Battery management device, battery system, and battery management method

Abstract

Provided are a power storage battery management device, a power storage battery system, and a power storage battery management method, all of which make it possible to estimate the degree of degradation of a storage battery with high accuracy. The power storage battery management device (BMS7) comprises a control unit (71) that: acquires, in a target period, the value of electric current flowing through a power storage battery, the temperature of the power storage battery, and a charging rate of the power storage battery; determines an operation mode of the power storage battery in the target period on the basis of the electric current value and the charging rate; and estimates the degree of degradation of the power storage battery in the target period on the basis of the operation mode and the temperature. The target period is sectioned by the switching of operation states that are of the power storage battery and that include charging, discharging, and retention.

Description

Technical Field

[0001] The present disclosure relates to a battery management device, a battery system, and a battery management method.

Background Art

[0002] Conventionally, in order to manage a battery, a technique for measuring the degree of deterioration (SOH: State of Health), which is an index of the deterioration state of the battery, has been disclosed. For example, a technique is known in which the battery is fully charged and then fully discharged, and the degree of deterioration is measured from the amount of discharge power during that period. However, measuring the degree of deterioration of the battery by full discharge generally requires operating the battery in a dedicated operating state, and the use of the battery is restricted during the measurement of the degree of deterioration of the battery. For example, Patent Document 1 discloses a technique for estimating the degree of deterioration of a battery based on information obtained without operating the battery in a dedicated operating state.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, further improvement is required for the estimation accuracy of the degree of deterioration of the battery.

[0005] In view of such circumstances, an object of the present disclosure is to provide a battery management device, a battery system, and a battery management method capable of accurately estimating the degree of deterioration of a battery.

Means for Solving the Problems

[0006] A battery management device according to an embodiment of the present disclosure is During a target period, an electric current value flowing through the storage battery, the temperature of the storage battery, and the charge rate of the storage battery are acquired, an operation mode of the storage battery during the target period is determined based on the electric current value and the charge rate, and a degree of deterioration of the storage battery during the target period is estimated based on the operation mode and the temperature. The control unit is provided. The target period is divided by switching the operating state of the storage battery including charging, discharging, and holding.

[0007] A storage battery system according to an embodiment of the present disclosure includes a storage battery and a storage battery management device including a control unit. The control unit During a target period, an electric current value flowing through the storage battery, the temperature of the storage battery, and the charge rate of the storage battery are acquired. Based on the electric current value and the charge rate, an operation mode of the storage battery during the target period is determined. Based on the operation mode and the temperature, a degree of deterioration of the storage battery during the target period is estimated. The target period is divided by switching the operating state of the storage battery including charging, discharging, and holding.

[0008] A storage battery management method according to an embodiment of the present disclosure is a storage battery management method executed by a storage battery management device having a control unit, wherein the control unit acquires an electric current value flowing through a storage battery, the temperature of the storage battery, and the charge rate of the storage battery during a target period; determines an operation mode of the storage battery during the target period based on the electric current value and the charge rate; and estimates a degree of deterioration of the storage battery during the target period based on the operation mode and the temperature. The target period is divided by switching the operating state of the storage battery including charging, discharging, and holding.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a battery management device, a battery system, and a battery management method capable of accurately estimating the degree of deterioration of a storage battery.

Brief Description of Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0011] Hereinafter, a battery management device, a battery system, and a battery management method according to an embodiment of the present disclosure will be described with reference to the drawings.

[0012] In each figure, the same or corresponding parts are denoted by the same reference numerals. In the description of the present embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0013] (Configuration of Battery System) FIG. 1 is a schematic configuration diagram showing an example of a battery system 1 according to an embodiment of the present disclosure. The battery system 1 includes a power conditioner 2, a battery 3, a current sensor 4, a temperature sensor 5, a voltage sensor 6, and a battery management device 7. The power conditioner 2 is also referred to as a PCS (Power Conditioning System). The battery management device 7 is also referred to as a BMS (Buttery Management System). In the battery system 1, the battery 3 is connected to the outside of the battery system 1, such as a power grid 8 and a load 9, via the power conditioner 2. Thereby, the battery system 1 can supply the power charged in the battery 3 to the power grid 8, the load 9, and the like. Also, the battery system 1 can charge the battery 3 with the power supplied from the power grid 8 or the like.

[0014] As shown by the broken line in FIG. 1, the power conditioner 2, the battery 3, the current sensor 4, the temperature sensor 5, the voltage sensor 6, and the battery management device 7 are connected to be communicable with each other by wire or wirelessly via a network such as CAN (Controller Area Network). In the present embodiment, as shown in FIG. 1, the battery system 1 includes one each of the power conditioner 2, the battery 3, the current sensor 4, the temperature sensor 5, the voltage sensor 6, and the battery management device 7, but the number of each of these may be any number.

