JP2017083474A - Charging state reliability determination device and charging state reliability determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine reliability of an estimated value of SOC based on a value of a variable element that has correlation relationship with the SOC and is different from OCV.SOLUTION: A CPU35 determines which of a steep change region EH and a micro change region EL includes an estimated value (current integration SOC value) of SOC based on current integration and an estimated value (voltage measurement SOC value) of the SOC based on OCV, and determines reliability of the estimated value of the SOC based on the current integration.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for estimating the state of charge of a storage element.

  Conventionally, as an example of a method for estimating the state of charge (remaining capacity, also referred to as “state of charge”, hereinafter simply referred to as “SOC”) of a battery that is one of the storage elements, an open circuit voltage of the battery (hereinafter referred to as “open circuit voltage”) There is an SOC estimation method by “OCV”). This is to detect a terminal voltage value of a battery and refer to a change characteristic of the OCV with respect to the SOC of the battery, and calculate an SOC corresponding to the detected terminal voltage value as an estimated SOC value (hereinafter referred to as an SOC based on the OCV). This is called an “estimated value”.

  As another method for estimating the SOC of the battery, there is an SOC estimation method based on current integration. The SOC estimation method based on this current integration is, for example, SOC 100% when fully charged as the initial value of SOC, and thereafter, the amount of change in SOC (ΔSOC) is obtained by integrating the charge / discharge current of the battery. The SOC obtained by adding the SOC change amount to the initial value is used as an estimated SOC value (hereinafter referred to as “an estimated SOC value based on current integration”).

  By the way, in the SOC estimation method based on the OCV, in the change characteristic of the OCV with respect to the SOC, the SOC estimation based on the OCV is performed in a region where the open circuit voltage change rate that is the change amount of the OCV per unit change amount of the SOC is relatively low. There is a possibility that an error between the value and the actual value of the SOC becomes large. As a method corresponding to this, there is an SOC estimation method based on current integration. In this method, when current integration is performed for a long time, an estimated value of SOC based on current integration, for example, due to a measurement error of a current sensor, and the like. There is a problem that errors with the actual value of the SOC are integrated and become large.

  For example, a lithium ion battery using an iron phosphate-based material for the positive electrode and graphite for the negative electrode has a small change in OCV in a wide SOC region except for a part of the SOC region. In this region, the SOC estimation based on the OCV is difficult. Therefore, there is a technique that combines an SOC estimation method based on current integration and an SOC estimation method based on OCV (see Patent Document 1 below). Specifically, this conventional technique usually obtains an estimated value of SOC by an SOC estimation method based on current integration, and converts the estimated SOC value based on the current integration to OCV at a predetermined timing. This is a method of suppressing an SOC integration error based on current integration by shifting to an estimated SOC value.

JP 2010-283922 A

  However, conventionally, the presence or absence (large or small) of an error between the estimated value of SOC based on current integration or OCV and the actual value of SOC, that is, the reliability of the estimated value of SOC is not considered. For this reason, the above-described conventional technique has a problem that, when the predetermined timing is reached, the estimated value of the SOC based on the current integration is unreliably shifted to the estimated value of the SOC based on the OCV. Arise. As an SOC estimation method, there is a method of estimating the SOC based on the value of a variable element having a correlation with the SOC, such as voltage and temperature, in addition to the current. Even in these methods, an error may occur between the estimated value of the SOC and the actual value of the SOC, and the reliability is not considered.

  The present specification discloses a technique capable of determining the reliability of the estimated value of the SOC based on the value of the variable element having a correlation with the SOC and different from the OCV.

  The state-of-charge reliability determination device disclosed in the present specification is such that an open-circuit voltage change rate, which is a change amount of the open-circuit voltage per unit change amount of the charge state, is relatively A voltage detection unit that detects a voltage of a power storage element in which a plurality of charged state regions including a high change region that is high and a low change region in which the open-circuit voltage change rate is relatively low, and a control unit, The control unit acquires a value of a variable element of the power storage element having a correlation with the state of charge and different from the open circuit voltage, and based on the acquired value of the variable element, the power storage element A charge state estimation process for estimating a charge state of the battery, an open circuit voltage measurement process for measuring an open circuit voltage of the power storage element based on a detection result of the voltage detector, and an estimated value of the charge state based on the value of the variable element. Genus Region determination process for determining whether an estimation region that is a region to be measured and a measurement region to which a measurement value of a charging state corresponding to the measurement value of the open circuit voltage is identical or not coincide with each other in the high change region And a reliability determination process that determines that the reliability of the estimated value of the state of charge is higher than that determined when the estimated area and the measurement area coincide with each other in the high-change area And a configuration for executing

  According to the invention disclosed by this specification, it is possible to determine the reliability of the estimated value of the SOC based on the value of the variable element that has a correlation with the SOC and is different from the OCV.

The block diagram which shows the electrical constitution of the charge condition reliability determination apparatus which concerns on one Embodiment. Graph showing OCV and SOC of secondary battery Flow chart showing integrated SOC estimation process The flowchart which shows the reliability determination process of SOC estimated value Flowchart showing SOC initial value determination processing A Flow chart showing current measurement correction processing Flowchart showing SOC initial value determination process B The flowchart which shows SOC initial value decision processing B1 The flowchart which shows SOC initial value decision processing B2 The flowchart which shows SOC initial value decision processing B3 Graph showing a specific example of this embodiment

  (Outline of this embodiment)

  The state-of-charge reliability determination device disclosed in the present specification is such that an open-circuit voltage change rate, which is a change amount of the open-circuit voltage per unit change amount of the charge state, is relatively A voltage detection unit that detects a voltage of a power storage element in which a plurality of charged state regions including a high change region that is high and a low change region in which the open-circuit voltage change rate is relatively low, and a control unit, The control unit acquires a value of a variable element of the power storage element having a correlation with the state of charge and different from the open circuit voltage, and based on the acquired value of the variable element, the power storage element A charge state estimation process for estimating a charge state of the battery, an open circuit voltage measurement process for measuring an open circuit voltage of the power storage element based on a detection result of the voltage detector, and an estimated value of the charge state based on the value of the variable element. Genus Region determination process for determining whether an estimation region that is a region to be measured and a measurement region to which a measurement value of a charging state corresponding to the measurement value of the open circuit voltage is identical or not coincide with each other in the high change region And a reliability determination process that determines that the reliability of the estimated value of the state of charge is higher than that determined when the estimated area and the measurement area coincide with each other in the high-change area And a configuration for executing

  In the change characteristic, when the measurement region to which the measurement value of the charging state corresponding to the measurement value of the open-circuit voltage belongs is a high-change region, the measurement value of the charge state corresponding to the measurement value of the open-circuit voltage is the low-change region. It is close to the actual state of charge compared to For this reason, the estimated area, which is the area to which the estimated value of the charging state based on the value of the variable element belongs, matches in the above measurement area and the high change area. It means close to the actual value of the state and high reliability. Therefore, this state-of-charge reliability determination apparatus determines that the reliability of the estimated value of the state of charge is higher when the estimation region and the measurement region match in the high change region than in the case where they do not match in the high change region. To do. Thereby, it is possible to determine the reliability of the estimated value of the SOC based on the value of the variable element having a correlation with the SOC and different from the open circuit voltage.

