JP2015230188A - Soc estimation device and soc estimation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately estimate a SOC of a capacitor in real time.SOLUTION: A SOC estimation device comprises: a charge-amount computation unit 34 that computes an amount of charge of a capacitor component 11 on the basis of a current detected by a current detection unit 5, a static capacitor computed by a static capacitor computation unit 31 and second resistance computed by a parallel resistance computation unit 33; a first voltage computation unit that computes a first voltage serving as a voltage of a series resistance component 12 on the basis of the current detected by the current detection unit 5 and first resistance computed by a series resistance computation unit 32; a second voltage computation unit that computes a second voltage serving as a voltage of the capacitor component 11 on the basis of the static capacitor computed by the static capacitor computation unit 31 and the amount of charge computed by the charge-amount computation unit 34; an open voltage computation unit 35 that subtracts the first voltage and second voltage from a voltage between terminals to compute an open voltage of a capacitor 1; and a SOC computation unit 36 that computes a SOC of the capacitor on the basis of the open voltage.

Description

  The present invention relates to an SOC estimation device and an SOC estimation method for estimating a state of charge (SOC) of a capacitor.

  As an apparatus for estimating the SOC, Patent Document 1 discloses a charge that calculates a current charging rate of a secondary battery from an actually measured voltage of the secondary battery with reference to a table indicating a relationship between an open voltage of the secondary battery and a charging rate. A rate calculation unit, and an output unit that outputs a calculation result of the charge rate calculation unit as a charge rate of the secondary battery when the secondary battery is determined to be in a static state by the static determination unit Is disclosed.

  As an apparatus for estimating the SOC, Patent Document 2 estimates the internal resistance value (Rdc) of the battery module from the amount of change in the battery current and the amount of change in the terminal voltage before and after the change in the battery current, and the estimated internal resistance value. It is disclosed that a voltage Va as an estimated value of the open circuit voltage is obtained using (Rdc), and the voltage Va is converted into an estimated remaining capacity SOC.

JP 2012-177588 A JP, 2014-25738, A

  In the estimation method described in Patent Document 1, since the charging rate is calculated from the open circuit voltage, in order to calculate the charging rate with high accuracy, charging / discharging is stopped and the remaining charge of the capacity component of the secondary battery is reduced. It is necessary to measure the open-circuit voltage in the discharged stable state. Therefore, it takes time to calculate the charging rate.

  On the other hand, in the estimation method described in Patent Document 2, it is possible to estimate the charging rate in real time. However, since the open circuit voltage is estimated based only on the estimated internal resistance value, the remaining charge of the capacitance component is not taken into account and the estimated remaining capacity value SOC cannot be estimated with high accuracy.

  The present invention has been made in view of the above problems, and an object thereof is to accurately estimate the SOC of a battery in real time.

  The present invention relates to an SOC estimation device that estimates the SOC of a capacitor, a voltage detection unit that detects a voltage between terminals of the capacitor, a current detection unit that detects a current of the capacitor, and a capacitance component of the capacitor. A capacitance calculating unit that calculates a capacitance; a series resistance calculating unit that calculates a first resistance of a series resistance component in series with the capacitance component of the internal resistance of the capacitor; and the capacitance of the internal resistance of the capacitor. A parallel resistance calculation unit that calculates a second resistance of a parallel resistance component in parallel with the component, a current detected by the current detection unit, a capacitance calculated by the capacitance calculation unit, and the parallel resistance Based on the second resistance calculated by the calculation unit, the charge amount calculation unit for calculating the charge amount of the capacitance component, the current detected by the current detection unit, and the series resistance calculation unit Based on the first resistance, the series Based on the first voltage calculation unit that calculates the first voltage that is the anti-component voltage, the capacitance calculated by the capacitance calculation unit, and the charge amount calculated by the charge amount calculation unit, A second voltage calculation unit that calculates a second voltage that is a voltage of the capacitance component; and an open voltage calculation unit that calculates an open voltage of the battery by subtracting the first voltage and the second voltage from the voltage between the terminals. And an SOC calculation unit for calculating the SOC of the battery based on the open circuit voltage.

