function as a determination unit, and determines whether or not the discharge of the secondary battery unit 50 is started based on the stop of the vehicle. That is, the switching determination unit 14 determines whether the idling stop is started by stopping the vehicle and the discharge of the secondary battery unit 50 is started.

  The switching determination unit 14 determines that the secondary battery unit 50 is discharged, and the stop time (the time from the time point t1 to the time point t5 in the examples of FIGS. 3 to 5) acquired by the stop information acquisition unit 21 is the integrated time ( In the examples of FIGS. 3 to 5, when the time is longer than the time from time t2 to time t3), the resistance calculator 16, the first estimator 19, the current integrated value calculator 17, the charge rate calculator 18, and the second estimator 20 and the full charge capacity calculation unit 23 perform respective processes. That is, when the stop time of the vehicle is longer than the integrated time for calculating the integrated value of the discharge current, each process related to the calculation of the full charge capacity is performed. If the stop time of the vehicle is shorter than the integrated time for calculating the integrated value of the discharge current, the processes related to the calculation of the full charge capacity are not performed. This makes it possible to determine in advance whether the full charge capacity calculation (especially the second full charge capacity calculation) can be performed while the vehicle is stopped, so that it is possible to prevent unnecessary processing load from being generated.

  When the stop time of the vehicle is shorter than the integrated time for calculating the integrated value of the discharge current, the resistance calculating unit 16, the first estimating unit 19, the current integrated value calculating unit 17, the charging rate calculating unit 18, Instead of the configuration in which all the processes of the 2 estimation unit 20 and the full charge capacity calculation unit 23 are not performed, it is also possible to not perform some processes.

  When the switching determination unit 14 determines that the secondary battery unit 50 is discharged, the fall time calculation unit 24 reduces the charge rate of the secondary battery unit 50 to a predetermined lower limit from the time when the secondary battery unit 50 starts discharging. The descending time until the time point (in the examples of FIGS. 3 to 5, the time from the time point t1 to the time point t4) is calculated. When the SOC of the secondary battery unit 50 reaches the lower limit, the secondary battery unit 50 switches from the discharged state to the charged state. That is, the internal resistance of the secondary battery unit 50 can be calculated by sampling and acquiring the voltage and current before and after switching from discharging to charging.

  When the stop time of the vehicle is longer than the descent time, the resistance calculator 16, the first estimator 19, the current integrated value calculator 17, the charging rate calculator 18, the second estimator 20, and the full charge capacity calculator 23 respectively Is performed. That is, when switching between charging and discharging is performed while the vehicle is stopped, each process related to the calculation of the full charge capacity is performed. Further, when the switching of charge and discharge is not performed while the vehicle is stopped, each process related to the calculation of the full charge capacity is not performed. Thereby, it is possible to determine in advance whether or not the switching of charge and discharge for calculating the internal resistance (particularly, calculation of the first full charge capacity) is performed while the vehicle is stopped, so that a useless processing load is generated. Can be prevented.

  In addition, when the charge / discharge switching is not performed while the vehicle is stopped, the resistance calculator 16, the first estimator 19, the current integrated value calculator 17, the charge rate calculator 18, the second estimator 20, and the full charge Instead of the configuration in which all the processes of the capacity calculation unit 23 are not performed, it is also possible to prevent some processes from being performed.

  The specifying unit 25 has a function as a start time specifying unit. When the switching determination unit 14 determines that the secondary battery unit 50 is discharged, a predetermined elapsed time from the discharge start time of the secondary battery unit 50 (FIG. In the examples of FIGS. 3 to 5, the time when the time from the time t <b> 1 to the time t <b> 2) has elapsed is specified as the start time of the integration time.

  Immediately after the start of discharging (for example, about several seconds), since the voltage of the secondary battery unit 50 fluctuates and becomes unstable, the time when the elapsed time (for example, about 10 seconds) has elapsed is set as the starting point of the integration time. When calculating the state of charge (SOC) of the secondary battery unit 50 at the start of the integration time, it is necessary to obtain the OCV (open circuit voltage, open circuit voltage) at the start of the integration time. By providing an elapsed time until the voltage of the secondary battery unit 50 is stabilized, the OCV at the start of the integration time can be accurately obtained, so that the SOC and the second full charge capacity can be accurately determined. It can be calculated, and the reliability of the calculation of the full charge capacity can be improved.

