Battery management device, battery management method, and power storage system

Abstract

A battery management device (102) calculates a state of charge (SOC), a degree of charge deterioration (SOHQ), and a degree of resistance deterioration (SOHR), which indicate the state of charge of a rechargeable battery, corrects the calculated SOHR, corrects an intermediate resistance (MidDCR) corresponding to an intermediate voltage (MidVoltage) in accordance with a correction factor corresponding to SOHR for MidDCR (corrected SOHR), and controls the state of charge (SOC), the degree of charge deterioration (SOHQ), and the degree of resistance deterioration (SOHR). MidVolage (an intermediate voltage present between a voltage value indicating a discharge voltage in a current state of charge of the battery and a voltage value indicating a discharge voltage in a minimum state of charge of the battery) is calculated, the remaining capacity of the battery is calculated from SOC and SOHQ, and the available energy of the battery is calculated from the intermediate voltage and the remaining capacity.

Description

This application is a divisional application of the following application, Application Date of the Original Application: September 18, 2020, Application Number of the Original Application: 202080099398.2, Inventive Title of the Original Application: Battery Management Device, Battery Management Method, and Power Storage System. TECHNICAL FIELD

[0001] The present application relates to a battery management device, a battery management method, and a power storage system. BACKGROUND

[0002] In recent years, from the viewpoint of global warming, power generation using renewable energy such as sunlight and wind power and the use of a power storage system (BESS) to seek stabilization of output of the power generation and transmission system are expanding. In addition, in mobile transportation systems such as automobiles, such a power storage system is widely used from the viewpoint of emission restrictions.

[0003] A general power storage system of the related art is configured with a battery in which a plurality of battery cells are combined, a cooling system that cools the battery to perform temperature adjustment, and a battery management device that performs charge and discharge control of the battery to maintain the system in a safe state.

[0004] In a power storage system mounted in an electric vehicle or a hybrid vehicle, in order to seek optimization of vehicle control while maintaining the battery in a safe state, the state of charge (SOC), the state of health (SOH), the maximum allowable power, and the like of the battery must be accurately found. These battery states are found from measured values of current, voltage, temperature, and the like given by sensors. One of the battery states used in such a power storage system is the available energy. The available energy indicates the total amount of electric energy remaining in the battery and corresponds to the electric energy that the battery can release before reaching the allowable use limit. This available energy is used, for example, for calculation of the travelable distance of the vehicle until the battery becomes a fully discharged (use limit) state.

[0005] Regarding the calculation of the available energy of the battery, the technology described in Patent Literature 1 is known. Patent Literature 1 discloses a method of obtaining the initial available energy of the battery, calculating the cumulative energy consumption of the battery during travel of the vehicle for the current cumulative travel distance, calculating the remaining available energy of the battery from these values, and calculating the final power consumption at the current cumulative travel distance, thereby calculating the travelable distance of the vehicle. PRIOR ART DOCUMENTS PATENT LITERATURE

[0006] Patent Literature 1: US Patent No. 9037327 Specification SUMMARY PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In the method of Patent Literature 1, accumulation of errors of the voltage sensor and the current sensor occurs when the cumulative energy consumption of the battery is calculated. Therefore, it will be difficult to accurately estimate the available energy of the battery, especially in a case where the vehicle has traveled a long distance. TECHNICAL MEANS FOR SOLVING THE PROBLEMS

[0008] The battery management device of the present application manages a chargeable and dischargeable battery, and includes a battery state calculation section that calculates a state of charge, a capacity deterioration degree, and a resistance deterioration degree of the battery; an intermediate voltage calculation section that corrects the calculated resistance deterioration degree, corrects an intermediate resistance of the battery corresponding to the intermediate voltage in accordance with a correction coefficient corresponding to the corrected resistance deterioration degree, and calculates an intermediate voltage between a charge and discharge voltage at a current state of charge of the battery and a charge and discharge voltage at a minimum state of charge or a maximum state of charge of the battery based on the corrected intermediate resistance; a remaining capacity calculation section that calculates a remaining capacity or a chargeable capacity of the battery based on the state of charge and the capacity deterioration degree; and an available energy calculation section that calculates an available energy or a chargeable energy of the battery based on the intermediate voltage and the remaining capacity or the intermediate voltage and the chargeable capacity.

[0009] The battery management method of the present application is a method for managing a chargeable and dischargeable battery, and calculates a state of charge, a capacity deterioration degree, and a resistance deterioration degree of the battery by means of a computer, corrects the calculated resistance deterioration degree, corrects an intermediate resistance of the battery corresponding to the intermediate voltage in accordance with a correction coefficient corresponding to the corrected resistance deterioration degree, calculates an intermediate voltage between a charge and discharge voltage at a current state of charge of the battery and a charge and discharge voltage at a minimum state of charge or a maximum state of charge of the battery based on the corrected intermediate resistance, calculates a remaining capacity or a chargeable capacity of the battery based on the calculated state of charge and the capacity deterioration degree, and calculates an available energy or a chargeable energy of the battery based on the calculated intermediate voltage and the remaining capacity or the calculated intermediate voltage and the chargeable capacity.

[0010] The power storage system of the present application includes a battery management device, a chargeable and dischargeable battery, and a charge and discharge device that performs charge and discharge of the battery in accordance with an available energy or a chargeable energy of the battery calculated by the battery management device. EFFECTS OF THE INVENTION

[0011] According to the present application, the available energy of the battery can be accurately estimated. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of an embodiment of the power storage system of the present invention. Figure 2 This is a diagram illustrating available energy. Figure 3 This is a conceptual diagram of a method for calculating available energy according to one embodiment of the present invention. Figure 4 A diagram illustrating the functional blocks of a battery management device related to the calculation of available energy in the first embodiment of the present invention. Figure 5 A diagram showing the function blocks of the battery state calculation unit. Figure 6 A diagram illustrating an example of the equivalent circuit of a battery cell in a battery model. Figure 7 This diagram illustrates the functional blocks of the intermediate voltage calculation unit in the first embodiment of the present invention. Figure 8 An example of h (an element reflected in SOHR) representing the individual temperature of different batteries. Figure 9 A diagram illustrating the functional blocks of the battery management device related to the available energy calculation process in the second embodiment of the present invention. Figure 10 This diagram illustrates the functional blocks of the intermediate voltage calculation unit in the second embodiment of the present invention. Figure 11 This diagram illustrates the functional blocks of the battery management device related to the available energy calculation process in the third embodiment of the present invention. Figure 12 This diagram illustrates the functional blocks of the intermediate voltage calculation unit in the third embodiment of the present invention. Detailed Implementation

[0013] The embodiments of the present invention will now be described. (First Embodiment)

[0014] Figure 1 This is a schematic diagram of an embodiment of the power storage system of the present invention. Figure 1 The illustrated Power Storage System (BESS) 1 includes a battery pack 101, a battery management device 102, a current sensor 103, a unit controller 104, a voltage sensor 105, a temperature sensor 106, and a relay 107. The Power Storage System 1 is connected to a load 3 such as an AC motor via a converter 2. The Power Storage System 1 and the converter 2 are connected to a host controller 4 via a communication line (not shown).

[0015] The battery pack 101 is configured by connecting a plurality of battery cells capable of charging and discharging in series and parallel. When the load 3 is driven, direct current discharged from the battery pack 101 is converted into alternating current by the inverter 2 and supplied to the load 3. Further, when the load 3 is regenerated, alternating current output from the load 3 is converted into direct current by the inverter 2 and charged into the battery pack 101. Charging and discharging of the battery pack 101 is performed by the operation of the inverter 2. The operation of the inverter 2 is controlled by the upper controller 4.

[0016] The current sensor 103 detects a current flowing to the battery pack 101 and outputs the detection result to the battery management device 102. The cell controller 104 detects a voltage of each battery cell of the battery pack 101 and outputs the detection result to the battery management device 102. The voltage sensor 105 detects a voltage (total voltage) of the battery pack 101 and outputs the detection result to the battery management device 102. The temperature sensor 106 detects a temperature of the battery pack 101 and outputs the detection result to the battery management device 102. The relay 107 switches a connection state between the power storage system 1 and the inverter 2 according to the control of the upper controller 4.