  The present invention is also an SOC estimation method for estimating the SOC of a capacitor, wherein a capacitance of the capacitor component of the capacitor is calculated, and a series resistance component in series with the capacitor component of the internal resistance of the capacitor is calculated. 1 resistance is calculated, a second resistance of a parallel resistance component parallel to the capacitance component among the internal resistance of the capacitor is calculated, and the current of the capacitor, the capacitance of the capacitance component, and the second resistance are calculated. And calculating a first voltage that is a voltage of the series resistance component based on the current of the capacitor and the first resistance, and calculating the capacitance of the capacitance component. Based on the amount of charge, a second voltage that is a voltage of the capacitive component is calculated, an open circuit voltage of the capacitor is calculated by subtracting the first voltage and the second voltage from a terminal voltage of the capacitor, The power storage based on the open circuit voltage Characterized by calculating the SOC.

  The present invention calculates the open circuit voltage by subtracting the first voltage of the series resistance component and the second voltage of the capacitance component from the voltage between the terminals, and calculates the SOC from the open circuit voltage, Calculation is performed based on the charge amount of the capacitive component of the capacitor. Therefore, it is possible to accurately estimate the SOC of the battery in real time.

It is a block diagram of the SOC estimation apparatus which concerns on embodiment of this invention. It is an equivalent circuit schematic of the electrical storage device to which the SOC estimation apparatus which concerns on embodiment of this invention is applied. It is a control block diagram of the SOC estimation apparatus which concerns on embodiment of this invention. It is the 1st map in which the relationship between the temperature of a capacitor and a capacitance was defined. It is the 2nd map in which the relationship between the temperature of a capacitor and the resistance of a series resistance component was defined. It is the 3rd map in which the relation between the temperature of a capacitor and the resistance of a parallel resistance component was defined. It is a 4th map in which the relationship between the open circuit voltage of a capacitor | condenser and SOC was prescribed | regulated. It is a figure which shows the time change of the voltage between terminals of a capacitor | condenser.

  Hereinafter, an SOC estimation apparatus 100 according to an embodiment of the present invention will be described with reference to the drawings.

  First, an outline of the SOC estimation apparatus 100 will be described with reference to FIG. FIG. 1 is a configuration diagram of the SOC estimation device 100.

  The SOC estimation device 100 is a device that estimates a state of charge (SOC) of the battery 1 that drives the load 2 such as a motor.

  The battery 1 is a secondary battery that can be charged and discharged, and is, for example, a lithium ion battery or a nickel metal hydride battery. The capacitor 1 may be composed of a single cell, or may be a plurality of cells connected in series. The capacitor 1 is not limited to a secondary battery, and may be any one that charges and discharges electric charge by electrostatic capacity, and may be an electric double layer capacitor, a lithium ion capacitor, or the like.

  The battery 1 is connected to the load 2 via a wire 3 connected to the anode, a wire 4 connected to the cathode, and a power conversion circuit (not shown) for switching the charge / discharge state of the battery 1.

  The SOC estimation apparatus 100 is connected between the wiring 3 and the wiring 4, and includes a voltage sensor 5 as a voltage detection unit that detects a voltage between terminals of the capacitor 1, and a current detection that detects the current of the capacitor 1 connected to the wiring 3. A current sensor 6 as a unit, and a temperature sensor 7 as a temperature detection unit that is connected to the capacitor 1 and detects the temperature of the capacitor 1.

  The voltage sensor 5, the current sensor 6, and the temperature sensor 7 detect the voltage, current, and temperature between the terminals of the battery 1 every predetermined measurement period, for example, every 10 msec. For example, the voltage sensor 5 detects the voltage between the electrodes of the cell. The current sensor 6 detects the magnitude of the current flowing through the cell. The temperature sensor 7 detects the surface temperature of the case housing the cell.

