JP5619744B2 - Method and apparatus for detecting state of power storage device - Google Patents

Description

  The present invention relates to a storage device state detection method and apparatus, and more particularly to a storage device state detection method and apparatus for detecting a remaining capacity of a storage device with high accuracy.

  In recent years, needs for power storage devices are increasing. For example, in automobiles, many electric devices that operate by receiving power supply from a storage battery, which is a power storage device, are mounted, and the importance of storage batteries is increasing. In recent years, by-wire has progressed, and safety-related parts represented by electric brakes (EPB) have been electrically controlled. In addition, along with energy saving and carbon dioxide emission regulations, it is required to secure an idling stop function and a restart capability at a short stop at an intersection or the like.

  In fields other than automobiles, for example, in order to promote the use of natural energy such as solar power generation and wind power generation, power storage devices are used for leveling generated power and storing surplus power. Furthermore, the power storage device is also used as a backup power source such as a stabilized power source and an auxiliary power source for supplying power to an electric device during a power failure. As such an electricity storage device, a device that accompanies the movement of ions in an electrolyte such as a secondary battery or a capacitor or in a solid electrolyte is used.

  Originally, the relationship between the remaining capacity of a power storage device and the voltage was defined by the Nernst equation, and the performance of the power storage device could be determined by measuring the voltage. For example, Patent Document 1 discloses that an open circuit voltage (OCV) and a remaining capacity (SOC: State of charge) when a liquid lead-acid battery is sufficiently stabilized after stopping charging and discharging are shown in FIG. It is described that there is a relationship corresponding to 1: 1 as shown, and a technique for detecting the state of the storage battery using such a relationship between OCV and SOC at the time of stability is described.

JP 2007-178215 A

  However, depending on the type of power storage device, there is a case where the OCV at the time of stability hardly changes even though the SOC changes. As an example, FIG. 5 shows the relationship between SOC and stable OCV in an iron phosphate Li-ion battery. In the figure, when the SOC is in the range of SOC_1 to SOC_2 [%], the change in the OCV when stable is very small. Here, SOC_1 and SOC_2 are, for example, about 25% and 75%, respectively, and greatly change to about 50%. Therefore, when the SOC is in the range of SOC_1 to SOC_2, there is a problem that it is difficult to obtain the SOC with sufficient accuracy even if the SOC is obtained by measuring the OCV at the time of stability.

  Further, even when the conversion capacity (SOH) for a new fully charged iron phosphate Li-ion battery is reduced from SOHa to SOHb due to deterioration, for example, as shown in FIG. 6, there is a relationship between each SOC and the stable OCV. , As indicated by reference signs A and B, respectively, are maintained with relatively little change. That is, the SOC region a (for example, 25% to 75%) in which the change in stable OCV before deterioration is small is maintained in the SOC region b (for example, 25% to 75%) of the relatively same size after deterioration. Is done. Therefore, even if it is attempted to obtain SOH based on the relationship between OCV and SOC at the time of stability, it is extremely difficult to obtain this with high accuracy.

  Therefore, the present invention has been made to solve these problems, and there is a region showing a characteristic in which the change in OCV is small with respect to the change in the remaining capacity, which is determined by the reactant used in the power storage device. An object of the present invention is to provide a storage device state detection method and apparatus capable of estimating a remaining capacity of a storage device or a decrease in capacity from a new capacity, and performing state detection with high accuracy even for the storage device. .

  According to a first aspect of the state detection method for an electricity storage device of the present invention, the remaining capacity (SOC) and the converted capacity (SOH) for a new full charge are calculated during operation of a system equipped with the electricity storage device. A state detection method for a power storage device that performs state detection, wherein the operation state of the system is in a state detection mode, and charge control or discharge control of a predetermined capacity is performed on the power storage device (hereinafter simply referred to as charge / discharge control), The open-circuit voltage (OCV) of the power storage device is measured at a predetermined cycle until a predetermined reference time has elapsed after the charge / discharge control is stopped, and is determined based on a function OCV (t) of the time variation of the OCV. And the current SOC of the electricity storage device is calculated using the voltage change amount and the OCV when the reference time has elapsed (hereinafter referred to as a reference OCV). When the system is in an operating state and is not in the state detection mode, the current of the power storage device measured at a predetermined cycle is integrated to calculate a current integrated value, the current integrated value is converted into an SOC change amount, and the SOC The amount of change is added to the current SOC that was calculated last in the state detection mode to calculate the SOC that is being charged / discharged. When the power storage device is in the stopped state, the full charge mode is set and the power storage device is fully charged. Full charge control is performed until charging is performed, and the OCV is measured at a predetermined period until the reference time elapses after the full charge control is stopped, and based on the OCV (t) function of time variation of the OCV. The voltage change amount is calculated, and the converted capacity for the current new full charge of the power storage device using the voltage change amount and the reference OCV when the reference time has elapsed since the full charge control stop. And calculates the SOH).

