Charging parameter acquisition method, charging method, electronic equipment and medium

Abstract

The invention provides a charging parameter acquisition method, a charging method, electronic equipment and a medium. The charging parameter acquisition method comprises the following steps: calculating a first polarization internal resistance of the battery at a cell charging temperature according to the received cell charging temperature of the battery and a pre-established temperature-polarization internal resistance model; and calculating a first full charge cut-off voltage of the battery at the charging temperature of the battery cell according to the first polarization internal resistance, a first charging current corresponding to the charging temperature of the battery cell and a pre-established equivalent circuit model of the battery. The battery can be prevented from being overcharged, so that the battery is effectively protected, the operation safety of the battery is ensured, and the service life of the battery is prolonged; it can be guaranteed that the battery has enough capacity when being fully charged, and the accuracy of SOC calculation is guaranteed; furthermore, the charging parameter acquisition method provided by the invention does not need to increase any hardware cost, and is easy to implement.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and in particular to a charging parameter acquisition method, a charging method, an electronic device and a readable storage medium. Background Art

[0002] Lithium-ion batteries are secondary batteries (rechargeable batteries) that rely on the movement of lithium ions between the positive and negative electrodes to work. In lithium-ion batteries, the negative electrode material is a layered structure, and the positive electrode is a pile of angular crystals, the shape of which varies depending on the positive electrode material. During the charge and discharge process, lithium ions are embedded and de-embedded back and forth between the two electrodes.

[0003] Specifically, during the discharge process, lithium ions move from the negative electrode to the positive electrode. In order to ensure that the lithium ions can be smoothly embedded in the carbon layer during the next charge, the lithium ions cannot move completely to the positive electrode during discharge. This is because if the negative electrode layered structure is over-discharged, it will cause the collapse of the negative electrode, thereby limiting the number of lithium ions embedded in the negative electrode carbon layer during recharging, resulting in a decrease in battery capacity, an increase in internal resistance, and even a shortened and irreversible life of the lithium-ion battery.

[0004] During the charging process, lithium ions are deintercalated from the positive electrode and embedded in the negative electrode. However, when some abnormal conditions occur, such as insufficient lithium embedding space in the negative electrode, too much resistance to lithium ion embedding in the negative electrode, or lithium ions are deintercalated from the positive electrode too quickly but cannot be embedded in the negative electrode in equal amounts, the lithium ions that cannot be embedded in the negative electrode can only obtain electrons from the surface of the negative electrode, thereby forming a silvery-white metallic lithium single substance, which is often referred to as "lithium precipitation". After the lithium-ion battery is overcharged, the negative electrode changes from the embedding reaction of lithium ions to the deposition of lithium metal on the surface of the negative electrode. The negative electrode sheet is full of needle-shaped lithium metal crystals, which pierce the diaphragm and cause a short circuit. In mild cases, self-discharge is aggravated; in severe cases, the crystal dendrites short-circuit, the current causes the battery temperature to rise sharply, and the electrolyte decomposes and vaporizes. Once this happens, whether the temperature is too high to cause the material to burn and explode, or the shell is broken first, causing the air entering and the lithium metal to undergo intense oxidation, most of them end in combustion and explosion, posing a huge safety hazard.

[0005] It can be seen that the working mechanism of lithium-ion batteries determines that lithium-ion batteries can neither be overcharged nor over-discharged. This requires that the control of lithium-ion battery charging and discharging must have higher precision to avoid overcharging and over-discharging of lithium batteries, thereby ensuring the safe use of lithium-ion batteries and extending their service life.

[0006] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide a charging parameter acquisition method, a charging method, an electronic device and a readable storage medium. The present invention can not only prevent the battery from being overcharged, thereby effectively protecting the battery and extending the service life of the battery; but also ensure that the battery has sufficient capacity when fully charged, and ensure the accuracy of SOC (State Of Charge) calculation; further, the present invention does not need to increase any hardware cost.

[0008] In order to achieve the above object, the present invention is implemented by the following technical solution: a charging parameter acquisition method for obtaining a full charge cut-off voltage of a battery, the method comprising:

[0009] Calculating a first polarization internal resistance of the battery at the battery cell charging temperature according to the received battery cell charging temperature and a pre-built temperature-polarization internal resistance model;

[0010] A first full-charge cut-off voltage of the battery at the battery cell charging temperature is calculated according to the first polarization internal resistance, the first charging current corresponding to the battery cell charging temperature, and a pre-built equivalent circuit model of the battery.

[0011] Optionally, before calculating the first polarization internal resistance of the battery at the battery cell charging temperature, the charging parameter acquisition method further includes:

[0012] Acquire at least three sets of battery cell model data of the battery, wherein the battery cell model data includes a first battery cell sampling temperature and a corresponding first sampled polarization internal resistance;

[0013] The model parameters of the temperature-polarization internal resistance model are determined according to the exponential law of the variation of the cell reaction rate of the battery with the temperature and the cell model data.

[0014] Optionally, the temperature-polarization internal resistance model includes an Arrhenius equation, and the model parameters include a pre-exponential factor and a ratio of apparent activation energy to a molar gas constant.

[0015] Optionally, before calculating the first polarization internal resistance of the battery at the battery cell charging temperature, the charging parameter acquisition method further includes:

[0016] Determine at least 3 different second battery cell sampling temperatures, and perform a polarization internal resistance test on the battery at each of the second battery cell sampling temperatures using a power test to obtain a second sampled polarization internal resistance of the battery at each of the second battery cell sampling temperatures;

[0017] Polynomial fitting is performed on at least three groups of the second battery cell sampled temperatures and the corresponding second sampled polarization internal resistances, and the temperature-polarization internal resistance model is obtained according to the fitting results.