[0017] The battery management device 102 performs charging and discharging control of the battery pack 101 on the basis of each detection result of the current sensor 103, the cell controller 104, the voltage sensor 105, and the temperature sensor 106. At this time, the battery management device 102 calculates each kind of battery state as an index indicating a state of the battery pack 101. The battery state calculated by the battery management device 102 includes, for example, a state of charge (SOC) (specifically, for example, a charge rate of the battery), a state of health (SOH) (specifically, for example, a degree of deterioration of the battery), a maximum allowable power, available energy, and the like. By using these battery states, the battery management device 102 can safely control the battery pack 101. As a result, the upper system (electric vehicle, hybrid vehicle, or the like) in which the power storage system 1 is mounted can be efficiently controlled. The battery management device 102 and the upper controller 4 communicate information necessary for the charging and discharging control of the battery pack 101.

[0018] Further, in the present embodiment, the above-mentioned so-called available energy is defined as a total amount of electric energy that the battery pack 101 can release among electric energy accumulated in the battery pack 101. This corresponds to a total of electric energy (Wh) that each battery cell can release in a case where the SOC of each battery cell becomes a minimum SOC value (SOCmin) allowed for each battery cell while the battery pack 101 is caused to discharge at a certain discharge current I C0,DCh At the time of discharging, the SOC of each battery cell becomes a minimum SOC value (SOCmin) allowed for each battery cell, and the available energy is a total of electric energy (Wh) that each battery cell can release in a case where each battery cell can release the electric energy without falling below a prescribed minimum voltage V min At the time of discharging, the SOC of each battery cell becomes a minimum SOC value (SOCmin) allowed for each battery cell, and the available energy is a total of electric energy (Wh) that each battery cell can release in a case where each battery cell can release the electric energy without falling below a prescribed minimum voltage V min At the time of discharging, the SOC of each battery cell becomes a minimum SOC value (SOCmin) allowed for each battery cell, and the available energy is a total of electric energy (Wh) that each battery cell can release in a case where each battery cell can release the electric energy without falling below a prescribed minimum voltage V C0,DChIt is preset according to the usage mode of the power storage system 1, etc.

[0019] Figure 2 This is a diagram illustrating available energy. Figure 2 In the diagram, the dashed line indicated by symbol 700 represents the SOC-OCV curve, which shows the relationship between the State of Charge (SOC) and Open Circuit Voltage (OCV) of each battery cell in battery pack 101. Furthermore, the solid line indicated by symbol 701 represents the discharge current I of each battery cell in battery pack 101. C0,DCh Discharge from the current SOC to the current SOC min The discharge curve at that point. Furthermore, Figure 2 The dashed line 703 represents the current SOC, and the dashed line 705 represents the SOC. min .

[0020] Discharge curve 701 illustrates the relationship between the State of Charge (SOC) and Closed-Circuit Voltage (CCV) of each battery cell in battery pack 101 during discharge. Specifically, it ensures that the CCV of each battery cell during discharge of battery pack 101 follows discharge curve 701 and is not lower than the minimum voltage V shown by dotted line 707. min Within a range, the voltage value 704 corresponding to the current SOC continuously varies to the SOC at the end of the discharge. min The corresponding voltage value is up to 706.

[0021] Here, if we represent the C-rate during discharge corresponding to discharge curve 701 as C0, then the discharge current I... C0,DCh It can be represented as I C0,DCh =C0×Ah rated In this formula, Ah rated This indicates the rated capacity of each battery cell.

[0022] Furthermore, the available energy of each battery cell during discharge is defined by the following (Equation 1). [Formula 1]

[0023] In Equation 1, CCV(t) represents the CCV, i.e., the discharge voltage, of each battery cell at time t. present Indicates the current time, t end This indicates that the SOC of each battery has reached its maximum SOC. min And the moment when the discharge ends. Equation 1 represents... Figure 2 The diagram shows the process from the current SOC to the current SOC. min The integral value of the discharge curve 701 up to that point. That is, Figure 2 The area of ​​region 702, enclosed by the discharge curves 701, 703, and 705 and represented by shadow lines, is equivalent to the available energy of each battery cell.

[0024] For example, when the energy storage system 1 is installed in a vehicle, the available energy of the battery pack 101 must be calculated in real time to achieve proper and safe vehicle control. However, during vehicle operation, the current changes gradually, so a fixed discharge current I cannot be used. C0,DCh The formula based on this premise is (Equation 1). Therefore, in one embodiment of the present invention, the available energy of the battery pack 101 can be calculated directly and in real time without using (Equation 1) by means of the calculation method described below.

[0025] Figure 3 This is a conceptual diagram of a method for calculating available energy according to one embodiment of the present invention. Figure 3 In the middle, the SOC-OCV curve 700 and the discharge curve 701 are compared with... Figure 2 The corresponding terms in the text are as follows. Figure 3 In addition to these curves, the diagram also shows region 708, indicated by shaded lines. Region 708 is defined as the following rectangular area: based on the remaining capacity of each battery cell, i.e., the current State of Charge (SOC) and the State of Charge (SOC). min The difference ΔSOC is the longer side, representing the voltage value 704 corresponding to the current SOC and the SOC corresponding to the end of discharge on the discharge curve 701. min The intermediate voltage 710 between the voltage values ​​706 and 706 is the short side.

[0026] In one embodiment of the present invention, Figure 3 The area of ​​region 708 and Figure 2 The intermediate voltage 710 present on the discharge curve 701 is obtained by consistently calculating the area of ​​region 702. In this way, the area of ​​the rectangular region 708 can be calculated by multiplying the intermediate voltage 710 by the remaining capacity (ΔSOC), thereby calculating the... Figure 2 The area of ​​region 702 can be used for energy.

[0027] Furthermore, Figure 3 In the diagram, point 709 on the SOC-OCV curve 700 represents the OCV value (intermediate OCV) corresponding to the intermediate voltage 710. This intermediate OCV represents the OCV value at the current SOC and is related to the SOC. min The values ​​of OCV are between the current SOC and the intermediate SOC. Furthermore, point 711 on the horizontal axis represents the SOC value (intermediate SOC) corresponding to the intermediate voltage 710 and the intermediate OCV. This intermediate SOC lies between the current SOC and the intermediate SOC. min between.

[0028] Furthermore, the method for calculating the usable energy of a single battery cell has been described above. In this embodiment, it is preferable to calculate the usable energy of the entire battery pack 101. For example, the usable energy can be calculated on a per-cell basis for each battery cell constituting the battery pack 101, and the calculated results of the usable energy of each battery cell can be summed to obtain the usable energy of the entire battery pack 101. Alternatively, the above calculation method can be applied to the entire battery pack 101 to calculate the usable energy per unit of the battery pack 101.

[0029] Next, the method for calculating the available energy of this embodiment, which embodies the above concepts, will be explained.

[0030] Figure 4 This diagram illustrates the functional blocks of a battery management device 102 related to the available energy calculation process according to the first embodiment of the present invention. The battery management device 102 of this embodiment includes functional blocks such as a battery state calculation unit 501, an intermediate voltage calculation unit 502, a remaining capacity calculation unit 503, and an available energy calculation unit 504. These functional blocks are implemented, for example, by executing a predetermined program in a computer.

[0031] The battery state calculation unit 501 acquires the current I, closed-circuit voltage CCV, and battery temperature T detected during the charging and discharging of the battery pack 101 from the current sensor 103, voltage sensor 105, and temperature sensor 106, respectively. cell Then, based on this information, the open-circuit voltage OCV, state of charge SOC, polarization voltage Vp, capacity reduction SOHQ (specifically, for example, capacity degradation rate (e.g., a case of degradation degree)), and internal resistance increase SOHR (specifically, for example, the rate of increase of internal resistance, in other words, the degradation rate of internal resistance (e.g., a case of degradation degree)) representing the current state of the battery pack 101 are calculated. Furthermore, details of the method by which the battery state calculation unit 501 calculates these state values ​​will be provided later. Figure 5 Let me explain.

