Lithium battery health degree calculation method, device and equipment, control circuit of lithium battery health degree calculation equipment and medium

Abstract

The invention relates to the technical field of lithium batteries, in particular to a lithium battery health degree calculation method, device and equipment and a control circuit and medium thereof. The method comprises the following steps: when it is monitored that a battery is in a standing state, obtaining a previous state before the battery is in the standing state and an initial voltage at a current moment; acquiring a target voltage according to the previous state, acquiring a target moment when the battery reaches the target voltage, and acquiring an estimated voltage according to a time difference between the current moment and the target moment and the initial voltage; when the estimated voltage meets a preset requirement, taking the estimated voltage as an open-circuit voltage, and obtaining a theoretical residual capacity corresponding to the open-circuit voltage; obtaining a capacity difference value of two theoretical residual capacities of the battery in the standing state for two times; and acquiring the current integral electric quantity of the battery between the two standing states, and acquiring the health degree of the battery based on the current integral electric quantity and the capacity difference value. According to the invention, the estimation condition of the health degree of the battery is simplified, the estimation difficulty is reduced, and the estimation accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the field of lithium battery technology, and in particular to a lithium battery health calculation method, device, equipment, and a control circuit and medium thereof. Background Art

[0002] The battery's state of health (SOH) will affect the actual storage capacity of the energy storage device. Therefore, obtaining accurate SOH is very important for energy storage devices. Currently, the commonly used SOH estimation methods include empirical method, capacity test method and internal resistance estimation method.

[0003] The empirical method is a method of calculating battery capacity loss by considering factors such as the number of cycles, overcharge times, over-discharge times, etc. The empirical method is affected by the consistency of lithium batteries and it is difficult to fully consider all influencing factors, which will lead to inaccurate estimation results.

[0004] The capacity test method is to evaluate the health of the battery by comparing the amount of electricity required to fully charge the battery from a fully discharged state to the battery's designed capacity. This method requires testing under specific conditions, such as standing for 2 hours before charging and 2 hours after charging at room temperature. However, it is difficult to achieve the test conditions under actual working conditions, and the test time is too long.

[0005] The internal resistance estimation method uses mathematical models such as the Kalman filter algorithm and the least squares method to estimate the internal resistance of the battery, and infers the health of the battery based on the change in internal resistance and the relationship between internal resistance and health. However, this method is difficult to implement because it requires a larger MCU (Microcontroller Unit) space and is costly. Summary of the invention

[0006] The technical problem to be solved by the embodiments of the present invention is to provide a lithium battery health calculation method, device, equipment and its control circuit and medium.

[0007] The present invention discloses a method for calculating the health of a lithium battery, comprising:

[0008] Monitoring the battery state, and when it is detected that the battery is in a static state, obtaining the previous state of the battery before the static state and the initial voltage at the current moment;

[0009] Acquire a target voltage according to the previous state, acquire a target time when the battery reaches the target voltage, and acquire an estimated voltage according to a time difference between the current time and the target time and the initial voltage;

[0010] When the estimated voltage meets the preset requirement, taking the estimated voltage as the open circuit voltage, and obtaining the theoretical remaining capacity corresponding to the open circuit voltage;

[0011] Obtaining a capacity difference between two theoretical remaining capacities of the battery in the static state twice;

[0012] The current integrated capacity of the battery between the two static states is obtained, and the battery health is obtained based on the current integrated capacity and the capacity difference.

[0013] Optionally, the step of acquiring the target voltage according to the previous state includes:

[0014] When the previous state is a charging state, the target voltage is the initial voltage minus n mV;

[0015] When the previous state is a discharge state, the target voltage is the initial voltage plus nmV;

[0016] Here, n is a value greater than 0.

[0017] Optionally, the step of obtaining the estimated voltage according to the time difference between the current moment and the target moment and the initial voltage includes:

[0018] When the previous state is a charging state, the estimated voltage is obtained according to the following formula:

[0019]

[0020] When the previous state is a discharge state, the estimated voltage is obtained according to the following formula:

[0021]

[0022] Among them, U des is the estimated voltage, Δt is the time difference, U 1 is the initial voltage, and M is the preset standing time.

[0023] Optionally, the step of obtaining the estimated voltage according to the time difference between the current moment and the target moment and the initial voltage includes:

[0024] Obtaining a health calculation cycle, and determining whether the time difference exceeds the health calculation cycle, if the time difference exceeds the health calculation cycle, the time difference is valid;

[0025] If the time difference does not exceed the health calculation period, the time difference is invalid, and the step of obtaining the target time when the battery reaches the target voltage is performed again.

