Battery capacity estimation methods, battery modules and their electrical products
By measuring the open-circuit voltage of a lithium-ion battery in a resting state and combining it with formula calculations, the problem of difficulty in updating the full-charge capacity (FCC) of lithium-ion batteries was solved, enabling accurate updating of the FCC in a resting state and improving the accuracy of the state of charge (SOC).
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SIMPLO TECH COMPANY
- Filing Date
- 2022-09-02
- Publication Date
- 2026-06-30
AI Technical Summary
In existing technologies, the full charge capacity (FCC) of lithium-ion batteries is difficult to update frequently, especially when end users do not easily perform deep discharge of the battery or do not meet the conditions for continuous discharge, resulting in low accuracy of the state of charge (SOC).
By measuring the open-circuit voltage of the battery in a resting state, and combining it with stored open-circuit voltage information and rated capacity, the inherent capacity and saturated capacity of the battery are calculated using formulas, and the saturated capacity FCC is updated, even under conditions where continuous discharge has not been achieved.
It enables frequent updates of the full charge capacity (FCC) of lithium-ion batteries without requiring full charge and discharge, improving the accuracy of the state of charge (SOC). It is suitable for various temperature and current conditions and for various electronic devices.
Smart Images
Figure CN117269799B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a capacity estimation method, a battery module, and an electrical product, and more particularly to a capacity estimation method, a battery module, and an electrical product that measures an open-circuit voltage of a battery after it has been charged to a fully charged state for a preset period, and then uses the open-circuit voltage to determine the inherent capacity. Background Technology
[0002] Lithium-ion batteries are widely used in many 3C products. These products typically inform end users of the remaining percentage of the battery's State of Charge (SOC), allowing them to roughly know how much of the battery is still usable and prepare accordingly. The State of Charge is calculated as the percentage of the battery's remaining capacity (RC) to its full charge capacity (FCC, or Full Charge Capacity). Therefore, the full charge capacity (FCC) is a crucial factor in determining the accuracy of the SOC.
[0003] Most battery capacity algorithms on the market generally use a lookup table to update the full charge capacity (FCC). This method essentially works by using a pre-established voltage point representing the remaining percentage of the absolute state of charge (SOC) (typically 9% or 6%) as a forced voltage correction point. The battery is continuously discharged from its full charge (FC) state (or fully charged state) until the battery voltage falls below the forced voltage correction point. At this point, the SOC is forcibly corrected to the corresponding remaining percentage, and the FCC is updated simultaneously.
[0004] Based on typical end-user habits, this method faces two difficulties that prevent the FCC (Fuel Capacity Correction Code) from updating for an extended period. First, end-users are unlikely to discharge the battery to such a deep state. Second, continuous discharge is required before the battery is discharged from its full charge to the forced voltage correction point. If the end-user recharges the battery before reaching the forced voltage correction point, the FCC will not update. Therefore, a novel method for estimating the FCC is needed to improve the display of the remaining battery percentage. Summary of the Invention
[0005] According to one embodiment of the present invention, a capacity estimation method is provided that can update the saturated capacity even if the condition of continuous discharge is not met. In one embodiment, for a battery that has been continuously connected to a power source for a preset period and is in a resting state, an open-circuit voltage of the battery is measured, and then at least one saturated capacity of the battery is obtained using the open-circuit voltage.
[0006] According to an embodiment of the present invention, a capacity estimation method is provided, applied to a battery module including a battery and a control system, for detecting the battery of the battery module. The control system includes a detection unit, a storage unit, and a processing unit. The storage unit stores open-circuit voltage information and multiple rated capacities. The open-circuit voltage information includes open-circuit voltmeters or functions corresponding to multiple different temperatures. The capacity estimation method includes the following steps: when the processing unit determines that the battery has been charged to a fully charged state for a preset period and enters a resting state, the detection unit measures an open-circuit voltage and a temperature of the battery. The processing unit uses the measured open-circuit voltage of the battery and, according to the open-circuit voltmeter or function of the battery at the specified temperature, obtains a state of charge (SOC) of the battery. Using the multiple rated capacities and the temperature, the rated capacity corresponding to the temperature is obtained. And, the processing unit uses the rated capacity corresponding to the temperature and the SOC to calculate an inherent capacity of the battery.
[0007] In one embodiment, preferably, the plurality of rated capacities are a plurality of battery capacities that vary with different temperatures at a preset discharge rate, and the inherent capacity is the battery capacity at that temperature and the preset discharge rate.