  In the charging state estimation device, when the control unit determines that the estimation region and the measurement region do not match in the region determination processing, the estimation region is separated from the measurement region in the reliability determination processing. The configuration may be such that the reliability of the estimated value of the state of charge is determined to be lower as it is higher.

  When it is determined in the region determination process that the estimation region and the measurement region do not match, the state of charge reliability determination device indicates that the reliability of the estimation value of the state of charge is lower as the estimation region is farther from the measurement region. judge. Thereby, the degree of reliability of the estimated value of the state of charge can be determined from the degree of separation between the estimation region and the measurement region.

  In the charging state estimation device, the control unit determines a charging state based on the value of the variable element on the condition that the estimation region and the measurement region are determined not to match in the high change region in the region determination process. It is also possible to perform a change process for changing the estimated value to a measured value of the state of charge corresponding to the measured value of the open circuit voltage in the change characteristic.

  This state-of-charge reliability determination device is configured to measure an open state voltage in a change characteristic based on a value of a variable element on condition that an estimated region and a measurement region are determined not to coincide with each other in a high change region. Change to the measured value of the state of charge corresponding to the value. In other words, on the condition that the reliability of the estimated value of the charging state is low, the estimated value is changed to the measured value of the charging state corresponding to the measured value of the open circuit voltage. Therefore, regardless of the reliability of the estimated value of the charged state, a wasteful change process is performed compared to the configuration in which the measured value is uniformly changed to the measured value of the charged state corresponding to the measured value of the open circuit voltage. Can be suppressed.

  In the charging state estimation device, when the control unit determines that the estimation region and the measurement region do not coincide with each other in the high change region in the region determination processing, the storage element is fully charged in the change processing. In the state, the estimated value of the charging state may be changed to a measured value of the charging state corresponding to the measured value of the open circuit voltage.

  When it is determined in the region determination process that the estimation region and the measurement region do not coincide with each other in the high-change region, the state-of-charge reliability determination device calculates an estimated value of the state of charge when the storage element is fully charged. Change to the measured value of the charge state corresponding to the measured value. Thereby, even when the open circuit voltage is in the plateau region at the time of determining the reliability of the estimated value of the state of charge, it can be reset with the correct SOC value.

  In the charging state estimation device, in the region determination process, the control unit further determines whether the estimation region is the high change region and the measurement region is the low change region, and In the reliability determination process, when it is determined that the estimation area is the high change area and the measurement area is the low change area, the larger the time difference from the previous execution of the change process, The structure which determines with the reliability of the estimated value of the said charging state being low may be sufficient.

  When it is determined that the estimation region is the high change region and the measurement region is the low change region, the charging state reliability determination device increases the charging time as the time difference from the previous execution of the change process increases. It is determined that the reliability of the estimated state value is low. Thereby, the reliability degree of the estimated value of the state of charge can be determined.

  The charging state estimation device includes a current detection unit that detects a charge / discharge current flowing through the power storage element, and the control unit integrates the current value detected by the current detection unit in the charging state estimation process, As the value of the variable element, the state of charge of the power storage element is estimated based on the integrated value. In the reliability determination process, the estimation region is the high change region, and the measurement region is the low change. If it is determined that the region is a region, the time difference from the previous execution time of the change process and the change amount of at least one of the integrated values from the previous execution time of the change process are larger, the charge state It may be determined that the reliability of the estimated value is low.

  This state-of-charge reliability determination apparatus integrates the current values detected by the current detector, and estimates the state of charge of the storage element based on the integrated value as the value of the variable element. In addition, when it is determined that the estimation area is a high change area and the measurement area is a low change area, the time difference from the previous execution of the change process and the previous change execution time It is determined that the reliability of the estimated value of the state of charge is lower as at least one change amount of the integrated value is larger. Thereby, the reliability degree of the estimated value of the state of charge based on the integrated value of the current value can be determined.

  In the charging state estimation device, in the region determination process, the control unit further determines whether the estimated value of the charging state based on the integrated value of the current value is the plurality of high change regions or the plurality of low change regions. When the measured value of the charging state corresponding to the measured value of the open circuit voltage is a value in a region different from the estimated value of the charged state, the estimated value of the charged state and the measured value of the charged state If the magnitude relationship is the same for a plurality of times, the change process is executed, and it is determined that the magnitude relationship is the same for a plurality of times, the current value The correction process which corrects the said current value in the direction which approaches the estimated value of the charging state based on the integrated value of the charging state to the measured value of the charging state corresponding to the measured value of the open circuit voltage may be performed.

  When the estimated value of the charging state based on the integrated value of the current value and the measured value of the charging state corresponding to the measured value of the open circuit voltage are the same, if the number of consecutive times is consecutive, the detected current in the current detection unit May be off. Therefore, this charging state reliability determination device determines the current value when it is determined that the magnitude relationship continues multiple times even if the estimated value of the charging state is replaced with the measured value when the charging state is fully charged or fully discharged. The current value in the current detection unit is corrected so that the estimated value of the charging state based on the integrated value of the current value approaches the measured value of the charging state corresponding to the measured value of the open circuit voltage. Thereby, it can suppress that the determination accuracy of reliability falls by abnormality of an electric current detection part.

  In the state of charge estimation device, the control unit further determines whether the estimation region is the low change region and the measurement region is the high change region in the region determination process, In the reliability determination process, when it is determined that the estimation region is the low change region and the measurement region is the high change region, the estimated value of the charging state based on the value of the variable element, and the release The configuration may be such that the larger the difference from the measured value of the charge state corresponding to the measured value of the voltage, the lower the reliability of the estimated value of the charged state.

  When it is determined that the estimation region is a low change region and the measurement region is a high change region, this state of charge reliability determination device measures the estimated value of the charge state based on the value of the variable element and the open circuit voltage. It is determined that the reliability of the estimated value of the state of charge is lower as the difference from the measured value of the state of charge corresponding to the value is larger. When the measurement region is a high change region, the measured value of the charging state corresponding to the measured value of the open circuit voltage approximates the actual value of the charging state, so the reliability of the estimated value of the charging state directly depends on the above difference. The degree can be determined.

  In addition, a power storage device including a power storage element and a charged state reliability determination device may be used.

  The invention disclosed in this specification can be realized in various modes such as a control device, a control method, a computer program for realizing the functions of these methods or devices, and a recording medium on which the computer program is recorded. Can do.

<One Embodiment>
An embodiment will be described with reference to FIGS. The battery pack 1 of the present embodiment is mounted on, for example, an electric vehicle or a hybrid vehicle (hereinafter simply referred to as an automobile), and supplies power to a power source that operates with electric energy.

(Battery pack configuration)
As shown in FIG. 1, the battery pack 1 includes an assembled battery 2 and a battery management device (hereinafter referred to as “BMS”) 3. The assembled battery 2 is an example of a power storage element, and has a configuration in which a plurality of battery cells C are connected in series. Each battery cell C is a rechargeable secondary battery, specifically, a lithium ion battery using an iron phosphate-based material for the positive electrode and graphite for the negative electrode. The battery pack 1 is an example of a power storage device, and the BMS 3 is an example of a charged state reliability determination device.