[0018] Optionally, the power test comprises a HPPC test or a modified HPPC test.

[0019] Optionally, the equivalent circuit model includes a first-order equivalent circuit model of the battery, the first-order equivalent circuit model includes a voltage source, a first resistor and an RC circuit connected in series, the RC circuit includes a second resistor and a capacitor connected in parallel; the voltage of the voltage source is the open circuit voltage of the battery, and the resistance of the second resistor is the polarization internal resistance of the battery; the charging parameter acquisition method includes:

[0020] The resistance value of the first resistor is calculated according to the first open circuit voltage, the second charging current, the second polarization internal resistance and the second full charge cut-off voltage at a preset characteristic temperature;

[0021] A first full-charge cut-off voltage of the battery at the battery cell charging temperature is calculated according to the second open-circuit voltage at the battery cell charging temperature, the first charging current, and the resistance value of the first resistor.

[0022] In order to achieve the above object, the present invention further provides a charging method, the charging method comprising:

[0023] Acquire a current temperature of a cell of the battery to be charged, use the current temperature as the cell charging temperature, and use any of the above charging parameter acquisition methods to calculate a third full-charge cut-off voltage of the battery to be charged at the current charging temperature;

[0024] The battery to be charged is charged according to the current temperature of the battery cell, the third full charge cut-off voltage, and a preset charging strategy of battery cell temperature-SOC full charge cut-off voltage-charging current until the voltage of the battery to be charged reaches the third full charge cut-off voltage.

[0025] In order to achieve the above object, the present invention provides another charging method, which comprises:

[0026] Determine the characteristic charging temperature of the battery to be charged according to the preset charging strategy of battery cell temperature-SOC full charge cut-off voltage-charging current; and for each of the characteristic charging temperatures: use any of the above-mentioned charging parameter acquisition methods to calculate the fourth full charge cut-off voltage corresponding to the characteristic charging temperature, and update the preset charging strategy according to the fourth full charge cut-off voltage;

[0027] Get the current temperature of the battery cell to be charged;

[0028] The battery to be charged is charged according to the current temperature of the battery cell and the updated preset charging strategy until the voltage of the battery to be charged reaches a full charge cut-off voltage corresponding to the current temperature of the battery cell.

[0029] In order to achieve the above-mentioned purpose, the present invention also provides an electronic device, which includes a processor and a memory, and a computer program is stored in the memory. When the computer program is executed by the processor, the charging parameter acquisition method described in any one of the above items or the charging method described in any one of the above items is implemented.

[0030] In order to achieve the above-mentioned purpose, the present invention also provides a readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the charging parameter acquisition method as described in any one of the above items or the charging method as described in any one of the above items is implemented.

[0031] Compared with the prior art, the charging parameter acquisition method, charging method, electronic device and readable storage medium provided by the present invention have the following advantages:

[0032] The charging parameter acquisition method provided by the present invention first determines the polarization internal resistance of the battery cell at the charging temperature according to the received battery cell charging temperature and the pre-built temperature-polarization internal resistance model; then calculates the first polarization internal resistance of the battery according to the battery temperature, and then calculates the first full charge cut-off voltage according to the calculated first polarization internal resistance and the first charging current corresponding to the battery cell charging temperature, and the pre-built equivalent circuit model of the battery. It can be seen that the charging parameter acquisition method provided by the present invention can obtain the corresponding polarization internal resistance according to different charging voltages and then obtain the full charge cut-off voltage, rather than using the same full charge cut-off voltage (or the full charge cut-off voltage is a fixed value) at any temperature. Such a configuration can not only prevent the battery from overcharging and effectively protect the battery, ensure the safe operation of the battery, and thus extend the service life of the battery; but also ensure that the battery has sufficient capacity when it is fully charged, and ensure the accuracy of the SOC (State Of Charge) calculation; further, the charging parameter acquisition method provided by the present invention does not need to increase any hardware cost and is easy to implement.

[0033] Since the charging method, electronic device and readable storage medium provided by the present invention belong to the same inventive concept as the charging parameter acquisition method provided by the present invention, the charging method, electronic device and readable storage medium provided by the present invention at least have all the advantages of the charging parameter acquisition method provided by the present invention. For details of the beneficial effects of the charging method, electronic device and readable storage medium provided by the present invention, please refer to the relevant description of the beneficial effects of the charging parameter acquisition method provided by the present invention in this document, and no further details will be given here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the overall flow of the charging parameter acquisition method provided by the present invention;

[0035] Figure 2 A schematic diagram of a specific flow chart of step S100 of the charging parameter acquisition method provided in the first embodiment of the present invention;

[0036] Figure 3 A schematic diagram of an equivalent circuit model of a battery in the charging parameter acquisition method provided in Embodiment 1 of the present invention;

[0037] Figure 4 A schematic diagram of a specific flow chart of step S100 of the charging parameter acquisition method provided in the second embodiment of the invention;

[0038] Figure 5 A schematic diagram of the corresponding relationship between the polarization internal resistance and the charging temperature of the battery cell in the method for obtaining charging parameters provided in the second embodiment of the present invention;

[0039] Figure 6 A schematic diagram of a charging method according to a third embodiment of the present invention;

[0040] Figure 7 A schematic diagram of a charging method according to a fourth embodiment of the present invention;

[0041] Figure 8 A schematic diagram of the block structure of an electronic device provided in Embodiment 5 of the present invention;

[0042] The reference numerals are as follows:

[0043] Voltage source-OCV, first resistor-R1, second resistor-R2, capacitor-C;

[0044] Processor 110 , memory 120 , communication interface 130 , communication bus 140 . DETAILED DESCRIPTION

[0045] The following is a further detailed description of the charging parameter acquisition method, charging method, electronic device and readable storage medium proposed in the present invention in conjunction with the accompanying drawings. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and all use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Any modification of the structure, change in the proportional relationship or adjustment of the size, in the case of the same or similar effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific environment to be applied and used. And, in the embodiments described below, sometimes the same figure mark is used in common between different drawings to represent the same part or part with the same function, and its repeated description is omitted. In this specification, similar reference numerals and letters are used to refer to similar items, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures. In addition, if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method.