[0008] In one embodiment, the inherent capacity is obtained using the following formula (1).
[0009] Formula (1): Q T =Design Capacity T ×SOC%, where T represents the temperature, Q T This indicates the inherent capacity, or Design Capacity. T This indicates the rated capacity corresponding to the temperature and the preset discharge rate, while SOC indicates the state of charge.
[0010] In one embodiment, the state of charge is added to a depth of discharge to 100%, and the inherent capacity is obtained using the following formula (2).
[0011] Formula (2): Q T =Design Capacity T ×(1–DOD%), where T represents the temperature, Q T This indicates the inherent capacity, or Design Capacity. T This indicates the rated capacity corresponding to the temperature and the preset discharge rate, while DOD indicates the depth of discharge.
[0012] In one embodiment, the storage unit further stores saturated capacity offset information. The capacity estimation method further includes: the processing unit using the inherent capacity to obtain an inherent maximum capacity of the battery. The aforementioned steps include: the processing unit using the saturated capacity offset information to obtain a first saturated capacity offset corresponding to a preset discharge rate and the temperature, and using the inherent capacity and the first saturated capacity offset to obtain the inherent maximum capacity of the battery.
[0013] In one embodiment, the step of the processing unit obtaining an inherent maximum capacity of the battery using the inherent capacity further includes: the processing unit obtaining a second saturated capacity offset corresponding to the temperature and a discharge rate using the saturated capacity offset information; and obtaining the saturated capacity using the inherent maximum capacity and the second saturated capacity offset. Wherein, the saturated capacity is the battery capacity at the temperature and the discharge rate.
[0014] In one embodiment, the inherent maximum capacity of the battery is obtained by using the following formula (3).
[0015] Formula (3): Q Max =Q T +FCC Offset PC,T , where Q Max This indicates the inherent maximum capacity, PC indicates the preset discharge rate, and FCC Offset. PC,T This indicates the offset of the first saturated capacity.
[0016] In one embodiment, the saturation capacity is obtained using the following formula (4).
[0017] Formula (4): FCC C-Rate,T =Q Max -FCC Offset C-Rate,T Among them, FCC C-Rate,T This indicates the saturated capacity at that discharge rate and temperature, FCC Offset. C-Rate,T This indicates the offset of the second saturated capacity.
[0018] In one embodiment, the resting state is a state in which there is no charging or discharging current.
[0019] In one embodiment, the saturation capacity offset information is a saturation capacity offset table or function actually obtained experimentally based on multiple currents and multiple temperatures.
[0020] According to one embodiment of the present invention, an electrical product is provided, comprising an electronic device and a battery module. The battery module is connected to the electronic device and includes a battery and a control system, wherein the control system detects the battery using a capacity estimation method according to the preceding paragraph.
[0021] According to one embodiment of the present invention, a battery module is provided, connected to an electronic device. The battery module includes a battery and a control system. The control system includes a detection unit, a storage unit, and a processing unit. The detection unit is used to measure computational data of the battery. The storage unit stores at least one open-circuit voltage information, multiple rated capacities, and saturated capacity offset information. The open-circuit voltage information includes an open-circuit voltmeter or function at any temperature. The processing unit is used to calculate multiple computational data. The control system detects the battery using the capacity estimation method described in the preceding paragraphs of the embodiments.
[0022] In summary, according to an embodiment of the present invention, a method can be provided for measuring the open-circuit voltage of a battery that has been continuously connected to a power source for a preset period and is now in a resting state, and then using this open-circuit voltage to determine the battery's full-charge capacity. Therefore, even if the conditions for continuous discharge are not met, the full-charge capacity (FCC) can be updated more frequently. Attached Figure Description
[0023] Figure 1 This diagram shows a functional block diagram of an electrical product according to an embodiment of the present invention.
[0024] Figure 2A This diagram shows the relationship between the number of battery cycles and the open-circuit voltage in a fully charged state according to an embodiment of the present invention.
[0025] Figure 2B A graph showing the relationship between the depth of discharge and the open-circuit voltage in a fully charged state of a battery according to an embodiment of the present invention.
[0026] Figure 3 This diagram illustrates the relationship between the inherent capacity and the rated capacity of an embodiment of the present invention.
[0027] Figure 4 A schematic diagram showing the inherent maximum capacity, multiple saturated capacities, and saturated capacity offset table of an embodiment of the present invention.
