SOC-OCV map update system

Abstract

To provide a SOC-OCV map update system capable of accurately updating a SOC-OCV map without hindering a user from using an electric vehicle, an electric aircraft, etc., in a case where a battery is deteriorated.SOLUTION: In a SOC-OCV map update system 1, a battery capacity SOC of a battery 2 is estimated based on a discharge current Iout measured by a discharge current measuring section 3, an open circuit voltage OCV of the battery 2 is calculated based on a voltage V of the battery 2 measured by a voltage measuring section 4. A map update section 5 capable of updating a SOC-OCV map M while associating the battery capacity SOC with the open circuit voltage OCV is provided. The map updating section 5 has information of a polarized voltage Vp after the lapse of a predetermined time t1 from discharge stop of the battery 2, and the open circuit voltage OCV is calculated by adding the polarized voltage Vp calculated from the information to the voltage V of the battery 2 measured by the voltage measuring section 4 after the lapse of the predetermined time t1 from the discharge stop from the battery 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a SOC-OCV map update system. [Background technology]

[0002] Electric vehicles and electric aircraft are equipped with batteries such as lithium-ion batteries. If the vehicle continues to run or fly without being aware that the battery capacity SOC (State Of Charge) is getting low, it may lead to unexpected accidents. Therefore, in electric vehicles, electric aircraft, etc., a control unit that controls running and flight often has a SOC-OCV map in advance that associates the battery capacity SOC with an open circuit voltage (OCV) in order to grasp the battery capacity SOC. Then, the control unit is configured to estimate the battery capacity SOC using the SOC-OCV map based on the measured battery voltage.

[0003] However, it is known that when a battery deteriorates through repeated charging and discharging, the relationship between the battery capacity SOC and the open circuit voltage OCV deviates from the predetermined SOC-OCV map M0, as shown in FIG. In such a state, if the battery capacity SOC is estimated based on the SOC-OCV map before the battery deteriorates, the estimated battery capacity SOC may be higher than the actual battery capacity SOC, which may result in a situation such as the battery running out.

[0004] Therefore, when the battery deteriorates, it is desirable to update the SOC-OCV map to a SOC-OCV map for the deteriorated state of the battery. For example, Patent Document 1 discloses a technique for periodically measuring the voltage and current of a battery while the battery is fully charged or fully discharged between a lower limit voltage and an upper limit voltage, recording data on the measured voltage and current, and updating the SOC-OCV map based on the data. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2020-524803 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if the SOC-OCV map is not accurate, there is a concern that the accuracy of the battery capacity SOC estimated based on the SOC-OCV map may deteriorate. Therefore, if the battery capacity SOC and open circuit voltage OCV are measured over a period of time when the battery deteriorates, as they were when the battery was shipped from the factory, a highly accurate SOC-OCV map can be obtained after the battery has deteriorated. However, taking such a long time to measure the battery capacity SOC and the open circuit voltage OCV would hinder users from using electric vehicles, electric aircraft, etc.

[0007] The present invention has been made in consideration of the above-mentioned points, and has an object to provide a SOC-OCV map updating system that can accurately update the SOC-OCV map when a battery deteriorates, without interfering with the user's use of an electric vehicle, electric aircraft, etc. [Means for solving the problem]

[0008] To solve the above problems, one embodiment of the present invention provides a SOC-OCV map update system. In the stem, A battery; a discharge current measuring unit capable of measuring a discharge current discharged from the battery; A voltage measuring unit capable of measuring a voltage of the battery; a map update unit that estimates a battery capacity of the battery based on the discharge current measured by the discharge current measurement unit, calculates an open circuit voltage of the battery based on the voltage of the battery measured by the voltage measurement unit, and updates a SOC-OCV map by correlating the battery capacity with the open circuit voltage; an inflow current measuring unit capable of measuring an inflow current flowing into the battery during charging; Equipped with The map update unit has information on a polarization voltage after a predetermined time has elapsed since discharge from the battery was stopped, and calculates the open circuit voltage by adding the polarization voltage calculated from the information to the voltage of the battery measured by the voltage measurement unit after the predetermined time has elapsed since discharge from the battery was stopped. death, When estimating the battery capacity of the battery, the integrated value of the current flowing into the battery measured by the inflow current measuring unit while the battery is being charged from a lower limit voltage to an upper limit voltage during charging is taken as the full charge capacity, and the integrated value of the discharge current from the battery measured by the discharge current measuring unit when the battery is discharged is taken as the current integration, and the battery capacity is calculated and estimated according to the following formula (1). Battery capacity [%] = {1-current accumulation / full charge capacity} x 100 [%] … (1)

