Battery control device

Abstract

A battery control device includes a controller configured to control charging and discharging of a battery. During a usage period of the battery, the controller is configured to: estimate a state of health of the battery to obtain an estimated state of health; obtain a deteriorated charging state corresponding to the estimated state of health according to relationship information indicating a relationship between a deteriorated state of health of the battery and a deteriorated charging state of the battery; and adjust a charging state of the battery to the deteriorated charging state.

Description

Technical Field

[0001] The present disclosure relates to a battery control device. Background Art

[0002] As a control device for an in-vehicle battery, a control device is known in which by setting a target upper limit value of the remaining battery capacity during vehicle travel and setting a target upper limit value of the remaining battery capacity during vehicle parking, the remaining battery capacity can be controlled within a range that can prevent the progress of deterioration, and the capacity of the battery can be used in a wide range, thereby sufficiently ensuring the driving performance of the vehicle during vehicle travel (for example, refer to Patent Document 1). In the control device described in Patent Document 1, the target upper limit value of the remaining battery capacity is set according to the parking time of the vehicle.

[0003] Patent Document 1: JP-A-2013-074706 Summary of the Invention

[0004] In the control device described in Patent Document 1, when the parking time of the vehicle is within one day, the target upper limit value of the remaining battery capacity is set to 70% of the full battery charge, and when the parking time of the vehicle is two days or longer and less than three days, the target upper limit value of the remaining battery capacity is set to 50% to 60% of the full battery charge. That is, as the parking time of the vehicle becomes longer, the target upper limit value of the remaining battery capacity is set lower. However, in the case of a lithium-ion battery, since the rated capacity decreases with deterioration, it is necessary to set a high charging rate according to the deterioration to ensure the same output.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a battery control device capable of preventing battery deterioration and ensuring the required output of the battery.

[0006] The present disclosure provides a battery control device including: a controller configured to control charging and discharging of a battery, wherein during a usage period of the battery, the controller is configured to: estimate a state of health of the battery to obtain an estimated state of health; obtain a deteriorated charging state corresponding to the estimated state of health according to relationship information indicating a relationship between a state of health after battery deterioration and a charging state after battery deterioration; and adjust a charging state of the battery to the deteriorated charging state.

[0007] According to the present disclosure, by setting the SOC of the battery according to the SOH, battery deterioration can be prevented and the required output of the battery can be ensured. Brief Description of the Drawings

[0008] Figure 1 is a schematic diagram showing a battery control device according to an embodiment of the present disclosure.

[0009] Figure 2 is a schematic diagram showing a battery control device according to another embodiment of the present disclosure.

[0010] Figure 3 is showing Figure 2 a schematic diagram of a degradation coefficient table of the battery control device shown.

[0011] Figure 4 is showing the Figure 2 flowchart of the process executed by the MCU shown. Detailed Description

[0012] Hereinafter, the present disclosure will be described according to preferred embodiments. The present disclosure is not limited to the embodiments to be described below and can be appropriately changed without departing from the scope of the present disclosure. Although some configurations are not shown or described in the embodiments to be described below, known or well-known technologies are appropriately applied to the details of the omitted technologies within the range where there is no contradiction with the content to be described below.

[0013] Figure 1 is a schematic diagram showing a battery control device 10 according to an embodiment of the present disclosure. As shown in this figure, the battery control device 10 is a control device that controls the charging and discharging of the in-vehicle battery 1, and particularly adjusts the SOC (State Of Charge indicating the charging rate or charging state) of the battery 1 during storage.

[0014] The vehicle equipped with the battery control device 10 is a hybrid vehicle or an electric vehicle. The battery 1 is provided as a secondary power source, and the high-voltage power source 2 is provided as a main power source for supplying power to the motor. The battery 1 of the present embodiment is a lithium-ion battery containing manganese as a positive electrode active material and supplies power to the in-vehicle auxiliary device (electrical component) 4. The auxiliary device 4 is an example of a load.

