Calibration Method, Device, Medium, Product, System and Equipment for State of Charge

Abstract

An embodiment of the present application provides a method, device, medium, product, system, and equipment for calibrating the state of charge; the method for calibrating the state of charge includes: obtaining a first measured terminal voltage of the battery and a first operating condition index corresponding to the first measured terminal voltage; determining a first model terminal voltage corresponding to the battery under the first operating condition index based on the equivalent circuit model of the battery and the current state of charge of the battery; determining a first voltage error of the first model terminal voltage based on the first measured terminal voltage; and calibrating the current state of charge of the battery based on the first voltage error and the reference voltage error range when the first operating condition index meets the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition. In this way, it is possible to more accurately identify whether the current state of charge of the battery needs to be calibrated, improve the accuracy of state of charge calibration, and reduce the problems of overvoltage or undervoltage of the battery caused by state of charge deviation.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to a method, device, medium, product, system and equipment for calibrating the state of charge. Background Art

[0002] This section aims to provide background or context for the embodiments of the present application. The description herein is not admitted to be prior art merely because it is included in this section.

[0003] In the related art, if the state of charge (SOC) deviation accumulated during the long-term use of a battery is not corrected, it will cause undesirable phenomena such as overvoltage or undervoltage of the battery, thereby affecting the performance of the electrical equipment supported by the battery.

[0004] Therefore, with the wide application of batteries, how to correct the state of charge of the battery is an urgent problem to be solved at present. Summary of the Invention

[0005] In view of this, embodiments of the present application are expected to provide a method, device, medium, product, system and equipment for calibrating the state of charge, which can correct the SOC deviation accumulated during the use of the battery, reduce problems such as battery overvoltage or battery undervoltage caused by the SOC deviation, and thus improve the performance of the battery product.

[0006] Embodiments of the present application provide a method for calibrating the state of charge, which includes:

[0007] Obtain the first measured terminal voltage of the battery and the first operating condition index corresponding to the first measured terminal voltage;

[0008] Based on the equivalent circuit model of the battery and the current state of charge of the battery, determine the first model terminal voltage corresponding to the battery under the first operating condition index;

[0009] Based on the first measured terminal voltage, determine the first voltage error of the first model terminal voltage;

[0010] When the first operating condition index meets the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition, calibrate the current state of charge of the battery based on the first voltage error and the reference voltage error range; the reference voltage error range represents the error range of the model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets the target credible condition.

[0011] In the embodiments of the present application, the first measured terminal voltage of the battery and the corresponding first operating condition index are obtained; based on the equivalent circuit model of the battery and the current state of charge, the first model terminal voltage corresponding to the first measured terminal voltage under the first operating condition index is determined, and further the first voltage error is determined; when the first operating condition index meets the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition, the current state of charge of the battery is calibrated based on the first voltage error and the reference voltage error range. In this way, on the one hand, since there is a specific correspondence between the open circuit voltage (OCV) of the battery and the SOC, by introducing the equivalent circuit model of the battery, the voltage error between the battery terminal voltage calculated by the model and the actually measured battery terminal voltage can be used to reflect the deviation of the SOC; on the other hand, under the target operating condition, if the SOC of the battery meets the target credibility condition, the error range of the model terminal voltage determined based on the equivalent circuit model will be within the reference voltage error range. In this way, by comparing the first operating condition index with the target operating condition and comparing the first voltage error under the first operating condition index with the reference voltage error range under the target operating condition, it is possible to more accurately determine whether the current state of charge of the battery is credible, and thus more accurately identify whether the current state of charge of the battery needs to be calibrated. Thus, when the first operating condition index meets the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition, by calibrating the current state of charge of the battery based on the first voltage error and the reference voltage error range, the opportunity for SOC correction can be increased, the correction effect of the SOC can be improved, the accuracy of the state of charge calibration can be improved, thereby reducing the problem of overvoltage or undervoltage of the battery caused by the SOC deviation, and further improving the device performance of the electrical device supported by the battery.

[0012] In some embodiments, calibrating the current state of charge of the battery based on the first voltage error and the reference voltage error range includes:

[0013] Based on the first voltage error and the reference voltage error range, a target voltage error range is determined; the upper limit of the target voltage error range is determined based on the difference between the first voltage error and the lower limit of the reference voltage error range, and the lower limit of the target voltage error range is determined based on the difference between the first voltage error and the upper limit of the reference voltage error range;

[0014] Based on the target voltage error range and the current state of charge of the battery, a target state of charge range of the battery is determined;

[0015] Based on the target state of charge range, the current state of charge of the battery is calibrated.

[0016] In the above embodiments, based on the first voltage error and the reference voltage error range, a target voltage error range is determined; and based on the target voltage error range and the current state of charge of the battery, a target state of charge range of the battery is determined; and further based on the target state of charge range, the current state of charge of the battery is calibrated. In this way, since the reference voltage error range represents the error range of the model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets the target credibility condition, and the upper limit of the target voltage error range is determined based on the difference between the first voltage error and the lower limit of the reference voltage error range, and the lower limit of the target voltage error range is determined based on the difference between the first voltage error and the upper limit of the reference voltage error range, therefore, the target voltage error range can represent the error range of the open-circuit voltage caused by the SOC deviation of the battery. Thus, the target state of charge range determined based on the target voltage error range and the current state of charge of the battery can better reflect the true SOC of the battery, and further based on this target state of charge range, the accuracy of calibrating the current state of charge of the battery can be improved.

[0017] In some embodiments, determining the target state of charge range of the battery based on the target voltage error range and the current state of charge of the battery includes:

[0018] Based on the current state of charge of the battery, query the first correspondence relationship to obtain an estimated value of the current open-circuit voltage of the battery; the first correspondence relationship represents the correspondence relationship between the open-circuit voltage and the state of charge of the battery;

[0019] Based on the estimated value and the target voltage error range, determine the target open-circuit voltage range of the battery;

[0020] Based on the target open-circuit voltage range and the first correspondence relationship, determine the target state of charge range of the battery.

[0021] In the above embodiments, based on the current state of charge of the battery, query the first correspondence relationship to obtain an estimated value of the current open-circuit voltage of the battery; and based on the estimated value and the target voltage error range, determine the target open-circuit voltage range of the battery; and further based on the target open-circuit voltage range and the first correspondence relationship, determine the target state of charge range of the battery. In this way, based on the correspondence relationship between the open-circuit voltage and the state of charge of the battery, the target state of charge range of the battery can be quickly and accurately determined based on the target voltage error range and the current state of charge of the battery, thereby improving the accuracy and efficiency of battery SOC calibration.

[0022] In some embodiments, calibrating the current state of charge of the battery based on the target state of charge range includes:

[0023] When the state of charge of the battery is greater than the first threshold, calibrate the state of charge of the battery to the first threshold; the first threshold includes the upper limit of the target state of charge range.

[0024] When the state of charge of the battery is less than the second threshold, calibrate the state of charge of the battery to the second threshold; the second threshold includes the lower limit of the target state of charge range.

[0025] In the above embodiments, based on the maximum threshold and the minimum threshold of the state of charge corresponding to the target state of charge range, calibrate the current state of charge of the battery. In this way, by limiting the state of charge of the calibrated battery within the target state of charge range, the accuracy of the battery SOC calibration can be further improved.

[0026] In some embodiments, calibrating the current state of charge of the battery based on the target state of charge range includes:

[0027] When the rate of change of the open-circuit voltage of the battery with respect to the state of charge within the target state of charge range exceeds the rate-of-change threshold, calibrate the current state of charge of the battery.

[0028] In the above embodiments, when the rate of change of the open-circuit voltage of the battery with respect to the state of charge within the target state of charge range exceeds the rate-of-change threshold, calibrate the current state of charge of the battery. In this way, considering that when the rate of change of the open-circuit voltage with respect to the state of charge does not exceed the rate-of-change threshold, the rate of change of the open-circuit voltage with respect to the state of charge is usually small (for example, the OCV corresponding to the state of charge of the battery is in the plateau region). In this case, there will be a large error in inversely deriving the upper and lower limits of the SOC based on the upper and lower limits of the OCV and the corresponding relationship between the SOC and the OCV, and it is easy to have problems with inaccurate calibration. Therefore, calibrating the SOC when the rate of change of the open-circuit voltage of the battery with respect to the state of charge within the target state of charge range exceeds the rate-of-change threshold can reduce the inaccurate calibration caused by the OCV being in the plateau region and improve the accuracy and referenceability of the calibration result.

