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

Abstract

The battery management device (102) of the present invention calculates the state of charge SOC, the charge degradation degree SOHQ, and the resistance degradation degree SOHR representing the charge state of a rechargeable and dischargeable battery, corrects the calculated SOHR, corrects the intermediate resistance MidDCR corresponding to the intermediate voltage MidVoltage according to the correction coefficient corresponding to the SOHR for MidDCR (corrected SOHR), calculates MidVoltage (the voltage between the discharge voltage value representing the current charge state of the battery and the discharge voltage value representing the minimum charge state of the battery), calculates the remaining capacity of the battery based on the SOC and SOHQ, and calculates the available energy of the battery based on the intermediate voltage and the remaining capacity.

Description

Technical Field

[0001] The present invention relates to a battery management device, a battery management method and a power storage system. Background Art

[0002] In recent years, driven by concerns about global warming, the use of power generation and transmission systems that utilize renewable energy sources such as sunlight and wind power and stabilize output using battery energy storage systems (BESS) has been expanding. Furthermore, these power storage systems are widely used in transportation systems such as automobiles to address emissions regulations.

[0003] Conventional power storage systems typically include batteries, a cooling system, and a battery management device. The battery is composed of multiple battery cells, the cooling system cools the battery to regulate its temperature, and the battery management device controls the battery's charge and discharge to maintain a safe system.

[0004] In order to optimize vehicle control while maintaining the battery in a safe state in a power storage system installed in electric vehicles or hybrid vehicles, it is necessary to accurately determine the battery status such as the state of charge (SOC), state of degradation (SOH), and maximum allowable power. These battery statuses are determined based on the measured values ​​of current, voltage, temperature, etc. given by sensors. One of the battery statuses used in such power storage systems is available energy. Available energy represents the total amount of electrical energy remaining in the battery, which is equivalent to the electrical energy that can be released by the battery before reaching the allowable usage limit. This available energy is used, for example, to calculate the vehicle's drivable distance until the battery becomes fully discharged (usage limit).

[0005] Regarding the calculation of available battery energy, a technique described in Patent Document 1 is known. Patent Document 1 discloses the following method: obtaining the initial available battery energy, calculating the cumulative battery energy consumed while the vehicle travels the current cumulative distance, calculating the remaining available battery energy based on these values, and calculating the final power consumption based on the current cumulative distance to calculate the vehicle's remaining travelable distance.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: U.S. Patent No. 9,037,327 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] In the method of Patent Document 1, when calculating the cumulative energy consumption of the battery, errors in the voltage and current sensors accumulate, making it difficult to accurately estimate the available energy of the battery, especially when the vehicle has traveled a long distance.

[0011] Technical means to solve the problem

[0012] The battery management device of the present invention manages a rechargeable and dischargeable battery and comprises: a battery state calculation unit, which calculates the charge state, capacity degradation degree, and resistance degradation degree of the battery; an intermediate voltage calculation unit, which corrects the calculated resistance degradation degree, corrects the intermediate resistance of the battery corresponding to the intermediate voltage according to a correction coefficient corresponding to the corrected resistance degradation degree, and calculates an intermediate voltage between the charge and discharge voltage in the current charge state of the battery and the charge and discharge voltage in the minimum charge state or the maximum charge state of the battery based on the corrected intermediate resistance; a remaining capacity calculation unit, which calculates the remaining capacity or rechargeable capacity of the battery based on the charge state and the capacity degradation degree; and an available energy calculation unit, which calculates the available energy or rechargeable energy of the battery based on the intermediate voltage and the remaining capacity, or the intermediate voltage and the rechargeable capacity.

[0013] The battery management method of the present invention is a method for managing a rechargeable and dischargeable battery, which uses a computer to calculate the battery's state of charge, capacity degradation, and resistance degradation, corrects the calculated resistance degradation, and corrects the battery's intermediate resistance corresponding to the intermediate voltage according to a correction coefficient corresponding to the corrected resistance degradation. Based on the corrected intermediate resistance, the intermediate voltage between the charge and discharge voltage in the battery's current state of charge and the charge and discharge voltage in the battery's minimum state of charge or maximum state of charge is calculated. Based on the calculated state of charge and capacity degradation, the remaining capacity or rechargeable capacity of the battery is calculated. Based on the calculated intermediate voltage and remaining capacity or the calculated intermediate voltage and rechargeable capacity, the available energy or rechargeable energy of the battery is calculated.

[0014] The power storage system of the present invention includes a battery management device, a rechargeable battery, and a charge / discharge device that charges and discharges the battery based on available energy or chargeable energy of the battery calculated by the battery management device.

[0015] Effects of the Invention

[0016] According to the present invention, the available energy of a battery can be accurately inferred. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1This is a schematic diagram of the configuration of a power storage system according to one embodiment of the present invention.

[0018] Figure 2 A diagram illustrating available energy.

[0019] Figure 3 This is a conceptual diagram of a method for calculating available energy according to one embodiment of the present invention.

[0020] Figure 4 This is a diagram showing functional blocks of a battery management device related to available energy calculation processing according to the first embodiment of the present invention.

[0021] Figure 5 This is a diagram showing the functional blocks of the battery state calculation unit.

[0022] Figure 6 A diagram showing an example of an equivalent circuit of a battery cell in a battery model.

[0023] Figure 7 This is a diagram showing the functional blocks of the intermediate voltage calculation unit according to the first embodiment of the present invention.

[0024] Figure 8 An example of h (a factor reflected in SOHR) associated with each battery temperature is shown.

[0025] Figure 9 This is a diagram showing functional blocks of a battery management device related to available energy calculation processing according to a second embodiment of the present invention.

[0026] Figure 10 This is a diagram showing functional blocks of an intermediate voltage calculation unit according to a second embodiment of the present invention.

[0027] Figure 11 This is a diagram showing functional blocks of a battery management device related to available energy calculation processing according to a third embodiment of the present invention.

[0028] Figure 12 This is a diagram showing functional blocks of an intermediate voltage calculation unit according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0029] Next, embodiments of the present invention will be described.

[0030] (First embodiment)

[0031] Figure 1 This is a schematic diagram of the configuration of a power storage system according to one embodiment of the present invention. Figure 1The illustrated power storage system (BESS) 1 includes a battery pack 101, a battery management unit 102, a current sensor 103, a cell 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 an inverter 2. The power storage system 1 and the inverter 2 are connected to a host controller 4 via a communication line (not shown).

[0032] The battery pack 101 is composed of multiple rechargeable and dischargeable battery cells connected in series and parallel. During traction operation of the load 3, the DC power discharged from the battery pack 101 is converted by the converter 2 into AC power and supplied to the load 3. Furthermore, during regenerative operation of the load 3, the AC power output from the load 3 is converted by the converter 2 into DC power and charged into the battery pack 101. The operation of the converter 2 in this manner enables the charging and discharging of the battery pack 101. The operation of the converter 2 is controlled by the host controller 4.

[0033] The current sensor 103 detects the current flowing through the battery pack 101 and outputs the detection result to the battery management device 102. The cell controller 104 detects the voltage of each battery cell in the battery pack 101 and outputs the detection result to the battery management device 102. The voltage sensor 105 detects the voltage (total voltage) of the battery pack 101 and outputs the detection result to the battery management device 102. The temperature sensor 106 detects the temperature of the battery pack 101 and outputs the detection result to the battery management device 102. The relay 107 switches the connection state between the power storage system 1 and the converter 2 under the control of the host controller 4.