[0015] The power source 2 and the battery 1 are connected by a power line 5. The power line 5 is provided with a switch 3, a DC / DC converter (not shown), etc. When the switch 3 is turned on / off by the battery control device 10, the charging time of the battery 1 is adjusted, and the SOC of the battery 1 is adjusted.

[0016] The battery control device 10 includes a control board 12 on which a microcontroller unit (MCU) 11 is mounted. The MCU 11 is an example of a controller. The MCU 11 stores an SOH estimation logic 111 for estimating the state of health (SOH) of the battery 1, SOH-SOC related information 112, and a control logic 113. The SOH-SOC related information 112 is information about the correlation between the SOH of the battery 1 and the SOC during the storage period of the battery 1 (after deterioration). The control logic 113 controls the charging and discharging of the battery 1. The SOH-SOC related information 112 is an example of related information. For example, information such as the open-circuit voltage, output voltage, output current, internal resistance of the battery 1, and the ambient temperature of the storage battery 1 is input to the MCU 11. The internal resistance of the battery 1 can be calculated by the MCU 11. The MCU 11 may include a processor and a memory storing instructions, which when executed by the processor, cause the processor to perform operations through at least one of the SOH estimation logic 111, the SOH-SOC related information 112, and the control logic 113. The SOH-SOC related information 112 may be stored in the memory or may be stored in another storage device.

[0017] The SOH estimation logic 111 of the MCU 11 estimates (calculates) the SOH of the battery 1 based on the open-circuit voltage, output voltage, output current, internal resistance, etc. of the battery 1. As a method for estimating the SOH, various known methods for estimating the SOH by using the time change of the SOC or / and the time increase of the internal resistance can be used. Examples of the method for estimating the SOH include a method based on a charge and discharge test, a method based on a current integration method, a method based on an open-circuit voltage measurement, a method based on a terminal voltage measurement, a method based on a model (the above are methods using the time change of the SOC), a method based on an AC impedance measurement, a method using a model-based adaptive digital filter, a method based on linear regression from the I-V characteristic (the slope of the straight line of the current-voltage characteristic), a method based on a step response (a method for estimating by using the time increase of the internal resistance), etc.

[0018] The SOH-SOC related information 112 includes SOCinitial, which is the SOC of the battery 1 in the initial state (i.e., the SOH is 100%). SOCinitial is calculated by the following formula (1).

[0019] SOCinitial = SOCmin + Derror... (1)

[0020] SOCmin is the lower limit value of the SOC, which is calculated by the following formula (2). Derror is the detection error.

[0021] SOCmin = Cneed / Cfull... (2)

[0022] Cneed is the charging capacity required to satisfy the required output of the battery 1 according to the specifications of the auxiliary device 4 as the power supply destination, and Cfull is the initial full charge capacity of the battery 1. Cneed is an example of a predetermined charging capacity.

[0023] In addition, the SOH-SOC related information 112 includes SOCdet (an example of the SOC after deterioration), which is the SOC of the battery 1 during use (i.e., when the SOH is less than 100%). SOCdet is calculated by the following formula (3).

[0024] SOCdet = Cneed / (Cfull - Cdet)... (3)

[0025] Cdet is the reduction amount of the charging capacity due to deterioration, and is calculated by the following formula (4). Cfull - Cdet corresponds to the full charge capacity of the battery 1 after deterioration.

[0026] Cdet = (1 - SOH) × Cfull... (4)

[0027] During the use of the battery 1, the SOH estimation logic 111 of the MCU 11 periodically (e.g., monthly) estimates the SOH of the battery 1, and the control logic 113 of the MCU 11 calculates SOCdet corresponding to the SOH estimated by the SOH estimation logic 111 through the above formula (3). Then, the control logic 113 adjusts the charging time of the battery 1 through the switch 3 so that the SOC of the battery 1 is SOCdet.

