Battery management method and battery management system

Abstract

The present invention provides a battery management method capable of more appropriately controlling charging and discharging. Specifically, the temperature of a conductive member is estimated on the basis of a module temperature, a battery current value, and the material characteristics of the conductive member (including a bus bar and electrical wiring) (S103). Subsequently, a conductive member resistance value which corresponds to the estimated conductive member temperature is estimated for each conductive member by referring to correlation information which expresses a predetermined correlation between conductive member temperature and conductive member resistance value (S104).

Description

Battery management method and battery management system

[0001] This disclosure relates to a battery management method and a battery management system.

[0002] Conventionally, a system has been proposed to improve the accuracy of cell voltage by measuring the temperature of a battery module and the voltage of the cells contained in the battery module, estimating the voltage drop across the busbars connecting the cells based on the measured temperature, and correcting the measured voltage based on the estimated voltage drop (see, for example, Patent Document 1). In the system described in Patent Document 1, the voltage drop is estimated based on the calculated resistance value of the busbars and the current value of the current flowing through the battery module, calculated based on the temperature of the battery module.

[0003] Japanese Patent Publication No. 2014-117068

[0004] However, the system described in Patent Document 1 estimates the voltage drop due to the busbar based on the temperature of the battery module. Therefore, if, for example, the ambient temperature or the amount of charge / discharge changes, and the temperature of the busbar changes as a result, the difference between the temperature of the busbar and the temperature of the battery module will increase, which may reduce the accuracy of the voltage drop estimation. As a result, the accuracy of the corrected cell voltage may decrease, making it difficult to properly control charge and discharge. The purpose of this disclosure is to provide a battery management method and a battery management system that enable more appropriate control of charge and discharge.

[0005] A battery management method according to one aspect of the present disclosure is a battery management method for controlling the charging and discharging of a battery comprising a battery module having a plurality of electrically connected series cells, comprising the steps of: estimating the temperature of conductive members based on the module temperature, which is the temperature of the battery module; the battery current value, which is the current value of the current flowing through the battery; and the material properties of conductive members electrically connecting the cells; estimating the resistance value of a conductive member corresponding to the estimated temperature of a conductive member for each conductive member by referring to correspondence relationship information that shows the correspondence relationship between the temperature of a conductive member and the resistance value of a conductive member; and for each cell, the cell The system includes the steps of: obtaining the pre-correction cell voltage from a voltage detection unit that detects the pre-correction cell voltage, which is the voltage difference between a predetermined point on a conductive member connected to the positive electrode and a predetermined point on a conductive member connected to the negative electrode; calculating the amount of voltage drop due to the resistance of the conductive member for each cell, based on the estimated resistance value of the conductive member that causes a voltage drop in the pre-correction cell voltage of the cell, and the battery current value; correcting the pre-correction cell voltage obtained from the voltage detection unit based on the calculated amount of voltage drop; and controlling the charging and discharging of the battery based on the corrected pre-correction cell voltage, which is the corrected post-correction cell voltage.

[0006] This disclosure provides a battery management method and a battery management system that enable more appropriate control of charging and discharging.

[0007] This is a diagram showing the overall configuration of the battery management system of the embodiment. This is a diagram showing the internal configuration of the battery and battery module. This is a diagram showing the data contents of the first map. This is a diagram showing the data contents of the second map. This is a diagram showing the resistance of the conductive member estimated by the resistance estimation unit. This is a flowchart showing the overall flow of the battery management method of the embodiment. This is a diagram showing the corrected cell voltage when the battery is being charged. This is a diagram showing the corrected cell voltage when the battery is being discharged. This is a flowchart showing the overall flow of the battery management method of modification (1). This is a diagram showing the overall configuration of the battery management system of modification (2). This is a flowchart showing the overall flow of the battery management method of modification (2).

[0008] The embodiments of this disclosure will be described below with reference to the drawings. Note that the drawings are schematic and may differ from actual ones. Furthermore, the embodiments of this disclosure shown below are illustrative examples of devices and methods for realizing the technical concept of this disclosure, and the technical concept of this disclosure is not limited to the structure, arrangement, etc., of the components described below. The technical concept of this disclosure can be modified in various ways within the technical scope defined by the claims described in the patent claims.

[0009] (Configuration) In this embodiment, as shown in Figure 1, an example is given in which the battery management method and battery management system of this disclosure are applied to a battery management system 1 that controls the charging and discharging of a battery. Such a battery management system 1 is mounted on a vehicle, for example, and used to control the charging and discharging of a battery for driving. Figure 1 is a diagram showing the overall configuration of the battery management system 1 of this embodiment. As shown in Figure 1, the battery management system 1 comprises a battery 2, a battery state detection unit 3, and a control unit 4.

[0010] The battery 2 has multiple battery modules 5 that are electrically connected in series and / or parallel. Each battery module 5 has multiple cells 6 that are electrically connected in series, as shown in Figure 2. For example, lithium-ion secondary batteries and all-solid-state secondary batteries can be used as cells 6. Figure 2 illustrates a case in which there are two battery modules 5, and six cells 6 are arranged in rows within each battery module 5 to form two cell rows. Within each cell row, each cell 6 is arranged so that its positive and negative electrodes are staggered. Figure 2 is a diagram showing the internal configuration of the battery 2 and the battery modules 5.