[0026] Optionally, when the estimated voltage meets a preset requirement, the step of using the estimated voltage as the open circuit voltage includes:

[0027] Continuously acquiring a plurality of the estimated voltages;

[0028] The difference between every two adjacent estimated voltages is calculated in time sequence, and if the differences are all smaller than a preset threshold, an average of several estimated voltages is used as the open circuit voltage.

[0029] Optionally, the step of acquiring the battery health based on the current integrated power and the capacity difference includes:

[0030] The battery health is calculated according to the following formula:

[0031]

[0032] Wherein, SOH is the battery health, ΔCAP 2 is the capacity difference, ΔCAP 0 The integrated charge of the current.

[0033] The present invention also discloses a lithium battery health calculation device, comprising:

[0034] An initial module is used to monitor the battery state, and when it is detected that the battery is in a static state, obtain the previous state of the battery before the static state and the initial voltage at the current moment;

[0035] an estimation module, configured to obtain a target voltage according to the previous state, obtain a target time when the battery reaches the target voltage, and obtain an estimated voltage according to a time difference between the current time and the target time and the initial voltage;

[0036] A capacity module, configured to use the estimated voltage as an open circuit voltage and obtain a theoretical remaining capacity corresponding to the open circuit voltage when the estimated voltage meets a preset requirement;

[0037] A difference module, used for obtaining a capacity difference between two theoretical remaining capacities of the battery in the static state twice;

[0038] The acquisition module is used to obtain the current integrated power of the battery between the two static states, and obtain the battery health based on the current integrated power and the capacity difference.

[0039] The present invention also discloses a control circuit of an energy storage device, comprising:

[0040] An input / output interface, used to charge or discharge the energy storage device;

[0041] A control chip, connected to the lithium battery pack and the input / output interface, for acquiring information from the lithium battery pack to execute the steps of the method described above;

[0042] The display circuit is connected to the control chip and is used for displaying according to the calculation result of the control chip.

[0043] The present invention also discloses a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the method described above.

[0044] The present invention also discloses an energy storage device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0045] Compared with the prior art, the beneficial effect of the lithium battery health calculation method provided by the embodiment of the present invention is that: when the battery is in a static state, the previous state of the battery before the static state and the initial voltage at the current moment are obtained, the target voltage is obtained according to the previous state, the target moment when the battery reaches the target voltage is obtained, the estimated voltage is obtained according to the time difference between the current moment and the target moment and the initial voltage, the theoretical remaining capacity corresponding to the open circuit voltage is obtained, and the capacity difference between the two theoretical remaining capacities of the battery in the static state twice is obtained; the current integrated charge of the battery between the two static states is obtained, and the battery health is obtained based on the current integrated charge and the capacity difference. The battery health can be calculated without the battery being static for a preset time under strict conditions. It only needs to monitor the voltage change and integrated charge of the battery in the static state. No complicated operation or advanced equipment is required, the estimation conditions of the battery health are simplified, no complicated algorithms are required, the estimation difficulty is reduced, and the combination of data such as the current integrated charge and the capacity difference is more in line with the actual situation of the battery itself, and the estimation accuracy is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The scheme of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which:

[0047] Figure 1 It is a flow chart of an embodiment of a method for calculating the health of a lithium battery provided by the present invention;

[0048] Figure 2 is a flow chart of another embodiment of the method for calculating the health of a lithium battery provided by the present invention;

[0049] Figure 3 It is a timing diagram of an embodiment of a method for calculating the health of a lithium battery provided by the present invention;

[0050] Figure 4 It is a structural schematic diagram of an embodiment of a lithium battery health calculation device provided by the present invention;

[0051] Figure 5 is a circuit diagram of an embodiment of a control circuit of an energy storage device provided by the present invention;

[0052] Figure 6 is a circuit diagram of an embodiment of a control chip provided by the present invention;

[0053] Figure 7 is a circuit diagram of an embodiment of a display circuit provided by the present invention;

[0054] Figure 8 It is a structural schematic diagram of an embodiment of the energy storage device provided by the present invention;

[0055] Fig. 9 It is a structural schematic diagram of an embodiment of a computer-readable storage medium provided by the present invention.

[0056] The reference numerals in the figures are:

[0057] 10. Lithium battery health calculation device; 11. Initial module; 12. Estimation module; 13. Capacity module; 14. Difference module; 15. Acquisition module; 20. Energy storage device; 21. Target battery; 22. Input and output interface; 23. Control chip; 24. Display circuit; 30. Energy storage device; 31. Processor; 32. Memory; 40. Computer-readable storage medium; 41. Computer program. DETAILED DESCRIPTION

[0058] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, the preferred embodiments of the present invention are described in detail.

[0059] See also Figure 1 , Figure 1 1 is a flow chart of an embodiment of a method for calculating the health of a lithium battery provided by the present invention. The method for calculating the health of a lithium battery provided by the present invention comprises the following steps:

[0060] S101: Monitor the battery state. When it is detected that the battery is in a static state, obtain the previous state of the battery before the static state and the initial voltage at the current moment.

