Lithium ion secondary battery control device and control method thereof

Abstract

A control device for controlling a lithium-ion secondary battery comprises a control unit, which detects the charging current when the lithium-ion secondary battery is charged at a constant voltage, stops charging the lithium-ion secondary battery when the charging current increases by a specified amount within a specified time, and records control information based on the increase in the charging current in a storage unit of the lithium-ion secondary battery.

Description

Technical Field

[0001] The present disclosure relates to a control device for controlling a lithium-ion secondary battery and a control method thereof. Background Art

[0002] Lithium-ion secondary batteries use an electrolyte that converts lithium into an ion state. Lithium has the characteristics of rapid reaction and smoke and fire due to the heat of reaction. Therefore, in the past, temperature control was performed in lithium-ion secondary batteries, and the operation was stopped before smoke or fire was about to occur.

[0003] In Patent Document 1, a temperature measuring device is provided in a lithium-ion secondary battery, and temperature changes are managed using differential values, etc., thereby grasping a small short circuit phenomenon generated inside the battery and determining whether the battery has stopped operating. The small short circuit phenomenon is pointed out to be particularly prone to occur when the lithium-ion secondary battery is overcharged.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 10-92476 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in the conventional technology, the occurrence of smoke and fire in lithium ion secondary batteries is suppressed by capturing the phenomenon just before these phenomena occur. Therefore, even if an abnormality is detected, there is a possibility that sufficient time cannot be secured and no response can be taken.

[0009] Furthermore, if an attempt is made to detect the occurrence of an abnormality earlier than before, there is also a problem of false detection in which even a normal lithium ion secondary battery is mistakenly detected as an abnormality.

[0010] The present disclosure aims to detect the occurrence of abnormality in a lithium ion secondary battery more accurately than before by newly discovering a sign that the lithium ion secondary battery is in an abnormal state such as smoking or catching fire.

[0011] Means for solving problems

[0012] The control device disclosed in the present invention is a control device for controlling a lithium-ion secondary battery, and is equipped with a control unit, which detects the charging current when the lithium-ion secondary battery is charged at a constant voltage, stops charging the lithium-ion secondary battery when the charging current increases by a specified amount within a specified time, and records control information based on the increase in charging current in a storage unit of the lithium-ion secondary battery.

[0013] The control device disclosed in the present invention is a control device for controlling a lithium-ion secondary battery, and includes a control unit that calculates the temperature of a battery cell constituting the lithium-ion secondary battery and records control information based on the temperature calculation in a storage unit of the lithium-ion secondary battery when the temperature increases by more than a specified amount within a specified period.

[0014] The control device disclosed in the present invention is a control device for controlling a lithium-ion secondary battery, and is provided with a control unit, which detects the voltage of battery cells constituting the lithium-ion secondary battery after the lithium-ion secondary battery is charged to a voltage above a specified voltage, and records control information based on the voltage detection in a storage unit of the lithium-ion secondary battery when the voltage drop differs from the voltage drop of the battery cells of a reference model by a specified amount or more.

[0015] Effects of the Invention

[0016] The control device for a lithium ion secondary battery in the present disclosure can detect abnormality of a lithium ion secondary battery more accurately than before by discovering a new sign of abnormality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an external view of an electronic device equipped with a lithium-ion secondary battery.

[0018] Figure 2 This is a functional block diagram of an electronic device equipped with a lithium-ion secondary battery.

[0019] Figure 3 It is a structural diagram of a lithium-ion secondary battery.

[0020] Figure 4 This is a graph for explaining a charging method when charging a lithium-ion secondary battery.

[0021] Figure 5 It is a graph showing the state of the charging current during CV charging.

[0022] Figure 6 This is a flow chart for detecting a current increase during CV charging.

[0023] Figure 7 This is a graph showing an example of temperature change in a battery cell block.

[0024] Figure 8 This is a flowchart showing the contents of the temperature rise detection process.

[0025] Fig. 9 This is a graph showing changes in battery voltage immediately after full charge.

[0026] Fig.10 This is a flowchart of a battery cell voltage detection process. DETAILED DESCRIPTION

[0027] Hereinafter, the embodiments will be described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming excessively lengthy and to make it easy for those skilled in the art to understand.

[0028] In addition, the inventor (etc.) provides the drawings and the following description for those skilled in the art to fully understand the present disclosure, and does not intend to limit the subject matter described in the appended claims by these.

[0029] (Implementation Method 1)

[0030] Figure 1 1 is an external view of an electronic device equipped with a lithium ion secondary battery. A personal computer 100 is equipped with a lithium ion secondary battery (not shown) for operation. The lithium ion secondary battery is housed, for example, on the bottom surface of the keyboard 101 on the back side or on the bottom rear side of the joint between the keyboard 101 and the display 102.

[0031] In this description, a personal computer is used as an example of an electronic device equipped with a lithium ion secondary battery. However, the present disclosure is not limited thereto. Any other electronic device may be used as long as it is an electronic device equipped with a lithium ion secondary battery and operates.

[0032] Figure 2 1 is a functional block diagram of an electronic device equipped with the lithium ion secondary battery described in this embodiment. A personal computer 100 includes a main body 200 and a lithium ion secondary battery 300 .