  The SOC estimation device 100 further includes a controller 10 that calculates the open circuit voltage of the battery 1 based on the detection results input from the sensors 5, 6, and 7, and calculates the SOC of the battery 1 based on the open voltage. . The open circuit voltage is a voltage between terminals of the battery 1 when charging / discharging of the battery 1 is stopped.

  An equivalent circuit of the battery 1 can be expressed as shown in FIG. An equivalent circuit of the battery 1 will be described with reference to FIG.

  The equivalent circuit of the capacitor 1 includes a capacitance component 11 in which charges are stored, a series resistance component 12 in series with the capacitance component 11 of the internal resistance of the capacitor 1, and a parallel resistance in parallel with the capacitance component 11 of the internal resistance of the capacitor 1. And component 13.

  The series resistance component 12 is a resistance that is not related to the charge / discharge reaction, and is, for example, a resistance of a wiring or the like that connects the cells. The parallel resistance component 13 is a resistance that varies depending on the charge / discharge reaction.

  When the inter-terminal voltage of the capacitor 1 is V, the voltage of the series resistance component 12 (first voltage) is V1, and the voltage of the capacitance component 11 and the parallel resistance component 13 (second voltage) is V2, the open circuit voltage E of the capacitor 1 is And represented by the following formula (1).

[Equation 1]
E = V- (V1 + V2) (1)

  Next, the controller 10 of the SOC estimation apparatus 100 will be described with reference to FIG. FIG. 3 is a control block diagram of the SOC estimation apparatus 100.

  The controller 10 includes a capacitance calculation unit 31 that calculates the capacitance of the capacitance component 11, a series resistance calculation unit 32 that calculates the resistance (first resistance) of the series resistance component 12, and the resistance ( A parallel resistance calculation unit 33 for calculating (second resistance).

  The capacitance calculation unit 31 stores a first map (see FIG. 4) in which the relationship between the temperature of the battery 1 and the capacitance is defined. The capacitance calculation unit 31 acquires the temperature of the battery 1 from the temperature sensor 7 and calculates the capacitance corresponding to the acquired temperature with reference to the first map. As described above, the capacitance calculating unit 31 calculates the capacitance of the capacitance component 11 based on the predetermined first map and the detection result of the temperature sensor 7.

  The series resistance calculation unit 32 stores a second map (see FIG. 5) in which the relationship between the temperature of the battery 1 and the resistance of the series resistance component 12 is defined. The series resistance calculation unit 32 acquires the temperature of the battery 1 from the temperature sensor 7 and calculates the resistance corresponding to the acquired temperature with reference to the second map. As described above, the series resistance calculation unit 32 calculates the resistance of the series resistance component 12 based on the predetermined second map and the detection result of the temperature sensor 7.

  The parallel resistance calculation unit 33 stores a third map (see FIG. 6) in which the relationship between the temperature of the battery 1 and the resistance of the parallel resistance component 13 is defined. The parallel resistance calculation unit 33 acquires the temperature of the battery 1 from the temperature sensor 7, refers to the third map, and calculates a resistance corresponding to the acquired temperature. Thus, the parallel resistance calculation unit 33 calculates the resistance of the parallel resistance component 13 based on the predetermined third map and the detection result of the temperature sensor 7.

  The controller 10 includes a charge amount calculation unit 34 that calculates the charge amount of the capacitive component 11, an open voltage calculation unit 35 that calculates the open circuit voltage of the battery 1, and an SOC calculation unit that calculates the SOC of the battery 1 based on the open voltage. 36.

  The charge amount calculation unit 34 stores a program for calculating the charge amount of the capacitive component 11. The charge amount calculation unit 34 acquires the current of the battery 1 from the current sensor 6, acquires the calculation result from the capacitance calculation unit 31 and the parallel resistance calculation unit 33, and uses the stored program to store the capacitance component 11. Is calculated. In this way, the charge amount calculation unit 34 calculates the charge amount of the capacitance component 11 based on the detection result of the current sensor 6, the calculation result of the capacitance calculation unit 31, and the calculation result of the parallel resistance calculation unit 33. .