[0061] In a specific implementation scenario, the battery is a battery in an energy storage device. The state of the battery is monitored, for example, the battery state can be obtained by detecting the battery current, and the battery state includes a charging state (current greater than 0), a discharging state (current less than 0) and a static state (current equal to 0). When it is monitored that the battery is in a static state, the previous state of the battery before the static state is obtained. For example, the battery is in a charging state, and when the charging is completed, the battery is no longer used, and the battery becomes a static state, then the previous state of the battery is a charging state. For another example, the battery is used after being fully charged (for example, to power a mobile device), and is no longer used after a period of time, then the previous state of the battery is a discharging state.

[0062] The moment when the battery is detected to be in the static state is taken as the current moment, that is, the moment when the battery just changes from the previous state to the static state, and the voltage of the battery at the current moment is obtained as the initial voltage.

[0063] S102: Obtain a target voltage according to a previous state, obtain a target time when the battery reaches the target voltage, and obtain an estimated voltage according to a time difference between the current time and the target time and the initial voltage.

[0064] In a specific implementation scenario, the target voltage is obtained according to the previous state. Even if the battery is in a static state, due to the influence of the previous state, the internal chemical reaction of the battery has not stopped, and the battery voltage will change slightly. The direction of this change (increase or decrease) is related to the previous state, so it is necessary to obtain the target voltage according to the previous state. If the previous state is a charging state, a voltage lower than the initial voltage is set as the target voltage. If the previous state is a discharging state, a voltage higher than the initial voltage is set as the target voltage.

[0065] This is because when the battery is turned from a charging state to a static state, the chemical reaction inside the battery is still going on, even though charging has stopped. In this case, there may be some imbalance between the positive and negative electrodes inside the battery, causing the voltage to gradually drop. When the battery is in a charging state, the chemical reaction between the positive and negative electrodes causes the chemical energy stored inside the battery to increase, and the voltage to rise. But once charging stops, the reaction inside the battery will still continue for a while, which may cause the chemical potential difference between the positive and negative electrodes to gradually decrease, causing the voltage to drop.

[0066] When the battery is turned from a discharge state to a static state, the chemical reaction inside the battery will continue, but at this time the chemical potential difference between the positive and negative electrodes inside the battery may gradually increase, causing the voltage to rise. When the battery is in a discharge state, the chemical reaction between the positive and negative electrodes causes the chemical energy stored inside the battery to gradually decrease, and the voltage decreases. However, once the discharge stops, the reaction inside the battery will continue for a period of time, which may cause the chemical potential difference between the positive and negative electrodes to gradually increase, causing the voltage to rise.

[0067] In one implementation scenario, when the previous state is the charging state, the target voltage is the initial voltage minus 1mV; when the previous state is the discharging state, the target voltage is the initial voltage plus 1mV. In other implementation scenarios, the target voltage can also be set to other values, for example, the initial voltage + / -2mV, the initial voltage + / -0.5mV, etc. The specific value is set by the user according to actual needs, and it only needs to ensure that when the previous state is the charging state, the target voltage is the initial voltage minus n mV; when the previous state is the discharging state, the target voltage is the initial voltage plus n mV; where n is a value greater than 0.

[0068] The voltage of the battery after entering the static state is monitored. Once the voltage of the battery reaches the target voltage, the time at this time is recorded as the target time. The estimated voltage is obtained based on the time difference between the current time and the target time and the initial voltage.

[0069] Lithium batteries can be equivalent to a Thevenin circuit to some extent, which is a first-order circuit composed of resistance (R) and capacitance (Λ). Under this equivalent model, the dissipation change of the polarization voltage of the battery appears as a natural exponential change in voltage. The natural exponential change means that the change in voltage decays or grows exponentially over time, rather than a simple linear change. This natural exponential change can be expanded polynomially using the Taylor formula, and for an exponential function, the Taylor expansion can usually be approximated as a quadratic function.

[0070] The general form of a quadratic function is:

[0071] f(x)=ax 2 +bx+c

[0072] Among them, a is the coefficient of the quadratic term, b is the coefficient of the linear term, and c is a constant.

[0073] Let t 1 -t 2 =Δt, the current time t 1 and initial voltage U 1 The point where it is located is the vertex, and the vertex formula of a quadratic function is:

[0074] t=a×(UU1 ) 2

[0075] In one implementation scenario, when the previous state is the charging state, the target voltage U 2 =U 1 -1. Set the target voltage U 2 =U 1 -1, and the target time t 2 Substituting this into the equation we get:

[0076] t 1 -t 2 =Δt=a×(U 1 -1-U 1 ) 2 =a×(-1) 2 =a×1=a

[0077] Substituting Δt=a into the equation, we get:

[0078] t=Δt×(UU 1 ) 2

[0079] Right now:

[0080]

[0081] The voltage measured after standing for M seconds is preset as the open circuit voltage of the battery cell, and M seconds is the characteristic data of the battery cell. The value of M can be obtained by consulting the technical specification sheet or manual of their products provided by the manufacturer. For example, M = 2h = 7200s.