  According to another aspect of the state detection method of the electricity storage device of the present invention, in the state detection mode, when the reference OCV is larger than the first determination value and not more than the second determination value, the reference OCV and the voltage change amount are The SOC is calculated using a first function created in advance with a variable as the variable. When the reference OCV is equal to or less than the first determination value or greater than the second determination value, the reference OCV is set as a variable. The SOC is calculated using another function created in advance.

  According to another aspect of the method for detecting a state of an electricity storage device of the present invention, in the full charge mode, the SOH is calculated using a second function created in advance with the reference OCV and the voltage change amount as variables. It is characterized by doing.

  In another aspect of the state detection method for an electricity storage device of the present invention, the voltage change amount is obtained from the measurement result of the OCV until the reference time elapses after the charge / discharge control is stopped or the full charge control is stopped. It is calculated as an integral value for a predetermined period based on a function OCV (t) of a predetermined time.

  In another aspect of the state detection method for an electricity storage device of the present invention, the voltage change amount is obtained from the measurement result of the OCV until the reference time elapses after the charge / discharge control is stopped or the full charge control is stopped. The integral value is calculated for each of two or more different periods based on the function OCV (t) of the time.

  Another aspect of the method for detecting a state of an electricity storage device according to the present invention is characterized in that the voltage change amount is calculated by further subtracting a value obtained by multiplying the reference OCV by a time length of the predetermined period.

  Another aspect of the method for detecting a state of an electricity storage device according to the present invention is characterized in that the current integrated value is divided by the SOH calculated last in the full charge mode and converted into the SOC change amount.

  The first aspect of the power storage device state detection device according to the present invention performs the state detection by calculating the remaining capacity (SOC) when executing the state detection mode which is one of the operation methods of the power storage device mounting system. A storage device state detection device for detecting a state by calculating a conversion capacity (SOH) for a new full charge when executing a full charge mode, which is another operation method, comprising a storage unit and the storage device mounted When the system is in operation and in the state detection mode, a predetermined capacity charge control or discharge control (hereinafter simply referred to as charge / discharge control) is performed on the power storage device, and the charge / discharge control is stopped before Until the reference time elapses, the open circuit voltage (OCV) of the electricity storage device is measured at a predetermined cycle, stored in the storage unit, and a predetermined voltage change amount is calculated based on the OCV. The current SOC of the electricity storage device is calculated using the voltage change amount and the OCV when the reference time has elapsed (hereinafter referred to as the reference OCV), and is stored in the storage unit. And during charging / discharging, the current of the electricity storage device measured at a predetermined cycle is integrated to calculate a current integrated value, and the current integrated value is converted into an SOC change amount, and finally in the state detection mode. The calculated current SOC is read from the storage unit and added to the SOC change amount to calculate the SOC that is being charged / discharged. When the storage device mounted system is in the full charge mode in the operating state, the storage device In contrast, full charge control is performed until the battery is fully charged, and the OCV is measured at a predetermined cycle and stored in the storage unit until the reference time elapses after the full charge control is stopped. The voltage change amount is calculated based on the OCV, and the current SOH of the power storage device is calculated using the voltage change amount and the reference OCV when the reference time has elapsed since the full charge control stop. It is characterized by comprising: a state detection unit stored in a storage unit; and a state output means for inputting a determination result from the state detection unit and outputting the result to the outside.

  According to the present invention, even if the power storage device has a region that exhibits a characteristic in which the change in OCV is small with respect to the change in the remaining capacity determined by the reactant used in the power storage device, It is possible to provide a storage device state detection method and apparatus capable of estimating a capacity drop from a new capacity and performing state detection with high accuracy.

It is a flowchart for demonstrating the flow of a process of the state detection method of the electrical storage device of 1st Embodiment of this invention. It is a block diagram which shows the structure of the state detection apparatus of the electrical storage device of 1st Embodiment. It is the graph which compared the voltage change amount and the change with respect to SOC of OCV at the time of stability. It is a graph which shows the relationship between SOC of a liquid type lead acid battery, and stable OCV. It is a graph which shows the relationship between SOC of an iron phosphate type | system | group Li ion battery, and stable OCV. It is a graph which shows the relationship between SOC of an iron phosphate type | system | group Li ion battery when deterioration progresses, and OCV at the time of stability.