[0028] That is, in the battery control device 10 of the present embodiment, SOCinitial, which is the initial value of the SOC of the battery 1, is set to the value obtained by adding the detection error Derror to SOCmin, which is the minimum value required for the auxiliary machine 4 as the power supply destination. Therefore, the SOC of the battery 1 in the initial state is suppressed to the necessary minimum value. Thus, deterioration of the battery 1 can be prevented, and the required output of the battery 1 for the auxiliary device 4 as the power supply destination can be ensured.

[0029] In addition, in the battery control device 10 of the present embodiment, the SOCdet during the use of the battery 1 is set to a value obtained by dividing the required charge capacity Cneed for the auxiliary machine 4 as the power supply destination by the full charge capacity after deterioration (a value obtained by subtracting the deterioration amount Cdet of the charge capacity from the initial full charge capacity Cfull). Therefore, the SOC of the battery 1 during use is suppressed to the necessary minimum value. Thus, deterioration of the battery 1 is prevented, and the SOC of the battery 1 during use is periodically increased to SOCdet corresponding to the deterioration of the battery 1. Thus, the required output of the battery 1 required for the auxiliary machine 4 as the power supply destination can be ensured.

[0030] Figure 2 FIG. is a schematic diagram showing a battery control device 20 according to another embodiment of the present disclosure. The same reference numerals are given to configurations similar to those of the above embodiment, and the description of the above embodiment is incorporated. As Figure 2 shown, the battery control device 20 includes a control board 22, and an MCU 21 is mounted on the control board 22. The MCU 21 is an example of a controller. The MCU 21 stores the SOH estimation logic 111, battery initial information 212 as information of the battery 1 in the initial state, a deterioration coefficient table 213, and control logic 214. The deterioration coefficient table 213 is an example of related information. In addition, for example, the open circuit voltage, output voltage, output current of the battery 1, the internal resistance of the battery 1, and information storing the ambient temperature of the battery 1 are input to the MCU 21. The internal resistance of the battery 1 can be calculated by the MCU 21. The MCU 21 may include a processor and a memory storing instructions, and when the instructions are executed by the processor, the processor performs operations through at least one of the SOH estimation logic 111, battery initial information 212, deterioration coefficient table 213, and control logic 214. At least one of the battery initial information 212 and the deterioration coefficient table 213 may be stored in the memory or may be stored in another storage device.

[0031] The SOH estimation logic 111 has a function similar to that of the above embodiment. In addition, the battery initial information 212 includes SOCinitial, which is the SOC of the battery 1 in the initial state (i.e., SOH is 100%). SOCinitial is calculated by the above formula (1).

[0032] The deterioration coefficient table 213 indicates the SOH of the battery 1, the SOC during the storage period of the battery 1 (after deterioration), the temperature during the storage period of the battery 1 (hereinafter referred to as storage temperature), and the deterioration coefficient ksn of the battery 1 (see Figure 3) A table of information on the correlation between [the relevant factors]. Details will be described later. The control logic 214 sets the SOC of battery 1 in the initial state (SOH = 100%) to SOCinitial, and after the second day from the start of use, based on the SOH of battery 1 estimated by the SOH estimation logic 111, the obtained average storage temperature, and the degradation coefficient table 213, periodically (e.g., daily) adjusts the SOC of battery 1 during use.

[0033] Here, as described in the explanation later, even when the degradation of battery 1 does not progress, the progress of degradation is rapid at SOC = 100% at 25°C, but is rapid at SOC = 60% and 70% at 60°C. Therefore, in this embodiment, even when the degradation of battery 1 does not progress, when the ambient temperature increases, the progress of degradation of battery 1 is prevented by increasing the SOC of battery 1 from SOCinitial (e.g., 60%) to SOC (e.g., 80%) at high temperatures in the figure.