[0029] In some embodiments, obtaining the first measured terminal voltage of the battery and the first operating condition index corresponding to the first measured terminal voltage includes:

[0030] Collect the first measured terminal voltages corresponding to multiple moments within the target state of charge change interval of the battery and the first operating condition indexes corresponding to the respective first measured terminal voltages;

[0031] Determining the first voltage error of the first model terminal voltage based on the first measured terminal voltage includes:

[0032] Take the average of the first measured terminal voltages collected at multiple moments within the target state of charge change interval to obtain the average measured terminal voltage;

[0033] Calculate the average value of multiple first model terminal voltages corresponding to multiple first measurement terminal voltages to obtain an average model terminal voltage;

[0034] Determine the difference between the average model terminal voltage and the average measurement terminal voltage as the first voltage error.

[0035] In the above embodiments, within the target state of charge change interval, collect the first measurement terminal voltages corresponding to different moments and the first operating condition indicators corresponding to each first measurement terminal voltage multiple times; and calculate the average of the multiple first measurement terminal voltages collected within the target state of charge change interval and the first model terminal voltages corresponding to the multiple first measurement terminal voltages respectively; determine the difference between the obtained average model terminal voltage and the average measurement terminal voltage as the first voltage error. In this way, based on the average values of the first measurement terminal voltage and the first model terminal voltage within the state of charge change interval, the influence of abnormal data on determining the first voltage error can be reduced, and the accuracy and referenceability of the first voltage error can be improved.

[0036] In some embodiments, the first operating condition indicator includes temperature and / or current rate, and the calibration method further includes at least one of the following:

[0037] When the first operating condition indicator includes temperature and the minimum temperature within the target state of charge change interval is not less than the minimum temperature threshold, determine that the first operating condition indicator meets the target operating condition;

[0038] When the first operating condition indicator includes current rate and the average current rate within the target state of charge change interval is not greater than the average current rate threshold, determine that the first operating condition indicator meets the target operating condition.

[0039] In this way, considering that there may be a situation where the battery temperature abnormally decreases within the target state of charge change interval, determining that the minimum temperature among the temperatures corresponding to multiple moments within the target state of charge change interval is not less than the minimum temperature threshold can reduce the influence of abnormal low-temperature data on determining whether the first operating condition indicator meets the target operating condition, and improve the accuracy and stability of determining that the first operating condition indicator meets the target operating condition. Considering that the current rate may fluctuate at different moments within the target state of charge change interval, determining that the average current rate within the target state of charge change interval is not greater than the average current rate threshold can reduce the influence of the fluctuation of the current rate at different moments on determining whether the first operating condition indicator meets the target operating condition, and improve the accuracy and stability of determining that the first operating condition indicator meets the target operating condition. At the same time, by combining two different operating condition indicators, the accuracy and stability of determining that the first operating condition indicator meets the target operating condition can be further improved.

[0040] In some embodiments, the calibration method further includes:

[0041] Determine at least one candidate operating condition and the corresponding candidate voltage error range for each candidate operating condition; the candidate voltage error range characterizes the error range of the model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets the target confidence condition.

[0042] Determine the target operating condition corresponding to the reference voltage error range from at least one candidate operating condition.

[0043] In the above embodiments, by determining at least one candidate operating condition and the corresponding candidate voltage error range for each candidate operating condition, the target operating condition corresponding to the reference voltage error range can be quickly and accurately determined from at least one candidate operating condition.

[0044] In some embodiments, determining at least one candidate operating condition and the corresponding candidate voltage error range for the candidate operating condition includes:

[0045] Obtain at least one second measured terminal voltage of the battery during the target test process, and the corresponding second operating condition index and measured state of charge for each second measured terminal voltage.

[0046] For each second measured terminal voltage, based on the equivalent circuit model and the corresponding measured state of charge, determine the second model terminal voltage of the battery under the corresponding second operating condition index, and determine the second voltage error of the second model terminal voltage based on the second measured terminal voltage.

[0047] Based on the second operating condition index and the corresponding second voltage error corresponding to each second measured terminal voltage, determine at least one candidate operating condition and the corresponding candidate voltage error range with a corresponding relationship.

[0048] In the above embodiments, by using at least one second measured terminal voltage collected during the target test process, and the corresponding second operating condition index and measured state of charge for each second measured terminal voltage; determine the second model terminal voltage of the battery under the corresponding second operating condition index, and determine the second voltage error of the second model terminal voltage based on the second measured terminal voltage; further based on the second operating condition index and the corresponding second voltage error corresponding to each second measured terminal voltage, determine at least one candidate operating condition and the corresponding candidate voltage error range with a corresponding relationship. In this way, based on the corresponding relationship between at least one second voltage error and the second operating condition index, the accuracy of finding the candidate operating condition and the corresponding candidate voltage error range can be improved, and further the accuracy of determining the target operating condition from the candidate operating conditions based on the reference voltage error range can be improved.

[0049] An embodiment of the present application provides a state of charge calibration device, and the calibration device includes:

[0050] An acquisition module, configured to acquire a first measured terminal voltage of a battery and a first operating condition index corresponding to the first measured terminal voltage;

[0051] A first determination module, configured to determine a first model terminal voltage corresponding to the battery under the first operating condition index based on an equivalent circuit model of the battery and a current state of charge of the battery;

[0052] A second determination module, configured to determine a first voltage error of the first model terminal voltage based on the first measured terminal voltage;

[0053] A calibration module, configured to calibrate the current state of charge of the battery based on the first voltage error and a reference voltage error range when the first operating condition index meets a target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition; the reference voltage error range represents an error range of a model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets a target credibility condition.

[0054] An embodiment of the present application provides a computer-readable storage medium storing a computer program that can be executed by a processor to implement the above method for calibrating the state of charge.

[0055] An embodiment of the present application provides a computer program product, including a computer program or instruction, which when executed by a processor, implements some or all of the steps in the above method for calibrating the state of charge.

[0056] An embodiment of the present application provides a battery system, including at least one battery and a battery management system; the battery management system is configured to implement some or all of the steps in the above method for calibrating the state of charge.

[0057] An embodiment of the present application provides an electrical device, including the above battery system. Description of the Drawings

[0058] Figure 1A It is a first schematic diagram of the implementation process of a method for calibrating the state of charge provided by an embodiment of the present application;

[0059] Figure 1B It is a schematic diagram of the composition structure of an equivalent circuit model provided by an embodiment of the present application;

[0060] Figure 2 It is a schematic diagram of the implementation process of a method for calibrating the state of charge provided by an embodiment of the present application Figure 2 ;

[0061] Figure 3 It is a schematic diagram of the composition structure of a device for calibrating the state of charge provided by an embodiment of the present application;

[0062] Figure 4 It is a schematic diagram of the composition structure of a battery system provided by an embodiment of the present application;

[0063] Figure 5 It is a schematic diagram of the composition structure of an electrical device provided by an embodiment of the present application. Detailed implementation manners

[0064] It should be noted that, without conflict, the embodiments in the present application and the technical features in the embodiments may be combined with each other. The detailed description in the specific implementation manners should be understood as an explanatory illustration of the purpose of the present application and should not be regarded as an improper limitation to the present application.

[0065] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusion.

[0066] In the description of the embodiments of the present application, the technical terms "first", "second", "third", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, "a plurality of" means two or more unless otherwise specifically defined.

[0067] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0068] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there may be three relationships, for example, A and / or B, which may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0069] Batteries are widely used as the power source and energy source of electrical devices. However, as the usage process increases, the SOC deviation will gradually accumulate. If the accumulated SOC deviation is not corrected, it will cause undesirable phenomena such as overvoltage or undervoltage of the battery, thereby affecting the performance of the electrical device supported by the battery.