[0033] The main body 200 includes a power terminal 201 , a control unit 202 , and a load circuit 203 .

[0034] The power terminal 201 is a terminal to which a power line or the like is connected when power is supplied from the outside. The lithium ion secondary battery 300 is charged by the power supplied therefrom.

[0035] The control unit 202 controls the load circuit 203 and other hardware of the personal computer 100 . In particular, in the present embodiment, the control unit 202 controls the lithium ion secondary battery 300 .

[0036] The control unit 202 can be realized (configured) by an MPU (Micro-Processing Unit), a dedicated IC (Integrated Circuit), etc. Alternatively, the control unit 202 can be realized by a DSP (Digital Signal Processor), a FPGA (Field Programmable Gate Array), etc.

[0037] The load circuit 203 is a circuit that operates with power input from the power supply terminal 201 or power supplied from the lithium ion secondary battery 300. In the case of the personal computer 100, various devices constituting a general computer such as a CPU, a memory, and a display correspond to this.

[0038] The lithium-ion secondary battery 300 has one or more lithium-ion secondary battery cells inside. By charging and discharging these cells, power from the main body 200 can be stored or power can be supplied to the main body 200. The lithium-ion secondary battery 300 is electrically connected to the main body 200 through the + connection terminal and the - connection terminal (power connection terminal) and the data communication terminal.

[0039] Figure 3 1 is a block diagram of a lithium ion secondary battery described in this embodiment. The lithium ion secondary battery 300 includes a battery cell block 310 and a control module 320 .

[0040] The battery cell block 310 includes a rechargeable battery cell using lithium ions as an electrolyte. The battery cell block 310 includes one or more battery cells depending on the performance required of the lithium ion secondary battery.

[0041] The control module 320 controls charging and discharging of the battery cell block 310. The control module 320 includes a + terminal 321, a - terminal 322, a DATA terminal 323, a current detection resistor 324, a charging switch 325, a discharging switch 326, a fuse 327, a switch 328, a first battery control unit 329, a second battery control unit 330, a first temperature sensor 331, and a second temperature sensor 332.

[0042] The +terminal 321 and the -terminal 322 are terminals electrically connected when the lithium ion secondary battery 300 is charged from the main body 200 or when the lithium ion secondary battery 300 is discharged from the main body 200. The lithium ion secondary battery 300 and the main body 200 exchange direct current power.

[0043] The DATA terminal 323 is a terminal used when the main body 200 communicates with the lithium ion secondary battery 300. More specifically, the control unit 202 of the main body 200 and the first battery control unit 329 of the lithium ion secondary battery 300 transmit and receive data, commands, etc. via this terminal.

[0044] The current detection resistor 324 is a resistor for detecting the current of power discharged from the lithium ion secondary battery 300 or the current of power when charging the lithium ion secondary battery 300. The first battery control unit 329 measures the voltage difference between both ends thereof to calculate the current value.

[0045] The charging switch 325 and the discharging switch 326 are switches for controlling the battery cell block 310 , respectively. These switches are controlled by the first battery control unit 329 .

[0046] When charging the battery cell block 310, the first battery control unit 329 controls the charging switch 325 and the discharging switch 326 to prevent the battery cells constituting the battery cell block 310 from becoming over-voltage or over-discharged. These switches are implemented by, for example, MOSFETs.

[0047] The fuse 327 is provided for the purpose of protecting the battery cell block 310 from overcurrent or overcharge (overvoltage). When the second battery control unit 330 detects overcurrent, overvoltage, etc. to the battery cell block 310, it energizes the switch 328 to allow current to flow to the resistor of the fuse 327. The resistance of the fuse 327 causes the fuse 327 to melt due to the heat generated by the current. In this way, the battery cell block 310 is electrically disconnected to protect against overcurrent or overvoltage.

[0048] The first battery control unit 329 controls the entire lithium ion secondary battery 300 . The first battery control unit 329 communicates with the control unit 202 of the main body 200 via the DATA terminal 323 . The first battery control unit 329 calculates a current value based on a voltage difference obtained from both ends of the current detection resistor 324 .

[0049] The first battery control unit 329 also controls the charging switch 325 and the discharging switch 326. The first battery control unit 329 also obtains temperature information from the first temperature sensor 331 and the second temperature sensor 332. In addition to measuring the current and temperature, the first battery control unit 329 also measures the voltage of the battery cell block 310. In addition, when the battery cell block 310 is composed of a plurality of battery cells connected in series, not only the voltage as a whole is measured, but also the voltages of all the battery cells are measured individually.

[0050] The first battery control unit 329 is connected to a nonvolatile storage medium (not shown). These can be implemented by, for example, an EEPROM (Electrically Erasable Programmable Read-only Memory), a NAND flash memory, etc. The first battery control unit 329 records / holds the calculated current value, the obtained temperature information, and the voltage value of the battery cell block 310 in these storage media as needed. In addition, the first battery control unit 329 records the information instructed by the control unit 202 in the storage medium.

[0051] The second battery control unit 330 is provided for the purpose of protecting the battery cell block 310. When the second battery control unit 330 detects abnormality in the battery cell block 310 while the first battery control unit 329 is controlling the charging switch 325 and the discharging switch 326, the second battery control unit 330 turns on the switch 328 to blow the fuse 327.