[0032] The intermediate voltage calculation unit 502 acquires the state of charge (SOC) and the increase in internal resistance (SOHR) from the various state values ​​of the battery pack 101 calculated by the battery state calculation unit 501, and acquires the battery temperature (T) from the temperature sensor 106. cell Then, based on this information, the following calculations are performed. Figure 3 The intermediate voltage 710 has been explained. Furthermore, details regarding the calculation method of the intermediate voltage by the intermediate voltage calculation unit 502 will be provided later. Figure 7 Let me explain.

[0033] The remaining capacity calculating section 503 acquires the state of charge SOC and the charge capacity reduction amount SOHQ among the state values of the battery pack 101 calculated by the battery state calculating section 501. Then, the remaining capacity of the battery pack 101 at the current time point is calculated based on these acquired information. Further, the details of the method of calculating the remaining capacity by the remaining capacity calculating section 503 will be described later.

[0034] The available energy calculating section 504 calculates the available energy of the battery pack 101 based on the intermediate voltage calculated by the intermediate voltage calculating section 502 and the remaining capacity calculated by the remaining capacity calculating section 503. Specifically, the available energy of the battery pack 101 is calculated by multiplying the intermediate voltage by the remaining capacity as shown in the following (Formula 2).

[0035] Available energy (Wh) = Intermediate voltage (V) x Remaining capacity (Ah) (Formula 2)

[0036] The available energy of the battery pack 101 calculated by the battery management device 102 is transmitted from the battery management device 102 to the upper controller 4, and is used for the control of the inverter 2 and the like. Thus, the available energy of the battery pack 101 is calculated in real time in the power storage system 1 to perform the charge and discharge control of the battery pack 101.

[0037] Figure 5 A diagram showing the functional blocks of the battery state calculating section 501. The battery state calculating section 501 is provided with a battery model section 601 and a deterioration state detecting section 602.

[0038] The battery model section 601 stores a battery model obtained by modeling the battery pack 101, and uses the battery model to calculate the open circuit voltage OCV, the state of charge SOC, and the polarization voltage Vp. The battery model in the battery model section 601 is set, for example, based on the series number and the parallel number of the battery cells in the actual battery pack 101, and the equivalent circuit of each battery cell. The battery model section 601 calculates the current I, the closed circuit voltage CCV, and the battery temperature T cell The battery model is applied to this, whereby the open circuit voltage OCV, the state of charge SOC, and the polarization voltage Vp corresponding to the state of the battery pack 101 can be calculated.

[0039] Figure 6 A diagram showing an example of the equivalent circuit of the battery cell in the battery model set in the battery model section 601. Figure 6The equivalent circuit of the battery cell shown is constructed by connecting an open-circuit voltage source 603, an internal resistor 604, and a polarization model in series. The open-circuit voltage source 603 has a voltage value Voc, the internal resistor 604 has a resistance value Ro, and the polarization model is a parallel circuit of a polarization capacitor 605 with a capacitance value Cp and a polarization resistor 606 with a resistance value Rp. In this equivalent circuit, the voltage across the open-circuit voltage source 603, i.e., the voltage value Voc, is equivalent to the open-circuit voltage OCV, and the voltage across the parallel circuit of polarization capacitor 605 and polarization resistor 606 is equivalent to the polarization voltage Vp. Furthermore, the value obtained by adding the applied voltage I×Ro of the internal resistor 604 when a current I flows through this equivalent circuit, the polarization voltage Vp, and the open-circuit voltage OCV is equivalent to the closed-circuit voltage CCV. Furthermore, Figure 6 The values ​​of the circuit constants in the equivalent circuit are based on the battery temperature T. cell Therefore, in the battery model section 601, the current I, closed-circuit voltage CCV, and battery temperature T can be used based on these relationships. cell The open-circuit voltage OCV and polarization voltage Vp in the entire battery pack 101 are calculated, and the state of charge SOC is then calculated using the result of the open-circuit voltage OCV.

[0040] return Figure 5 The degradation state detection unit 602 detects the degradation state of the battery pack 101 and calculates the corresponding decrease in charging capacity (SOHQ) and increase in internal resistance (SOHR). Each battery cell in the battery pack 101 degrades continuously due to repeated charging and discharging, resulting in a decrease in charging capacity and an increase in internal resistance. The degradation state detection unit 602, for example, stores information in advance indicating the relationship between the current, voltage, and temperature of the battery pack 101 and the degradation state. Using this information, it calculates the current I, closed-circuit voltage CCV, and battery temperature T obtained from the current sensor 103, voltage sensor 105, and temperature sensor 106, respectively. cell The degradation state of battery pack 101 is detected. Then, based on the pre-stored relationship between degradation state and the decrease in charging capacity SOHQ and the increase in internal resistance SOHR, the decrease in charging capacity SOHQ and the increase in internal resistance SOHR corresponding to the detection result of the degradation state of battery pack 101 can be calculated.

[0041] As explained above, the internal resistance increases due to the degradation state of the battery pack 101. Given the initial resistance value of the internal resistance as Ro,new and the resistance value of the internal resistance at the current time t as Ro(t), the increase in internal resistance SOHR(t) at the current time t is represented by the following equation (3).

[0042] SOHR(t) = {Ro(t) / Ro,new} x 100 (Equation 3)

[0043] Figure 7 A diagram showing the functional blocks of the intermediate voltage calculating section 502 of the first embodiment of the application. The intermediate voltage calculating section 502 is provided with an intermediate OCV table 607, an intermediate DCR table 608, a discharge current setting section 609, and a SOHR correction section 1610.

[0044] The state of charge SOC obtained from the battery state calculating section 501 and the battery temperature T cell are input to the intermediate OCV table 607 and the intermediate DCR table 608, respectively. The intermediate OCV table 607 and the intermediate DCR table 608 respectively obtain the intermediate OCV and the intermediate DCR corresponding to the state of the current battery pack 101 by table search based on the input information. Further, the intermediate DCR is the direct current resistance value of the battery pack 101 corresponding to the intermediate voltage.

[0045] In the intermediate OCV table 607, a MidOCV representing the value of the intermediate OCV is set for each combination of the state of charge SOC and the battery temperature T cell . For example, if the value of the battery temperature T cell is represented as T i (i = 1 ~ p) and the value of the state of charge SOC is represented as SOC j (j = 1 ~ q), p x q voltage values MidOCV i,j (V) are set in the intermediate OCV table 607 for each combination of them.

[0046] MidOCV i,j = MidOCV(T i , SOC j ) (Equation 4)

[0047] In the intermediate DCR table 608, a MidDCR representing the value of the intermediate DCR is set for each combination of the state of charge SOC and the battery temperature T cell . For example, if the value of the battery temperature T cell is represented as T i (i = 1 ~ p) and the value of the state of charge SOC is represented as SOC j (j = 1 ~ q), p x q resistance values MidDCR i,j (Ω) are set in the intermediate DCR table 608 for each combination of them.

[0048] MidDCR i,j = MidDCR(T i, SOC j ) (Formula 5)

[0049] In addition, 1 ≤ i ≤ p and 1 ≤ j ≤ q. The values of MidOCV i,j in the intermediate OCV table 607 and the values of MidDCR i,j in the intermediate DCR table 608 can be set in advance based on the results of analysis of the results of discharge tests on the battery pack 101 or the results of simulation using an equivalent circuit model of the battery pack 101, or the like. For example, these values set in advance can be written into a non-illustrated memory possessed by the battery management device 102, whereby the intermediate OCV table 607 and the intermediate DCR table 608 are formed within the battery management device 102. Further, it is also possible to perform experiments on discharge at C rates at the design stage of the power storage system, and to obtain the voltage value MidOCV i,j and the resistance value MidDCR i,j from the current value, the voltage value, and the battery temperature obtained from the current sensor 103, the voltage sensor 105, and the temperature sensor 106, respectively, in the experiments. Although illustration is omitted, the intermediate DCR table 608 can have the resistance value MidDCR i,j for both Ro and Rp.