[0082] Therefore, the estimated voltage is obtained according to the following formula:

[0083]

[0084] Among them, U des is the estimated voltage, Δt is the time difference, U 1 is the initial voltage, and M is the preset rest time. Since the voltage decreases when the battery is left at rest after charging, at the current time t 1 The estimated voltage U des Must be lower than U 1 ,so

[0085] In another implementation scenario, when the previous state is the discharge state, the target voltage U 2 =U 1 +1. Set the target voltage U 2 =U 1 +1, and the target time t 2 Substituting this into the equation we get:

[0086] t 1 -t 2 =Δt=a×(U 1 +1-U 1 ) 2 =a×(1) 2 =a×1=a

[0087] Substituting Δt=a into the equation, we get:

[0088] t=Δt×(UU 1 ) 2

[0089] Right now:

[0090]

[0091] The voltage measured after standing for M seconds is preset as the open circuit voltage of the battery cell, and M seconds is the characteristic data of the battery cell. The value of M can be obtained by consulting the technical specification sheet or manual of their products provided by the manufacturer. For example, M = 2h = 7200s.

[0092] Therefore, the estimated voltage is obtained according to the following formula:

[0093]

[0094] Among them, U des is the estimated voltage, Δt is the time difference, U 1 is the initial voltage, and M is the preset rest time. Since the voltage increases when the discharge state is left alone, at the current time t 1 The estimated voltage U des Must be higher than U 1 ,so

[0095] S103: When the estimated voltage meets the preset requirement, the estimated voltage is used as the open circuit voltage to obtain the theoretical remaining capacity corresponding to the open circuit voltage.

[0096] In a specific implementation scenario, requirements are set for the estimated voltage, for example, requirements are put forward for the accuracy and smoothness of the estimated voltage. When the estimated voltage meets the preset requirements, the estimated voltage is used as the open circuit voltage to obtain the theoretical remaining capacity corresponding to the open circuit voltage.

[0097] You can first fully charge the battery and then conduct a discharge test to obtain a voltage-capacity comparison table. Specifically, when the lithium battery is discharged at a specific discharge rate (0.01C), the relationship data between the voltage and the capacity is measured. These data can be approximately expressed as a "relationship table between open circuit voltage and SOC", that is, an OCV-SOC comparison table. SOC stands for the state of charge of the battery, that is, the ratio of the current charge stored in the battery to its maximum charge. OCV stands for open circuit voltage, that is, the voltage value measured when the battery has no external load.

[0098] After taking the estimated voltage as the open circuit voltage, query the OCV-SOC comparison table to obtain the SOC corresponding to the open circuit voltage, and obtain the theoretical remaining power based on the SOC.

[0099] S104: Obtaining a capacity difference between two theoretical remaining capacities of the battery in a static state twice.

[0100] In a specific implementation scenario, after executing step S103, the battery status continues to be monitored. When the battery is in a static state again after the current static state, steps S101-S103 are executed again to obtain a new theoretical remaining power. It should be noted that between two static states, at least one charging / discharging state may be included, and at least one static state may also be included. For example, a first theoretical remaining power is obtained in the first static state of the battery, and then the battery status is continuously monitored. After the battery is in a charging state, it is in a static state again, and the second theoretical remaining power in the second static state is obtained. The difference between the first theoretical remaining power and the second theoretical remaining power is calculated as the capacity difference.

[0101] For another example, a first theoretical remaining capacity is obtained in the first static state of the battery, and then the battery state is continuously monitored. After the battery is in a charging state, a discharging state, a static state, and a discharging state in sequence, it is in a static state again to obtain a second theoretical remaining capacity in the second static state. The difference between the first theoretical remaining capacity and the second theoretical remaining capacity is calculated as the capacity difference.

[0102] S105: Obtain the current integrated capacity of the battery between two static states, and obtain the battery health based on the current integrated capacity and the capacity difference.

[0103] In a specific implementation scenario, the battery current of the battery is collected in real time, the time period between the first static state and the second static state is obtained, and the current is integrated according to the battery current in the time period, so as to obtain the current integrated power of the battery between the two static states. The battery health is obtained based on the current integrated power and the capacity difference. The integrated power is the value of the actual change in capacity. By comparing the capacity difference with the integrated power, the difference between the capacity difference and the actual change in capacity can be obtained, and the difference gives feedback on the battery health. The smaller the difference between the capacity difference and the integrated power, the higher the battery health.