[0046] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements. The singular forms "a", "an" and "the" include plural objects, the term "or" is generally used in a sense including "and / or", the term "several" is generally used in a sense including "at least one", and the term "at least two" is generally used in a sense including "two or more". In addition, the terms "first", "second" and "third" are used for descriptive purposes only and are not to be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features.

[0047] It should be noted that the charging parameter acquisition method, charging method and readable storage medium provided by the present invention can be applied to the electronic device provided by the present invention, and the charging parameter acquisition method, charging method, electronic device and readable storage medium provided by the present invention can be applied to vehicles. It should be understood that the term "vehicle" or "vehicle" or other similar terms used herein include general motor vehicles, such as passenger vehicles including sports utility vehicles (SUVs), buses, trucks, various commercial vehicles, and hybrid vehicles, electric vehicles, and plug-in hybrid electric vehicles.

[0048] The core idea of ​​the present invention is to provide a charging parameter acquisition method, a charging method, an electronic device and a readable storage medium. The present invention can not only prevent the battery from overcharging, thereby effectively protecting the battery and extending the service life of the battery; but also ensure that the battery has sufficient capacity when fully charged, thereby ensuring the accuracy of SOC calculation; further, the present invention does not need to increase any hardware cost and is easy to implement.

[0049] In order to make it easier to understand and explain the present invention, the research process of proposing the present invention is briefly described below, and then the present invention is generally explained in general. Finally, the specific embodiments of the electrical parameter acquisition method, charging method, electronic device and readable storage medium proposed in the invention are described in detail.

[0050] As described in the background technology, the working mechanism of lithium-ion batteries determines that lithium-ion batteries cannot be overcharged or over-discharged, and requires that the control of charging and discharging of lithium-ion batteries must have high precision. In order to meet this requirement, the current battery management system (BMS) basically adopts the charging strategy of cell temperature-SOC full charge cut-off voltage-charging current provided by the cell manufacturer and adopts a fixed charging current, that is, the charging request current is determined by looking up the table according to the cell temperature and SOC (or cell voltage) corresponding to the battery to be charged. For example, as shown in Table 1 below, a schematic table of the corresponding relationship between the cell temperature-SOC full charge cut-off voltage-charging current of a certain battery is given, where the unit of the current in Table 1 is ampere (A).

[0051] Table 1: Charging current table of a battery cell

[0052]

[0053]

[0054] In view of the fact that the damage to the battery cell is minimal near normal temperature, the charging current table provided by the general battery cell manufacturers is roughly as shown in Table 1. It can be seen from Table 1 that: when the battery cell temperature is lower than a certain temperature threshold (such as -20℃ in Table 1) or higher than a certain temperature threshold (such as 55℃ in Table 1), the charging current is 0, that is, charging is not allowed; within the temperature range that can be charged (such as -19℃ to 50℃), the charging current is smaller at higher or lower temperatures; when the battery cell temperature is near normal temperature, the charging current is the largest. And as the SOC increases, the charging current gradually decreases.

[0055] However, research has found that in the relevant technology, the charging request current determined by the charging strategy based on the cell temperature-SOC full charge cut-off voltage-charging current provided by the cell manufacturer does not take into account the polarization phenomenon of the cell at different temperatures. This method has the following defects: if the same full charge cut-off voltage is used when charging at different temperatures, the cell is prone to overcharge and lithium deposition at high temperatures; or if the actual output current of the charging pile is less than the BMS charging request current, the cell polarization becomes weak, which may cause overcharging, resulting in a sharp increase in battery temperature, electrolyte vaporization, and even combustion and explosion, endangering life and property safety.

[0056] Based on the above research, the present invention provides a charging parameter acquisition method for obtaining the full charge cut-off voltage of a battery. For example, see Figure 1 , Figure 1 The overall flow chart of the charging parameter acquisition method provided by the present invention is as follows: Figure 1 It can be seen that the charging parameter acquisition method includes:

[0057] S100: calculating a first polarization internal resistance of the battery at the battery cell charging temperature according to the received battery cell charging temperature and a pre-built temperature-polarization internal resistance model;

[0058] S200: Calculate a first full-charge cut-off voltage of the battery at the battery cell charging temperature according to the first polarization internal resistance and a first charging current corresponding to the battery cell charging temperature, and a pre-built equivalent circuit model of the battery.

[0059] The charging parameter acquisition method provided by the present invention first determines the polarization internal resistance at the charging temperature of the battery cell according to the received charging temperature of the battery cell and the pre-built temperature-polarization internal resistance model; then calculates the first polarization internal resistance of the battery according to the battery temperature, and then calculates the first full charge cut-off voltage according to the calculated first polarization internal resistance and the first charging current corresponding to the charging temperature of the battery cell, and the pre-built equivalent circuit model of the battery. It can be seen that the charging parameter acquisition method provided by the present invention can obtain the corresponding polarization internal resistance according to different charging voltages and then obtain the full charge cut-off voltage, rather than using the same full charge cut-off voltage at any temperature (that is, the full charge cut-off voltage is a fixed value). Such a configuration can not only prevent the battery from overcharging and effectively protect the battery, ensure the safe operation of the battery, and thus extend the service life of the battery; but also ensure that the battery has sufficient capacity when it is fully charged, and ensure the accuracy of the SOC (State Of Charge) calculation; further, the charging parameter acquisition method provided by the present invention does not need to increase any hardware cost and is easy to implement.

