Charging control system, charging control method, charging control program, and recording medium on which charging control program is recorded

Abstract

In a charge control system, an acquisition unit acquires battery data including at least one of a current flowing through a battery and a temperature of the battery when the battery is charged. The detection unit detects an abnormal phenomenon of the battery on the basis of at least one of the behavior of the current and the behavior of the temperature when the battery is charged. When an abnormal phenomenon of the battery is detected, the charging current changing unit changes the current rate at the time of charging the battery next time to alpha < 0 lt; [alpha] [lt]; 1 is greater than a multiplied value.

Description

Technical Field

[0001] The present disclosure relates to a charging control system, a charging control method, and a charging control program for managing a current rate when charging a battery pack. Background Art

[0002] In recent years, lithium-ion batteries have been used for a variety of purposes. For lithium-ion batteries, most of the following controls are performed: if an abnormality caused by lithium precipitation is detected, the use of lithium-ion battery cells or battery packs (including multiple lithium battery cells) is prohibited. Unsafe incidents such as fires can be prevented by prohibiting the use of cells or packs. For example, Patent Document 1 discloses a control method for judging a battery as non-rechargeable and stopping charging when the detected battery voltage is less than a first voltage.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-254215 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] However, the method of using a threshold value for abnormality determination to determine whether a battery has an abnormality and prohibiting the use of the battery when an abnormality is detected has the following problems. When the threshold value for abnormality determination is set to a relaxed value, the battery is still used even if a slight abnormality occurs, and lithium deposition is sometimes accelerated during this period, shortening the life of the battery. On the contrary, when the threshold value for abnormality determination is set to a strict value, even a battery that can still be safely used according to the usage method may not be used, thereby reducing the cost-effectiveness of the battery as a product.

[0008] The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a technology for suppressing a reduction in cost-effectiveness of a battery while ensuring safety.

[0009] In order to solve the above-mentioned problem, a charging control system of a certain embodiment of the present invention comprises: an acquisition unit, which acquires battery data, wherein the battery data includes at least one of the current flowing through the battery when charging the battery and the temperature of the battery; a detection unit, which detects abnormality of the battery based on at least one of the behavior of the current and the behavior of the temperature when charging the battery; and a charging current change unit, which, when detecting abnormality of the battery, changes the current rate when charging the battery next time to a value of α times, wherein 0<α<1.

[0010] Furthermore, arbitrary combinations of the above-described constituent elements and modes in which expressions of the present disclosure are converted between devices, systems, methods, computer programs, recording media, and the like are also applicable as modes of the present disclosure.

[0011] According to the present disclosure, it is possible to suppress a reduction in cost effectiveness of a battery while ensuring safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a diagram showing a schematic configuration of a battery exchange station using the charging control system according to the embodiment.

[0013] Figure 2 It is a diagram showing a configuration example of a charging control system according to an embodiment.

[0014] Figure 3 It is a diagram showing an example of transition of the voltage, current, and temperature of a cell in which an internal short circuit event occurred during CCCV charging.

[0015] Figure 4 1 is a diagram showing an equivalent circuit model of a single body in which phenomenon 1 occurs.

[0016] Figure 5 This is a diagram showing a negative electrode model for explaining Phenomenon 3 and Phenomenon 4.

[0017] Figure 6 1 is a diagram showing an equivalent circuit model of a single body after Phenomenon 4 occurs.

[0018] Figure 7 1 is a diagram showing an equivalent circuit model of a single body after the occurrence of phenomenon 5.

[0019] Figure 8 This is a diagram showing an example of the relationship between the positive electrode potential and the negative electrode potential of a cell and the SOC.

[0020] Fig. 9 This is a diagram showing a single body model for explaining Phenomenon 7 to Phenomenon 10.

[0021] Fig.10 : is a flowchart showing a specific example of the current rate update process performed by the charging control system according to the embodiment.

[0022] Fig.11 This is a flowchart showing a specific example of a process for updating a voltage value used during CV charging performed by the charging control system according to the embodiment. DETAILED DESCRIPTION

[0023] Figure 11 is a diagram showing a schematic structure of a battery replacement station using a charging control system 10 according to an embodiment. The battery replacement station is set up at a business location of a delivery operator or a taxi operator, for example. The operator manages and operates a plurality of electric vehicles 1, a plurality of battery packs 2, and a plurality of chargers 3 at the business location. The plurality of battery packs 2 are replaceable battery packs that can be loaded and unloaded, and a greater number than the number of electric vehicles 1 is prepared.