  The open-circuit voltage calculation unit 35 stores a program for calculating the open-circuit voltage of the battery 1. The open circuit voltage calculation unit 35 acquires the voltage and current of the battery 1 from the voltage sensor 5 and the current sensor 6, and acquires calculation results from the capacitance calculation unit 31, the series resistance calculation unit 32, and the charge amount calculation unit 34. Then, the open circuit voltage of the battery 1 is calculated using the stored program. As described above, the open circuit voltage calculation unit 35 includes the detection result of the voltage sensor 5, the detection result of the current sensor 6, the calculation result of the capacitance calculation unit 31, the calculation result of the series resistance calculation unit 32, and the charge amount calculation unit 34. Based on the result of the calculation, the open circuit voltage of the battery 1 is calculated.

  The SOC calculation unit 36 stores a fourth map (see FIG. 7) that defines the relationship between the open circuit voltage of the battery 1 and the SOC. The SOC calculation unit 36 acquires the open-circuit voltage of the battery 1 from the open-circuit voltage calculation unit 35, and calculates the SOC corresponding to the acquired open-circuit voltage with reference to the fourth map.

  Next, with reference mainly to FIGS. 2 and 3, the calculations executed by the charge amount calculation unit 34, the open circuit voltage calculation unit 35, and the SOC calculation unit 36 of the controller 10 will be described in detail.

  First, the calculation executed by the charge amount calculation unit 34 will be described. The charge amount calculation unit 34 calculates the charge amount Q of the capacitive component 11 for each calculation cycle according to the following equation (2).

[Equation 2]
Q = Q _P + (I− (Q _P / C) / R 2) × t (2)
Q _P : previous value of the charge amount [C] of the capacitance component 11 I: current [A] flowing through the series resistance component 12
C: Capacitance of capacitive component 11 [F]
R2: resistance of the parallel resistance component 13 [Ω]
t: Calculation cycle [sec]

  The formula (2) will be described in detail.

Q _P / C in the equation (2) is the voltage V2 of the capacitance component 11 and the parallel resistance component 13. Q _P is a previous value of the charge amount Q of the capacitance component 11 that is calculated by equation (2), the initial value is 0. A value calculated by the capacitance calculation unit 31 is used as the capacitance C of the capacitance component 11. Specifically, the capacitance calculator 31 calculates the capacitance C corresponding to the temperature of the battery 1 detected by the temperature sensor 7 with reference to the first map (see FIG. 4). For example, when the temperature of the battery 1 is 30 ° C., the capacitance C is calculated as 660 F from the first map of FIG.

(Q _P / C) / R2 in the equation (2) is a current I2 flowing through the parallel resistance component 13. As the resistance R2 of the parallel resistance component 13, a value calculated by the parallel resistance calculation unit 33 is used. Specifically, the parallel resistance calculation unit 33 calculates the resistance R2 corresponding to the temperature of the battery 1 detected by the temperature sensor 7 with reference to the third map (see FIG. 6). For example, when the temperature of the capacitor 1 is 30 ° C., the resistance R2 is calculated as 6.0 mΩ from the third map of FIG.

In the formula (2), I− (Q _P / C) / R2 is a current I1 flowing through the capacitive component. A value detected by the current sensor 6 is used as the current I flowing through the series resistance component 12.

(I− (Q _P / C) / R2) × t in the equation (2) is the product of the current I1 flowing through the capacitance component and the calculation cycle t, and is the amount of change in the charge of the capacitance component 11 during the calculation cycle. is there.

As described above, (2) expression in previous value Q _P of the charge amount of the capacitive component 11, by adding the amount of change in the charge of the capacitive component 11 between the calculation cycle, the charge amount of the current capacity component 11 Q is calculated.