[0010] In addition, it is preferable that the map update unit updates the SOC-OCV map when a difference between the full charge capacity when the battery is not deteriorated and the full charge capacity calculated when estimating the battery capacity of the battery is larger than a threshold value. It is also preferable that the map update unit records a set of the battery capacity and the open-circuit voltage obtained by estimating the battery capacity and calculating the open-circuit voltage each time discharging from the battery is stopped, and updates the SOC-OCV map based on the set. Effect of the Invention

[0011] According to the present invention, when a battery deteriorates, it is possible to accurately update the SOC-OCV map without interfering with the user's use of an electric vehicle, electric aircraft, or the like. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing an electric vehicle or an electric aircraft to which a SOC-OCV map update system according to an embodiment of the present invention is applied. [Diagram 2]4 is a flowchart showing a procedure of a method for updating the SOC-OCV map in a map update unit. [Diagram 3] 4 is a graph showing changes in the voltage of a battery immediately after discharging is stopped. [Figure 4] FIG. 13 is a diagram illustrating an example of a table of polarization voltages after a predetermined time has elapsed since discharge was stopped. [Diagram 5] This is an image showing how a set of battery capacity and open-circuit voltage is recorded each time an electric vehicle stops or an electric aircraft lands. [Figure 6] FIG. 13 is a diagram illustrating updating of the SOC-OCV map based on each set of recorded battery capacity and open circuit voltage. [Figure 7] 1 is a diagram showing that when a battery deteriorates, the relationship between the battery capacity and the open circuit voltage deviates from the initial SOC-OCV map. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a SOC-OCV map updating system according to the present invention will be described with reference to the drawings. 1 is a block diagram showing an electric vehicle or an electric aircraft to which the SOC-OCV map update system according to this embodiment is applied. An electric vehicle or an electric aircraft will be briefly described below.

[0014] An electric vehicle or an electric aircraft is provided with, as its drive system, an electric motor 10 that generates power for rotating drive wheels, drive wings, etc. (not shown), and an inverter 11 that drives the electric motor 10. In addition, electric vehicles and electric aircraft are equipped with a control operation unit 12 such as an accelerator pedal, brake pedal, throttle lever, etc. that the pilot operates to control the vehicle, and a driving control unit (flight control unit) 13 that receives operation signals from the control operation unit 12 and controls the inverter 11.

[0015] Further, the electric vehicle or electric aircraft includes, as a power system, a battery 2 that supplies power to the inverter 11 and the like, and a battery control unit (Battery Control Unit: BCU) 14 that controls the supply of power from the battery 2 and the like. In addition, the electric vehicle or electric aircraft is equipped with a charging system including a charger 16 that receives power from a power plug 20 that is connected to a charging connector 15 during charging and outputs a charging current to the battery 2, and a charging control unit 17 that controls the charging of the battery 2 by the charger 16.

[0016] Next, the SOC-OCV map updating system 1 according to the present embodiment will be described. The SOC-OCV map updating system 1 includes a battery 2, a discharge current measuring unit 3, a voltage measuring unit 4, and a map updating unit 5. In this embodiment, the SOC-OCV map updating system 1 further includes an inflow current measuring unit 6 and a temperature measuring unit 7.

[0017] The battery 2 is formed of a secondary battery such as a lithium ion battery. As described above, the battery 2 is discharged under the control of the battery control unit 14 to supply power to the inverter 11 and the like, and is charged with a charging current output from the charger 16 during charging.