  The identification unit 25 has a function as an end point identification unit. When the switching determination unit 14 determines that the secondary battery unit 50 is discharged, the charging rate of the secondary battery unit 50 decreases to a predetermined lower limit. The time point (time point t3 in the examples of FIGS. 3 to 5) before the time point (time point t4 in the examples of FIGS. 3 to 5) is specified as the end time point of the integration time. The time point before the time point of falling to the predetermined lower limit value may be, for example, a time point one second before the time point of falling, but is not limited to one second.

  Accordingly, the discharge current can be integrated until immediately before the charging rate of the secondary battery unit 50 falls to the predetermined lower limit and the mode is switched from discharging to charging. If the time for integrating the discharge current can be lengthened, the calculated integrated value increases, and the integrated value for the decrease in the charging rate when estimating the second full charge capacity can be increased and estimated. The error of the second full charge capacity can be reduced.

  The weighting unit 26 assigns a first weighting factor to the first full charge capacity estimated by the first estimation unit 19 and assigns a second weighting factor to the second full charge capacity estimated by the second estimation unit 20. . The full charge capacity calculation unit 23 calculates the full charge capacity of the secondary battery unit 50 by assigning a weighting coefficient by the weighting unit 26.

  For example, the first weighting coefficient for the first full charge capacity C1 is α1, and the first weighting coefficient for the second full charge capacity C2 is α2. Here, it is assumed that α1 + α2 = 1. The full charge capacity C of the secondary battery unit 50 can be calculated by, for example, C = C1 × α1 + C2 × α2. Thereby, a higher weighting coefficient is assigned to the higher reliability, and a highly reliable full charge capacity can be calculated as a whole.

  The current difference calculation unit 27 calculates the difference between the currents before and after switching between charging and discharging of the secondary battery unit 50. For example, assuming that the current before switching between charging and discharging of the secondary battery unit 50 is Ib and the current after switching between charging and discharging of the secondary battery unit 50 is Ic, the difference between the currents is calculated by (Ic−Ib). Can be.

  When the current difference calculated by the current difference calculation unit 27 is equal to or larger than a predetermined current threshold, the weighting unit 26 sets the first weighting coefficient to be larger than the second weighting coefficient. When the current difference (Ic-Ib) is equal to or greater than the predetermined current threshold, the calculation accuracy of the internal resistance is improved, and the reliability of the first full charge capacity is increased. Therefore, by making the first weighting coefficient corresponding to the first full charge capacity larger than the second weighting coefficient, a highly reliable full charge capacity can be calculated as a whole.

  When the integrated value calculated by the current integrated value calculation unit 17 is equal to or greater than a predetermined integration threshold, the weighting unit 26 sets the second weighting coefficient to be larger than the first weighting coefficient. When the integrated value is equal to or larger than the predetermined integrated threshold, the integrated value with respect to the amount of decrease in the charging rate when estimating the second full charge capacity can be increased, and the reliability of the second full charge capacity increases. Therefore, by making the second weighting coefficient corresponding to the second full charge capacity larger than the first weighting coefficient, it is possible to calculate the full charge capacity with high reliability as a whole.

  Next, the operation of the battery monitoring device 100 according to the present embodiment will be described. 9, 10, and 11 are flowcharts illustrating an example of a processing procedure of the battery monitoring device 100 according to the present embodiment. Hereinafter, for the sake of convenience, the subject of the processing will be described as the control unit 10. The control unit 10 acquires the voltage and current of the secondary battery unit 50 at a predetermined sampling cycle (S11), and acquires stop information of the vehicle (S12). Note that the acquired stop information can include a predicted stop start time, a stop time, and the like.