[0060] Specifically, taking lithium-ion batteries as an example, as mentioned above, the battery charging process is mainly the release process of lithium ions, and the influence of polarization needs to be considered to achieve precise control of battery charging and avoid overcharging of the battery. Therefore, assuming that the reaction of this process is determined by kinetics rather than thermodynamics, the polarization internal resistance of the battery is According to the Arrhenius formula:

[0061] k=Aexp(-E a / RT) (1)

[0062] Transform formula (1) to obtain:

[0063]

[0064] In the above formulas (1) and (2), k is the rate constant, A is the pre-exponential factor (also called frequency factor), and E a is the apparent activation energy, R is the molar gas constant, T is the thermodynamic temperature (when the battery is charged, it is the cell charging temperature), R ctis the polarization internal resistance. Based on the fact that the thermodynamic temperature change is not particularly large, E a The fact that the polarization internal resistance R ct It is nonlinearly inversely proportional to the temperature T. In other words, the polarization internal resistance of the battery is inconsistent at different charging temperatures, so even if the charging request current remains unchanged, the same full charge cut-off voltage cannot be used.

[0065] It should be noted that, as those skilled in the art can understand, the above-mentioned charging parameter acquisition method provided by the present invention is only an exemplary description of a preferred embodiment using a lithium-ion battery as an example, and is not a limitation of the present invention. The charging parameter acquisition method provided by the present invention does not impose too many restrictions on the battery cell material of the battery. For example, the battery can be, but is not limited to, a lithium iron phosphate battery, a lithium manganese oxide battery, a ternary polymer lithium battery, and a lithium cobalt oxide battery, etc. They are not listed one by one here.

[0066] It should be noted that the present invention does not impose too many restrictions on the specific construction method of the temperature-polarization internal resistance model in step S100. Similarly, the equivalent circuit model of the battery in step S200 is not limited too much. The equivalent circuit model can be, but is not limited to, a first-order equivalent circuit model and a second-order equivalent circuit model. Next, the charging parameter acquisition method provided by the present invention is exemplarily described by taking Example 1 and Example 2 as examples.

[0067] Embodiment 1

[0068] The charging parameter acquisition method provided in this embodiment, before calculating the first polarization internal resistance of the battery at the battery cell charging temperature in step S100, the charging parameter acquisition method further includes building a temperature-polarization internal resistance model. In this embodiment, building the temperature-polarization internal resistance model specifically includes the following steps:

[0069] S111: Acquire at least three groups of battery cell model data of the battery, wherein the battery cell model data includes a first battery cell sampled temperature and a corresponding first sampled polarization internal resistance.

[0070] S112: Determine model parameters of the temperature-polarization internal resistance model according to the exponential law of how the reaction rate of the battery cell changes with temperature and the battery cell model data.

[0071] Therefore, the charging parameter acquisition method provided by the present invention determines the model parameters of the temperature-polarization internal resistance model according to the exponential law of the change of the battery cell reaction rate with the temperature obtained by at least 3 groups of battery cell model data and the battery cell reaction rate. It fully combines the law of the change of the battery cell reaction rate with the temperature and has high accuracy; the logic is simple and easy to implement.

[0072] Preferably, the temperature-polarization internal resistance model includes the Arrhenius formula, and the model parameters include the pre-exponential factor and the ratio of the apparent activation energy to the molar gas constant. Due to space limitations, this article does not elaborate on the principles and applications of the Arrhenius formula. For details of the Arrhenius formula, please refer to the relevant technologies known to those skilled in the art.

[0073] For example, see Figure 2 , Figure 2 The specific flow chart of step S100 of the charging parameter acquisition method provided in this embodiment. Figure 2 It can be seen that, in this example, the specific steps of obtaining the first polarization internal resistance include:

[0074] SA1: Acquire cell model data of the battery at at least three first cell sampling temperatures (ie, the first cell sampling temperature and the corresponding first sampled polarization internal resistance).

[0075] It should be noted that the present invention does not impose too many restrictions on the specific acquisition method of the first battery cell sampling temperature and the corresponding first sampled polarization internal resistance. For example, the first battery cell sampling temperature can be measured by a thermometer; the first sampled polarization internal resistance can be calculated according to Ohm's law. Furthermore, the present invention does not impose too many restrictions on the specific value of the first battery cell sampling temperature. For example, it can be selected within the temperature range where the battery can be charged based on 25°C.

[0076] SA2: Calculate the ratio of the apparent activation energy to the molar gas constant and the pre-exponential factor based on the Arrhenius equation.

[0077] Specifically, according to the above formula (1), taking 25°C as the benchmark, the three cell model data can be used to calculate two unknown quantities: the ratio of the apparent activation energy to the molar gas constant - E a / R and pre-exponential factor A, determine the temperature-polarization internal resistance model based on the Arrhenius formula.

[0078] SA3: Calculate the first polarization internal resistance according to the battery cell charging temperature and the temperature-polarization internal resistance model (ie, the Arrhenius formula).

[0079] Specifically, the charging temperature of the battery cell and the ratio of the apparent activation energy to the molar gas constant calculated in step SA2 are calculated as follows: a Substituting / R and the pre-exponential factor A into formula (2), the first polarization internal resistance can be obtained.