  A power storage device state detection method and apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description. Below, the state detection method and state detection apparatus of the electrical storage device of this invention are demonstrated by making an iron phosphate type Li ion battery into an example as an electrical storage device. However, the content described below is not limited to the iron phosphate-based Li ion battery, and can be applied to other power storage devices in the same manner.

  In the present invention, since it is difficult to accurately obtain the SOC from the stable OCV because the change in the stable OCV is small with respect to the change in the SOC, it can be calculated after the end of charge / discharge instead of using the stable OCV. Provided is a storage device state detection method capable of calculating SOC with high accuracy by using a predetermined voltage change amount. As the voltage change amount, a state amount that has a relatively large change with respect to the SOC is used at least in the SOC range in which the change in the stable OCV is small.

  In addition, in the electricity storage device having the above characteristics, even if SOH decreases due to deterioration, the relationship between the SOC and the stable OCV hardly changes. That is, it is extremely difficult to obtain SOH with high accuracy. Therefore, in the method for detecting the state of the electricity storage device of the present invention, SOH can be calculated with high accuracy using the above-described voltage change amount. That is, a relationship between the amount of voltage change measured after full charge and SOH is created in advance and stored in a predetermined storage unit as reference data. Using the current voltage change amount after full charge as an index, the corresponding SOH is selected from the reference data to obtain the current SOH. The reference data format may be saved in a free format such as a function or a data map.

  A power storage device state detection method and apparatus according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a flowchart for explaining the flow of processing in the method for detecting the state of an electricity storage device of this embodiment, and FIG. 2 is a block diagram showing the configuration of the state detection device for the electricity storage device of this embodiment.

  A state detection device 100 according to the present embodiment illustrated in FIG. 2A detects the state of an electricity storage device (storage battery) 10 mounted in the target system 1. The target system 1 includes a charging unit 11 for charging the storage battery 10 and a control unit 12 for controlling charging by the charging unit 11. Moreover, the load 20 mounted in the target system 1 is connected to the storage battery 10, and power is supplied from the storage battery 10 to the load 20. A voltage measuring unit 30 and a current measuring unit 31 are connected to the storage battery 10, and the state detection device 100 inputs each measured value and performs state detection. Furthermore, the temperature measuring means 32 may be connected to the storage battery 10 as necessary, and a temperature measurement value of the storage battery 10 may be input and used for state detection.

  The state detection device 100 includes a state detection unit 110, a storage unit 120, and a state output unit 130. The state detection unit 110 receives the voltage measurement value and the current measurement value of the storage battery 10 from the voltage measurement unit 30 and the current measurement unit 31, respectively, and performs the process according to the state detection method of the present embodiment to detect the state of the storage battery 10. . Further, the temperature measuring means 32 may be connected to the storage battery 10 and a temperature measurement value may be input from this to be used for detecting the state of the storage battery 10. The storage unit 120 stores various reference data and measurement data necessary for the state detection process. Furthermore, the status output means 130 is means for notifying the user or the like of the status detection result or the like.

  In addition, the state detection apparatus 100 may take the form incorporated in the control apparatus 12 of the target system 1. Alternatively, as illustrated in FIG. 2B, the state detection device 100 may be provided outside the target system 1 and the measurement data recording device 40 that records measurement data may be provided inside the target system 1. Regardless of wired or wireless data, the data recorded in the measurement data recording device 40 is transmitted to the state detection device 100 installed outside the target system 1 by using remote communication or using a portable storage medium. The state may be input and the state may be determined to detect the state.

  In the storage device state detection method of the present embodiment, when the target system 1 is in the operating state and the storage battery 10 is charging / discharging, the target system 1 is in the operating state and the storage battery 10 executes the state detection mode. And when the target system 1 is in the operating state and executing the full charge mode. Hereinafter, the time when the target system 1 is charging / discharging or in the state detection mode is referred to as a normal operation mode, and the time when the target system 1 is fully charged the storage battery 10 is referred to as a full charge mode. Moreover, in the state detection method of the electrical storage device of this embodiment, when the target system 1 is in an operation state and charging / discharging of the storage battery 10 is stopped, the OCV of the storage battery 10 is measured to perform highly accurate state detection. Therefore, the state detection at this time is called a state detection mode. In the operation method of the storage device mounted system, select the state detection mode or full charge mode under the condition that the operation is stopped and the maintenance or stop is performed for the normal operation mode in which the storage device is operating. May be implemented.

  The storage battery 10 is an iron phosphate Li-ion battery in which the relationship between the SOC and the OCV at the time of stability changes as shown in FIG. In the following, first, a method for measuring the OCV of the storage battery 10 and performing state detection with high accuracy in the state detection mode in which the storage battery 10 has stopped charging and discharging will be described.