[0011] Furthermore, within the same cell row, a first conductive member 7a (hereinafter also referred to as "bus bar 7a") is arranged between the positive electrode of one adjacent cell 6 and the negative electrode of the other adjacent cell 6, bridging the gap between the positive and negative electrodes. In this way, the bus bar 7a electrically connects multiple cells 6 within the same battery module 5. In addition to (1) a bus bar 7a that connects adjacent cells 6 within the same cell row (7aa in Figure 2), there are also (2) a bus bar 7a that connects different cell rows within the same battery module 5 (7ab in Figure 2), (3) a bus bar 7a that serves as the positive output terminal of the battery module 5 (7ac in Figure 2), and (4) a bus bar 7a that serves as the negative output terminal of the battery module 5 (7ad in Figure 2). In the following explanation, each cell 6 will be assigned a cell number such as C1, C2, C3, etc. For example, cell 6 with cell number C1 will be called "cell C1," and cell 6 with cell number C2 will be called "cell C2." In Figure 2, the positive terminal side of cell C1 in one battery module 5 (the battery module 5 on the left in Figure 2) is the positive output terminal of the battery 2. The negative terminal side of cell C24 in the other battery module 5 (the battery module 5 on the right in Figure 2) is the negative output terminal of the battery 2. A second conductive member 7b (hereinafter also called "electrical wiring 7b") is arranged between the busbar 7a connected to the negative terminal of cell C12 in one battery module 5 and the busbar 7a connected to the positive terminal of cell C13 in the other battery module 5, spanning across these busbars 7a. As a result, the electrical wiring 7b electrically connects the cells 6 in the different battery modules 5. In the following explanation, the first conductive member 7a and the second conductive member 7b will also be referred to as "conductive member 7". That is, conductive member 7 includes the first conductive member 7a and the second conductive member 7b.

[0012] As shown in Figure 1, the battery state detection unit 3 includes a microcontroller (not shown) and a storage device. The battery state detection unit 3 comprises a voltage detection unit 8, a current detection unit 9, a temperature detection unit 10, a storage unit 11, a temperature estimation unit 12, a resistance estimation unit 13, a voltage drop calculation unit 14, and a correction unit 15. The voltage detection unit 8 has a plurality of voltage detection lines 16. Each of the plurality of voltage detection lines 16 is connected to a predetermined location P on the busbar 7a, as shown in Figure 2. The voltage detection unit 8 then detects the voltage difference (hereinafter also called "pre-correction cell voltage Vc") between predetermined locations P on two busbars 7a connected to the cell 6 whose output voltage is to be detected, via the voltage detection lines 16. As a result, the voltage detection unit 8 detects the voltage difference (pre-correction cell voltage Vc) between a predetermined location P on the busbar 7a connected to the positive terminal of the cell 6 and a predetermined location P on the busbar 7a connected to the negative terminal for each cell 6. In Figure 2, a predetermined point P is set on the busbar 7a, directly above the positive terminal of cell 6. For each cell 6, the voltage difference is detected between the predetermined point P on the busbar 7a connected to the positive terminal of cell 6 and the predetermined point P on the busbar 7a connected to the negative terminal, which is set directly above the positive terminal of the adjacent cell 6. The pre-correction cell voltage Vc is smaller than the actual output voltage of cell 6 by the amount of voltage drop due to the resistance R of the busbar 7a. The signal indicating the pre-correction cell voltage Vc is output to the correction unit 15. The correction unit 15 then obtains the pre-correction cell voltage Vc from the voltage detection unit 8.

[0013] The current detection unit 9 detects the current value of the current flowing through the battery 2 (hereinafter also referred to as "battery current value I") and outputs a signal indicating the detected value. Figure 1 illustrates a case where the current detection unit 9 is a Hall-type sensor that detects the current value of the current flowing through the output terminals of the battery 2. The signal indicating the battery current value I is output to the temperature estimation unit 12, the voltage drop calculation unit 14, and the control unit 4. The temperature detection unit 10 has a plurality of thermistors 17 (temperature sensors). Each of the plurality of thermistors 17 is arranged in each battery module 5 as shown in Figure 1. The temperature detection unit 10 then detects the temperature of the battery module 5 to be detected (hereinafter also referred to as "module temperature Tm") based on the output signals from the thermistors 17. In this way, the temperature detection unit 10 detects the module temperature Tm for each battery module 5. The signal indicating the module temperature Tm is output to the temperature estimation unit 12 and the control unit 4.