[0080] Further, in some exemplary embodiments, the equivalent circuit model in step S200 includes a first-order equivalent circuit model of the battery. Figure 3 , Figure 3 Schematic diagram of an equivalent circuit model of a battery in the charging parameter acquisition method provided in this embodiment. Figure 3 It can be seen that the first-order equivalent circuit model includes a voltage source OCV, a first resistor R1 and an RC circuit (not shown in the figure) connected in series, and the RC circuit includes a second resistor R2 and a capacitor C connected in parallel; the voltage of the voltage source OCV is the open circuit voltage U of the battery ocv The resistance of the second resistor R2 is the polarization internal resistance R of the battery. ct ; The charging parameter acquisition method comprises:

[0081] S210: Calculate the resistance value of the first resistor R1 according to the first open circuit voltage, the second charging current, the second polarization internal resistance and the second full charge cut-off voltage at a preset characteristic temperature.

[0082] Specifically, according to relevant research, the resistance value of the first resistor R1 is R o Independent of charging temperature. For example, Figure 2 According to Ohm's law, the R of the first resistor R1 can be obtained by the following formula (3): o :

[0083] U ocv +I×(R o +R ct )=U (3)

[0084] In formula (3), U ocv is the open circuit voltage, I is the charging current, R o is the resistance value of the first resistor R1, R ct is the polarization internal resistance of the battery, and U is the full charge cut-off voltage.

[0085] Assume that in a certain example, the preset characteristic temperature is 25°C, and the open circuit voltage U of the battery at 25°C is known to be ocv_25 , charging current I 25 , polarization internal resistance R ct_25 , full charge cut-off voltage U 25 , then R can be calculated o .

[0086] It should be noted that the present invention does not impose too many restrictions on the specific value of the preset characteristic temperature. Preferably, the preset characteristic temperature is preferably a temperature near normal temperature in the charging strategy of battery cell temperature-SOC full charge cut-off voltage-charging current (for example, Table 1 above) provided by the battery cell manufacturer, such as 20°C, 30°C, etc.

[0087] S220: Calculate a first full-charge cut-off voltage of the battery at the battery cell charging temperature according to the second open-circuit voltage at the battery cell charging temperature, the first charging current, and the resistance value of the first resistor R1.

[0088] Specifically, the first full charge cut-off voltage of the battery when the battery cell charging temperature is T can be calculated by the following formula (4):

[0089]

[0090] In formula (4), U T is the first full charge cut-off voltage at the battery cell charging temperature T, U ocv_T The open circuit voltage of the battery cell at the charging temperature (i.e., the second open circuit voltage in this article), I T is the first charging current at the charging temperature T of the battery cell. According to the description of step S210, it can be known that:

[0091] is the resistance value of the first resistor R1 o .

[0092] Specifically, U 25 , U ocv_25 ,I 25 and R ct_25 They are respectively the full charge cut-off voltage, open circuit voltage, charging current and polarization internal resistance when the cell charging temperature is 25°C.

[0093] Further studies have shown that at different cell charging temperatures T, after the battery is fully stationary, the same SOC value, open circuit voltage U T The open circuit voltage U at 25°C ocv_25 When the battery cell charging temperature T>25℃, the charging current I T The charging current I at 25°C 25 If they are equal, then U T <U 25 , that is, if the charging current is consistent, when the temperature is higher, then in order to protect the battery, the full charge cut-off voltage should be lower. It can be seen that the charging parameter acquisition method provided by the present invention can prevent the battery from being overcharged and thus effectively protect the battery.

[0094] Embodiment 2

[0095] The charging parameter acquisition method provided in this embodiment has basically the same principle as the charging parameter acquisition method provided in Embodiment 1. To avoid redundancy, only the differences from Embodiment 1 are described below. For parts not mentioned in this embodiment, please refer to the relevant description of Embodiment 1 for adaptive understanding.

[0096] Specifically, the charging parameter acquisition method provided in this embodiment is different from that in the first embodiment in the way of constructing the temperature-polarization internal resistance model. Exemplarily, the charging parameter acquisition method provided in this embodiment, before calculating the first polarization internal resistance of the battery at the battery cell charging temperature, further includes:

[0097] S121: determining at least three different second battery cell sampling temperatures, and performing a polarization internal resistance test on the battery at each of the second battery cell sampling temperatures by using a power test to obtain a second sampled polarization internal resistance of the battery at each of the second battery cell sampling temperatures;

[0098] S122: Perform polynomial fitting on at least three groups of the second battery cell sampled temperatures and the corresponding second sampled polarization internal resistances, and obtain the temperature-polarization internal resistance model according to the fitting results.

[0099] Therefore, the charging parameter acquisition method provided by the present invention, which determines the model parameters of the temperature-polarization internal resistance model by fitting the measured data, is not only highly reliable but also simple in logic and easy to implement.

[0100] Preferably, the power test includes a HPPC (Hybrid Plus Power Characterization) test or an improved HPPC test. Due to space limitations, this article does not elaborate on the HPPC test or the improved HPPC test. For details of the HPPC test or the improved HPPC test, please refer to the relevant technologies known to those skilled in the art.

[0101] It is clear that the present invention does not impose too many restrictions on the specific value of the second battery cell sampling temperature. For example, it can be selected within the temperature range where the battery can be charged, based on 25°C. Further, the present invention does not impose too many restrictions on the polynomial fitting method. For example, the polynomial fitting method can be, but is not limited to, the least squares method, the Grange interpolation method, and the Newton interpolation method.

[0102] For example, see Figure 4 , Figure 4 This is a schematic diagram of a specific flow chart of step S100 of the charging parameter acquisition method provided in the second embodiment of the invention. Figure 4 It can be seen that, in this example, the specific steps of obtaining the first polarization internal resistance include:

[0103] SB1: Perform an HPPC test to obtain at least three second battery cell sampling temperatures and the corresponding second sampled polarization internal resistances.

