Battery capacity calculation device and battery capacity calculation method

Abstract

The invention provides a battery capacity calculation device and a battery capacity calculation method, which can calculate full charge capacity with high frequency. The battery capacity calculation device includes a controller. The controller acquires a first voltage value and a charging current value of a battery during charging of the battery, acquires a second voltage value of the battery during pause of charging of the battery, and calculates an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value. The number of cycles of the battery is acquired, the time during which the temperature of the battery is included in a predetermined temperature range and the output voltage value of the battery is included in a predetermined voltage range is acquired, and the full charge capacity of the battery is calculated by using the number of cycles, the impedance value, and the time.

Description

Technical Field

[0001] The invention relates to a battery capacity calculation device and a battery capacity calculation method. Background Art

[0002] The development of products that users use for a long time is related to the reduction of carbon emissions. Users can reduce electronic waste (E-waste) and improve environmental issues by replacing the batteries of electronic devices such as laptop PCs (Personal Computers) at appropriate times. Therefore, it is desirable to have a function that prompts users to replace batteries at appropriate times.

[0003] As a function for notifying the user of the degree of battery degradation, there is a function for inferring the state of the battery based on the capacity retention rate and the number of cycles, and displaying the state. The capacity retention rate is obtained by dividing the full charge capacity (FCC: Full Charge Capacity) by the design capacity. In addition, there is a known prior art that calculates the full charge capacity based on the current value until the battery changes from a fully charged state to a fully discharged state.

[0004] The device disclosed in Patent Document 1 selects a method for estimating the full charge capacity according to the state of the battery, and estimates the full charge capacity using the selected method.

[0005] Patent document 1: Japanese Patent Application Publication No. 2021-125320.

[0006] In the conventional technique of estimating the full charge capacity, the battery needs to be fully discharged, and therefore the full charge capacity is calculated less frequently. Summary of the invention

[0007] An object of the present invention is to provide a battery capacity calculation device and a battery capacity calculation method capable of calculating a full charge capacity at a high frequency.

[0008] One embodiment of the present invention provides a battery capacity calculation device, which includes a controller, wherein the controller obtains a first voltage value and a charging current value of the battery during charging of the battery, obtains a second voltage value of the battery during a pause in charging of the battery, calculates an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value, calculates a ratio of the impedance value to an initial impedance value pre-recorded in a memory, that is, an impedance increase, obtains the number of cycles of the battery, obtains a time when the temperature of the battery is within a specified temperature range and the output voltage value of the battery is within a specified voltage range, and calculates the full charge capacity of the battery by using the number of cycles, the impedance increase, and the time.

[0009] In one embodiment of the present invention, the controller can calculate the full charge capacity according to the mathematical formula FCC=1.0+a*CYC+b*HTVT+c*IMP, wherein FCC is the full charge capacity, CYC is the number of cycles, HTVT is the time, IMP is the impedance increase, and a, b, and c are specified coefficients.

[0010] In one aspect of the present invention, the controller may correct the impedance value according to the temperature during charging of the battery.

[0011] In one embodiment of the present invention, the controller may record the calculated full charge capacity and the time information of the time when the full charge capacity is calculated in a memory, and calculate the time until the full charge capacity of the battery becomes less than a specified capacity by using the full charge capacity and the time information recorded in the memory.

[0012] One embodiment of the present invention provides a battery capacity calculation device, which includes a controller, wherein the controller obtains a first voltage value and a charging current value of the battery during charging of the battery, obtains a second voltage value of the battery during a period of suspending charging of the battery, calculates an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value, calculates a ratio of the impedance value to an initial impedance value pre-recorded in a memory, that is, an impedance increase, obtains the number of cycles of the battery, and calculates the full charge capacity of the battery by using the number of cycles and the impedance increase.

[0013] One embodiment of the present invention provides a battery capacity calculation method, comprising the following steps: obtaining a first voltage value and a charging current value of the battery during charging of the battery; obtaining a second voltage value of the battery during a period of suspending charging of the battery; calculating an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value; calculating a ratio of the impedance value to an initial impedance value pre-recorded in a memory, that is, an impedance increase; obtaining the number of cycles of the battery; obtaining the time when the temperature of the battery is within a specified temperature range and the output voltage value of the battery is within a specified voltage range; and calculating the full charge capacity of the battery by using the number of cycles, the impedance increase, and the time.