[0034] Figure 3 is a schematic diagram showing Figure 2 the degradation coefficient table 213 of the battery control device 20 shown. As shown in this figure, the degradation coefficient table 213 is a table indicating the relationship between SOC, storage temperature, and degradation coefficient ksn at a predetermined SOH. The predetermined SOH is set at every 5%, such as 95%, 90%, 85%, etc. That is, multiple degradation coefficient tables 213 are stored in the MCU 21. In each degradation coefficient table 213, SOC is set at every 10%, such as 100%, 90%, 80%, etc., and the storage temperature is set at every 5°C, such as -30°C, …… -5°C, 0°C, 5°C, etc. The degradation coefficient ksn (ks0, ks1, ks2,..., ksn, n is an integer of 0 or greater) is set for each corresponding SOC and storage temperature. For example, when SOC = 100% and the storage temperature is -30°C, the degradation coefficient is ks0, and when SOC = 90% and the storage temperature is 25°C, the degradation coefficient is ks32.

[0035] The degradation coefficient ksn is set based on the results of the storage test of Battery 1. A larger value of the degradation coefficient ksn indicates greater degradation, and a smaller value indicates less degradation. Here, when the SOC and the storage temperature during storage are high, the storage degradation of the lithium-ion battery does not always easily progress, and depending on the battery material, recent research has shown that when the battery is stored at a specific SOC and a specific storage temperature, the storage degradation of the lithium-ion battery easily progresses (JARI Research Journal 20151201, "Calendar Degradation Mechanism of Lithium-ion Batteries with a LiMn2O4 and LiMO2 (M = Co, Ni and Mn) Composite Cathode", Authors: Keisuke ANDO, Tomoyuki MATSUDA, Masao MYOJIN, Daichi IMAMURA). In particular, in the case where manganese is included in the positive electrode active material, it has been found that when the storage temperature is 25 °C, the SOC is 100%, the progress of degradation is the largest, but when the storage temperature is 60 °C, the SOC is 60% and 70%, the progress of degradation is the largest. In addition, it has also been found that in the case where the storage temperature is 60 °C, within the time period from the start of use to 150 days, the SOC is 70%, the progress of degradation is the largest, and after 150 days from the start of use, the SOC is 60%, the progress of degradation is the largest.

[0036] That is to say, it has been found that in a specific lithium-ion battery including manganese in the positive electrode active material, etc., at a specific storage temperature and a specific SOC below 100%, the progress of specific degradation is significant, and the progress of specific degradation exceeds the progress of degradation when the SOC is 100%.

[0037] Therefore, in the degradation coefficient table 213 of the present embodiment, the degradation coefficient ksn increases as the SOC and the storage temperature during storage increase. However, the degradation coefficient ksn corresponding to a specific storage temperature and a specific SOC less than 100% is set to a value greater than the degradation coefficient ksn corresponding to the specific storage temperature and SOC = 100%. For example, in the degradation coefficient table 213 of a specific SOH (corresponding to the SOH from the start of use to the 150th day), the degradation coefficient ksn corresponding to the storage temperature = 60°C and SOC = 70% is set to the maximum value among the degradation coefficients ksn corresponding to the storage temperature = 60°C. Alternatively, in the degradation coefficient table 213 of a specific SOH (corresponding to the SOH after the 150th day from the start of use), the degradation coefficient ksn corresponding to the storage temperature = 60°C and SOC = 60% is set to the maximum value among the degradation coefficients ksn corresponding to the storage temperature = 60°C.

[0038] Figure 4 is a flowchart showing the processing performed by the Figure 2 MCU 21 shown. First, the control logic 214 of the MCU 21 sets the initial value of the SOC of the new battery 1 to SOCinitial and starts the processing. Here, SOCinitial is derived from a table with SOH = 100% and a storage temperature of 25°C. In step S1, the control logic 214 calculates the average value of the storage temperature (ambient temperature) for one day from the start date of use of the new battery 1 and stores this average value in a memory (not shown) associated with the SOC. Next, in step S2, the control logic 214 reads from the memory the average value of the storage temperature for one day and the SOC of the previous day after the second day from the start of using the new battery 1, causes the SOH estimation logic 111 to estimate the current SOH of the battery 1, and extracts from the degradation coefficient table 213 the degradation coefficient ksn corresponding to the average value of the storage temperature for one day and the SOC of the previous day by referring to the degradation coefficient table 213 corresponding to the estimated SOH. For example, when the SOH on the current day is 90%, the average value of the storage temperature on the previous day is 25°C, and the SOC during storage on the previous day is 80%, the degradation coefficient ksn corresponding to SOC = 80% and storage temperature = 25°C is extracted from the degradation coefficient table 213 with SOH = 90%.