  The assembled battery 2 is electrically connected via a wiring 4 and a switch 42 to a charging device 40 provided inside or outside the automobile or a load 41 such as a power source provided inside the automobile. The charging device 40 receives power supply from an external power source (not shown) and charges the assembled battery 2.

  The BMS 3 includes a control unit 31, an analog-digital converter (hereinafter referred to as ADC) 32, a current sensor 33, and a voltage sensor 34. The control unit 31 includes a central processing unit (hereinafter referred to as a CPU) 35 and a memory 36 such as a ROM or a RAM. Various programs (including an SOC estimation program) for controlling the operation of the BMS 3 are stored in the memory 36, and the CPU 35 executes an SOC estimation process to be described later according to the program read from the memory 36. Control each part. The control unit 31 is an example of a control unit, and the voltage sensor 34 is an example of a voltage detection unit.

  The current sensor 33 detects the charging current that flows from the charging device 40 to the assembled battery 2 during charging and the current value I [A] of the discharging current that flows from the assembled battery 2 to the load 41 during discharging. A corresponding analog detection signal SG1 is transmitted to the ADC 32. Hereinafter, when it is not necessary to distinguish between the charging current and the discharging current, it is referred to as charging / discharging current. The voltage sensor 34 is connected to both ends of each battery cell C of the assembled battery 2, detects a voltage value V [V] which is a terminal voltage of the battery cell C, and an analog detection signal corresponding to the detected voltage value V SG2 is transmitted to the ADC 32. The voltage sensor 34 can detect an accurate voltage value V in which the influence of the wiring resistance of the wiring 4 is suppressed by directly detecting the terminal voltage without using the wiring 4.

  The ADC 32 converts the detection signals SG1 and SG2 transmitted from the current sensor 33 and the voltage sensor 34 from analog signals to digital signals, and transmits digital data indicating the current value I and the voltage value V to the control unit 31. Then, the control unit 31 stores the digital data in the memory 36.

(OCV-SOC curve of secondary battery)
In FIG. 2, the OCV-SOC curve of the battery cell C is shown by a solid line. The OCV-SOC curve indicates the change characteristic (correlation) between the OCV and the SOC of the battery cell C. The OCV on the OCV-SOC curve is a terminal voltage of the battery cell C when the voltage of the battery cell C is in a stable state, such as when a state in which no charge / discharge current is flowing continues. The terminal voltage of the battery cell C when the voltage change amount per unit time of the battery cell C is equal to or less than the specified amount. The prescribed amount can be determined in advance by the specification of the battery cell C, a predetermined experiment, or the like. As shown in FIG. 1, data relating to the OCV-SOC curve is stored in the memory 36. Moreover, the terminal voltage of the battery cell C is an example of a fluctuation element.

  According to the OCV-SOC curve of the battery cell C shown in the figure, the change region in which the terminal voltage of the battery cell C can change includes a plurality of change regions having different OCV change rates. The OCV change rate is an OCV change amount per unit change amount of the SOC, and is an example of an open circuit voltage change rate. Specifically, the different change regions include a steep change region EH (EH1, EH2, EH3) having a relatively high OCV change rate and a minute change region EL (EL1, EL2) having a relatively low OCV change rate. It is included. The steep change region EH is an example of a high change region, and the minute change region EL is an example of a low change region.

  In the example of the figure, in the steep change region EH, the change region where the SOC value is about 0% to about 30% is called the first steep change region EH1, and the change of the SOC value is about 65% to about 68%. The region is referred to as a second steep change region EH2, and the voltage region having an SOC value of about 94% to about 100% is referred to as a third steep change region EH3.

  The OCV change rate in the first steep change region EH1 and the OCV change rate in the second steep change region EH2 are different from each other. Specifically, the OCV change rate in the second steep change region EH2 is It is slightly higher than the OCV change rate in the one steep change region EH1. Further, the OCV change rate in the second steep change region EH2 and the OCV change rate in the third steep change region EH3 are different from each other. Specifically, the OCV change rate in the third steep change region EH3 is the second steep change region EH3. It is slightly higher than the OCV change rate in the steep change region EH2.

  On the other hand, in the example shown in the figure, in the minute change region EL, the change region having the SOC value of about 30% to about 65% is called the first minute change region EL1, and the SOC value is about 68% to about 94%. This area is referred to as a second minute change area EL2. The OCV change rate in each minute change region EL is different from each other. Specifically, the OCV change rate in the first minute change region EL1 is slightly higher than the OCV change rate in the second minute change region EL2. . The level of the OCV change rate can be determined, for example, depending on whether or not the SOC estimation error with respect to the predetermined OCV detection error is within an allowable range.

  The BMS 3 selects a representative cell from the battery cell C of the assembled battery 2, estimates the SOC from the voltage of the representative cell, and sets the SOC as the SOC of the assembled battery 2. Specifically, the terminal voltage values of the battery cells C are compared, and the battery cell C having the lowest terminal voltage value is set as the representative cell. As another method, a battery cell whose terminal voltage is a median value may be used as a representative cell. Or BMS3 may calculate the average value of a terminal voltage value for every 2-3 battery cells C, for example, and may estimate SOC from the lowest average value. Alternatively, the SOC may be estimated from an average value obtained by dividing the total voltage of the assembled battery 2 by the number of cells. Alternatively, the SOC may be estimated by preparing an OCV-SOC curve corresponding to the total voltage of the assembled battery 2. In this way, various methods can be taken. Hereinafter, a cell used for SOC estimation is referred to as a representative cell D.

(Determining the reliability of the estimated SOC value)
As described above, in the SOC estimation method based on current integration, if current integration is performed for a long time due to, for example, a measurement error of a current sensor, an error between the estimated value of SOC based on the current integration and the actual value of SOC occurs. There is a risk that it will accumulate and become larger. Therefore, the error due to current integration is reset by using the SOC estimation method based on OCV. The SOC value based on the OCV is an example of a measured value of the state of charge.

  However, in the SOC estimation method based on the OCV, in the change characteristic of the OCV with respect to the SOC, the SOC estimation based on the OCV is performed in a region where the open circuit voltage change rate that is the change amount of the OCV per unit change amount of the SOC is relatively low. There is a demerit such that an error between the value and the actual value of the SOC increases.

  For example, as shown in FIG. 2, when the terminal voltage value of the representative cell D is 3.27 V (point B), there is an inclination of the OCV-SOC curve, so the SOC may be estimated to be about 24%. I can do it.

  However, when the terminal voltage value of the representative cell D is 3.34 V (point C), there is almost no inclination of the OCV-SOC curve, so the SOC is only about 68% to about 94%. It cannot be estimated.

  For this reason, when the terminal voltage value of the representative cell D is at the point C, the SOC cannot be estimated based on the OCV, and the error due to current integration cannot be reset.

  Therefore, by determining whether the estimated SOC value based on the current integration and the estimated SOC value based on the OCV belong to the steep change region EH or the minute change region EL, the estimated SOC value based on the current integration is determined. Judge reliability. As a result, when the reliability is low, for example, charging the assembled battery 2 until it is fully charged and resetting the SOC to 100% can suppress the inconvenience that the error due to current integration cannot be reset. it can.