[0024] The battery pack 2 is installed on the bottom surface of the electric vehicle 1. When the electric vehicle 1 is parked at a specified position on the replacement table, a replacement device (not shown) provided under the replacement table removes the used battery pack 2 from the bottom surface of the electric vehicle 1 and installs the charged battery pack 2. A belt conveyor for conveying the battery pack 2 is provided under the replacement table. The used battery pack 2 is conveyed to the position of the charger 3 by the belt conveyor. The charged battery pack 2 charged by the charger 3 is conveyed to the position of each replacement table by the belt conveyor. The electric vehicle 1 can usually replace the battery pack 2 in about 5 minutes, and can resume driving in the same amount of time as the refueling time of a gasoline vehicle.

[0025] Each charger 3 has at least one charging slot, and when the battery pack 2 is installed in the charging slot, the battery pack 2 is charged. In addition, the charger 3 and the battery pack 2 can also be connected via a charging cable.

[0026] The battery pack 2 includes a plurality of cells and a battery management unit (BMU). In the battery pack 2, a plurality of cells are connected in series. Alternatively, a plurality of parallel cell blocks formed by connecting a plurality of cells in parallel may be connected in series. As the cells, lithium-ion battery cells, nickel-metal hydride battery cells, lead-acid battery cells, etc. may be used. Below, in this specification, an example of using a lithium-ion battery cell (nominal voltage: 3.6V-3.7V) is assumed. The number of cells or parallel cell blocks connected in series is determined according to the driving voltage of the motor mounted in the electric vehicle 1.

[0027] The battery management unit monitors and measures the voltage, current, temperature, and SOC (State Of Charge) of the multiple cells or multiple parallel cell blocks included in the battery pack 2. A shunt resistor is connected in series with the multiple cells or multiple parallel cell blocks connected in series. The shunt resistor functions as a current detection element. In addition, a Hall element can also be used instead of the shunt resistor. A plurality of temperature sensors (such as thermistors) for detecting the temperature of the multiple cells or multiple parallel cell blocks are provided in the battery pack 2. For example, one temperature sensor can be provided for 6 to 8 cells or parallel cell blocks.

[0028] The battery management unit estimates the SOC by combining the OCV (Open Circuit Voltage) method and the current accumulation method. The OCV method is a method for estimating the SOC based on the measured OCV of each cell and the SOC-OCV curve of the cell. The current accumulation method is a method for estimating the SOC based on the OCV of each cell at the start of charge and discharge and the cumulative value of the measured current. The current accumulation method accumulates the measurement error of the current as the charge and discharge time becomes longer. Therefore, it is preferred to use the SOC estimated by the OCV method to correct the SOC estimated by the current accumulation method.

[0029] The battery management unit samples the voltage, current, temperature, and SOC of a plurality of cells or a plurality of parallel cell blocks periodically (for example, at intervals of 10 seconds) and accumulates them as battery data of the battery pack 2. In addition, the battery management unit may also record the highest temperature and the lowest temperature among a plurality of temperatures detected by a plurality of temperature sensors provided in the battery pack 2.

[0030] The charger 3 is connected to a commercial power system (not shown) to charge the battery pack 2. Generally, the battery pack 2 is charged with AC power in the case of normal charging, and charged with DC power in the case of rapid charging. When charging with AC power (for example, single-phase 100V / 200V), the AC / DC converter in the battery pack 2 converts the AC power into DC power. When charging with DC power, the charger 3 generates DC power by full-wave rectifying the AC power supplied from the commercial power system and smoothing it with a filter.

[0031] As fast charging standards, for example, CHAdeMO (registered trademark), ChaoJi, GB / T, and Combo (Combined Charging System) can be used. In CHAdeMO2.0, the maximum output (specification) is specified as 1000V×400A=400kW. In CHAdeMO3.0, the maximum output (specification) is specified as 1500V×600A=900kW. In ChaoJi, the maximum output (specification) is specified as 1500V×600A=900kW. In GB / T, the maximum output (specification) is specified as 750V×250A=185kW. In Combo, the maximum output (specification) is specified as 900V×400A=350kW. In CHAdeMO, ChaoJi, and GB / T, CAN (Controller Area Network) is used as the communication method. In Combo, PLC (Power Line Communication) is adopted as the communication method.

[0032] The charger 3 supporting fast charging has a DC / DC converter. During fast charging, the DC / DC converter of the charger 3 controls the charging current or charging voltage during charging. In the present embodiment, the charger 3 charges the battery pack 2 in a constant current constant voltage (hereinafter referred to as CCCV) method. The CCCV method is a method in which CC charging of the battery pack 2 is started at a set current rate, and when the voltage of the battery pack 2 reaches a set target voltage, the control is switched to CV charging of the battery pack 2 at the target voltage. In the present embodiment, the current rate used during CC charging and the voltage value used during CV charging are specified by the charging control system 10.

[0033] In the case of normal charging, the AC / DC converter or DC / DC converter of the battery pack 2 controls the charging current or charging voltage during charging. In this case, the current rate used during CC charging and the voltage value used during CV charging are notified from the charging control system 10 to the battery management unit of the battery pack 2 via the charger 3. The battery management unit of the battery pack 2 transmits the battery data during charging to the charger 3. The charger 3 transmits the received battery data to the charging control system 10.