[0028] Figure 5 This diagram shows a saturation capacity offset table according to an embodiment of the present invention.
[0029] Figure 6A A graph showing the relationship between the estimated saturated capacity and the actual saturated capacity of the battery module under different loads at 0℃.
[0030] Figure 6B A graph showing the relationship between the estimated full-charge capacity and the actual full-charge capacity of the battery module under different loads at 25°C.
[0031] Figure 6C A graph showing the relationship between the estimated full-charge capacity and the actual full-charge capacity of the battery module under different loads at 40℃.
[0032] Figure 6D This graph shows the relationship between the estimated saturated capacity and the actual saturated capacity during the battery module cycle aging test at 25℃.
[0033] Figure 6E This graph shows the relationship between the estimated saturated capacity and the actual saturated capacity during the battery module cycle aging test at 40℃.
[0034] Figure 7 This is a flowchart illustrating the execution of a capacitance estimation method according to an embodiment of the present invention.
[0035] Figure Labels
[0036] 100: Electrical appliances
[0037] 101: Electronic Devices
[0038] 300: Battery Module
[0039] 310: Battery
[0040] 311: Battery Cell
[0041] 320: Control System
[0042] 321: Storage Unit
[0043] 322: Detection Unit
[0044] 323: Processing Unit
[0045] S01~S08: Steps in the Capacity Estimation Method Detailed Implementation
[0046] Figure 1 This diagram shows a functional block diagram of an electrical product 100 according to an embodiment of the present invention. The electrical product 100 includes a battery module 300 and an electronic device 101. The capacity estimation method according to an embodiment of the present invention can be applied to the battery module 300. Figure 1As shown, the battery module 300 is connected to the electronic device 101 and includes a battery 310 and a control system 320. The battery 310 includes at least one cell 311 electrically connected to each other. The control system 320 is capable of executing the aforementioned capacity estimation method and includes a storage unit 321, a detection unit 322, and a processing unit 323. The storage unit 321 can be, for example, a memory used to store various computational data, such as data for looking up tables or functions. The detection unit 322 is connected to the cell 311 of the battery 310 to obtain battery information such as temperature and voltage of the cell 311. The processing unit 323 obtains the data required for the capacity estimation method from the storage unit 321 and the detection unit 322 to estimate the inherent capacity Q of the battery 310. T Or the full charge capacity (FCC). Furthermore, those skilled in the art can determine the structure of the battery 310 and the control system 320 based on the disclosure of this invention, the characteristics of the circuit elements used in implementing this invention, and / or the desired effect in implementing this invention. Moreover, those skilled in the art can equally modify the implementation of this invention based on the foregoing disclosure. The battery capacity estimation method of this invention will be described in more detail below. The electrical product 100 can be, for example, a 3C product such as a laptop computer, mobile phone, or camera; or a product such as automotive electronics.
[0047] When end users use electrical products 100 (such as 3C products) that include an electronic device 101 and a battery module 300 that are electrically connected to each other, they often use the electrical product 100 while it is being charged by a charger. Once the charger has fully charged the battery module 300, it stops charging it. At this time, all the power consumption of the electrical product 100 is provided by the charger, not by the battery 310, and the battery 310 enters a resting state with no charging or discharging current. If the battery 310, in its resting state, is continuously connected to the power source for a preset period, it will enter an open-circuit state. Based on the aforementioned user habits, research has shown that by utilizing the user's habit of not immediately removing the charger after fully charging the battery 310, the inherent capacity Q of the battery 310 can be estimated using the characteristic of the open-circuit state of the battery 310 corresponding to the state of charge (SOC). T Or, the FCC could use full charge capacity as a way to solve the problems encountered by known technologies.
[0048] According to one embodiment of the present invention, the aim is to utilize a more practical method, in line with the usage habits of end users who often keep the battery connected to the charger for extended periods, to estimate the inherent capacity Q of the lithium-ion battery 310 when it is fully charged at any temperature without requiring a complete charge-discharge cycle. T Alternatively, the full charge capacity (FCC) can be used. In one embodiment, the full charge capacity (FCC) can be updated more frequently.
[0049] The State of Charge (SOC) of a lithium-ion battery reflects its remaining capacity. The Depth of Discharge (DOD) is defined as the percentage of capacity discharged from a fully charged state relative to the Full Charge Capacity (FCC). In other words, the SOC and DOD are added together to equal 100%. Therefore, DOD and SOC are complementary.