[0034] The battery management device 102 controls the charge and discharge of the battery pack 101 based on the detection results 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 various battery states as indicators representing the state of the battery pack 101. Examples of the battery states calculated by the battery management device 102 include the state of charge (SOC) (specifically, the battery's charge rate), the state of degradation (SOH) (specifically, the degree of battery degradation), the maximum allowable power, and the available energy. By using these battery states to control the charge and discharge of the battery pack 101, the battery management device 102 can safely control the battery pack 101. As a result, the host system (electric vehicle, hybrid vehicle, etc.) equipped with the power storage system 1 can be efficiently controlled. The battery management device 102 communicates the information necessary for controlling the charge and discharge of the battery pack 101 with the host controller 4.

[0035] Furthermore, in this embodiment, the so-called available energy is defined as the total amount of electric energy that can be released by the battery pack 101 from the electric energy stored in the battery pack 101. This is equivalent to discharging each battery cell of the battery pack 101 at a certain discharge current I C0,DCh During discharge, the SOC of each battery cell becomes the minimum SOC value allowed for each battery cell, that is, SOC min During the period up to min The total amount of electricity (Wh) released under the condition of . C0,DCh It is set in advance according to the operation mode of the power storage system 1 and the like.

[0036] Figure 2 A diagram illustrating available energy. Figure 2 In the figure, the dashed line indicated by reference numeral 700 represents an SOC-OCV curve, which shows the relationship between the SOC and the open circuit voltage (OCV) of each battery cell of the battery pack 101. In addition, the solid line indicated by reference numeral 701 shows that each battery cell of the battery pack 101 is discharged at a fixed current I C0,DCh Discharge from current SOC to SOC min The discharge curve at the end. Figure 2 The dashed line 703 represents the current SOC, and the dashed line 705 represents the SOC min .

[0037] The discharge curve 701 shows the relationship between the SOC and the closed circuit voltage (CCV) of each battery cell of the battery pack 101 during discharge. That is, the CCV of each battery cell during discharge of the battery pack 101 is set to not fall below the minimum voltage V shown by the dotted line 707 according to the discharge curve 701. min The voltage value 704 corresponding to the current SOC continuously changes to the SOC at the end of discharge. min The corresponding voltage value is 706.

[0038] Here, if the C rate during discharge corresponding to the discharge curve 701 is represented as C0, the discharge current I C0,DCh It can be expressed as I C0,DCh =C0×Ah rated In this formula, Ah rated Indicates the rated capacity of each battery cell.

[0039] In addition, the available energy of each battery cell during discharge is defined by the following (Equation 1).

[0040] [Formula 1]

[0041]

[0042] In (Equation 1), CCV(t) represents the CCV of each battery cell at time t, that is, the value of the discharge voltage. present represents the current time, t end Indicates that the SOC of each battery reaches SOC min The moment when the discharge ends. This (Formula 1) represents Figure 2 From the current SOC to SOC min The integral value of the discharge curve 701 up to . That is, Figure 2 The area of ​​the hatched region 702 surrounded by the discharge curve 701 , the dotted line 703 , and the dotted line 705 corresponds to the available energy of each battery cell.

[0043] For example, when the power storage system 1 is mounted on a vehicle, the available energy of the battery pack 101 must be calculated in real time to achieve appropriate and safe vehicle control. However, the current gradually changes during vehicle operation, so a fixed discharge current I cannot be used. C0,DCh Therefore, in one embodiment of the present invention, the available energy of the battery pack 101 can be directly calculated in real time without using (Formula 1) by using the calculation method described below.

[0044] 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 figure, the SOC-OCV curve 700 and the discharge curve 701 are Figure 2 The corresponding ones are respectively. Figure 3 In addition to these curves, a hatched area 708 is also shown. The area 708 is defined as the following rectangular area: the remaining capacity of each battery cell, that is, the current SOC and the SOC min The difference ΔSOC is the long side, which exists on the discharge curve 701 between the voltage value 704 corresponding to the current SOC and the SOC corresponding to the end of discharge. min The middle voltage 710 between the voltage values ​​706 is the short side.

[0045] In one embodiment of the present invention, Figure 3 The area of ​​region 708 is Figure 2 The intermediate voltage 710 existing on the discharge curve 701 is obtained so that the area of ​​the region 702 is consistent. In this way, the area of ​​the rectangular region 708 can be calculated by multiplying the intermediate voltage 710 by the remaining capacity (ΔSOC). Figure 2 The area of ​​region 702 is the available energy.

[0046] Furthermore, Figure 3In the SOC-OCV curve 700, point 709 represents the OCV value (intermediate OCV) corresponding to the intermediate voltage 710. The intermediate OCV value at the current SOC is the same as the SOC value. min In addition, the point 711 on the horizontal axis represents the SOC value (intermediate SOC) corresponding to the intermediate voltage 710 and the intermediate OCV. The intermediate SOC is between the current SOC and the SOC min between.

[0047] Furthermore, while the above description describes a method for calculating available energy per battery cell, in this embodiment, it is preferred to calculate available energy for the entire battery pack 101. For example, available energy can be calculated for each battery cell comprising the battery pack 101, and the available energy calculation results for each battery cell can be aggregated to determine the available energy for the entire battery pack 101. Alternatively, the available energy can be calculated for the entire battery pack 101 by applying the above calculation method to the entire battery pack 101.

[0048] Next, a method for calculating the available energy according to the present embodiment, which embodies the above-mentioned concept, will be described.

[0049] Figure 4 This diagram illustrates the functional blocks of the battery management device 102 related to the available energy calculation process in the first embodiment of the present invention. The battery management device 102 in this embodiment includes functional blocks: 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 on a computer.

[0050] The battery state calculation unit 501 obtains the current I, closed circuit voltage CCV and battery temperature T detected during the charge and discharge of the battery pack 101 from the current sensor 103, the voltage sensor 105 and the temperature sensor 106 respectively. cell Then, based on this information, the open circuit voltage OCV, state of charge SOC, polarization voltage Vp, charge capacity reduction SOHQ (specifically, for example, the capacity degradation rate (for example, an example of degradation degree)) and internal resistance increase SOHR (specifically, for example, the internal resistance increase rate, in other words, the internal resistance degradation rate (an example of degradation degree)) representing the current state of the battery pack 101 are calculated. The details of the calculation method of these state values ​​by the battery state calculation unit 501 will be referred to later. Figure 5 To explain.

[0051] The intermediate voltage calculation unit 502 obtains the state of charge SOC and the internal resistance increase SOHR of the battery pack 101 calculated by the battery state calculation unit 501, and obtains the battery temperature T from the temperature sensor 106. cell Then, based on the information obtained, we can calculate Figure 3 The intermediate voltage 710 described above. The details of the method for calculating the intermediate voltage by the intermediate voltage calculation unit 502 will be referred to later. Figure 7 To explain.