(SOC estimation process flow)
(1) Accumulated SOC estimation process For example, the CPU 35 uses the current value detected by the current sensor 33 as a trigger when charging / discharging of the assembled battery 2 is started, for example, when the driver turns on a car key. And SOC estimation processing based on current integration is executed. The SOC based on current integration is hereinafter referred to as integration SOC, and the value of each integration SOC is referred to as current integration SOC value. As shown in FIG. 3, first, the CPU 35 reads the current accumulated SOC value stored in the memory 36 (S1). And CPU35 judges whether charging / discharging of the assembled battery 2 stopped (S2).

  When determining that charging / discharging of the assembled battery 2 has not stopped (S2: NO), the CPU 35 integrates the current of the charging / discharging current based on the detection signal SG1 from the current sensor 33 (S3). The CPU 35 calculates a value of ΔSOC from the integrated value (S4), and sets a value calculated by adding the value of ΔSOC to the current integrated SOC value read from the memory 36 as a new current integrated SOC value (S5). Then, the CPU 35 returns to S2 and determines whether charging / discharging of the assembled battery 2 is stopped. The charge / discharge current is an example of a variable element, and the integrated SOC and the current integrated SOC value are examples of an estimated value of the state of charge.

  When CPU 35 determines that charging / discharging of assembled battery 2 has stopped (S2: YES), CPU 35 stores the current integrated SOC value in memory 36 (S6). And CPU35 complete | finishes the estimation process of integrated SOC. In addition, various known techniques can be used to estimate the SOC. Note that the process of S5 is an example of a charge state estimation process.

  Further, when there is a request from an external device or a host electronic control unit, the CPU 35 transmits the current integrated SOC value at that time as the current SOC value.

  Note that “the charging / discharging of the assembled battery 2 has stopped” is not limited to the case where the charging / discharging of the assembled battery 2 is completely stopped (a state in which the switch 42 is opened), but is assembled via the switch 42. Even when a standby current flows through the load 41 to which the battery 2 is connected (for example, less than several mA), a dark current flows through the BMS 3 (for example, less than several hundred μA).

  On the other hand, while the power is supplied to the BMS 3, the CPU 35 constantly executes the SOC estimation value reliability determination process described below.

(2) SOC Estimated Value Reliability Determination Processing As shown in FIG. 4, the CPU 35 first determines whether charging / discharging of the assembled battery 2 has stopped (S11). When it is determined that charging / discharging of the assembled battery 2 has not stopped (S11: NO), the CPU 35 stands by, and when it is determined that charging / discharging of the assembled battery 2 has been stopped (S11: YES), the CPU 35 is predetermined. It is determined whether time (for example, 2 hours) has elapsed (S12). The predetermined time is a time from when charging / discharging of the assembled battery 2 is stopped to the time when the terminal voltage of the battery cell C is stabilized. The predetermined time can be determined by experiment or experience.

  When the CPU 35 determines that the predetermined time has not elapsed (S12: NO), the CPU 35 returns to S11. When the CPU 35 determines that the predetermined time has elapsed (S12: YES), the CPU 35 detects from the voltage sensor 34. Based on the signal SG2, the terminal voltage value of the representative cell D is detected (S13). Since the CPU 35 detects the terminal voltage value of the representative cell D after a predetermined time has elapsed, the terminal voltage value becomes substantially equal to the OCV of the representative cell D. That is, it can be said that the processing of S12 and S13 detects the OCV of the representative cell D. Therefore, the process of S12 and S13 is an example of an open circuit voltage measurement process.

  Then, the CPU 35 reads the voltage measurement SOC value stored in the memory 36 based on the terminal voltage value (S14). The voltage measurement SOC value refers to the SOC value calculated by the CPU 35 from the SOC-OCV curve based on the terminal voltage of the representative cell D. The voltage measurement SOC value is an example of a measurement value of the state of charge.

  Thereafter, the CPU 35 reads the current integrated SOC value stored in the memory 36 (S15), and determines whether or not the current integrated SOC value is in the second steep change region EH2 (S16). If the CPU 35 determines that the current integrated SOC value is in the second steep change region EH2 (S16: YES), the CPU 35 executes an SOC initial value determination process A described later (S17), and the current integrated SOC value is the second steep change region EH2. When it determines with it not being in change area EH2 (S16: NO), the SOC initial value determination process B mentioned later is performed (S18). Then, the reliability of the estimated SOC value is determined in the SOC initial value determination process. In this specification, regarding the current integrated SOC value, the reset current integrated SOC value after reliability determination is particularly referred to as an SOC initial value. When the process of S16 is YES, the estimated area in the present invention is the second steep change area EH2.

(2-1) SOC initial value determination processing A (when the current integrated SOC value is in the second steep change region)
In FIG. 4, the SOC initial value determination process A is estimated according to the terminal voltage value of the representative cell D detected in S <b> 13 when the CPU 35 determines that the current integrated SOC value is in the second steep change region (S <b> 16: YES). This is a process for determining the reliability of the current integrated SOC value according to the change region to which the SOC value (voltage measurement SOC value) belongs.

  As shown in FIG. 5, first, the CPU 35 determines whether or not the voltage measurement SOC value is in the second steep change region (S21). If the CPU 35 determines that the voltage measurement SOC value is in the second steep change region (S21: YES), the current integrated SOC value and the voltage measurement SOC value are in the same region, and the range of the SOC value is about Since it is in the second steep change region EH2 that is as narrow as 65% to about 68%, the current integrated SOC value is determined to be highly reliable (S22). Since the OCV value is in the second steep change region (EH2), the CPU 35 sets the voltage measurement SOC value as a new SOC initial value (S23).

  In this case, since the reliability determination is highly reliable, the current integrated SOC value may be set as a new SOC initial value. However, when the OCV is in the steep change region, the voltage measurement SOC value is set as the new SOC initial value. (S23) is preferable. Note that the process of S21 is an example of an area determination process, and the process of S22 is an example of a reliability determination process. When the process of S21 is YES, the measurement area in the present invention is the second steep change area.

  On the other hand, when the CPU 35 determines that the voltage measurement SOC value is not in the second steep change region (S21: NO), the CPU 35 has the voltage measurement SOC value in the first minute change region EL1 or the second minute change region EL2. It is determined whether or not (S24). When the CPU 35 determines that the voltage measurement SOC value is in the first minute change region EL1 or the second minute change region EL2 (S24: YES), the current integrated SOC value and the voltage measurement SOC value are in different regions. The integrated SOC value is determined to be low reliability (S110).

  The process of S24 is an example of a region determination process, and the process of S110 is an example of a reliability determination process. However, since the voltage measurement SOC value is in the minute change region EL, the CPU 35 cannot accurately estimate the SOC value.

  Therefore, in order to accurately estimate the SOC value, for example, the CPU 35 fully charges the assembled battery 2 and sets the SOC value to 100% (S120). Then, the CPU 35 sets the accurate SOC value as the SOC initial value by setting the SOC initial value to 100% (S130). Specifically, the assembled battery 2 is charged, and when the open circuit voltage value becomes a value corresponding to a predetermined full charge, the current integrated SOC value is set as 100%. Further, a current measurement correction process to be described later is executed (S400).