[0070] An embodiment of the present application provides a method for calibrating the state of charge, as Figure 1A shown, the calibration method may include the following steps S101 to S104:

[0071] Step S101, obtain the first measured terminal voltage of the battery and the first operating condition index corresponding to the first measured terminal voltage.

[0072] Here, the types of batteries may include, but are not limited to, at least one of lithium-ion batteries, zinc-manganese batteries, lead-acid batteries, etc.

[0073] The first measured terminal voltage may be the actual terminal voltage measured for the battery.

[0074] The first operating condition index may be used to characterize the working environment and / or working state of the battery at the first measured terminal voltage, and may be the operating condition index collected when measuring the first measured terminal voltage; wherein, the operating condition index may include, but is not limited to, at least one of current, current rate, temperature, humidity, etc.

[0075] In some embodiments, the first measured terminal voltage of the battery and the first operating condition index corresponding to the first measured terminal voltage may be obtained during the use of the battery; or the first measured terminal voltage of the battery and the first operating condition index corresponding to the first measured terminal voltage may be obtained when the battery is in a non-use state (for example, a stationary state).

[0076] In some embodiments, the first measured terminal voltage of the battery and the first operating condition index corresponding to the first measured terminal voltage may be obtained in real time; or the first measured terminal voltage of the battery and the first operating condition index corresponding to the first measured terminal voltage may be obtained at regular intervals based on a target time interval.

[0077] Step S102, based on the equivalent circuit model of the battery and the current state of charge of the battery, determine the first model terminal voltage corresponding to the battery under the first operating condition index.

[0078] Here, the equivalent circuit model of the battery may be used as an open-loop model of the battery to simulate the dynamic characteristics of the battery and reflect the voltage change characteristics of the battery during charge and discharge, such as effects of ohmic voltage drop, electrochemical polarization, and concentration polarization. In implementation, the equivalent circuit model of the battery may be any suitable open-loop model, and the embodiments of the present application do not limit this.

[0079] In some embodiments, the equivalent circuit model of the battery may include, but is not limited to, at least one of a first-order resistance-capacitance (RC) equivalent circuit model, a second-order RC equivalent circuit model, etc.

[0080] The first model terminal voltage can be the battery terminal voltage estimated based on the model parameters of the equivalent circuit model and the current state of charge of the battery under the first operating condition index; wherein, the model parameters can include at least one of, but are not limited to, the open-circuit voltage of the battery, the equivalent internal resistance of the battery, the polarization resistance, the voltage of the polarization resistance, etc.

[0081] In some embodiments, based on the current state of charge of the battery, the first correspondence between the open-circuit voltage of the battery and the state of charge can be queried to obtain the open-circuit voltage corresponding to the current state of charge; after establishing the equivalent circuit model of the battery, the first operating condition index and the open-circuit voltage corresponding to the current state of charge are input into the equivalent circuit model to obtain the first model terminal voltage.

[0082] Exemplarily, as Figure 1B shown, taking the second-order RC equivalent circuit model 10 as an example, the equivalent circuit model 10 includes a battery equivalent internal resistance 11, polarization resistances 12 and 13, a polarization capacitor 14 corresponding to the polarization resistance 12, a polarization capacitor 15 corresponding to the polarization resistance 13, an equivalent voltage source 16, a battery positive electrode 17, and a battery negative electrode 18.

[0083] According to Kirchhoff's law, the input-output relationship of the equivalent circuit model 10 can be seen in formulas (1) to (3):

[0084] (1);

[0085] (2);

[0086] (3);

[0087] Wherein, U t is the first model terminal voltage corresponding to the equivalent circuit model 10 between the battery positive electrode 17 and the battery negative electrode 18, U OC is the open-circuit voltage of the equivalent voltage source 16, that is, the open-circuit voltage of the battery, R 0 is the internal resistance value of the battery equivalent internal resistance 11, U D1 and U D2 are the voltage values of the polarization resistances 12 and 13 respectively, R D1 and R D2 are the resistance values of the polarization resistances 12 and 13 respectively, C D1 and C D2 are the capacitance values of the polarization capacitors 14 and 15 respectively, i Lis the current value. U OC The state of charge may be determined based on the current state of charge of the battery and the corresponding relationship between the state of charge of the battery and the open circuit voltage.

[0088] It can be understood that based on formula (1), when there is no deviation in SOC, U OC Without error, the voltage at the first model terminal of the equivalent circuit model 10 is U t The error comes from U D1 The error, U D2 errors, and / or i L R 0 error, where U D1 The error, U D2 The error, and i L R The error of 0 is usually related to operating conditions such as current ratio and / or temperature.

[0089] In some implementations, the model parameters of the equivalent circuit model may be identified offline by using a target optimization algorithm through test experiments.

[0090] For example, the least square method can be used to analyze the Figure 1B The model parameter U of the equivalent circuit model 10 in OC , R0, R D1 , U D1 , R D2 and U D2 The fitting is performed to complete the off-line identification process of the model parameters of the equivalent circuit model 10 .

[0091] The current state of charge of the battery can be estimated based on the target parameters of the battery at the current moment; wherein the target parameters may include but are not limited to at least one of the open circuit voltage of the battery, the current of the battery, the discharge capacity of the battery, the rated capacity of the battery, etc.

[0092] For example, the open circuit voltage of the battery at the current moment can be obtained by measuring, and the current state of charge of the battery can be estimated by the open circuit voltage method.

[0093] For example, the current of the battery at the current moment and at historical moments can be measured, and the current state of charge of the battery can be estimated by the ampere-hour integration method.

[0094] In some embodiments, the current state of charge of the battery can be estimated by a battery management component. For example, the current state of charge of the battery can be estimated by a Battery Management System (BMS).

[0095] Step S103: Determine a first voltage error of the first model terminal voltage based on the first measured terminal voltage.

[0096] Here, the first voltage error can characterize the error between the battery terminal voltage calculated by the equivalent circuit model and the actually measured battery terminal voltage under the first operating condition index.

[0097] In some embodiments, the first voltage error can be determined based on the difference between the first model terminal voltage and the first measured terminal voltage.

[0098] For example, the first voltage error can be the difference between the first model terminal voltage and the first measured terminal voltage.

[0099] As another example, the first voltage error can be the average value of the differences between the first model terminal voltages at multiple moments within a target time period and the corresponding first measured terminal voltages.

[0100] As still another example, the first voltage error can be the difference between the average model terminal voltage obtained by averaging the first model terminal voltages at multiple moments within a target time period and the average measured terminal voltage obtained by averaging the corresponding first measured terminal voltages at multiple moments.

[0101] Exemplarily, the process of determining the first voltage error Q can refer to formula (4):

[0102] (4);

[0103] where V t1 is the first model terminal voltage, and V t2 is the first measured terminal voltage.

[0104] Step S104: When the first operating condition index meets the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition, calibrate the current state of charge of the battery based on the first voltage error; the reference voltage error range characterizes the error range of the model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets the target credibility condition.

[0105] Here, the target credibility condition can characterize that the state of charge of the battery is credible, and the model terminal voltage corresponding to the equivalent circuit model determined based on this state of charge is credible, that is, under the target operating condition corresponding to the reference voltage error range, the error range of the model terminal voltage of the battery is within the reference voltage error range.

[0106] In some embodiments, it may be determined that the current state of charge meets the target credibility condition when the absolute value of the difference between the current state of charge of the battery and the corresponding true state of charge is less than an absolute value threshold.

[0107] For example, when the current state of charge of the battery is 28% and the true state of charge is 25%, the absolute value of the difference between the current state of charge and the corresponding true state of charge is 3%, which is less than the absolute value threshold of 5%, then the current state of charge meets the target credibility condition.

[0108] The target operating condition may include preset conditions corresponding to one or more operating condition indicators. For example, it may include at least one of the following: the temperature meets the target temperature condition, the current meets the target current condition, the humidity meets the target humidity condition, etc.

[0109] In some embodiments, when the target operating conditions are different, the corresponding reference voltage error ranges may be different.