  The charge amount calculation unit 34 calculates the charge amount Q of the capacitive component 11 for each calculation cycle using the equation (2), and can acquire the charge amount Q remaining in the capacitive component 11 in real time. In calculating the charge amount Q, the capacitance C of the capacitance component 11 is calculated with reference to the first map having characteristics depending on the temperature of the capacitor 1, and the resistance R2 of the parallel resistance component 13 is calculated by the capacitor. Calculation is performed with reference to a third map having a temperature-dependent characteristic of 1. Therefore, the charge amount Q can be calculated with high accuracy.

  Next, the calculation executed by the open circuit voltage calculation unit 35 will be described. The open-circuit voltage calculation unit 35 calculates the open-circuit voltage E of the battery 1 for each calculation cycle using the following equation (3) that is substantially the same as the above-described equation (1).

[Equation 3]
E = V− (I × R1 + Q / C) (3)
V: Voltage between terminals of capacitor 1 [V]
I: current flowing in the series resistance component 12 [A]
R1: Resistance of series resistance component 12 [Ω]
Q: Charge amount of capacitive component 11 [C]
C: Capacitance of capacitive component 11 [F]

  Formula (3) will be described in detail.

  In the equation (3), V is a voltage between terminals of the battery 1, and a value detected by the voltage sensor 5 is used.

  In the expression (3), I × R1 is the voltage V1 of the series resistance component 12 (first voltage calculated by the first voltage calculation unit). A value detected by the current sensor 6 is used as the current I flowing through the series resistance component 12. As the resistance R1 of the series resistance component 12, the value calculated by the series resistance calculation unit 32 is used. Specifically, the series resistance calculation unit 32 calculates the resistance R1 corresponding to the temperature of the battery 1 detected by the temperature sensor 7 with reference to the second map (see FIG. 5). For example, when the temperature of the capacitor 1 is 30 ° C., the resistance R1 is calculated as 9.0 mΩ from the second map of FIG.

  Q / C in the equation (3) is the voltage V2 of the capacitance component 11 and the parallel resistance component 13 (second voltage calculated by the second voltage calculation unit). The charge amount Q of the capacitance component 11 is a value calculated for each calculation cycle by the charge amount calculation unit 34, that is, the open circuit voltage calculation unit 35 receives the capacitance component 11 from the charge amount calculation unit 34 for each calculation cycle. Is obtained. A value calculated by the capacitance calculation unit 31 is used as the capacitance C of the capacitance component 11. The calculation method is the same as the calculation method described in the charge amount calculation unit 34.

  As described above, the equation (3) is obtained by subtracting the voltage V1 of the series resistance component 12 and the voltage V2 of the capacitance component 11 from the inter-terminal voltage V of the capacitor 1 to obtain the current open circuit voltage E of the capacitor 1. It is to calculate.

  The open-circuit voltage calculation unit 35 calculates the open-circuit voltage E of the battery 1 for each calculation cycle using Expression (3), and can acquire the open-circuit voltage E of the battery 1 in real time.

  Next, the calculation executed by the SOC calculation unit 36 will be described.

  The SOC calculation unit 36 calculates the SOC of the battery 1 corresponding to the open-circuit voltage E of the battery 1 calculated by the open-circuit voltage calculation unit 35 with reference to the fourth map (see FIG. 7). For example, when the open circuit voltage E is 3.95 V, the SOC is calculated as 80% from the fourth map of FIG. Since the open circuit voltage E is calculated every calculation cycle, the SOC of the battery 1 calculated by the SOC calculation unit 36 is also calculated every calculation cycle. Therefore, the SOC of the battery 1 can be grasped in real time.

  As described above, the SOC of the battery 1 is calculated and estimated by the controller 10.

  Next, the operation of the SOC estimation apparatus 100 will be described with reference to FIG. FIG. 8 is a diagram illustrating an example of a temporal change in the inter-terminal voltage V of the battery 1.