  When the CPU 35 determines that the voltage measurement SOC value is not in the first minute change region EL1 or the second minute change region EL2 (S24: NO), that is, the voltage measurement SOC value is the first steep change region EH1 or the third steep change region EL2. If it is determined that the current value is in the change region EH3, the current integrated SOC value and the voltage measurement SOC value are in different regions, but the voltage measurement SOC value is a steep change region EH in which the CPU 35 can accurately estimate the SOC value. Therefore, the reliability is not determined (S160), and the SOC is estimated according to the terminal voltage value detected in S13 (S170).

  Then, the CPU 35 sets the voltage measurement SOC value as a new SOC initial value (S180), and ends the SOC initial value determination processing A. Although the reliability is not determined in S160, the reliability may be determined. In this case, although it is determined that the reliability is once low, the current integrated SOC value is changed (reset) to the voltage measurement SOC value immediately after that. Further, the processes of S180 and S130 are an example of a change process.

(2-2) Current Measurement Correction Process The current measurement correction process is a process in which the CPU 35 corrects the current measurement value of the current sensor when a predetermined execution condition is satisfied. The predetermined execution condition is that when the reset of the current integrated SOC value is performed a plurality of times within a time continuous period, the current integrated SOC value and the voltage measurement SOC are determined in a plurality of reliability determination processes. The CPU 35 determines that the current integration SOC value and the voltage measurement SOC value are the same in a plurality of times that the values are in different regions and the magnitude relationship between the voltage measurement SOC value is the same. Note that “continuous multiple times” can be set as appropriate, for example, three consecutive times.

  Various methods can be used to determine whether the current integrated SOC value and the voltage measured SOC value are in different regions and whether the magnitude relationship between the current integrated SOC value and the voltage measured SOC value is the same. However, in this embodiment, it is implemented by a simple method.

  Specifically, as shown in FIGS. 4 to 6, first, it is confirmed that the current integrated SOC value is in the second steep change region (S16 in FIG. 4), and then the voltage measurement SOC value is in the minute change region. (S24 in FIG. 5). Thereafter, it is determined whether or not the voltage measurement SOC value is in the same minute change region as in the previous reliability determination (S34 in FIG. 6) with the reset of the SOC (S130 in FIG. 5) interposed therebetween.

  As shown in FIG. 5 and the like, when the CPU 35 determines that the current integrated SOC value is low reliability in order to accurately estimate the SOC value, for example, the battery pack 2 is fully charged and the SOC value is determined. Is 100%, and the current integrated SOC value is reset.

  However, in spite of resetting the current integrated SOC value, the CPU 35 is in a region where the current integrated SOC value and the voltage measurement SOC value are different from each other in the reliability determination process, and the current integrated SOC value and the voltage measurement. It can be determined that the measurement error of the current measurement has increased because the SOC value has the same magnitude relationship for a plurality of times. That is, the CPU 35 can determine that the measured value of the current sensor 33 is deviated from the actual value.

  Therefore, as shown in FIG. 6, when the CPU 35 determines that the execution condition is satisfied (S34: YES), the current sensor 33 sets the current value I to a value larger or smaller than the charge / discharge current that actually flows. It is determined that the current is detected, and the current value I detected by the current sensor 33 is corrected (S35).

  For example, after resetting the current integrated SOC value, at the time of discharging, the current integrated SOC value is in the second steep change region EH2, and the voltage measurement SOC value is in the first minute change region EL1 (that is, more than the current integrated SOC value). If the determination of (small value) continues with a plurality of resets, the CPU 35 performs the following processing. The CPU 35 determines that the current value I (discharge current value I) detected by the current sensor 33 is smaller than the actually flowing discharge current value, and corrects the discharge current detected by the current sensor 33 to be large. . When the current on the discharge side and the charge side is measured with one current sensor, correction such as adjusting the zero point of the current sensor is performed.

  Then, the CPU 35 ends the current measurement correction process. The process of S35 is an example of a correction process.

  When determining that the execution condition is not satisfied (S34: NO), the CPU 35 ends the current measurement correction process as it is.

(2-3) SOC initial value determination process B (when the current integrated SOC value is not in the second steep change region)
In the SOC initial value determination process B, when the CPU 35 determines that the current integrated SOC value is not in the second steep change region EH2 (S15: NO), the SOC initial value determination processing B is performed according to the change region to which the current integrated SOC value and the voltage measurement SOC value belong. Thus, the SOC initial value is determined. Specifically, as shown in FIG. 7 and the like, the CPU 35 first determines in which change region the current integrated SOC value is present (S41, S50), and then the voltage as shown in FIGS. It is determined which change region the measured SOC value is in (S42, S45, S51, S54, S59).

  First, the CPU 35 determines whether or not the current integrated SOC value is in the first minute change region EL1 (S41).

(I) When the current integrated SOC value is in the first minute change region EL1 When the CPU 35 determines that the current integrated SOC value is in the first minute change region EL1 (S41: YES), the SOC initial value shown in FIG. The determination process B1 is executed (S500). In this SOC initial value determination process B1, the CPU 35 determines whether or not the voltage measurement SOC value is in the first minute change region EL1 (S42).

  When the CPU 35 determines that the voltage measurement SOC value is in the first minute change region EL1 (S42: YES), the current integrated SOC value and the voltage measurement SOC value are in the same first minute change region EL1. However, the first minute change region EL1 has a very wide SOC value range of about 30% to about 65%, and the current integrated SOC value and the voltage measurement SOC value can be close to the SOC value. On the other hand, there may be a completely different SOC value.

  Therefore, the CPU 35 does not determine the reliability of the current integrated SOC value (S210), sets the current integrated SOC value calculated in S5 to a new SOC initial value (S220), and ends the SOC initial value determination process B1. Then, the CPU 35 ends the SOC estimation value reliability determination process.

  When determining that the voltage measurement SOC value is not in the first minute change region EL1 (S42: NO), the CPU 35 determines whether the voltage measurement SOC value is in the second minute change region EL2 (S45). If the CPU 35 determines that the voltage measurement SOC value is in the second minute change region EL2 (S45: YES), the current integrated SOC value and the voltage measurement SOC value are in different change regions, and the voltage measurement SOC value is Since it is in the second minute change region EL2, the current integrated SOC value is determined to be low reliability (S110). However, since the voltage measurement SOC value is in the minute change region EL, the CPU 35 cannot accurately estimate the SOC value.

  Therefore, in order to accurately estimate the SOC value, for example, the CPU 35 fully charges the assembled battery 2 and sets the SOC value to 100% (S120). Then, the CPU 35 sets the accurate SOC value as the SOC initial value by setting the SOC initial value to 100% (S130). Note that the CPU 35 only needs to be able to accurately estimate the SOC value. For example, the assembled battery 2 is completely discharged to set the SOC value to 0%. Then, the CPU 35 may set an accurate SOC value as the SOC initial value by setting the SOC initial value to 0%.

  Then, the CPU 35 executes the above-described current measurement correction process (S400), and ends the SOC initial value determination process B1. Then, the CPU 35 ends the SOC estimation value reliability determination process.

