Current calibration method, battery management system, battery equipment and power utilization device

Abstract

The current calibration method comprises the following steps: acquiring a plurality of current samples, each current sample comprising a target charging current and an actual charging current, defining the target charging current as a charging request current sent to a charging device in response to a battery device, and a charging current transmitted to the battery device by the charging device, defining the actual charging current as the charging current sampled when the battery equipment is charged; a target charging current calibration coefficient is determined based on the plurality of current samples.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a current calibration method, a battery management system, a battery device and an electrical device. Background Art

[0002] With the development of new energy technologies, battery equipment is being applied in more and more fields. For example, battery equipment is used as a power source to provide power to electrical devices, thereby reducing the use of non-renewable resources. The battery management system in the battery equipment manages the charge and discharge status of the battery equipment based on the sampled current, voltage or temperature. In this process, the sampling accuracy of current, voltage or temperature is required to be high.

[0003] In addition to using high-precision sampling chips, the current calibration coefficient is stored in the battery management system before the battery device leaves the factory to calibrate the sampled current. At present, after the battery device leaves the factory, the current calibration coefficient is easily lost or the calibration accuracy is poor. Summary of the invention

[0004] In view of this, some embodiments of the present application provide a current calibration method, a battery management system, a battery device and an electrical device. The current calibration method enables the current calibration coefficient to be adaptively learned and corrected to maintain a high calibration accuracy, thereby improving the current accuracy and reducing the cost of returning to the factory for repairs due to insufficient accuracy.

[0005] In the first aspect, some embodiments of the present application provide a current calibration method, first obtaining multiple current samples, and then determining a target charging current calibration coefficient based on the multiple current samples. Each current sample includes a target charging current and an actual charging current, and the target charging current is defined as the charging current transmitted by the charging device to the battery device in response to the charging request current sent by the battery device to the charging device, and the actual charging current is defined as the charging current sampled when the battery device is charged.

[0006] In the above embodiment, the target charging current transmitted by the charging device to the battery device is the real charging current output by the charging device to the battery device, and the actual charging current is the sampled charging current obtained by the battery device sampling the target charging current. It can be seen that the current sample includes the real charging current and the sampled charging current, and the relationship between the two reflects the calibration coefficient, so as to achieve the determination of the target charging current calibration coefficient based on multiple current samples. That is, with the help of the target charging current (real charging current) output by the charging device, the calibration coefficient of the actual charging current (sampled charging current) is adaptively learned and corrected to maintain a high calibration accuracy. In this way, the corrected target charging current calibration coefficient adaptively matches the current situation of the battery device (such as ambient temperature), so as to calibrate a charging current with higher accuracy, which is conducive to accurately estimating electrical parameters (such as SOC) and performing early warning work based on charging current. In addition, the calibration coefficient is adaptively learned and corrected, and there is no need to return to the factory for calibration, which reduces the cost of returning to the factory for repair due to insufficient accuracy, so that the battery equipment has the advantages of high reliability, low after-sales cost, and easy maintenance.

[0007] In some embodiments, the charging request current includes: a first charging request current, and a charging request current that increases with the first step until the last charging request current is greater than or equal to the first current threshold; wherein the first current threshold is the maximum value of the allowed charging current of the battery device. That is, the range of the charging request current covers the smaller first charging request current to the maximum value of the allowed charging current, so that multiple current samples cover the small current charging situation, the allowed large current charging situation, and the intermediate current charging situation that increases gradually with the first step. In this way, multiple current samples are rich and comprehensive, which is conducive to improving the accuracy of the target charging current calibration coefficient.

[0008] In some embodiments, determining the target charging current calibration coefficient based on the plurality of current samples includes: performing function fitting on the target charging current and the actual charging current to obtain function parameters, and defining the function parameters as the target charging current calibration coefficient.

[0009] In this embodiment, a calibration coefficient is reflected based on the relationship between multiple groups of target charging currents and actual charging currents. The actual charging current is used as the independent variable and the target charging current is used as the dependent variable. Function fitting is performed to obtain function parameters, which characterize the functional relationship between the two. The function parameters are then used as target charging current calibration coefficients to obtain accurate target charging current calibration coefficients.

[0010] In some embodiments, the current calibration method further includes: in response to the charging request current being less than or equal to a second current threshold, calculating a first absolute value of a difference between the target charging current and the actual charging current; in response to the absolute value of the first difference exceeding the current sampling accuracy of the battery device for the first consecutive number of times, triggering the current calibration method.

[0011] In this embodiment, the charging request current is less than or equal to the second current threshold, indicating that the battery device is charged with a small current. The absolute value of the first difference between the target charging current and the actual charging current reflects the gap between the sampled charging current and the real charging current. The larger the absolute value of the first difference, the higher the risk of low calibration accuracy. Therefore, in the case of small current charging, the first trigger condition for triggering the current calibration method is set, that is, the absolute value of the first difference exceeds the current sampling accuracy of the battery device for the first consecutive number of times, so as to trigger the current calibration method and perform adaptive learning correction on the current charging current calibration coefficient. On the one hand, it is conducive to improving the calibration accuracy; on the other hand, setting the first number effectively reduces frequent triggering or false triggering, thereby reducing program errors.

[0012] In some embodiments, the aforementioned current calibration method is triggered in response to the absolute value of the first difference exceeding the current sampling accuracy of the battery device for the first consecutive time, including: in response to the absolute value of the first difference exceeding the current sampling accuracy of the battery device for the first consecutive time and the charging request current reaching a third current threshold, the current calibration method is triggered; wherein the third current threshold is K times the maximum value of the allowable charging current of the battery device, 0.5≤K≤1.