[0052] The remaining capacity calculation unit 503 obtains the state of charge (SOC) and charge capacity reduction (SOHQ) from the various state values ​​of the battery pack 101 calculated by the battery state calculation unit 501. Based on this information, the remaining capacity of the battery pack 101 at the current time is calculated. Details of the remaining capacity calculation method used by the remaining capacity calculation unit 503 will be described later.

[0053] The available energy calculation unit 504 calculates the available energy of the battery pack 101 based on the intermediate voltage calculated by the intermediate voltage calculation unit 502 and the remaining capacity calculated by the remaining capacity calculation unit 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 (Equation 2).

[0054] Available energy (Wh) = intermediate voltage (V) × remaining capacity (Ah) (Formula 2)

[0055] 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 host controller 4 and used for controlling the converter 2, etc. Thus, the available energy of the battery pack 101 is calculated in real time in the power storage system 1 to control the charge and discharge of the battery pack 101.

[0056] Figure 5 1 is a diagram showing functional blocks of the battery state calculation unit 501. The battery state calculation unit 501 includes a battery model unit 601 and a degradation state detection unit 602.

[0057] The battery model unit 601 stores a battery model obtained by modeling the battery pack 101. This battery model is used to calculate the open circuit voltage OCV, the state of charge SOC, and the polarization voltage Vp. The battery model in the battery model unit 601 is set based on, for example, the number of battery cells in series and parallel in the actual battery pack 101 and the equivalent circuit of each battery cell. The battery model unit 601 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. cellBy applying this battery model, the open circuit voltage OCV, the state of charge SOC, and the polarization voltage Vp according to the state of the battery pack 101 can be obtained.

[0058] Figure 6 This is a diagram showing an example of an equivalent circuit of a battery cell in the battery model set in the battery model unit 601 . Figure 6 The equivalent circuit of the battery cell shown is composed of a no-load voltage source 603, an internal resistor 604, and a polarization model connected in series. The no-load 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 no-load voltage source 603, that is, the voltage value Voc, is equivalent to the open-circuit voltage OCV, and the voltage across the parallel circuit of the polarization capacitor 605 and the polarization resistor 606 is equivalent to the polarization voltage Vp. In addition, the value obtained by adding the applied voltage I×Ro of the internal resistor 604 and the polarization voltage Vp to the open-circuit voltage OCV when a current I flows through the equivalent circuit 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 unit 601, the current I, the closed circuit voltage CCV and the battery temperature T can be used based on these relationships. cell The open circuit voltage OCV and the polarization voltage Vp of the entire battery pack 101 are calculated, and the state of charge SOC is calculated using the calculation result of the open circuit voltage OCV.

[0059] return Figure 5 As described above, the degradation state detection unit 602 detects the degradation state of the battery pack 101 and calculates the charge capacity reduction SOHQ and internal resistance increase SOHR corresponding to the degradation state. Each battery cell of the battery pack 101 degrades due to repeated charge and discharge, and the charge capacity decreases and the internal resistance increases according to the degradation state. The degradation state detection unit 602, for example, pre-stores information indicating the relationship between the current, voltage, and temperature of the battery pack 101 and the degradation state. By using this information, the current I, closed-circuit voltage CCV, and battery temperature T obtained from the current sensor 103, the voltage sensor 105, and the temperature sensor 106, respectively, are used to determine the degradation state. cell The degradation state of the battery pack 101 is detected. Then, based on the pre-stored relationship between the degradation state, the charge capacity decrease SOHQ, and the internal resistance increase SOHR, the charge capacity decrease SOHQ and the internal resistance increase SOHR corresponding to the detection result of the degradation state of the battery pack 101 can be obtained.

[0060] As described above, the internal resistance increases depending on the deterioration state of the battery pack 101. When the initial internal resistance value is expressed as Ro,new and the internal resistance value at the current time t is expressed as Ro(t), the internal resistance increase SOHR(t) at the current time t is expressed by the following equation (3).

[0061] SOHR(t)={Ro(t) / Ro,new}×100 (Formula 3)

[0062] Figure 7 1 is a diagram showing functional blocks of the intermediate voltage calculation unit 502 according to the first embodiment of the present invention. The intermediate voltage calculation unit 502 includes an intermediate OCV table 607 , an intermediate DCR table 608 , a discharge current setting unit 609 , and a SOHR correction unit 1610 .

[0063] The state of charge SOC obtained from the battery state calculation unit 501 and the battery temperature T obtained from the temperature sensor 106 are used to calculate the battery state SOC. cell The intermediate OCV table 607 and intermediate DCR table 608 respectively input this information. Based on this input information, the intermediate OCV table 607 and intermediate DCR table 608 respectively calculate the intermediate OCV and intermediate DCR corresponding to the current state of the battery pack 101 by searching the tables. The intermediate DCR is the DC resistance value of the battery pack 101 corresponding to the intermediate voltage.

[0064] In the intermediate OCV table 607, the state of charge SOC and the battery temperature T cell For each combination of , MidOCV is set to represent the value of the middle OCV. For example, if the battery temperature T cell The value is expressed as T i (i=1~p), the value of the state of charge SOC is expressed as SOC j (j=1 to q), then p×q voltage values ​​MidOCV represented by the following (Formula 4) are set in the intermediate OCV table 607 for each combination thereof. i,j (V).

[0065] MidOCV i,j =MidOCV(T i ,SOC j ) (Formula 4)

[0066] In the intermediate DCR table 608, the state of charge SOC and the battery temperature T cell For each combination of , MidDCR is set to represent the value of the middle DCR. For example, if the battery temperature T cell The value is expressed as T i (i=1~p), the value of the state of charge SOC is expressed as SOC j(j=1 to q), then p×q resistance values ​​MidDCR expressed by the following (Equation 5) are set in the intermediate DCR table 608 for each combination thereof. i,j (Ω).

[0067] MidDCR i,j =MidDCR(T i ,SOC j ) (Formula 5)

[0068] In addition, 1≤i≤p and 1≤j≤q. MidOCV in the intermediate OCV table 607 i,j The values ​​of and MidDCR in the middle DCR table 608 i,j The values ​​of can be preset based on the analysis results of the discharge test results of the battery pack 101 or the simulation results using the equivalent circuit model of the battery pack 101. For example, these preset values ​​can be written to a memory (not shown) possessed by the battery management device 102, thereby forming the intermediate OCV table 607 and the intermediate DCR table 608 in the battery management device 102. In addition, a discharge experiment at a C rate can be performed during the design phase of the power storage system, and the voltage value MidOCV can be obtained based on the current value, voltage value, and battery temperature obtained from the current sensor 103, voltage sensor 105, and temperature sensor 106, respectively, in the experiment. i,j and resistance value MidDCR i,j Although not shown, the intermediate DCR table 608 may have resistance values ​​MidDCR for both Ro and Rp. i,j .

[0069] The intermediate voltage calculation unit 502 obtains the voltage values ​​MidOCV shown in the above (Formula 4) and (Formula 5) from the intermediate OCV table 607 and the intermediate DCR table 608, respectively. i,j and resistance value MidDCR i,j The current state of charge SOC of the battery pack 101 and the battery temperature T cell Then, according to the obtained values ​​and the discharge current I preset in the discharge current setting unit 609, C0,DCh , and SOHR for MidDCR (corrected SOHR) input from the SOHR correction unit 1610 are calculated by the following (Equation 6): Figure 3 The intermediate voltage described in .