[0110] It can be understood that when the first operating condition indicator meets the target operating condition, the error range of the model terminal voltage of the battery should be within the reference voltage error range. If the first voltage error is not within the reference voltage error range corresponding to the target operating condition, it can be shown that there is a deviation in the SOC of the battery, resulting in a deviation between the OCV determined based on the SOC and the actual OCV, further resulting in an inaccurate determined model terminal voltage, so that the error range of the model terminal voltage determined based on the equivalent circuit model is not within the reference voltage error range. In this case, calibrating the SOC of the battery at the current moment can improve the accuracy of the battery SOC.

[0111] Exemplarily, the reference voltage error range may include, but is not limited to, [-30mV, 30mV], [-25mV, 25mV], [-20mV, 20mV], etc.

[0112] In some embodiments, the calibration of the current state of charge of the battery based on the first voltage error in step S104 above may include the following step S1041:

[0113] Step S1041: Calibrate the current state of charge of the battery based on the first voltage error and the reference voltage error range.

[0114] Here, since the reference voltage error range can characterize the error range of the model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery under the target operating condition satisfies the target credibility condition, and the first operating condition index corresponding to the first voltage error satisfies the target operating condition, therefore, by comprehensively analyzing the first voltage error and the reference voltage error range, the voltage error range caused by the SOC deviation of the battery can be obtained, thereby reflecting the SOC deviation of the battery. Thus, based on the first voltage error and the reference voltage error range, the current state of charge of the battery can be calibrated.

[0115] In some embodiments, based on the first voltage error and the reference voltage error range, the current state of charge of the battery can be calibrated at least once so that the new first voltage error determined based on the calibrated SOC is within the reference voltage error range.

[0116] In the embodiments of the present application, the first measured terminal voltage of the battery and the corresponding first operating condition index are obtained; based on the equivalent circuit model of the battery and the current state of charge, the first model terminal voltage corresponding to the first measured terminal voltage under the first operating condition index is determined, and further the first voltage error is determined; when the first operating condition index satisfies the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition, the current state of charge of the battery is calibrated based on the first voltage error and the reference voltage error range. In this way, on the one hand, since there is a specific correspondence between the open circuit voltage (OCV) of the battery and the SOC, by introducing the equivalent circuit model of the battery, the voltage error between the battery terminal voltage calculated by the model and the actually measured battery terminal voltage can be used to reflect the deviation of the SOC; on the other hand, since under the target operating condition, if the SOC of the battery satisfies the target credibility condition, the error range of the model terminal voltage determined based on the equivalent circuit model will be within the reference voltage error range. In this way, by comparing the first operating condition index with the target operating condition and comparing the first voltage error under the first operating condition index with the reference voltage error range under the target operating condition, it can be more accurately determined whether the current state of charge of the battery is credible, and thus more accurately identify whether the current state of charge of the battery needs to be calibrated. Thus, when the first operating condition index satisfies the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition, by calibrating the current state of charge of the battery based on the first voltage error and the reference voltage error range, the correction opportunity of the SOC can be increased, the correction effect of the SOC can be improved, the accuracy of the state of charge calibration can be improved, thereby reducing the problem of overvoltage or undervoltage of the battery caused by the SOC deviation, and further improving the device performance of the electrical device supported by the battery.

[0117] In some embodiments, the calibration of the current state of charge of the battery based on the first voltage error and the reference voltage error range in step S104 may include the following steps S201 to S203:

[0118] Step S201: Based on the first voltage error and the reference voltage error range, determine the target voltage error range; the upper limit of the target voltage error range is determined based on the difference between the first voltage error and the lower limit of the reference voltage error range, and the lower limit of the target voltage error range is determined based on the difference between the first voltage error and the upper limit of the reference voltage error range.

[0119] Here, in the case of a deviation in the SOC, the first voltage error can be jointly determined by the voltage error of the model terminal voltage when the state of charge of the battery satisfies the target credibility condition and the voltage error of the open-circuit voltage caused by the SOC deviation (i.e., not satisfying the target credibility condition); among them, the voltage error of the model terminal voltage when the state of charge of the battery satisfies the target credibility condition can be determined according to the voltage error of the polarization resistance and / or the voltage error of the equivalent internal resistance of the battery.

[0120] The target voltage error range can characterize the range of the voltage error of the open-circuit voltage caused by the SOC deviation.

[0121] Exemplarily, the relationship between the first voltage error Q, the voltage error Q1 of the model terminal voltage when the state of charge of the battery satisfies the target credibility condition, and the voltage error Q2 caused by the SOC deviation can be seen in formula (5):

[0122] (5);

[0123] Among them, the value range of Q1 is the reference voltage error range, that is, the voltage error of the model terminal voltage when the state of charge of the battery satisfies the target credibility condition is not less than the lower limit of the reference voltage error range and not greater than the upper limit of the reference voltage error range;

[0124] Therefore, when the first voltage error Q is determined and the reference voltage error range (i.e., the value range of Q1) is determined, the target voltage error range (i.e., the value range of Q2) can also be determined.

[0125] Step S202: Based on the target voltage error range and the current state of charge of the battery, determine the target state of charge range of the battery.

[0126] Here, the target state of charge range can characterize the range of the true SOC under the first working condition index.

[0127] The target voltage error range can characterize the range of the difference between the OCV corresponding to the currently estimated SOC (i.e., the state of charge at present) and the OCV corresponding to the true SOC.

[0128] Exemplarily, formula (5) can also be expressed as formula (6):

[0129] (6);

[0130] Where, V OCV1 is the OCV corresponding to the currently estimated SOC, and V OCV2 is the OCV corresponding to the true SOC.

[0131] Since the target voltage error range can characterize the range of the error between the OCV corresponding to the state of charge at present and the OCV corresponding to the true SOC, based on the target voltage error range and the OCV corresponding to the state of charge at present, the OCV range corresponding to the true SOC can be determined. Further, by using the corresponding relationship between the OCV and SOC of the battery, the target state of charge range of the battery can be determined.

[0132] Exemplarily, when the target voltage error range (i.e., the value range of Q2) is determined, the value range of V OCV1 -V OCV2 can also be determined. Further, the upper limit of V OCV2 is the difference between V OCV1 and the lower limit of Q2, and the lower limit of V OCV2 is the difference between V OCV1 and the upper limit of Q2. Further, by using the corresponding relationship between the OCV and SOC of the battery, the upper limit of the true SOC corresponding to the upper limit of V OCV2 and the lower limit of the true SOC corresponding to the lower limit of V OCV2 (i.e., the target state of charge range) can be determined.

[0133] Step S203: Calibrate the current state of charge of the battery based on the target state of charge range.

[0134] Here, the current state of charge of the battery can be calibrated when the current state of charge of the battery exceeds the target state of charge range.

[0135] Exemplarily, when the current state of charge of the battery is within the target state of charge range, the current state of charge of the battery may not be corrected.

[0136] In the embodiments of the present application, based on the first voltage error and the reference voltage error range, a target voltage error range is determined; and based on the target voltage error range and the current state of charge of the battery, a target state of charge range of the battery is determined; further, based on the target state of charge range, the current state of charge of the battery is calibrated. In this way, since the reference voltage error range represents the error range of the model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets the target credibility condition, and the upper limit of the target voltage error range is determined based on the difference between the first voltage error and the lower limit of the reference voltage error range, and the lower limit of the target voltage error range is determined based on the difference between the first voltage error and the upper limit of the reference voltage error range, therefore, the target voltage error range can represent the error range of the open-circuit voltage caused by the SOC deviation of the battery. Thus, the target state of charge range determined based on the target voltage error range and the current state of charge of the battery can better reflect the true SOC of the battery, and further, based on this target state of charge range, the accuracy of calibrating the current state of charge of the battery can be improved.

[0137] In some embodiments, the above step S202 may include the following steps S301 to S303:

[0138] Step S301: Based on the current state of charge of the battery, query the first correspondence relationship to obtain an estimated value of the current open-circuit voltage of the battery; the first correspondence relationship represents the correspondence relationship between the open-circuit voltage and the state of charge of the battery.