[0018] A discharge current measuring unit 3 capable of measuring a discharge current Iout discharged from the battery 2 is connected to the battery 2. Also connected to the battery 2 is a voltage measuring unit 4 capable of measuring a voltage V between the positive and negative electrodes (not shown) of the battery 2 (hereinafter referred to as the voltage V of the battery 2). In FIG. 1, the discharge current measuring unit 3 and the voltage measuring unit 4 are illustrated separately from the battery control unit 14, but they may be constructed within the battery control unit 14 or the like.

[0019] As described above, the SOC-OCV map update system 1 includes the inflow current measuring unit 6. The inflow current measuring unit 6 measures the inflow current Iin that flows into the battery 2 during charging. In this embodiment, the charging control unit 17 described above is configured to function as the inflow current measuring unit 6, but it is also possible to configure the inflow current measuring unit 6 as a device separate from the charging control unit 17. The discharge current measuring unit 3, the voltage measuring unit 4 and the inflow current measuring unit 6 (as well as the temperature measuring unit 7 described below) are all connected to the map updating unit 5 which will be described below.

[0020] Next, the map update unit 5 will be described. In addition, while Figure 1 shows a case where the map update unit 5 is constructed within the battery control unit 14, it is also possible to configure the map update unit 5 to be provided in, for example, the driving control unit (flight control unit) 13, etc.

[0021] Hereinafter, a method for updating the SOC-OCV map in the map update unit 5 will be specifically described with reference to the flowchart of Fig. 2. In addition, the operation of the SOC-OCV map updating system 1 according to this embodiment will also be described. First, the definition and calculation method of the battery capacity SOC in the SOC-OCV map update system 1 according to this embodiment will be described.

[0022] In this embodiment, the battery capacity SOC is SOC[%] = remaining capacity[Ah] / full charge capacity[Ah] x 100[%] = (Full charge capacity [Ah] - Accumulated current [Ah]) / Full charge capacity [Ah] x 100 [%] ∴SOC [%] = (1 - current accumulation [Ah] / full charge capacity [Ah]) x 100 [%] …(2) is defined as: The current integration [Ah] in the definition of the battery capacity SOC will be explained later, and first the full charge capacity [Ah] will be explained below.

[0023] [Calculating full charge capacity] In this embodiment, the full charge capacity [Ah] is calculated as the integrated value of the current flowing into the battery 2 measured by the flowing current measuring unit 6 while charging the battery 2 from the lower limit voltage (also called the discharge lower limit voltage) Vmin to the upper limit voltage (also called the charge upper limit voltage) Vmax during charging. Therefore, when the user charges the battery 2, the map update unit 5 discharges the battery 2 to the lower limit voltage Vmin (step S1) before starting charging the battery 2. This state in which the voltage V of the battery 2 is the lower limit voltage Vmin corresponds to a state in which the battery capacity SOC is 0 [%].

[0024] Then, charging of the battery 2 is started, and the charging control unit 17 charges the battery 2 up to the upper limit voltage Vmax. At that time, the map update unit 5 calculates the integrated value of the inflow current to the battery 2 measured by the inflow current measurement unit 6 during charging from the start of charging (i.e., the time integral of the inflow current Iin [A]), and sets this as the full charge capacity soh_i [Ah] (step S2).

[0025] This state in which the voltage V of the battery 2 is the upper limit voltage Vmax corresponds to a state in which the battery capacity SOC is 100 [%]. The map update unit 5 stores the calculated full charge capacity soh_i [Ah] in a memory.

[0026] [Battery deterioration determination] In this embodiment, the map update unit 5 then calculates the difference between the full charge capacity (initial full charge capacity) calculated when the battery 2 is not deteriorated, such as when it is shipped from the factory or when the battery 2 is first charged, and the full charge capacity (current full charge capacity) calculated as described above. If the difference between them is equal to or less than the threshold a (step S3; NO), the map update unit 5 determines that the battery 2 has not yet deteriorated to the extent that updating of the SOC-OCV map is necessary, and does not update the SOC-OCV map. Furthermore, when the difference is greater than the threshold value a (step S3; YES), the map update unit 5 determines that the battery 2 is deteriorated to the extent that the SOC-OCV map needs to be updated, and updates the SOC-OCV map.