[0014] As shown in Figure 3A, the memory unit 11 stores a first map of combinations between the cell number of each cell 6 and the conductive member 7 group (bus bar 7a, electrical wiring 7b) that causes a voltage drop in the cell voltage Vc of cell 6 before correction. For example, the bus bar 7aa for cell connection within the same cell row is associated with cell numbers C1 to C5, C7 to C11, C13 to C17, and C19 to C23. In Figure 2, two bus bars, 7aa and 7ac, are connected to cell C1. However, in Figure 2, a predetermined location P of the bus bar 7ac is directly above cell C1, so the effect of the voltage drop by the bus bar 7ac on the cell voltage Vc of cell C1 before correction is almost "0". Therefore, in Figure 3A, the bus bar 7ac is not associated with cell number C1. Similarly, the bus bar 7a, which has an effect of almost "0" on the voltage drop, is not associated with the other cell numbers C2 to C24. Furthermore, cell numbers C6 and C18 are associated with busbars 7ab for inter-column connections. Cell number C12 is associated with a series connection of the negative terminal busbar 7ad of the battery module 5, the positive terminal busbar 7ac of the battery module 5, and electrical wiring 7b. Cell number C24 is associated with the negative terminal busbar 7ad of the battery module 5. Figure 3A shows the data contents of the first map.

[0015] Furthermore, as shown in Figure 3B, the memory unit 11 stores a second map in which each conductive member 7 is associated with the resistance value of the conductive member 7 (the resistance value that causes a voltage drop). For example, the bus bar 7aa is associated with a constant table Ta that shows the correspondence between the temperature T of the bus bar 7aa and its resistance value Ra. That is, the memory unit 11 stores multiple constant tables Ta (hereinafter also called "correspondence information") as a second map, which show the correspondence between the temperature of the conductive member 7 and the resistance value of the conductive member 7 that has been predetermined. Also, the bus bar 7ab is associated with a constant table Tb. Also, the series connection of bus bars 7ac, 7ad and electrical wiring 7b is associated with a constant table Tc. Also, the bus bar 7ad for the negative electrode is associated with a constant table Td. Figure 3B is a diagram showing the data contents of the second map. Note that, for example, a mathematical formula showing the relationship between the temperature and resistance value of the conductive member 7 may be used as the correspondence information. Furthermore, the memory unit 11 stores the material properties of the conductive member 7. Examples of material properties include the heat generation coefficient Q and the heat dissipation coefficient λ of the conductive member 7.

[0016] The temperature estimation unit 12 estimates the temperature T of the conductive member 7 based on the battery current value I detected by the current detection unit 9, the module temperature Tm detected by the temperature detection unit 10, and the material properties of the conductive member 7 stored in the memory unit 11. As a result, the temperature estimation unit 12 detects the temperature T for each group of conductive member 7 in the first map shown in Figure 3A. For example, the module temperature Tm can be the temperature of the battery module 5 with the lowest temperature among multiple battery modules 5. As a method for estimating the temperature T of the conductive member 7 (hereinafter also referred to as the "first method"), for example, a method can be employed in which the amount of heat generated by the conductive member 7 is calculated based on the battery current value I and the heat generation coefficient Q, and the temperature T of the conductive member 7 is estimated based on the calculated amount of heat generated and the module temperature Tm. Furthermore, as another method for estimating the temperature T of the conductive member 7 (hereinafter also referred to as the "second method"), for example, a method can be employed in which the amount of heat dissipated by the conductive member 7 is calculated based on the module temperature Tm and the heat dissipation coefficient λ, and the temperature T of the conductive member 7 is estimated based on the calculated amount of heat dissipation. Furthermore, the first and second methods may be combined to estimate the temperature T of the conductive member 7 based on both the heat generation and module temperature calculated by the first method and the heat dissipation amount calculated by the second method. In this case, the temperature T of the conductive member 7 is estimated according to the following equation (1), based on the previous temperature Told of the conductive member 7, the heat generation coefficient Q, the battery current value I, the heat dissipation coefficient λ, and the module temperature Tm, thermal resistance r, heat capacity Cp, heat transfer coefficient h, and surface area A. T = Told + ΔT / Δt ………(1) ΔT / Δt = Q・I 2 -λ(Told-Tm) Q=r / Cp, λ=h・A / Cp

[0017] In equation (1) above, the previous temperature Told of the conductive member 7 (i.e., the previously estimated temperature T of the conductive member 7) is required to calculate the temperature T of the conductive member 7. Therefore, for example, if the vehicle system is stopped and the estimation of the temperature T of the conductive member 7 is stopped, the previous temperature Told does not exist, and therefore the temperature T of the conductive member 7 cannot be calculated from equation (1) above. For this reason, the temperature of the conductive member 7 when estimation of the temperature T of the conductive member 7 is resumed after being stopped (hereinafter also referred to as "initial temperature Tini") may be estimated based on the time t from when the estimation was stopped to when the estimation was resumed, and the temperature of the conductive member 7 estimated immediately before the estimation was stopped (hereinafter also referred to as "temperature just before sleep To"). In this case, the initial temperature Tini is estimated according to equation (2) below, based on the module temperature Tm at the time the estimation of temperature T is resumed, the temperature just before sleep To, and the coefficient τ. Tini = Tm + (To - Tm) * exp((-1 / τ) * t) ……… (2)