[0052] In addition, the first battery control unit 329 and the second battery control unit 330 can be implemented (configured) by MPU (Micro-Processing Unit), dedicated IC (Integrated Circuit), etc. In addition, the first battery control unit 329 and the second battery control unit 330 can be implemented by DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), etc.

[0053] The nonvolatile storage medium connected to the first battery control unit 329 may be provided independently of the first battery control unit 329 , or may be provided inside the first battery control unit 329 .

[0054] The first temperature sensor 331 measures the temperature of the charging switch 325 and the discharging switch 326. The second temperature sensor 332 measures the temperature of the battery cell block 310. When the battery cell block 310 is composed of a plurality of battery cells, the second temperature sensor 332 may be configured to measure the temperature of each battery cell.

[0055] Figure 4 Graphs for explaining a charging method when charging a lithium ion secondary battery. The horizontal axes of the upper graph and the lower graph represent time. The vertical axis of the upper graph represents voltage, and the vertical axis of the lower graph represents current.

[0056] In the lithium-ion secondary battery described in this embodiment, charging is performed by a method called constant current constant voltage method. In this charging method, in the initial stage of charging (the period until time t1), the battery cell block 310 is charged based on a constant current. At this time, the voltage rises according to the charge amount. Hereinafter, in the description of this embodiment, this charging method is referred to as "CC charging".

[0057] When the voltage rises to near full charge, the voltage is set to be constant and charging is performed (during time t1 to t2). During charging with a constant voltage, as the voltage inside the battery cell block 310 rises, the charging current gradually decreases. Hereinafter, in the description of this embodiment, this charging method is referred to as "CV charging". When charging is completed (time t2), charging ends.

[0058] The first battery control unit 329 and the control unit 202 control the above-described charging control based on the battery voltage value acquired from the battery cell block 310 , the calculated current value, and the like.

[0059] As an important reason for lithium-ion secondary batteries to emit smoke, catch fire, etc., for example, as shown in prior art documents, overcharging of lithium-ion secondary batteries is considered. As another important reason, for example, metal foreign matter can be considered to be mixed inside the lithium-ion secondary battery. Such mixing of foreign matter is considered to be caused when foreign matter is mixed in the materials used in the manufacture of lithium-ion secondary batteries, or when foreign matter is mixed inside the battery during the manufacturing stage.

[0060] If metallic foreign matter is mixed into a lithium ion secondary battery, there is a possibility that the foreign matter may cause a small short circuit inside the battery during use of the battery.

[0061] Figure 5 It means in Figure 4 This is a graph showing the state of the charging current during CV charging described in . Figure 5 (A) and Figure 5 In (B), the horizontal axis represents time, and the vertical axis represents current value.

[0062] Figure 5 (A) is a graph showing the decrease in charging current in a normal lithium-ion secondary battery. When the lithium-ion secondary battery is normal, the charging current decreases approximately monotonically. This is because as the lithium-ion secondary battery approaches full charge, the battery resistance increases and the current value decreases.

[0063] Figure 5(B) is a graph showing the reduction of charging current when a small short circuit occurs locally inside a lithium-ion secondary battery. As the cause of an electrical short circuit inside a battery, various reasons can be considered, such as the presence of metallic foreign matter inside the battery and relatively large burrs on the electrode body. It is believed that if a short circuit occurs due to such reasons, the resistance of the lithium-ion secondary battery temporarily decreases and the current value increases.

[0064] When the short circuit phenomenon generated inside the battery converges locally, the resistance of the lithium-ion secondary battery as a whole returns to the state before the short circuit. Therefore, the reduction of the current value also returns to the original speed. It can be considered that if the short circuit phenomenon does not converge, the heat will continue, eventually leading to smoke and fire.

[0065] The inventor of the present application has continuously observed the state of lithium-ion secondary batteries that have reached the point of smoking and catching fire, and found that in lithium-ion secondary batteries that have such problems, there are cases where the above-mentioned phenomenon is observed before the problem occurs. Therefore, the inventor of the present application detects abnormal signs of lithium-ion secondary batteries by capturing this phenomenon and proposes a safer treatment.

[0066] Regarding the above detection method, use Figure 6 The processing of the flowchart is described in detail below. Figure 2 The control unit 202 and the first battery control unit 329 described in the above are performed.

[0067] (Step S601 ) The first battery control unit 329 obtains the voltage value across both ends of the current detection resistor 324 .

[0068] (Step S602 ) The first battery control unit 329 calculates a voltage difference based on the acquired voltage value across the current detection resistor 324 , and calculates a theoretical current value based on the voltage difference and the resistance value of the current detection resistor 324 .

[0069] (Step S603 ) The first battery control unit 329 transmits the calculated current value to the control unit 202 of the main body unit 200 via the DATA terminal 323 .

[0070] (Step S604) The control unit 202 records the acquired current value in a storage unit such as a memory.

[0071] (Step S605) The control unit 202 reads the current value data recorded in the storage unit in the past predetermined period (first period). The control unit 202 compares and determines whether the current value has continued to increase to a predetermined threshold value (first threshold value) or more for the predetermined period (first period) based on the read data.

[0072] If the current value continues to increase by more than the first threshold value for a predetermined period, the control unit 202 moves the process to step S606. If the current value does not increase or increases but is less than the first threshold value, the control unit 202 returns to the process of step S601.