[0050] The intermediate voltage calculating section 502 acquires the voltage value MidOCV i,j and the resistance value MidDCR i,j indicated by (Formula 4) and (Formula 5), respectively, from the intermediate OCV table 607 and the intermediate DCR table 608, respectively, corresponding to the input charge state SOC of the current battery pack 101 and the battery temperature T cell . Then, the intermediate voltage MidVoltage(t) is calculated by (Formula 6) below, based on the acquired values, the discharge current I C0,DCh set in advance in the discharge current setting section 609, and the SOHR for MidDCR (corrected SOHR) input from the SOHR correcting section 1610. Figure 3

[0051] MidVoltage(t) = MidOCV(t) - I C0,DCh x MidDCR(t) x SOHR for MidDCR(t) / 100 (Formula 6)

[0052] ​In Expression 6, MidVoltage(t) represents the value of the intermediate voltage at the current time t. Further, MidOCV(t) and MidDCR(t) represent the values of the intermediate OCV and the intermediate DCR at the current time t, respectively, which are acquired from the intermediate OCV table 607 and the intermediate DCR table 608, respectively. SOHR for MidDCR(t) is the value of the internal resistance increase amount SOHR calculated by the battery state calculating section 501 at the time t, which is corrected by the SOHR correcting section 1610, and represents the SOHR value for the correction of the intermediate DCR (MidDCR). An example of the open-circuit intermediate voltage (the open-circuit intermediate voltage corresponding to the intermediate voltage) at the current time t is MidOCV(t). An example of the intermediate voltage drop (the potential difference between the both ends of the battery due to the intermediate DCR when a predetermined charge / discharge current is caused to flow) at the current time t is "I C0,DCh × MidDCR(t) x SOHR for MidDCR(t) / 100" in Expression 6. The SOHR correcting section 1610 will be described later.

[0053] Further, MidOCV(t) and MidDCR(t) in Expression 6 are also the values of the intermediate OCV and the intermediate DCR corresponding to the current state of charge SOC and the battery temperature T cell may be acquired by interpolation from the intermediate OCV table 607 and the intermediate DCR table 608, respectively. For example, interpolation using various interpolation methods such as linear interpolation, Lagrange interpolation, nearest neighbor interpolation, and the like, which are well known, can be performed. Thus, for combinations of the state of charge SOC and the battery temperature T cell for which the intermediate OCV table 607 and the intermediate DCR table 608 do not record appropriate voltage values and resistance values can also be calculated as the intermediate OCV and the intermediate DCR.

[0054] For example, the values of the state of charge SOC and the battery temperature T cell at the time t are represented as SOC(t) and T cell (t), respectively, and they satisfy the following (Expression 7), respectively. In this case, MidOCV(t) and MidDCR(t) corresponding to the combination of SOC(t) and T cell (t) are not recorded in the intermediate OCV table 607 and the intermediate DCR table 608.

[0055] T i <T cell (t) < T i+1 SOC j <SOC(t) < SOC j+1 (Expression 7)

[0056] In the above case, the intermediate voltage calculating section 502 can use four kinds of voltage values of four combinations of T i or T i+1 and SOC j or SOC j+1 in the intermediate OCV table 607, i.e., MidOCV i,j , MidOCV i+1,j , MidOCV i,j+1 , and MidOCV i+1,j+1 respectively corresponding to T cell (t), MidOCV i,j , MidOCV i+1,j , MidOCV i,j+1 , and MidOCV i+1,j+1 to calculate MidOCV(t) at time t by interpolation.

[0057] MidOCV(t) = f(SOC(t), T cell (t), MidOCV i,j , MidOCV i+1,j , MidOCV i,j+1 , MidOCV i+1,j+1 ) (Equation 8)

[0058] Further, the intermediate voltage calculating section 502 can use four kinds of resistance values of four combinations of T i or T i+1 and SOC j or SOC j+1 in the intermediate DCR table 608, i.e., MidDCR i,j , MidDCR i+1,j , MidDCR i,j+1 , and MidDCR i+1,j+1 respectively corresponding to T cell (t), MidDCR i,j , MidDCR i+1,j , MidDCR i,j+1 , and MidDCR i+1,j+1 to calculate MidDCR(t) at time t by interpolation.

[0059] MidDCR(t) = g(SOC(t), T cell (t), MidDCR i,j , MidDCR i+1,j , MidDCR i,j+1 , MidDCR i+1,j+1 ) (Equation 9)

[0060] In the above (Equation 8), (Equation 9), f, g represent interpolation processes performed on the intermediate OCV table 607 and the intermediate DCR table 608, respectively. The contents of these processes differ depending on the interpolation method at the time of interpolation.

[0061] The SOHR correction unit 1610 will be described in detail. The SOHR correction unit 1610 corrects the SOHR to improve the accuracy of the calculated available energy. The inventors of this application have diligently researched the practical application of a battery management device capable of calculating the available energy of the battery pack 101 in real time, and have obtained the following insights. That is, as... Figure 6 As shown, the equivalent circuit of the battery cell has two types of resistors: an internal resistor 604 and a polarization resistor 606. The internal resistor 604 has a resistance value Ro, and the polarization resistor 606 has a resistance value Rp. Both resistors degrade under repeated charging and discharging of the battery pack 101 and at least one ambient condition. Furthermore, the degradation mechanism of the internal resistor 604 with resistance value Ro is not entirely the same as the degradation mechanism of the polarization resistor 606 with resistance value Rp (for example, it differs depending on the characteristics of the battery cell (e.g., depending on the materials used in the battery cell)). SOHR depends not only on Ro but also on Rp. Therefore, the SOHR conforming to (Equation 3) may not be a sufficiently accurate value for calculating the intermediate DCR (MidDCR) after resistance degradation. Therefore, in this embodiment, a SOHR correction unit 1610 is provided. The SOHR correction unit 1610 corrects the SOHR calculated by the battery state calculation unit 501. Specifically, it reflects the factors that depend on the different degradation mechanisms of the internal resistance 604 and the polarization resistance 606 (in other words, the factors that depend on the degradation degree of the DC resistance component and the polarization resistance component of the battery pack 101) into the SOHR. The corrected SOHR is used to correct the MidDCR obtained from the intermediate DCR table 608. The corrected SOHR is the aforementioned SOHR for MidDCR. Therefore, in (Equation 6), "SOHR for MidDCR(t) / 100" is equivalent to the correction coefficient of the intermediate DCR (the correction coefficient corresponding to the corrected SOHR of the battery pack 101), and "MidDCR(t)×SOHR for MidDCR(t) / 100" is equivalent to the MidDCR(t) corrected using SOHR for MidDCR(t) (the corrected SOHR(t)).

[0062] SOHR for MidDCR(t) (the modified SOHR(t)) is represented by the following (Equation 10).

[0063] SOHR for MidDCR=h(SOHR) (Formula 10)

[0064] h is an element that depends on the different degradation mechanisms of the internal resistor 604 and the polarization resistor 606. Figure 8 This example illustrates the relationship between h and different battery temperatures.

[0065] According to the inventors' research, the internal resistance 604 and polarization resistance 606 are affected by battery temperature, and SOHR for MidDCR depends linearly on the SOHR calculated by the battery state calculation unit 501 in a manner that varies with battery temperature. Regarding Figure 8 The battery temperatures T1 and T shown are... N The following (Equation 11a) and (Equation 11b) hold true.

[0066] SOHR for MidDCR = λ1 × SOHR + 100, at temperature T1 (Equation 11a)

[0067] SOHR for MidDCR=λ N ×SOHR+100, at temperature T N Time (Equation 11b)

[0068] λ1 (λ1>0) is the slope of the straight line 801 representing the relationship between SOHR at battery temperature T1 and SOHR for MidDCR. N (λ N >0) indicates the battery temperature T N The slope of the straight line 802 relating SOHR to SOHR for MidDCR.