  The storage battery 10 having the SOC vs. stable OCV relationship shown in FIG. 5 is stable when the stable OCV is less than OCV_1 (eg, 3.28V) or greater than OCV_2 (eg, 3.31V). Therefore, the SOC can be accurately obtained from the stable OCV using the relationship between the SOC and the stable OCV. On the other hand, when the OCV at the time of stability is OCV_1 or more and OCV_2 or less, the SOC changes in a wide range from SOC_1 to SOC_2, whereas the OCV at the time of change changes only slightly. Therefore, in the present embodiment, the SOC can be calculated with high accuracy by using a predetermined voltage change amount having a larger change instead of the stable OCV.

（２）充放電停止からの経過時間がｔ１からｔ２の間のＯＣＶ_now（ｔ）と所定の基準ＯＣＶ（ＯＣＶ_baseとする）との差の積算値（ＤＳt1_t2とする）

The predetermined voltage change amount is calculated from a state amount when the internal state of the storage battery 10 after the charge / discharge stop is in the middle of relaxation. Specifically, using the OCV measurement value (hereinafter referred to as OCV_now (t)) of the storage battery 10 when the elapsed time from the stop of charging / discharging is t, one of the voltage integrated values calculated below is a voltage. It can be used for the amount of change.
(1) The integrated value of OCV_now (t) during the elapsed time from the charge / discharge stop between t1 and t2 (referred to as St1_t2)

(2) The integrated value (DSt1_t2) of the difference between OCV_now (t) and the predetermined reference OCV (referred to as OCV_base) between the time t1 and t2 after the charge / discharge stop

  In the formula (2), OCV_base that is the reference OCV is a stable OCV when the internal state of the storage battery 10 after charging and discharging stops. In Expression (2), OCV_base × Δt is subtracted from the integrated value of OCV_now. However, an effect is obtained that the number of operations can be reduced as compared with integrating the subtracted OCV_base every OCV_now (t). In the iron phosphate Li-ion battery, the time from the stop of charging / discharging until the internal state becomes stable is extremely shorter than that of the liquid lead acid battery, and the OCV can be obtained in a stable period of 30 minutes or more, for example, about 1 hour. Also, Δt = t2−t1.

  Since the OCV measurement time and Δt described above vary depending on the type of battery, it is necessary to acquire reference data. These OCV measurement time and Δt are the amount of active material used, the particle size, the amount of electrolyte, the thickness of the electrode plate, even in the electricity storage device conforming to the same standard using the same reactant. The reference data needs to be acquired in each case. These OCV measurement times and Δt may be used within a range in which the design of the electricity storage device is not changed, as long as the reference data is generated once, if the electricity storage device is the same design with the same reactant. . These OCV measurement times and Δt can be used by similarly creating reference data even when used in a format such as an assembled battery or a battery pack.

  FIG. 3 shows a comparison of the DSt1_t2 calculated with the formula (2) with respect to the SOC in comparison with the stable OCV. In the figure, a change in DSt1_t2 is indicated by a symbol C, and a change in OCV when stable is indicated by a symbol D. As shown in the figure, the change in OCV is relatively small between SOC_1 and SOC_2, whereas DSt1_t2 changes greatly between SOC_1 and SOC_2.

または

Assuming that the state detection unit 110 performs n-th state detection in the state detection mode after charging / discharging of the storage battery 10, the OCV_base_n that is the stable OCV at this time and the voltage change amount St1_t2_n or DSt1_t2_n described above are used. The SOC_n of the storage battery 10 can be obtained as follows.

Or

  The functions F1 (OCV_base_n), G1 (OCV_base_n, St1_t2_n), G2 (OCV_base_n, DSt1_t2_n), and F2 (OCV_base_n) used in the above formulas (3) to (5) are determined in advance based on the characteristics of the storage battery 10. And stored in, for example, the ROM portion of the storage unit 120. The functions F1 (OCV_base_n) and F2 (OCV_base_n) for calculating the SOC_n from the OCV_base_n are functions indicating the relationship between the SOC and the stable OCV as in the conventional case, and can be expressed in one function form. In the present embodiment, between OCV1 and OCV2 where the change in OCV_base_n is small, the function G1 (OCV_base_n, St1_t2_n) or G2 (OCV_base_n, DSt1_t2_n) is calculated based on the voltage change St1_t2_n or DSt1_t2_n.