  The inter-terminal voltage V of the battery 1 rises as the battery 1 is charged. After the charge is stopped, the voltage V drops rapidly and then slowly drops and stabilizes after a predetermined time. FIG. 8 shows an example in which immediately after the charging is stopped at time t1, the inter-terminal voltage V drops sharply, then gradually drops to time t2, and becomes the open circuit voltage E stably at time t2.

  The rapid voltage drop V1 immediately after stopping the charging in FIG. 8 is caused by the fact that the current flowing through the series resistance component 12 becomes 0A. That is, in the above equation (3), the current I flowing through the series resistance component 12 is 0 A, and the voltage V1 (= I × R1) of the series resistance component 12 is 0 V.

  The gradual voltage drop V2 until time t2 in FIG. 8 is caused by a current leaking from the capacitive component 11 to the parallel resistance component 13 and the charge amount of the capacitive component 11 being reduced, and is caused by self-discharge. It is. That is, in the above equation (3), the charge amount Q of the capacitive component 11 decreases and the voltage V2 (= Q / C) of the capacitive component 11 drops.

  Thus, the open circuit voltage E is calculated by subtracting the abrupt voltage drop V1 and the gradual voltage drop V2 from the inter-terminal voltage V. In formula (3), I × R1 (voltage V1 of the series resistance component 12) corresponds to a sudden voltage drop V1, and Q / C (voltage V2 of the capacitance component 11 and the parallel resistance component 13) becomes a gradual voltage drop V2. Equivalent to. Therefore, if the equation (3) is used, the sudden voltage drop V1 and the gradual voltage drop V2 can be calculated even during charging and discharging, and the open circuit voltage E of the battery 1 can be predicted. That is, the open circuit voltage E can be predicted in consideration of a transient change in the inter-terminal voltage V by using the expression (3).

  In calculating the sudden voltage drop V1 (= I × R1) by the expression (3), the resistance R1 of the series resistance component 12 is referred to the second map having the characteristics depending on the temperature of the capacitor 1 as described above. Is calculated. Therefore, the sudden voltage drop V1 can be calculated with high accuracy.

  In calculating the gradual voltage drop V2 (= Q / C) using the equation (3), the capacitance C of the capacitance component 11 is the first map having the characteristics depending on the temperature of the battery 1 as described above. Calculated with reference. The charge amount Q of the capacitive component 11 is a value calculated by the charge amount calculation unit 34 for each calculation cycle. The charge amount calculation unit 34 calculates the charge amount Q remaining in the capacitive component 11 in real time using equation (2). Therefore, the gradual voltage drop V2 can be calculated with high accuracy.

  In this way, the rapid voltage drop V1 (= I × R1) and the gradual voltage drop V2 (= Q / C) can be calculated with high accuracy. However, the open circuit voltage E of the battery 1 can be accurately predicted. Since the SOC of the battery 1 is calculated based on the open circuit voltage E predicted by the equation (3), the SOC of the battery 1 can be estimated with high accuracy.

  According to the above embodiment, there exist the effects shown below.

  The SOC estimation apparatus 100 calculates the open circuit voltage E by subtracting the voltage V1 of the series resistance component 12 and the voltage V2 of the capacitance component 11 from the inter-terminal voltage V, and calculates the SOC from the open circuit voltage E. The voltage V2 (= Q / C) of the capacitive component 11 is calculated based on the charge amount Q remaining in the capacitive component 11 of the battery 1, and the charge amount Q is calculated in real time for each calculation cycle. Therefore, since the open circuit voltage E of the battery 1 can be accurately predicted, the SOC of the battery 1 can be accurately estimated in real time.