[0104] SB2: Perform minimum multiplication fitting on at least three second battery cell sample temperatures and the corresponding second sample polarization internal resistances to construct the temperature-polarization internal resistance model (temperature-polarization internal resistance function relationship).

[0105] For example, see Figure 5 , Figure 5 A schematic diagram of the corresponding relationship between the polarization internal resistance and the charging temperature of the battery cell in the charging parameter acquisition method provided by this embodiment. Figure 5 It can be seen that there is a good nonlinear relationship between the polarization internal resistance and the battery cell charging temperature.

[0106] Specifically, Figure 5 The polarization internal resistance and the cell charging temperature shown in are shown in the following formula (5):

[0107] R ct_T =0.0002T 2 -0.014T+0.5 (5)

[0108] In formula (5), R ct_T It is the polarization internal resistance corresponding to the battery cell charging temperature T, where T is the battery cell charging temperature.

[0109] It should be understood that formula (5) is only an exemplary explanation and not a limitation of the present invention. The order and number of terms of the functional relationship between the polarization internal resistance and the charging temperature of the battery cell are determined by the characteristics of the battery and the fitting method.

[0110] SB3: Calculate the first polarization internal resistance according to the battery cell charging temperature and the temperature-polarization internal resistance model (ie, the fitted temperature-polarization internal resistance function relationship).

[0111] Embodiment 3

[0112] Based on the same inventive concept, this embodiment provides a charging method. Figure 6 , Figure 6 The figure is a flow chart of the charging method provided by the present invention. Figure 6 It can be seen that the charging method provided in this embodiment includes the following steps:

[0113] S311: Acquire the current temperature of the battery cell to be charged, use the current temperature as the battery cell charging temperature, and use the charging parameter acquisition method provided in any of the above embodiments to calculate the third full charge cut-off voltage of the battery to be charged at the current charging temperature.

[0114] S312: charging the battery to be charged according to the current temperature of the battery cell, the third full charge cut-off voltage, and a preset charging strategy of battery cell temperature-SOC full charge cut-off voltage-charging current, until the voltage of the battery to be charged reaches the third full charge cut-off voltage.

[0115] It can be seen that in the charging method provided by the present invention, the full charge cut-off voltage is obtained according to the current charging temperature, and the battery to be charged is charged according to the current temperature of the battery cell, the third full charge cut-off voltage and the preset charging strategy of the battery cell temperature-SOC full charge cut-off voltage-charging current. Therefore, it can prevent the battery from overcharging and effectively protect the battery, ensure the safe operation of the battery, and thus extend the service life of the battery.

[0116] It should be noted that, as those skilled in the art can understand, the present invention does not impose too many restrictions on the method of obtaining the preset charging strategy of battery cell temperature-SOC full charge cut-off voltage-charging current. Under normal circumstances, as shown in Table 1 above, the preset charging strategy of battery cell temperature-SOC full charge cut-off voltage-charging current is usually provided by the battery manufacturer, which is not elaborated in this article.

[0117] Embodiment 4

[0118] Based on the same inventive concept, this embodiment provides another charging method. Figure 7 , Figure 7 The figure is a flow chart of the charging method provided by the present invention. Figure 7 It can be seen that the charging method provided in this embodiment includes the following steps:

[0119] S321: Determine the characteristic charging temperature of the battery to be charged according to the preset charging strategy of battery cell temperature-SOC full-charge cut-off voltage-charging current; and for each of the characteristic charging temperatures: adopt the charging parameter acquisition method provided in any of the above embodiments to calculate the fourth full-charge cut-off voltage corresponding to the characteristic charging temperature, and update the preset charging strategy according to the fourth full-charge cut-off voltage.

[0120] Specifically, the characteristic charging temperature is a typical cell charging temperature given in a preset charging strategy. Taking Table 1 as an example, the characteristic charging temperatures in Table 1 are -19°C, -15°C, 0°C, 10°C, 30°C, 40°C, 45°C and 50°C respectively.

[0121] S322: Obtain the current temperature of the battery cell to be charged.

[0122] S323: charging the battery to be charged according to the current temperature of the battery cell and the updated preset charging strategy until the voltage of the battery to be charged reaches a full charge cut-off voltage corresponding to the current temperature of the battery cell.

[0123] Therefore, the charging method provided by the present invention first updates the full charge cut-off voltage (i.e., the fourth full charge cut-off voltage) at each characteristic charging temperature according to the characteristic charging temperature of the preset charging strategy of battery cell temperature-SOC full charge cut-off voltage-charging current, and then charges the battery to be charged according to the current temperature of the battery cell and the updated preset charging strategy. Therefore, the charging method provided by the present invention can not only prevent the battery from overcharging, thereby effectively protecting the battery, ensuring the safe operation of the battery, and thereby extending the service life of the battery; and it only needs to update the preset charging strategy once, and the updated preset charging strategy can be used for subsequent charging, and the logic is simpler.

[0124] It should be noted that those skilled in the art should be able to understand that the above step S321 can be performed only once, and the updated preset charging strategy can be used in subsequent charging. For example, please refer to Table 2, which is a cell charging current table of a battery after the full charge cut-off voltage is updated based on Table 1 according to the charging parameter acquisition method provided by the present invention.

[0125] Table 2: Charging current table of a battery cell after an update

[0126]

[0127]

[0128] Specifically, in the last column corresponding to each characteristic charging temperature in Table 2, the data in the upper row is the full charge cut-off voltage, and the data in the lower row is the charging current. Taking 30°C as an example, the full charge cut-off voltage is 3.646V, and the charging current is 0A when fully charged.