In the above, the voltage change amounts St1_t2_n and DSt1_t2_n are defined as an integrated value of OCV_now (t) and an integrated value of (OCV_now (t) −OCV_base_n) in one time range from t1 to t2 (hereinafter referred to as an integrated time range). However, the integrated value may be calculated and used in two or more integrated time regions. As an example, in addition to the integration time range of t1 to t2, the voltage change amounts St3_t4_n and DSt3_t4_n are calculated in the integration time range of t3 to t4, which is different from the integration time range of t1 to t2, and equations (4-1) and (4-2) ) Can be changed to the following equation, so that SOC1_n can be calculated with higher accuracy.

  Furthermore, it is also possible to calculate the equations (3) to (5) after correcting the temperature using the temperature measurement value of the storage battery 10. For example, since the OCV of the storage battery 10 is considered to be affected by temperature, correction is performed by substituting a temperature measurement value into a predetermined temperature function so that OCV_base_n becomes a stable OCV at the reference temperature, and this temperature-corrected OCV_base_n It is possible to calculate SOC_n using.

  Next, a state detection method when the target system 1 is in an operating state and the storage battery 10 is being charged / discharged and the state detection mode cannot be performed will be described below. When the storage battery 10 is being charged / discharged, the current measurement value I_now (t) of the storage battery 10 is acquired at a predetermined period, and the integrated value is calculated, and this is used as the amount of change in SOC (hereinafter referred to as ΔSOCon). ) Is calculated. Then, the current SOC during charging / discharging is calculated by adding the SOC change amount ΔSOCon to SOC_n−1 obtained in the previous state detection mode. Since the SOC is given as a percentage (%) with respect to the full charge capacity at that time, the integrated value of the current measurement value I_now (t) is used as the SOC change amount ΔSOCon using the conversion capacity (SOH) with respect to the new capacity at that time. Need to convert. In this embodiment, the full charge capacity of the storage battery 10 is updated to the latest value in the full charge mode.

  Next, in the full charge mode, a method for calculating the full charge capacity, that is, SOH that has been reduced due to deterioration of the storage battery 10 will be described below. The full charge mode is an SOC region in which the relationship between the OCV and the SOC is flat for the purpose of managing the state of the storage battery 10 in order to reset the state amount, recover the state, equalize the state amount between cells, and the like. Charging is performed so that the SOC becomes higher than that. For example, the full charge condition for fully charging an iron phosphate-based Li ion battery is to perform CC (constant current) charge up to 3.6 V at 0.3 to 1.0 CA current in terms of C rate. After reaching 6V, charging control is performed until CV (constant voltage) charging reaches 0.05 CA. However, this is an example of charge control for performing full charge, and is not limited to this full charge condition. The C rate corresponds to a discharge current that discharges the entire capacity in one hour.

または

In the present embodiment, when the m-th full charge mode is started from the start of use of the storage battery 10 or the like, the storage battery 10 is first controlled to be fully charged according to the full charge condition as described above. Then, after completion of the full charge control, a predetermined period OCV_now (t) is measured, and based on this, the voltage change amount St1_t2_n or DSt1_t2_n is calculated by the formula (1) or the formula (2). Using this voltage change amount St1_t2_n or DSt1_t2_n, the full charge capacity (SOH_m) is calculated from the following equation.

Or

  SOH_m calculated by the above formulas (6-1) and (6-2) is, for example, a capacity expressed in “mAh” units. In the above description, the voltage change amount St1_t2_n or DSt1_t2_n calculated in one integration time region from t1 to t2 is used. However, the integration value may be calculated and used in two or more integration time regions. In this case, the function H1 of the equation (6-1) and the function H2 of the equation (6-2) are functions of integral values in two or more integration time ranges, respectively.

  When SOH_m is calculated in the full charge mode, it is stored in the storage unit 120 and used for calculating the SOC during charging and discharging of the storage battery 10 thereafter. That is, when converting the integrated value of the current measurement value I_now (t) to the SOC change amount ΔSOC during charging / discharging of the storage battery 10, the latest SOH_m updated in the last full charge mode is read from the storage unit 120 and used. .

  Below, the flow of the process in the state detection method of the electrical storage device of this embodiment is demonstrated using FIG. The state detection unit 110 provided in the state detection device 100 according to the present embodiment starts detection of the state of the storage battery 10 according to a predetermined timing or a request signal from inside or outside the state detection device 100. As the predetermined timing, for example, a periodic timing for every predetermined time interval can be used. In addition, as a request signal from the inside of the state detection device 100, there is a request signal that is added based on the previous state detection result. On the other hand, as a request signal from the outside of the state detection device 100, a request signal from a user or maintenance staff of the target system 1, a request signal from a device in the target system 1 connected to the storage battery 10, and the target A request signal from an external system connected to the system 1 can be considered.