[0104] In one implementation scenario, the battery health is calculated according to the following formula:

[0105]

[0106] Among them, SOH is the battery health, ΔCAP 2 is the capacity difference, ΔCAP 0 is the current integrated charge.

[0107] In other implementation scenarios, after obtaining the current integrated power, it is determined whether the current integrated power exceeds the preset power threshold, because if the power is too small, it may cause a large calculation error. For example, the preset power threshold is set to 3% of the total battery power. If the current integrated power does not exceed the preset power threshold, the second theoretical remaining power calculated this time is abandoned, and the battery is waited for to enter the static state again, and then steps S104-S105 are executed to obtain an accurate SOH.

[0108] It can be seen from the above description that in this embodiment, when the battery is in a static state, the previous state of the battery before the static state and the initial voltage at the current moment are obtained, the target voltage is obtained according to the previous state, the target moment when the battery reaches the target voltage is obtained, the estimated voltage is obtained according to the time difference between the current moment and the target moment and the initial voltage, the theoretical remaining capacity corresponding to the open circuit voltage is obtained, and the capacity difference between the two theoretical remaining capacities of the battery in the static state twice is obtained; the current integrated charge of the battery between the two static states is obtained, and the battery health is obtained based on the current integrated charge and the capacity difference. The battery health can be calculated without the battery being static for a preset time under strict conditions. It only needs to monitor the voltage change and integrated charge of the battery in the static state. No complicated operation or advanced equipment is required, which simplifies the estimation conditions of the battery health, does not need to use complicated algorithms, reduces the difficulty of estimation, and combines data such as current integrated charge and capacity difference to be more in line with the actual situation of the battery itself, thereby improving the estimation accuracy.

[0109] See also Figure 2 , Figure 21 is a flow chart of another embodiment of the method for calculating the health of a lithium battery provided by the present invention. The method for calculating the health of a lithium battery provided by the present invention comprises the following steps:

[0110] S201: Monitor the battery status. When it is detected that the battery is in a static state, obtain the previous state of the battery before the static state and the initial voltage at the current moment.

[0111] S202: Obtain a target voltage according to a previous state, obtain a target time when the battery reaches the target voltage, and obtain an estimated voltage according to a time difference between the current time and the target time and the initial voltage.

[0112] In a specific implementation scenario, steps S201-S202 are substantially consistent with steps S101-S102 in an embodiment of the lithium battery health calculation method provided by the present invention, and will not be described in detail here.

[0113] S203: Obtain the health calculation cycle, and determine whether the time difference exceeds the health calculation cycle. If so, execute step S204; if not, execute step S201.

[0114] In a specific implementation scenario, a health calculation cycle is preset, for example, 1s. When the battery first enters the static state, the battery voltage changes very quickly, and the time for the voltage to drop / rise by 1mV is very short, which may be less than 100ms. Monitoring such drastic data is likely to cause large errors, resulting in problems with the battery health calculated later. Therefore, setting a longer health calculation cycle allows data collection to be performed when the voltage drop has stabilized, ensuring the accuracy and reliability of the data.

[0115] Determine whether the time difference exceeds the health calculation cycle. If the time difference does not exceed the health calculation cycle, it means that the voltage is still in a stage of more drastic changes. The accuracy and credibility of the collected data are not high at this time. Therefore, it is necessary to abandon these data and re-perform the data collection operation, that is, re-execute step S201 to obtain a new initial voltage and current time, and obtain a new target voltage and target time based on the new initial voltage and current time. Obtain whether the time difference between the new target time and the new current time is greater than the health calculation cycle. If it is greater, execute step S204. If it is less than or equal to, repeat step S021 until the time difference between the new target time and the new current time is greater than the health calculation cycle.

[0116] S204: Continuously obtain a plurality of estimated voltages.

[0117] In a specific implementation scenario, several estimated voltages are obtained continuously. Steps S201 to S203 may be repeatedly executed to obtain multiple estimated voltages. Specifically, after obtaining the first estimated voltage U des1 Afterwards, the estimated voltage U des1 The target voltage and target time in the equation are used as the new current time and the new initial voltage, and steps S201-S203 are executed again to obtain the second estimated voltage U des2 The estimated voltage U des2 The target voltage and target time in the equation are used as the new current time and the new initial voltage, and steps S201-S203 are executed again to obtain the third estimated voltage U des3 .

[0118] In this embodiment, three estimated voltages are taken as an example for description. In other implementation scenarios, the number of estimated voltages may be any positive integer greater than 2 and is set according to user needs.

[0119] S205: Calculate the difference between every two adjacent estimated voltages in chronological order, and if the differences are all smaller than a preset threshold, take the average of the plurality of estimated voltages as the open circuit voltage.