[0139] Here, querying the first correspondence relationship may include, but is not limited to, querying at least one of a table, a set, a function, a curve, etc. that can represent the correspondence relationship between the open-circuit voltage and the state of charge of the battery.

[0140] The estimated value of the current open-circuit voltage of the battery may correspond to the OCV corresponding to the currently estimated SOC in the above state of charge calibration method.

[0141] Step S302: Based on the estimated value and the target voltage error range, determine the target open-circuit voltage range of the battery.

[0142] Here, the target open-circuit voltage range may correspond to the range of the OCV corresponding to the true SOC in the above state of charge calibration method.

[0143] Exemplarily, based on formula (4) and formula (6), formula (7) can be obtained:

[0144] (7);

[0145] It can be understood that when the estimated value is determined, that is, the OCV corresponding to the currently estimated SOC is determined, the target voltage error range is determined, the first model terminal voltage and the first measured terminal voltage are determined, and the state of charge of the battery meets the target credibility condition, and the voltage error of the model terminal voltage is within the reference voltage error range, the OCV range corresponding to the true SOC, that is, the target open-circuit voltage range, can be determined according to formula (7).

[0146] Step S303: Based on the target open-circuit voltage range and the first correspondence, determine the target state of charge range of the battery.

[0147] Here, based on the first correspondence, the state of charge corresponding to the open-circuit voltage within the target open-circuit voltage range can be determined, and further based on the state of charge corresponding to the open-circuit voltage within the target open-circuit voltage range, the target state of charge range can be determined.

[0148] In the embodiments of the present application, based on the current state of charge of the battery, the first correspondence is queried to obtain the estimated value of the current open-circuit voltage of the battery; and based on the estimated value and the target voltage error range, the target open-circuit voltage range of the battery is determined; further based on the target open-circuit voltage range and the first correspondence, the target state of charge range of the battery is determined. In this way, based on the correspondence between the open-circuit voltage and the state of charge of the battery, the target state of charge range of the battery can be quickly and accurately determined based on the target voltage error range and the current state of charge of the battery, thereby improving the accuracy and efficiency of battery SOC calibration.

[0149] In some embodiments, the above step S203 may include the following steps S401 to S402:

[0150] Step S401: When the current state of charge of the battery is greater than the first threshold, calibrate the state of charge of the battery to the first threshold; the first threshold includes the upper limit of the target state of charge range.

[0151] Here, the current state of charge of the battery being greater than the first threshold may indicate that the current state of charge of the battery is falsely high compared to the state of charge credible range. Therefore, it is necessary to calibrate the state of charge of the battery to the credible range, that is, calibrate it to the upper limit of the credible range.

[0152] Exemplarily, based on the above formula (7) and the target voltage error range, formula (8) can be obtained:

[0153] (8);

[0154] where Q 1max is the upper limit of Q1, V OCV2maxis the upper limit of the OCV corresponding to the true SOC. After determining the upper limit of the OCV corresponding to the true SOC, based on the corresponding relationship between SOC and OCV, the upper limit of the target state of charge range, i.e., the first threshold, can be determined.

[0155] Step S402: When the current state of charge of the battery is less than the second threshold, calibrate the state of charge of the battery to the second threshold; the second threshold includes the lower limit of the target state of charge range.

[0156] Here, the current state of charge of the battery being less than the second threshold can indicate that the current state of charge of the battery is falsely low compared to the credible range of the state of charge. Therefore, it is necessary to calibrate the state of charge of the battery to the credible range, that is, calibrate it to the lower limit of the credible range.

[0157] Exemplarily, based on the above formula (7) and the target voltage error range, formula (9) can be obtained:

[0158] (9);

[0159] where Q 1min is the lower limit of Q1, V OCV2min is the lower limit of the OCV corresponding to the true SOC. After determining the lower limit of the OCV corresponding to the true SOC, based on the corresponding relationship between SOC and OCV, the lower limit of the target state of charge range, i.e., the second threshold, can be determined.

[0160] In the embodiments of the present application, the current state of charge of the battery is calibrated based on the maximum threshold and the minimum threshold of the state of charge corresponding to the target state of charge range. In this way, by limiting the state of charge of the calibrated battery within the target state of charge range, the accuracy of battery SOC calibration can be further improved.

[0161] In some embodiments, the above step S203 may include the following step S501:

[0162] Step S501: When the rate of change of the open-circuit voltage of the battery with respect to the state of charge within the target state of charge range exceeds the rate-of-change threshold, calibrate the current state of charge of the battery.

[0163] In this way, the rate of change of the open-circuit voltage with respect to the state of charge exceeding the rate-of-change threshold can indicate that the change of the OCV of the battery with respect to the SOC is relatively obvious. Considering that the first model terminal voltage is determined based on the state of charge of the battery, in the case where the change of the OCV with respect to the SOC is not obvious, the accuracy of the first model terminal voltage determined based on the OCV will be reduced, and further reduce the accuracy of determining whether to calibrate the current state of charge based on the first voltage error corresponding to the first model terminal voltage.

[0164] Exemplarily, when the rate of change of the open-circuit voltage of the battery with respect to the state of charge exceeds a rate-of-change threshold, the target state-of-charge range may correspond to at least one of SOC being less than 30%, SOC being greater than 60% and less than 70%, SOC being greater than 95%, etc.

[0165] In the embodiments of the present application, when the rate of change of the open-circuit voltage of the battery with respect to the state of charge within the target state-of-charge range exceeds the rate-of-change threshold, the current state of charge of the battery is calibrated. In this way, considering that when the rate of change of the open-circuit voltage with respect to the state of charge does not exceed the rate-of-change threshold, the rate of change of the open-circuit voltage with respect to the state of charge is usually small (for example, the OCV corresponding to the state of charge of the battery is in the plateau region). In this case, there will be a large error in inversely deriving the upper and lower limits of SOC based on the upper and lower limits of OCV and the corresponding relationship between SOC and OCV, and it is easy to have the problem of inaccurate calibration. Therefore, calibrating the SOC when the rate of change of the open-circuit voltage of the battery with respect to the state of charge within the target state-of-charge range exceeds the rate-of-change threshold can reduce the inaccurate calibration caused by the OCV being in the plateau region, and improve the accuracy and referenceability of the calibration result.

[0166] In some embodiments, the above step S101 may include the following step S601:

[0167] Step S601: Collect the first measured terminal voltages corresponding to multiple moments within the target state-of-charge change interval of the battery and the first operating condition indicators corresponding to each of the first measured terminal voltages.

[0168] Here, the target state-of-charge change interval may be an interval in which the state of charge of the battery changes during or after use.

[0169] For example, when the SOC of the battery changes from 15% to 24% during or after use, the target state-of-charge change interval may include the complete interval in which the SOC changes from 15% to 24%, that is, a 9% change interval.

[0170] Again, for example, when the SOC of the battery changes from 15% to 24% during or after use, the target state-of-charge change interval may include each 3% change interval during the process in which the SOC changes from 15% to 24%, and may include at least one of interval segments such as 15% to 18%, 16% to 19%, 18% to 21%, 21% to 24%, etc.

[0171] The above step S103 may include the following steps S602 to S604:

[0172] Step S602: Calculate the average value of the first measured terminal voltages collected at multiple moments within the target state-of-charge change interval to obtain the average measured terminal voltage.

[0173] In some embodiments, the voltage of the first measurement terminal may be collected multiple times at the same or different time intervals.

[0174] Step S603: Calculate the average of the multiple first model terminal voltages corresponding to the multiple first measurement terminal voltages to obtain the average model terminal voltage.

[0175] Step S604: Determine the difference between the average model terminal voltage and the average measurement terminal voltage as the first voltage error.

[0176] It can be understood that the “(V t1 –V t2 )” in the above formulas (7) to (9) can be replaced by the first voltage error obtained based on the difference between the average model terminal voltage and the average measurement terminal voltage in step S604.