  The control unit 10 determines whether or not the vehicle has stopped (S13). If the vehicle has not stopped (NO in S13), the process of step S13 is continued. When the vehicle has stopped (YES in S13), control unit 10 determines whether or not the vehicle stop time is equal to or longer than the capacity calculation required time (S14). The time required for calculating the capacity may be the integration time illustrated in FIGS. 3 to 5, may be a value obtained by adding a voltage stabilization wait time to the integration time, may be a value obtained by adding a predetermined time to the integration time, or may be a value obtained by adding the predetermined time to the integration time. The sum of the voltage stabilization wait time and the predetermined time may be used.

  When the vehicle stop time is equal to or longer than the capacity calculation required time (YES in S14), control unit 10 determines whether or not the SOC reaches the lower limit while the vehicle is stopped (S15). If the SOC reaches the lower limit while the vehicle is stopped (YES in S15), control unit 10 determines whether or not the voltage stabilization wait time has elapsed from the start of discharging (S16).

  If the voltage stabilization wait time has not elapsed (NO in S16), control unit 10 continues the processing in step S16. When the voltage stabilization wait time has elapsed (YES in S16), the control unit 10 acquires the voltage V (t2) and the current I (t2) at the start time t2 of the integration time (S17), and integrates the discharge current ( S18).

  The control unit 10 determines whether or not the current time is a time t3 that is a predetermined time earlier than the arrival time t4 of the SOC lower limit value (S19), and if the current time is not the time t3 (NO in S19). ), The processing after step S18 is continued. When the current time point is time point t3 (YES in S19), control unit 10 determines whether or not the integrated value of the discharge current is equal to or greater than a threshold value (S20). Note that the threshold value used in step S20 can be set to a value smaller than the integration threshold value when determining the weight.

  When the integrated value of the discharge current is equal to or larger than the threshold (YES in S20), it is determined that the error of the integrated value is small, and the control unit 10 determines the voltage V (t3) and the current I (t3) at the end time t3 of the integrated time. Is acquired (S21), and the integrated current value ΔI over the integration time is calculated (S22).

  The control unit 10 determines whether or not there is a switch from discharging to charging (S23). If there is no switching (NO in S23), the process of step S23 is continued. When there is a switch from discharging to charging (YES in S23), the control unit 10 acquires the voltage Vb and the current Ib sampled immediately before the switching (S24).

  The control unit 10 determines whether or not the standby time Tw has elapsed from the time point of switching from discharging to charging (S25). If the standby time Tw has not elapsed (NO in S25), the process of step S25 is continued. . If the standby time Tw has elapsed (YES in S25), the control unit 10 acquires the voltage Vc and the current Ic sampled after the standby time Tw has elapsed (S26), and calculates the internal resistance R (S27).

  The control unit 10 converts the calculated internal resistance R into an internal resistance reference value Rz (S28), and estimates the first full charge capacity C1 (S29). The control unit 10 calculates the OCV at the start time t2 and the end time t3 of the integration time (S30), and calculates the start time t2 and the end time t3 of the integration time from each OCV at the start time t2 and the end time t3 of the integration time. (S31), and the second full charge capacity C2 is estimated (S32).

  The control unit 10 determines whether the absolute value of the difference between the first full charge capacity C1 and the second full charge capacity C2 is equal to or smaller than a difference threshold (S33), and the absolute value of the difference is equal to or smaller than the difference threshold. In this case (YES in S33), the full charge capacity C is calculated, and the process of step S35 described later is performed. When the absolute value of the difference is not smaller than or equal to the difference threshold value (NO in S33), the control unit 10 performs the process of step S35 described below without performing the process of step S34.

  Also, when the vehicle stop time is not longer than the capacity calculation required time (NO in S14), when the SOC does not reach the lower limit value while the vehicle is stopped (NO in S15), or when the integrated value of the discharge current is not more than the threshold value (NO in S20), control unit 10 performs processing in step S35 described later.

  The control unit 10 determines whether or not to end the processing (S35). If the processing is not to be ended (NO in S35), the processing from step S11 is continued, and if the processing is to be ended (YES in S35), the processing is ended. To end.