[0013] In this embodiment, in the case of low current charging, a second trigger condition is set on the basis of the above-mentioned first trigger condition, that is, the charging request current reaches the third current threshold, triggering the current calibration method. Among them, the third current threshold is K times (0.5≤K≤1) the maximum value of the allowable charging current of the battery device, reflecting the range of the charging current. That is, the current calibration method is triggered when the range of the charging current reaches the third current threshold, so that the current sample covers a wider range, which is conducive to improving the accuracy of the target charging current calibration coefficient, and improving the calibration accuracy and calibration range.

[0014] In some embodiments, the current calibration method further includes: in response to a charging request current being greater than a second current threshold, calculating a first absolute value of a difference between a target charging current and an actual charging current, and a first ratio between the absolute value of the first difference and the target charging current; in response to the first ratio exceeding the first ratio threshold for a second consecutive number of times, triggering the current calibration method.

[0015] In this embodiment, the charging request current is greater than the second current threshold, indicating that the battery device is charged with a large current. The absolute value of the first difference between the target charging current and the actual charging current reflects the gap between the sampled charging current and the actual charging current. The larger the absolute value of the first difference, the higher the risk of low calibration accuracy. Therefore, in the case of high current charging, the third trigger condition for triggering the current calibration method is set, that is, the first ratio (the absolute value of the first difference to the target charging current) exceeds the first ratio threshold for a second consecutive number of times, so as to trigger the current calibration method, and adaptively learn and correct the charging current calibration coefficient, which is beneficial to improve the calibration accuracy. In addition, the trigger threshold in the case of high current is the first ratio threshold, which is more relaxed, adapted to the actual charging situation, and is beneficial to calibration accuracy. In addition, setting the second number effectively reduces frequent triggering or false triggering, thereby reducing program errors.

[0016] In some embodiments, the aforementioned response to the first ratio exceeding the first ratio threshold for the second consecutive number of times, triggering the current calibration method includes: in response to the first ratio exceeding the first ratio threshold for the second consecutive number of times and the charging request current reaching a third current threshold, triggering the current calibration method; wherein the third current threshold is K times the maximum value of the allowable charging current of the battery device, 0.5≤K≤1.

[0017] In this embodiment, in the case of high current charging, a fourth trigger condition is set on the basis of the third trigger condition, that is, the charging request current reaches the third current threshold, triggering the current calibration method. The third current threshold is K times (0.5≤K≤1) the maximum value of the allowable charging current of the battery device, reflecting the range of the charging current. That is, the current calibration method is triggered when the range of the charging current reaches the third current threshold, so that the current sample covers a wider range, which is conducive to improving the accuracy of the target charging current calibration coefficient, and improving the calibration accuracy and calibration range.

[0018] In some embodiments, the current calibration method also includes: calibrating the actual charging current using a target charging current calibration coefficient to obtain a calibrated charging current; in response to the calibrated charging current being less than or equal to a fifth current threshold, calculating a second absolute value of the difference between the calibrated charging current and the target charging current; in response to the absolute value of the second difference not exceeding the current sampling accuracy of the battery device, correcting the current charging current calibration coefficient using the target charging current calibration coefficient, and storing the target charging current calibration coefficient in a memory.

[0019] In this embodiment, the calibration charging current is less than or equal to the fifth current threshold, indicating that the battery device is charged with a small current. The absolute value of the second difference between the calibration charging current and the target charging current reflects the calibration accuracy. The smaller the absolute value of the second difference, the greater the calibration accuracy of the target charging current calibration coefficient. Therefore, in the case of small current charging, the absolute value of the second difference does not exceed the current sampling accuracy of the battery device, indicating that the target charging current calibration coefficient has a higher calibration accuracy. In this way, the target charging current calibration coefficient is verified and stored after the verification is passed, which is conducive to ensuring that the target charging current calibration coefficient has a higher calibration accuracy.

[0020] In some embodiments, the current calibration method also includes: in response to the calibration charging current being greater than a fifth current threshold, calculating a second absolute value of the difference between the calibration charging current and the target charging current, and a second ratio between the second absolute value of the difference and the target charging current; in response to the second ratio being less than or equal to a second ratio threshold, using the target charging current calibration coefficient to correct the current charging current calibration coefficient, and storing the target charging current calibration coefficient in a memory.

[0021] In this embodiment, the calibration charging current is greater than the fifth current threshold, indicating that the battery device is charged with a large current. The absolute value of the second difference between the calibration charging current and the target charging current reflects the calibration accuracy. The smaller the absolute value of the second difference, the greater the calibration accuracy of the target charging current calibration coefficient. In the case of large current charging, the second ratio (the absolute value of the second difference to the target charging current) is less than or equal to the second ratio threshold, indicating that the target charging current calibration coefficient has a higher calibration accuracy. In this way, the target charging current calibration coefficient is verified and stored after the verification is passed, which is conducive to ensuring that the target charging current calibration coefficient has a higher calibration accuracy. In addition, the verification threshold in the case of large current is the second ratio threshold, which is more relaxed, adapted to the actual charging situation, and is conducive to the accuracy of current calibration.

[0022] In some embodiments, the aforementioned use of the target charging current calibration coefficient to correct the current charging current calibration coefficient includes: in response to the current temperature of the battery device falling into the target temperature interval, using the target charging current calibration coefficient to correct the current charging current calibration coefficient corresponding to the target temperature interval.