[0177] In the embodiments of the present application, within the target state of charge change interval, the first measurement terminal voltages corresponding to different moments are collected multiple times, as well as the first operating condition indicators corresponding to the respective first measurement terminal voltages; the average of the multiple first measurement terminal voltages collected within the target state of charge change interval and the first model terminal voltages corresponding to the multiple first measurement terminal voltages is calculated; the difference between the obtained average model terminal voltage and the average measurement terminal voltage is determined as the first voltage error. In this way, based on the average values of the first measurement terminal voltage and the first model terminal voltage within the state of charge change interval, the influence of abnormal data on determining the first voltage error can be reduced, and the accuracy and referenceability of the first voltage error can be improved.

[0178] In some embodiments, the first operating condition indicator includes temperature and / or current rate, and the calibration method for the state of charge may further include at least one of the following steps S701 to S702:

[0179] Step S701: When the first operating condition indicator includes temperature and the minimum temperature within the target state of charge change interval is not less than the minimum temperature threshold, it is determined that the first operating condition indicator meets the target operating condition.

[0180] Here, considering that the battery temperature may abnormally decrease within the target state of charge change interval, determining that the minimum temperature among the temperatures corresponding to multiple moments within the target state of charge change interval is not less than the minimum temperature threshold can reduce the influence of abnormal low-temperature data on determining whether the first operating condition indicator meets the target operating condition, and improve the accuracy and stability of determining that the first operating condition indicator meets the target operating condition.

[0181] Step S702: When the first operating condition indicator includes current rate and the average current rate within the target state of charge change interval is not greater than the average current rate threshold, it is determined that the first operating condition indicator meets the target operating condition.

[0182] Here, the current rate can be a working condition index characterizing the charge and discharge ability of the battery.

[0183] In some embodiments, the current rate can be determined based on the current and rated capacity of the battery.

[0184] The average current rate can be the average value of the current rates collected at multiple moments within the target state of charge change interval. Considering that the current rates at different moments within the target state of charge change interval may fluctuate, determining that the average current rate within the target state of charge change interval is not greater than the average current rate threshold can reduce the influence of the current rate fluctuations at different moments on determining whether the first working condition index meets the target working condition, and improve the accuracy and stability of determining that the first working condition index meets the target working condition.

[0185] It can be understood that the above method for calibrating the state of charge may further include determining that the first working condition index meets the target working condition when the first working condition index includes temperature and current rate, the minimum temperature within the target state of charge change interval is not less than the minimum temperature threshold, and the average current rate within the target state of charge change interval is not greater than the average current rate threshold. In this way, by combining two different working condition indexes, the accuracy and stability of determining that the first working condition index meets the target working condition can be further improved.

[0186] In some embodiments, the above method for calibrating the state of charge may further include the following steps S801 to S802:

[0187] Step S801, determine at least one candidate working condition and the corresponding candidate voltage error range for each candidate working condition; the candidate voltage error range characterizes the error range of the model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets the target credibility condition.

[0188] In some embodiments, the use test of the electrical equipment can be pre - carried out to collect the operation data of the electrical equipment in different scenarios; among them, the operation data may include, but is not limited to, current, current rate, voltage, temperature, SOC, etc.

[0189] For example, through actual vehicle testing of a battery-powered vehicle, operating data of the vehicle can be collected under different scenarios such as high-speed conditions and urban conditions; based on the operating data corresponding to each scenario, the model terminal voltage determined based on the equivalent circuit model under each scenario can be determined; based on the measured terminal voltage corresponding to each scenario, the voltage error of the model terminal voltage under each scenario can be determined; based on the operating data corresponding to each scenario, the operating conditions under which the voltage error of the model terminal voltage is within a preset threshold range can be determined as candidate operating conditions; and the range of the voltage error of the model terminal voltage corresponding to the operating data under the candidate operating conditions can be determined as the candidate voltage error range corresponding to the candidate operating conditions.

[0190] Step S802: Determine the target operating condition corresponding to the reference voltage error range from at least one candidate operating condition.

[0191] Here, based on the correspondence between the candidate operating conditions and the corresponding candidate voltage error ranges, the candidate operating condition corresponding to the candidate voltage error range that is the same as the reference voltage error range can be determined as the target operating condition.

[0192] In the embodiments of the present application, by determining at least one candidate operating condition and the candidate voltage error range corresponding to each candidate operating condition, the target operating condition corresponding to the reference voltage error range can be quickly and accurately determined from at least one candidate operating condition.

[0193] In some embodiments, the above step S801 may include the following steps S901 to S903:

[0194] Step S901: Obtain at least one second measured terminal voltage of the battery during the target test process, and the corresponding second operating condition index and measured state of charge for each second measured terminal voltage.

[0195] Here, the target test process may include the use test process of the electrical device.

[0196] In some embodiments, during the target test process, the battery may be in a used state or a non-used state.

[0197] The second operating condition index can be used to characterize the working environment and / or working state of the battery at the second measured terminal voltage, and can be the operating condition index collected when measuring the second measured terminal voltage.

[0198] The measured state of charge can be the state of charge of the battery collected when measuring the second measured terminal voltage.

[0199] Step S902: For each second measured terminal voltage, based on the equivalent circuit model and the corresponding measured state of charge, determine the second model terminal voltage of the battery under the corresponding second operating condition index, and based on the second measured terminal voltage, determine the second voltage error of the second model terminal voltage.

[0200] Here, the second model terminal voltage can be the battery terminal voltage estimated based on the model parameters of the equivalent circuit model and the state of charge of the battery under the second operating condition index.

[0201] Exemplarily, the process of determining the second voltage error Q' can refer to formula (10):

[0202] (10);

[0203] Where, V t3 is the second model terminal voltage, and V t4 is the second measured terminal voltage.

[0204] Step S903: Based on the second operating condition index corresponding to each second measured terminal voltage and the corresponding second voltage error, determine at least one candidate operating condition and the candidate voltage error range with a corresponding relationship.

[0205] Here, by screening the second voltage errors, the second operating condition indexes corresponding to the second voltage errors within the first voltage error range can be determined as candidate operating conditions, and the first voltage error range can be determined as the candidate voltage error range corresponding to this candidate operating condition.

[0206] Exemplarily, the second operating condition indexes corresponding to each second voltage error when at least one second voltage error is within [-30 mV, 30 mV] can be sorted out as candidate operating conditions. For example, when the second voltage error is within [-30 mV, 30 mV], if the minimum temperature in each second operating condition index is greater than 30 degrees, then when the candidate voltage error range is [-30 mV, 30 mV], the corresponding candidate operating condition can be that the minimum temperature is greater than 30 degrees.

[0207] In the embodiments of the present application, at least one second measured terminal voltage collected during a target test process, and the corresponding second operating condition index and measured state of charge for each second measured terminal voltage are utilized; the second model terminal voltage of the battery under the corresponding second operating condition index is determined, and based on the second measured terminal voltage, the second voltage error of the second model terminal voltage is determined; further, based on the second operating condition index corresponding to each second measured terminal voltage and the corresponding second voltage error, at least one candidate operating condition and a candidate voltage error range with a corresponding relationship are determined. In this way, based on the corresponding relationship between at least one second voltage error and the second operating condition index, the accuracy of finding the candidate operating condition and the corresponding candidate voltage error range can be improved, and further, the accuracy of determining the target operating condition from the candidate operating conditions based on the reference voltage error range can be improved.

[0208] Lithium iron phosphate (LFP) batteries have become an ideal power source and energy source for electric vehicles due to their long lifespan, good safety performance, and low cost. However, lithium iron phosphate batteries have the problem that the open-circuit voltage does not change significantly with the state of charge when it is in the plateau region, and it is difficult to accurately estimate the state of charge when the open-circuit voltage is in the plateau region.

[0209] Moreover, as the battery is used, the SOC deviation will gradually accumulate. If the long-term accumulated SOC deviation is not corrected, it will lead to undesirable phenomena such as overvoltage or undervoltage of the battery.