[0034] The charging control system 10 is a system for controlling the charging of multiple battery packs 2 managed by an operator operating a battery replacement station. The charging control system 10 can also be constructed on a server or PC set up in a business location where a battery replacement station is set up. In addition, the charging control system 10 can also be constructed on a self-owned server set up in a self-owned company facility or data center of an operator that provides battery analysis services to multiple operators. In addition, the charging control system 10 can also be constructed on a cloud server used by a distribution operator, a taxi operator, or a battery analysis operator based on a cloud service agreement. In addition, the charging control system 10 can also be constructed on multiple servers dispersed in multiple locations (data centers, self-owned company facilities). The multiple servers can also be any combination of a combination of multiple self-owned company servers, a combination of multiple cloud servers, and a combination of self-owned company servers and cloud servers.

[0035] The charging control system 10 is connected to a plurality of chargers 3 installed at a battery exchange station via a network 5 (eg, wired / wireless LAN, Internet, dedicated line, VPN (Virtual Private Network) etc.) Each charger 3 transmits battery data acquired from the battery pack 2 to the charging control system 10 via the network 5 .

[0036] Figure 21 is a diagram showing a configuration example of a charging control system 10 according to an embodiment. The charging control system 10 includes a processing unit 11, a storage unit 12, and a communication unit 13. The communication unit 13 is a communication interface (eg, NIC: Network Interface Card) for connecting to the network 5 in a wired or wireless manner.

[0037] The processing unit 11 includes an acquisition unit 111, a detection unit 112, a charging current change unit 113 and a charging indication unit 114. The functions of the processing unit 11 can be realized by the collaboration of hardware resources and software resources, or only by hardware resources. As hardware resources, CPU, ROM, RAM, GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), and other LSI can be used. As software resources, programs such as operating systems and application programs can be used. The program is pre-recorded in the memory of the storage unit 12 here, but it can also be provided through an electrical communication line such as the Internet, or recorded on a (non-transitory) recording medium such as a memory card.

[0038] The storage unit 12 includes a nonvolatile recording medium such as an HDD or an SSD, and stores various data. The storage unit 12 includes a battery data storage unit 121 and a charging current and voltage storage unit 122 .

[0039] The acquisition unit 111 acquires the battery data of each battery pack 2 from each charger 3 and stores the acquired data in the battery data holding unit 121 .

[0040] The charging current and voltage holding unit 122 holds the current rate used during CC charging and the voltage value used during CV charging when charging in the CCCV method for each battery pack 2 managed by the operator. The battery pack 2 is managed by ID. For the default current rate used during CC charging and the default voltage value used during CV charging, the recommended value announced by the battery manufacturer for each model may be used, or the value determined by the operator may be used.

[0041] The current rate used during CC charging is determined by taking into account the balance between charging time and battery degradation within the range of the rated current of the battery pack 2. In the case of shortening the charging time, the current rate needs to be increased, which increases the burden on the battery. Conversely, in the case where the charging time can be long, the current rate can be reduced, which reduces the burden on the battery.

[0042] The voltage value used during CV charging is determined within the range of the rated voltage of the battery pack 2 according to the capacity of the battery pack 2. Alternatively, the voltage value used during CV charging may be reduced as the SOH (State Of Health) of the battery decreases.

[0043] The acquisition unit 111 acquires the battery data when CCCV charging is performed on the battery pack 2 from the charger 3. The acquisition unit 111 may acquire the battery data during CCCV charging from the charger 3 in real time, or acquire the battery data during CCCV charging after charging is completed. The acquired battery data includes the ID of the battery pack 2 and at least one of the current flowing through the battery pack 2 and the temperature of the battery pack 2. The acquisition unit 111 stores the acquired battery data in the battery data storage unit 121.

[0044] The detection unit 112 detects abnormality of a cell in the battery pack 2 based on at least one of the behavior of the current and the behavior of the temperature of the battery pack 2 during the CV charging period when the battery pack 2 is CCCV charged. As the temperature, for example, the highest temperature detected by a plurality of temperature sensors provided in the battery pack 2 may be used.

[0045] In this embodiment, attention is paid to a micro internal short circuit event caused by lithium deposition as an abnormal phenomenon of a cell in the battery pack 2. When an internal short circuit event occurs, the current increases or the current decreases less during CV charging, and the temperature rises rapidly.

[0046] Figure 3 This is a diagram showing an example of the transition of the voltage V, current I, and temperature T of a cell that has an internal short circuit event during CCCV charging. If the cell is in a normal state, the current I gradually decreases during CV charging. In contrast, when an internal short circuit event occurs in the cell during CV charging, the current I increases. At the same time, the temperature T of the cell rises sharply. In addition, Figure 3 The transitions of the voltage V, current I, and temperature T shown are examples, and the degree of change in current or temperature varies depending on the internal state of the cell. For example, there is a case where the current I does not increase but the rate of decrease becomes slow.