[0023] In this embodiment, the temperature interval has a corresponding relationship with the target charging current calibration coefficient. The target charging current calibration coefficient is adopted or updated according to the temperature interval, so that the target charging current calibration coefficient is adapted to the current temperature of the battery device, conforms to the working condition of the battery device, is more accurate, and is conducive to improving the current calibration accuracy.

[0024] In a second aspect, some embodiments of the present application provide a battery management system, including a processor and a memory, wherein the memory is used to store instructions, and the processor is used to execute instructions to implement the current calibration method in the first aspect.

[0025] In a third aspect, some embodiments of the present application provide a battery device, including a battery pack and the battery management system in the second aspect.

[0026] In a fourth aspect, some embodiments of the present application provide an electrical device, including the battery device in the third aspect.

[0027] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the structure of a battery device in some embodiments of the present application;

[0029] Figure 2 is a schematic diagram of the structure of a battery pack in some embodiments of the present application;

[0030] Figure 3 is a schematic diagram of the structure of a BMS in some embodiments of the present application;

[0031] Figure 4 is a schematic diagram of a battery pack obtaining multiple current samples in some embodiments of the present application;

[0032] Figure 5 is a schematic diagram of increasing charging request current in some embodiments of the present application;

[0033] Figure 6 is a schematic diagram of performing function fitting on multiple current samples in some embodiments of the present application;

[0034] Figure 7 is a flow chart of a current calibration method in some embodiments of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and in detail in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] The technical features involved in the various embodiments of the present application described below do not conflict with each other and can be combined with each other.

[0037] Although the device schematic diagram is divided into functional modules and the flowchart shows a logical sequence, in some cases, the steps may be divided differently from the modules in the device or may be executed in an order different from that shown in the flowchart.

[0038] When an element is referred to as being “connected to” another element, it can be directly connected to the other element, or one or more intervening elements may be present therebetween.

[0039] The terms "first", "second", etc. in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0040] In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the previously and subsequently associated objects are in an "or" relationship.

[0041] When the battery equipment is provided with charging service, the battery equipment is electrically connected to the charging equipment (such as a charging pile or a charging cabinet) to realize the charging service. Exemplarily, the battery equipment includes one or more battery packs, for example, the battery equipment of an electric bicycle includes a battery pack. The charging cabinet includes multiple charging grids, and a battery pack is placed in each charging grid, and the battery pack is electrically connected to the charging cabinet. The Battery Management System (BMS) in the battery pack samples the charging current, and performs charging control based on the sampled charging current to prevent overcharging. Similarly, when the battery equipment provides discharging service, the BMS in the battery pack samples the discharge current, and performs discharge control based on the sampled discharge current to prevent over-discharge.

[0042] However, affected by the sampling accuracy of the device, the directly sampled charge / discharge current often has a deviation or a large deviation from the actual charge / discharge current. Before the battery equipment leaves the factory, the charging current calibration coefficient is stored in the BMS of its battery pack to calibrate the sampled charging current; the discharge current calibration coefficient is stored in the BMS of its battery pack to calibrate the sampled discharge current. At present, after the battery equipment leaves the factory, the current calibration coefficient is easily lost or the calibration accuracy is poor. For example, when the ambient temperature of the electrical device where the battery equipment is used changes, the hardware storage is affected by the environment, resulting in the loss of the current calibration coefficient or inapplicability to the current environment.

[0043] Based on this, some embodiments of the present application provide a current calibration method, a battery management system, a battery device and an electrical device. The current calibration method is executed by the battery management system, so that the current calibration coefficient is adaptively learned and corrected to maintain a high calibration accuracy, thereby improving the current accuracy and reducing the cost of returning to the factory for repairs due to insufficient accuracy.

[0044] Based on the application of a battery management system (BMS) to battery equipment, in order to facilitate understanding of the role of the battery management system in the battery equipment, here, the structure of the battery equipment in some embodiments of the present application is first introduced.

[0045] Battery Equipment

[0046] Some embodiments of the present application provide a battery device 100, see Figure 1 The battery device 100 includes a battery pack 10 or a plurality of battery packs 10 connected in parallel. Each battery pack 10 is an energy module of the battery device 100 to increase the capacity and endurance of the battery device 100.

[0047] See also Figure 2 Each battery pack 10 includes: a cell module 11, which is composed of one or more cell monomers and can be charged and discharged; a switch unit 12, which is connected in series to the positive terminal side or the negative terminal side of the cell module 11 to control the flow of charging / discharging current of the cell module 11; and a battery management system (BMS) 13, which is used to control and manage the voltage, current, temperature, etc. of the battery pack 10 to prevent overcharging and over-discharging.

[0048] Among them, the switch unit 12 can be a mechanical switch element or a semiconductor switch element, which is used to control the flow of current for charging or discharging the battery cell module 11. In detail, the switch unit 12 may include: a charging switch element, which is controlled to be turned on during charging; and a discharging switch element, which is controlled to be turned on during discharging. However, this is only an example, and therefore, the switch unit 12 is not limited to MOSFET, etc., but a relay, etc. may be used instead. Among them, one or more battery cells in the battery cell module 11 may be connected in series, in parallel, or in mixed connection, which is not limited here.

[0049] The battery management system 13 is connected to the battery module 11 and can monitor data such as voltage, current, temperature, etc. of the battery module 11. Exemplarily, when the switch unit 12 is a semiconductor switch element, the battery management system 13 can measure or calculate the voltage and current of the gate, source, and drain of the semiconductor switch device. In some embodiments, the battery management system 13 includes an analog front end chip 131 (Analog Front End, AFE), which samples the charging analog signal and converts it into a digital signal through its built-in ADC to obtain a sampled charging current. In some embodiments, the sampled charging current can also be obtained by sampling a shunt resistor.