[0070] MidVoltage(t)=MidOCV(t)-I C0,DCh ×MidDCR(t)×SOHR for MidDCR(t) / 100

[0071] (Formula 6)

[0072] In (Equation 6), MidVoltage(t) represents the value of the intermediate voltage at the current moment t. In addition, MidOCV(t) and MidDCR(t) represent the values ​​of the intermediate OCV and intermediate DCR at the current moment t, respectively, which are obtained 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 SOHR calculated by the battery state calculation unit 501 at the moment t after being corrected by the SOHR correction unit 1610, and represents the corrected SOHR value for the intermediate DCR (MidDCR). An example of the open circuit intermediate voltage at the current moment t (the open circuit intermediate voltage corresponding to the intermediate voltage) is MidOCV(t). An example of the intermediate drop voltage at the current moment t (the potential difference between the two ends of the battery caused by the intermediate DCR when the specified charge and discharge current flows) is "I C0,DCh ×MidDCR(t)×SOHR for MidDCR(t) / 100". The SOHR correction unit 1610 will be described later.

[0073] In addition, MidOCV(t) and MidDCR(t) in (Equation 6) are related to the current state of charge SOC and battery temperature T cell The corresponding intermediate OCV and intermediate DCR values ​​can also be obtained from the intermediate OCV table 607 and the intermediate DCR table 608 respectively by interpolation. For example, interpolation can be performed using various well-known interpolation methods such as linear interpolation, Lagrange interpolation, and nearest neighbor interpolation. In this way, the state of charge SOC and battery temperature T that are not recorded in the intermediate OCV table 607 and the intermediate DCR table 608 can be obtained. cell The appropriate voltage and resistance values ​​can be obtained as the intermediate OCV and intermediate DCR by the combination of .

[0074] For example, the state of charge SOC and battery temperature T at time t cell The values ​​are expressed as SOC(t), T cell (t), and they respectively satisfy the following relationship (Equation 7). In this case, corresponding to SOC (t) and T cell The MidOCV(t) and MidDCR(t) of the combination of (t) are not recorded in the intermediate OCV table 607 and the intermediate DCR table 608.

[0075] T i <T cell (t)<T i+1

[0076] SOC j <SOC(t)<SOC j+1 (Equation 7)

[0077] In the above case, the intermediate voltage calculation unit 502 can use the intermediate OCV table 607 corresponding to the T i or T i+1 With SOC j or SOC j+1 The four voltage values ​​of the four combinations are MidOCV i,j 、MidOCV i+1,j 、MidOCV i,j+1 and MidOCV i+1,j+1 MidOCV(t) at time t is obtained by interpolation using the following (Equation 8).

[0078] MidOCV(t)=f(SOC(t),T cell (t),MidOCV i,j ,MidOCV i+1,j ,MidOCV i,j+1 ,MidOCV i+1,j+1 )

[0079] (Equation 8)

[0080] In addition, the intermediate voltage calculation unit 502 can use the intermediate DCR table 608 to calculate the voltages corresponding to the T i or T i+1 With SOC j or SOC j+1 The four resistance values ​​of the four combinations are MidDCR i,j 、MidDCR i+1,j 、MidDCR i,j+1 and MidDCR i+1,j+1 MidDCR(t) at time t is obtained by interpolation using the following (Equation 9).

[0081] MidDCR(t)=g(SOC(t),T cell (t),MidDCR i,j ,MidDCR i+1,j ,MidDCR i,j+1 ,MidDCR i+1,j+1 )

[0082] (Equation 9)

[0083] In the above (Equation 8) and (Equation 9), f and g represent interpolation processing respectively performed on the intermediate OCV table 607 and the intermediate DCR table 608. The content of these processing differs depending on the interpolation method used during interpolation.

[0084] The SOHR correction unit 1610 is 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 made intensive research on the practical application of a battery management device that can calculate the available energy of the battery pack 101 in real time, and have obtained the following findings. That is, Figure 6 As shown, the equivalent circuit of the battery cell has two 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 of these resistors degrade due to repeated charging and discharging of the battery pack 101 and at least one surrounding condition. In addition, the degradation mechanism of the internal resistor 604 with a resistance value Ro and the degradation mechanism of the polarization resistor 606 with a resistance value Rp are not exactly the same (for example, they differ depending on the characteristics of the battery cell (for example, depending on the material used in the battery cell)). SOHR depends not only on Ro but also on Rp. Therefore, the SOHR that complies with (Equation 3) may not necessarily be a sufficiently accurate value for calculating the intermediate DCR (MidDCR) after resistance degradation has occurred. 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 factors that depend on the different degradation mechanisms of the internal resistance 604 and the polarization resistance 606 (in other words, factors that depend on the degree of degradation of the DC resistance component of the battery pack 101 and the degree of degradation of the polarization resistance component of the battery pack 101) in the SOHR. The corrected SOHR is used to correct the MidDCR obtained from the mid-DCR table 608. The corrected SOHR is the aforementioned SOHR for MidDCR. Therefore, in (Equation 6), "SOHR for MidDCR(t) / 100" corresponds to the correction factor for the mid-DCR (the correction factor corresponding to the corrected SOHR of the battery pack 101), and "MidDCR(t) × SOHR for MidDCR(t) / 100" corresponds to the MidDCR(t) corrected using the SOHR for MidDCR(t) (corrected SOHR(t)).

[0085] SOHR for MidDCR(t) (corrected SOHR(t)) is expressed by the following (Equation 10).

[0086] SOHR for MidDCR=h(SOHR) (Formula 10)

[0087] h is a factor that depends on the different degradation mechanisms of the internal resistance 604 and the polarization resistance 606 . Figure 8 An example showing h associated with different battery temperatures.

[0088] According to the research of the inventors of this application, the internal resistance 604 and the polarization resistance 606 are affected by the battery temperature, and the SOHR for MidDCR linearly depends on the SOHR calculated by the battery state calculation unit 501 in a manner different according to the battery temperature. Figure 8 The battery temperature T1 and T N , the following (Formula 11a) and (Formula 11b) hold.

[0089] SOHR for MidDCR = λ1 × SOHR + 100, at temperature T1 (Equation 11a)

[0090] SOHR for MidDCR=λ N ×SOHR+100, at temperature T N Time (Formula 11b)

[0091] λ1 (λ1>0) is the slope of the straight line 801 showing the relationship between SOHR and SOHR for MidDCR at the battery temperature T1. N (λ N >0) indicates the battery temperature T N The slope of straight line 802 showing the relationship between SOHR for ΔH and SOHR for MidDCR.

[0092] The element h reflected in the SOHR calculated by the battery state calculation unit 501 is not limited to Figure 8 The factor h may also be determined based on analysis results of test results of the battery pack 101 or simulation results of the battery pack 101.

[0093] Once the interpolated MidOCV(t) and MidDCR(t) are 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 the aforementioned (Equation 6).

[0094] The remaining capacity calculation unit 503 calculates the remaining capacity of the battery pack 101 using the following (Equation 12) based on the state of charge SOC and the charge capacity reduction SOHQ acquired from the battery state calculation unit 501 .