[0018] The resistance estimation unit 13 refers to the second map (correspondence relationship information) stored in the memory unit 11 and estimates the resistance value R of each conductive member 7 corresponding to the temperature T of the conductive member 7 estimated by the temperature estimation unit 12. As a method for estimating the resistance value R of the conductive member 7, for example, first, one cell 6 is identified, the first map stored in the memory unit 11 is referred to, and a conductive member 7 that causes a voltage drop in the uncorrected cell voltage Vc of the identified cell 6 is selected. Next, from among multiple correspondence relationship information (constant table Ta, etc.), correspondence relationship information (constant table Ta, etc.) corresponding to the selected conductive member 7 (hereinafter also referred to as "specific conductive member 7") is extracted. Next, based on the extracted correspondence relationship information (constant table Ta, etc.), the resistance value R corresponding to the temperature T of the specific conductive member 7 is estimated and set as the resistance value R of the specific conductive member 7. Then, the above procedure of selecting cell 6 and calculating the resistance value R is repeated for all cells 6.

[0019] In this case, as shown in Figure 4, the resistance estimation unit 13 determines that the temperature T of the conductive member 7 (specific conductive member 7) estimated by the temperature estimation unit 12 is within a predetermined temperature range G. inf ~G sup Upper limit Gsup If it is larger than, the estimated result of the resistance value R of the specific conductive member 7 is set to the maximum value R MAX predetermined. Also, for the temperature range G inf to G sup if it is smaller than the lower limit value G inf of, the estimated result of the resistance value R of the specific conductive member 7 is set to the minimum value R MIN predetermined. As the temperature range G inf to G sup for example, a temperature range of -30°C or more and 120°C or less can be adopted.

[0020] The voltage drop calculation unit 14 calculates, for each cell 6, the resistance value R of the conductive member 7 that causes a voltage drop in the pre-correction cell voltage Vc of the cell 6 among the resistance values R of the conductive member 7 estimated by the resistance estimation unit 13, and based on the battery current value I detected by the current detection unit 9, the voltage drop V R of the pre-correction cell voltage Vc due to the resistance value R of the conductive member 7. As a method for calculating the voltage drop V R for example, first, one cell 6 is specified, the first map stored in the storage unit 11 is referred to, and the conductive member 7 that causes a voltage drop in the pre-correction cell voltage Vc of the specified cell 6 is selected. Subsequently, the battery current value I is multiplied by the resistance value R (the value estimated by the resistance estimation unit 13) of the selected conductive member 7 to obtain the voltage drop V R of the pre-correction cell voltage Vc of the specified cell 6. Then, for all cells 6, the above-described procedure of cell 6 selection - voltage drop V R calculation is repeatedly executed.

[0021] At that time, the voltage drop calculation unit 14 refers to the first map in FIG. 3A and determines whether there are two or more cells 6 connected to the same type of conductive member 7 as the conductive member 7 that causes a voltage drop. And if there are such two or more cells 6, among the two or more cells 6, the voltage drop V R of the pre-correction cell voltage Vc of one cell 6 is calculated, and the calculated voltage drop V R is adopted as the voltage drop V R of the pre-correction cell voltage Vc of each of the two or more cells 6.

[0022] The correction unit 15 calculates the voltage drop amount V for each cell 6, which is calculated by the voltage drop amount calculation unit 14. R Based on this, the uncorrected cell voltage Vc obtained from the voltage detection unit 8 is corrected. As a method for correcting the uncorrected cell voltage Vc, for example, first, one cell 6 is identified, and the uncorrected cell voltage Vc of the identified cell 6 is set by the voltage drop amount V of the identified cell 6. R The value calculated by the voltage drop calculation unit 14 is added to obtain the corrected cell voltage Vc'. Then, the procedure of selecting cell 6 and generating the corrected cell voltage Vc' is repeated for all cells 6. That is, for each cell 6, the voltage drop calculation unit 14 and the correction unit 15 calculate the voltage drop amount due to the resistance value R of the conductive member 7, which causes a voltage drop in the cell voltage Vc of cell 6 from the estimated resistance value of the conductive member 7, and the battery current value I, for each cell 6. R The calculated voltage drop V R Based on this, the uncorrected cell voltage Vc obtained from the voltage detection unit 8 is corrected.

[0023] The control unit 4 controls the charging and discharging of the battery 2 based on the battery current value I detected by the current detection unit 9, the module temperature Tm detected by the temperature detection unit 10, and the corrected cell voltage Vc' corrected by the correction unit 15. As a method for controlling the charging and discharging of the battery 2, for example, when charging the battery 2, if any of the corrected cell voltages Vc' reach an overcharge threshold, a method can be adopted to prohibit charging of cell 6 so that cell 6 does not become overcharged. Another method for controlling the charging and discharging of the battery 2 is to adopt a method, for example, when discharging the battery 2, if any of the corrected cell voltages Vc' reach an over-discharge threshold, a method can be adopted to prohibit discharging of cell 6 so that cell 6 does not become over-discharged.