[0050] In some embodiments, the current, voltage, temperature, etc. of the battery cell module 11 may also be measured using various sensors 14 disposed adjacent to the switch unit 12 .

[0051] As an input interface for receiving the measured values ​​of the above-mentioned various parameters, the battery management system 13 may include a plurality of terminals and circuits connected to the terminals to process the input values. In addition, the battery management system 13 may control the on / off of the switch unit 12 and may be connected to the battery cell module 11 to monitor the status of the battery cell module 11.

[0052] As described above, the sampled charging current is calibrated to obtain a charging current with higher accuracy, which is beneficial for accurately estimating electrical parameters (such as SOC) and performing early warning work based on the charging current.

[0053] The battery device 100 in the present application improves the battery management system 13 in the battery pack 10, so that the battery management system 13 calibrates the sampled charging current with higher calibration accuracy.

[0054] Hereinafter, the battery management system 13 and the current calibration method performed by the battery management system 13 will be described in detail.

[0055] Battery Management System

[0056] Some embodiments of the present application provide a battery management system. Figure 3The battery management system 13 includes a memory 131 , a processor 132 , and a computer program stored in the memory 131 and executable on the processor 132 .

[0057] In some embodiments, the processor 132 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0058] The memory 131 may include a read-only memory (ROM), a random access memory 131 (RAM), a magnetic disk storage medium device, an optical storage medium device, a flash memory device, an electrical, optical or other physical / tangible memory 131 storage device. Therefore, generally, the memory 131 includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors 132), it is operable to perform the current calibration method described with reference to the following.

[0059] The processor 132 runs a computer program corresponding to the executable program code by calling the executable program code stored in the memory 131 to implement the current calibration method described below.

[0060] The BMS 13 may further include an analog front-end chip 133 and a bus 134. Figure 3 As shown, the memory 131, the processor 132, and the analog front-end chip 133 are connected and communicate with each other via a bus 134. The analog front-end chip 133 is mainly used to sample the charging current.

[0061] The bus 134 includes hardware, software, or both, coupling the components of the BMS 13 to each other. By way of example and not limitation, the bus 134 may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industrial Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a Memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VLB) bus, or other suitable buses or a combination of two or more of the above. Where appropriate, the bus may include one or more buses. Although embodiments of the present application describe and illustrate a particular bus, the present application contemplates any suitable bus or interconnect.

[0062] It should be noted that although the above BMS13 only shows the memory 131, the processor 132, and the analog front-end chip 133, in the specific implementation process, those skilled in the art should understand that the BMS13 can also include other devices necessary for normal operation. At the same time, according to specific needs, those skilled in the art should understand that the BMS13 can also include hardware devices for implementing other additional functions. In addition, those skilled in the art should understand that the BMS13 can also include only the devices necessary to implement the embodiments of the present application, and does not necessarily include Figure 3 All devices shown in .

[0063] The hardware foundation of BMS is introduced above. The current calibration method performed by BMS is introduced below.

[0064] Current calibration method

[0065] The current calibration method provided in the embodiment of the present application is implemented in a BMS having the above hardware structure.

[0066] In the embodiment of the present application, the battery device is electrically and communicatively connected to the charging device, for example, the battery pack is electrically and communicatively connected to the charging cabinet. The battery pack sends a charging request current to the charging cabinet, and the charging cabinet responds to the charging request current, provides the charging current to the battery pack, and communicates the current value of the charging current to the battery pack.

[0067] Based on the high output accuracy of the charging cabinet, the charging current transmitted by the charging cabinet to the battery pack is used as a reference for calibrating the charging current sampled by the battery pack. In some embodiments, the target charging current is defined as the charging current transmitted by the charging cabinet to the battery pack in response to the charging request current sent by the battery pack to the charging cabinet. The actual charging current is defined as the charging current sampled when the battery pack is charged.

[0068] The target charge current and the actual charge current form a current sample. Figure 4 Each time the battery pack sends a charging request current to the charging cabinet, the battery pack BMS collects an actual charging current and receives the target charging current sent by the charging cabinet, thereby obtaining a current sample. In this way, after the battery pack sends the charging request current multiple times, multiple current samples are obtained.

[0069] In some embodiments, in order to make the current sample rich and comprehensive, the charging request current sent multiple times is set, such as Figure 5 As shown, the charge request current includes a first charge request current, and increases in increments with a first step until a last charge request current is greater than or equal to a first current threshold.

[0070] Among them, the first charging request current is a smaller current value pre-set by a technician in this field. The first current threshold is the maximum value of the allowed charging current of the battery pack. In some embodiments, the maximum value of the allowed charging current is determined by the battery pack BMS based on the temperature, state of charge (SOC) or voltage of the battery pack, combined with the power state (State of Power, SOP) table. It is understandable that the BMS of the battery pack stores an SOP table, which contains the maximum charge and discharge power of the battery pack at different SOCs and different temperatures. Thus, the BMS of the battery pack can determine the maximum charging power based on the current SOC and the current temperature, and then determine the allowed charging current based on the maximum charging power and voltage. In this way, find the maximum value of the allowed charging current in the SOP table.

[0071] The first step length is a current change value preset by a person skilled in the art. When performing the current coefficient calibration, the charging request current sent for the first time is the first charging request current, the charging request current sent for the second time is the first charging request current plus the first step length, the charging request current sent for the third time is the first charging request current plus 2*the first step length, and so on, until the charging request current increases to the first current threshold.