[0210] On this basis, taking the scenario of calibrating the state of charge of a lithium iron phosphate battery as an example, the embodiments of the present application provide a method for calibrating the state of charge to illustrate the method for calibrating the state of charge provided by the embodiments of the present application. As Figure 2 shown, the method for calibrating the state of charge includes the following steps S1001 to step S1006:

[0211] Step S1001: Establish a model for the lithium iron phosphate battery.

[0212] Here, an open-loop model is established for the lithium iron phosphate battery.

[0213] In implementation, the model may include a second-order RC equivalent circuit model.

[0214] Step S1002: Through the OCV test experiment and the pulsed current test experiment, using an optimization algorithm, complete the offline identification process of the parameters.

[0215] Step S1003: Screen out candidate operating conditions with the second voltage error within the candidate voltage error range by trying various operating condition combinations.

[0216] Exemplarily, the current I of the battery under scenarios such as high-speed conditions and urban conditions can be collected through the actual vehicle test of a car using the battery t0 to I tn , voltage U t0 to U tn , temperature T0 to T n and SOC0 to SOC n and other data; taking parameters such as current, temperature, and SOC as the input of the model in step S1001, and taking the calculated model terminal voltage as the output. The calculation process can refer to formula (1). Among them, the calculated model terminal voltage can correspond to the second model terminal voltage in the calibration method of the state of charge mentioned above; calculate the second voltage error within each 3% SOC change interval. The second voltage error is determined based on the difference between the average value of the second measured terminal voltages collected at multiple moments and the average value of the second model terminal voltages corresponding to each second measured terminal voltage; and count the second operating condition indicators within the 3% SOC change interval, such as the average current rate of the 3% SOC change segment, the minimum temperature of the 3% SOC change segment, etc.; by combining multiple second operating condition indicators with the second voltage error within [-30 mV, 30 mV], candidate operating condition conditions are screened out, such as the average current rate is less than 0.5 C and the minimum temperature is greater than 30 degrees, and [-30 mV, 30 mV] is used as the candidate voltage error range corresponding to the candidate operating condition conditions.

[0217] Step S1004. During the operation of the battery, determine the first operating condition indicator and the corresponding first voltage error.

[0218] Exemplarily, during the operation of the battery, the average measured terminal voltage and the average model terminal voltage within each 3% SOC change interval can be calculated to obtain the first voltage error within each 3% SOC change interval, and at the same time, the average current rate and the minimum temperature corresponding to each 3% SOC change interval are determined; when the average current rate corresponding to the 3% SOC change interval is less than 0.5 C and the minimum temperature is greater than 30 degrees, it can be determined that the first voltage error within the 3% SOC change interval is within [-30 mV, 30 mV], that is, within the reference voltage error range.

[0219] Here, when the first voltage error is not within the reference voltage error range, steps S1005 to S1006 are executed.

[0220] Step S1005. Calculate the target open-circuit voltage range.

[0221] Step S1006. Based on the change curve between OCV and SOC and the target open-circuit voltage range, correct the current state of charge of the battery.

[0222] Here, the variation curve between OCV and SOC can correspond to the first correspondence relationship in the above-mentioned calibration method of the state of charge.

[0223] Exemplarily, when the current SOC of the battery is 30% and the OCV corresponding to the current SOC is 3257 mV, the average model terminal voltage is 3104 mV, the corresponding average measured terminal voltage is 3051 mV, the upper limit of the OCV corresponding to the unbiased SOC calculated by formula 8 is 3234 mV, and the lower limit of the OCV corresponding to the unbiased SOC is 3174 mV. The upper limit of the target state of charge range obtained according to the OCV-SOC curve is 24%, and the lower limit of the target state of charge range is 6%. Since the current SOC is greater than 24%, the SOC is corrected to 24%.

[0224] In the embodiments of the present application, during the operation of the battery, a first operating condition index and a corresponding first voltage error are determined; when the first voltage error is not within the reference voltage error range corresponding to the first operating condition index, based on the variation curve between OCV and SOC and the target open-circuit voltage range, the current state of charge of the battery is corrected. In this way, when there are deviations such as the current charge state of the battery being too high or too low, the state of charge of the battery can be calibrated, reducing the problems of overvoltage or undervoltage of the battery caused by SOC deviation, and further improving the device performance of the electrical device supported by the battery.

[0225] The embodiments of the present application provide a calibration device for the state of charge, as Figure 3 shown. The calibration device 30 for the state of charge includes:

[0226] An acquisition module 31, configured to acquire a first measured terminal voltage of the battery and a first operating condition index corresponding to the first measured terminal voltage;

[0227] A first determination module 32, configured to determine a first model terminal voltage corresponding to the battery under the first operating condition index based on the equivalent circuit model of the battery and the current state of charge of the battery;

[0228] A second determination module 33, configured to determine a first voltage error of the first model terminal voltage based on the first measured terminal voltage;

[0229] A calibration module 34, configured to calibrate the current state of charge of the battery based on the first voltage error and the reference voltage error range when the first operating condition index meets the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition; the reference voltage error range represents the error range of the model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets the target credibility condition.

[0230] In some embodiments, the calibration module may further be configured to: determine a target voltage error range based on the first voltage error and the reference voltage error range; the upper limit of the target voltage error range is determined based on the difference between the first voltage error and the lower limit of the reference voltage error range, and the lower limit of the target voltage error range is determined based on the difference between the first voltage error and the upper limit of the reference voltage error range; determine a target state of charge range of the battery based on the target voltage error range and the current state of charge of the battery; and calibrate the current state of charge of the battery based on the target state of charge range.

[0231] In some embodiments, the calibration module may further be configured to: query a first correspondence based on the current state of charge of the battery to obtain an estimated value of the current open-circuit voltage of the battery; the first correspondence represents the correspondence between the open-circuit voltage and the state of charge of the battery; determine a target open-circuit voltage range of the battery based on the estimated value and the target voltage error range; and determine a target state of charge range of the battery based on the target open-circuit voltage range and the first correspondence.

[0232] In some embodiments, the calibration module may further be configured to: when the current state of charge of the battery is greater than a first threshold, calibrate the state of charge of the battery to the first threshold; the first threshold includes the upper limit of the target state of charge range; when the current state of charge of the battery is less than a second threshold, calibrate the state of charge of the battery to the second threshold; the second threshold includes the lower limit of the target state of charge range.

[0233] In some embodiments, the calibration module may further be configured to: calibrate the current state of charge of the battery when the change rate of the open-circuit voltage of the battery with respect to the state of charge within the target state of charge range exceeds a change rate threshold.

[0234] In some embodiments, the acquisition module may further be configured to: collect a first measured terminal voltage corresponding to each of multiple moments within a target state of charge change interval of the battery and a first operating condition index corresponding to each of the first measured terminal voltages.

[0235] The second determination module may further be configured to: calculate an average measured terminal voltage by averaging the first measured terminal voltages collected at multiple moments within the target state of charge change interval; calculate an average model terminal voltage by averaging multiple first model terminal voltages corresponding to the multiple first measured terminal voltages; and determine the difference between the average model terminal voltage and the average measured terminal voltage as the first voltage error.

[0236] In some embodiments, the first operating condition index includes temperature and / or current rate. The calibration device for the state of charge may further include a third determination module for at least one of the following: when the first operating condition index includes temperature and the minimum temperature within the target state of charge change range is not less than the minimum temperature threshold, determining that the first operating condition index meets the target operating condition; when the first operating condition index includes current rate and the average current rate within the target state of charge change range is not greater than the average current rate threshold, determining that the first operating condition index meets the target operating condition.

[0237] In some embodiments, the calibration device for the state of charge may further include a fourth determination module for: determining at least one candidate operating condition and a corresponding candidate voltage error range for each candidate operating condition; the candidate voltage error range characterizing the error range of the model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets the target credibility condition; and determining the target operating condition corresponding to the reference voltage error range from the at least one candidate operating condition.

[0238] In some embodiments, the fourth determination module may further be configured to: obtain at least one second measured terminal voltage of the battery during a target test process, and a corresponding second operating condition index and measured state of charge for each second measured terminal voltage; for each second measured terminal voltage, determine a second model terminal voltage of the battery under the corresponding second operating condition index based on the equivalent circuit model and the corresponding measured state of charge, and determine a second voltage error of the second model terminal voltage based on the second measured terminal voltage; and determine at least one candidate operating condition and a candidate voltage error range having a corresponding relationship based on the second operating condition index corresponding to each second measured terminal voltage and the corresponding second voltage error.