[0014] One embodiment of the present invention provides a battery capacity calculation method, comprising the following steps: obtaining a first voltage value and a charging current value of the battery during charging of the battery; obtaining a second voltage value of the battery during a period of suspending charging of the battery; calculating an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value; calculating an impedance increase, which is a ratio of the impedance value to an initial impedance value pre-recorded in a memory; obtaining the number of cycles of the battery; and calculating the full charge capacity of the battery by using the number of cycles and the impedance increase.

[0015] According to the present invention, a battery capacity calculation device and a battery capacity calculation method can calculate a full charge capacity at a high frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a block diagram showing a hardware configuration example of an electronic device according to the first embodiment of the present invention.

[0017] Figure 2 This is a block diagram showing an example of the structure of a battery according to the first embodiment of the present invention.

[0018] Figure 3 This is a flowchart showing an example of the impedance value calculation process according to the first embodiment of the present invention.

[0019] Figure 4 This is a diagram showing an example of changes in the voltage of the battery according to the first embodiment of the present invention.

[0020] Figure 5 This is a diagram showing an example of changes in the voltage of the battery according to the first embodiment of the present invention.

[0021] Figure 6 This is a diagram showing an example of impedance of the battery according to the first embodiment of the present invention.

[0022] Figure 7 This is a diagram showing an example of correction coefficients according to the first embodiment of the present invention.

[0023] Figure 8 This is a flowchart showing an example of capacity calculation processing according to the first embodiment of the present invention.

[0024] Fig. 9 An example of the relationship between the number of cycles and the capacity retention rate and the relationship between the number of cycles and the impedance increase according to the first embodiment of the present invention is shown.

[0025] Fig.10 This is a diagram showing an example of the relationship between the impedance increase and the capacity maintenance rate of the battery according to the first embodiment of the present invention.

[0026] Fig.11This is a diagram showing an example of the relationship between the impedance increase and the capacity maintenance rate of the battery according to the first embodiment of the present invention.

[0027] Fig.12 This is a block diagram showing an example of the structure of a battery according to the second embodiment of the present invention.

[0028] Fig.13 This is a flowchart showing an example of capacity calculation processing according to the second embodiment of the present invention.

[0029] Fig.14 This is a diagram showing an example of a time change of the full charge capacity according to the second embodiment of the present invention.

[0030] Description of Reference Numerals

[0031] 10…electronic device; 11…CPU; 12…main memory; 13…video subsystem; 14…display unit; 21…chip set; 22…BIOS memory; 23…storage medium; 24…audio system; 25…WLAN card; 26…USB connector; 31…embedded controller; 32…input unit; 33…power supply circuit; 40, 40a…battery; 41…battery; 42…BMU; 43, 43a…battery capacity calculation device; 44, 44a…controller; 45…memory; 440…state acquisition unit; 441…impedance value calculation unit; 442…battery capacity calculation unit; 443…memory control unit; 444…charging control unit; 445…life estimation unit. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0033] (First Embodiment)

[0034] A first embodiment of the present invention will be described. Figure 1 It is a block diagram showing an example of the hardware configuration of the electronic device 10 according to the present embodiment.

[0035] The electronic device 10 includes a CPU 11 , a main memory 12 , a video subsystem 13 , a display unit 14 , a chipset 21 , a BIOS memory 22 , a storage medium 23 , an audio system 24 , a WLAN card 25 , a USB connector 26 , an embedded controller 31 , an input unit 32 , a power circuit 33 , and a battery 40 .

[0036] The CPU 11 executes various calculation processes under program control to control the entire electronic device 10. For example, the CPU 11 executes processes based on programs of an OS (Operating System) and a BIOS (Basic Input Output System). The CPU 11 is an example of a processor.

[0037] The main memory 12 is a writable memory used as a read area for the execution program of the CPU 11 or as a work area for writing processing data of the execution program. The main memory 12 is composed of, for example, a plurality of DRAM (Dynamic Random Access Memory) chips. The execution program includes various drivers, various services / utilities, and application programs for operating the OS and peripheral devices.