[0027] When the battery 2 deteriorates, the integrated value of the inflow current Iin required to charge the battery 2 from the lower limit voltage Vmin to the upper limit voltage Vmax, i.e., the full charge capacity soh_i [Ah], becomes smaller. That is, even if the battery capacity SOC is 100[%], if the battery 2 deteriorates, the full charge capacity soh_i [Ah] actually stored in the battery 2 becomes smaller than the initial full charge capacity. Therefore, it can be determined that the greater the difference between the initial full charge capacity and the current full charge capacity soh_i, the more deteriorated the battery 2 is.

[0028] Therefore, by calculating the difference between the initial full charge capacity and the current full charge capacity soh_i as in this embodiment and determining whether or not this difference is greater than the threshold value a, it is possible to determine whether or not the battery 2 has deteriorated. The threshold value a is set to a value that can distinguish whether or not the degree of deterioration of the battery 2 has reached a level that requires updating of the SOC-OCV map.

[0029] Furthermore, with the above-described configuration, when the battery 2 is not degraded (step S3; NO), the SOC-OCV map is not updated, and a more accurate SOC-OCV map created at the time of shipment from the factory or the like can be used. Moreover, it is possible to start updating the SOC-OCV map at the time when the battery 2 deteriorates and the SOC-OCV map created at the time of shipment from the factory or the like becomes unusable (step S3; YES).

[0030] [SOC-OCV map update] In this embodiment, as described above, when the difference between the initial full charge capacity and the current full charge capacity is greater than the threshold a (step S3; YES), the map update unit 5 starts the update process of the SOC-OCV map (step S4). To update the SOC-OCV map, the map update unit 5 estimates the battery capacity SOC of the battery 2 based on the discharge current Iout measured by the discharge current measurement unit 3. Also, it calculates the open circuit voltage OCV of the battery 2 based on the voltage V of the battery 2 measured by the voltage measurement unit 4. Then, it updates the SOC-OCV map by associating the estimated battery capacity SOC with the calculated open circuit voltage OCV.

[0031] [Start current integration] When the electric vehicle or electric aircraft starts operating, the map update unit 5 starts integrating the discharge current Iout from the battery 2 measured by the discharge current measurement unit 3 when the discharge current Iout is discharged from the battery 2 (step S5). The integrated value of the discharge current Iout from the battery 2 becomes the current integration [Ah] required for calculating the battery capacity SOC described above (see formula (2) above).

[0032] [Estimation of battery capacity and calculation of open circuit voltage] Then, the map update unit 5 is configured to estimate the battery capacity SOC of the battery 2 and calculate the open circuit voltage OCV of the battery 2 each time the electric vehicle stops or the electric aircraft lands and discharging from the battery 2 stops (step S6). The reason why the above processing is performed when discharging from the battery 2 is stopped is that it is difficult to accurately calculate the open circuit voltage OCV while the discharge current Iout is being discharged from the battery 2 due to the internal resistance of the battery 2, etc.

[0033] [Estimation of battery capacity SOC] In this embodiment, the battery capacity SOC is estimated as follows. That is, the map update unit 5 continues to accumulate the discharge current Iout as described above, but when the discharge from the battery 2 stops, it stores the accumulated value of the discharge current Iout at that point in time, i.e., the current accumulation [Ah].

[0034] Then, the map update unit 5 reads out the full charge capacity [Ah] from the memory, and substitutes the current integration [Ah] and the full charge capacity [Ah] into the above formula (2) to calculate and estimate the battery capacity SOC at that time. In this manner, in this embodiment, the map update unit 5 estimates the battery capacity SOC of the battery 2 using only the current integration [Ah] (and the full charge capacity [Ah]). The map update unit 5 stores the calculated and estimated battery capacity SOC in a memory.