[0069] The element h reflected in the SOHR calculated by the battery state calculation unit 501 is not limited to Figure 8 The example shown. Element h can also be determined based on the analysis results of the test results of battery pack 101 or the simulation results of battery pack 101, etc.

[0070] As long as the interpolated MidOCV(t) and MidDCR(t) can be obtained as described above, the intermediate voltage calculation unit 502 can calculate the intermediate voltage MidVoltage(t) at the current time t by applying these values ​​to Equation 6 as described above.

[0071] The remaining capacity calculation unit 503 calculates the remaining capacity of the battery pack 101 based on the state of charge (SOC) and the decrease in charging capacity (SOHQ) obtained from the battery state calculation unit 501 using the following formula (12).

[0072] RemainingCapacity(t)={(SOC(t)-SOC min ) / 100}×Ah rated ×{SOHQ(t) / 100} (Equation 12)

[0073] In Expression (12), RemainingCapacity(t) represents a value of the remaining capacity at the current time t. Further, Ah rated represents the rated capacity of the battery group 101, that is, the remaining capacity at the time of full charge at the start time point of use of the battery group 101.

[0074] According to the first embodiment of the application described above, the following effects are obtained. (1) The battery management device 102 is a device that manages the battery group 101 that can be charged and discharged, and includes: a battery state calculating section 501 that calculates a state of charge SOC that represents the state of charge of the battery group 101, a charge capacity reduction amount SOHQ that represents the degree of capacity deterioration, and an internal resistance increase amount SOHR that represents the degree of resistance deterioration; an intermediate voltage calculating section 502 that corrects the calculated SOHR, corrects an intermediate resistance (MidDCR(t)) corresponding to the intermediate voltage 710 (MidVoltage(t)) by a correction coefficient (SOHR for MidDCR(t) / 100) corresponding to the corrected degree of resistance deterioration (SOHR for MidDCR(t)), and calculates an intermediate voltage 710 (MidVoltage(t)) existing between a voltage value 704 of the discharge voltage at the current state of charge of the battery group 101 and a voltage value 706 of the discharge voltage at the minimum state of charge SOC min of the battery group 101, according to the corrected intermediate resistance; a remaining capacity calculating section 503 that calculates the remaining capacity (RemainingCapacity(t)) of the battery group 101, according to the state of charge SOC and the charge capacity reduction amount SOHQ; and an available energy calculating section 504 that calculates the available energy of the battery group 101, according to the intermediate voltage and the remaining capacity. Thus, the available energy of the battery group 101 can be accurately estimated (in particular, the available energy can be more accurately estimated than when the available energy of the battery group 101 is calculated according to the SOHR before correction). (2) The intermediate voltage calculating section 502 calculates the intermediate voltage (MidVoltage(t)) according to the open-circuit intermediate voltage MidOCV(t) corresponding to the intermediate voltage and the intermediate drop voltage (for example, "I C0,DCh × MidDCR(t) x SOHR for MidDCR(t) / 100" in Expression (6)) that is the potential difference between both ends of the battery due to the corrected intermediate resistance (for example, "MidDCR(t) x SOHR for MidDCR(t) / 100" in Expression (6)) when the prescribed charge and discharge current flows. Thus, it is expected that the accuracy of the intermediate voltage calculated according to the state of the battery group 101 is high. (3) The corrected resistance degradation (SOHR for MidDCR(t)) depends on both Ro (the resistance value depending on the degradation of the internal resistance 604 of the battery pack 101) and Rp (the resistance value depending on the degradation of the polarization resistance 606 of the battery pack 101). Therefore, compared to the case where only Ro is considered, the accuracy of the calculated usable energy can be expected to be higher. (4) The intermediate voltage calculation unit incorporates the factors h, which depend on both the degradation mechanism of the internal resistance 604 of the battery pack 101 and the degradation mechanism of the polarization resistance 606 of the battery pack 101, into the calculated resistance degradation degree SOHR, thereby correcting the calculated resistance degradation degree SOHR. Therefore, both Ro and Rp are incorporated into the correction of SOHR, thus improving the accuracy of SOHR as a factor in the calculation of usable energy. As a result, high accuracy in the calculated usable energy can be expected. (5) Figure 3 As shown, the intermediate voltage 710 is the value obtained by multiplying the intermediate voltage 710 by the remaining capacity and represents the value from the current state of charge (SOC) to the minimum state of charge (SOC). min The voltage is consistent with the integral value of the discharge curve 701 showing the change in discharge voltage up to this point. The available energy calculation unit 504 calculates the available energy by multiplying the intermediate voltage by the remaining capacity using (Equation 2). Therefore, the available energy of the battery pack 101 can be calculated in real time even when the discharge current changes. (6) The intermediate voltage calculation unit 502 calculates the battery pack 101's state of charge (SOC) and battery temperature (T). cell Each combination is set with a voltage value MidOCV i,j The intermediate OCV table 607 and the state of charge (SOC) of battery pack 101 are related to the battery temperature T. cell Each combination is set with a resistance value MidDCR i,j The intermediate DCR table 608 is used. Therefore, the intermediate OCV table 607 and the intermediate DCR table 608 are used to obtain the state of charge (SOC(t)) calculated by the battery state calculation unit 501 and the current battery temperature T of the battery pack 101, respectively. cell The intermediate voltage MidVoltage(t) is calculated based on the obtained voltage value MidOCV(t) and resistance value MidDCR(t). Therefore, the intermediate voltage corresponding to the state of battery pack 101 can be easily and reliably calculated. (7) The intermediate voltage calculation unit 502 can also obtain the state of charge SOC(t) calculated by the battery state calculation unit 501 and the current battery temperature T of the battery pack 101 from the intermediate OCV table 607 and the intermediate DCR table 608 respectively by interpolation. cell(t) corresponds to the voltage value MidOCV(t) and the resistance value MidDCR(t). Thus, for the state of charge (SOC) and battery temperature (T) not recorded in intermediate OCV table 607 and intermediate DCR table 608... cell The combination can also accurately obtain the corresponding voltage value MidOCV(t) and resistance value MidDCR(t). (Second Implementation)

[0075] Next, the second embodiment of the present invention will be described. In this embodiment, a discharge current I determined taking into account the actual driving conditions of the vehicle equipped with the battery pack 101 is used. Ck,DCh Instead of the fixed discharge current I described in the first embodiment C0,DCh The method for calculating the usable energy of battery pack 101 will be explained. Furthermore, the configuration of the power storage system in this embodiment is the same as that described in the first embodiment. Figure 1 The description is the same as that of the Power Storage System (BESS) 1, so it is omitted.

[0076] In this embodiment, the discharge current I Ck,DCh The value is not the discharge current I in the first embodiment. C0,DCh Instead of a preset value, the battery management device 102 determines the value based on the vehicle's recent driving conditions. That is, the available energy of the battery pack 101 in this embodiment is equivalent to enabling each battery cell of the battery pack 101 to discharge at a current I... Ck,DCh During discharge, the SOC of each battery cell becomes the minimum permissible SOC value for that individual battery cell. min During the specified period, each battery cell can operate at a voltage not lower than the specified minimum voltage V. min The total electrical energy (Wh) released under the condition of [unspecified circumstances].

[0077] Figure 9 This diagram illustrates the functional blocks of the battery management device 102a related to the available energy calculation process according to the second embodiment of the present invention. The battery management device 102 of this embodiment includes functional blocks such as a battery state calculation unit 501, an intermediate voltage calculation unit 502a, a remaining capacity calculation unit 503, an available energy calculation unit 504, and a C-rate calculation unit 505. These functional blocks are implemented, for example, by executing a predetermined program in a computer.