  On the other hand, when the CPU 35 determines that the voltage measurement SOC value is not in the second minute change region EL2 (S45: NO), that is, when it is determined that the voltage measurement SOC value is in the steep change region EH, the current integrated SOC value However, since the voltage measurement SOC value is in the steep change region EH in which the CPU 35 can accurately estimate the SOC value, the reliability is not determined (S160).

  Then, the CPU 35 estimates the SOC according to the terminal voltage value detected in S13 (S170), sets the voltage measurement SOC value to a new SOC initial value (S180), and ends the SOC initial value determination process B1. Then, the CPU 35 ends the SOC estimation value reliability determination process. Although the reliability is not determined in S160, the reliability may be determined. In this case, although it is determined that the reliability is once low, the current integrated SOC value is changed (reset) to the voltage measurement SOC value immediately after that.

(Ii) When the current integrated SOC value is in the second minute change region EL2 When the CPU 35 determines that the current integrated SOC value is not in the first minute change region EL1 (S41: NO), the current integrated SOC value is second. It is determined whether or not it is in the minute change region EL2 (S50). When determining that the current integrated SOC value is in the second minute change region EL2 (S50: YES), the CPU 35 executes the SOC initial value determination process B2 shown in FIG. 9 (S600). In this SOC initial value determination process B2, the CPU 35 determines whether or not the voltage measurement SOC value is in the second minute change region EL2 (S51).

  When the CPU 35 determines that the voltage measurement SOC value is in the second minute change region EL2 (S51: YES), the current integrated SOC value and the voltage measurement SOC value are in the same second minute change region EL2. However, the second minute change region EL2 has an extremely wide SOC value range of about 68% to about 94%, and the current integrated SOC value and the voltage measurement SOC value can be close to the SOC value. On the other hand, there may be a completely different SOC value.

  Therefore, the CPU 35 does not determine the reliability of the current integrated SOC value (S210), sets the current integrated SOC value calculated in S5 to a new SOC initial value (S220), and ends the SOC initial value determination process B2. Then, the CPU 35 ends the SOC estimation value reliability determination process.

  When determining that the voltage measurement SOC value is not in the second minute change region EL2 (S51: NO), the CPU 35 determines whether the voltage measurement SOC value is in the first minute change region EL1 (S54). When the CPU 35 determines that the voltage measurement SOC value is in the first minute change region EL1 (S54: YES), the current integrated SOC value and the voltage measurement SOC value are in different change regions, and the voltage measurement SOC value is Since it is in the first minute change region EL1, the current integrated SOC value is determined to be low reliability (S110). However, since the voltage measurement SOC value is in the minute change region EL, the CPU 35 cannot accurately estimate the SOC value.

  Therefore, in order to accurately estimate the SOC value, for example, the CPU 35 fully charges the assembled battery 2 and sets the SOC value to 100% (S120). Then, the CPU 35 sets the accurate SOC value as the SOC initial value by setting the SOC initial value to 100% (S130). Note that the CPU 35 only needs to be able to accurately estimate the SOC value. For example, the assembled battery 2 is completely discharged to set the SOC value to 0%. Then, the CPU 35 may set an accurate SOC value as the SOC initial value by setting the SOC initial value to 0%.

  Then, the CPU 35 executes the above-described current measurement correction process (S400), and ends the SOC initial value determination process B2. Then, the CPU 35 ends the SOC estimation value reliability determination process.

  On the other hand, if the CPU 35 determines that the voltage measurement SOC value is not in the first minute change region EL1 (S54: NO), that is, if it is determined that the voltage measurement SOC value is in the steep change region EH, the current integrated SOC value However, since the voltage measurement SOC value is in the steep change region EH in which the CPU 35 can accurately estimate the SOC value, the reliability is not determined (S160).

  Then, the CPU 35 estimates the SOC according to the terminal voltage value detected in S13 (S170), sets the voltage measurement SOC value to a new SOC initial value (S180), and ends the SOC initial value determination process B2. Then, the CPU 35 ends the SOC estimation value reliability determination process. Although the reliability is not determined in S160, the reliability may be determined. In this case, although it is determined that the reliability is once low, the current integrated SOC value is changed (reset) to the voltage measurement SOC value immediately after that.

(Iii) When the current integrated SOC value is in the first steep change region EH1 or the third steep change region EH3 When the CPU 35 determines that the current integrated SOC value is not in the second minute change region EL2 (S50: NO), That is, when it is determined that the current integrated SOC value is in the first steep change region EH1 or the third steep change region EH3, the SOC initial value determination process B3 shown in FIG. 10 is executed (S700). In this SOC initial value determination process B3, the CPU 35 determines whether or not the voltage measurement SOC value is in the first minute change region EL1 or the second minute change region EL2 (S59).

  When the CPU 35 determines that the voltage measurement SOC value is in the first minute change region EL1 or the second minute change region EL2 (S59: YES), the current integrated SOC value and the voltage measurement SOC value are in different change regions, In addition, since the voltage measurement SOC value is in the first minute change region EL1 or the second minute change region EL2, it is determined that the current integrated SOC value has low reliability (S110). However, since the voltage measurement SOC value is in the minute change region EL, the CPU 35 cannot accurately estimate the SOC value.

  Therefore, in order to accurately estimate the SOC value, for example, the CPU 35 fully charges the assembled battery 2 and sets the SOC value to 100% (S120). Then, the CPU 35 sets the accurate SOC value as the SOC initial value by setting the SOC initial value to 100% (S130). Note that the CPU 35 only needs to be able to accurately estimate the SOC value. For example, the assembled battery 2 is completely discharged to set the SOC value to 0%. Then, the CPU 35 may set an accurate SOC value as the SOC initial value by setting the SOC initial value to 0%.

  Then, the CPU 35 executes the current measurement correction process described above (S400), and ends the SOC initial value determination process B3. Then, the CPU 35 ends the SOC estimation value reliability determination process.

  On the other hand, if the CPU 35 determines that the voltage measurement SOC value is not in the first minute change region EL1 or the second minute change region EL2 (S59: NO), that is, the voltage measurement SOC value is the first steep change region EH1, or When it is determined that the second steep change region EH2 or the third steep change region EH3 is present, the following processing is executed.

  Although the current integrated SOC value and the voltage measurement SOC value are in different change regions, the voltage measurement SOC value is in the steep change region EH in which the CPU 35 can accurately estimate the SOC value. (S160), the SOC is estimated according to the terminal voltage value detected in S13 (S170), the voltage measurement SOC value is set to a new SOC initial value (S180), and the SOC initial value determination process B3 is terminated. Then, the CPU 35 ends the SOC estimation value reliability determination process.

  Next, it is determined whether the estimated SOC value based on current integration (current integrated SOC value) and the estimated SOC value based on OCV (voltage measurement SOC value) belong to the steep change region EH or the minute change region EL. The effect of determining the reliability of the estimated SOC value based on the current integration will be described with reference to FIGS.

(Case 1)
As shown in FIG. 2, the current integrated SOC value of the representative cell D at a certain point in time is about 65% (on the OCV-SOC curve, point T in the second steep change region EH2, S16: YES), and the OCV value is Case 1 is set when the voltage measurement SOC value is about 67% and is in the second steep change region EH2 (point A) (S21: YES) at about 3.33V.