  In the conventional method of measuring the open-circuit voltage in a stable state after charging and discharging and estimating the SOC from the measured open-circuit voltage, an accurate SOC can be estimated, but it takes time to estimate. In addition, it is difficult to estimate an accurate SOC with a conventional method for estimating the SOC in real time. However, since the SOC estimating apparatus 100 can accurately predict the open circuit voltage of the battery 1 even during charging and discharging, the SOC of the battery 1 can be accurately estimated in real time.

  In addition, in the conventional method for estimating the SOC in real time, since the estimation error is large, it is necessary to provide a margin for the operating voltage range in order to prevent overvoltage. However, since the SOC estimation apparatus 100 can accurately estimate the SOC of the battery 1, the operating voltage range can be made wider.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

DESCRIPTION OF SYMBOLS 100 SOC estimation apparatus 1 Capacitor 2 Load 5 Voltage sensor (voltage detection part)
6 Current sensor (current detector)
7 Temperature sensor 10 Controller 11 Capacitance component 12 Series resistance component 13 Parallel resistance component 31 Capacitance calculation unit 32 Series resistance calculation unit 33 Parallel resistance calculation unit 34 Charge amount calculation unit 35 Open-circuit voltage calculation unit 36 SOC calculation unit

Claims (4)

An SOC estimation device for estimating the SOC of a battery,
A voltage detector for detecting a voltage between terminals of the capacitor;
A current detector for detecting the current of the capacitor;
A capacitance calculating unit that calculates the capacitance of the capacitive component of the capacitor;
A series resistance calculation unit that calculates a first resistance of a series resistance component in series with the capacitance component of the internal resistance of the capacitor;
A parallel resistance calculation unit for calculating a second resistance of a parallel resistance component in parallel with the capacitance component of the internal resistance of the capacitor;
Based on the current detected by the current detection unit, the capacitance calculated by the capacitance calculation unit, and the second resistance calculated by the parallel resistance calculation unit, the charge amount of the capacitance component A charge amount calculation unit for calculating
A first voltage calculation unit that calculates a first voltage that is a voltage of the series resistance component based on the current detected by the current detection unit and the first resistance calculated by the series resistance calculation unit;
A second voltage calculation unit that calculates a second voltage that is a voltage of the capacitance component based on the capacitance calculated by the capacitance calculation unit and the charge amount calculated by the charge amount calculation unit; ,
An open-circuit voltage calculator that calculates the open-circuit voltage of the battery by subtracting the first voltage and the second voltage from the inter-terminal voltage;
An SOC calculation unit for calculating the SOC of the battery based on the open circuit voltage;
An SOC estimation apparatus comprising:   The charge amount calculation unit calculates a charge amount of the capacitance component for each calculation cycle, calculates a charge change amount between calculation cycles, and sets a previous value which is a charge amount of the capacitance component calculated last time. The SOC estimation apparatus according to claim 1, wherein the charge amount of the capacitance component is calculated by adding the charge change amount.   Each of the capacitance of the capacitance component, the first resistance of the series resistance component, and the second resistance of the parallel resistance component is calculated with reference to a map having characteristics depending on the temperature of the capacitor. The SOC estimation apparatus according to claim 1, wherein the SOC estimation apparatus is characterized. An SOC estimation method for estimating the SOC of a battery,
Calculate the capacitance of the capacitive component of the capacitor,
Calculate the first resistance of the series resistance component in series with the capacitance component of the internal resistance of the capacitor,
Calculating a second resistance of a parallel resistance component in parallel with the capacitance component of the internal resistance of the capacitor;
Based on the current of the capacitor, the capacitance of the capacitive component, and the second resistance, the charge amount of the capacitive component is calculated,
Based on the current of the capacitor and the first resistance, a first voltage that is a voltage of the series resistance component is calculated,
Based on the capacitance of the capacitive component and the charge amount, a second voltage that is a voltage of the capacitive component is calculated,
Subtracting the first voltage and the second voltage from the terminal voltage of the capacitor to calculate an open circuit voltage of the capacitor;
An SOC estimation method, wherein the SOC of the battery is calculated based on the open circuit voltage.

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