[0073] (Step S606) The control unit 202 requests the first battery control unit 329 of the lithium ion secondary battery 300 to record control information based on the current increasing to a reference level during CV charging of the lithium ion secondary battery being used. The first battery control unit 329 receiving the request records the information in the nonvolatile storage unit.

[0074] (Step S607) The control unit 202 instructs the first battery control unit 329 to stop charging. Furthermore, the control unit 202 also instructs the first battery control unit 329 to discharge the battery. This is to discharge the power charged to the lithium-ion secondary battery 300 to stabilize the state of lithium ions. The power discharged (supplied) from the lithium-ion secondary battery 300 is input to the discharge circuit provided in the load circuit 203 of the main body 200. As a result, the power stored in the battery cell block 310 is reduced.

[0075] As described above, by detecting a sign of an increase in charging current during CV charging, it is possible to suppress the use of lithium-ion secondary batteries that are suspected of causing smoke or fire at an earlier stage than before. Therefore, lithium-ion secondary batteries can be used more safely.

[0076] Furthermore, not only the charging of the lithium ion secondary battery is stopped, but also the stored power is discharged, so that the lithium ion secondary battery can be put into a more stable state. Thus, the lithium ion battery can be used more safely than before.

[0077] In the above step S605, the control unit 202 detects the current increase by detecting that the current value continues to increase to a "first threshold value" for a "predetermined period (first period)". The "predetermined period (first period)" and the "first threshold value" may also be set as follows.

[0078] In addition, when setting the "predetermined period (first period)" and the "first threshold", the following points need to be considered. Figure 5 In the description of , the current decreases during CV charging. However, in actual products, even if the lithium-ion secondary battery 300 is normal, the current may not decrease purely due to noise or other important reasons. Therefore, when setting the "prescribed period (first period)" and "first threshold", the influence of such noise, etc. needs to be considered.

[0079] As a combination of the above-mentioned "predetermined period (first period)" and "first threshold", various combinations can be considered. For example, when the target device is a device such as a personal computer, a current increase of 500 mA (first threshold) or more is confirmed for a period of 1 second (predetermined period (first period)), a current increase of 80 mA or more is confirmed for a period of 2 seconds, a current increase of 30 mA or more is confirmed for a period of 3 seconds, a current increase of 10 mA or more is confirmed for a period of 5 seconds, etc. can be considered.

[0080] The control unit 202 may also only determine whether the conditions involved in any one of the above-mentioned multiple combinations are satisfied, thereby detecting (determining) whether there is an increase in current, and continuously determine whether the conditions are satisfied for each of the multiple combinations, and when the conditions involved in any one of the combinations are satisfied, it may also be determined (detected) that an increase in current has occurred. Alternatively, the control unit 202 may also determine (detect) that an increase in current has occurred when the conditions of two of the above-mentioned multiple combinations are satisfied. By combining multiple judgment criteria for judgment, or judging based on one judgment criterion, a higher-precision detection can be performed that suppresses the influence of interference such as noise.

[0081] Regarding the detection of the above-mentioned current increase, the accuracy can be further improved by implementing it in a state where the charging power of the lithium-ion secondary battery 300 meets the prescribed conditions during CV charging. Specifically, when the power consumption of the load circuit 203 increases, if the total of the power supplied to the load circuit 203 and the charging power to the lithium-ion secondary battery 300 exceeds the supply capacity of the external power supply supplied from the power terminal 201, the charging power is reduced. Thereafter, when the power consumption of the load circuit 203 decreases, the reduction of the charging power is released. In this way, the charging current varies according to the operating state of the load circuit. Taking this into account, the conditions for maintaining the power supplied to the lithium-ion secondary battery regardless of how the load circuit operates are calculated, and the above-mentioned detection is performed under the condition of a current value below the current value corresponding to the power. Thus, the influence of the load circuit on the detection process during charging can be suppressed.

[0082] More preferably, the temperature change may be detected by using the first temperature sensor 331, the second temperature sensor 332, etc., while the current value is detected, and the temperature change may also be taken into consideration. By detecting the current value at a constant temperature, a higher-precision detection can be performed.

[0083] In addition, the information recorded in the first battery control unit 329 described in step S606 is described as "control information based on the current of the lithium-ion secondary battery being used increasing to above the reference during CV charging", but the information is, for example, information indicating that the phenomenon has occurred. However, this is not limited to the present disclosure. For example, even if it is information other than the above, as long as it is information that prohibits the subsequent use of the lithium-ion secondary battery 300 based on this fact, and information that is required to be recorded due to this fact, the logical meaning of the recorded information is not particularly limited.

[0084] In addition, in step S607, the following processing may be further added. Specifically, when the control unit 202 determines in step S605 that the current value increases under the specified conditions, the control unit 202 notifies the CPU (not shown) constituting the load circuit 203, etc., to seek to stop using the lithium-ion secondary battery 300. The personal computer 100 performs the following processing: displaying a warning on the display 102 that strongly recommends the user to stop using the lithium-ion secondary battery 300, or automatically ending the processing after a certain period of time, or displaying on the display 102 the period during which the lithium-ion secondary battery 300 in use can be used. In this way, the user can save and back up necessary data.