[0039] Next, in step S3, the control logic 214 determines whether the degradation coefficient ksn extracted in step S2 is the minimum value among the multiple degradation coefficients corresponding to the storage temperature of the previous day in the degradation coefficient table 213 selected in step S2. When an affirmative determination is made in step S3, the processing proceeds to step S4, and when a negative determination is made in step S3, the processing proceeds to step S5.

[0040] In step S4, the control logic 214 maintains the SOC of battery 1 at the SOC of the previous day. On the other hand, in step S5, the control logic 214 determines whether there is a degradation coefficient ksn in the degradation coefficient table 213 selected in step S2, which is less than the degradation coefficient ksn extracted in step S2, among the multiple degradation coefficients ksn corresponding to the storage temperature of the previous day and the SOC equal to or greater than SOCmin. When an affirmative determination is made in step S5, the process proceeds to step S6, and when a negative determination is made in step S5, the process proceeds to step S4.

[0041] In step S6, the control logic 214 extracts the degradation coefficient ksn whose value is less than the degradation coefficient ksn extracted in step S2, and the control logic 214 extracts the SOC corresponding to the degradation coefficient ksn from the degradation coefficient table 213. Next, in step S7, the control logic 214 sets the SOC of battery 1 to the SOC (SOCdet) extracted in step S6. The above-described process (steps S1 to S7) is repeatedly executed.

[0042] As described above, in the battery control device 20 of the present embodiment, the MCU 21 obtains the degraded SOC (SOCdet) based on the degradation coefficient table 213 indicating the relationship between the predetermined SOH, SOC, storage temperature, and degradation coefficient ksn of the degraded battery 1, and adjusts the SOC of battery 1 to SOCdet. Specifically, the MCU 21 estimates the SOH of battery 1 and obtains the storage temperature of battery 1 during use, obtains one or more degradation coefficients ksn corresponding to the estimated SOH, the obtained storage temperature, and the SOC equal to or greater than SOCmin from the degradation coefficient table 213, and obtains the SOC corresponding to the minimum degradation coefficient ksn among the obtained one or more degradation coefficients ksn as SOCdet. That is, the battery control device 20 of the present embodiment sets the SOC (SOCdet) of battery 1 during storage according to the SOH (usage cycle) and the ambient temperature so that the degradation coefficient ksn is as small as possible. Therefore, the degradation of battery 1 can be effectively prevented, and the required output of battery 1 can be ensured.

[0043] In particular, in the degradation coefficient table 213 of the present embodiment, the degradation coefficient ksn corresponding to the predetermined storage temperature (for example, 60 °C) and the predetermined SOC (for example, 60% or 70%) is set to be greater than the value of the degradation coefficient ksn corresponding to the predetermined storage temperature and the SOC greater than the predetermined SOC (for example, 100%). Therefore, by setting the SOC of battery 1, it is possible to effectively prevent the degradation of battery 1 and extend the life by avoiding the SOC in which the degradation particularly progresses with respect to battery 1 in which the degradation particularly progresses under the predetermined storage temperature and the predetermined SOC.

[0044] Although the present disclosure has been described based on the embodiments, the present disclosure is not limited to the above embodiments. Without departing from the scope of the present disclosure, the present disclosure can be appropriately modified, or known and publicly known technologies can be appropriately combined.