  The full charge capacity calculation device (battery monitoring device 100) of the present embodiment can be realized using a general-purpose computer including a CPU (processor), a RAM (memory), and the like. That is, a computer program that defines the procedure of each process as shown in FIGS. 9 to 11 is loaded into a RAM (memory) provided in the computer, and the computer program is executed by a CPU (processor). Thus, a full charge capacity calculation device (battery monitoring device 100) can be realized.

  As described above, according to the present embodiment, the first full charge capacity C1 and the second full charge capacity C2 are estimated by two different methods, and the first full charge capacity C1 and the second full charge capacity C2 are estimated. Is determined, and the full charge capacity of the secondary battery unit 50 is calculated according to the determination result. Therefore, the full charge capacity of the secondary battery unit 50 can be calculated with high accuracy.

  In addition, by utilizing the predicted signal stop time, it is possible to determine in advance whether or not the full charge capacity of the secondary battery unit 50 can be calculated while the vehicle is stopped, thereby preventing unnecessary processing load from being generated. it can.

  Further, a voltage stabilization wait time is provided starting from the vehicle stop time obtained from the signal stop prediction time (stop information), and the time when the voltage stabilization wait time has elapsed is regarded as the start time of the integration time, and the second full charge capacity C2 Since the time required for the estimation or the calculation of the integrated value of the discharge current is set, a stable voltage after discharging can be sampled and obtained while securing the necessary integrated time.

  In the above-described embodiment, the secondary battery unit 50 has been described as a lithium ion battery. However, the secondary battery unit 50 is not limited to a lithium ion battery. can do.

  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 Temperature acquisition part 14 Switching determination part 15 Standby time specification part 16 Resistance calculation part 17 Current integrated value calculation part 18 Charge rate calculation part 19 1st estimation part 20 2nd estimation part 21 Stop information acquisition unit 22 Open circuit voltage calculation unit 23 Full charge capacity calculation unit 24 Fall time calculation unit 25 Identifying unit 26 Weighting unit 27 Current difference calculation unit 28 Storage unit 29 Timer 50 Secondary battery unit 51 Cell 52 Voltage sensor 53 Current sensor 54 Temperature sensor 100 Battery monitoring device

Claims (10)