[0085] In addition, when the processing from steps S601 to S603 of the lithium ion secondary battery 300 and the processing from steps S604 to S605 of the main body 200 are performed synchronously, Figure 6 . However, the present disclosure is not limited to this. For example, the two processes can also be processed independently. For example, in steps S601 to S603, it is sufficient to return to step S601 after the processing of step S603 is completed. In addition, in steps S604 to S605, if the current value does not increase by more than the specified value in the judgment of step S605, it is sufficient to return to step S604. The two independent processes can maintain the relationship by using the data transmitted from the lithium-ion secondary battery 300 to the main body 200.

[0086] (Implementation Method 2)

[0087] In this embodiment, the detection of abnormal signs of lithium ion secondary batteries by observing the temperature is described. Figures 1 to 3 The structures described are the same, so the description is omitted.

[0088] Figure 7 1 is a graph showing an example of temperature change of the battery cell block 310 when the lithium-ion secondary battery 300 is connected to the main body 200 and discharged or charged.

[0089] Figure 7 The horizontal axis of the graph represents time, and the vertical axis represents temperature. If a large temperature rise occurs as shown after time t7, a short circuit may occur inside the battery cell block 310, and the short circuit may not be suppressed, resulting in smoke or fire.

[0090] In the present application, the purpose is to detect the temperature rise shown in the period from time t5 to time t6 (second period). The inventor of the present application found that the temperature rise from time t5 to time t6 (second period) generated under certain conditions can be a sign of a large temperature rise occurring after time t7. Therefore, in the present application, a phenomenon that can be such a sign is detected.

[0091] Figure 8 1 is a flow chart showing the contents of the temperature rise detection process described in this application. Figure 8 The flowchart of FIG. 1 is used to explain the sign detection using temperature.

[0092] (Step S801 ) The first battery control unit 329 obtains temperature information of the battery cell block 310 from the second temperature sensor 332 .

[0093] (Step S802 ) The first battery control unit 329 transmits the temperature information of the battery cell block 310 to the control unit 202 via the DATA terminal 323 .

[0094] (Step S803 ) The control unit 202 records the temperature information of the battery cell block 310 acquired from the first battery control unit 329 in the storage unit.

[0095] (Step S804) The control unit 202 confirms the temperature conditions within the past prescribed time (second period) recorded in the storage unit. Specifically, the control unit 202 determines whether the temperature of the battery cell block 310 within the prescribed time (second period) has risen to or above a predetermined threshold value (second threshold value). When the temperature of the battery cell block 310 has risen to or above the predetermined threshold value (second threshold value), the control unit 202 transfers to the processing of step S805. Even if the temperature of the battery cell block 310 decreases, remains constant, or rises, if the temperature is less than the predetermined threshold value (second threshold value), the control unit 202 returns to the processing of step S801.

[0096] (Step S805) The control unit 202 requests the first battery control unit 329 to record control information based on the detection of a temperature rise exceeding a predetermined range in the lithium ion secondary battery 300 being used via the DATA terminal 323. Upon receiving the request, the first battery control unit 329 records the information in the internal storage unit.

[0097] The above-mentioned "control information based on the detection of a temperature rise above a predetermined range in the lithium-ion secondary battery 300 in use" is not limited to information indicating that the phenomenon has occurred. In addition, as long as the information indicates that the subsequent use of the lithium-ion secondary battery 300 is prohibited based on the phenomenon, and the information is required to be recorded due to the fact, the logical meaning of the recorded information is not particularly limited.

[0098] (Step S806) When the lithium-ion secondary battery 300 is being charged, the control unit 202 instructs the first battery control unit 329 to stop charging. Furthermore, the control unit 202 instructs the first battery control unit 329 to discharge the power stored in the battery cell block 310. The power discharged (supplied) from the lithium-ion secondary battery is input to the discharge circuit provided in the load circuit 203 of the main body 200. As a result, the power stored in the battery cell block 310 is reduced.

[0099] In addition, in the above description, the process of obtaining only the temperature of the battery cell block 310 and making a judgment based on the temperature is described. However, the content of the present application is not limited to this. For example, the temperature of the surrounding environment of the lithium-ion secondary battery 300 can also be obtained, and the temperature of the battery cell block 310 can be calculated by the first battery control unit 329 taking into account the temperature information. In this way, the control unit 202 can obtain the temperature of the battery cell block 310 with further improved accuracy while suppressing the influence of noise.

[0100] In addition, the "prescribed conditions" used in step S804 are not limited to the above-mentioned numerical contents. This is because these prescribed conditions vary depending on the number of cells used and the capabilities of each cell. For example, for lithium-ion secondary batteries such as notebook PCs, the condition of step S804 may be established when a temperature rise of 3 degrees or more is detected by any battery cell during a period of 10 seconds. In addition, for lithium-ion secondary batteries used as a power source for a car, the condition of step S804 may also be established when a temperature rise of 1.4 degrees or more is detected by any battery cell within 10 seconds.