[0015] The power conditioner 2 converts the DC power discharged from the battery 3 to the outside into AC power. Also, the power conditioner 2 converts the AC power supplied from the outside to the battery 3 into DC power.

[0016] The storage battery 3 is a rechargeable battery such as a lithium-ion battery, for example. The storage battery 3 includes a battery module 32 composed of one or more cells 31. The storage battery 3 can store electricity in the cells 31 that make up the battery module 32 and discharge it from the cells 31. In the present embodiment, it will be described that a plurality of cells 31 are connected in series in the battery module 32, but the cells 31 may be connected in parallel. Also, in the storage battery 3, a plurality of battery modules 32 may be connected in series or in parallel.

[0017] The current sensor 4 measures the current value flowing through the storage battery 3. The current value flowing through the storage battery 3 includes at least one of the current value input to the storage battery 3 and the current value output from the storage battery 3. The current sensor 4 transmits the measured current value as the current value flowing through the storage battery 3 to, for example, the battery management device 7 or the like. In the present embodiment, the current sensor 4 is connected in series with one terminal of the battery module 32. However, the current sensor 4 is not limited to one terminal of the battery module 32 and may be connected at any position where the current value flowing through the storage battery 3 can be measured.

[0018] The temperature sensor 5 measures the temperature of the storage battery 3. The temperature sensor 5 transmits the measured temperature as the temperature of the storage battery 3 to, for example, the battery management device 7 or the like. In the present embodiment, the temperature sensor 5 is installed on the outer surface of one terminal of the battery module 32. However, the temperature sensor 5 is not limited to the outer surface of one terminal of the battery module 32 and may be installed at any position where the temperature of the storage battery 3 can be measured.

[0019] The voltage sensor 6 measures the voltage value of the storage battery 3. The voltage sensor 6 transmits the measured voltage value as the voltage value of the storage battery 3 to, for example, the battery management device 7 or the like. The voltage value of the storage battery 3 includes, for example, the voltage values during charging and discharging and the value of the open-circuit voltage in a state where no current is flowing. In the present embodiment, the voltage sensor 6 is connected in parallel with both terminals of the battery module 32. However, the voltage sensor 6 is not limited to both terminals of the battery module 32 and may be installed at any position where the voltage value of the storage battery 3 can be measured.

[0020] The battery management device 7 manages the battery 3. The battery management device 7 controls, for example, the power-on or power-off of the battery 3 or the transmission of information from the battery 3 to the battery management device 7.

[0021] In the battery system 1 according to an embodiment of the present disclosure, the battery management device 7 communicates with a current sensor 4, a temperature sensor 5, a voltage sensor 6, etc., and acquires the current value flowing through the battery 3, the temperature of the battery 3, and the charge rate of the battery 3. The battery management device 7 determines the operation mode of the battery based on the acquired current value, temperature, and charge rate of the battery 3, and estimates the degree of deterioration. In this way, the degree of deterioration of the battery 3 can be estimated based on the information acquired without operating the battery 3 in a dedicated operating state.

[0022] The degree of deterioration of the battery 3 is represented by SOH (State of Health). SOH is the ratio (%) of the current full charge capacity (FCC) to the design capacity (DC). The design capacity may be, for example, the initial value of the full charge capacity of the battery 3 determined by the manufacturer of the battery 3. The charge rate of the battery 3 is represented by SOC (States of Charge). SOC is the ratio (%) of the current charge amount to the current full charge capacity.

[0023] Also, in the present disclosure, in the following description, the operation state of the battery 3 is also referred to as the operation mode. The operation mode of the battery 3 includes, for example, an operation mode in which the battery 3 performs charge and discharge and a holding mode in which the power is held, which is an operation state of holding power.

[0024] (Configuration of Battery Management Device) Referring to FIG. 1, the schematic configuration of the battery management device 7 according to this embodiment will be described. As shown in FIG. 1, the battery management device 7 includes a control unit 71, a communication unit 72, a storage unit 73, an output unit 74, and an input unit 75. The control unit 71, the communication unit 72, the storage unit 73, the output unit 74, and the input unit 75 are connected to each other so as to be communicable, either by wire or wirelessly.

[0025] The control unit 71 includes one or more processors. The processor may be, for example, a general-purpose processor such as a CPU (Central Processing Unit) or a dedicated processor specialized for specific processing. The control unit 71 is not limited to a processor and may include one or more dedicated circuits. The dedicated circuit may be, for example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The control unit 71 controls the communication unit 72, the storage unit 73, the output unit 74, and the input unit 75 described above in order to realize the functions of the battery management device 7. The control characteristic of this embodiment performed by the control unit 71 will be described later in more detail.