[0035] [Calculating the battery open circuit voltage OCV] In this embodiment, the open circuit voltage OCV of the battery 2 is calculated as follows. As described above, it is difficult to accurately calculate the open circuit voltage OCV while the discharge current Iout is being discharged from the battery 2, and even after the discharge from the battery 2 is stopped, the voltage V of the battery 2 does not stabilize due to the polarization voltage.

[0036] However, when observing the change in the voltage V of the battery 2 immediately after the discharge is stopped, as shown in FIG. 3, the voltage V of the battery 2 rises rapidly in a short period of time immediately after the discharge is stopped (t=0), and then gradually increases. The polarization voltage Vp corresponds to the difference between the open circuit voltage OCV of the battery 2 and the voltage V of the battery 2 after the discharge is stopped. In this case, it can be said that Fig. 3 shows that the polarization voltage Vp is large immediately after the discharge is stopped, but at a certain point, the polarization voltage Vp gradually decreases.

[0037] Here, as shown in FIG. 3, the above-mentioned predetermined time t1 is set as the elapsed time from when the discharge from the battery 2 is stopped until the voltage V of the battery 2 starts to gradually increase. Research by the inventors has revealed that the polarization voltage Vp at a predetermined time t1 after the discharge is stopped will be approximately the same value if the conditions of the battery 2 at the time when the discharge from the battery 2 is stopped are the same.

[0038] Conditions that may affect the magnitude of the polarization voltage Vp after a predetermined time t1 has elapsed since the discharge was stopped include, for example, the temperature T [°C] of the battery 2 at that time, and the average value Iout_ave [A] of the discharge current Iout immediately before the discharge was stopped. Research by the present inventors has shown that if these conditions are the same, the value of the polarization voltage Vp after the predetermined time t1 has elapsed since the discharge was stopped will be approximately the same. Also, if these conditions change, the value of the polarization voltage Vp after the predetermined time t1 has elapsed since the discharge was stopped will change accordingly.

[0039] Therefore, in the SOC-OCV map updating system 1 according to this embodiment, the map updating unit 5 is configured to previously store information on the polarization voltage Vp after a predetermined time t1 has elapsed since the discharge from the battery 2 was stopped and the voltage V of the battery 2 has started to gradually increase. For example, it is possible to configure the information on the polarization voltage Vp after a predetermined time t1 has elapsed since the discharge was stopped to be stored in the form of a table τ of the temperature [°C] of the battery 2 and the average value [A] of the discharge current immediately before the discharge was stopped, as shown in FIG. 4.

[0040] In this case, the map update unit 5 acquires information on the temperature T of the battery 2 from the temperature measurement unit 7 (see FIG. 1) when a predetermined time t1 has elapsed since the discharge was stopped, and acquires information on the discharge current Iout measured by the discharge current measurement unit 3 immediately before the discharge was stopped. Then, the map update unit 5 calculates the average value Iout_ave of the discharge current Iout immediately before the discharge was stopped. The map update unit 5 can be configured to refer to the table τ and determine the polarization voltage Vp using a method such as linear interpolation based on the temperature T of the battery 2 and the average value Iout_ave of the discharge current Iout immediately before the discharge is stopped.

[0041] The magnitude of the polarization voltage Vp at the time when the predetermined time t1 has elapsed since the discharge was stopped may change depending on other conditions (e.g., the magnitude of the voltage V of the battery 2 when the discharge was stopped, etc.) Also, as can be seen from Fig. 3, the magnitude of the polarization voltage Vp changes when the way in which the predetermined time t1 is set (i.e., the value of t1) is changed. Therefore, for example, it is possible to configure the above information to be stored in the form of a function with the various conditions (e.g., temperature T of battery 2, average value Iout_ave of discharge current Iout just before discharge is stopped, voltage V of battery 2, predetermined time t1, etc.) as variables.