[0101] In addition, when the processing of steps S801 to S806 is performed during the discharge of the lithium-ion secondary battery, that is, when the load circuit 203 of the main body 200 is operated by the power supplied by the lithium-ion secondary battery, in step S806, the control unit 202 of the main body 200 terminates the operation of the power supply from (1) the lithium-ion secondary battery after a certain period of time, (2) if there are other power sources such as external power sources, the load circuit 203 is switched to an operation based on these other power sources, and (3) after a certain period of time, the power remaining in the lithium-ion secondary battery is consumed by the dedicated circuit for discharge. Thus, the user of the main body 200 can continue to use it. In addition, the power remaining in the lithium-ion secondary battery is consumed by the dedicated circuit for discharge, which can enable the main body 200 to migrate to a stable state.

[0102] When the processing from steps S801 to S806 is not being executed while the lithium ion secondary battery is being charged or discharged, the remaining power in the lithium ion secondary battery is consumed by the dedicated discharge circuit, thereby making it possible to shift the lithium ion secondary battery to a more stable state.

[0103] exist Figure 8 The case where the processing from step S801 to S802 of the lithium-ion secondary battery 300 is synchronized with the processing of steps S803 to S806 of the main body 200 is described. However, the contents described in this application are not limited to this. For example, the two processes can also be processed independently. In this case, the processing of steps S801 to S802 returns to step S801 after the processing of step 802 is completed. In the case where the temperature does not increase by more than a specified value during the processing of step S804, the processing of steps S803 to S806 can be dealt with by returning the processing to step S803. The two independent processes can maintain the relationship using the data transmitted from the lithium-ion secondary battery 300 to the main body 200.

[0104] As described above, by detecting the temperature change of the battery cell block 310, the phenomenon of the lithium ion secondary battery 300 emitting smoke or catching fire can be detected, and the use of lithium ion secondary batteries with the possibility of abnormality can be suppressed. As a result, lithium ion secondary batteries can be used more safely.

[0105] (Implementation 3)

[0106] In this embodiment, the abnormal sign detection of the lithium ion secondary battery by observing the voltage is described. Figures 1 to 3 The structure is the same as that of Implementation 1, so the description of this part is omitted.

[0107] Fig. 93 is a graph showing changes in battery voltage under no load immediately after the battery cell block 310 is fully charged. Immediately after being fully charged, the battery cell block 310 of the lithium ion secondary battery 300 is naturally discharged, and its battery voltage decreases over time. Fig. 9 (A) Fig. 9 (B) Fig. 9 The horizontal axis of (C) represents time, and the vertical axis represents the battery voltage of the cells constituting the battery cell block 310 .

[0108] Fig. 9 (A) is a graph showing a state in which the voltage of each cell constituting the battery cell block 310 drops substantially uniformly. In this way, the voltage of each battery cell constituting a normal lithium ion secondary battery 300 drops substantially uniformly.

[0109] Fig. 9 (B) is a graph showing a situation where the voltage drop of one of the battery cells constituting the battery cell block 310 is faster than the voltage drop of the other battery cells.

[0110] Fig. 9 (C) is a graph showing a situation in which the voltage of one of the battery cells constituting the battery cell block 310 changes while always being lower than the voltages of the other battery cells.

[0111] The inventors of the present application have found that in lithium-ion secondary batteries that may emit smoke or catch fire, it is easy to detect the above-mentioned Fig. 9 (B) Fig. 9 Therefore, the inventors of the present application have studied a method for detecting a lithium-ion secondary battery that may emit smoke or catch fire in advance by observing a voltage drop in a battery cell after the lithium-ion secondary battery is fully charged.

[0112] Fig.10 This is a flowchart of the voltage detection process of the battery cell described in this application.

[0113] (Step S1001 ) The first battery control unit 329 obtains the voltage value of each battery cell constituting the battery cell block 310 .

[0114] (Step S1002 ) The first battery control unit 329 transmits the acquired voltage value of each battery cell to the control unit 202 of the main body unit 200 via the DATA terminal 323 as voltage information.

[0115] (Step S1003 ) The control unit 202 stores the voltage information acquired from the first battery control unit 329 in the storage unit.

[0116] (Step S1004) The control unit 202 reads the voltage information of each cell stored in the storage unit in step S1003 up to the specified period (third period) and calculates the voltage drop rate of each battery cell. The control unit 202 compares the calculated voltage drop rates of each battery cell.

[0117] Specifically, if Fig. 9 As described in (B) of FIG. 3 , the control unit 202 determines whether the following conditions are met: the voltage of any of the battery cells constituting the battery cell block 310 decreases faster than the other battery cells at a predetermined rate, or the voltage of the battery cell decreases by a predetermined amount or more. The control unit 202 can make a numerical judgment based on how much the voltage value of the battery cell in the predetermined period (third period) differs from the voltage value of the other battery cells or the battery cell of the reference model that serves as the reference for judgment.

[0118] If any of the battery cells constituting the battery cell block 310 meets the above conditions, the control unit 202 transfers the process to step S1005. If not, the control unit 202 returns the process to step S1001.

[0119] (Step S1005)

[0120] When the control unit 202 determines that the speed of voltage drop of the battery cells constituting the battery cell block 310 is greater than a predetermined value or the amount of voltage drop of the battery cells within a predetermined period is greater than a predetermined value, the control unit 202 records the information in the storage unit.