[0024] (Operation) Next, the flow of the process for controlling the charge and discharge of the battery 2 will be described. First, the voltage detection unit 8 selects one cell 6 from among the plurality of cells 6 included in the battery 2 during charging or discharging of the battery 2 (S101 in FIG. 5). FIG. 5 is a flowchart showing the overall flow of the battery management method of the present embodiment. Subsequently, the voltage detection unit 8 detects the pre-correction cell voltage Vc of the selected cell 6 (hereinafter also referred to as "selected cell 6") (S102 in FIG. 5). Subsequently, the temperature estimation unit 12 refers to the first map stored in the storage unit 11 and extracts the conductive member 7 (hereinafter also referred to as "influencing conductive member 7") that causes a voltage drop in the pre-correction cell voltage Vc of the selected cell 6. For example, when the selected cell 6 selected in S101 is cell C1, the bus bar 7a for cell connection in the same cell row is extracted as the influencing conductive member 7. Subsequently, based on the material characteristics of the extracted influencing conductive member 7, the battery current value I, and the module temperature Tm, the temperature T of the influencing conductive member 7 is estimated (S103 in FIG. 5). As an example of the module temperature Tm, the temperature of the battery module 5 with the lowest temperature is adopted.

[0025] Subsequently, the resistance estimation unit 13 refers to the second map stored in the storage unit 11 and extracts the corresponding relationship information (constant table Ta, etc.) corresponding to the extracted influencing conductive member 7. Subsequently, the resistance estimation unit 13 calculates the resistance value R of the influencing conductive member 7 based on the extracted corresponding relationship information and the temperature T of the influencing conductive member 7 estimated in S103 (S104 in FIG. 5). Subsequently, the voltage drop amount calculation unit 14 calculates the voltage drop amount V due to the resistance value R of the influencing conductive member 7 based on the calculated resistance value R and the battery current value I R (S105 in FIG. 5). At that time, if the voltage drop amount V R of the conductive member 7 of the same type as the influencing conductive member 7 has been calculated between the start of the arithmetic processing shown in the flowchart of FIG. 5 and the present time, the calculated voltage drop amount V R is used as the voltage drop amount V R of the selected cell 6. Subsequently, the correction unit 15 calculates the calculated voltage drop amount V RThe corrected cell voltage Vc' is generated by adding the corrected cell voltage Vc' to the uncorrected cell voltage Vc of the selected cell 6 (S106 in Figure 5). Subsequently, it is determined that there are cells 6 for which the corrected cell voltage Vc' has not been generated (S107 "No" in Figure 5), and the process returns to S101. The unselected cell 6 from S101 is selected, and the above flow from S101 to S106 is executed again. As the above flow from S101 to S106 is repeated, the corrected cell voltage Vc' is generated for all cells 6 (S107 "Yes" in Figure 5), at which point the control unit 4 controls the charging and discharging of the battery 2 based on the battery current value I, module temperature Tm, and corrected cell voltage Vc' (S108 in Figure 5). The above flow from S101 to S108 is then repeated again starting from S101.

[0026] (Effects of this embodiment) (1) Here, as a comparative example, the voltage drop amount V due to the conductive member 7 based on the module temperature Tm R Let's consider a configuration that estimates the following. In this case, for example, if the ambient temperature or charge / discharge amount changes, and the temperature T of the conductive member 7 changes as a result of these changes, the difference between the temperature T of the conductive member 7 and the temperature Tm of the battery module 5 will increase, and the voltage drop V will increase. R There was a possibility that the estimation accuracy would decrease. As a result, as shown in Figures 6A and 6B, the accuracy of the corrected cell voltage Vc' would decrease, making it difficult to properly control charging and discharging. Figure 6A shows the corrected cell voltage Vc' of battery 2 during charging. Figure 6B shows the corrected cell voltage Vc' of battery 2 during discharging. Figure 6A illustrates a case where the corrected cell voltage Vc' of the comparative example reaches the upper limit voltage earlier than the actual output voltage of cell 6, resulting in reduced regenerative power and charging power, and preventing cell 6 from performing to its full potential. Figure 6B illustrates a case where the corrected cell voltage Vc' of the comparative example reaches the lower limit voltage earlier than the actual output voltage of cell 6, resulting in reduced discharge power, and preventing cell 6 from performing to its full potential.

[0027] In contrast, in this embodiment, the temperature T of the conductive member 7 is estimated based on the module temperature Tm, the battery current value I, and the material properties of the conductive member 7 (including the busbar 7a and electrical wiring 7b). Subsequently, a correspondence relationship information (constant table Ta, etc.) showing the correspondence between the temperature of the conductive member 7 and the resistance value of the conductive member 7 is referenced, and the resistance value R of the conductive member 7 corresponding to the estimated temperature T of the conductive member 7 is estimated for each conductive member 7. Thus, the resistance value R of the conductive member 7 is estimated based on the temperature T of the conductive member 7. Therefore, the voltage drop V due to the resistance value R of the conductive member 7 is... R This allows for more accurate calculation of the corrected cell voltage Vc', enabling more precise calculation of the corrected cell voltage Vc'. As a result, the charging and discharging of the battery 2 can be controlled more appropriately. Consequently, as shown in Figures 6A and 6B, the regenerative power, charging power, and discharging power to the battery 2 can be increased. Figure 6A illustrates a case where the corrected cell voltage Vc' of this embodiment is calculated to be lower than the corrected cell voltage Vc' of the comparative example, making it less likely for the regenerative power and charging power to be reduced and allowing the cell 6 to perform to its full potential. Figure 6B illustrates a case where the corrected cell voltage Vc' of this embodiment is calculated to be higher than the corrected cell voltage Vc' of the comparative example, making it less likely for the discharging power to be reduced and allowing the cell 6 to perform to its full potential.