[0026] The communication unit 72 includes one or more communication modules. The communication module is, for example, a CAN communication module, a wired LAN (Local Area Network) communication module, or a wireless LAN communication module. In this embodiment, the battery management device 7 can communicate with the power conditioner 2, the battery 3, the current sensor 4, the temperature sensor 5, the voltage sensor 6, etc. included in the battery system 1 via the communication unit 72.

[0027] The storage unit 73 is, for example, a semiconductor memory, a magnetic memory, or an optical memory. The storage unit 73 may be a cache memory of the processor included in the control unit 71. The storage unit 73 may be a volatile storage device or a non-volatile storage device. The storage unit 73 stores a system program, an application program, embedded software, information, etc. for realizing the functions of the battery management device 7.

[0028] The output unit 74 outputs information in the form of images, sounds, etc. The output unit 74 includes output devices such as a display and a speaker, for example.

[0029] The input unit 75 receives input operations. The input unit 75 includes input devices such as a touch panel and a remote controller, for example.

[0030] (Example of Processing of Battery Management Device) With reference to FIGS. 2 and 3, an example of the process (hereinafter also referred to as "this process") for estimating the degree of deterioration of the storage battery 3 executed by the storage battery management device 7 according to the present embodiment will be described. This process corresponds to the storage battery management method according to the present embodiment. FIG. 2 shows a flowchart of an example of this process executed by the storage battery management device 7. FIG. 3 shows a flowchart in which a part of the process shown in FIG. 2 is detailed.

[0031] Referring to FIG. 2, in step S1, the control unit 71 performs initialization necessary for this process.

[0032] Specifically, the control unit 71 acquires the initial value of the state of charge of the storage battery 3 and the initial value of the degree of deterioration, which are stored in the storage unit 73. The initial value of the state of charge and the initial value of the degree of deterioration are the values of the state of charge and the degree of deterioration of the storage battery 3 at the start time of this process, respectively. The initial value of the state of charge and the initial value of the degree of deterioration of the storage battery 3 are, for example, the state of charge and the degree of deterioration of the storage battery 3 calculated by the same process as the previous execution of this process. Here, the control unit 71 may acquire the initial value by a process different from this process. For example, the control unit 71 may use the measured value of the state of charge and the measured value of the degree of deterioration of the storage battery 3 measured by operating the storage battery 3 in a dedicated operating state as the initial value.

[0033] Further, the control unit 71 stores the start date and time of the first day of the target period during which the degree of deterioration of the storage battery 3 in this process is estimated. Specifically, the control unit 71 stores the date and time at the start of this process in the storage unit 73. Hereinafter, the target period during which the degree of deterioration of the storage battery 3 in this process is estimated is also simply referred to as the "target period".

[0034] In step S2, the control unit 71 acquires the current value flowing through the storage battery 3, the temperature of the storage battery 3, and the charge rate of the storage battery 3.

[0035] Specifically, the control unit 71 communicates with the current sensor 4 via the communication unit 72, and receives, as the current value flowing through the storage battery 3, the current value measured by the current sensor 4, for example, at intervals of 1 second. Further, the control unit 71 communicates with the temperature sensor 5 via the communication unit 72, and receives, as the temperature of the storage battery 3, the temperature measured by the temperature sensor 5, for example, at intervals of 1 second. Furthermore, the control unit 71 calculates the charge rate of the storage battery 3 based on, for example, the initial value of the charge rate and the received current value flowing through the storage battery 3 by means of the current integration method. The control unit 71 stores these current value, temperature, and charge rate of the storage battery 3 in the storage unit 73 as information on the current value, temperature, and charge rate of the storage battery 3 acquired during the target period.

[0036] The method by which the control unit 71 acquires the current value flowing through the storage battery 3, the temperature of the storage battery 3, and the charge rate of the storage battery 3 is not limited to the above-described example. For example, the control unit 71 may communicate with the voltage sensor 6 and calculate the charge rate of the storage battery 3 based on the value of the open-circuit voltage of the storage battery 3.

[0037] In step S3, the control unit 71 determines whether the operation mode is an operation mode for performing charge and discharge or a holding mode for holding power. More specifically described, the control unit 71 determines the operation state of the storage battery 3 based on, for example, at least one of the acquired current value and charge rate. The operation state includes charge, discharge, and holding. If the operation state of the storage battery 3 is holding, the control unit 71 determines that the operation mode is the holding mode. Further, if the operation state of the storage battery 3 is charge or discharge, the control unit 71 determines that the operation mode is the operation mode.

[0038] For example, the control unit 71 may estimate the change in the storage battery 3 by reading and comparing the past current values, charge rates, etc. stored in the storage unit 73, and determine the operating state of the storage battery 3. Also, for example, if the control unit 71 includes a current value whose absolute value is equal to or greater than a predetermined value during the target period, it may be determined that the storage battery 3 is inputting or outputting a power amount equal to or greater than a predetermined amount, and the operation mode is the operation mode. On the other hand, when the current value obtained during the target period does not include a current value whose absolute value is equal to or greater than a predetermined value, the control unit 71 may determine that the storage battery 3 is holding power and the operation mode is the holding mode.