[0038] The video subsystem 13 is a subsystem for realizing functions related to image display, and includes a video controller. The video controller processes the rendering command from the CPU 11, writes the processed rendering information into the video memory, and reads the rendering information from the video memory and outputs it to the display unit 14 as rendering data (display data).

[0039] The display unit 14 is, for example, a liquid crystal display or an organic EL display, and displays a display screen based on the drawing data (display data) output from the video subsystem 13 .

[0040] The chipset 21 includes controllers such as USB (Universal Serial Bus), Serial ATA (AT Attachment), SPI (Serial Peripheral Interface) bus, PCI (Peripheral Component Interconnect) bus, PCI-Express bus, and LPC (Low Pin Count) bus, and is connected to a plurality of devices. For example, the plurality of devices include a BIOS memory 22, a storage medium 23, an audio system 24, a WLAN card 25, a USB connector 26, and an embedded controller 31, which are described later.

[0041] The BIOS memory 22 is composed of an electrically rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash ROM. The BIOS memory 22 stores BIOS programs and system firmware for controlling the embedded controller 31. The BIOS memory 22 is an example of a sub-memory.

[0042] The storage medium 23 includes a HDD (Hard Disk Drive) or an SSD (Solid State Drive), etc. For example, the storage medium 23 stores an OS, various drivers, various services / utilities, application programs, and various data.

[0043] The audio system 24 is connected to a microphone and a speaker (not shown) to record, reproduce, and output audio data. In addition, as an example, the microphone and the speaker are built in the electronic device 10.

[0044] The WLAN (Wireless Local Area Network) card 25 is connected to a network via a wireless LAN to perform data communication. When receiving data from the network, the WLAN card 25 generates an event trigger indicating the reception of data. The USB connector 26 is a connector for connecting peripheral devices using USB.

[0045] The input unit 32 also represents an input device (input device) included in the electronic device 10 . The input device included in the input unit 32 outputs input information input by a user's operation to the embedded controller 31 .

[0046] The power circuit 33 includes, for example, a DC / DC converter, a charging and discharging unit, and an AC / DC adapter. For example, the power circuit 33 converts a DC voltage supplied from an external power source such as an AC adapter (not shown) or a battery 40 into a plurality of voltages required for the electronic device 10 to operate. In addition, the power circuit 33 supplies power to each part of the electronic device 10 based on the control from the embedded controller 31.

[0047] The battery 40 is, for example, a secondary battery such as a lithium ion battery. When power is supplied from an external power source to the electronic device 10, the battery 40 is charged via the power circuit 33. When power is not supplied from an external power source to the electronic device 10, the battery 40 outputs the stored power as operating power for the electronic device 10 via the power circuit 33.

[0048] The embedded controller 31 is a one-chip microcomputer that monitors and controls various devices (peripheral devices and sensors, etc.) regardless of the state of the system of the electronic device 10. The embedded controller 31 includes a CPU, ROM, RAM, A / D input terminals of multiple channels, D / A output terminals, a timer, and digital input and output terminals (not shown). The input unit 32 and the power supply circuit 33 are connected to the digital input and output terminals of the embedded controller 31, and the embedded controller 31 controls their operations. In addition, the embedded controller 31 controls the change of the clock frequency of the CPU 11 via the chipset 21.

[0049] Figure 2 An example of the structure of the battery 40 of this embodiment is shown. The battery 40 includes a battery 41, a BMU (Battery Management Unit) 42, and a battery capacity calculation device 43. The battery capacity calculation device 43 may be included in the BMU 42.

[0050] For example, the battery 41 is a lithium ion battery. The BMU 42 monitors various states of the battery 41 and acquires information related to the various states from the battery 41. For example, the BMU 42 acquires the voltage value, current value, temperature, etc. of the battery 41 from the battery 41.

[0051] The battery capacity calculation device 43 includes a controller 44 and a memory 45. The controller 44 includes an MPU (MicroProcessing Unit) and the like. The memory 45 includes a storage medium such as a RAM.