[0028] (2) In this embodiment, in the step of estimating the temperature T of the conductive member 7, the module temperature Tm used to estimate the temperature T of the conductive member 7 is the temperature of the battery module 5 with the lowest temperature among the multiple battery modules 5. As a result, the temperature of the conductive member 7 is estimated based on the lowest temperature of the battery module 5, and the temperature of the conductive member 7 is estimated to be lower. Therefore, overcorrection of the uncorrected cell voltage Vc can be prevented, and the safety of the battery 2 can be ensured.

[0029] (3) In this embodiment, the material properties include the heat generation coefficient Q of the conductive member 7. In the step of estimating the temperature T of the conductive member 7, the amount of heat generated by the conductive member 7 is calculated based on the battery current value I and the heat generation coefficient Q, and the temperature T of the conductive member 7 is estimated based on the calculated amount of heat generated and the module temperature Tm. As a result, the temperature T of the conductive member 7 is estimated based on the amount of heat generated by the conductive member 7. Therefore, the temperature T of the conductive member 7 can be estimated with higher accuracy, the resistance value R of the conductive member 7 can be estimated with higher accuracy, and the uncorrected cell voltage Vc can be corrected more appropriately.

[0030] (4) In this embodiment, the material properties include the heat dissipation coefficient λ of the conductive member 7. In the step of estimating the temperature T of the conductive member 7, the amount of heat dissipated by the conductive member 7 is calculated based on the module temperature Tm and the heat dissipation coefficient λ, and the temperature of the conductive member 7 is estimated based on the calculated amount of heat dissipated and the battery current value I. As a result, the temperature T of the conductive member 7 is estimated based on the amount of heat dissipated by the conductive member 7. Therefore, the temperature T of the conductive member 7 can be estimated with higher accuracy, the resistance value R of the conductive member 7 can be estimated with higher accuracy, and the uncorrected cell voltage Vc can be corrected more appropriately.

[0031] (5) In this embodiment, in the step of estimating the temperature T of the conductive member 7, the temperature of the conductive member 7 when estimation is resumed after being stopped is estimated based on the time t from when estimation was stopped to when estimation was resumed and the temperature To of the conductive member 7 estimated immediately before estimation was stopped. This makes it possible to estimate the initial value of the temperature T of the conductive member 7 while the vehicle system is stopped. Therefore, the temperature of the conductive member 7 can be estimated with higher accuracy and the uncorrected cell voltage Vc can be corrected more appropriately.

[0032] (6) In this embodiment, the voltage drop amount V of the pre-correction cell voltage Vc for each cell 6 R In the step of calculating the voltage drop, if there are two or more cells 6 to which the same type of conductive member 7 is associated as the conductive member 7 that causes the voltage drop, the voltage drop amount V of the pre-correction cell voltage Vc of one of the two or more cells 6 is calculated. R The calculated voltage drop V RThe voltage drop V of the uncorrected cell voltage Vc of each of the two or more cells 6. R This will be adopted. As a result, for example, the voltage drop amount V of the pre-correction cell voltage Vc for each of the 6 cells will be R Compared to the method of calculating, this method can reduce unnecessary calculations. That is, if the types of conductive material 7 can be classified into several types, the voltage drop V for each classification can be calculated. R Since they are the same, for example, the voltage drop V for each cell 6 R Calculating this would result in unnecessary computational load.

[0033] (7) In this embodiment, in the step of estimating the resistance value R of the conductive member 7, the temperature of the estimated conductive member 7 is within a predetermined temperature range T inf ~T sup Upper limit T sup If it is greater than, the estimated resistance value R of the conductive member 7 is set to a predetermined maximum value R. MAX Set to temperature range T inf ~T sup Lower limit T inf If it is smaller than this, the estimated value of the resistance R of the conductive member 7 is set to a predetermined minimum value R. MIN This setting prevents the estimation of the resistance value R of the conductive member 7 from being based on unreliable values, such as when the estimated temperature T of the conductive member 7 is an unreliable value like an extremely high or extremely low temperature. Furthermore, the resistance value R of the conductive member 7 is set to a predetermined range R. MIN ~R MAX Since it is not converted externally, overcorrection of the pre-correction cell voltage Vc can be prevented, ensuring the safety of battery 2.