[0039] Here, FIG. 4 is a diagram showing an example of the change in the charge rate of the storage battery 3 over time. Also, FIG. 5 is a diagram showing an example of the operation mode determined corresponding to the change in the charge rate of FIG. 4. The vertical axis of FIG. 4 is the charge rate (SOC) of the storage battery 3. Also, the horizontal axis of FIG. 4 is time, and time points t1, t2, t3, t4, t5, t6,..., tk are shown. k is an integer of 7 or more. The control unit 71 acquires the charge rate at timings including these time points. For example, the control unit 71 determines the operation state as shown in FIG. 5 based on the change in the charge rate of the storage battery 3 at time points t1, t2, t3, t4, t5, t6,.... For example, at time point t1 in FIG. 4, the charge rate has decreased from 100% to about 50%, and the control unit 71 determines that the operation state is discharging as shown in FIG. 5. For example, at time point t2 in FIG. 4, the charge rate remains at about 50% and does not change much, and the control unit 71 determines that the operation state is holding as shown in FIG. 5. For example, at time point t5 in FIG. 4, the charge rate has increased from 10% to about 80%, and the control unit 71 determines that the operation state is charging as shown in FIG. 5. In this way, the control unit 71 determines the operation state of the storage battery 3 at a predetermined time. The predetermined time is time points t1, t2, t3, t4, t5, t6,.... k tk are shown. k is an integer of 7 or more. The control unit 71 acquires the charge rate at timings including these time points. For example, the control unit 71 determines the operation state based on the change in the charge rate of the storage battery 3 at time points t1, t2, t3, t4, t5, t6,.... k Based on the change in the charge rate of the storage battery 3 at time points t1, t2, t3, t4, t5, t6,.... For example, at time point t1 in FIG. 4, the charge rate has decreased from 100% to about 50%, and the control unit 71 determines that the operation state is discharging as shown in FIG. 5. For example, at time point t2 in FIG. 4, the charge rate remains at about 50% and does not change much, and the control unit 71 determines that the operation state is holding as shown in FIG. 5. For example, at time point t5 in FIG. 4, the charge rate has increased from 10% to about 80%, and the control unit 71 determines that the operation state is charging as shown in FIG. 5. In this way, the control unit 71 determines the operation state of the storage battery 3 at a predetermined time. The predetermined time is time points t1, t2, t3, t4, t5, t6,.... kIt is set to include a timing that indicates a change in the charging rate, as shown. The predetermined time is, for example, every 10 minutes. The control unit 71 stores the determined operating state of the storage battery 3 in the storage unit 73 in association with the time at the time of determination. Here, the explanations of "operation mode to be applied", "SOC range", and "application classification" in FIG. 5 will be described later.

[0040] Referring to FIG. 2 again, in step S4, the control unit 71 determines whether or not the operating state of the storage battery 3 has changed. The change in the operating state of the storage battery 3 means that the operating state becomes different from before. The change in the operating state of the storage battery 3 includes changes from charging to discharging or holding, from discharging to holding or charging, and from holding to charging or discharging. When the operating state of the storage battery 3 has changed (Yes in step S4), the control unit 71 executes determination of the variation range of the charging rate and estimation of the degree of deterioration of the storage battery 3.

[0041] Even when the operating state of the storage battery 3 has not changed (No in step S4), in step S5, the control unit 71 determines whether or not a predetermined time has elapsed. When the predetermined time has elapsed (Yes in step S5), the control unit 71 executes determination of the variation range of the charging rate and estimation of the degree of deterioration of the storage battery 3. However, when the predetermined time has not elapsed (No in step S5), the control unit 71 returns to the process of step S2.

[0042] When the control unit 71 determines that the operating state of the storage battery 3 has changed (Yes in step S4), or when it determines that a predetermined time has elapsed (Yes in step S5), the control unit 71 stores the date and time at the determined time in the storage unit 73 as the end date and time of the target period and the start date and time of the next target period.

[0043] In the example of FIG. 4, the times t1, t2, t3, t4, t5, t6,..., t k correspond to the timings of the change in the operating state of the storage battery 3. The control unit 71 determines the times t1, t2, t3, t4, t5, t6,..., t when the operating state of the storage battery 3 is switched kIn this case, the target period is divided. For example, at time t3, the control unit 71 executes determination of the variation range of the charging rate and estimation of the degradation degree of the storage battery 3 for the target period with time t2 as the start date and time and time t3 as the end date and time. Further, for example, at time t4, the control unit 71 executes determination of the variation range of the charging rate and estimation of the degradation degree of the storage battery 3 for the target period with time t3 as the start date and time and time t4 as the end date and time. In the present embodiment, the control unit 71 executes estimation of the degradation degree of the storage battery 3 for a target period delimited by a change in the operating state of the storage battery 3 or delimited at a predetermined time. For example, compared with a method of dividing the target period at the timing when the storage battery 3 is fully charged, since the estimation of the degradation degree of the storage battery 3 is executed for a relatively short target period, the storage battery management device 7 and the storage battery system 1 according to the present embodiment can improve the accuracy of the estimation of the degradation degree of the storage battery 3.