[0042] As described above, the polarization voltage Vp corresponds to the difference between the open circuit voltage OCV of the battery 2 and the voltage V of the battery 2 after the discharge has stopped. That is, as shown in FIG. 3, the open circuit voltage OCV of the battery 2 can be calculated by adding the polarization voltage Vp to the voltage V of the battery 2 after the discharge is stopped. Open circuit voltage OCV = voltage of battery 2 after discharge stops V + polarization voltage Vp … (3)

[0043] Therefore, the map update unit 5 calculates the open circuit voltage OCV of the battery 2 by adding the polarization voltage Vp calculated from the information as described above to the voltage V of the battery 2 measured by the voltage measurement unit 4 after a predetermined time t1 has elapsed since the discharge from the battery 2 was stopped. By configuring in this manner, it is possible to calculate the open circuit voltage OCV of battery 2 even when the voltage V of battery 2 is not stable due to the polarization voltage Vp after discharge from battery 2 is stopped, i.e., when the measured voltage V of battery 2 gradually increases.

[0044] [Recording the set of battery capacity SOC and open circuit voltage OCV] Next, the map update unit 5 associates the battery capacity SOC of the battery 2 estimated when the discharge from the battery 2 is stopped and the calculated open circuit voltage OCV to create a set, and then stores the set of the battery capacity SOC and the open circuit voltage OCV in the memory (step S7). Unless the user charges the battery 2 (step S8; NO), the map update unit 5 repeats the processes of steps S6 and S7 each time the electric vehicle 50 stops or the electric aircraft 51 lands and discharging from the battery 2 stops as shown in Fig. 5. The map update unit 5 then records the obtained set of battery capacity SOC and open circuit voltage OCV.

[0045] [SOC-OCV map update] By repeating the above process, when the next charging of battery 2 is performed (step S8; YES), each set (see x in the figure) of battery capacity SOC from near the upper limit (100%) to near the lower limit (0%) will be recorded in memory, as shown in Figure 6. Therefore, in this embodiment, the map update unit 5 updates the SOC-OCV map M based on each set of the battery capacity SOC and the open circuit voltage OCV of the battery 2 obtained by recording (step S9).

[0046] In this case, the map update unit 5 plots a set of the battery capacity SOC and the open circuit voltage OCV on a graph with the horizontal axis representing SOC and the vertical axis representing OCV, as shown in FIG. Then, the SOC-OCV map M can be created and updated by connecting each set by an interpolation method or approximating the set to a theoretical formula by a least squares method.

[0047] As described above, according to the SOC-OCV map updating system 1 of this embodiment, each time discharging from the battery 2 stops while the electric vehicle is stopped or while the electric aircraft is landing, the map updating unit 5 estimates the battery capacity SOC based on the discharge current Iout from the battery 2. At the same time, it calculates the open circuit voltage OCV of the battery 2 based on the voltage V of the battery 2. Then, the map update unit 5 updates the SOC-OCV map M by associating the estimated battery capacity SOC with the calculated open circuit voltage OCV.

[0048] Therefore, in this embodiment, when the battery 2 deteriorates, the SOC-OCV map M can be updated by measuring the discharge current Iout from the battery 2 and the voltage V of the battery 2 while the user is using the electric vehicle, electric aircraft, etc. Therefore, in the SOC-OCV map updating system 1 according to this embodiment, when the battery 2 deteriorates, it is possible to update the SOC-OCV map M without interfering with the user's use of an electric vehicle, electric aircraft, etc.

[0049] Moreover, according to the SOC-OCV map updating system 1 according to this embodiment, the map updating unit 5 has information on the polarization voltage Vp after the predetermined time t1 has elapsed since the discharge from the battery 2 was stopped. Then, the map update unit 5 calculates the open circuit voltage OCV of the battery 2 by adding the polarization voltage Vp calculated from the above information to the voltage V of the battery 2 measured a predetermined time t1 after the discharge from the battery 2 was stopped.

[0050] Therefore, in this embodiment, even in a state in which the voltage V of the battery 2 is not stable due to the polarization voltage Vp after the electric vehicle is stopped or the electric aircraft is landed and discharging from the battery 2 is stopped, the influence of the polarization voltage Vp can be removed and the open circuit voltage OCV can be calculated with high accuracy. Therefore, in the SOC-OCV map updating system 1 according to this embodiment, when the battery 2 deteriorates, it is possible to update the SOC-OCV map M with high accuracy.