[0095] RemainingCapacity(t)={(SOC(t)-SOC min ) / 100}×Ah rated ×{SOHQ(t) / 100}

[0096] (Equation 12)

[0097] In (Equation 12), RemainingCapacity(t) represents the value of the remaining capacity at the current time t. rated The rated capacity of the battery pack 101 , that is, the remaining capacity when the battery pack 101 is fully charged at the start of use.

[0098] According to the first embodiment of the present invention described above, the following effects are achieved.

[0099] (1) The battery management device 102 is a device for managing a battery pack 101 that can be charged and discharged, and includes: a battery state calculation unit 501 that calculates a state of charge SOC indicating the state of charge of the battery pack 101, a charge capacity decrease SOHQ indicating a degree of capacity degradation, and an internal resistance increase SOHR indicating a degree of resistance degradation; an intermediate voltage calculation unit 502 that corrects the calculated SOHR, corrects an intermediate resistance (MidDCR(t)) corresponding to an intermediate voltage 710 (MidVoltage(t)) by a correction coefficient (SOHR for MidDCR(t) / 100) corresponding to the corrected degree of resistance degradation (SOHR for MidDCR(t)), and calculates a voltage value 704 of a discharge voltage existing in the current state of charge of the battery pack 101 and a minimum state of charge SOC indicating the battery pack 101 based on the corrected intermediate resistance. min The remaining capacity calculation unit 503 calculates the remaining capacity (RemainingCapacity(t)) of the battery pack 101 based on the state of charge (SOC) and the charge capacity reduction (SOHQ); and the available energy calculation unit 504 calculates the available energy of the battery pack 101 based on the intermediate voltage and the remaining capacity. Therefore, the available energy of the battery pack 101 can be accurately estimated (especially more accurately than when the available energy of the battery pack 101 is calculated based on the SOHR before correction).

[0100] (2) The intermediate voltage calculation unit 502 calculates the intermediate voltage MidOCV(t) corresponding to the intermediate voltage and the intermediate resistance (e.g., "MidDCR(t)×SOHR for MidDCR(t) / 100" in (Equation 6)) which is the potential difference between the two ends of the battery caused by the corrected intermediate resistance when the specified charge / discharge current flows, that is, the intermediate drop voltage (e.g., "I C0,DCh × MidDCR(t) × SOHR for MidDCR(t) / 100″) to calculate the intermediate voltage (MidVoldtage(t)). Therefore, it can be expected that the intermediate voltage calculated based on the state of the battery pack 101 has high accuracy.

[0101] (3) The corrected resistance degradation degree (SOHR for MidDCR(t)) depends on both Ro (a resistance value that depends on the degree of degradation of the internal resistance 604 of the battery pack 101) and Rp (a resistance value that depends on the degree of degradation of the polarization resistance 606 of the battery pack 101). Therefore, compared to a case where only Ro of Ro and Rp is considered, the calculated usable energy can be expected to be more accurate.

[0102] (4) The intermediate voltage calculation unit reflects the factor h, which depends 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, in the calculated resistance degradation degree SOHR, thereby correcting the calculated resistance degradation degree SOHR. Therefore, both Ro and Rp are reflected in the correction of SOHR, thereby improving the accuracy of SOHR, which is a factor in the calculation of available energy. As a result, it can be expected that the accuracy of the calculated available energy will be high.

[0103] (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 at which the integrated value of the discharge curve 701 showing the change in discharge voltage until the discharge current reaches the specified value matches the value obtained by the user. The available energy calculation unit 504 calculates the available energy by multiplying the intermediate voltage by the remaining capacity using Equation 2. Therefore, even when the discharge current varies, the available energy of the battery pack 101 can be calculated in real time.

[0104] (6) The intermediate voltage calculation unit 502 has a charge state SOC and a battery temperature T of the battery pack 101. cell Each combination has a voltage value MidOCV i,j The intermediate OCV table 607 and the state of charge SOC of the battery pack 101 and the battery temperature T cell Each combination has a resistance value MidDCR i,j Then, 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 are obtained from the intermediate OCV table 607 and the intermediate DCR table 608. cell The intermediate voltage MidVoltage(t) is calculated based on the voltage value MidOCV(t) and resistance value MidDCR(t) corresponding to the state of the battery pack 101. Therefore, the intermediate voltage corresponding to the state of the battery pack 101 can be easily and reliably calculated.

[0105] (7) The intermediate voltage calculation unit 502 may 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 by interpolation. cell (t) corresponds to the voltage value MidOCV(t) and the resistance value MidDCR(t). In this way, for the state of charge SOC and battery temperature T not recorded in the intermediate OCV table 607 and the intermediate DCR table 608, cell The combination of can also obtain the corresponding voltage value MidOCV(t) and resistance value MidDCR(t) in detail.

[0106] (Second embodiment)

[0107] Next, a second embodiment of the present invention will be described. In this embodiment, a discharge current I is determined by taking into account the actual driving state of a vehicle equipped with the battery pack 101. Ck,DCh Instead of the fixed discharge current I described in the first embodiment C0,DCh The method of calculating the available energy of the battery pack 101 will be described. Figure 1 Since the battery is the same as the battery storage system (BESS) 1, the description thereof will be omitted.

[0108] In this embodiment, the discharge current I Ck,DCh The value of the discharge current I is not the same as that in the first embodiment. C0,DCh The available energy of the battery pack 101 in this embodiment is equivalent to the energy of each battery cell of the battery pack 101 being discharged at a current I Ck,DCh During discharge, the SOC of each battery cell becomes the minimum SOC value allowed for each battery cell, that is, SOC min During the period up to min The total amount of electricity (Wh) released when

[0109] Figure 9 This diagram illustrates the functional blocks of the battery management device 102a related to the available energy calculation process in the second embodiment of the present invention. The battery management device 102 of this embodiment includes functional blocks: 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 on a computer.

[0110] Figure 9The 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 Therefore, the following is mainly to replace Figure 2 The intermediate voltage calculation unit 502 is provided Figure 9 The operation of the intermediate voltage calculation unit 502a and the newly provided C rate calculation unit 505 will be described and omitted. Figure 9 Description of other function blocks.

[0111] The C-rate calculation unit 505 calculates the C-rate of the battery pack 101 during discharge, that is, the ratio of the discharge current to the capacity of the battery pack 101. For example, the C-rate during discharge is calculated by averaging the discharge current measurements obtained from a predetermined time in the past until the present time and dividing the average by the rated capacity of the battery pack 101. The C-rate value calculated by the C-rate calculation unit 505 is input to the intermediate voltage calculation unit 502a.

[0112] The intermediate voltage calculation unit 502a obtains the state of charge SOC and the internal resistance increase SOHR of the battery pack 101 calculated by the battery state calculation unit 501, and obtains the battery temperature T from the temperature sensor 106. cell Furthermore, the C rate is obtained from the C rate calculation unit 505. Then, the C rate is calculated based on the obtained information. Figure 3 The intermediate voltage 710 described above.

[0113] Figure 10 1 is a diagram showing functional blocks of the intermediate voltage calculation unit 502 a according to the second embodiment of the present invention. The intermediate voltage calculation unit 502 a includes an intermediate OCV table group 610 , an intermediate DCR table group 611 , a SOHR correction unit 1610 , and a gain setting unit 612 .