[0044] Referring to FIG. 2 again, in step S6, the control unit 71 determines the variation range of the charging rate of the storage battery 3 in the target period.

[0045] Specifically, the control unit 71 determines the variation range of the charging rate of the storage battery 3 in the target period based on the charging rate included in the information acquired in the target period and stored in the storage unit 73. The control unit 71 extracts the maximum value and the minimum value from the charging rates acquired in the target period, and sets the range from the minimum value to the maximum value as the variation range of the charging rate.

[0046] As shown in FIG. 6, the control unit 71 stores in advance in the storage unit 73 a plurality of operation modes with different SOC ranges. In the example of FIG. 6, a plurality of operation modes (operation modes 1 to 6) corresponding to the operation mode and a plurality of operation modes (operation modes 7 to 11) corresponding to the hold mode are stored in the storage unit 73. The control unit 71 selects one operation mode such that the variation range of the charging rate based on the maximum value and the minimum value extracted in the target period is included in the SOC range. The control unit 71 may store the selected one operation mode in the storage unit 73 in association with the target period.

[0047] For example, at time t1 in FIG. 4, the charge rate has decreased from 100% to about 50%, and the control unit 71 selects operation mode 2 with an SOC range of 40-100 [%] as shown in FIG. 5. As shown in FIG. 6, operation mode 2 is one of a plurality of operation modes corresponding to the operation mode, and defines the exponents and coefficients used in the calculation of normal degradation. For example, at time t2 in FIG. 4, the charge rate remains at about 50% and does not change much, and the control unit 71 selects operation mode 9 with an SOC range of 30-70 [%] as shown in FIG. 5. As shown in FIG. 6, operation mode 9 is one of a plurality of operation modes corresponding to the holding mode, and defines the exponents and coefficients used in the calculation of holding degradation. For example, at time t5 in FIG. 4, the charge rate has increased from 10% to about 80%, and the control unit 71 selects operation mode 1 with an SOC range of 10-100 [%] as shown in FIG. 5. As shown in FIG. 6, operation mode 1 is one of a plurality of operation modes corresponding to the operation mode, and defines the exponents and coefficients used in the calculation of normal degradation.

[0048] Generally, it is known that the battery 3 deteriorates more when the charge rate is near the end of discharge or the end of charge and the battery is operating or holding power than in other cases. Therefore, in the present embodiment, as shown in FIG. 6, a plurality of operation modes corresponding to the variation range of the charge rate are defined, and the exponents and coefficients used in the calculation of the degree of degradation are defined. That is, the correspondence information between the conditions of the operation mode and the degree of degradation of the battery 3 when the battery 3 is operated under those conditions is stored in the storage unit 73 in the form of a table as shown in FIG. 6. By using a plurality of operation modes thus classified into patterns, the control unit 71 can improve the calculation accuracy of the degree of degradation of the battery 3. Here, the number of operation modes and the SOC range of the operation mode are not limited to the example of FIG. 6, and may be arbitrarily determined according to the characteristics of the battery 3. Here, as shown in the item of "application classification" at time t5 and time t k in FIG. 5, when the operation state is charging, rate-dependent degradation may be calculated in addition to normal degradation. Details of rate-dependent degradation will be described later.

[0049] Referring back to FIG. 2, in step S7, the control unit 71 estimates the degree of deterioration of the storage battery 3 during the target period.

[0050] Specifically, the control unit 71 estimates the degree of deterioration of the storage battery 3 during the target period based on the operation mode of the storage battery 3 during the target period stored in the storage unit 73 and the temperature included in the information acquired during the target period.

[0051] In the present embodiment, the control unit 71 calculates the following formula (1) based on Arrhenius' law and uses the calculation result to estimate the degree of deterioration of the storage battery 3. Arrhenius' law is a well-known law used, for example, when predicting the temperature dependence of chemical reaction rates. α = exp((b / T) + c) (1) Here, α: Reaction rate constant, b: Slope, c: Intercept, T: Absolute temperature That is. The coefficient b indicating the slope and the coefficient c indicating the intercept are determined for each operation mode as shown in FIG. 6.

[0052] Using the reaction rate constant α calculated by formula (1), the capacity deterioration of the storage battery 3 is represented by the following formula (2). CAP = α(t) β (2) Here, CAP: Capacity deterioration, α: Reaction rate constant, t: Elapsed time, β: Deterioration index That is.