[0047] Next, the mechanism of the internal short circuit event is described. When charging and discharging with a short pause time are repeated, the following phenomena 1 to 4 occur. The short pause time is, for example, a pause time of about 20 minutes.

[0048] Figure 4: This is a diagram showing an equivalent circuit model of a single body that produces phenomenon 1. When charging and discharging with short pause times are repeated, the return of the electrolyte slows down and the electrolyte is lacking, thereby increasing the liquid resistance (phenomenon 1). The increase in liquid resistance becomes the main reason for the decrease in current. The increase in liquid resistance causes the negative electrode potential to decrease (phenomenon 2).

[0049] Figure 5 This is a diagram showing a negative electrode model for illustrating phenomena 3 to 4. At the end of charging, the negative electrode potential is lower than the lithium potential, and a small amount of lithium is deposited on the negative electrode (phenomenon 3). The lithium deposited on the negative electrode is inserted into the negative electrode during the pause process, and returns to the positive electrode during the discharge process. Most of the deposited lithium returns to the positive electrode during discharge, but a part remains on the negative electrode. During each charge and discharge, the lithium remaining on the negative electrode reacts with the electrolyte and changes into SEI (Solid Electrolyte Interphase) (phenomenon 4). SEI grows due to the repetition of such a process. The growth of SEI causes the resistance to increase and becomes the main reason for the decrease in current.

[0050] Figure 6 : is a figure which shows the equivalent circuit model of the single body after the occurrence of phenomenon 4. In the single body after the occurrence of phenomenon 4, the SEI resistance of the negative electrode increases.

[0051] The following phenomena 5 and 6 occur due to the long pause time between charge and discharge. The long pause time is, for example, about 1 hour. Due to the long pause time, the electrolyte returns to the positive electrode (phenomenon 5).

[0052] Figure 7 : is a diagram showing an equivalent circuit model of a single cell after occurrence of phenomenon 5. In the single cell after occurrence of phenomenon 5, the liquid resistance of the positive electrode decreases. When the positive electrode potential decreases as the internal resistance of the positive electrode decreases, the negative electrode potential further decreases to maintain the target voltage (e.g., 4.2 V) during CV charging (phenomenon 6).

[0053] Figure 8 It is a diagram showing an example of the relationship between the positive electrode potential and the negative electrode potential of a monomer and the SOC. The horizontal axis represents the SOC, and the vertical axis represents the positive electrode potential and the negative electrode potential. The positive electrode potential increases as the SOC increases, and the negative electrode potential decreases as the SOC increases. As mentioned above, due to the increase in liquid resistance caused by the shortage of electrolyte, the negative electrode potential decreases (phenomenon 2). Due to the decrease in liquid resistance of the positive electrode, the positive electrode potential and the negative electrode potential decrease to the same extent (phenomenon 6). This state is a state in which lithium is easily precipitated, and the current increases.

[0054] Fig. 9This is a diagram showing a single body model for explaining phenomena 7 to 10. Due to charging, the following phenomena 7 to 9 are repeatedly generated, and an internal short circuit event occurs. Since the negative electrode potential is greatly reduced and the current increases, a large amount of lithium is deposited on the SEI (phenomenon 7). More lithium is deposited than in phenomenon 3.

[0055] The positive electrode and the negative electrode are short-circuited due to the deposited lithium, and heat is generated due to the flow of the short-circuit current (phenomenon 8). The lithium in contact with the positive electrode is oxidized and becomes lithium ions. The lithium ions are deposited on the negative electrode, and the short circuit is eliminated (phenomenon 9). If charging is stopped, the lithium deposition stops, and the heat caused by the short circuit stops (phenomenon 10).

[0056] In order to detect the internal short circuit event described above from the outside, it is considered to detect at least one of the increase in current during CV charging and the rapid temperature rise during CV charging. When a small short circuit occurs in a cell, the converter operates to maintain the target voltage for CV charging, so the current increases. In addition, the whole cell is heated uniformly due to the small short circuit.

[0057] The main reasons that hinder the detection of an internal short circuit event are listed below.

[0058] (a) In the case of a slight internal short circuit, the current does not increase, but decreases at a slower rate.

[0059] (b) In the case where CV charging is performed with a total voltage reference, the current does not increase even if an internal short circuit event occurs.

[0060] (c) During the CV charging process, the battery returns to the CC charging process again. In this case, the current increases even if no internal short circuit occurs.

[0061] (d) During CV charging, the current oscillates.

[0062] (e) The battery temperature rises sharply due to heating by an external heat source (eg, a heater).

[0063] (f) The increase in battery temperature is suppressed due to cooling by the cooler.