[0045] For example, in the above embodiment, although the storage temperature is the average temperature of the previous day and the ambient temperature, other measured values such as the median of the temperature of the battery 1 itself and the ambient temperature of the previous day can also be used as the storage temperature. In addition, in the above embodiment, the initial SOC of the battery 1 is set to SOCinitial less than 100%, but the initial SOC of the battery 1 can be set to 100%.

[0046] In addition, in the above embodiment, the present disclosure is described by taking the battery 1 that supplies power to the in-vehicle auxiliary device 4 as an example, and the battery of the present disclosure can also be applied to a power battery pack or a 12V main battery. In addition, in the above embodiment, the present disclosure is described by taking the battery 1 as an example. The battery 1 is a lithium-ion battery containing manganese as a positive electrode active material, but manganese is an example, and the present disclosure can be applied to any battery having a specific SOC in which the progress of specific deterioration is significant.

[0047] As described above, the battery control devices 10; 20 include controllers 11; 21 configured to control the charging and discharging of the battery 1. During the use of the battery 1, the controllers 11; 21 are configured to: estimate the state of health of the battery 1 to obtain an estimated state of health; obtain a deteriorated charging state corresponding to the estimated state of health according to the relationship information 112; 213 indicating the relationship between the state of health of the battery 1 after deterioration and the charging state of the battery 1 after deterioration; and adjust the charging state of the battery 1 to the deteriorated charging state.

[0048] In the battery control device 10, the battery 1 is configured to supply power to the load 4, and the deteriorated charging state is obtained by dividing a predetermined charging capacity by the fully charged capacity of the battery 1 after deterioration, and the predetermined charging capacity is the charging capacity of the battery 1 that satisfies the output required by the load 4.

[0049] In the battery control device 20, the relationship information 213 includes a table 213 indicating the relationship between the state of health of the battery 1 after deterioration, the charging state of the battery 1 after deterioration, the storage temperature, and the deterioration coefficient. During the use period of the battery 1, the controller 21 is configured to: obtain the estimated state of health of the battery 1 and obtain the storage temperature of the battery 1; obtain one or more deterioration coefficients corresponding to the estimated state of health, the obtained storage temperature, and a charging state equal to or greater than a predetermined lower limit value from the table 213; and obtain the charging state corresponding to the minimum deterioration coefficient among the one or more deterioration coefficients as the deteriorated charging state.

[0050] In the battery control device 20, in Table 213, the degradation coefficient corresponding to a predetermined storage temperature and a predetermined charge state is set to a value greater than the degradation coefficient corresponding to the predetermined storage temperature and a charge state greater than the predetermined charge state.

Claims

1. A battery control device, comprising: A controller configured to control charging and discharging of a battery, wherein, during a usage period of the battery, the controller is configured to: Estimate a state of health of the battery to obtain an estimated state of health; Obtain a deteriorated charging state corresponding to the estimated state of health according to relationship information indicating a relationship between a deteriorated state of health of the battery and a deteriorated charging state of the battery; and Adjust a charging state of the battery to the deteriorated charging state, wherein the deteriorated charging state is a charging state of the battery during use, wherein the relationship information includes a table indicating a relationship between a deteriorated state of health of the battery, a deteriorated charging state of the battery, a storage temperature, and a deterioration coefficient, and wherein, during the usage period of the battery, the controller is configured to: Obtain the estimated state of health of the battery and obtain the storage temperature of the battery; Obtain one or more deterioration coefficients corresponding to the estimated state of health, the obtained storage temperature, and a charging state equal to or greater than a predetermined lower limit value from the table; and Obtain a charging state corresponding to the minimum deterioration coefficient among the one or more deterioration coefficients as the deteriorated charging state, wherein the predetermined lower limit value is calculated by dividing a charging capacity required to meet a required output of the battery according to specifications of a load by an initial fully charged capacity of the battery.

2. The battery control device according to claim 1, Among them, In the table, a deterioration coefficient corresponding to a predetermined storage temperature and a predetermined charging state is set to a value greater than a deterioration coefficient corresponding to the predetermined storage temperature and a charging state greater than the predetermined charging state.

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