[0050] Lithium-ion batteries have the characteristic that, at the same temperature, the open circuit voltage (OCV) corresponds to a unique state of charge (SOC) value. Lithium-ion batteries at different temperatures exhibit different open circuit voltage curves. In practical applications, the relationship curve between open circuit voltage (OCV) and SOC can be pre-stored using a lookup table or function. The capacity obtained by continuously discharging a brand-new lithium-ion battery 310 from its fully charged state at a preset discharge rate (PC, e.g., 0.2C) at any temperature is called the design capacity (DC) for that temperature.
[0051] Due to their characteristics, lithium-ion batteries exhibit varying discharge capacities at different temperatures and discharge currents. In one embodiment, a plurality of rated capacities are stored in the storage unit 321 of the control system 320. Preferably, the plurality of rated capacities DC represent multiple battery capacities that vary with different temperatures at a preset discharge rate.
[0052] The internal resistance of the lithium-ion battery 310 increases with the number of battery cycles. Therefore, due to the increased internal resistance with increasing cycle count, the battery 310 exhibits a smaller open-circuit voltage (OCV) value when fully charged under the same conditions for determining full charge (full charge condition). This decrease in OCV value follows a curve, such as... Figure 2A and Figure 2B As shown. Therefore, this characteristic can be used to obtain the state of charge of cell 311 by using the open-circuit voltage OCV value when fully charged. Figure 3 This diagram illustrates the relationship between the inherent capacity and the rated capacity of an embodiment of the present invention. (The following is a continuation of the previous paragraph.) Figure 3As shown, the inherent capacity of battery 310 can be estimated using the state of charge and rated capacity DC. It can also be seen that the internal resistance increases with the number of cycles, causing the open-circuit voltage to decrease; that is, the open-circuit voltage of battery 310 in its state of full charge gradually decreases with the number of cycles. This concept can also be considered as the State of Health (SOH), and in one embodiment, the open-circuit voltage OCV in the state of full charge can be used as a reference indicator of the battery's state of health. In one embodiment, since the open-circuit voltage OCV in the state of full charge and the reference indicator of the battery's state of health have a predetermined relationship, the reference indicator of the battery's state of health (SOH) can be a function of the open-circuit voltage OCV in the state of full charge. As described above, according to an embodiment of the present invention, the reference indicator of the battery's state of health can be obtained based on the open-circuit voltage of battery 310 in its state of full charge.
[0053] Full Charge Capacity (FCC) is defined as the capacity that the battery 310 can release when continuously discharged from its fully charged state at any current and temperature. In one embodiment, the internal mechanisms of the control system 320 of the battery module 300 operate based on the FCC. For example, the State of Charge (SOC) is calculated based on the FCC. Therefore, the accuracy of the FCC is a crucial factor in determining the accuracy of the SOC.
[0054] Figure 4 A schematic diagram showing the inherent maximum capacity, multiple saturated capacities, and saturated capacity offset table according to an embodiment of the present invention is provided. Figure 4 As shown, in order to accurately estimate and update the saturated capacity FCC under different currents and temperatures, a new variable is introduced in one embodiment of the present invention: the inherent maximum capacity Q. Max It is defined as the maximum usable capacity of battery 310. In other words, if the current or temperature changes, but the inherent discharge capacity of battery 310 does not change, i.e., the full charge capacity FCC changes, the inherent maximum capacity Q remains the same. Max It will not change. Assume an inherent maximum capacity Q. Max There is an offset between the saturated capacity (FCC) and the full charge capacity (FCC), where the offset varies with current and temperature; this offset is named the saturated capacity offset (FCC Offset). Therefore, the inherent maximum capacity Q can be obtained from the full charge capacity (FCC). Max The full charge capacity FCC can be calculated using the following formula (4).
[0055] FCC C-Rate,T =Q Max -FCC Offset C-Rate,T Formula (4)
[0056] Here, C-Rate refers to a discharge rate, T refers to temperature, and "C-Rate,T" refers to both the discharge rate and the temperature. Figure 4 The paper exemplarily shows the relationship between the saturated capacity offset (FCC Offset) and the saturated capacity (FCC) when the discharge rate is 0.2C at 0℃, the discharge rate is 0.2C at 25℃, and the discharge rate is 0.5C at 25℃.