[0053] In formula (2), the capacity deterioration at a certain elapsed time t is CAP (n-1) And the capacity deterioration at the elapsed time t + Δt after an additional time interval Δt has elapsed from the elapsed time t is CAP n Then, the capacity deteriorations CAP (n-1) And CAP n Are represented by the following formulas (3) and (4), respectively. Also, the capacity deterioration CAP nUsing this, the degree of degradation SOH of the storage battery 3 at the elapsed time t (n-1) and the degree of degradation SOH at the elapsed time t + Δt n satisfy the following relational expressions. That is, the degree of degradation SOH of the storage battery 3 n is calculable from the degree of degradation SOH (n-1) and the capacity degradation CAP n . CAP (n-1) = α(t) β (3) CAP n = α(t + Δt) β (4) SOH n = SOH (n-1) - CAP n Based on the capacity degradation CAP at a certain point in time from Equations (3) and (4), CAP after a time Δt has elapsed from that point (n-1) is represented by the following Equation (5). n CAP n = α((CAP (n-1) ) β + Δt) (1 / β) = f(CAP (n-1) ) (5) Here, α: reaction rate constant, β: degradation index, Δt: time interval, n: natural number of 1 or more is used.

[0054] The reaction rate constant α and the degradation index β in Equation (5) vary depending on the state in which the storage battery 3 is performing charge / discharge or power holding, the state of charge of the storage battery 3, and the temperature of the storage battery 3. Therefore, in this embodiment, based on the degree of degradation of the storage battery 3 measured by operating the storage battery 3 while changing the state of charge, temperature, and operating mode conditions of the storage battery 3, the coefficients and exponents are determined in advance and stored. Specifically, the coefficients and exponents determined in advance are the coefficients (b, c) of the reaction rate constant α and the degradation index β associated with each of the plurality of operating modes shown in FIG. 6.

[0055] Based on the operation mode and temperature, the control unit 71 estimates the degree of deterioration of the storage battery 3 during the target period by referring to the corresponding information.

[0056] Referring to FIG. 3, the details of the estimation process of the degree of deterioration of the storage battery 3 during the target period executed by the control unit 71 will be described. For example, assume that during the target period, the temperatures and current values of X storage batteries 3 are acquired at time intervals Δt. In step S11, the control unit 71 sets the initial value of the degree of deterioration of the storage battery 3 acquired in step 1 as SOH0, and sets 0 as the initial value for the number of repetition times n.

[0057] Next, the control unit 71 repeats the process from step S12 to step S17 X times. That is, the control unit 71 executes the process from step S12 to step S17 for all of the temperatures and current values of the X storage batteries 3 acquired during the target period. As a result, the control unit 71 can calculate the degree of deterioration SOH of the storage battery 3 at each time point n (where n is a natural number from 1 to X) at time intervals Δt from the degree of deterioration SOH0 of the storage battery 3 at the first start time point during the target period. n can be calculated.

[0058] Specifically, in step S12, the control unit 71 increments the number of repetition times n by 1.

[0059] In step S13, the control unit 71 calculates the SOH at the time point when the time Δt×n has elapsed as described above using the coefficient of the selected operation mode. The SOH calculated in step S13 n corresponds to the degree of deterioration of normal deterioration or holding deterioration. Here, for the calculation of the degree of deterioration of normal deterioration or holding deterioration, when the temperatures of a plurality of cells 31 are obtained, the maximum temperature is selected and used without averaging these temperatures. By selecting and using the maximum temperature from the temperatures of the plurality of cells 31, the degree of deterioration SOH of the storage battery 3 n can be calculated more accurately. n can be calculated.

[0060] Here, it is known that the storage battery 3 deteriorates according to the rate and temperature during charging. Therefore, the control unit 71 determines whether the operating state is charging in step S14, and determines whether the average current value is equal to or greater than the threshold value in step S15. The threshold value in step S15 is a reference value for determining that more current is flowing than normal due to the progress of deterioration, and is set according to the type of the storage battery 3 and the like. Also, in step S15, for example, when a plurality of currents are obtained, averaging is performed and the average value is compared with the threshold value.