[0052] As a functional configuration of processing executed by the MPU, the controller 44 includes a state acquisition unit 440, an impedance value calculation unit 441, a battery capacity calculation unit 442, a memory control unit 443, and a charge control unit 444. The functions of the controller 44 may be implemented in battery firmware.

[0053] The state acquisition unit 440 acquires information related to various states of the battery 41 from the BMU 42. The impedance value calculation unit 441 calculates the impedance value of the battery 41 by using the information acquired from the BMU 42. The battery capacity calculation unit 442 calculates the full charge capacity of the battery 41 by using the information acquired from the BMU 42 and the impedance value calculated by the impedance value calculation unit 441. The memory control unit 443 controls the reading and writing of data between the controller 44 and the memory 45. The charging control unit 444 controls the charging of the battery 41 via the BMU 42.

[0054] Reference Figure 3 , the impedance value calculation process executed by the controller 44 is described. Figure 3FIG. 4 is an example of the impedance value calculation process of the present embodiment. The controller 44 executes Figure 3 The impedance value calculation process is shown.

[0055] (Step S100)

[0056] Each time a predetermined period of time has passed, the state acquisition unit 440 acquires information related to the SoC (State of Charge) of the battery 41 from the BMU 42. SoC indicates the charging state of the battery 41. When the battery 41 is fully charged, the SoC is 100%, and when the battery 41 is fully discharged, the SoC is 0%. The state acquisition unit 440 determines whether the charging state indicated by the SoC is a predetermined state. The predetermined state corresponds to a state in which the electronic device 10 is operating by receiving power from the battery 41 and the impedance of the battery 41 is stable. For example, the predetermined state corresponds to a SoC of 60%, 65%, 70%, 75% or 80%.

[0057] When the charging state of the battery 41 is not in the predetermined state, the controller 44 executes step S100 again. When the charging state of the battery 41 is in the predetermined state, the controller 44 executes the following step S101.

[0058] When the SoC is 60%, 65%, 70%, 75%, or 80%, the controller 44 calculates the impedance value of the battery 41 as follows. Therefore, the controller 44 can calculate the impedance value of the battery 41 at a high frequency.

[0059] (Step S101)

[0060] The state acquisition unit 440 acquires information on the voltage value V1 , the current value I1 , and the temperature T of the battery 41 from the BMU 42 .

[0061] (Step S102)

[0062] After executing step S101, the charging control unit 444 stops charging of the battery 41 for 1 minute. The time for which the charging control unit 444 stops charging is not limited to 1 minute.

[0063] (Step S103)

[0064] After executing step S102 , the state acquisition unit 440 acquires information on the voltage value V2 of the battery 41 from the BMU 42 .

[0065] (Step S104)

[0066] After executing step S103, the impedance value calculation unit 441 calculates the impedance value of the battery 41 by using the voltage value V1, the voltage value V2, and the current value I1. In addition, the impedance value calculation unit 441 corrects the impedance value by using the temperature T to obtain a corrected impedance value.

[0067] Reference Figure 4 as well as Figure 5 , a method for calculating the impedance value of the battery 41 by the impedance value calculation unit 441 is described. Figure 4 An example of a change in the voltage of the battery 41 during charging is shown. Figure 5 Yes Figure 4 A magnified portion of the image.

[0068] Figure 4 The horizontal axis of the graph in represents SoC, and the vertical axis of the graph represents voltage. Figure 4 The line L1 in FIG. 1 represents the closed circuit voltage (CCV: Closed Circuit Voltage) of the battery 41 during charging. Figure 4 Points P1 to P5 on line L2 in represent the open circuit voltage (OCV: Open Circuit Voltage) of battery 41 1 minute after charging of battery 41 is stopped. When SoC is 60%, the open circuit voltage of battery 41 is at point P1. When SoC is 65%, the open circuit voltage of battery 41 is at point P2. When SoC is 70%, the open circuit voltage of battery 41 is at point P3. When SoC is 75%, the open circuit voltage of battery 41 is at point P4. When SoC is 80%, the open circuit voltage of battery 41 is at point P5.

[0069] Figure 5 express Figure 4 The voltage of the battery 41 around the point P1 in FIG. Figure 5 Point P0 on line L1 shown in FIG. 1 represents the voltage of battery 41 in step S100. State acquisition unit 440 acquires voltage value V1 and current value I1 at point P0. Figure 5 Point P1 on line L2 shown in FIG. 1 represents the voltage of battery 41 in step S103. State acquisition unit 440 acquires voltage value V2 at point P1.