[0072] In this embodiment, the charging request current is set in the above manner so that the range of the charging request current covers the smaller first charging request current to the maximum value of the allowed charging current, so that the multiple current samples cover the small current charging situation, the allowed large current charging situation, and the intermediate current charging situation that increases gradually with the first step length. In this way, the multiple current samples are rich and comprehensive, which is conducive to improving the accuracy of the target charging current calibration coefficient.

[0073] It is understood that in other embodiments, the charging request current includes a plurality of randomly set current values, or a current value obtained by increasing with a variable step size starting from the first charging request current. The charging request current only needs to satisfy the maximum value of the allowable charging current of the battery pack.

[0074] The target charging current transmitted by the charging cabinet to the battery pack is the real charging current output by the charging cabinet to the battery pack, and the actual charging current is the sampled charging current obtained by sampling the target charging current by the battery pack. It can be seen that the current sample includes the real charging current and the sampled charging current, and the relationship between the two reflects the calibration coefficient, thereby realizing the determination of the target charging current calibration coefficient based on multiple current samples.

[0075] In some embodiments, Figure 6 As shown, function fitting is performed on the target charging current and the actual charging current in multiple current samples to obtain function parameters, and the function parameters are defined as the target charging current calibration coefficients.

[0076] For example, the actual charging current is used as the independent variable and the target charging current is used as the dependent variable, and the least square method is used for straight-line fitting or curve fitting. In the case of straight-line fitting, the fitting obtains the functional relationship y=kx+b, where k and b are function parameters, and k and b are defined as target charging current calibration coefficients. In the case of curve fitting, the fitting obtains the functional relationship y=ax 2 +bx+c, where a, b and c are function parameters, and a, b and c will be defined as the target charging current calibration coefficients.

[0077] In this embodiment, a calibration coefficient is reflected based on the relationship between multiple groups of target charging currents and actual charging currents. The actual charging current is used as the independent variable and the target charging current is used as the dependent variable. Function fitting is performed to obtain function parameters, which characterize the functional relationship between the two. The function parameters are then used as target charging current calibration coefficients to obtain accurate target charging current calibration coefficients.

[0078] As can be seen from the above, the current calibration method in the embodiment of the present application uses the target charging current (real charging current) output by the charging cabinet to adaptively learn and correct the calibration coefficient of the actual charging current (sampled charging current) to maintain a high calibration accuracy. In this way, the corrected target charging current calibration coefficient adaptively matches the current situation of the battery pack (such as ambient temperature), thereby calibrating a charging current with higher accuracy, which is conducive to accurately estimating electrical parameters (such as SOC) and performing early warning work based on charging current. In addition, the calibration coefficient is adaptively learned and corrected, and there is no need to return to the factory for calibration, which reduces the cost of returning to the factory for repairs due to insufficient accuracy, so that the battery equipment with a battery pack has the advantages of high reliability, low after-sales cost, and easy maintenance.

[0079] It is understandable that the current calibration method is triggered when the calibration accuracy of the current charging current calibration coefficient does not meet the current accuracy condition to perform adaptive learning correction on the current charging current calibration coefficient. For example, when the difference between the actual charging current and the target charging current is greater than the corresponding threshold, it indicates that the risk of low calibration accuracy is high, and the current calibration method is triggered to correct the current charging current calibration coefficient, and the corrected charging current calibration coefficient is used to calibrate the actual charging current.

[0080] In some embodiments, the triggering condition of the current calibration method is set according to the two conditions of low current charging and high current charging. Exemplarily, the second current threshold is set, for example, the second current threshold is 3A, to distinguish between low current charging and high current charging. When the charging request current is less than or equal to the second current threshold, it means that the battery pack is charged with a low current; when the charging request current is greater than the second current threshold, it means that the battery pack is charged with a high current.

[0081] In the case of low current charging, the absolute value of the first difference between the target charging current and the actual charging current is calculated. The absolute value of the first difference reflects the gap between the sampled charging current and the actual charging current. The larger the absolute value of the first difference, the higher the risk of low calibration accuracy.

[0082] In the case of low current charging, the first trigger condition for triggering the current calibration method is set, that is, the absolute value of the first difference exceeds the current sampling accuracy of the battery pack for the first consecutive number of times, so as to trigger the current calibration method and adaptively learn and correct the current charging current calibration coefficient. Exemplarily, the first number of times is 10 times, and the current sampling accuracy of the battery pack is ≤±0.2A, that is, the absolute value of the first difference exceeds 0.2A for 10 consecutive times, then the current calibration method is triggered.

[0083] In this way, setting the first trigger condition to trigger the current calibration method and adaptively learning and correcting the current charging current calibration coefficient is beneficial to improving the calibration accuracy; on the other hand, setting the first number effectively reduces frequent triggering or false triggering, thereby reducing program errors.

[0084] In some embodiments, for the above-mentioned low-current charging, a second trigger condition is set based on the above-mentioned first trigger condition, that is, the charging request current reaches a third current threshold, triggering the current calibration method. The third current threshold is K times (0.5≤K≤1) the maximum value of the allowed charging current of the battery device, reflecting the range of the charging current. The maximum value of the allowed charging current represents the full-scale charging current.

[0085] For example, when K is 1, the third current threshold is the full-scale charging current, and when the charging request current reaches the full scale, the current calibration method is triggered. It can be understood that when the charging request current reaches the full scale, it means that the charging request current covers the first charging request current to the full scale, so that the current sample coverage is more extensive.