[0120] In a specific implementation scenario, the difference between each two adjacent estimated voltages is calculated in chronological order, either from early to late or from late to early, without affecting the validity and reliability of subsequent results. In this implementation scenario, the example from early to late is used for illustration. des1 and U des2 The difference D 1 , and U des2 and U des3 The difference D 2 . Determine the difference D 1 and D 2 Are they all less than a preset threshold, for example, less than 10mV. If these differences are all less than the preset threshold, it means that the voltage change is already in a stable state, and the average of these estimated voltages is used as the open circuit voltage. In this implementation scenario, that is:

[0121]

[0122] S206: Obtain the theoretical remaining capacity corresponding to the open circuit voltage.

[0123] S207: Obtain the capacity difference between two theoretical remaining capacities of the battery in a static state twice.

[0124] S208: Obtain the current integrated capacity of the battery between two static states, and obtain the battery health based on the current integrated capacity and the capacity difference.

[0125] In a specific implementation scenario, steps S201-S208 are substantially consistent with steps S103-S105 in an embodiment of the lithium battery health calculation method provided by the present invention, and will not be described in detail here.

[0126] From the above description, it can be seen that in this embodiment, when the time difference exceeds the health calculation cycle, the time difference is valid, and the estimated voltage obtained is valid, which can ensure that the data is obtained in the stage of stable voltage change, avoiding the problem of large errors caused by collecting data when the voltage changes violently. Continuously obtain several estimated voltages; calculate the difference between every two adjacent estimated voltages. If the difference is less than the preset threshold, it means that the estimated voltage does not change much. At this time, the voltage change trend is stable, the obtained value is more accurate, and the error is small. The average of several estimated voltages is used as the open circuit voltage to ensure the accuracy of the obtained open circuit voltage.

[0127] Please refer to Figure 3 , Figure 3 FIG. 1 is a timing diagram of an embodiment of a method for calculating the health of a lithium battery provided by the present invention. 1 The battery is always monitored to be in a static state, and before that, the battery is in a charging state. Get t 1 The initial voltage at time U 1 The corresponding target voltage is U 1 -1, the target time to obtain the target voltage is t 2 The corresponding estimated voltage is

[0128] Continue to monitor the battery status. If the battery is still in a static state, 1 -1 as the new initial voltage, t 2 is the new current moment, so the new target voltage is U 1 -2, the target time for obtaining the new target voltage is t 3 , and the corresponding estimated voltage is

[0129] Continue to monitor the battery status. If the battery is still in a static state, 1 -2 as the new initial voltage, t 3 is the new current moment, so the new target voltage is U 1 -3, the target time for obtaining the new target voltage is t 4 , and the corresponding estimated voltage is

[0130] Get U des1 and U des2 The difference D 1 and Udes2 and U des3 The difference D 2 , difference D 1 and D 2 are both less than the preset threshold, the open circuit voltage

[0131] Continue to monitor the battery status, and when the battery is in a non-stationary state, record the battery status, such as the discharge state.

[0132] Continue to monitor the battery status, detect that the battery is currently in a static state again, and obtain the current time t 5 The initial voltage U 2 The corresponding target voltage is U 2 -1, the target time to obtain the target voltage is t 6 The corresponding estimated voltage is

[0133] Continue to monitor the battery status. If the battery is still in a static state, 2 +1 as the new initial voltage, t 6 is the new current moment, so the new target voltage is U 2 +2, the target time to obtain the new target voltage is t 7 , and the corresponding estimated voltage is

[0134] Continue to monitor the battery status. If the battery is still in a static state, 2 +2 as the new initial voltage, t 7 is the new current moment, so the new target voltage is U 2 +3, the target time to obtain the new target voltage is t 8 , and the corresponding estimated voltage is

[0135] Get U des4 and U des5 The difference D 3 and U des5 and U des6 The difference D 4 , difference D 3 and D 4 are both less than the preset threshold, the open circuit voltage

[0136] Get OCV 1 Corresponding SOC 1 , and OCV 2 Corresponding SOC 2 , get the full capacity of the battery full_cap, then the corresponding first theoretical remaining capacity is CAP1 =full_cap×SOC 1 , the second theoretical remaining capacity is CAP 2 =full_cap×SOC 2 Capacity difference ΔCAP 2 =CAP 2 -CAP 1 .

[0137] Get the battery current in real time and calculate the current at time t 1 At time t 5 Integrate the current between 1 At time t 5 The current integral capacity ΔCAP 0 The method for obtaining the current integral power can adopt the existing integration method, which will not be described here. Battery health

[0138] See also Figure 4 , Figure 4 The lithium battery health calculation device 10 includes an initial module 11 , an estimation module 12 , a capacity module 13 , a difference module 14 and an acquisition module 15 .