[0078] Figure 9 The battery state calculation unit 501, the remaining capacity calculation unit 503, and the available energy calculation unit 504 are respectively the same as those described in the first embodiment. Figure 4 It is the same as that in the battery management device 102. Therefore, the following mainly refers to the replacement. Figure 2 The intermediate voltage calculation unit 502 is set upFigure 9 The operation of the intermediate voltage calculating section 502a and the newly provided C-rate calculating section 505 will be described, and the description of other functional blocks of the battery state calculating section 501 will be omitted. Figure 9

[0079] The C-rate calculating section 505 calculates the C-rate at the time of discharging of the battery group 101, that is, the ratio of the magnitude of the discharging current to the capacity of the battery group 101. For example, the measured values of the discharging current obtained from a prescribed time ago to the present are averaged, and the average value is divided by the rated capacity of the battery group 101, whereby the C-rate at the time of discharging is calculated. The value of the C-rate calculated by the C-rate calculating section 505 is input to the intermediate voltage calculating section 502a.

[0080] The intermediate voltage calculating section 502a acquires the state-of-charge SOC and the internal resistance increase amount SOHR among the state values of the battery group 101 calculated by the battery state calculating section 501, and also acquires the battery temperature T cell from the temperature sensor 106. Furthermore, the C-rate is acquired from the C-rate calculating section 505. Then, the intermediate voltage 710 described in the first embodiment using Figure 3 is calculated based on these acquired information.

[0081] Figure 10 A diagram showing the functional blocks of the intermediate voltage calculating section 502a of the second embodiment of the present application. The intermediate voltage calculating section 502a is provided with an intermediate OCV table group 610, an intermediate DCR table group 611, an SOHR correction section 1610, and a gain setting section 612.

[0082] The state-of-charge SOC acquired from the battery state calculating section 501, the battery temperature T cell acquired from the temperature sensor 106, and the C-rate acquired from the C-rate calculating section 505 are input to the intermediate OCV table group 610 and the intermediate DCR table group 611, respectively. The intermediate OCV table group 610 and the intermediate DCR table group 611 respectively find the intermediate OCV and the intermediate DCR corresponding to the current state of the battery group 101 by table search based on these input information.

[0083] In the intermediate OCV table group 610, a MidOCV representing the value of the intermediate OCV is set for each combination of the C-rate, the state-of-charge SOC, and the battery temperature T cell . Specifically, a plurality of tables in which the value of the MidOCV is set for each combination of the state-of-charge SOC and the battery temperature T cell are set according to the value of the C-rate. For example, if the value of the C-rate is expressed as C k (k = 1 ~ N), a table in which the value of the MidOCV is set for each C k ​The same table as the intermediate OCV table 607 explained in the first embodiment is set, and the number of the tables is N. The value of MidOCV in each table is set to the value under the corresponding C k rate.

[0084] Similarly, in the intermediate DCR table group 611, for each combination of the C rate, the state of charge SOC, and the battery temperature T cell , a MidDCR indicating the value of the intermediate DCR is set. Specifically, a plurality of tables in which the value of MidDCR is set for each combination of the state of charge SOC and the battery temperature T cell are set according to the value of the C rate. That is, if the value of the C rate is expressed as C k (k = 1 ~ N) as described above, a table in which the value of MidDCR is set for each C k rate is set. The number of the tables is N. The value of MidDCR in each table is set to the value under the corresponding C k rate. The value of MidDCR can be set for both Ro and Rp.

[0085] The intermediate voltage calculating section 502a acquires the values of the intermediate OCV and the intermediate DCR corresponding to the values of the state of charge SOC, the battery temperature T cell , and the C rate of the input current battery group 101 from the intermediate OCV table group 610 and the intermediate DCR table group 611, respectively.

[0086] The gain setting section 612 sets the rated capacity Ah rated of (Formula 12) explained in the first embodiment as the gain for the input C rate. Then, the value of the C rate is multiplied by the rated capacity Ah rated , and thus the discharge current I Ck,DCh is calculated.

[0087] The intermediate voltage calculating section 502a calculates the intermediate voltage explained in the first embodiment by the following (Formula 13) according to the values of the intermediate OCV and the intermediate DCR acquired from the intermediate OCV table group 610 and the intermediate DCR table group 611, the discharge current I Ck,DCh output from the gain setting section 612, and the SOHR for MidDCR (corrected SOHR). Figure 3 Here, if the value of the C rate at the current time t is expressed as C(t), then I Ck,DCh = C(t) x Ah rated .

[0088] MidVoltage(t) = MidOCV(t) - I Ck,DCh x MidDCR(t) x SOHR for MidDCR(t) / 100 (Form 13)

[0089] As with (Form 6) explained in the first embodiment, in (Form 13), MidVoltage(t) represents the value of the intermediate voltage at the current time t. Further, MidOCV(t) and MidDCR(t) respectively represent the values of the intermediate OCV and the intermediate DCR at the current time t, which are respectively acquired from the intermediate OCV table group 610 and the intermediate DCR table group 611. SOHR for MidDCR(t) represents the value of the corrected SOHR at the time t.

[0090] Further, in the present embodiment, as with the first embodiment, MidOCV(t) and MidDCR(t) of (Form 13) can also be acquired from the intermediate OCV table group 610 and the intermediate DCR table group 611 respectively by interpolation with respect to the current state of charge SOC and the battery temperature T cell corresponding to the values of the C rate, the state of charge SOC, and the battery temperature T cell for which the intermediate OCV and the intermediate DCR are to be calculated. Thereby, for a combination of the C rate, the state of charge SOC, and the battery temperature T cell for which the intermediate OCV and the intermediate DCR are not recorded in the intermediate OCV table group 610 and the intermediate DCR table group 611, appropriate voltage values and resistance values can be calculated as the intermediate OCV and the intermediate DCR.

[0091] For example, the values of the state of charge SOC, the battery temperature T cell , and the C rate at the time t are respectively represented as SOC(t), T cell (t), and C(t), and they satisfy the following (Form 14) relationship. In this case, MidOCV(t) and MidDCR(t) corresponding to the combination of SOC(t), T i (t), and C(t) are not recorded in the intermediate OCV table group 610 and the intermediate DCR table group 611.

[0092] T cell (t) < T i+1 SOC j < SOC(t) < SOC j+1 C k < C(t) < C k+1 (Form 14)

[0093] In the above case, the intermediate voltage calculation section 502a first calculates the table corresponding to C k and C k+1 by interpolation using the two tables respectively corresponding to C i,j(C k , k+1 ) MidOCV i+1,j (C k , k+1 ) MidOCV i,j+1 (C k , k+1 ) MidOCV i+1,j+1 (C k , k+1 ) i or T i+1 and SOC j or SOC j+1 , respectively, can be utilized to interpolate MidOCV(t) at time t by the following (Equation 15).

[0094] MidOCV(t) = f(SOC(t), T cell (t), MidOCV i,j (C k , k+1 ) MidOCV i+1,j (C k , k+1 ) MidOCV i,j+1 (C k , k+1 ) MidOCV i+1,j+1 (C k , k+1 ) (Equation 15)

[0095] Further, the intermediate voltage calculation section 502a first interpolates a table corresponding to C(t) using two tables corresponding to C k and C k+1 in the intermediate DCR table set 611. Then, in the calculated table, MidDCR i,j (C k , k+1 ) MidDCR i+1,j (C k , k+1 ) MidDCR i,j+1 (C k , k+1 ) MidDCR i+1,j+1 (C k , k+1 ) are extracted in the form of T i or T i+1 and SOC j or SOC j+1The four resistance values of the four combinations combined can be used to obtain MidDCR(t) at time t by interpolation using the following (Formula 16).

[0096] MidDCR(t) = g(SOC(t), T cell (t), MidDCR i,j (C k , C k+1 ), MidDCR i+1,j (C k , C k+1 ), MidDCR i,j+1 (C k , C k+1 ), MidDCR i+1,j+1 (C k , C k+1 ) (Formula 16)

[0097] As long as MidOCV(t) and MidDCR(t) based on interpolation can be obtained as explained above, the intermediate voltage calculation section 502a can calculate the intermediate voltage MidVoltage(t) at the current time t by applying these values to the above-mentioned (Formula 13).