[0086] For example, when K is 0.9, the third current threshold is a charging current of 0.9 times the full scale, and the charging request current reaches 0.9 times the full scale, triggering the current calibration method. It can be understood that when the charging request current can reach 0.9 times the full scale, it means that the charging request current covers the first charging request current to 0.9 times the full scale, thus ensuring the extensiveness of the current sample.

[0087] In this embodiment, based on the first trigger condition (the absolute value of the first difference exceeds the current sampling accuracy of the battery pack for the first consecutive time), it is further determined whether the charging request current reaches the third current threshold, and the current calibration method is triggered when the charging current range reaches the third current threshold, so that the current sample covers a wider range, which is beneficial to improve the accuracy of the target charging current calibration coefficient, and improve the calibration accuracy and calibration range.

[0088] Similarly, in some embodiments, under high current charging conditions, the absolute value of the first difference between the target charging current and the actual charging current is calculated. The absolute value of the first difference reflects the gap between the sampled charging current and the actual charging current. The larger the absolute value of the first difference, the higher the risk of low calibration accuracy.

[0089] In the case of high current charging, the third trigger condition for triggering the current calibration method is set, that is, the first ratio (the absolute value of the first difference to the target charging current) exceeds the first ratio threshold for a second consecutive number of times to trigger the current calibration method and perform adaptive learning correction on the current charging current calibration coefficient. Exemplarily, the second number of times is 10 times, and the first ratio threshold is 2%, that is, the first ratio exceeds 2% for 10 consecutive times, then the current calibration method is triggered.

[0090] In this way, the third trigger condition is set to trigger the current calibration method, and the current charging current calibration coefficient is adaptively learned and corrected, which is conducive to improving the calibration accuracy. In addition, the trigger threshold under high current conditions is the first ratio threshold, which is more relaxed and adapted to the actual charging situation, which is conducive to calibration accuracy. In addition, the second number is set to effectively reduce frequent triggering or false triggering, thereby reducing program errors.

[0091] In some embodiments, for the above-mentioned high current charging, a fourth trigger condition is set on the basis of the above-mentioned third trigger condition, that is, the charging request current reaches the third current threshold, triggering the current calibration method. The third current threshold is K times (0.5≤K≤1) the maximum value of the allowed charging current of the battery device, reflecting the range of the charging current. The maximum value of the allowed charging current represents the full-scale charging current.

[0092] For example, when K is 1, the third current threshold is the full-scale charging current, and when the charging request current reaches the full scale, the current calibration method is triggered. It can be understood that when the charging request current reaches the full scale, it means that the charging request current covers the first charging request current to the full scale, so that the current sample coverage is more extensive.

[0093] For example, when K is 0.9, the third current threshold is a charging current of 0.9 times the full scale, and the charging request current reaches 0.9 times the full scale, triggering the current calibration method. It can be understood that when the charging request current can reach 0.9 times the full scale, it means that the charging request current covers the first charging request current to 0.9 times the full scale, thus ensuring the extensiveness of the current sample.

[0094] In this embodiment, based on the third trigger condition (the first ratio exceeds the first ratio threshold for the second consecutive number of times), it is further determined whether the charging request current reaches the third current threshold, and the current calibration method is triggered when the charging current range reaches the third current threshold, so that the current sample covers a wider range, which is beneficial to improve the accuracy of the target charging current calibration coefficient, and improve the calibration accuracy and calibration range.

[0095] After obtaining the target charging current calibration coefficient, in order to determine the accuracy of the target charging current calibration coefficient, the target charging current calibration coefficient is verified, and after verification, the target charging current calibration coefficient is used to correct the current charging current calibration coefficient. Exemplarily, the actual charging current is calibrated using the target charging current calibration coefficient to obtain a calibrated charging current. For example, the actual charging current is substituted as x into y=kx+b to obtain the calibrated charging current. Based on the difference between the calibrated charging current and the target charging current, check whether the target charging current coefficient has been verified.

[0096] In some embodiments, verification conditions are set for two situations: low current charging and high current charging. Exemplarily, a fifth current threshold is set, for example, the fifth current threshold is 2A or 3A, to distinguish between low current charging and high current charging. When the calibration charging current is less than or equal to the fifth current threshold, it means that the battery pack is charged with a low current, corresponding to the verification condition of low current charging. When the calibration charging current is greater than the fifth current threshold, it means that the battery pack is charged with a high current, corresponding to the verification condition of high current charging.

[0097] In the case of low current charging, the second absolute value of the difference between the calibration charging current and the target charging current is calculated, and the second absolute value of the difference reflects the calibration accuracy. The smaller the second absolute value of the difference, the greater the calibration accuracy of the target charging current calibration coefficient.

[0098] In the case of low current charging, the first verification condition is set: the absolute value of the second difference does not exceed the current sampling accuracy of the battery pack. For example, the current sampling accuracy of the battery pack is ≤±0.2A, that is, the absolute value of the second difference is less than or equal to 0.2A, then the target charging current coefficient meets the first verification condition. If the first verification condition is met, the target charging current calibration coefficient is used to correct the current charging current calibration coefficient, and the target charging current calibration coefficient is stored in the memory.

[0099] In this embodiment, under low current charging conditions, the absolute value of the second difference does not exceed the current sampling accuracy of the battery pack, indicating that the target charging current calibration coefficient has a high calibration accuracy. In this way, the target charging current calibration coefficient is verified and stored after verification, which is conducive to ensuring that the target charging current calibration coefficient has a high calibration accuracy.