  In case 1, the current integrated SOC value and the voltage measurement SOC value are both in the same change region, and the range of the SOC value is in the narrow second steep change region EH2 of about 63% to about 68%. The current integrated SOC value is determined to be highly reliable (S22).

  Here, since the value of OCV is in the steep change region (EH2), the CPU 35 sets the voltage measurement SOC value as a new SOC initial value (S23). Since the current integrated SOC value and the voltage measurement SOC value are in the same steep change region and the error is only 5% at the maximum, the current integrated SOC value may be set as a new SOC initial value.

(Case 2)
Further, as shown in FIG. 2, the current integrated SOC value of the representative cell D at a certain point in time is about 65% (on the OCV-SOC curve, point T in the second steep change region EH2, S16: YES), and the OCV Case 2 is a case where the value is about 3.27 V, the voltage measurement SOC value is about 24% and is in the first steep change region EH1 (point B) (S24: NO).

  In Case 2, the current integrated SOC value and the voltage measured SOC value are in different change regions, and the difference between the current integrated SOC value and the voltage measured SOC value is about 41%. However, since the voltage measurement SOC value is in the first steep change region EH1 in which the CPU 35 can accurately estimate the SOC value, the CPU 35 does not determine the reliability of the current integrated SOC value (S160). Then, the CPU 35 sets the voltage measurement SOC value as a new SOC initial value (S180).

(Case 3)
Further, as shown in FIG. 2, the current integrated SOC value of the representative cell D at a certain point in time is about 65% (on the OCV-SOC curve, point T in the second steep change region EH2, S16: YES), and the OCV Case 3 is determined when the value is about 3.34 V and the voltage measurement SOC value is any value of about 68% to about 94% in the second minute change region EL2 (range C) (S24: YES).

  In case 3, since the current integrated SOC value and the voltage measurement SOC value are in different change regions, the CPU 35 determines that the current integrated SOC value is low reliability (S110). However, since the voltage measurement SOC value is any one of about 68% to about 94%, the CPU 35 cannot accurately estimate the SOC value.

  Therefore, in order to accurately estimate the SOC value, for example, the CPU 35 fully charges the assembled battery 2 and sets the SOC value to 100% (S120). Then, the CPU 35 sets the accurate SOC value as the SOC initial value by setting the SOC initial value to 100% (S130).

(Case 4)
Further, as shown in FIG. 11, the current integrated SOC value of the representative cell D at a certain point in time is about 45% (on the OCV-SOC curve, point D of the first minute change region EL1, S41: YES), and the OCV Case 4 is determined when the value is about 3.34 V and the voltage measurement SOC value is any value between about 68% and about 94% in the second minute change region EL2 (range C) (S45: YES).

  In case 4, since the current integrated SOC value and the voltage measurement SOC value are in different change regions, the CPU 35 determines that the current integrated SOC value is low reliability (S110). However, since the voltage measurement SOC value is any one of about 68% to about 94%, the CPU 35 cannot accurately estimate the SOC value.

  Therefore, in order to accurately estimate the SOC value, for example, the CPU 35 fully charges the assembled battery 2 and sets the SOC value to 100% (S120). Then, the CPU 35 sets the accurate SOC value as the SOC initial value by setting the SOC initial value to 100% (S130).

(Case 5)
Further, as shown in FIG. 11, the current integrated SOC value of the representative cell D at a certain point in time is about 87% (on the OCV-SOC curve, point E in the second minute change region EL2, S50: YES), and the OCV Case 5 is a case where the value is about 3.34 V and the voltage measurement SOC value is any value of about 68% to about 94% and is in the second minute change region EL2 (range C) (S51: YES).

  In case 5, the current integrated SOC value and the voltage measurement SOC value are in the same second minute change region EL2. However, in the second minute change region EL2, the possible range of the SOC value is extremely wide, about 68% to about 94%, and the current integrated SOC value and the voltage measurement SOC value can be the same about 87%. On the other hand, there may be a completely different SOC value.

  Therefore, the CPU 35 does not determine the reliability of the current integrated SOC value (S210), and sets the current integrated SOC value as it is as a new SOC initial value (S220).

(Effect of this embodiment)
In the present embodiment, whether the estimated SOC value based on current integration (current integrated SOC value) or the estimated SOC value based on OCV (voltage measurement SOC value) belongs to the steep change region EH or the minute change region EL. And the reliability of the estimated value of the SOC based on the current integration is determined. As a result, the inconvenience that the error due to current integration cannot be reset can be suppressed.

<Other embodiments>
The technology disclosed in the present specification is not limited to the embodiments described with reference to the above description and drawings, and includes, for example, the following various aspects.

  In the said embodiment, the control unit 31 which has one CPU35 was mentioned as an example as an example of a control part. However, the control unit is not limited thereto, and includes a configuration including a plurality of CPUs, a configuration including hardware circuits such as an application specific integrated circuit (ASIC) and a field-programmable gate array (FPGA), and both hardware circuits and CPUs. The structure provided with may be sufficient. For example, a configuration in which at least two of the area determination process, the condition setting process, and the estimation process are executed by separate CPUs and hardware circuits may be used.

  In the above embodiment, an example of the SOC estimation program stored in the memory 36 having the RAM or ROM is taken as an example. However, the SOC estimation program is not limited to this, and may be a non-volatile memory such as a hard disk device or a flash memory, or a storage medium such as a CD-R.

  In the above embodiment, an assembled battery is taken as an example of the power storage element. However, the present invention is not limited thereto, and the power storage element may be a single battery, a plurality of cells connected in series, or a parallel connection, and the number of cells can be changed as appropriate. The power storage element is not limited to an iron phosphate lithium ion battery, but may be another secondary battery such as a manganese lithium ion battery or a lead battery. Furthermore, the power storage element is not limited to a secondary battery, and may be a capacitor.

  In the said embodiment, charging / discharging electric current was mentioned as an example as an example of a variable element. However, the present invention is not limited to this, and the variable element may be the battery temperature, the internal resistance of the battery, the deterioration rate of the internal resistance, the charge / discharge time, or the like.

  In the above embodiment, the CPU 35 is configured to determine whether the reliability determination of the current integrated SOC value is high reliability or low reliability. However, the present invention is not limited to this, and the CPU 35 may have a configuration in which a degree is determined in reliability determination. In this configuration, the CPU 35 measures the time between the previous reliability determination process and the current reliability determination process. If it is determined in the previous reliability determination process S110 that the current integrated SOC value is low reliability, and this time in the reliability determination process S110 again, it is determined that the current integrated SOC value is low reliability, the previous reliability determination process The time between S110 and the current reliability determination process S110 is measured, and the longer the measurement time is, the more the current integrated SOC value is determined to be lower reliability. This is because the measurement errors of the current measurement are accumulated and the error of the current integrated SOC value is considered to be increased compared to the previous time. Alternatively, the CPU 35 stores the current integrated SOC value in the memory 36 when the current integrated SOC value is determined to be low reliability in the past reliability determination process S110, and again in the reliability determination process S110. The current integrated SOC value is compared with the current integrated SOC value when it is determined that the current integrated SOC value is low. The larger the difference between the two current integrated SOC values, the more the current integrated SOC value is determined to be less reliable. May be.