A full charge capacity calculation device that calculates a full charge capacity of a secondary battery mounted on a vehicle,
A storage unit for storing related information relating the internal resistance and the discharge capacity of the secondary battery,
An internal resistance calculation unit that calculates an internal resistance based on a voltage and a current before and after switching between charging and discharging of the secondary battery,
A first estimator for estimating a first full charge capacity of the secondary battery based on the internal resistance calculated by the internal resistance calculator and the related information;
An integrated value calculating unit that calculates an integrated value of a discharge current over an integrated time when the secondary battery is discharged,
A reduction amount calculation unit that calculates a reduction amount of the charging rate of the secondary battery at the integration time,
A second estimator for estimating a second full charge capacity of the secondary battery based on the integrated value calculated by the integrated value calculator and the reduction amount calculated by the reduction amount calculator;
A full charge capacity calculator that calculates a full charge capacity of the secondary battery based on the first full charge capacity estimated by the first estimator and the second full charge capacity estimated by the second estimator.
The full charge capacity calculator,
When the difference between the first full charge capacity estimated by the first estimator and the second full charge capacity estimated by the second estimator is equal to or smaller than a predetermined difference threshold, the full charge capacity of the secondary battery is calculated. Full charge capacity calculator. An acquisition unit that acquires the stop time of the vehicle,
A determination unit that determines whether or not to start discharging of the secondary battery based on the stop of the vehicle.
The internal resistance calculator, the first estimator, the integrated value calculator, the decrease amount calculator, the second estimator, and the full charge capacity calculator,
The full charge capacity calculation device according to claim 1, wherein the determination unit determines that the secondary battery is discharged, and performs each process when the stop time acquired by the acquisition unit is longer than the integration time. When the determination unit determines that the secondary battery is discharged, a descent time for calculating a descent time from the time when the discharge of the secondary battery starts to the time when the charging rate of the secondary battery falls to a predetermined lower limit value. Equipped with a calculation unit,
The internal resistance calculator, the first estimator, the integrated value calculator, the decrease amount calculator, the second estimator, and the full charge capacity calculator,
The full charge capacity calculation device according to claim 2, wherein when the stop time of the vehicle is longer than the descent time, each process is performed.   When the determination unit determines that the secondary battery is discharged, a start time specifying unit that specifies a time point at which a predetermined elapsed time has elapsed from a discharge start time point of the secondary battery as a start time point of the integration time is provided. The full charge capacity calculation device according to claim 2 or 3.   When the determining unit determines that the secondary battery is discharged, an end time specifying unit that specifies a time before the time when the charging rate of the secondary battery drops to a predetermined lower limit value as the end time of the integration time. The full charge capacity calculation device according to any one of claims 2 to 4, further comprising: A weighting unit that assigns a first weighting coefficient to the first full charge capacity estimated by the first estimation unit, and assigns a second weighting coefficient to the second full charge capacity estimated by the second estimation unit;
The full charge capacity calculator,
The full charge capacity calculation device according to any one of claims 1 to 5, wherein the weighting unit calculates a full charge capacity of the secondary battery by assigning a weighting coefficient. A current difference calculation unit that calculates a difference between currents before and after switching between charging and discharging of the secondary battery,
The weighting unit,
The full charge capacity calculation device according to claim 6, wherein the first weighting coefficient is larger than the second weighting coefficient when a difference between the currents calculated by the current difference calculation unit is equal to or greater than a predetermined current threshold. The weighting unit,
The full charge capacity calculation device according to claim 6, wherein when the integrated value calculated by the integrated value calculation unit is equal to or larger than a predetermined integration threshold, the second weighting coefficient is set to be larger than the first weighting coefficient. A computer program for causing a computer to calculate a full charge capacity of a secondary battery mounted on a vehicle,
Computer
An internal resistance calculation unit that calculates an internal resistance based on a voltage and a current before and after switching between charging and discharging of the secondary battery,
A first estimating unit that estimates a first full charge capacity of the secondary battery based on related information that associates the internal resistance and the discharge capacity of the secondary battery and the calculated internal resistance;
An integrated value calculating unit that calculates an integrated value of a discharge current over an integrated time when the secondary battery is discharged,
A reduction amount calculation unit that calculates a reduction amount of the charging rate of the secondary battery at the integration time,
A second estimating unit that estimates a second full charge capacity of the secondary battery based on the calculated integrated value and the reduced amount;
Functioning as a full charge capacity calculation unit that calculates a full charge capacity of the secondary battery based on the estimated first full charge capacity and the second full charge capacity;
The full charge capacity calculator,
A computer program for calculating a full charge capacity of the secondary battery when a difference between the estimated first full charge capacity and the second full charge capacity is equal to or less than a predetermined difference threshold. A full charge capacity calculation method for calculating a full charge capacity of a secondary battery mounted on a vehicle,
The related information relating the internal resistance and the discharge capacity of the secondary battery is stored in the storage unit,
The internal resistance calculation unit calculates the internal resistance based on the voltage and current before and after switching of the charge and discharge of the secondary battery,
A first estimator estimates a first full charge capacity of the secondary battery based on the calculated internal resistance and the related information,
The integrated value calculation unit calculates the integrated value of the discharge current over the integrated time when the secondary battery is discharged,
The reduction amount calculation unit calculates the reduction amount of the charging rate of the secondary battery at the integration time,
A second estimator estimates a second full charge capacity of the secondary battery based on the calculated integrated value and the reduced amount,
A full charge capacity calculation unit calculates a full charge capacity of the secondary battery based on the estimated first full charge capacity and the second full charge capacity,
If the difference between the first full charge capacity and the second full charge capacity estimated is equal to or smaller than the predetermined difference threshold, the full charge capacity calculation method of the full charge capacity calculation unit a full charge capacity of the secondary battery is calculated.

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