  As processing in the state detection unit 110, in step S1, it is determined whether or not the full charge mode is requested. The full charge mode may be requested from the outside of the state detection device 100 or may be requested from the inside. When periodic maintenance of the storage battery 10 is performed as a request from the outside, a forced execution command by a user or maintenance staff, a request signal from a device in the target system 1 connected to the storage battery 10, and the target system 1 There is a request signal from an external system connected to. In addition, as a request from the inside of the state detection device 100, it may be determined that the SOC has decreased as a result of the state detection so far. If it is determined in step S1 that there is any of the above-described full charge mode requests, the process proceeds to step S4 for determining the full charge mode start condition.

  On the other hand, if it is determined in step S1 that the full charge mode is not requested, the process proceeds to step S2 as the normal operation mode, where it is determined whether or not the state detection mode is requested. Regarding the state detection mode, there are requests from the outside of the state detection device 100 and requests from the inside of the state detection device 100. When periodic maintenance of the storage battery 10 is performed as a state detection mode request from the outside of the state detection apparatus 100, a forced execution command by a user or a maintenance staff, a device in the target system 1 connected to the storage battery 10, or the like And a request signal from an external system connected to the target system 1. In addition, as a state detection mode request from the inside of the state detection device 100, there are cases where it is determined that a predetermined request condition is satisfied as a result of state detection so far.

  As a result of the determination in step S2, if the state detection mode is requested, the process proceeds to step S3. If the state detection mode is not requested, the process proceeds to step S10. In step S3, it is determined whether or not the state detection mode is permitted. The state detection mode is permitted when (1) the execution of the state detection mode is permitted in advance by a permission signal from the user or an external system, or (2) the state detection mode is forcibly executed from the outside. In this case, the process proceeds to the state detection mode process in step S20. On the other hand, if it is determined that the state detection mode is not permitted, the process proceeds to step S10.

When it is determined in step S2 that the state detection mode is not requested, or when it is determined in step S3 that the state detection mode is not permitted, the calculation of the SOC based on the current integrated value is performed in steps S10 to S13. Do. That is, in step S10, current measurement values I_now (t) are sequentially integrated in a predetermined integration time range to calculate a current integration value (Isum), and using SOH_m read from the storage unit 120 in step S11, the following equation is obtained. Thus, it is converted into the SOC change amount ΔSOCon.
ΔSOCon = Isum / SOH_m

In the next step S12, the SOCn-1 calculated in the previous state detection mode is read from the storage unit 120, and in step S13, the current SOC is calculated from the SOCn-1 and ΔSOCon by the following equation.
SOC = SOCn-1 + ΔSOCon

  If it is determined in step S3 that the state detection mode is permitted, processing in the state detection mode is performed in steps S20 to S23. Here, it is assumed that the state detection mode is performed n times after the use of the storage battery 10 is started. In step S20, charge control or discharge control is performed on the storage battery 10 as charge / discharge control before state detection. This makes it possible to perform state detection under stable conditions by making the state of the electrolyte solution of the storage battery 10 when performing the state detection mode as reproducible as possible. The amount of charge or the amount of discharge performed as the charge / discharge control before state detection is suitably determined according to the type, model number, capacity, combined quantity, etc. of the storage battery 10. As an example, in the case of a 18650-type iron phosphate Li-ion battery, it is desirable to perform charging at 2% or more in terms of new capacity.

  In step S21, measurement of OCV_now (t) is started after the end of charge / discharge control before state detection, and this is continued until the reference time at which the reference OCV (OCV_base_n) is obtained. The reference time for obtaining OCV_base_n is preferably a time that has passed 30 minutes or more from the end of the charge / discharge control before state detection. For example, in an iron phosphate Li-ion battery, it is preferably about 1 hour. The reference time varies depending on the size and type of the battery.

The state detection mode can be detected not only when the current of the storage battery 10 is 0, but also when the following current / voltage is measured.
(1) A small current (dark current) is consumed by a measuring instrument, controller, communication device, etc., but the influence on the voltage change amount can be corrected and is in an allowable range that can be regarded as a pseudo-OCV.
(2) Although the current exceeding the allowable range is consumed, the reference data is created based on the voltage change amount measured in advance under the same conditions, and the reference data selected based on the current value. When the measured voltage can be handled as OCV by using
When any of the above conditions is satisfied, the voltage measurement value can be handled as OCV.

  In step S22, the voltage change amount St1_t2_n or DSt1_t2_n is calculated from the equation (1) or equation (2) based on the measured OCV_now (t). Note that the voltage change amount may be calculated and used not only in one integrated time region t1 to t2 but also in two or more integrated time regions.