[0139] The initial module 11 is used to monitor the battery status. When it is detected that the battery is in a static state, the previous state of the battery before the static state and the initial voltage at the current moment are obtained; the estimation module 12 is used to obtain the target voltage according to the previous state, obtain the target moment when the battery reaches the target voltage, and obtain the estimated voltage according to the time difference between the current moment and the target moment and the initial voltage; the capacity module 13 is used to use the estimated voltage as the open circuit voltage when the estimated voltage meets the preset requirements, and obtain the theoretical remaining capacity corresponding to the open circuit voltage; the difference module 14 is used to obtain the capacity difference between two theoretical remaining capacities of the battery in the static state twice; the acquisition module 15 is used to obtain the current integrated capacity of the battery between the two static states, and obtain the battery health based on the current integrated capacity and the capacity difference.

[0140] The estimation module 12 is further configured to, when the previous state is a charging state, set the target voltage to be the initial voltage minus nmV; and when the previous state is a discharging state, set the target voltage to be the initial voltage plus n mV; wherein n is a value greater than 0.

[0141] The estimation module 12 is also used to obtain the estimated voltage according to the following formula when the previous state is the charging state:

[0142]

[0143] When the previous state is the discharge state, the estimated voltage is obtained according to the following formula:

[0144]

[0145] Among them, U des is the estimated voltage, Δt is the time difference, U 1 is the initial voltage, and M is the preset static time.

[0146] The estimation module 12 is also used to obtain the health calculation cycle and determine whether the time difference exceeds the health calculation cycle. If the time difference exceeds the health calculation cycle, the time difference is valid; if the time difference does not exceed the health calculation cycle, the time difference is invalid, and the step of obtaining the target time when the battery reaches the target voltage is re-executed.

[0147] The capacity module 13 is also used to continuously obtain a number of estimated voltages; calculate the difference between every two adjacent estimated voltages in chronological order, and if the differences are all smaller than a preset threshold, take the average of the several estimated voltages as the open circuit voltage.

[0148] The acquisition module 15 is also used to calculate the battery health according to the following formula:

[0149]

[0150] Among them, SOH is the battery health, ΔCAP 2 is the capacity difference, ΔCAP 0 is the current integrated charge.

[0151] It can be seen from the above description that in this embodiment, when the battery is in a static state, the previous state of the battery before the static state and the initial voltage at the current moment are obtained, the target voltage is obtained according to the previous state, the target moment when the battery reaches the target voltage is obtained, the estimated voltage is obtained according to the time difference between the current moment and the target moment and the initial voltage, the theoretical remaining capacity corresponding to the open circuit voltage is obtained, and the capacity difference between the two theoretical remaining capacities of the battery in the static state twice is obtained; the current integrated charge of the battery between the two static states is obtained, and the battery health is obtained based on the current integrated charge and the capacity difference. The battery health can be calculated without the battery being static for a preset time under strict conditions. It only needs to monitor the voltage change and integrated charge of the battery in the static state. No complicated operation or advanced equipment is required, which simplifies the estimation conditions of the battery health, does not need to use complicated algorithms, reduces the difficulty of estimation, and combines data such as current integrated charge and capacity difference to be more in line with the actual situation of the battery itself, thereby improving the estimation accuracy.

[0152] See also Figure 5 , Figure 51 is a circuit diagram of an embodiment of a control circuit of an energy storage device provided by the present invention. Figure 5 In the illustrated scenario, a target battery 21 is installed in the energy storage device 20. The target battery 21 may be a lithium battery or other types of batteries. The energy storage device 20 is provided with an input / output interface 22 for charging or discharging the energy storage device. The energy storage device 20 further includes a control chip 23 connected to the target battery 21 and the input / output interface 22 for obtaining information (including battery status, battery current, battery voltage, etc.) from the target battery 21 to perform Figure 1 or Figure 2 The energy storage device 20 further includes a display circuit 24 connected to the control chip 23 and configured to display the operation result of the control chip 23, for example, displaying the calculated SOH.

[0153] Please refer to Figure 6 and Figure 7 , Figure 6 It is a circuit diagram of an embodiment of a control chip provided by the present invention. Figure 7 This is a circuit diagram of an embodiment of the display circuit provided by the present invention. The control chip samples the battery current through the CSPL and CSNL pins, samples the battery voltage through the VBAT pin, uses the sampled information to calculate the battery health, and sends the health to the display circuit through the LED1_MCU and LED2_MCU pins. After the display circuit obtains the health, it controls the screen to display the lithium battery health through the SCL_LED and SDA_LED pins.

[0154] See also Figure 8 , Figure 8 3 is a schematic diagram of the structure of an embodiment of the energy storage device provided by the present invention. The energy storage device 30 includes a processor 31 and a memory 32. The processor 31 is coupled to the memory 32. The memory 32 stores a computer program, and the processor 31 executes the computer program when working to implement the above method. The detailed steps can be found above and will not be repeated here.