[0061] When the operating state is charging (Yes in step S14) and the average current value is equal to or greater than the threshold value (Yes in step S15), the control unit 71 calculates the rate-dependent degradation degree. The rate-dependent degradation degree is the degradation degree corresponding to the progress of degradation, and is a value for correcting the normal degradation degree. By including the amount of change according to the temperature due to rate-dependent degradation, the control unit 71 can calculate the degradation degree SOH of the storage battery 3 with high precision. n FIG. 7 shows a table of coefficients and the like for obtaining the amount of change according to the temperature due to rate-dependent degradation in the present embodiment. The control unit 71 extracts the reaction rate constant α and the degradation index β from FIG. 7 based on the operation mode and the temperature, and calculates the rate-dependent degradation degree of the storage battery 3 according to formula (2). Here, in the rate-dependent degradation degree, the rated capacity also changes according to the operation mode, and the calculated value according to formula (2) is adjusted according to the multiplier shown in FIG. 7 (for example, 0.93 in operation mode 1). The rated capacity corresponds to the above-mentioned design capacity in the calculation of the degradation degree. Also, the temperature used in the calculation of the rate-dependent degradation degree is, for example, when a plurality of temperatures of the plurality of cells 31 are obtained, the minimum temperature is selected and used without averaging these. By selecting and using the minimum temperature from the plurality of temperatures of the plurality of cells 31, the rate-dependent degradation degree of the storage battery 3 can be calculated more accurately. 2 ) according to which the calculated value according to formula (2) is adjusted. The rated capacity corresponds to the above-mentioned design capacity in the calculation of the degradation degree. Also, the temperature used in the calculation of the rate-dependent degradation degree is, for example, when a plurality of temperatures of the plurality of cells 31 are obtained, the minimum temperature is selected and used without averaging these. By selecting and using the minimum temperature from the plurality of temperatures of the plurality of cells 31, the rate-dependent degradation degree of the storage battery 3 can be calculated more accurately.

[0062] Referring to FIG. 3 again, the control unit 71 calculates the rate-dependent degradation degree in step S16, and the degradation degree SOH of normal degradation nIt is added thereto. The result after addition becomes the final degree of deterioration. Here, when the operating state is not charging (No in step S14), the rate-dependent degree of deterioration is not calculated, and the degree of deterioration SOH of normal deterioration n becomes the final degree of deterioration. Also, even when the operating state is charging, if the average current value is less than the threshold value (No in step S15), the rate-dependent degree of deterioration is not calculated, and the degree of deterioration SOH n of normal deterioration becomes the final degree of deterioration. The control unit 71 sets the final degree of deterioration SOH n as the degree of deterioration of the storage battery 3 at time point n and stores it in the storage unit 73.

[0063] In step S17, the control unit 71 determines whether or not the deterioration degree estimation process from step S12 to step S17 has been repeated X times. If it is determined that the deterioration degree estimation process has not been repeated X times (No in step S17), the control unit 71 repeats the process from step S12. On the other hand, if it is determined that the deterioration degree estimation process has been repeated X times (Yes in step S17), the control unit 71 sets the degree of deterioration SOH X of the storage battery 3 at time point X as the degree of deterioration of the storage battery 3 at the end time point of the target period and stores it in the storage unit 73. The control unit 71 may output the estimated degree of deterioration of the storage battery 3 to the output unit 74.

[0064] Referring to FIG. 2 again, when step S7 ends, the control unit 71 ends this process. After ending this process, the control unit 71 may start the process from step S1 again.

[0065] As described above, the storage battery management device, storage battery system, and storage battery management method according to the present embodiment can estimate the degree of deterioration of the storage battery with high accuracy by the above-described configuration and steps.

[0066] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included within the scope of the present disclosure. For example, functions included in each component or each step, etc., can be rearranged so as not to be logically contradictory, and a plurality of components or steps, etc., can be combined into one or divided. The embodiments according to the present disclosure can also be realized as a program executed by a processor included in the device or a storage medium storing the program. It should be understood that these are also included within the scope of the present disclosure.

[0067] For example, in the above-described embodiment, the battery system 1 has been described as including one current sensor 4, temperature sensor 5, and voltage sensor 6 each, but this is not the only case. The battery system 1 may include a plurality of current sensors 4, temperature sensors 5, or voltage sensors 6. For example, in the battery system 1, the current sensor 4, temperature sensor 5, or voltage sensor 6 is not limited to each battery 3, and may be provided for each cell 31 or each battery module 32. In such a case, the battery management device 7 may calculate the current value, temperature, or voltage of the battery 3 by calculating an average value or representative value, etc., from the values measured by the plurality of current sensors 4, temperature sensors 5, or voltage sensors 6.

[0068] Alternatively, in the above-described embodiment, all or part of the functions or processes described as the functions or processes of the battery management device 7 may be realized as the functions or processes of a computer such as a smartphone or a personal computer. Specifically, a program describing the processing contents for realizing each function of the battery management device 7 according to the embodiment can be stored in the memory of the computer, and the program can be read and executed by the processor of the computer. Therefore, the processing of the battery management device 7 according to the present embodiment can also be realized as a program executable by the processor.