[0100] Similarly, in some embodiments, under high current charging conditions, the second absolute value of the difference between the calibrated charging current and the target charging current is calculated, and the second absolute value of the difference reflects the calibration accuracy. The smaller the absolute value of the second difference, the greater the calibration accuracy of the target charging current calibration coefficient.

[0101] In the case of high current charging, a second verification condition is set: the second ratio between the absolute value of the second difference and the target charging current is less than or equal to the second ratio threshold. Exemplarily, the second ratio threshold is 1%, that is, the second ratio threshold is less than or equal to 1%, and the target charging current coefficient meets the second verification condition. If the second verification condition is met, the target charging current calibration coefficient is used to correct the current charging current calibration coefficient, and the target charging current calibration coefficient is stored in the memory.

[0102] In this embodiment, under high current charging conditions, the second ratio (the absolute value of the second difference to the target charging current) is less than or equal to the second ratio threshold, indicating that the target charging current calibration coefficient has a higher calibration accuracy. In this way, the target charging current calibration coefficient is verified and stored after verification, which is conducive to ensuring that the target charging current calibration coefficient has a higher calibration accuracy. In addition, the verification threshold under high current conditions is the second ratio threshold, which is more relaxed, adapted to the actual charging conditions, and is conducive to current calibration accuracy.

[0103] Considering that the operating conditions of the battery equipment include normal temperature environment (e.g., 10°C to 35°C), low temperature environment (e.g., -30°C to 10°C) or high temperature environment (e.g., 35°C to 60°C), in order to make the charging current calibration coefficient adapt to the ambient temperature, different charging current calibration coefficients are set corresponding to different environments.

[0104] In some embodiments, when performing current calibration, the target temperature interval within which the current temperature of the battery pack falls is obtained, and the target charging current calibration coefficient is used to correct the current charging current calibration coefficient corresponding to the target temperature interval. Exemplarily, if the current temperature falls into a low temperature environment, the target charging current coefficient is used to correct the current charging current calibration coefficient corresponding to the low temperature environment.

[0105] In this embodiment, the temperature interval has a corresponding relationship with the target charging current calibration coefficient. The target charging current calibration coefficient is adopted or updated according to the temperature interval, so that the target charging current calibration coefficient is adapted to the current temperature of the battery device, conforms to the working condition of the battery device, is more accurate, and is conducive to improving the current calibration accuracy.

[0106] See also Figure 7 , Figure 7 This is a flow chart of the current calibration method in some embodiments of the present application. The battery pack BMS performs the following steps:

[0107] S10, the battery pack sends a charging request current to the charging cabinet, receives a target charging current sent by the charging cabinet, and the battery pack collects the actual charging current.

[0108] S20, determining whether the charging request current is less than or equal to a second current threshold.

[0109] If the charging request current is less than or equal to the second current threshold, step S30 is executed; if the charging request current is greater than the second current threshold, step S40 is executed.

[0110] Wherein, step S30 includes the following steps S31 and S32.

[0111] S31, calculating a first absolute value of a difference between a target charging current and an actual charging current.

[0112] If the absolute value of the first difference exceeds the current sampling accuracy of the battery device for a first consecutive number of times, step 32 is executed.

[0113] S32, determining whether the charging request current reaches a third current threshold.

[0114] If the charging request current reaches the third current threshold, step 50 is executed to trigger the current calibration method.

[0115] Wherein, step S40 includes the following steps S41 and S42.

[0116] S41, calculating a first absolute value of a difference between a target charging current and an actual charging current, and a first ratio between the absolute value of the first difference and the target charging current.

[0117] If the first ratio exceeds the first ratio threshold for a second consecutive time, step S42 is executed.

[0118] S42, determining whether the charging request current reaches a third current threshold.

[0119] If the charging request current reaches the third current threshold, step 50 is executed to trigger the current calibration method.

[0120] Step S50 includes the following steps S51 and S52.

[0121] S51, obtaining a plurality of current samples, where the current samples include an actual charging current and a target charging current.

[0122] S52, performing function fitting on the multiple current samples, and defining the obtained function parameters as target charging current calibration coefficients.

[0123] S60, calibrating the actual charging current using the target charging current calibration coefficient to obtain a calibrated charging current.

[0124] S70, determining whether the calibration charging current is less than or equal to a fifth current threshold.

[0125] If the calibration charging current is less than or equal to the fifth current threshold, step S80 is executed; if the calibration charging current is greater than the fifth current threshold, step S90 is executed.

[0126] S80, calculating a second absolute value of a difference between the calibration charging current and the target charging current.

[0127] If the absolute value of the second difference does not exceed the current sampling accuracy of the battery device, step S100 is executed.

[0128] S90, calculating a second absolute value of a difference between the calibration charging current and the target charging current, and a second ratio between the absolute value of the second difference and the target charging current.

[0129] If the second ratio is less than or equal to the second ratio threshold, step S100 is executed.

[0130] S100, using a target charging current calibration coefficient to correct a current charging current calibration coefficient, and storing the target charging current calibration coefficient in a memory.

[0131] In this embodiment, the battery pack BMS monitors the trigger conditions of the current calibration method in two situations: low current charging and high current charging. If the trigger conditions are met, current calibration is performed. After the calibration is completed, the target charging current calibration coefficient is verified in two situations: low current charging and high current charging. After the verification is passed, the target charging current calibration coefficient is used to correct the current charging current calibration coefficient. In this way, the current calibration coefficient is adaptively learned and corrected to maintain a high calibration accuracy, thereby improving the current accuracy and reducing the cost of returning to the factory for repairs due to insufficient accuracy.