[0064] Next, a highly reliable detection method of an internal short circuit event is described. The detection unit 112 detects an internal short circuit event by detecting a temperature rise of a cell that exceeds the amount of heat generated by the charging current during CV charging of the battery pack 2. More specifically, the detection unit 112 detects an internal short circuit event of a cell in the battery pack 2 by comparing the ratio of the integrated amount of current flowing through the cell in the battery pack 2 during a certain period to the temperature rise of the cell in the battery pack 2 during a certain period with a predetermined threshold value during CV charging.

[0065] The amount of heat Q generated by the charging current is calculated by the following formula (1).

[0066] Q=I 2 ×R×△t…(Formula 1)

[0067] Q: Heat generation[J]

[0068] Δt: The time required for the temperature rise of ΔT [s]

[0069] I: Average current during Δt [A]

[0070] R: Internal resistance [Ω]

[0071] The calorific value Q of the cell estimated from the temperature measured by the temperature sensor is obtained by the following formula (Formula 2).

[0072] Q=C×△T…(Formula 2)

[0073] Q: Heat generation[J]

[0074] C: Heat capacity of monomer [J / K]

[0075] ΔT: Temperature rise during Δt [℃]

[0076] The detector 112 passes (ΔT / I 2 When the determination score calculated by (xΔt) exceeds a predetermined threshold value, it is determined that an internal short circuit event has occurred in the cell of the battery pack 2. The predetermined threshold value is set in advance based on the results of experiments and simulations.

[0077] When the detector 112 detects an internal short circuit event in a cell in the battery pack 2 during the current CCCV charge, it specifies the SOC of the battery pack 2 at the time of detecting the internal short circuit event. The detector 112 stores the detected SOC in the charging current and voltage holding unit 122 .

[0078] When an internal short circuit event is detected in a single cell in the battery pack 2 during the current CCCV charging, the charging current change unit 113 changes the current rate used during the CC charging period when the battery pack 2 is CCCV charged next time to a value α (0<α<1) times. That is, the charging current change unit 113 reduces the current rate during the CC charging period at the next charging by a certain ratio. A lower limit is set for the current rate. For example, it is set to a range of 0.1 to 0.5 times the preset default current rate. The lower the current rate, the longer the charging time. The operator can set or change the lower limit of the current rate to an arbitrary value in view of the operating conditions of the battery pack 2. The charging current change unit 113 saves the changed current rate in the charging current voltage holding unit 122.

[0079] The changed current rate is used as the current rate after the SOC of the battery pack 2 reaches the SOC at the time point when the internal short circuit event is detected when the battery pack 2 is CCCV charged next time. The default current rate is used before the SOC is reached.

[0080] When no internal short circuit event is detected for a single cell in the battery pack 2 during the current CCCV charging, the charging current changing unit 113 changes the current rate used during the CC charging period when the battery pack 2 is CCCV charged next time to a value of β (1<β<(2-α)) times. That is, the charging current changing unit 113 increases the current rate during the CC charging period at the next charging by a certain ratio. The charging current changing unit 113 increases the current rate when no internal short circuit event is detected at a ratio smaller than the ratio at which the current rate is reduced when an internal short circuit event is detected. The upper limit of the current rate is set to a default current rate. The charging current changing unit 113 saves the changed current rate in the charging current voltage holding unit 122.

[0081] Alternatively, the larger the determination score calculated by the detection unit 112 is than the threshold value, the smaller the ratio α used when reducing the current rate is. For example, in the range of 0.99 to 0.50, the larger the determination score is than the threshold value, the smaller the ratio α used when reducing the current rate is set by the charging current change unit 113. For example, in the range of 0.99 to 0.50, the larger the determination score is than the threshold value, the closer the value of α is to 0.50. The relationship between the determination score and α is defined by a map or a function. The relationship between the determination score and α can be set to be linear or nonlinear. In addition, the relationship between the temperature rise rate and the current rate and α can be defined in advance as a map, and the charging current change unit 113 determines the ratio α based on the temperature rise rate and the current rate and with reference to the map. For example, the higher the temperature rise rate, the smaller the value of α is defined. Similarly, for the ratio β, the relationship between the temperature rise rate and the current rate and β can be defined in advance as a map, and the charging current change unit 113 determines the ratio β based on the temperature rise rate and the current rate and with reference to the map. For example, the lower the temperature rise rate, the larger the value of β is defined.

[0082] The acquisition unit 111 acquires the group ID of the battery pack 2 to be charged from the charger 3 when the charger 3 charges the battery pack 2. The charge instruction unit 114 acquires the charging information of the battery pack 2 to be charged by referring to the charging current and voltage holding unit 122 based on the acquired group ID.