[0057] Figure 5 This is an example of an FCC Offset Table. In this example, the vertical axis uses two currents (C1 and C2) as boundaries, and the horizontal axis uses two temperatures (T1 and T2) as boundaries, dividing the current and temperature into three regions each. For example, FCC Offset 0 refers to the region where the temperature is below FCC Offset T1 and the current is below FCC Offset C1, and FCC Offset 8 refers to the region where the temperature is above FCC Offset T2 and the current is above FCC Offset C2. In practical applications, the FCC Offset needs to be pre-stored in the storage unit 321 of the control system 320 using a lookup table. In this embodiment, although the FCC Offset information is illustrated using a FCC Offset Table as an example, other embodiments may also use the corresponding FCC Offset Table. Figure 5 The data is converted into a function and stored in storage unit 321 as saturated capacity offset information.
[0058] In one embodiment, the inherent maximum capacity Q can be connected using the above-mentioned saturated capacity offset table or function. Max The relationship between the full charge capacity (FCC) and the full charge capacity (FCC) is such that when calculating the full charge capacity (FCC) for any current and temperature range, this full charge capacity offset table can be used; or the full charge capacity offset corresponding to any temperature and any discharge rate can be obtained by using the function converted from the multiple data, and then used to update the full charge capacity (FCC) for any current and temperature range.
[0059] Inherent maximum capacity Q Max The FCC Offset is a battery-dependent parameter, meaning that each type of battery 310 has a different parameter, and therefore it can be obtained experimentally. Figure 5Using the FCCOffset Table as an example, the battery 310 is continuously discharged from its fully charged state to the cutoff voltage in nine combinations across three current and three temperature regions. This yields the actual discharge capacity of the battery 310 in each region. A total of nine sets of actual discharge capacities can be obtained. The largest of these nine sets is multiplied by a hypothetical fixed rate to obtain the initial inherent maximum capacity Q. Max Finally, the inherent maximum capacity Q is... Max By subtracting each of the nine actual discharge capacities, the following can be obtained: Figure 5 The nine sets of saturated capacity offsets (FCC Offsets) are shown.
[0060] [Example]
[0061] Figure 7 This is a flowchart illustrating the execution of a capacitance estimation method according to an embodiment of the present invention. Figure 7 As shown, for battery 310 at any ambient temperature, the specific implementation method is as follows:
[0062] Step S01: Pre-build tables to obtain the rated capacity DC of the new battery 310 at various temperatures, the open circuit voltage table (OCV Table) for multiple different battery temperatures, and the full charge capacity offset table (FCC Offset Table).
[0063] Step S02: Place the battery 310 in any ambient temperature.
[0064] Step S03: Charge the battery 310 to full charge for a preset period, such as 30 minutes, and then put it into a resting state.
[0065] Step S04: When the processing unit 323 determines that the battery 310 has been charged to a fully charged state for a preset period and enters a resting state, the detection unit 322 measures the open circuit voltage OCV and battery temperature of the battery 310 at this time.
[0066] Step S05: Using the measured open-circuit voltage OCV, the corresponding state of charge (SOC) of battery 310 at this time is obtained by consulting the open-circuit voltage table (OCVTable) corresponding to the battery temperature.
[0067] Step S06: Using the following formula (1), the inherent capacity Q of battery 310 at any temperature and a discharge rate of 0.2C can be estimated. T .
[0068] Formula (1): Q T =Design Capacity T ×SOC%,
[0069] Where T represents the battery temperature, Q T Indicates inherent capacity, Design Capacity T This indicates the rated capacity corresponding to the battery temperature and preset discharge rate, while SOC indicates the state of charge.
[0070] In one embodiment, step S06 may also be to estimate the inherent capacity Q of battery 310 at any temperature and a discharge rate of 0.2C using the following formula (2). T .
[0071] Formula (2): Q T =Design Capacity T ×(1–DOD%),
[0072] Where T represents the battery temperature, Q T Indicates inherent capacity, Design Capacity T This indicates the rated capacity corresponding to the battery temperature and preset discharge rate, while DOD indicates the depth of discharge. The state of charge and the depth of discharge are added together to 100%.
[0073] Step S07: Using the following formula (3), the inherent maximum capacity Q of battery 310 at any temperature can be estimated from the inherent capacity at 0.2C and the offset of the first saturated capacity (FCC Offset). Max .
[0074] Formula (3): Q Max =Q T +FCC Offset PC,T ,
[0075] Among them, Q Max Indicates the inherent maximum capacity, PC indicates the preset discharge rate, and FCC Offset. PC,T This represents the first saturation capacity offset, which is related to the preset discharge rate and the arbitrary temperature.