  In step S23, among the functions F1 (OCV_base_n), G1 (OCV_base_n, St1_t2_n), G2 (OCV_base_n, DSt1_t2_n), and F2 (OCV_base_n) shown in equations (3) to (5), OCV_base_n is represented by equations (3) to (3). Any function satisfying the condition shown in 5) is read from the storage unit 120, and the current remaining capacity SOC_n is calculated from the OCV_base_n and the voltage variation St1_t2_n or DSt1_t2_n using this function.

  Next, the flow of processing in the full charge mode will be described below. If it is determined in step S1 that there is a full charge mode request, it is determined in step S4 whether a full charge mode start condition is satisfied. As the full charge mode start condition, there are conditions such as permission from the user or the like, permission signal from the outside of the state detection device, forced state detection execution command, and the like. When any of these conditions is satisfied, the full charge mode processing of steps S30 to S33 is performed, and when any of the conditions is not satisfied, the processing is terminated without processing.

  In step S30, the storage battery 10 is controlled to be fully charged according to the aforementioned full charge condition. When the full charge control is completed, the measurement of OCV_now (t) is started in step S31, and this is continued until the reference time at which the reference OCV (OCV_base_n) is obtained. In step S32, the voltage change amount St1_t2_n or DSt1_t2_n is calculated from the measured OCV_now (t) using the formula (1) or the formula (2). Note that the voltage change amount may be calculated and used not only in one integrated time region t1 to t2 but also in two or more integrated time regions.

  In step S33, the function H1 (OCV_base_n, St1_t2_n) shown in Expression (6-1) or the function H2 (OCV_base_n, DSt1_t2_n) shown in Expression (6-2) is read from the storage unit 120, and this is read. By using OCV_base_n and the voltage change amount St1_t2_n or DSt1_t2_n, the remaining capacity at full charge, that is, SOH_m is calculated. Since SOH_m is calculated as an absolute amount expressed in units of “mAh”, for example, a reduction amount from the initial capacity when the use of the storage battery 10 is started can be calculated.

  When SOH_m is calculated in step S33, it is stored in the storage unit 120 in step S34. This SOH_m is read from the storage unit 120 and used in the process of step S11 for calculating the SOC change amount ΔSOCon from the current integrated value during the subsequent charging and discharging of the storage battery 10.

  In step S5, the processing result in each mode is output to the target system 1 or the user using the state output means 130. When the process of step S13 or step S23 in the normal operation mode is performed, the calculated SOC_n is output to the state output unit 130, and when the process of step S33 is performed, SOH_m is output to the state output unit 130. Is done. In addition, when the calculated SOC_n is compared with a predetermined threshold value and it is determined that the remaining capacity is insufficient, a signal for notifying this is output from the state output unit 130 to the target system 1 or an external system. Can be.

  As described above, according to the present invention, it is possible to estimate the remaining capacity with high accuracy and perform state detection even for an electricity storage device in which it is difficult to accurately estimate the remaining capacity from the stable OCV. It becomes possible to provide the state detection method and apparatus of an electrical storage device. Thereby, the remaining capacity of the electricity storage device can be obtained with high accuracy, and the state detection can be performed, and an unexpected situation where the electricity storage device mounting system stops due to insufficient charging can be avoided.

  Further, in the power storage device state detection method and apparatus of the present invention, the SOC of the power storage device is calculated in the normal operation mode, while the SOH is calculated in the full charge mode. It is possible to notify the user or the like with a clear distinction. In particular, in the full charge mode, since SOH is calculated after full charge control, it is possible to calculate SOH with high accuracy, thereby detecting deterioration of the electricity storage device at an early stage and preventing damage or the like in advance. it can.

  The power storage device state detection method and apparatus according to the present invention include, for example, an electric vehicle, a mobile phone, a backup battery that operates in the event of a power failure, and further, the generation of natural energy by sunlight or wind power in cooperation with the grid power. The present invention can be applied to an apparatus in which an electricity storage device such as an electricity storage device used for electric power leveling and a system incorporating the electricity storage device is mounted and monitoring or state detection is necessary. Suitable for power storage devices that have small changes in stable OCV against changes in remaining capacity, such as iron phosphate-based Li-ion batteries, vanadium phosphate-based Li-ion batteries, and lithium-ion batteries that use titanium oxide. It is.

  Note that the description in the present embodiment shows an example of the state detection method and apparatus of the electricity storage device according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the power storage device state detection method and the apparatus in the present embodiment can be appropriately changed without departing from the spirit of the present invention.