[0155] See also Fig. 9 , Fig. 9 4 is a schematic diagram of the structure of an embodiment of the computer-readable storage medium provided by the present invention. The computer-readable storage medium 40 stores at least one computer program 41, which is used to be executed by the processor to implement the above method. The detailed steps can be referred to above and will not be repeated here. In one embodiment, the computer-readable storage medium can be a storage chip, a hard disk, or a mobile hard disk or a USB flash drive, a CD, or other readable and writable storage tools in the terminal, or a server, etc.

[0156] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0157] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0158] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. For those skilled in the art, the technical solutions described in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents; and all these modifications and replacements should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for calculating the health of a lithium battery, characterized in that: include: Monitoring the battery state, and when it is detected that the battery is in a static state, obtaining the previous state of the battery before the static state and the initial voltage at the current moment; Acquire a target voltage according to the previous state, acquire a target time when the battery reaches the target voltage, and acquire an estimated voltage according to a time difference between the current time and the target time and the initial voltage; When the estimated voltage meets the preset requirement, taking the estimated voltage as the open circuit voltage, and obtaining the theoretical remaining capacity corresponding to the open circuit voltage; Obtaining a capacity difference between two theoretical remaining capacities of the battery in the static state twice; The current integrated capacity of the battery between the two static states is obtained, and the battery health is obtained based on the current integrated capacity and the capacity difference.

2. The lithium battery health calculation method according to claim 1, characterized in that: The step of acquiring the target voltage according to the previous state comprises: When the previous state is a charging state, the target voltage is the initial voltage minus nmV; When the previous state is a discharge state, the target voltage is the initial voltage plus nmV; Here, n is a value greater than 0.

3. The lithium battery health calculation method according to claim 2, characterized in that: The step of obtaining the estimated voltage according to the time difference between the current moment and the target moment and the initial voltage comprises: When the previous state is a charging state, the estimated voltage is obtained according to the following formula: When the previous state is a discharge state, the estimated voltage is obtained according to the following formula: Among them, U des is the estimated voltage, Δt is the time difference, U1 is the initial voltage, and M is the preset static time.

4. The lithium battery health calculation method according to claim 3, characterized in that: The step of obtaining the estimated voltage according to the time difference between the current moment and the target moment and the initial voltage comprises: Obtaining a health calculation cycle, and determining whether the time difference exceeds the health calculation cycle, if the time difference exceeds the health calculation cycle, the time difference is valid; If the time difference does not exceed the health calculation period, the time difference is invalid, and the step of obtaining the target time when the battery reaches the target voltage is performed again.

5. The lithium battery health calculation method according to claim 1, characterized in that: When the estimated voltage meets the preset requirement, the step of using the estimated voltage as the open circuit voltage comprises: Continuously acquiring a plurality of the estimated voltages; The difference between every two adjacent estimated voltages is calculated in time sequence, and if the differences are all smaller than a preset threshold, an average of several estimated voltages is used as the open circuit voltage.

6. The method for calculating the health of a lithium battery according to any one of claims 1 to 5, characterized in that: The step of obtaining the battery health based on the current integrated quantity and the capacity difference comprises: The battery health is calculated according to the following formula: Wherein, SOH is the battery health, ΔCAP2 is the capacity difference, and ΔCAP0 is the current integrated capacity.

7. A lithium battery health calculation device, characterized in that: include: An initial module is used to monitor the battery state, and when it is detected that the battery is in a static state, obtain the previous state of the battery before the static state and the initial voltage at the current moment; an estimation module, configured to obtain a target voltage according to the previous state, obtain a target time when the battery reaches the target voltage, and obtain an estimated voltage according to a time difference between the current time and the target time and the initial voltage; A capacity module, configured to use the estimated voltage as an open circuit voltage and obtain a theoretical remaining capacity corresponding to the open circuit voltage when the estimated voltage meets a preset requirement; A difference module, used for obtaining a capacity difference between two theoretical remaining capacities of the battery in the static state twice; The acquisition module is used to acquire the current integrated power of the battery between the two static states, and acquire the battery health based on the current integrated power and the capacity difference.

8. A control circuit for an energy storage device, characterized in that: include: An input / output interface, used to charge or discharge the energy storage device; A control chip, connected to the lithium battery pack and the input / output interface, for acquiring information from the lithium battery pack to execute the steps of the method according to any one of claims 1 to 6; The display circuit is connected to the control chip and is used for displaying according to the calculation result of the control chip.

9. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the processor is caused to execute the steps of the method according to any one of claims 1 to 6.

10. An energy storage device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method according to any one of claims 1 to 6.

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