[0121] (Step S1006) The control unit 202 determines whether the voltage of the battery cells constituting the battery cell block 310 is Fig. 9 As shown in (C), whether a stable difference of more than a specified amount has occurred between the battery cells, or whether the above voltage has dropped by more than a specified amount. In this judgment, the battery cell in which the abnormal voltage drop rate is detected in step S1004 is the object, and the detection is performed in a charging cycle different from the charging cycle detected in step S1004.

[0122] That is, the control unit 202 confirms that Fig. 9 Does a battery cell with a fast voltage drop as shown in (B) of FIG. 10 occur in a charging cycle after the charging cycle in which the voltage drop is detected? Fig. 9 Thus, the accuracy of detecting a lithium ion secondary battery that may become abnormal can be further improved.

[0123] If it is confirmed in step S1005 that the voltage of the battery cell to be recorded is steadily decreasing in this step, the control unit 202 transfers the process to step S1007. On the other hand, if a stable voltage decrease is not observed, the control unit 202 returns the process to step S1001.

[0124] (Step S1007) The control unit 202 requests the first battery control unit 329 to record control information based on the abnormal voltage drop in the battery cell block 310 of the lithium ion secondary battery 300 in use via the DATA terminal 323. Upon receiving the request, the first battery control unit 329 records the information in the internal storage unit.

[0125] Here, "control information based on abnormal voltage drop in battery cell block 310 of lithium-ion secondary battery 300" may be information indicating that the phenomenon has occurred, information indicating that the subsequent use of lithium-ion secondary battery 300 is prohibited due to the occurrence of the phenomenon, and information requiring recording due to the phenomenon. "Control information based on abnormal voltage drop in battery cell block 310 of lithium-ion secondary battery 300" does not particularly limit the logical meaning of the recording.

[0126] (Step S1008) The control unit 202 instructs the first battery control unit 329 to discharge the power stored in the battery cell block 310. The power discharged (supplied) from the lithium ion secondary battery 300 is input to the discharge circuit provided in the load circuit 203 of the main body 200. As a result, the power stored in the battery cell block 310 is reduced.

[0127] As described above, by detecting the voltage change of the battery cells constituting the battery cell block, the phenomenon of smoke or fire of the lithium ion secondary battery 300 can be detected at an earlier stage than before, and the use of lithium ion secondary batteries with the possibility of abnormality can be suppressed. As a result, lithium ion secondary batteries can be used more safely.

[0128] In the above step S1004, in determining whether the voltage drop is abnormal, Fig. 9 (B) Fig. 9 The case shown in (C) is used as an example, but the contents described in the present application are not limited thereto. In addition, in the comparison between the cells constituting the battery cell block 310, when it can be detected that only one cell is in a different electrical state, it can also be based on these.

[0129] In addition, Fig.10The voltage detection process described in the above can further improve the detection accuracy by judging the state after a certain time, such as 3 minutes, 5 minutes, 10 minutes, etc., has passed since the lithium-ion secondary battery 300 was fully charged (fully charged state). This is because it can be considered that the voltage drops greatly as a normal operation just after charging is stopped, so it is difficult to improve the detection accuracy even if detection is performed at this time.

[0130] also, Fig.10 The detection process needs to be implemented after full charging, in a state where power is not transferred between the main body 200 and the lithium-ion secondary battery, that is, in a no-load state where neither charging nor discharging is performed on the lithium-ion secondary battery. If power is supplied (discharged) to the main body 200, especially the load circuit 203, the lithium-ion secondary battery 300 is affected by the load circuit 203 and the battery voltage moves up and down, so that the detection in the detection process described above becomes difficult. The battery voltage of each cell of the battery cell block 310 is affected by the main body 200 such as the load circuit 203, and the accuracy of the detection process is reduced. In addition, even when the lithium-ion secondary battery is charged, the charging power varies due to the influence of the size of the load on the main body side, and the accuracy of the detection process is also reduced. Therefore, in order to maintain and improve the accuracy, it is required to seek a state equivalent to no electrical connection during the detection period in which neither charging nor discharging of the lithium-ion secondary battery 300 is performed.

[0131] In addition, in the above description, it is described as "after full charge (after the charge becomes fully charged)", but it does not need to be fully charged. For example, it can also be performed when the battery cell block 310 has a battery voltage above the specified value, such as 80% or more relative to the specified battery voltage. Fig.10 In addition, each time the voltage of the lithium-ion secondary battery reaches 20%, 40%, 60%, 80%, etc. of the specified battery voltage, charging may be stopped, and the control unit 202 and the first battery control unit 329 may implement Fig.10 Processing shown.

[0132] In addition, Fig. 9 , Fig.10 In the example, the battery cell block 310 is described on the premise that it includes a plurality of cells, but the contents described in the present application are not limited to this. In the case where the battery cell block 310 includes only one battery cell, the control unit 202 may also have a reference model or the like in advance as a comparison object, and compare the reference model with the measured voltage value. Thus, the same detection can be performed even in the case of a single cell.

[0133] Furthermore, when the battery cell block 310 is composed of only one battery cell, the Fig.10 This is because in the case of a single battery cell, detection can be performed with high accuracy.