[0098] According to the second embodiment of the application explained above, in addition to the effects of (1) to (5) explained in the first embodiment, the following effects are also obtained. (8) The battery management device 102 is provided with a C-rate calculation section 505 that calculates the C-rate at the time of discharge of the battery pack 101. The intermediate voltage calculation section 502a uses the C-rate calculated by the C-rate calculation section 505 to calculate the intermediate voltage 710. Therefore, the intermediate voltage 710 can be appropriately calculated taking into account the actual driving state of the vehicle on which the battery pack 101 is mounted. (9) The intermediate voltage calculation section 502a has an intermediate OCV table group 610 in which the intermediate OCV values MidOCV cell are set for each combination of the C-rate, the state of charge SOC, and the battery temperature T i,j of the battery pack 101, and an intermediate DCR table group 611 in which the resistance values MidDCR cell are set for each combination of the C-rate, the state of charge SOC, and the battery temperature T i,j of the battery pack 101. Then, from the intermediate OCV table group 610 and the intermediate DCR table group 611, the value C(t) of the C-rate calculated by the C-rate calculation section 505, the state of charge SOC(t) calculated by the battery state calculation section 501, and the current battery temperature T cell(t) the voltage value MidOCV(t) and the resistance value MidDCR(t) corresponding to the C-rate, the state of charge SOC(t), and the current battery temperature T of the battery group 101. Thus, the intermediate voltage corresponding to the state of the battery group 101 can be easily and reliably calculated. (10) The intermediate voltage calculating section 502a can also acquire the voltage value MidOCV(t) and the resistance value MidDCR(t) corresponding to the value C(t) of the C-rate calculated by the C-rate calculating section 505, the state of charge SOC(t) calculated by the battery state calculating section 501, and the current battery temperature T of the battery group 101 by interpolating from the intermediate OCV table group 610 and the intermediate DCR table group 611. cell (t) the voltage value MidOCV(t) and the resistance value MidDCR(t) corresponding to the C-rate, the state of charge SOC(t), and the current battery temperature T of the battery group 101. Thus, the intermediate voltage corresponding to the state of the battery group 101 can be easily and reliably calculated. cell (t) the voltage value MidOCV(t) and the resistance value MidDCR(t) corresponding to the C-rate, the state of charge SOC(t), and the current battery temperature T of the battery group 101. Thus, the intermediate voltage corresponding to the state of the battery group 101 can be easily and reliably calculated. (3rd Embodiment)

[0099] Next, the 3rd embodiment of the present application will be described. Hereinafter, mainly the points different from the 1st embodiment will be described, and the common points with the 1st embodiment will be omitted or simplified.

[0100] Figure 11 A diagram showing the functional blocks of the battery management device 102b related to the available energy calculating process of the 3rd embodiment of the present application. The battery management device 102b of the present embodiment has a battery state calculating section 501b and an intermediate voltage calculating section 502b instead of the battery state calculating section 501 and the intermediate voltage calculating section 502 shown in the 1st embodiment. These functional blocks are realized, for example, by executing a prescribed program in a computer. Figure 4

[0101] ​The difference between the battery state calculating section 501 and the battery state calculating section 501b is as follows. That is, the battery state calculating section 501b calculates SOHR for Ro and SOHR for Rp instead of SOHR calculated by the battery state calculating section 501. SOHR for Ro is SOHR with respect to Ro, and SOHR for Rp is SOHR with respect to Rp. For example, SOHR for Ro (t) = {Ro (t) / Ro, new} x 100 and SOHR for Rp (t) = {Rp (t) / Rp, new} x 100 can be used. SOHR for Ro (t) is SOHR for Ro at time t, Ro (t) is Ro at time t, and Ro, new is initial Ro. SOHR for Rp (t) is SOHR for Rp at time t, Rp (t) is Rp at time t, and Rp, new is initial Rp.

[0102] The difference between the intermediate voltage calculating section 502 and the intermediate voltage calculating section 502b is as follows. The intermediate voltage calculating section 502b receives SOHR for Ro and SOHR for Rp calculated by the battery state calculating section 501a instead of SOHR.

[0103] Figure 12 A diagram showing a functional block of the intermediate voltage calculating section 502b of the third embodiment of the present application. The intermediate voltage calculating section 502b has a SOHR correction section 1610a instead of the SOHR correction section 1610 shown in FIG. 17. Figure 7

[0104] The difference between the SOHR correction section 1610 and the SOHR correction section 1610a is as follows. The SOHR correction section 1610a receives SOHR for Ro and SOHR for Rp calculated by the battery state calculating section 501a instead of SOHR. The SOHR correction section 1610a calculates SOHR for MidDCR from SOHR for Ro and SOHR for Rp. SOHR for MidDCR can be based on SOHR for Ro and its weight A and SOHR for Rp and its weight B, for example. The weight A and the weight B can be absolute weights or relative weights. For example, SOHR for MidDCR can be a weighted sum of SOHR for Ro and SOHR for Rp as shown in the following (Equation 17).

[0105] SOHR for MidDCR = A x SOHR for Ro + B x SOHR for Rp (Equation 17)

[0106] ​Each of the weights A and B can be a constant or a variable value that varies depending on a parameter such as a battery temperature. The parameter can be determined, for example, based on experimental results of discharges at C rates under various battery deterioration levels.

[0107] According to the second embodiment of the application described above, in addition to the effects of (1) to (7) described in the first embodiment, the following effects are also achieved. (11) The calculated resistance deterioration degree SOHR is a deterioration degree of the internal resistance 604 of the battery pack 101, i.e., an internal resistance deterioration degree SOHR for Ro, and a deterioration degree of the polarization resistance 606 of the battery pack 101, i.e., a polarization resistance deterioration degree SOHR for Rp. The intermediate voltage calculation section 502b calculates a corrected resistance deterioration degree (SOHR for MidDCR) based on the calculated SOHR for Ro, the weight A of SOHR for Ro, the calculated SOHR for Rp, and the weight B of SOHR for Rp. Therefore, both Ro and Rp are reflected in the corrected SOHR, so the accuracy of SOHR as one element of the calculated available energy is improved, and as a result, the accuracy of the calculated available energy is expected to be high.

[0108] Further, in each of the embodiments described above, the application to the use case of the power storage system mounted in an electric vehicle, a hybrid vehicle, or the like is described, but the application can also be similarly applied to a power storage system used for other purposes, such as a power storage system used in connection with a power transmission grid.

[0109] Further, in each of the embodiments described above, the method of calculating the available energy when the battery pack 101 is discharged is described, but the same calculation method can also be applied to the chargeable energy when the battery pack 101 is charged. Here, the chargeable energy is defined as the total amount of electric energy that can be stored when the battery pack 101 is charged from a certain state of charge. This corresponds to the sum of the amounts of electric energy (Wh) that can be charged into each battery cell during a period in which the SOC of each battery cell becomes a maximum SOC value allowed for each battery cell, i.e., SOC max , from the current SOC of the battery pack 101, when each battery cell is charged at a certain charge current.

[0110] In the case of applying the calculation to the chargeable energy, Figure 3 The intermediate voltage 710 described in the above (1) is present on a charge curve that shows a change in the voltage of the battery pack 101 from the current SOC to the SOC max , until the end of charging. maxthe voltage value of the intermediate voltage 710 multiplied by the value defined as the difference between the current SOC and the SOC max the value of the integral of the charge curve from the current SOC to the SOC max The intermediate voltage 710 is found in a manner that the value obtained by multiplying the intermediate voltage 710 by the value defined as the difference between the current SOC and the SOC C0,DCh of the internal resistance is made to coincide with the value of the integral of the charge curve from the current SOC to the SOC Ck,DCh of the internal resistance. Specifically, the intermediate voltage at the time of charging can be found using the same intermediate voltage finding section as the intermediate voltage finding section 502 explained in the first embodiment or the intermediate voltage finding section 502a explained in the second embodiment. In addition, the intermediate voltage at the time of charging (CCV) appears a voltage rise corresponding to the internal resistance compared to the intermediate OCV, so the above-described (Formula 6), (Formula 13) are respectively modified as follows (Formula 6'), (Formula 13') and used.