[0114] The state of charge SOC obtained from the battery state calculation unit 501 and the battery temperature T obtained from the temperature sensor 106 are used. cell , and the C-rate obtained from the C-rate calculation unit 505 are input to the intermediate OCV table group 610 and the intermediate DCR table group 611. Based on this input information, the intermediate OCV table group 610 and the intermediate DCR table group 611 respectively determine the intermediate OCV and intermediate DCR corresponding to the current state of the battery pack 101 by table search.

[0115] In the intermediate OCV table group 610, the C rate, the state of charge SOC and the battery temperature T cell For each combination of , a MidOCV indicating the value of the middle OCV is set. Specifically, a plurality of values ​​for the state of charge SOC and the battery temperature T are set according to the value of the C rate.cell For example, if the value of C rate is expressed as C k (k=1~N), then for each C k The same table as the intermediate OCV table 607 described in the first embodiment is set, and the total number of the tables is N. The value of MidOCV in each table is set to the corresponding C k The value below.

[0116] Similarly, in the intermediate DCR table group 611, the C rate, the state of charge SOC and the battery temperature T cell For each combination of , a MidDCR indicating the value of the middle DCR is set. Specifically, a plurality of values ​​for the state of charge SOC and the battery temperature T are set according to the value of the C rate. cell A table with MidDCR values ​​is set for each combination of . That is, if the C rate value is expressed as C as above, k (k=1~N), then for each C k The same table as the intermediate DCR table 608 described in the first embodiment is set, and the total number of the tables is N. The value of MidDCR in each table is set to the corresponding C k The value of MidDCR can be set for both Ro and Rp.

[0117] The intermediate voltage calculation unit 502a obtains the current state of charge SOC of the battery pack 101 and the battery temperature T from the intermediate OCV table group 610 and the intermediate DCR table group 611. cell And the intermediate OCV and intermediate DCR values ​​corresponding to the C rate value.

[0118] The gain setting unit 612 sets the rated capacity Ah of (Formula 12) described in the first embodiment. rated As the gain of the C rate for the input. Then, multiply the C rate value by the rated capacity Ah rated , from which the discharge current I is calculated Ck,DCh .

[0119] The intermediate voltage calculation unit 502a calculates the intermediate OCV and intermediate DCR values ​​obtained from the intermediate OCV table group 610 and the intermediate DCR table group 611, respectively, and the discharge current I output from the gain setting unit 612. Ck,DCh and SOHR for MidDCR (corrected SOHR) are calculated by the following (Equation 13): 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)×Ah rated .

[0120] MidVoltage(t)=MidOCV(t)-I Ck,DCh ×MidDCR(t)×SOHR for MidDCR(t) / 100

[0121] (Equation 13)

[0122] Similar to (Equation 6) described in the first embodiment, in (Equation 13), MidVoltage(t) represents the intermediate voltage value at the current time t. Furthermore, MidOCV(t) and MidDCR(t) represent the intermediate OCV and intermediate DCR values ​​at the current time t, respectively, obtained from the intermediate OCV table group 610 and the intermediate DCR table group 611. SOHR for MidDCR(t) represents the corrected SOHR value at time t.

[0123] Furthermore, in this embodiment, as in the first embodiment, MidOCV(t) and MidDCR(t) of (Equation 13) can be obtained from the intermediate OCV table group 610 and the intermediate DCR table group 611 by interpolation, that is, the current state of charge SOC and battery temperature T cell The corresponding intermediate OCV and intermediate DCR values ​​are obtained. Therefore, for the C rate, state of charge SOC, and battery temperature T that are not recorded in the intermediate OCV table group 610 and the intermediate DCR table group 611, the corresponding intermediate OCV and intermediate DCR values ​​are obtained. cell The appropriate voltage and resistance values ​​can be obtained as the intermediate OCV and intermediate DCR by the combination of .

[0124] For example, the state of charge SOC at time t, the battery temperature T cell and C rate values ​​are expressed as SOC(t), T cell (t), C(t), and they satisfy the following relationship (Formula 14). In this case, with SOC(t), T cell MidOCV(t) and MidDCR(t) corresponding to the combination of (t) and C(t) are not recorded in the intermediate OCV table group 610 and the intermediate DCR table group 611.

[0125] T i <T cell (t)<T i+1

[0126] SOC j <SOC(t)<SOC j+1

[0127] C k <C(t)<C k+1 (Equation 14)

[0128] In the above case, the intermediate voltage calculation unit 502a first uses the intermediate OCV table group 610 corresponding to the C k and C k+1 The table corresponding to C(t) is calculated by interpolation based on the two tables. Then, in the calculated table, MidOCV i,j (C k ,C k+1 ), MidOCV i+1,j (C k ,C k+1 ), MidOCV i,j+1 (C k ,C k+1 ), MidOCV i+1,j+1 (C k ,C k+1 ) to extract the corresponding T i or T i+1 With SOC j or SOC j+1 The four voltage values ​​of the four combinations can be used to determine MidOCV(t) at time t by interpolation using the following (Equation 15).

[0129] MidOCV(t)=f(SOC(t),T cell (t),MidOCV i,j (C k ,C k+1 ),MidOCV i+1,j (C k ,C k+1 ),MidOCV i,j+1 (C k ,C k+1 ),MidOCV i+1,j+1 (C k ,C k+1 )) (Formula 15)

[0130] Furthermore, the intermediate voltage calculation unit 502a first uses the intermediate DCR table group 611 corresponding to the C k and C k+1 The table corresponding to C(t) is calculated by interpolation using the two tables of 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 )、MidDCRi+1,j+1 (C k ,C k+1 ) to extract the corresponding T i or T i+1 With SOC j or SOC j+1 The four resistance values ​​of the four combinations can be used to determine MidDCR(t) at time t by interpolation using the following (Equation 16).

[0131] 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 )) (Equation 16)

[0132] As long as the interpolated MidOCV(t) and MidDCR(t) are obtained as described above, the intermediate voltage calculation unit 502a can calculate the intermediate voltage MidVoltage(t) at the current time t by applying these values ​​to the aforementioned (Equation 13).

[0133] According to the second embodiment of the present invention described above, in addition to the effects (1) to (5) described in the first embodiment, the following effects are achieved.

[0134] (8) The battery management device 102 includes a C-rate calculation unit 505 for calculating the C-rate of the battery pack 101 during discharge. The intermediate voltage calculation unit 502a calculates the intermediate voltage 710 using the C-rate calculated by the C-rate calculation unit 505. Therefore, the intermediate voltage 710 can be appropriately calculated taking into account the actual driving state of the vehicle equipped with the battery pack 101.

[0135] (9) The intermediate voltage calculation unit 502a has the C rate, the state of charge SOC and the battery temperature T for the battery pack 101. cell Each combination has a voltage value MidOCV i,j The intermediate OCV table group 610 and the C rate, state of charge SOC and battery temperature T for the battery group 101 cell Each combination has a resistance value MidDCR i,jThe intermediate DCR table group 611 is obtained from the intermediate OCV table group 610 and the intermediate DCR table group 611, respectively. The C-rate value C(t) calculated by the C-rate calculation unit 505, 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 are obtained. cell The intermediate voltage MidVoltage(t) is calculated based on the voltage value MidOCV(t) and resistance value MidDCR(t) corresponding to the state of the battery pack 101. Therefore, the intermediate voltage corresponding to the state of the battery pack 101 can be easily and reliably calculated.