[0239] An embodiment of the present application provides a computer program, including computer-readable code. When the computer-readable code runs on a computer device, a processor in the computer device executes to implement some or all of the steps in the above method for calibrating the state of charge.

[0240] An embodiment of the present application provides a computer program product, including a computer program or instruction. When the computer program or instruction is executed by a processor, some or all of the steps in the above method for calibrating the state of charge are implemented.

[0241] An embodiment of the present application provides a computer-readable storage medium storing a computer program that can be executed by a processor to implement the above method for calibrating the state of charge.

[0242] An embodiment of the present application provides a battery system, such as Figure 4 shown. The battery system 40 includes at least one battery 41 and a battery management system 42, and the battery management system 42 is used to implement some or all of the steps in the above-mentioned state of charge calibration method.

[0243] An embodiment of the present application provides an electrical device, such as Figure 5 shown. The electrical device 50 includes the battery system 40 in the above-mentioned embodiment of the application.

[0244] Here, the electrical device may include, but is not limited to, automobiles, airplanes, electric bicycles, electric motorcycles, electric speedboats, ships, etc.

[0245] In the description of the present application, the descriptions with reference to terms such as "in one embodiment", "in some embodiments", "in other embodiments", "in still other embodiments", or "exemplary", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without conflict, those skilled in the art can combine the different embodiments or examples described in the present application and the features of different embodiments or examples.

[0246] The above are only exemplary embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A method for calibrating a state of charge, characterized in that: The calibration method comprises: Acquire a first measurement terminal voltage of a battery and a first operating condition indicator corresponding to the first measurement terminal voltage; Determining a first model terminal voltage corresponding to the battery under the first operating condition indicator based on an equivalent circuit model of the battery and a current state of charge of the battery; determining a first voltage error of the first model terminal voltage based on the first measurement terminal voltage; When the first operating condition indicator meets the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition, the current state of charge of the battery is calibrated based on the first voltage error and the reference voltage error range; the reference voltage error range represents the error range of the model terminal voltage determined based on the equivalent circuit model when the operating condition indicator of the battery meets the target operating condition and the state of charge of the battery meets the target trustworthy condition.

2. The method for calibrating the state of charge according to claim 1, characterized in that: The calibrating the current state of charge of the battery based on the first voltage error and the reference voltage error range includes: Based on the first voltage error and the reference voltage error range, a target voltage error range is determined; the upper limit of the target voltage error range is determined based on the difference between the first voltage error and the lower limit of the reference voltage error range, and the lower limit of the target voltage error range is determined based on the difference between the first voltage error and the upper limit of the reference voltage error range; Determining a target state of charge range of the battery based on the target voltage error range and the current state of charge of the battery; Based on the target state of charge range, the current state of charge of the battery is calibrated.

3. The method for calibrating the state of charge according to claim 2, characterized in that: The step of determining a target state of charge range of the battery based on the target voltage error range and the current state of charge of the battery includes: Based on the current state of charge of the battery, query a first corresponding relationship to obtain an estimated value of the current open circuit voltage of the battery; the first corresponding relationship represents a corresponding relationship between the open circuit voltage and the state of charge of the battery; Determining a target open circuit voltage range of the battery based on the estimated value and the target voltage error range; A target state of charge range of the battery is determined based on the target open circuit voltage range and the first corresponding relationship.

4. The method for calibrating the state of charge according to claim 2, characterized in that: The calibrating the current state of charge of the battery based on the target state of charge range includes: When the current state of charge of the battery is greater than a first threshold, calibrating the state of charge of the battery to the first threshold; the first threshold includes an upper limit of the target state of charge range; When the current state of charge of the battery is less than a second threshold, the state of charge of the battery is calibrated to the second threshold; the second threshold includes a lower limit of the target state of charge range.

5. The method for calibrating the state of charge according to claim 2, characterized in that: The calibrating the current state of charge of the battery based on the target state of charge range includes: When the rate of change of the open circuit voltage of the battery with the state of charge exceeds a rate of change threshold within the target state of charge range, the current state of charge of the battery is calibrated.

6. The method for calibrating the state of charge according to claim 1, characterized in that: The obtaining of a first measurement terminal voltage of the battery and a first operating condition indicator corresponding to the first measurement terminal voltage includes: Collecting first measurement terminal voltages of the battery corresponding to multiple moments within a target state of charge variation interval and first operating condition indicators corresponding to each of the first measurement terminal voltages; The determining, based on the first measurement terminal voltage, a first voltage error of the first model terminal voltage comprises: averaging the first measurement terminal voltages collected at multiple times within the target state of charge change interval to obtain an average measurement terminal voltage; averaging a plurality of the first model terminal voltages respectively corresponding to a plurality of the first measurement terminal voltages to obtain an average model terminal voltage; The difference between the average model terminal voltage and the average measurement terminal voltage is determined as the first voltage error.

7. The method for calibrating the state of charge according to claim 6, characterized in that: The first operating condition indicator includes temperature and / or current ratio, and the calibration method further includes at least one of the following: In a case where the first operating condition indicator includes temperature and a minimum temperature within the target state of charge variation interval is not less than a minimum temperature threshold, determining that the first operating condition indicator satisfies the target operating condition; When the first operating condition indicator includes a current multiplier and the average current multiplier within the target state of charge change interval is not greater than an average current multiplier threshold, it is determined that the first operating condition indicator meets the target operating condition.

8. The method for calibrating the state of charge according to any one of claims 1 to 7, characterized in that: The calibration method further comprises: Determine at least one candidate operating condition and a candidate voltage error range corresponding to each candidate operating condition; the candidate voltage error range represents an error range of a model terminal voltage determined based on the equivalent circuit model when the state of charge of the battery meets a target trustworthy condition; The target operating condition corresponding to the reference voltage error range is determined from the at least one candidate operating condition.

9. The method for calibrating the state of charge according to claim 8, characterized in that: The determining of at least one candidate operating condition and a candidate voltage error range corresponding to each candidate operating condition includes: Acquire at least one second measurement terminal voltage of the battery during a target test, and a second operating condition indicator and a measured state of charge corresponding to each second measurement terminal voltage; For each second measurement terminal voltage, determine a second model terminal voltage of the battery under a corresponding second operating condition indicator based on the equivalent circuit model and the corresponding measured state of charge, and determine a second voltage error of the second model terminal voltage based on the second measurement terminal voltage; Based on the second operating condition indicators corresponding to each of the second measuring terminal voltages and the corresponding second voltage errors, at least one of the candidate operating condition and the candidate voltage error range having a corresponding relationship is determined.

10. A charge state calibration device, characterized in that: The calibration device comprises: An acquisition module, used to acquire a first measurement terminal voltage of the battery and a first operating condition indicator corresponding to the first measurement terminal voltage; A first determining module, configured to determine a first model terminal voltage corresponding to the battery under the first operating condition indicator based on an equivalent circuit model of the battery and a current state of charge of the battery; A second determining module, configured to determine a first voltage error of the first model terminal voltage based on the first measurement terminal voltage; A calibration module is used to calibrate the current state of charge of the battery based on the first voltage error and the reference voltage error range when the first operating condition indicator meets the target operating condition and the first voltage error is not within the reference voltage error range corresponding to the target operating condition; the reference voltage error range represents the error range of the model terminal voltage determined based on the equivalent circuit model when the operating condition indicator of the battery meets the target operating condition and the state of charge of the battery meets the target trustworthy condition.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps in the method according to any one of claims 1 to 9 are implemented.

12. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the steps in the method according to any one of claims 1 to 9 are implemented.

13. A battery system, characterized in that: The invention comprises at least one battery and a battery management system; the battery management system is used to implement the steps in the method according to any one of claims 1 to 9.

14. An electrical device, characterized in that: Comprising the battery system as claimed in claim 13.

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