[0076] Step S08: Using the following formula (4), the inherent maximum capacity Q can be obtained. Max The discharge capacity of battery 310 at any current and temperature is estimated by using the second full-charge capacity offset (FCCOffset), i.e., the full-charge capacity FCC.
[0077] Formula (4): FCC C-Rate,T =Q Max -FCC Offset C-Rate,T ,
[0078] Among them, FCC C-Rate,TThe FCC Offset represents the saturated capacity at the specified discharge rate and temperature. C-Rate,T This represents the second saturation capacity offset, which is related to the discharge rate and the temperature.
[0079] The above formulas use 0.2C as the preset discharge rate and 25°C as the preset temperature as examples. However, in other embodiments, other values can be designed to meet the needs of various products and environments.
[0080] The following are the experimental verification results of battery module 300 under different temperatures and loads. The test steps are as follows:
[0081] 1. Place the 310 battery at an ambient temperature of 0℃, 25℃, or 40℃ respectively.
[0082] 2. Charge battery 310 until it is fully charged.
[0083] 3. Rest for 30 minutes to obtain an estimated full charge capacity.
[0084] 4. At the three different temperatures mentioned above, the battery 310 was discharged to 3V with a load of 10%, 50% or 100% of the continuous maximum discharge power of the battery 310, respectively, to obtain the actual full-charge capacity of the battery 310. Nine experimental results can be obtained.
[0085] That Figure 6A , Figure 6B and Figure 6C To compare the estimated saturated capacity with the accurate value of the actual saturated capacity, a graph is plotted where the horizontal axis represents discharge power and the vertical axis represents error, as shown below. Figure 6A , Figure 6B , Figure 6C As shown, the capacity estimation method of the present invention can be used to predict the discharge capacity of battery module 300 under different temperatures and loads with a certain degree of accuracy, and the error range can be controlled within 3%.
[0086] The following are the cycle aging verification results of battery module 300 at different temperatures. The test steps are as follows:
[0087] 1. Place the battery 310 in an ambient temperature of 25℃ or 40℃ respectively.
[0088] 2. Charge battery 310 until it is fully charged.
[0089] 3. Rest for 20 minutes to obtain an estimated full charge capacity.
[0090] 4. Discharge battery 310 to 3V with a load of 50% of its continuous maximum discharge power to obtain the actual battery capacity of battery 310.
[0091] 5. Take a 20-minute break.
[0092] 6. Repeat the above steps.
[0093] Battery modules Pack#A, Pack#B, Pack#C, and Pack#D are battery modules with the same conditions. Figure 6D The experimental results for battery module Pack#A and battery module Pack#B at 25℃ are presented. Figure 6E The experimental results are shown for battery module Pack#C and battery module Pack#D at 40℃, respectively. Figure 6D and Figure 6E To compare the estimated saturated capacity with the accurate value of the actual saturated capacity, a graph is plotted, where the horizontal axis represents the cycle count and the vertical axis represents the error. Figure 6D and Figure 6E It can be seen that by using the capacity estimation method of the present invention, the calculation accuracy error of the discharge capacity of the cycle-aged battery can be controlled within 3% when detecting the discharge capacity at different temperatures.
[0094] In summary, according to an embodiment of the present invention, a capacity estimation method for updating the full-charge capacity (FCC) can be provided even when continuous discharge conditions are not met. This method leverages the end-user's habit of keeping the battery connected to the charger for extended periods, allowing for the estimation of the FCC of the lithium-ion battery 310 without fully charging and discharging it, thus enabling frequent updates to the FCC. Since the open-circuit voltage (OCV) value in the state of full charge implicitly contains the concept of the battery's state of health (SOH), this method is also effective in estimating the full-charge capacity of aging batteries. In one embodiment, the inherent capacity Q can also be estimated simultaneously. T Alternatively, the full charge capacity (FCC) can be used by the electronic device 101 to perform actual electrical-related calculations. In one embodiment, the full charge capacity (FCC) of the lithium-ion battery 310 can also be estimated when the battery 310 is fully charged at any temperature.