[0083] The charging information includes the default current rate used during CC charging of the battery pack 2 to be charged, the SOC at which the default current rate is switched to the limited current rate, the limited current rate, and the voltage value used during CV charging. The charging instruction unit 114 notifies the charger 3 of the charging instruction including the charging information.

[0084] Fig.10 1 is a flowchart showing a specific example of the current rate update process performed by the charging control system 10 according to the embodiment. The acquisition unit 111 acquires the battery data during CCCV charging from the charger 3 that performs CCCV charging on the battery pack 2 (S10). The detection unit 112 determines whether an internal short circuit event has occurred in a cell in the battery pack 2 during CV charging based on the battery data during CV charging (S11).

[0085] When an internal short circuit event is detected ("Yes" in S11), the detection unit 112 determines the SOC of the battery pack 2 at the time when the internal short circuit event is detected, and stores the SOC in the charging current and voltage holding unit 122 (S12). The charging current changing unit 113 sets the current rate to 0.9 times the current rate, and stores the changed current rate in the charging current and voltage holding unit 122 (S13).

[0086] The charging current changing unit 113 compares the changed current rate with the lower limit value (S14). When the changed current rate is lower than the lower limit value ("Yes" in S14), the charging current changing unit 113 sets the battery pack 2 as the target to be prohibited from charging (S15), and stores the prohibition of charging of the battery pack 2 in the charging current and voltage holding unit 122. After this storage, the current rate update process is terminated. When the changed current rate is not lower than the lower limit value ("No" in S14), the current rate update process is terminated.

[0087] When an internal short circuit event is not detected in step S11 (No in S11), the charging current changing unit 113 changes the current rate to 1.05 times the current rate, and stores the changed current rate in the charging current voltage holding unit 122 (S16).

[0088] The charging current changing unit 113 compares the changed current rate with the default current rate (S17). When the changed current rate is higher than the default current rate ("Yes" in S17), the charging current changing unit 113 changes the current rate to the default current rate and saves the changed current rate in the charging current voltage holding unit 122 (S18). After the saving, the current rate update process is terminated. When the changed current rate is not higher than the default current rate ("No" in S17), the current rate update process is terminated.

[0089] In the above description, the charging control in which the current rate is reduced when an internal short circuit event is detected is described. In this regard, the charging control in which the voltage value used during CV charging is reduced when an internal short circuit event is detected may also be performed.

[0090] Fig.11 1 is a flowchart showing a specific example of the updating process of the voltage value used during the CV charging performed by the charging control system 10 according to the embodiment. The acquisition unit 111 acquires the battery data during CCCV charging from the charger 3 that performs CCCV charging on the battery pack 2 (S20). The detection unit 112 determines whether an internal short circuit event has occurred in a cell in the battery pack 2 during CV charging based on the battery data during CV charging (S21).

[0091] When an internal short circuit event is detected (Yes in S21), the detection unit 112 determines the SOC of the battery pack 2 at the time when the internal short circuit event is detected. The detection unit 112 determines the OCV of the battery pack 2 at the time when the internal short circuit event is detected based on the determined SOC and with reference to the SOC-OCV curve of the battery pack 2 (S22).

[0092] The charging voltage change unit (not shown) changes the voltage value used during CV charging (hereinafter referred to as the target voltage value) to the determined OCV, and stores the changed target voltage value in the charging current voltage holding unit 122. After the storage, the target voltage value update process is terminated.

[0093] If no internal short circuit event is detected in step S21 (No in S21), the charging voltage change unit sets the target voltage value to 1.05 times the target voltage value, and stores the changed target voltage value in the charging current voltage holding unit 122 (S24). In addition, 1.05 times is an example, and the target voltage value may be increased at a ratio other than 1.05 times.

[0094] The charging voltage change unit compares the changed target voltage value with the default target voltage value (S25). When the changed target voltage value is higher than the default target voltage value ("Yes" in S25), the charging voltage change unit changes the target voltage value to the default target voltage value and saves the changed target voltage value in the charging current voltage holding unit 122 (S26). After the saving, the target voltage value update process is terminated. When the changed target voltage value is not higher than the default target voltage value ("No" in S25), the target voltage value update process is terminated.

[0095] In the above description, the detection unit 112 detects an internal short circuit event during CV charging based on whether the ratio of the integrated amount of current flowing through the cells in the battery pack 2 during a certain period to the temperature rise of the cells in the battery pack 2 during a certain period exceeds a threshold value. In this regard, an internal short circuit event may be detected simply as follows.

[0096] The detection unit 112 may also detect an internal short circuit event based on whether the temperature of the cells in the battery pack 2 during CV charging exceeds a threshold value (e.g., 50° C.). In addition, the detection unit 112 may also detect an internal short circuit event based on whether the temperature rise rate of the cells in the battery pack 2 during CV charging exceeds a threshold value. In addition, the detection unit 112 may also detect an internal short circuit event based on whether the current flowing through the cells in the battery pack 2 increases for a period of time or more during CV charging.