[0069] Alternatively, in the above-described embodiment, although an example in which the battery management device 7 is provided separately from the power conditioner 2 and the battery 3 has been shown, this is not the case in all instances. The power conditioner 2 or the battery 3 may function as the battery management device 7. Alternatively, an EMS (Energy Management System) such as a HEMS (Home Energy Management System) and a BEMS (Building Energy Management System) may function as the battery management device 7. In such a case, the power conditioner 2, the battery 3, or the EMS may be configured to mount a computer having the above-described configuration and functions as the configuration and functions of the battery management device 7.

Description of Reference Numerals

[0070] 1 Battery system 2 Power conditioner (PCS) 3 Battery 31 Cell 32 Battery module 4 Current sensor 5 Temperature sensor 6 Voltage sensor 7 Battery management device (BMS) 71 Control unit 72 Communication unit 73 Memory unit 74 Output unit 75 Input unit 8 Power system 9 Load

Claims

1. During a target period, obtain the current value flowing through the storage battery, the temperature of the storage battery, and the charging rate of the storage battery, determine the operating mode of the storage battery during the target period based on the current value and the charging rate, and estimate the degradation degree of the storage battery during the target period based on the operating mode and the temperature, comprising a control unit, The control unit divides the target period at the timing when the operating state of the storage battery is switched, The target period is divided by switching the operating state of the storage battery, which consists of any one of charging, discharging, and holding, a storage battery management device.

2. Further comprising a storage unit that stores correspondence information between the conditions of the operating mode for operating the storage battery and the degradation degree of the storage battery when the storage battery is operated under the conditions, The control unit estimates the degradation degree of the storage battery during the target period based on the correspondence information, the storage battery management device according to claim 1.

3. In determining the operating mode, the control unit determines whether the operating mode is an operating mode for performing charge and discharge or a holding mode for holding power, the storage battery management device according to claim 1 or 2.

4. In determining the operating mode, the control unit determines the variation range of the charging rate of the storage battery during the target period, the storage battery management device according to claim 1 or 2.

5. When it is determined that the operating state of the storage battery is charging, in estimating the degradation degree, the control unit adds a change amount corresponding to the temperature, the storage battery management device according to claim 1 or 2.

6. When it is determined that the operating state of the storage battery is charging, in estimating the degradation degree, the control unit changes the rated capacity according to the operating mode, the storage battery management device according to claim 1 or 2.

7. Including a storage battery and a storage battery management device comprising a control unit, The control unit is, During a target period, obtain the current value flowing through the storage battery, the temperature of the storage battery, and the charging rate of the storage battery, Based on the current value and the charging rate, determine the operating mode of the storage battery during the target period, Estimate the degradation degree of the storage battery during the target period based on the operating mode and the temperature, The control unit divides the target period at the timing when the operating state of the storage battery is switched, The battery system, wherein the target period is divided by switching the operating state of the battery, which consists of any one of charging, discharging, and holding.

8. A battery management method executed by a battery management device having a control unit, wherein the control unit acquires a current value flowing through the battery, the temperature of the battery, and the state of charge of the battery in a target period; determines an operation mode of the battery in the target period based on the current value and the state of charge; estimates a degree of deterioration of the battery in the target period based on the operation mode and the temperature, and the battery management method further includes a step in which the control unit divides the target period at a timing when the operating state of the battery is switched, wherein the target period is divided by switching the operating state of the battery, which consists of any one of charging, discharging, and holding.

9. In a target period, a current value flowing through a battery, the temperature of the battery, and the state of charge of the battery are acquired, an operation mode of the battery in the target period is determined based on the current value and the state of charge, and a degree of deterioration of the battery in the target period is estimated based on the operation mode and the temperature. A control unit is provided, wherein the target period is divided by switching the operating state of the battery including charging, discharging, and holding, and when it is determined that the operating state of the battery is charging, the control unit changes a rated capacity according to the operation mode in the estimation of the degree of deterioration.

10. A battery system including a battery and a battery management device having a control unit, wherein the control unit acquires a current value flowing through the battery, the temperature of the battery, and the state of charge of the battery in a target period; determines an operation mode of the battery in the target period based on the current value and the state of charge; estimates a degree of deterioration of the battery in the target period based on the operation mode and the temperature; wherein the target period is divided by switching the operating state of the battery including charging, discharging, and holding, and when it is determined that the operating state of the battery is charging, the control unit changes a rated capacity according to the operation mode in the estimation of the degree of deterioration.

11. A battery management method executed by a battery management device having a control unit, wherein the control unit During a target period, obtaining a current value flowing through the storage battery, a temperature of the storage battery, and a charge rate of the storage battery; Determining an operation mode of the storage battery during the target period based on the current value and the charge rate; Estimating a degree of deterioration of the storage battery during the target period based on the operation mode and the temperature, and including: The target period is divided by switching of an operation state of the storage battery including charging, discharging, and holding; A storage battery management method, further including a step in which, when it is determined that the operation state of the storage battery is charging, the control unit changes a rated capacity according to the operation mode in the estimation of the degree of deterioration.

Images