[0136] (10) The intermediate voltage calculation unit 502a may also obtain, by interpolation, from the intermediate OCV table group 610 and the intermediate DCR table group 611 the C-rate value C(t) calculated by the C-rate calculation unit 505, 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. cell (t) corresponds to the voltage value MidOCV(t) and the resistance value MidDCR(t). In this way, for the C rate, state of charge SOC and battery temperature T that are not recorded in the intermediate OCV table group 610 and the intermediate DCR table group 611, cell The combination of can also obtain the corresponding voltage value MidOCV(t) and resistance value MidDCR(t) in detail.

[0137] (Third embodiment)

[0138] Next, a third embodiment of the present invention will be described. Hereinafter, differences from the first embodiment will be mainly described, and descriptions of common points with the first embodiment will be omitted or simplified.

[0139] Figure 11 This is a diagram showing the functional blocks of the battery management device 102b related to the available energy calculation process according to the third embodiment of the present invention. The battery management device 102b of this embodiment includes a battery state calculation unit 501b and an intermediate voltage calculation unit 502b instead of Figure 4 The battery state calculation unit 501 and the intermediate voltage calculation unit 502 are shown. These functional blocks are realized by, for example, executing a predetermined program in a computer.

[0140] Battery state calculation unit 501 differs from battery state calculation unit 501b in the following ways. Specifically, battery state calculation unit 501b calculates SOHR for Ro and SOHR for Rp instead of the SOHR calculated by battery state calculation unit 501. SOHR for Ro is the SOHR for Ro, and SOHR for Rp is the SOHR for Rp. For example, SOHR for Ro(t) = {Ro(t) / Ro,new} × 100 and SOHR for Rp(t) = {Rp(t) / Rp,new} × 100 can be used. SOHR for Ro(t) is the SOHR for Ro at time t, Ro(t) is the Ro at time t, and Ro,new is the initial Ro. SOHR for Rp(t) is the SOHR for Rp at time t, Rp(t) is the Rp at time t, and Rp,new is the initial Rp.

[0141] The intermediate voltage calculation unit 502 and the intermediate voltage calculation unit 502b differ in the following points: The intermediate voltage calculation unit 502b receives the SOHR for Ro and SOHR for Rp calculated by the battery state calculation unit 501a instead of the SOHR.

[0142] Figure 12 The diagram shows the functional blocks of the intermediate voltage calculation unit 502b according to the third embodiment of the present invention. The intermediate voltage calculation unit 502b includes a SOHR correction unit 1610a instead of Figure 7 The SOHR correction unit 1610 is shown.

[0143] SOHR correction unit 1610 differs from SOHR correction unit 1610a in the following ways. SOHR correction unit 1610a receives SOHR for Ro and SOHR for Rp calculated by battery state calculation unit 501a in place of SOHR. SOHR correction unit 1610a calculates SOHR for MidDCR based on SOHR for Ro and SOHR for Rp. SOHR for MidDCR can be based on, for example, SOHR for Ro and its weight A, and SOHR for Rp and its weight B. Weights A and B can be either absolute 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 13).

[0144] SOHR_for MidDCR=A×SOHR for Ro+B×SOHR_for Rp (Equation 17)

[0145] The weights A and B may be constants or variable values ​​that change according to parameters such as battery temperature. The parameters mentioned here may be parameters determined based on experimental results of discharge at C rates at various battery degradation levels, for example.

[0146] According to the second embodiment of the present invention described above, in addition to the effects (1) to (7) described in the first embodiment, the following effects are achieved.

[0147] (11) The calculated resistance degradation degree SOHR is the internal resistance degradation degree SOHR for Ro, which is the degradation degree of the internal resistance 604 of the battery pack 101, and the polarization resistance degradation degree SOHR for Rp, which is the degradation degree of the polarization resistance 606 of the battery pack 101. The intermediate voltage calculation unit 502b calculates the corrected resistance degradation degree (SOHR for MidDCR) based on the calculated SOHR for Ro, the weight A of the SOHR for Ro, the calculated SOHR for Rp, and the weight B of the SOHR for Rp. Therefore, both Ro and Rp are reflected in the corrected SOHR, so the accuracy of the SOHR, which is one of the elements of the calculation of the available energy, is improved. As a result, it can be expected that the accuracy of the calculated available energy will be high.

[0148] Furthermore, in the above-mentioned embodiments, the application examples in the power storage system installed in electric vehicles, hybrid vehicles, etc. are described, but the present invention can also be similarly applied to power storage systems used for other purposes, such as power storage systems connected to the power transmission network.

[0149] In addition, in the above embodiments, the calculation method of the available energy when discharging the battery pack 101 is described, but the same calculation method can be applied to the chargeable energy when charging the battery pack 101. Here, the so-called chargeable energy is defined as the total amount of electric energy that can be stored when charging the battery pack 101 from a certain charging state. This is equivalent to charging each battery cell of the battery pack 101 with a certain charging current, and the SOC of each battery cell becomes the maximum SOC value allowed for each battery cell, that is, the SOC max The total amount of electricity (Wh) that can be charged to each battery cell during the period up to

[0150] When applying to calculation of chargeable energy, Figure 3 The intermediate voltage 710 described above represents the current SOC of the battery pack 101 and the SOC max The charging curve of the change of charging voltage until the end of charging exists in the voltage value corresponding to the current SOC and the SOC corresponding to the end of charging. maxTherefore, the intermediate voltage 710 is multiplied by the current SOC and SOC max The value of the charge capacity obtained by the difference between the current SOC and the SOC max The intermediate voltage 710 is calculated so that the integral value of the charging curve up to the current value matches the current value. Specifically, the intermediate voltage during charging can be calculated using an intermediate voltage calculation unit similar to the intermediate voltage calculation unit 502 described in the first embodiment or the intermediate voltage calculation unit 502a described in the second embodiment. Furthermore, since the intermediate voltage (CCV) during charging increases relative to the intermediate OCV by a voltage corresponding to the internal resistance, the aforementioned (Equation 6) and (Equation 13) can be modified and used as follows (Equation 6') and (Equation 13'), respectively.

[0151] MidVoltage(t)=MidOCV(t)+I C0,DCh ×MidDCR(t)×SOHR for MidDCR(t) / 100

[0152] (Formula 6')

[0153] MidVoltage(t)=MidOCV(t)+I Ck,DCh ×MidDCR(t)×SOHR for MidDCR(t) / 100(Formula 13')

[0154] The chargeable energy can be calculated by multiplying the intermediate voltage during charging obtained in this way by the chargeable capacity obtained by the following (Formula 18). In Formula (18), ChargeableCapacity(t) represents the value of the chargeable capacity at the current time t. In addition, Ah rated The rated capacity of the battery pack 101 , that is, the remaining capacity when the battery pack 101 is fully charged at the start of use.