1: Target system 10: Power storage device 11: Charging means 12: Control means 20: Load 30: Voltage measurement means 31: Current measurement means 32: Temperature measurement means 100: State detection device 110: State detection part 120: Storage part 130: Status output means

Claims (8)

A state detection method for a power storage device that detects a remaining capacity (SOC) and a converted capacity (SOH) for a new full charge during operation of a system equipped with the power storage device, and detects the state of the power storage device,
The operation state of the system is in the state detection mode, a predetermined capacity charge control or discharge control (hereinafter simply referred to as charge / discharge control) is performed on the power storage device, and a predetermined reference time is elapsed after the charge / discharge control is stopped. The open circuit voltage (OCV) of the electricity storage device is measured at a predetermined period until it elapses, and a predetermined voltage change amount is calculated based on the OCV (t) function OCV (t), and the voltage change amount and the The current SOC of the electricity storage device is calculated using the OCV when the reference time has elapsed (hereinafter referred to as the reference OCV),
When the system is in operation and not in state detection mode,
The current integrated value measured by a predetermined period is integrated to calculate a current integrated value, the current integrated value is converted into an SOC change amount, and the SOC change amount is calculated last in the state detection mode. Calculate the SOC during charging / discharging by adding to the current SOC,
As a full charge mode when the electricity storage device is in a stopped state,
The full charge control is performed until the power storage device is fully charged, the OCV is measured at a predetermined period from the stop of the full charge control until the reference time elapses, and a function OCV (OCV ( t) to calculate the amount of change in voltage, and using the amount of change in voltage and the reference OCV when the reference time has elapsed since the stop of full charge control, the conversion capacity for the current full charge of the power storage device (SOH) is calculated. The state detection method of the electrical storage device characterized by the above-mentioned. In the state detection mode,
When the reference OCV is greater than the first determination value and less than or equal to the second determination value, the SOC is calculated using a first function created in advance with the reference OCV and the voltage change amount as variables. ,
When the reference OCV is less than or equal to the first determination value or greater than the second determination value, the SOC is calculated using another function created in advance using the reference OCV as a variable. Item 2. A method for detecting a state of an electricity storage device according to Item 1. In the full charge mode,
The method for detecting a state of an electricity storage device according to claim 1 or 2, wherein the SOH is calculated using a second function created in advance with the reference OCV and the voltage change amount as variables. The amount of voltage change is a predetermined period based on a function OCV (t) of time obtained from the measurement result of the OCV until the reference time elapses after the charge / discharge control is stopped or the full charge control is stopped. It is calculated as an integral value. The state detection method of the electrical storage device of any one of Claims 1 thru | or 3 characterized by the above-mentioned. The voltage change amount is two or more different based on a function OCV (t) of time obtained from the measurement result of the OCV until the reference time elapses after the charge / discharge control is stopped or the full charge control is stopped. The state detection method for an electricity storage device according to any one of claims 1 to 3, wherein the value is calculated as an integral value in each of the periods. The method for detecting a state of an electricity storage device according to claim 4, wherein the voltage change amount is calculated by further subtracting a value obtained by multiplying the reference OCV by a time length of the predetermined period.

The method according to claim 1, wherein the current integrated value is divided by the SOH calculated last in the full charge mode and converted into the SOC change amount. The remaining capacity (SOC) is calculated at the time of execution of the state detection mode, which is one of the operation methods of the storage device mounted system, while the full charge mode, which is another of the operation methods, is performed at the time of execution. A state detection device for an electricity storage device that performs state detection by calculating a converted capacity (SOH) for full charge,
A storage unit;
When the storage device mounted system is in an operational state and in the state detection mode, a predetermined capacity charge control or discharge control (hereinafter simply referred to as charge / discharge control) is performed on the storage device, and the charge / discharge control is stopped. Then, an open circuit voltage (OCV) of the power storage device is measured at a predetermined cycle and stored in the storage unit until a predetermined reference time elapses, and a predetermined voltage change amount is calculated based on the OCV, The current SOC of the electricity storage device is calculated using the voltage change amount and the OCV when the reference time has elapsed (hereinafter referred to as the reference OCV), and is stored in the storage unit. And during charging / discharging, the current of the electricity storage device measured at a predetermined cycle is integrated to calculate a current integrated value, and the current integrated value is converted into an SOC change amount, The current SOC that was calculated last in the state detection mode is read from the storage unit and added to the SOC change amount to calculate the SOC that is being charged / discharged. When the full charge control is performed until the power storage device is fully charged, the OCV is measured at a predetermined period until the reference time elapses after the full charge control is stopped, and is stored in the storage unit, The voltage change amount is calculated based on the OCV, and the current SOH of the power storage device is calculated using the voltage change amount and the reference OCV when the reference time has elapsed since the full charge control stop. A state detection unit to be stored in the storage unit;
And a state output unit that inputs a determination result from the state detection unit and outputs the determination result to the outside.

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