[0070] The impedance value calculation unit 441 calculates the impedance value of the battery 41 by dividing the difference (V1-V2) between the voltage value V1 and the voltage value V2 by the current value I1. The impedance value calculation unit 441 also calculates the corrected impedance value by multiplying the correction coefficient corresponding to the temperature T by the impedance value.

[0071] Figure 6 An example of the impedance of a battery having the same structure as the battery 41 is shown. Figure 6The horizontal axis of the graph in represents the voltage of the battery when the SoC is 60%, and the vertical axis of the graph represents the impedance of the battery. Figure 6 The line L3 in FIG. 1 represents the impedance at a temperature of 45° C. Figure 6 The line L4 in FIG. 1 represents the impedance at a temperature of 35° C. Figure 6 The line L5 in FIG. 1 represents the impedance at a temperature of 25° C. Figure 6 The line L6 in FIG. 1 represents the impedance at a temperature of 15°C.

[0072] For example, by using a battery having the same configuration as the battery 40, the same processing as steps S101 to S103 is performed to calculate the impedance value. The impedance values ​​at various temperatures are calculated to obtain Figure 6 The data of the graph shown in the figure are used to calculate the correction coefficient corresponding to the temperature.

[0073] Figure 7 An example of the correction coefficient is shown. In this example, the reference temperature is 25°C, and the correction coefficient at the reference temperature is set to 1.00. The correction coefficient at each temperature other than the reference temperature is the ratio of the impedance value at each temperature to the impedance value at the reference temperature. Figure 7 The correction coefficients shown are recorded in advance in the memory 45 .

[0074] As the temperature increases, the correction coefficient increases. For example, when the temperature is the reference temperature (25° C.), the impedance value calculation unit 441 multiplies the impedance value by a predetermined correction coefficient (1.00). When the temperature is lower than the reference temperature, the impedance value calculation unit 441 multiplies the impedance value by a correction coefficient smaller than the predetermined correction coefficient. When the temperature is higher than the reference temperature, the impedance value calculation unit 441 multiplies the impedance value by a correction coefficient larger than the predetermined correction coefficient.

[0075] (Step S105)

[0076] After executing step S104, the memory control unit 443 records the corrected impedance value in the memory 45. The memory control unit 443 may also update the corrected impedance value recorded last in the memory 45 using the newly calculated corrected impedance value. The memory control unit 443 may also record the newly calculated corrected impedance value in the memory 45 in a state that can be identified with the corrected impedance value calculated in the past. Thereafter, the controller 44 executes step S100 again.

[0077] Reference Figure 8 , the capacity calculation process performed by the controller 44 is described. Figure 8 FIG. 4 is an example of the capacity calculation process of the present embodiment. The controller 44 executes the Figure 8The controller 44 may execute the capacity calculation process while the battery 41 is being charged, or may execute the capacity calculation process when the battery 41 is not being charged.

[0078] (Step S200)

[0079] Each time a predetermined time has passed, the memory control unit 443 determines whether a new correction impedance value is recorded in the memory 45. If the new correction impedance value is not recorded in the memory 45, the controller 44 executes step S200 again. If the new correction impedance value is recorded in the memory 45, the controller 44 executes the following step S201.

[0080] (Step S201)

[0081] The battery capacity calculation unit 442 calculates the corrected impedance increase. The corrected impedance increase is the ratio of the corrected impedance value recorded in the memory 45 to the initial impedance value. The initial impedance value is the impedance value of the battery 41 before starting to use the battery 41 (starting the initial charging of the battery 41). The impedance value of the battery 41 gradually increases from the initial impedance value as time passes. The initial impedance value is recorded in the memory 45 in advance.

[0082] (Step S202)

[0083] The state acquisition unit 440 acquires information on the number of cycles and the high temperature and high pressure time from the BMU 42 .

[0084] One cycle corresponds to a period from when the battery 41 changes from a fully discharged state to a fully charged state, and then to when it changes to a fully discharged state again. The battery 41 stores the number of cycles from when the use of the battery 41 starts.