[0097] As described above, according to the present embodiment, when an abnormality is detected based on the battery data, the use of the battery pack 2 is not prohibited at all, but the current rate is reduced at a certain rate. As a result, it is possible to suppress the reduction in cost-effectiveness of the battery pack 2 while ensuring safety. Since the battery pack 2 can be used as long as possible while ensuring safety, the replacement cost of the battery pack 2 can be reduced.

[0098] In addition, it is possible to balance safety and product performance by adding control to restore the current rate when no abnormality is detected in the most recent charging. For example, a phenomenon in which the temperature rises sharply due to heat flow from the heater is sometimes mistakenly detected as an abnormality of the cell. In this case, since the cell itself is not abnormal, charging with a reduced current rate will damage product performance. Product performance can be gradually restored by restoring the current rate while confirming safety.

[0099] This embodiment can also cope with abnormalities in which the current or temperature rises suddenly due to reasons other than lithium deposition (for example, mixing of foreign matter).

[0100] Furthermore, the charging control that reduces the current rate is more advantageous in terms of operation cost than the charging control that reduces the target voltage value. Since the charging control that reduces the current rate does not reduce the chargeable capacity, it does not increase the number of charging times.

[0101] The present disclosure has been described above based on the embodiments. It will be understood by those skilled in the art that the embodiments are illustrative only and that various modifications can be obtained for the combination of the components and the processing steps, and such modifications are also within the scope of the present disclosure.

[0102] When the cell is being heated by the heater, it is difficult to determine whether the temperature rise of the cell is caused by the increase in the charging current or the heating by the heater. Therefore, the detection of the internal short circuit event may be stopped during the heating by the heater.

[0103] In the case of an air-cooled battery pack 2, the temperature of a single cell cannot be lowered in a short time. Therefore, in the case of an air-cooled battery pack 2, if there is an unnatural temperature rise during CV charging, the possibility of an internal short circuit event is high. On the other hand, in the case of a liquid-cooled battery pack 2, the temperature rise of a single cell caused by an internal short circuit event is sometimes eliminated by a liquid-cooled cooler. In the case of a liquid-cooled battery pack 2, it is also possible to correct the temperature based on the cooling capacity of the cooler and use the corrected temperature to detect an internal short circuit event.

[0104] In the above embodiment, an internal short circuit event is detected by detecting at least one of an increase in current and a sharp temperature rise during CV charging. In this regard, an internal short circuit event can also be detected by detecting at least one of an increase in current and a sharp temperature rise during low-rate CC charging.

[0105] In the above embodiment, an example is described in which the charging rate of the battery pack 2 is managed in the charging control system 10 connected to the charger 3 via the network 5. In this regard, the charging control system 10 may be embedded in the battery management unit (BMU) in the battery pack 2. In addition, the charging control system 10 may be embedded in the charger 3.

[0106] In addition, the charging control system 10 involved in the present disclosure is not limited to the management of the charging rate of the battery pack 2 mounted in the electric vehicle 1. For example, it can also be applied to the management of the charging rate of the battery pack mounted in the electric ship, multi-rotor aircraft (drone), electric motorcycle, electric bicycle, stationary power storage system, smart phone, tablet computer, notebook computer, etc.

[0107] In addition, the implementation mode may also be determined by the following items.

[0108] [Project 1]

[0109] A charging control system (10), characterized by comprising:

[0110] An acquisition unit (111) that acquires battery data, the battery data including at least one of a current flowing through the battery (2) when the battery (2) is charged and a temperature of the battery (2);

[0111] a detection unit (112) for detecting an abnormality of the battery (2) based on at least one of the behavior of the current and the behavior of the temperature when the battery (2) is charged; and

[0112] The charging current changing unit (113) changes the current rate of the next charging of the battery (2) to a value α times when an abnormality of the battery (2) is detected, wherein 0<α<1.

[0113] As a result, it is possible to suppress a reduction in cost effectiveness of the battery pack (2) while ensuring safety.

[0114] [Project 2]

[0115] The charging control system (10) according to item 1, wherein:

[0116] When no abnormality of the battery (2) is detected during this charging, the charging current changing unit (113) changes the current rate when the battery (2) is charged next time to a value β times, where 1<β<(2-α).

[0117] This can eliminate unnecessary extension of charging time.

[0118] [Item 3]

[0119] The charging control system (10) according to item 1 is characterized in that:

[0120] The detection unit (112) determines the state of charge (SOC) of the battery (2) at the time when the abnormality of the battery (2) is detected,

[0121] The changed current rate is used as the current rate after the SOC of the battery (2) reaches the SOC at the time point when the abnormal phenomenon is detected when the battery (2) is charged next time.

[0122] This can minimize the extension of the charging time.