[0129] By comparing Table 1 and Table 2, it can be found that in Table 1, regardless of whether the battery cell charging temperature is -19°C, -15°C, ..., or 40°C, 45°C, or 50°C, the full charge cut-off voltage is 3.65V. In Table 2, the corresponding full charge cut-off voltage may be different for different battery cell charging temperatures. For example, when the battery cell charging temperature is 10°C, the corresponding full charge cut-off voltage is 3.65V, and when the battery cell charging temperature is 40°C, the corresponding full charge cut-off voltage is 3.642V. Specifically, in Table 2, when the final terminal charging current is consistent, as the battery cell temperature increases, the full charge cut-off voltage decreases; when the temperature decreases, due to the change in the terminal charging current, the full charge cut-off voltage may remain unchanged or may increase further.

[0130] It should be noted that, as those skilled in the art can understand, the characteristic charging temperature, the SOC value corresponding to each charging stage, the corresponding relationship of the charging current, and the specific value of the full charge cut-off voltage in Table 1 and Table 2 are only exemplary descriptions, and are not limitations of the present invention. Generally, except for the full charge cut-off voltage in Table 2, the other contents in Table 1 and Table 2 have been determined when the battery leaves the factory, and can be obtained from the battery factory parameters provided by the battery manufacturer. This article will not go into details.

[0131] Embodiment 5

[0132] Based on the same inventive concept, this embodiment provides an electronic device, for example, see Figure 8 , Figure 8 Schematic diagram of the block structure of the electronic device provided in this embodiment. Figure 8 As shown, the electronic device includes a processor 110 and a memory 120, and a computer program is stored on the memory 120. When the computer program is executed by the processor 110, the charging parameter acquisition method or the charging method described above can be implemented. Since the electronic device provided by the present invention and the charging parameter acquisition method or the charging method provided by the present invention belong to the same inventive concept, and the charging method provided by the present invention and the charging parameter acquisition method provided by the present invention belong to the same inventive concept, the electronic device provided by the present invention at least has all the advantages of the charging parameter acquisition method provided by the present invention. For details of the beneficial effects of the electronic device provided by the present invention, please refer to the above description of the beneficial effects of the charging parameter acquisition method provided by the present invention, which will not be repeated here.

[0133] For example, Figure 8 As shown, the electronic device may also include a communication interface 130 and a communication bus 140, wherein the processor 110, the communication interface 130, and the memory 120 communicate with each other through the communication bus 140. The communication bus 140 includes but is not limited to a CAN bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus. The communication interface 130 is used for communication between the above-mentioned electronic device (such as a battery management controller) and other controllers (such as a motor controller, a vehicle controller, an automatic driving domain controller, etc., not shown in the figure). The communication bus 140 connects the above-mentioned electronic device (such as a battery management controller) and other controllers (such as a motor controller, etc., not shown in the figure) and other dispersed nodes into a closed-loop system, so that each controller can perform multiple working states (parking state, charging state, starting state, running state, vehicle forward and backward state, feedback braking state, mechanical braking state, general fault state, major fault state) Communication and data transmission, thereby realizing the control function of the vehicle.

[0134] The processor 110 referred to in the present invention may be a microcontroller unit (MCU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc. The processor 110 is the control center of the electronic device, and uses various interfaces and lines to connect various parts of the entire electronic device.

[0135] The memory 120 may be used to store the computer program. The processor 110 implements various functions of the electronic device by running or executing the computer program stored in the memory 120 and calling the data stored in the memory 120 .

[0136] The memory 120 may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0137] Embodiment 6

[0138] Based on the same inventive concept, this embodiment provides a readable storage medium, wherein a computer program is stored in the readable storage medium, and when the computer program is executed by the processor, the charging parameter acquisition method or the charging method described above can be implemented. Since the readable storage medium provided by the present invention and the charging parameter acquisition method or the charging method provided by the present invention belong to the same inventive concept, and the charging method provided by the present invention and the charging parameter acquisition method provided by the present invention belong to the same inventive concept, the readable storage medium provided by the present invention at least has all the advantages of the charging parameter acquisition method provided by the present invention. For details of the beneficial effects of the readable storage medium provided by the present invention, please refer to the above description of the beneficial effects of the charging parameter acquisition method provided by the present invention, which will not be repeated here.

[0139] The readable storage medium of the embodiment of the present invention can adopt any combination of one or more computer-readable media. The readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, a system, device or component of electricity, magnetism, light, electromagnetic, infrared or semiconductor, or any combination of the above. More specific examples (non-exhaustive examples) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer hard disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this article, a computer-readable storage medium can be any tangible medium containing or storing a program, which can be used by an instruction execution system, device or device or used in combination with it.

[0140] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, which carry computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0141] Further, computer program code for performing the operations of the present invention may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" language or similar programming languages.

[0142] Compared with the prior art, the charging parameter acquisition method, charging method, electronic device and readable storage medium provided by the present invention have the following advantages:

[0143] The charging parameter acquisition method provided by the present invention first determines the polarization internal resistance at the charging temperature of the battery cell according to the received battery cell charging temperature and the pre-built temperature-polarization internal resistance model; then the first polarization internal resistance of the battery is calculated according to the battery temperature, and then the first full charge cut-off voltage (i.e., full charge cut-off voltage) is calculated according to the calculated first polarization internal resistance and the first charging current corresponding to the battery cell charging temperature, and the pre-built equivalent circuit model of the battery. It can be seen that the charging parameter acquisition method provided by the present invention can obtain the corresponding polarization internal resistance according to different charging voltages and then obtain the full charge cut-off voltage, rather than using the same full charge cut-off voltage (or the full charge cut-off voltage is a fixed value) at any temperature. Such a configuration can not only prevent the battery from overcharging and effectively protect the battery, ensure the safe operation of the battery, and thus extend the service life of the battery; but also ensure that the battery has sufficient capacity when it is fully charged, and ensure the accuracy of the SOC (State Of Charge) calculation; further, the charging parameter acquisition method provided by the present invention does not need to increase any hardware cost and is easy to implement.