[0085] The high temperature and high pressure time is the time (hour) during which the temperature of the battery 41 is within a predetermined temperature range and the output voltage value of the battery 41 is within a predetermined voltage range. For example, the predetermined temperature range is 45° C. or higher and 70° C. or lower. For example, the predetermined voltage range is 4.4V or higher and 4.5V or lower.

[0086] (Step S203)

[0087] After executing step S202, the battery capacity calculation unit 442 calculates the full charge capacity of the battery 41 by using the number of cycles, high temperature and high pressure time, and the corrected impedance increase. The memory control unit 443 records the full charge capacity in the memory 45. After that, the controller 44 executes step S200 again.

[0088] An example of a method of calculating the full charge capacity of the battery 41 will be described. Fig. 9An example showing the relationship between the number of cycles and the capacity retention rate, and the relationship between the number of cycles and the impedance growth. As mentioned above, the capacity retention rate is obtained by dividing the full charge capacity by the design capacity. The impedance growth is the ratio of the current impedance value to the initial impedance value.

[0089] Fig. 9 The horizontal axis of the graph in represents the cycle number, and the vertical axis of the graph represents the capacity maintenance rate and the impedance increase. Fig. 9 The line L10 shown shows the relationship between the number of cycles and the capacity retention rate. Fig. 9 The line L11 shown shows the relationship between the number of cycles and the increase in impedance. Fig. 9 As shown in FIG. 1 , if the number of cycles increases, the capacity retention rate decreases and the impedance increases. That is, if the impedance increases, the full charge capacity decreases. The battery capacity calculation unit 442 calculates the full charge capacity based on the relationship between the full charge capacity and the impedance.

[0090] Fig.10 An example of the relationship between the impedance increase and the capacity retention rate of a battery having the same configuration as the battery 41 is shown. Fig.10 The horizontal axis of the graph in represents the impedance increase, and the vertical axis of the graph represents the capacity maintenance rate.

[0091] Fig.10 The graph in the figure shows the impedance and full charge capacity measurement results obtained by degrading the battery in three different test environments, with the test environment temperatures being 25°C, 45°C, and 60°C. Fig.10 As shown, the relationship between the estimated impedance and the full charge capacity can be approximated by a straight line.

[0092] Fig.11 Express Fig.10 The three straight lines that approximate the measurement results shown are: Straight line L7 approximates the measurement results in degradation pattern 1 (test environment temperature 25°C). Straight line L8 approximates the measurement results in degradation pattern 2 (test environment temperature 45°C). Straight line L9 approximates the measurement results in degradation pattern 3 (test environment temperature 60°C).

[0093] like Fig.11 As shown in , the relationship between impedance and full charge capacity can be approximated by a straight line, and this relationship depends on temperature. Fig. 9 As shown, the relationship between the cycle number and the capacity retention rate can be approximated by a straight line. Taking these into consideration, the full charge capacity FCC of the battery 41 is expressed by the following mathematical formula (1) using the cycle number CYC, the high temperature and high pressure time HTVT, and the corrected impedance increase IMP.

[0094] FCC=1.0+a*CYC+b*HTVT+c*IMP···(1)

[0095] In the mathematical formula (1), a, b, and c are predetermined coefficients. By using a battery having the same structure as the battery 41, the impedance value and the full charge capacity at various temperatures are measured, and the number of cycles and the high temperature and high pressure time are obtained. For the result, the coefficient a, the coefficient b, and the coefficient c are calculated by applying, for example, the least square method. These coefficients are pre-stored in the memory 45. The controller 44 calculates the full charge capacity by using the mathematical formula (1).

[0096] As described above, the controller 44 obtains the first voltage value (V1) and the charging current value (I1) of the battery 41 during the charging of the battery 41. The controller 44 obtains the second voltage value (V2) of the battery 41 during the suspension of the charging of the battery 41. The controller 44 calculates the impedance value of the battery 41 by using the first voltage value, the second voltage value, and the charging current value. The controller 44 calculates the ratio of the impedance value to the initial impedance value pre-recorded in the memory 45, that is, the impedance increase. The controller 44 obtains the number of cycles of the battery 41. The controller 44 obtains the time (high temperature and high pressure time) when the temperature of the battery 41 is within the prescribed temperature range and the output voltage value of the battery 41 is within the prescribed voltage range. The controller 44 calculates the full charge capacity of the battery 41 by using the number of cycles, the impedance increase, and the high temperature and high pressure time.