[0132] The above describes the current calibration method for charging current. Similarly, for discharge current, a discharge current sample is constructed by combining the target discharge current sent by other devices with the actual discharge current collected by the battery pack. Exemplarily, the other device is a charging cabinet or an electrical device.

[0133] In some embodiments, the charging cabinet includes a power storage module. After the battery pack is electrically and communicatively connected to the charging cabinet, the battery pack first discharges the power storage module with a certain discharge current. The battery pack collects the actual discharge current, and the charging cabinet sends a target discharge current to the battery pack to obtain a discharge current sample.

[0134] The battery pack BMS performs function fitting on multiple discharge current samples and defines the obtained function parameters as the target discharge current calibration coefficients.

[0135] In some embodiments, the target discharge current calibration coefficient is verified, and after verification, the target discharge current calibration coefficient is used to correct the current discharge current calibration coefficient, and the target discharge current calibration coefficient is stored in the memory. In some embodiments, the target discharge current calibration coefficient is verified in two cases: low current discharge and high current discharge.

[0136] In this way, the discharge current calibration coefficient is adaptively learned and corrected to maintain a high calibration accuracy, thereby improving current accuracy and reducing the cost of returning to the factory for repairs due to insufficient accuracy.

[0137] Electrical devices

[0138] Some embodiments of the present application also provide an electrical device, including the battery device in any one of the above embodiments.

[0139] The electrical device of the present application is not particularly limited. In some embodiments, the electrical device may include a battery energy storage system, an electric motorcycle, an electric bicycle, an electric tool, a sweeping robot, an automatic guided vehicle (AGV), an uninterruptible power supply (UPS), etc.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A current calibration method, characterized in that: include: Acquire multiple current samples, each of which includes a target charging current and an actual charging current, define the target charging current as a charging current transmitted by the charging device to the battery device in response to a charging request current sent by the battery device to the charging device, and define the actual charging current as a charging current sampled when the battery device is charged; Based on the plurality of current samples, a target charging current calibration factor is determined.

2. The current calibration method according to claim 1, characterized in that: The charging request current includes: a first charging request current, and increasing in increments with a first step length until a last charging request current is greater than or equal to a first current threshold; The first current threshold is the maximum value of the allowable charging current of the battery device.

3. The current calibration method according to claim 1 or 2, characterized in that: Determining a target charging current calibration coefficient based on the plurality of current samples comprises: Function fitting is performed on the target charging current and the actual charging current to obtain function parameters, and the function parameters are defined as the target charging current calibration coefficients.

4. The current calibration method according to claim 1, characterized in that: include: In response to the charging request current being less than or equal to a second current threshold, calculating a first absolute value of a difference between the target charging current and the actual charging current; In response to the absolute value of the first difference exceeding the current sampling accuracy of the battery device for a first consecutive number of times, triggering the current calibration method; or, In response to the charging request current being greater than the second current threshold, calculating a first absolute value of a difference between the target charging current and the actual charging current, and a first ratio between the absolute value of the first difference and the target charging current; In response to the first ratio exceeding a first ratio threshold a second number of times in a row, the current calibration method is triggered.

5. The current calibration method according to claim 4, characterized in that: In response to the absolute value of the first difference exceeding the current sampling accuracy of the battery device for the first consecutive first time, triggering the current calibration method includes: In response to the absolute value of the first difference exceeding the current sampling accuracy of the battery device for a first consecutive number of times and the charging request current reaching a third current threshold, triggering the current calibration method; The third current threshold is K times the maximum value of the allowable charging current of the battery device, and 0.5≤K≤1; or, In response to the first ratio exceeding a first ratio threshold for a second consecutive number of times, triggering the current calibration method includes: In response to the first ratio exceeding the first ratio threshold for the second number of consecutive times and the charging request current reaching a third current threshold, triggering the current calibration method; The third current threshold is K times the maximum value of the allowable charging current of the battery device, and 0.5≤K≤1.

6. The current calibration method according to any one of claims 1 to 5, characterized in that: include: Calibrate the actual charging current using the target charging current calibration coefficient to obtain a calibrated charging current; In response to the calibration charging current being less than or equal to a fifth current threshold, calculating a second absolute value of a difference between the calibration charging current and the target charging current; In response to the absolute value of the second difference not exceeding the current sampling accuracy of the battery device, correcting the current charging current calibration coefficient using the target charging current calibration coefficient, and storing the target charging current calibration coefficient in a memory; or, In response to the calibration charging current being greater than the fifth current threshold, calculating a second absolute value of a difference between the calibration charging current and the target charging current, and a second ratio between the absolute value of the second difference and the target charging current; In response to the second ratio being less than or equal to a second ratio threshold, the target charging current calibration coefficient is used to correct the current charging current calibration coefficient, and the target charging current calibration coefficient is stored in a memory.

7. The current calibration method according to claim 6, characterized in that: The adopting the target charging current calibration coefficient to correct the current charging current calibration coefficient comprises: In response to the current temperature of the battery device falling into a target temperature interval, the target charging current calibration coefficient is used to correct the current charging current calibration coefficient corresponding to the target temperature interval.

8. A battery management system, characterized in that: It comprises a processor and a memory, wherein the memory is used to store instructions, and the processor is used to execute the instructions to implement the current calibration method according to any one of claims 1 to 7.

9. A battery device, characterized in that: It comprises a battery pack and a battery management system as claimed in claim 8.

10. An electrical device, characterized in that: Comprising a battery device as claimed in claim 9.

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