[0155] ChargeableCapacity(t)={(SOC max -SOC(t)) / 100}×Ah rated ×SOHQ for MidDCR(t) / 100 (Equation 18)

[0156] Furthermore, the third embodiment can be applied to the second embodiment in addition to the first embodiment. Figure 2The battery state calculation unit 501 in the embodiment of the present invention is replaced with the battery state calculation unit 501b in the third embodiment. In addition, the SOHR correction unit 1610 in the second embodiment can be replaced with the SOHR correction unit 1610a in the third embodiment. When the third embodiment is reflected in the second embodiment, in addition to the above-mentioned effects (1) to (5) and (8) to (11), the above-mentioned effect (11) is also achieved.

[0157] The present invention can be modified in various ways without departing from the spirit of the present invention, and is not limited to the above-described embodiment and modifications.

[0158] Explanation of symbols

[0159] 1…Battery Electricity Storage System (BESS)

[0160] 2…Converter

[0161] 3…Load

[0162] 4…Upper controller

[0163] 101…Battery Pack

[0164] 102, 102a, 102b…battery management device

[0165] 103…Current sensor

[0166] 104…Unit controller

[0167] 105…voltage sensor

[0168] 106…Temperature sensor

[0169] 107…Relay

[0170] 501, 501a...Battery status calculation unit

[0171] 502, 502a, 502b...Intermediate voltage calculation unit

[0172] 503 ...Remaining capacity calculation unit

[0173] 504…Available energy calculation unit

[0174] 505…C rate calculation unit

[0175] 601…Battery Model Department

[0176] 602…Degradation state detection unit

[0177] 603…No-load voltage source

[0178] 604…Internal resistance

[0179] 605…Polarized capacitor

[0180] 606…Polarization resistor

[0181] 607…Intermediate OCV table

[0182] 608…Intermediate DCR table

[0183] 609…Discharge current setting unit

[0184] 610…Intermediate OCV meter set

[0185] 611…Intermediate DCR table group

[0186] 612…Gain setting unit

[0187] 1610, 1610a…SOHR Correction Department.

Claims

1. A battery management device for managing rechargeable and dischargeable batteries, characterized in that: have: a battery state calculation unit that calculates a state of charge, a capacity degradation degree, and a resistance degradation degree of the battery; an intermediate voltage calculation unit that corrects the calculated resistance degradation degree, corrects the intermediate resistance of the battery corresponding to the intermediate voltage according to a correction coefficient corresponding to the corrected resistance degradation degree, and calculates the intermediate voltage between the charge / discharge voltage in the current charge state of the battery and the charge / discharge voltage in the minimum charge state or the maximum charge state of the battery based on the corrected intermediate resistance; a remaining capacity calculation unit for calculating a remaining capacity or a chargeable capacity of the battery based on the state of charge and the degree of capacity degradation; as well as an available energy calculation unit for calculating available energy or chargeable energy of the battery based on the intermediate voltage and the remaining capacity, or the intermediate voltage and the chargeable capacity, The intermediate voltage is a voltage at which a value obtained by multiplying the intermediate voltage by the remaining capacity or the chargeable capacity coincides with an integral value of a charge and discharge curve indicating changes in the charge and discharge voltage from the current charge state to the minimum charge state or the maximum charge state.

2. The battery management device according to claim 1, characterized in that: The intermediate voltage calculation unit calculates the intermediate voltage based on an open circuit intermediate voltage corresponding to the intermediate voltage and an intermediate drop voltage which is a potential difference between both ends of the battery caused by a corrected intermediate resistance when a predetermined charge / discharge current flows.

3. The battery management device according to claim 1, characterized in that: The corrected resistance degradation degree depends on both the degradation degree of the internal resistance of the battery and the degradation degree of the polarization resistance of the battery.

4. The battery management device according to claim 3, characterized in that: The intermediate voltage calculation unit reflects factors that depend on both a degradation mechanism of the internal resistance of the battery and a degradation mechanism of the polarization resistance of the battery in the calculated resistance degradation degree, thereby correcting the calculated resistance degradation degree.

5. The battery management device according to claim 3, characterized in that: The calculated resistance degradation degree is the internal resistance degradation degree of the battery and the polarization resistance degradation degree of the battery. The intermediate voltage calculation unit calculates the corrected resistance degradation degree based on the calculated internal resistance degradation degree, the weight of the internal resistance degradation degree, the calculated polarization resistance degradation degree, and the weight of the polarization resistance degradation degree.

6. The battery management device according to any one of claims 1 to 5, characterized in that: The available energy calculation unit calculates the available 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, characterized in that: The intermediate voltage calculation unit includes a first table in which voltage values ​​are set for each combination of the battery state of charge and temperature, and a second table in which resistance values ​​are set for each combination of the battery state of charge and temperature. acquiring, from the first table and the second table, a voltage value and a resistance value corresponding to the state of charge calculated by the battery state calculation unit and the current temperature of the battery, respectively; The intermediate voltage is calculated according to the acquired voltage value and the resistance value.

8. The battery management device according to claim 7, characterized in that: The intermediate voltage calculation unit obtains a voltage value and a resistance value corresponding to the state of charge calculated by the battery state calculation unit 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, characterized in that: A C-rate calculating unit for calculating the C-rate of the battery during charge and discharge is provided. The intermediate voltage calculation unit calculates the intermediate voltage using the C-ratio calculated by the C-ratio calculation unit.

10. The battery management device according to claim 9, characterized in that: The intermediate voltage calculation unit includes a first table in which voltage values ​​are set for each combination of the battery's C rate, state of charge, and temperature, and a second table in which resistance values ​​are set for each combination of the battery's C rate, state of charge, and temperature. acquiring, from the first table and the second table, voltage values ​​and resistance values ​​corresponding to the C-rate calculated by the C-rate calculation unit, the state of charge calculated by the battery state calculation unit, and the current temperature of the battery, respectively; The intermediate voltage is calculated according to the acquired voltage value and the resistance value.

11. The battery management device according to claim 10, characterized in that: The intermediate voltage calculation unit obtains voltage values ​​and resistance values ​​corresponding to the C-rate calculated by the C-rate calculation unit, the state of charge calculated by the battery state calculation unit, and the current temperature of the battery from the first table and the second table by interpolation, respectively.

12. A battery management method for managing a rechargeable and dischargeable battery, the method being characterized in that: The state of charge, capacity degradation and resistance degradation of the battery are calculated by a computer. Correcting the calculated resistance degradation degree, Correcting the intermediate resistance of the battery corresponding to the intermediate voltage according to a correction coefficient corresponding to the corrected resistance degradation degree; The intermediate voltage between the charge / discharge voltage at the current charge state of the battery and the charge / discharge voltage at the minimum charge state or the maximum charge state of the battery is calculated based on the corrected intermediate resistance. Calculating the remaining capacity or rechargeable capacity of the battery based on the calculated state of charge and the capacity degradation degree, Calculating the available energy or the rechargeable energy of the battery based on the calculated intermediate voltage and the remaining capacity or the calculated intermediate voltage and the rechargeable capacity, The intermediate voltage is a voltage at which a value obtained by multiplying the intermediate voltage by the remaining capacity or the chargeable capacity coincides with an integral value of a charge and discharge curve indicating changes in the charge and discharge voltage from the current charge state to the minimum charge state or the maximum charge state.

13. An electric power storage system, characterized in that: have: The battery management device according to any one of claims 1 to 11; Rechargeable and dischargeable batteries; and A charging and discharging device charges and discharges the battery based on the available energy or chargeable energy of the battery calculated by the battery management device.

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