[0097] In the present embodiment, the charge amount and discharge amount of the battery 41 required to calculate the full charge capacity are relatively small. Therefore, the controller 44 can calculate the full charge capacity at a high frequency.

[0098] The controller 44 calculates the full charge capacity according to the above-mentioned mathematical formula (1). The controller 44 can calculate the full charge capacity by using a simple mathematical formula.

[0099] The controller 44 may calculate the full charge capacity without using the high temperature and high pressure time. In this case, the controller 44 does not need to obtain the high temperature and high pressure time from the BMU 42. The controller 44 calculates the full charge capacity by using the following equation (2) obtained by transforming the equation (1).

[0100] FCC=1.0+a*CYC+c*IMP···(2)

[0101] The controller 44 corrects the impedance value according to the temperature during charging of the battery 41. The controller 44 calculates the full charge capacity by using the corrected impedance increase corresponding to the temperature. Therefore, the controller 44 can calculate the full charge capacity with high accuracy.

[0102] (Second Embodiment)

[0103] A second embodiment of the present invention is described. In the second embodiment, instead of Figure 2 The battery 40 shown uses Fig.12 Battery 40a is shown. Fig.12 An example of the structure of the battery 40a of this embodiment is shown. Figure 2 The structure shown is different from the structure shown in Figure 2, and the description of the structure that is the same as the structure shown in Figure 2 is omitted.

[0104] replace Figure 2 The battery capacity calculation device 43 shown is used Fig.12 In the battery capacity calculation device 43a, instead of Figure 2 The controller 44 is shown as controller 44a.

[0105] The controller 44a has Figure 2 The illustrated state acquisition unit 440, impedance value calculation unit 441, battery capacity calculation unit 442, memory control unit 443, and charging control unit 444 further include a life estimation unit 445. The life estimation unit 445 calculates the time until the full charge capacity of the battery 41 becomes less than a predetermined capacity.

[0106] The controller 44a executes Fig.13 The capacity calculation process shown is replaced by Figure 8 The capacity calculation process is shown. Fig.13 An example of capacity calculation processing according to this embodiment is shown. Figure 8 The processing different from that shown is omitted. Figure 8 The processing shown is the same as the processing described above.

[0107] Fig.13 Steps S200 to S203 shown are similar to Figure 8 The steps S200 to S203 shown are the same.

[0108] (Step S204)

[0109] After executing step S203, the life estimation unit 445 determines whether the full charge capacity (FCC) calculated in step S203 is less than 80%. If the full charge capacity is 80% or more, the controller 44a executes step S200. If the full charge capacity is less than 80%, the controller 44a executes the following step S205.

[0110] (Step S205)

[0111] The full charge capacity calculated in step S203 and time information indicating the date when the full charge capacity was calculated are recorded in memory 45. Life estimation unit 445 uses the full charge capacity and time information recorded in memory 45 to calculate the time until the full charge capacity reaches the reference capacity.

[0112] Fig.14 An example of time change of the full charge capacity of a battery having the same configuration as the battery 41 is shown. Fig.14 The horizontal axis of the graph in represents time, and the vertical axis represents full charge capacity.

[0113] The full charge capacity gradually decreases as time passes. The relationship between time and full charge capacity can be approximated by a straight line. On the date shown in T1, the full charge capacity is 80%. Then, on the date shown in T2, the full charge capacity is 60% of the reference capacity. The life estimation unit 445 calculates the time between T1 and T2.

[0114] Specifically, the life estimation unit 445 calculates a mathematical formula of an approximate straight line representing the relationship between time and full charge capacity by using the past full charge capacity recorded in the memory 45. The life estimation unit 445 calculates the time until the full charge capacity changes from 80% to 60% by using this mathematical formula. This time is a reference for when the user replaces the battery 41. The life estimation unit 445 may also calculate the number of cycles corresponding to this time.