[0144] Since the charging method, electronic device and readable storage medium provided by the present invention belong to the same inventive concept as the charging parameter acquisition method provided by the present invention, the charging method, electronic device and readable storage medium provided by the present invention at least have all the advantages of the charging parameter acquisition method provided by the present invention. For details of the beneficial effects of the charging method, electronic device and readable storage medium provided by the present invention, please refer to the relevant description of the beneficial effects of the charging parameter acquisition method provided by the present invention in this document, and no further details will be given here.

[0145] It should be noted that the devices and methods disclosed in the embodiments of this article can also be implemented in other ways. The device implementation described above is only schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of this article. In this regard, each box in the flowchart or block diagram can represent a part of a module, program or code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented by a dedicated hardware-based system for performing a specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0146] In addition, the functional modules in the various embodiments of this document may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0147] The above description is only a description of a preferred embodiment of a charging parameter acquisition method, a charging method, an electronic device, and a readable storage medium provided by the present invention, and is not any limitation on the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosures are within the scope of protection of the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations fall within the scope of the present invention and its equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A charging parameter acquisition method, characterized in that: For obtaining the full charge cut-off voltage of a battery, the method comprises: Calculating a first polarization internal resistance of the battery at the battery cell charging temperature according to the received battery cell charging temperature and a pre-built temperature-polarization internal resistance model; A first full-charge cut-off voltage of the battery at the battery cell charging temperature is calculated according to the first polarization internal resistance, the first charging current corresponding to the battery cell charging temperature, and a pre-built equivalent circuit model of the battery.

2. The charging parameter acquisition method according to claim 1, characterized in that: Before calculating the first polarization internal resistance of the battery at the battery cell charging temperature, the charging parameter acquisition method further includes: Acquire at least three sets of battery cell model data of the battery, wherein the battery cell model data includes a first battery cell sampling temperature and a corresponding first sampled polarization internal resistance; The model parameters of the temperature-polarization internal resistance model are determined according to the exponential law of the variation of the cell reaction rate of the battery with the temperature and the cell model data.

3. The charging parameter acquisition method according to claim 2, characterized in that: The temperature-polarization internal resistance model includes the Arrhenius formula, and the model parameters include the pre-exponential factor and the ratio of the apparent activation energy to the molar gas constant.

4. The charging parameter acquisition method according to claim 1, characterized in that: Before calculating the first polarization internal resistance of the battery at the battery cell charging temperature, the charging parameter acquisition method further includes: Determine at least 3 different second battery cell sampling temperatures, and perform a polarization internal resistance test on the battery at each of the second battery cell sampling temperatures using a power test to obtain a second sampled polarization internal resistance of the battery at each of the second battery cell sampling temperatures; Polynomial fitting is performed on at least three groups of the second battery cell sampled temperatures and the corresponding second sampled polarization internal resistances, and the temperature-polarization internal resistance model is obtained according to the fitting results.

5. The charging parameter acquisition method according to claim 4, characterized in that: The power test includes a HPPC test or a modified HPPC test.

6. The charging parameter acquisition method according to claim 1, characterized in that: The equivalent circuit model includes a first-order equivalent circuit model of the battery, the first-order equivalent circuit model includes a voltage source, a first resistor and an RC circuit connected in series, the RC circuit includes a second resistor and a capacitor connected in parallel; the voltage of the voltage source is the open circuit voltage of the battery, and the resistance of the second resistor is the polarization internal resistance of the battery; The charging parameter acquisition method comprises: The resistance value of the first resistor is calculated according to the first open circuit voltage, the second charging current, the second polarization internal resistance and the second full charge cut-off voltage at a preset characteristic temperature; A first full-charge cut-off voltage of the battery at the battery cell charging temperature is calculated according to the second open-circuit voltage at the battery cell charging temperature, the first charging current, and the resistance value of the first resistor.

7. A charging method, characterized in that: include: Acquire a current temperature of a battery cell of the battery to be charged, use the current temperature as the battery cell charging temperature, and use the charging parameter acquisition method according to any one of claims 1 to 6 to calculate a third full-charge cut-off voltage of the battery to be charged at the current charging temperature; The battery to be charged is charged according to the current temperature of the battery cell, the third full charge cut-off voltage, and a preset charging strategy of battery cell temperature-SOC full charge cut-off voltage-charging current until the voltage of the battery to be charged reaches the third full charge cut-off voltage.

8. A charging method, characterized in that: include: Determine the characteristic charging temperature of the battery to be charged according to the preset charging strategy of battery cell temperature-SOC full charge cut-off voltage-charging current; And for each of the characteristic charging temperatures: using the charging parameter acquisition method according to any one of claims 1 to 6, calculating a fourth full charge cut-off voltage corresponding to the characteristic charging temperature, and updating the preset charging strategy according to the fourth full charge cut-off voltage; Get the current temperature of the battery cell to be charged; The battery to be charged is charged according to the current temperature of the battery cell and the updated preset charging strategy until the voltage of the battery to be charged reaches a full charge cut-off voltage corresponding to the current temperature of the battery cell.

9. An electronic device, characterized in that: The electronic device includes a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the charging parameter acquisition method according to any one of claims 1 to 6 or the charging method according to any one of claims 7 to 8 is implemented.

10. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and when the computer program is executed by a processor, the charging parameter acquisition method according to any one of claims 1 to 6 or the charging method according to any one of claims 7 to 8 is implemented.

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