[0034] (8) In this embodiment, the conductive member 7 includes a first conductive member 7a that electrically connects multiple cells 6 within the same battery module 5, and a second conductive member 7b that electrically connects cells 6 within different battery modules 5. As a result, for example, as shown in cell number C12 in Figure 3A, the busbars 7ac and 7ad (first conductive member 7a) and the electrical wiring 7b (second conductive member 7b) can be treated as a single conductive member 7, and the temperature T and resistance R of the conductive member 7 can be estimated. Therefore, unlike the case where only the first conductive member 7a is used as the conductive member 7, for example, the number of voltage detection lines 16 can be reduced. Figure 2 illustrates a case where a predetermined location P (where the voltage detection line 16 is connected) is omitted in the busbar 7ad for the negative electrode of the battery module 5 on the left.

[0035] (Modification) (1) In this embodiment, the module temperature Tm used to estimate the temperature of the conductive member 7 is shown to be the temperature of the battery module 5 with the lowest temperature among the multiple battery modules 5. However, other configurations can also be adopted. For example, as shown in Figure 7, in the step of estimating the temperature of the conductive member 7, if the battery 2 is in high-performance mode (S201 "Yes" in Figure 7), the module temperature Tm used to estimate the temperature of the conductive member 7 may be set to be the temperature of the battery module 5 with the highest temperature among the multiple battery modules 5 (S202 in Figure 7). As a result, the temperature of the conductive member 7 is estimated based on the highest temperature of the battery module 5, and the temperature of the conductive member 7 is estimated to be higher. Therefore, the degree of correction of the uncorrected cell voltage Vc can be increased, and the battery 2 can be used closer to its performance limit. Therefore, the regenerative power, charging power and discharge power to the battery can be increased. In this case, the battery 2 is configured to have a normal mode and a high-performance mode in which at least one of the regenerative capacity, charging capacity and discharge capacity is higher than in the normal mode. Figure 7 is a flowchart showing the overall flow of the battery management method in this modified example.

[0036] (2) In this embodiment, an example is shown in which the temperature T of the conductive member 7 is estimated based on the module temperature Tm, etc., but other configurations may be adopted. For example, as shown in Figure 8, each of the multiple thermistors 17 may be placed on each conductive member 7, and the temperature detection unit 10 may be configured to detect the temperature T of the conductive member 7 to be detected based on the output signal from the thermistor 17, and as shown in Figure 9, the temperature T of the conductive member 7 may be directly obtained from the temperature detection unit 10 (S301 in Figure 9). In this case, in S104 in Figure 9, the resistance estimation unit 13 calculates the resistance value R of the influencing conductive member 7 based on the extracted correspondence information (constant table Ta, etc.) and the acquired temperature T of the influencing conductive member 7. As a result, the temperature T of the conductive member 7 can be obtained with higher accuracy, the resistance value R of the conductive member 7 can be estimated with higher accuracy, and the pre-correction cell voltage Vc can be corrected more appropriately. As a result, the regenerative power, charging power, and discharge power to the battery 2 can be increased.

[0037] 1...Battery management system, 2...Battery, 3...Battery state detection unit, 4...Control unit, 5...Battery module, 5...Same battery module, 6...Selected cell, 6...Cell, 7...Specific conductive member, 7...Influencing conductive member, 7...Conductive member, 7a...First conductive member, busbar, 7b...Second conductive member, electrical wiring, 8...Voltage detection unit, 9...Current detection unit, 10...Temperature detection unit, 11...Storage unit, 12...Temperature estimation unit, 13...Resistance estimation unit, 14...Voltage drop calculation unit, 15...Correction unit, 16...Voltage detection line, 17...Thermistor

Claims

1. A battery management method for controlling the charging and discharging of a battery comprising a battery module having a plurality of electrically connected series cells, comprising: estimating the temperature of the conductive members based on the module temperature, which is the temperature of the battery module; the battery current value, which is the current value of the current flowing through the battery; and the material properties of the conductive members electrically connecting the cells; estimating the resistance value of each conductive member corresponding to the estimated temperature of the conductive member by referring to correspondence relationship information that shows the correspondence relationship between the temperature of the conductive member and the resistance value of the conductive member; and obtaining the pre-correction cell voltage from a voltage detection unit that detects the pre-correction cell voltage, which is the voltage difference between a predetermined location of the conductive member connected to the positive electrode of the cell and a predetermined location of the conductive member connected to the negative electrode of the cell, for each cell. A battery management method comprising: for each cell, calculating the amount of voltage drop due to the resistance of the conductive member based on the estimated resistance value of the conductive member that causes a voltage drop in the pre-correction cell voltage of the cell, and the battery current value; correcting the pre-correction cell voltage obtained from the voltage detection unit based on the calculated amount of voltage drop; and controlling the charging and discharging of the battery based on the corrected pre-correction cell voltage, which is the corrected pre-correction cell voltage.

2. The battery management method according to claim 1, wherein the battery includes a plurality of the battery modules, and in the step of estimating the temperature of the conductive member, the temperature of the battery module with the lowest temperature among the plurality of battery modules is adopted as the module temperature used to estimate the temperature of the conductive member.