[0111] MidVoltage(t) = MidOCV(t) + I C0,DCh x MidDCR(t) x SOHR for MidDCR(t) / 100 (Formula 6')

[0112] MidVoltage(t) = MidOCV(t) + I Ck,DCh x MidDCR(t) x SOHR for MidDCR(t) / 100 (Formula 13')

[0113] The chargeable energy can be calculated by multiplying the intermediate voltage at the time of charging thus found by the chargeable capacity found by (Formula 18) below. In (Formula 18), ChargeableCapacity(t) represents the value of the chargeable capacity at the current time t. In addition, Ah rated represents the rated capacity of the battery pack 101, that is, the remaining capacity at the time of full charging at the start time point of use of the battery pack 101.

[0114] ChargeableCapacity(t) = {(SOC max - SOC(t)) / 100} x Ah rated x SOHQ for MidDCR(t) / 100 (Formula 18)

[0115] In addition, the third embodiment can be applied to the second embodiment in addition to the first embodiment. Specifically, for example, the above-described (Formula 6'), (Formula 13') can be used. Figure 2The battery state calculating section 501 in the embodiment is replaced with the battery state calculating section 501b in the third embodiment. Further, the SOHR correcting section 1610 in the second embodiment is replaced with the SOHR correcting section 1610a in the third embodiment. In the case where the third embodiment is reflected in the second embodiment, the above-mentioned effects (11) is achieved in addition to the above-mentioned effects (1) to (5) and (8) to (11).

[0116] The present application can be variously changed without departing from the gist thereof, and is not limited to the above-described embodiments and modified examples. Explanation of symbols

[0117] 1 … Power storage system (BESS) 2 … Inverter 3 … Load 4 … Upper-level controller 101 … Battery pack 102, 102a, 102b … Battery management device 103 … Current sensor 104 … Cell controller 105 … Voltage sensor 106 … Temperature sensor 107 … Relay 501, 501a … Battery state calculating section 502, 502a, 502b … Intermediate voltage calculating section 503 … Residual capacity calculating section 504 … Available energy calculating section 505 … C-rate calculating section 601 … Battery model section 602 … Deterioration state detecting section 603 … Open-circuit voltage source 604 … Internal resistance 605 … Polarization capacitance 606 … Polarization resistance 607 … Intermediate OCV table 608 … Intermediate DCR table 609 … Discharge current setting section 610 … Intermediate OCV table group 611 … Intermediate DCR table group 612 … Gain setting section 1610, 1610a … SOHR correcting section

Claims

1. A battery management device that manages a chargeable and dischargeable battery, characterized by, Possessing: a battery state calculating section that calculates a state of charge, a capacity deterioration degree, and a resistance deterioration degree of the battery; an intermediate voltage calculating section that corrects the calculated resistance deterioration degree, corrects an intermediate resistance of the battery corresponding to an intermediate voltage in accordance with a correction coefficient corresponding to the corrected resistance deterioration degree, and calculates the intermediate voltage from an open-circuit intermediate voltage corresponding to the intermediate voltage and an intermediate voltage drop generated by the corrected intermediate resistance when a prescribed charge-discharge current is flowing through the battery; a remaining capacity calculating section that calculates a remaining capacity or a chargeable capacity of the battery from the state of charge and the capacity deterioration degree; and a usable energy calculating section that calculates a usable energy or a chargeable energy of the battery from the intermediate voltage and the remaining capacity or the intermediate voltage and the chargeable capacity.

2. The battery management device according to claim 1, wherein the intermediate voltage is a voltage that makes a product of the intermediate voltage and the remaining capacity equal to the usable energy or a product of the intermediate voltage and the chargeable capacity equal to the chargeable energy.

3. The battery management device according to claim 1, wherein the corrected resistance deterioration degree depends on both a deterioration degree of an internal resistance of the battery and a deterioration degree of a polarization resistance of the battery.

4. The battery management device according to claim 3, wherein the intermediate voltage calculating section reflects elements depending on both a deterioration mechanism of the internal resistance of the battery and a deterioration mechanism of the polarization resistance of the battery into the calculated resistance deterioration degree, thereby correcting the calculated resistance deterioration degree.

5. The battery management device according to claim 3, wherein the calculated resistance deterioration degree is a deterioration degree of the internal resistance of the battery, i.e., an internal resistance deterioration degree, and a deterioration degree of the polarization resistance of the battery, i.e., a polarization resistance deterioration degree, the intermediate voltage calculating section calculates the corrected resistance deterioration degree from the calculated internal resistance deterioration degree, a weight of the internal resistance deterioration degree, the calculated polarization resistance deterioration degree, and a weight of the polarization resistance deterioration degree.

6. The battery management device according to any one of claims 1 to 5, wherein the intermediate voltage is a voltage that makes a value obtained by multiplying the intermediate voltage by the remaining capacity or the chargeable capacity coincide with an integral value of a charge-discharge curve that indicates a change in the charge-discharge voltage from the current state of charge to the minimum state of charge or the maximum state of charge, the usable energy calculating section calculates the usable energy or the chargeable energy by multiplying the intermediate voltage by the remaining capacity or the chargeable capacity.

7. The battery management device according to any one of claims 1 to 5, wherein the intermediate voltage calculating section has a first table in which voltage values are set for each combination of a state of charge and a temperature of the battery, and a second table in which resistance values are set for each combination of a state of charge and a temperature of the battery, ​ acquiring a voltage value and a resistance value corresponding to the state of charge calculated by the battery state calculating section and the current temperature of the battery from the first table and the second table, respectively, calculating the intermediate voltage from the acquired voltage value and resistance value.

8. The battery management device according to claim 7, wherein the intermediate voltage calculating section acquires a voltage value and a resistance value corresponding to the state of charge calculated by the battery state calculating section and the current temperature of the battery from the first table and the second table, respectively, by interpolation.

9. The battery management device according to any one of claims 1 to 5, wherein a C-rate calculating section that calculates a C-rate at the time of charge and discharge of the battery is provided, the intermediate voltage calculating section calculates the intermediate voltage using the C-rate calculated by the C-rate calculating section.

10. The battery management device according to claim 9, wherein the intermediate voltage calculating section has a first table in which a voltage value is set for each combination of a C-rate, a state of charge, and a temperature of the battery, and a second table in which a resistance value is set for each combination of a C-rate, a state of charge, and a temperature of the battery, a voltage value and a resistance value corresponding to the C-rate calculated by the C-rate calculating section, the state of charge calculated by the battery state calculating section, and the current temperature of the battery are acquired from the first table and the second table, respectively, the intermediate voltage is calculated from the acquired voltage value and resistance value.

11. The battery management device according to claim 10, wherein the intermediate voltage calculating section acquires a voltage value and a resistance value corresponding to the C-rate calculated by the C-rate calculating section, the state of charge calculated by the battery state calculating section, and the current temperature of the battery from the first table and the second table, respectively, by interpolation.

12. A battery management method for managing a chargeable and dischargeable battery, the method characterized by: calculating, by means of a computer, a state of charge, a capacity deterioration degree, and a resistance deterioration degree of the battery, correcting the calculated resistance deterioration degree, correcting an intermediate resistance of the battery corresponding to an intermediate voltage according to a correction coefficient corresponding to the corrected resistance deterioration degree, calculating the intermediate voltage from an open-circuit intermediate voltage corresponding to the intermediate voltage and an intermediate voltage drop due to the corrected intermediate resistance when a prescribed charge and discharge current is flowing, calculating a remaining capacity or a chargeable capacity of the battery from the calculated state of charge and capacity deterioration degree, calculating a usable energy or a chargeable energy of the battery from the calculated intermediate voltage and remaining capacity or the calculated intermediate voltage and chargeable capacity.

13. An electrical power storage system characterized by, providing: the battery management device according to any one of claims 1 to 11; a chargeable and dischargeable battery; and a charge and discharge device that performs charge and discharge of the battery according to the usable energy or chargeable energy of the battery calculated by the battery management device.

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