Claims
1. A capacitance estimation method, characterized in that, An application is made to a battery module comprising a battery and a control system, for detecting the battery in the battery module, wherein... The control system includes a detection unit, a storage unit, and a processing unit. The storage unit stores open-circuit voltage information and multiple rated capacities. The open-circuit voltage information includes open-circuit voltage tables or functions corresponding to multiple different temperatures. The capacitance estimation method includes: When the processing unit determines that the battery has been charged to a fully charged state for a preset period and enters a resting state, the detection unit measures an open-circuit voltage and a temperature of the battery; the resting state is a state in which there is no charging or discharging current. The processing unit uses the measured open-circuit voltage of the battery to obtain a state of charge of the battery according to the open-circuit voltmeter or function at the temperature of the battery. Using the plurality of rated capacities and the temperature, a rated capacity corresponding to the temperature is obtained, wherein the plurality of rated capacities are multiple battery capacities that vary with different temperatures at a preset discharge rate; and The processing unit uses the rated capacity corresponding to the temperature and the state of charge to determine an inherent capacity of the battery.
2. The capacitance estimation method according to claim 1, characterized in that, The inherent capacity is the battery capacity at the specified temperature and the preset discharge rate.
3. The capacitance estimation method according to claim 1, characterized in that, The inherent capacity is obtained using the following formula 1. Formula 1: Q T = Design Capacity T × SOC%, where T represents the temperature, Q T Indicates the inherent capacity, Design Capacity T The rated capacity corresponds to the temperature and a preset discharge rate, while SOC represents the state of charge.
4. The capacitance estimation method according to claim 1, characterized in that, The state of charge plus a depth of discharge equals 100%, and The inherent capacity is obtained using the following formula 2. Formula 2: Q T = Design Capacity T × (1–DOD%), where T represents the temperature, Q T Indicates the inherent capacity, Design Capacity T The rated capacity corresponds to the stated temperature and a preset discharge rate, while DOD represents the depth of discharge.
5. The capacitance estimation method according to any one of claims 1 to 4, characterized in that, Based on the open-circuit voltage of the battery when it is fully charged, a health status reference index of the battery is obtained.
6. The capacitance estimation method according to claim 3 or 4, characterized in that, The storage unit further stores saturation capacity offset information. The capacitance estimation method further includes: The processing unit uses the inherent capacity to determine an inherent maximum capacity of the battery, which includes: The processing unit uses the saturated capacity offset information to obtain a first saturated capacity offset corresponding to the preset discharge rate and the temperature, and uses the inherent capacity and the first saturated capacity offset to obtain the inherent maximum capacity of the battery.
7. The capacitance estimation method according to claim 6, characterized in that, The step of the processing unit determining an inherent maximum capacity of the battery using the inherent capacity further includes: The processing unit uses the saturation capacity offset information to obtain a second saturation capacity offset corresponding to the temperature and a discharge rate; and uses the inherent maximum capacity and the second saturation capacity offset to obtain the saturation capacity. Wherein, the saturated capacity is the battery capacity at the stated temperature and the stated discharge rate.
8. The capacitance estimation method according to claim 6, characterized in that, The inherent maximum capacity of the battery is obtained using the following formula 3. Formula 3: Q Max = Q T + FCC Offset PC, T , where Q Max The inherent maximum capacity is represented by PC, the preset discharge rate is represented by FCC Offset. PC, T This represents the offset of the first saturated capacity.
9. The capacitance estimation method according to claim 7, characterized in that, The saturated capacity is obtained using the following formula 4. Formula 4: FCC C-Rate, T = Q Max - FCC Offset C-Rate, T Among them, FCC C-Rate, T The FCC Offset represents the saturated capacity at the specified discharge rate and temperature. C-Rate, T This represents the offset of the second saturated capacity.
10. The capacitance estimation method according to claim 6, characterized in that, The saturation capacity offset information is a table or function of saturation capacity offset obtained experimentally based on multiple currents and multiple temperatures.
11. An electrical appliance, characterized in that, Include: An electronic device; and A battery module is connected to the electronic device and includes a battery and a control system, wherein the control system detects the battery using the capacity estimation method according to any one of claims 1 to 10.
12. A battery module, characterized in that, Connected to an electronic device, the battery module includes a battery and a control system, wherein the control system includes: A detection unit is used to measure the computational data of the battery; A storage unit stores at least one open-circuit voltage information and multiple rated capacities, wherein the open-circuit voltage information includes an open-circuit voltmeter or function at any temperature; and, A processing unit used to calculate multiple computational data; The control system uses the capacity estimation method according to any one of claims 1 to 10 to detect the battery.