[0134] In addition, Fig.10 In the figure, it is described that the processing from step S1001 to S1002 of the lithium-ion secondary battery 300 and the processing of steps S1003 to S1009 of the main body 200 are performed synchronously. However, this is not limited to the present disclosure. For example, the two processes can also be performed independently. For example, in steps S1001 to S1002, it is sufficient to return to step S1001 after completing the processing of step S1002. In addition, in steps S1003 to S1009, it is sufficient to return to step S1003 after completing the processing of steps S1005, S1006, and S1007. The two independent processes can maintain the relationship by using the data transmitted from the lithium-ion secondary battery 300 to the main body 200.

[0135] In addition, in step S1009, the following processing may be further added. Specifically, the control unit 202 notifies the CPU (not shown) constituting the load circuit 203, etc., to seek to stop using the lithium-ion secondary battery 300. The personal computer 100 performs the following processing: displaying a warning on the display 102 that strongly recommends the user to stop using the lithium-ion secondary battery 300, or automatically ending the processing after a certain period of time, or displaying on the display 102 the period when the lithium-ion secondary battery 300 in use can be used. In this way, the user can save and back up necessary data.

[0136] As described above, Embodiments 1 to 3 have been described as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto. In particular, descriptions using numerical values ​​are not limited to the contents described.

[0137] Furthermore, the technical contents described in the first to third embodiments can also be applied to embodiments in which appropriate changes, substitutions, additions, omissions, etc. are made. Furthermore, the constituent elements described in the first to third embodiments can be combined to form new embodiments.

[0138] For example, the entire conditions of the charging current, temperature, and voltage described in Embodiments 1 to 3 may be confirmed to detect a sign. In this case, when any one, two of the three, or all of the three sign conditions are met, charging may be stopped and the power stored in the battery cell block 310 may be discharged. Which of the three sign conditions is used may be set for each electronic device according to the safety level required by the electronic device using the lithium-ion secondary battery 300.

[0139] In embodiments 1 to 3, the case where the main body 200 and the lithium-ion secondary battery 300 are independent is used as an example for description. However, the present disclosure is not limited to this. For example, the main body 200 and the lithium-ion secondary battery 300 may be fixedly assembled in one device. In addition, when the present disclosure is applied to a device for controlling the charging and discharging of a lithium-ion secondary battery, it may be configured as a device independent of other devices, or it may be configured as a single device.

[0140] In embodiments 1 to 3, use Figure 6 , 8 , and flowcharts of 10 and the like have been described for explaining the control device and control method according to the present disclosure. However, the control device and control method in Embodiments 1 to 3 are examples of implementations of the control device and control method according to the present disclosure, and are not limited thereto.

[0141] In the description of embodiments 1 to 3, it is described that when a sign is detected, charging is stopped and the stored power is discharged. However, in the present disclosure, it is not limited to this. For example, in the personal computer 100, a warning screen may be displayed to the user for a certain period of time, and then the computer may be forced to switch to a sleep mode or perform a shutdown operation. The action when a sign is detected may be appropriately performed according to the purpose of the electronic device connected to the lithium-ion secondary battery, the reliability required for the electronic device, etc.

[0142] Industrial Applicability

[0143] The technology described in the present application can be industrially utilized in electronic devices using lithium-ion secondary batteries and the like.

[0144] Explanation of symbols

[0145] 100 PCs

[0146] 101 Keyboard

[0147] 102 Display

[0148] 200 Main body

[0149] 201 Power terminal

[0150] 202 Control Department

[0151] 203 Load Circuit

[0152] 300 Lithium-ion secondary battery

[0153] 310 battery cell block

[0154] 320 Control Module

[0155] 321 + terminal

[0156] 322 - Terminal

[0157] 323 DATA terminal

[0158] 324 Current Sense Resistor

[0159] 325 Charging switch

[0160] 326 Discharge switch

[0161] 327 Fuse

[0162] 328 Switch

[0163] 329 1st Battery Control Unit

[0164] 330 Second battery control unit

[0165] 331 1st temperature sensor

[0166] 332 2nd temperature sensor.

Claims

1. A control device for a lithium-ion secondary battery, which is a control device for controlling a lithium-ion secondary battery, characterized in that: Equipped with a control unit, The control unit detecting a charging current when the lithium-ion secondary battery is charged at a constant voltage, When the charging current increases by more than the prescribed amount within the prescribed time for any one of a plurality of combinations of the prescribed amount within the prescribed time, stopping charging of the lithium ion secondary battery and recording control information based on the increase in charging current in a storage unit provided in the lithium ion secondary battery, Regarding the plurality of combinations of the prescribed time and the prescribed amount, the longer the prescribed time is, the smaller the size of the prescribed amount is.

2. The control device for a lithium-ion secondary battery according to claim 1, wherein: The control unit further discharges the electric power stored in the lithium ion secondary battery when the charging current increases by a predetermined amount or more within a predetermined time.

3. A control method for a lithium-ion secondary battery, characterized in that have: a step of detecting a charging current when constant voltage charging is performed on the lithium ion secondary battery; and When the charging current increases by more than the prescribed amount within the prescribed time for any one of a plurality of combinations of the prescribed amount within the prescribed time, a control step of stopping charging of the lithium ion secondary battery and recording control information based on the increase in the charging current in a storage unit provided in the lithium ion secondary battery, Regarding the plurality of combinations of the prescribed time and the prescribed amount, the longer the prescribed time is, the smaller the size of the prescribed amount is.

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