[0123] [Item 4]

[0124] The charging control system (10) according to item 1, wherein:

[0125] During charging, the detection unit (112) compares the integrated amount of current flowing through the battery (2) during a certain period and the ratio of the temperature rise of the battery (2) during the certain period with a predetermined threshold value to detect abnormality of the battery (2).

[0126] As a result, abnormality of the battery (2) caused by an increase in charging current can be detected with high accuracy.

[0127] [Item 5]

[0128] The charging control system (10) according to item 4, wherein:

[0129] The charging current changing unit (113) makes the α smaller as the ratio is larger than the threshold value.

[0130] Thereby, the reduction rate of the current rate can be optimized.

[0131] [Item 6]

[0132] The charging control system (10) according to item 4, wherein:

[0133] The charging current changing unit (113) sets the β based on the temperature increase rate of the battery (2) and the current current rate.

[0134] Thereby, the rate of increase of the current rate can be optimized.

[0135] [Item 7]

[0136] A charging control method, characterized by comprising the following steps:

[0137] Acquiring battery data, the battery data comprising at least one of a current flowing through the battery (2) when the battery (2) is charged and a temperature of the battery (2);

[0138] detecting an abnormality of the battery (2) based on at least one of the behavior of the current and the behavior of the temperature when the battery (2) is charged; and

[0139] When an abnormality of the battery (2) is detected, the current rate when the battery (2) is charged next time is changed to a value of α times, where 0<α<1.

[0140] As a result, it is possible to suppress a reduction in cost effectiveness of the battery pack (2) while ensuring safety.

[0141] [Item 8]

[0142] A charging control program, characterized in that it causes a computer to execute the following processing:

[0143] Acquiring battery data, the battery data comprising at least one of a current flowing through the battery (2) when the battery (2) is charged and a temperature of the battery (2);

[0144] detecting an abnormality of the battery (2) based on at least one of the behavior of the current and the behavior of the temperature when the battery (2) is charged; and

[0145] When an abnormality of the battery (2) is detected, the current rate when the battery (2) is charged next time is changed to a value of α times, where 0<α<1.

[0146] As a result, it is possible to suppress a reduction in cost effectiveness of the battery pack (2) while ensuring safety.

[0147] Description of Reference Numerals

[0148] 1: Electric vehicle; 2: Battery pack; 3: Charger; 5: Network; 10: Charging control system; 11: Processing unit; 111: Acquisition unit; 112: Detection unit; 113: Charging current change unit; 114: Charging indication unit; 12: Storage unit; 121: Battery data holding unit; 122: Charging current and voltage holding unit; 13: Communication unit.

Claims

1. A charging control system, characterized in that: have: an acquisition unit configured to acquire battery data, the battery data including at least one of a current flowing through the battery when the battery is charged and a temperature of the battery; a detection unit configured to detect an abnormality of the battery based on at least one of a behavior of the current and a behavior of the temperature when the battery is charged; as well as The charging current changing unit changes the current rate of the next charging of the battery to a value of α times when an abnormality of the battery is detected, wherein 0<α<1.

2. The charging control system according to claim 1, wherein: When no abnormality of the battery is detected during the current charging, the charging current changing unit changes the current rate when the battery is charged next time to a value of β times, where 1<β<(2-α).

3. The charging control system according to claim 1, characterized in that: The detection unit determines the state of charge (SOC) of the battery at the time when the abnormality of the battery is detected, The changed current rate is used as the current rate after the SOC of the battery reaches the SOC at the time point when the abnormal phenomenon is detected when the battery is charged next time.

4. The charging control system according to claim 1, wherein: The detection unit detects abnormality of the battery by comparing the integrated amount of current flowing through the battery during a certain period and the ratio of the temperature rise of the battery during the certain period with a predetermined threshold value during charging.

5. The charging control system according to claim 4, wherein: The charging current changing unit reduces the α as the ratio is larger than the threshold value.

6. The charging control system according to claim 2, wherein: The charging current changing unit sets the β based on the temperature increase rate of the battery and a current current rate.

7. A charging control method, characterized in that: The following steps are involved: acquiring battery data, the battery data including at least one of a current flowing through the battery when the battery is charged and a temperature of the battery; detecting an abnormality of the battery based on at least one of a behavior of the current and a behavior of the temperature when the battery is charged; as well as When an abnormality of the battery is detected, the current rate when the battery is charged next time is changed to a value of α times, where 0<α<1.

8. A charging control program, characterized in that: Causes the computer to perform the following processing: acquiring battery data, the battery data including at least one of a current flowing through the battery when the battery is charged and a temperature of the battery; detecting an abnormality of the battery based on at least one of a behavior of the current and a behavior of the temperature when the battery is charged; as well as When an abnormality of the battery is detected, the current rate when the battery is charged next time is changed to a value of α times, where 0<α<1. 9 . A non-transitory recording medium having the charging control program according to claim 8 recorded thereon.

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