  In the above embodiment, when the current integrated SOC value is in the second steep change region EH2 and the voltage measurement SOC value is in the second minute change region EL2 (S24: YES), the CPU 35 determines the current integrated SOC value as low reliability. (S110). However, the present invention is not limited to this, and the CPU 35 may be configured to calculate the difference between the current integrated SOC value and the voltage measurement SOC value and determine that the current integrated SOC value is less reliable as the difference is larger. .

  In the above embodiment, when the CPU 35 determines that the current integrated SOC value is in the second steep change region EH2, the CPU 35 executes the SOC initial value determination process A, and the current integrated SOC value is not in the second steep change region EH2. Is determined, the SOC initial value determination process B is executed. However, the present invention is not limited to this, and the CPU 35 may be configured to execute only the SOC initial value determination process A.

  In the above embodiment, when the current integrated SOC value is determined to be low reliability, the battery pack is charged and the full charge is determined by measuring the open-circuit voltage value, and the current integrated SOC value is reset to 100%. did. However, this is not the only case. In addition to the method based on open-circuit voltage measurement, full charge can be reset by detecting that the charging current has dropped during constant voltage charging and has fallen below the specified value. And the current integrated SOC value may be reset to 100%.

  In the above embodiment, when the CPU 35 determines that the current integrated SOC value is low reliability, the CPU 35 resets the current integrated SOC value by, for example, full charging, and then executes the current measurement correction process. It was. However, the present invention is not limited to this, and the CPU 35 may be configured not to perform the current measurement correction process.

  1: battery pack 2: assembled battery 3: BMS 31: control unit 33: current sensor 34: voltage sensor 36: memory

Claims (10)

In the change characteristics of the open circuit voltage with respect to the charge state of the storage element, a high change region in which the open circuit voltage change rate that is the change amount of the open voltage per unit change amount of the charge state is relatively high, and the open circuit voltage change rate is A voltage detection unit for detecting a voltage of a storage element in which a plurality of charged state regions including a relatively low low change region exist;
A control unit,
The controller is
Charging that has a correlation with the state of charge and that is different from the open-circuit voltage and that has a variable element value of the power storage element and estimates the charge state of the power storage element based on the acquired value of the variable element State estimation processing;
Based on the detection result of the voltage detector, an open-circuit voltage measurement process for measuring the open-circuit voltage of the storage element,
The estimation region, to which the estimated value of the charging state based on the value of the variable element belongs, and the measurement region to which the measured value of the charging state corresponding to the measurement value of the open circuit voltage belong to the high change region. Region determination processing for determining whether or not they match,
When it is determined that the estimated region and the measurement region match in the high change region, reliability determination processing that determines that the reliability of the estimated value of the state of charge is higher than when determined not to match, The charge state reliability determination apparatus which has the structure which performs. The state-of-charge reliability determination apparatus according to claim 1,
The controller is
If it is determined in the area determination process that the estimated area and the measurement area do not match,
In the reliability determination process, a state-of-charge reliability determination apparatus that determines that the reliability of the estimated value of the state of charge is lower as the estimated region is farther from the measurement region. The state-of-charge reliability determination device according to claim 1 or 2,
The controller is
On the condition that the estimation area and the measurement area do not coincide with each other in the high change area in the area determination process, the estimated value of the charging state based on the value of the variable element is used as the open circuit voltage in the change characteristic. The charge state reliability determination apparatus which has the structure which performs the change process which changes to the measured value of the charge state corresponding to the measured value of. The state-of-charge reliability determination apparatus according to claim 3,
The controller is
In the area determination process, when it is determined that the estimated area and the measurement area do not match in the high change area,
In the change process, the state of charge reliability determination device has a configuration in which when the power storage element is in a fully charged state, the estimated value of the charged state is changed to a measured value of a charged state corresponding to the measured value of the open circuit voltage. The state-of-charge reliability determination apparatus according to claim 3,
The controller is
In the area determination process, it is further determined whether the estimated area is the high change area and the measurement area is the low change area,
In the reliability determination process, when it is determined that the estimation area is the high change area and the measurement area is the low change area, the time difference from the previous execution of the change process is larger. A state-of-charge reliability determination apparatus that determines that the estimated value of the state of charge is low in reliability. The state-of-charge reliability determination device according to claim 5,
A current detection unit for detecting a charge / discharge current flowing in the power storage element;
The controller is
In the charging state estimation process, the current value detected by the current detection unit is integrated, and as the value of the variable element, the charging state of the power storage element is estimated based on the integrated value,
In the reliability determination process, when it is determined that the estimation area is the high change area and the measurement area is the low change area, a time difference from the previous execution of the change process, and A state-of-charge reliability determination apparatus that determines that the reliability of the estimated value of the state of charge is lower as at least one change amount of the integrated value from the previous execution time of the change process is larger. The state-of-charge reliability determination device according to claim 6,
The controller is
In the region determination process, the estimated value of the charging state based on the integrated value of the current value is any one of the plurality of high change regions or the plurality of low change regions, and the measured value of the open circuit voltage When the measured value of the state of charge corresponding to is a value in a region different from the estimated value of the state of charge, the magnitude relationship between the estimated value of the state of charge and the measured value of the state of charge is the same several times. Judge whether it was continuous,
When it is determined that the change process is performed and the magnitude relationship is the same for a plurality of times, the estimated state of charge based on the integrated value of the current value corresponds to the measured value of the open circuit voltage A state-of-charge reliability determination apparatus having a configuration for executing a correction process for correcting the current value in a direction approaching a measured value of a state of charge to be performed. The state-of-charge reliability determination apparatus according to any one of claims 1 to 7,
The controller is
In the area determination process, it is further determined whether the estimated area is the low change area and the measurement area is the high change area,
In the reliability determination process, when it is determined that the estimation region is the low change region and the measurement region is the high change region, an estimated value of the charging state based on the value of the variable element, and The state-of-charge reliability determination apparatus that determines that the reliability of the estimated value of the state of charge is lower as the difference from the value of the state of charge corresponding to the measured value of the open circuit voltage is larger. A storage element;
A power storage device comprising: the state-of-charge reliability determination device according to any one of claims 1 to 8. In the change characteristics of the open circuit voltage with respect to the charge state of the storage element, a high change region in which the open circuit voltage change rate that is the change amount of the open voltage per unit change amount of the charge state is relatively high, and the open circuit voltage change rate is A method for determining a state of charge reliability of a power storage device including a plurality of regions of a state of charge including a relatively low low change region,
Charging that has a correlation with the state of charge and that is different from the open-circuit voltage and that has a variable element value of the power storage element and estimates the charge state of the power storage element based on the acquired value of the variable element A state estimation process;
An open-circuit voltage measuring step for measuring an open-circuit voltage of the storage element;
The estimation region, to which the estimated value of the charging state based on the value of the variable element belongs, and the measurement region to which the measured value of the charging state corresponding to the measurement value of the open circuit voltage belong to the high change region. An area determination step for determining whether or not they match,
When it is determined that the estimated region and the measurement region match in the high change region, a reliability determination step that determines that the reliability of the estimated value of the state of charge is higher than when determined not to match, A method for determining a state of charge reliability, including:

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