[0115] In the above example, the threshold value in step S204 is 80%, but the threshold value may be a value other than 80%. In the above example, the reference capacity is 60%, but the reference capacity may be a value other than 60%.

[0116] The time calculated by the life estimation unit 445 may be output to the CPU 11. The CPU 11 may also perform a notification process for notifying the user of the time. For example, the CPU 11 may display information indicating the time on the display unit 14. The CPU 11 may also display the information indicating the time on the display unit 14. Figure 1 The speaker (not shown) generates a sound corresponding to the information. The CPU 11 may also send the information to other devices via the WLAN card 25.

[0117] As described above, the controller 44 records the calculated full charge capacity and the time information of the time when the full charge capacity is calculated in the memory 45. The controller 44 calculates the time until the full charge capacity of the battery 41 becomes less than the predetermined capacity by using the full charge capacity and the time information recorded in the memory 45. The controller 44 can predict the life of the battery 41.

[0118] As mentioned above, although the embodiment of the present invention is described in detail with reference to the drawings, the specific structure is not limited to the above-mentioned embodiment, and design changes and the like that do not depart from the scope of the gist of the present invention are also included.

Claims

1. A battery capacity calculation device, wherein: The battery capacity calculation device comprises a controller, The controller obtains a first voltage value and a charging current value of the battery during charging of the battery. obtaining a second voltage value of the battery during a pause in charging of the battery, calculating the impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value, calculating the ratio of the impedance value to the initial impedance value pre-recorded in the memory, that is, the impedance increase, Obtain the cycle number of the battery, The time when the temperature of the battery is within a predetermined temperature range and the output voltage value of the battery is within a predetermined voltage range is obtained, A full charge capacity of the battery is calculated by using the cycle number, the impedance increase, and the time.

2. The battery capacity calculation device according to claim 1, wherein: The controller calculates the full charge capacity according to the mathematical formula FCC=1.0+a*CYC+b*HTVT+c*IMP. In the mathematical formula, FCC is the full charge capacity, CYC is the number of cycles, HTVT is the time, IMP is the impedance increase, and a, b, and c are predetermined coefficients.

3. The battery capacity calculation device according to claim 1 or 2, wherein: The controller corrects the impedance value according to the temperature during charging of the battery.

4. The battery capacity calculation device according to claim 1 or 2, wherein: The controller records the calculated full charge capacity and time information of the time when the full charge capacity is calculated in a memory, By using the full charge capacity and the time information recorded in the memory, the time until the full charge capacity of the battery becomes equal to or less than a predetermined capacity is calculated.

5. A battery capacity calculation device, wherein: The battery capacity calculation device comprises a controller, The controller obtains a first voltage value and a charging current value of the battery during charging of the battery. obtaining a second voltage value of the battery during a pause in charging of the battery, calculating the impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value, calculating the ratio of the impedance value to the initial impedance value pre-recorded in the memory, that is, the impedance increase, Obtain the cycle number of the battery, The full charge capacity of the battery is calculated by using the cycle number and the impedance increase.

6. A method for calculating battery capacity, comprising: The step of obtaining a first voltage value and a charging current value of the battery during charging of the battery; The step of obtaining a second voltage value of the battery when charging of the battery is suspended; a step of calculating an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value; The step of calculating the ratio of the impedance value to the initial impedance value pre-recorded in the memory, that is, the impedance increase; A step of obtaining the cycle number of the battery; A step of obtaining a time when the temperature of the battery is within a prescribed temperature range and the output voltage value of the battery is within a prescribed voltage range; as well as a step of calculating a full charge capacity of the battery by using the cycle number, the impedance increase, and the time.

7. A method for calculating battery capacity, comprising: The step of obtaining a first voltage value and a charging current value of the battery during charging of the battery; The step of obtaining a second voltage value of the battery when charging of the battery is suspended; a step of calculating an impedance value of the battery by using the first voltage value, the second voltage value, and the charging current value; The step of calculating the ratio of the impedance value to the initial impedance value pre-recorded in the memory, that is, the impedance increase; A step of obtaining the cycle number of the battery; and a step of calculating a full charge capacity of the battery by using the cycle number and the impedance increase.

Images