3. The battery management method according to claim 1, wherein the material properties include the heat generation coefficient of the conductive member, and in the step of estimating the temperature of the conductive member, the amount of heat generated by the conductive member is calculated based on the battery current value and the heat generation coefficient, and the temperature of the conductive member is estimated based on the calculated amount of heat generated and the module temperature.

4. The battery management method according to claim 1, wherein the material properties include the heat dissipation coefficient of the conductive member, and in the step of estimating the temperature of the conductive member, the amount of heat dissipated by the conductive member is calculated based on the module temperature and the heat dissipation coefficient, and the temperature of the conductive member is estimated based on the calculated amount of heat dissipated and the battery current value.

5. The battery management method according to claim 4, wherein in the step of estimating the temperature of the conductive member, the temperature of the conductive member when the estimation is resumed from a state in which the estimation was stopped is estimated based on the time from when the estimation was stopped to when the estimation was resumed and the temperature of the conductive member estimated immediately before the estimation was stopped.

6. In the step of calculating the amount of voltage drop of the pre-correction cell voltage for each cell, if there are two or more cells connected to the same type of conductive member as the conductive member that causes the voltage drop, the amount of voltage drop of the pre-correction cell voltage of one of the two or more cells is calculated, and the calculated amount of voltage drop is adopted as the amount of voltage drop of the pre-correction cell voltage of each of the two or more cells, according to claim 1.

7. In the step of estimating the resistance value of the conductive member, if the estimated temperature of the conductive member is greater than the upper limit of a predetermined temperature range, the estimated result of the resistance value of the conductive member is set to a predetermined maximum value, and if it is less than the lower limit of the temperature range, the estimated result of the resistance value of the conductive member is set to a predetermined minimum value, as described in claim 1.

8. The battery management method according to claim 1, comprising a plurality of the battery modules, wherein the battery has a normal mode and a high-performance mode in which at least one of the regenerative capacity, charging capacity and discharge capacity is higher than that of the normal mode, and in the step of estimating the temperature of the conductive member, if the battery is in high-performance mode, the temperature of the battery module with the highest temperature among the plurality of battery modules is adopted as the module temperature used to estimate the temperature of the conductive member.

9. The battery management method according to claim 1, wherein the conductive member comprises a first conductive member that electrically connects a plurality of cells within the same battery module, and a second conductive member that electrically connects cells within different battery modules.

10. A battery management method for controlling the charging and discharging of a battery having a battery module having a plurality of electrically connected series cells, comprising: a step of obtaining the temperature of conductive members from a temperature detection unit that detects the temperature of conductive members electrically connecting the cells; a step of referring to correspondence relationship information that shows a predetermined correspondence relationship between the temperature of the conductive member and the resistance value of the conductive member, and estimating the resistance value of the conductive member corresponding to the obtained temperature of the conductive member for each of the conductive members; a step of obtaining the pre-correction cell voltage from a voltage detection unit that detects the pre-correction cell voltage, which is the voltage difference between a predetermined location of the conductive member connected to the positive electrode of the cell and a predetermined location of the conductive member connected to the negative electrode of the cell, for each cell; a step of calculating the amount of voltage drop due to the resistance value of the conductive member based on the estimated resistance value of the conductive member that causes a voltage drop in the pre-correction cell voltage of the cell, and the battery current value, which is the current value of the current flowing through the battery, and correcting the pre-correction cell voltage obtained from the voltage detection unit based on the calculated amount of voltage drop; A battery management method comprising the steps of controlling the charging and discharging of the battery based on the corrected cell voltage, which is the corrected cell voltage before correction.

11. A battery management system for controlling the charging and discharging of a battery having a battery module having a plurality of electrically connected series cells, comprising: a temperature detection unit for detecting the module temperature, which is the temperature of the battery module; a current detection unit for detecting the battery current value, which is the current value of the current flowing through the battery; a temperature estimation unit for estimating the temperature of conductive members based on the module temperature detected by the temperature detection unit, the battery current value detected by the current detection unit, and the material properties of conductive members electrically connecting the cells; a storage unit for storing correspondence relationship information that shows a predetermined correspondence relationship between the temperature of the conductive member and the resistance value of the conductive member; a resistance estimation unit for each of the conductive members for estimating the resistance value of the conductive member corresponding to the temperature of the conductive member estimated by the temperature estimation unit, by referring to the correspondence relationship information stored in the storage unit; and a voltage detection unit for detecting the uncorrected cell voltage, which is the voltage difference between a predetermined location of the conductive member connected to the positive electrode of the cell and a predetermined location of the conductive member connected to the negative electrode of the cell. A battery management system comprising: a voltage drop calculation unit that calculates the amount of voltage drop due to the resistance of the conductive member for each cell, based on the resistance value of the conductive member that causes a voltage drop in the pre-correction cell voltage of the cell, which is estimated by the resistance estimation unit, and the battery current value detected by the current detection unit; a correction unit that corrects the pre-correction cell voltage detected by the voltage detection unit for each cell, based on the voltage drop calculated by the voltage drop calculation unit; and a control unit that controls the charging and discharging of the battery based on the corrected cell voltage, which is the pre-correction cell voltage corrected by the correction unit.

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