[0051] It goes without saying that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention. For example, the electric vehicle or electric aircraft to which the SOC-OCV map update system 1 according to the present embodiment is applied may be manned or unmanned. The battery 2 is not limited to a lithium ion battery, and may be any type of battery to which the present invention is applicable. [Explanation of symbols]

[0052] 1 SOC-OCV map update system 2 Battery 3 Discharge current measuring section 4. Voltage measurement section 5. Map Update Section 6 Inflow current measurement section 17 Charging control section (inflow current measurement section) a Threshold Iin Inflow current Iout Discharge current M SOC-OCV map OCV Open Circuit Voltage SOC Battery Capacity soh_i Full charge capacity t1 Predetermined time V Battery voltage Vmax Upper limit voltage Vmin Lower limit voltage Vp Polarization voltage

Claims

1. A battery; a discharge current measuring unit capable of measuring a discharge current discharged from the battery; A voltage measuring unit capable of measuring a voltage of the battery; a map update unit that estimates a battery capacity of the battery based on the discharge current measured by the discharge current measurement unit, calculates an open circuit voltage of the battery based on the voltage of the battery measured by the voltage measurement unit, and is capable of updating an SOC-OCV map by correlating the battery capacity with the open circuit voltage; an inflow current measuring unit capable of measuring an inflow current flowing into the battery during charging; Equipped with The map update unit is a voltage measuring unit that measures a voltage of the battery after a predetermined time has elapsed since the discharge of the battery was stopped, and the voltage measuring unit measures the voltage of the battery after a predetermined time has elapsed since the discharge of the battery was stopped, and the polarization voltage calculated from the information is added to the voltage measuring unit to calculate the open circuit voltage; an SOC-OCV map updating system for estimating a battery capacity of the battery, the system being characterized in that: an integrated value of a current flowing into the battery, measured by the inflow current measuring unit while the battery is being charged from a lower limit voltage to an upper limit voltage during charging, is defined as a full charge capacity; and an integrated value of a discharge current from the battery, measured by the discharge current measuring unit when the battery is discharged, is defined as a current integration, and the battery capacity is calculated and estimated according to the following formula (1): Battery capacity [%] = {1 - current integration / full charge capacity} x 100 [%] ... (1)

2. 2. The SOC-OCV map updating system according to claim 1, wherein the map updating unit updates the SOC-OCV map when a difference between the full charge capacity in a state in which the battery is not deteriorated and the full charge capacity calculated when estimating the battery capacity of the battery is greater than a threshold value.

3. 3. The SOC-OCV map updating system according to claim 1, wherein the map updating unit records a set of the battery capacity and the open-circuit voltage obtained by estimating the battery capacity and calculating the open-circuit voltage each time discharging from the battery is stopped, and updates the SOC-OCV map based on the set.

4. A battery; a discharge current measuring unit capable of measuring a discharge current discharged from the battery; A voltage measuring unit capable of measuring a voltage of the battery; a map update unit that estimates a battery capacity of the battery based on the discharge current measured by the discharge current measurement unit, calculates an open circuit voltage of the battery based on the voltage of the battery measured by the voltage measurement unit, and is capable of updating an SOC-OCV map by correlating the battery capacity with the open circuit voltage; Equipped with The map update unit is a voltage measuring unit that measures a voltage of the battery after a predetermined time has elapsed since the discharge of the battery was stopped, and the voltage measuring unit measures the voltage of the battery after a predetermined time has elapsed since the discharge of the battery was stopped, and the polarization voltage calculated from the information is added to the voltage measuring unit to calculate the open circuit voltage; an SOC-OCV map updating system that estimates the battery capacity and calculates the open-circuit voltage, records a set of the battery capacity and the open-circuit voltage obtained each time discharging from the battery is stopped, and updates the SOC-OCV map based on the set.

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