Battery charge state calibration method and system, vehicle-mounted terminal and storage medium

Abstract

The invention provides a battery state-of-charge calibration method and system, a vehicle-mounted terminal and a storage medium, and the method comprises the steps: obtaining battery parameters which comprise a state parameter and a first change relation of voltage along with time under a preset discharge current after pulse heating, the state parameters comprise a health state, a first charge state before pulse heating and a temperature after pulse heating; matching a first characteristic parameter of the battery from a battery characteristic matrix according to the state parameter; fitting is carried out according to the first characteristic parameter and the discharge current, and a second change relation of the voltage along with time is determined; and calibrating the first charge state according to a first deviation between the second change relation and the first change relation, and determining a second charge state after pulse heating. According to the method, the battery characteristic parameters and the charge state are mapped according to the deviation between the theoretical voltage response and the actual voltage response after the pulse heating, the charge state calibration after the pulse heating of the battery is realized, and the accuracy of charge state estimation is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery state of charge calibration method, system, vehicle-mounted terminal and storage medium. Background Art

[0002] With the increasing global awareness of environmental protection and the growing demand for renewable energy, new energy vehicles have received widespread attention and development due to their low-carbon and environmentally friendly characteristics, including extended-range electric vehicles, plug-in hybrid electric vehicles (PHEVs) and pure electric vehicles. In new energy vehicles, the power battery is one of the core components, and its performance directly affects the power, economy and safety of the entire vehicle. Therefore, accurately estimating the battery's SOC (State of Charge) is crucial for the normal operation of the vehicle. However, in low-temperature environments, the performance of the battery will significantly decrease. In order to overcome this problem, many new energy vehicles use pulse heating technology, that is, by applying high-frequency pulse current to the battery, heat is generated inside the battery, thereby rapidly raising the battery's temperature and improving its low-temperature performance. However, because the battery's temperature, internal resistance, voltage and other parameters will change during the pulse heating process, this poses new challenges to the estimation of SOC.

[0003] In the related art, one of the commonly used SOC estimation methods is the ampere-hour integration method, which calculates the change in battery charge by real-time monitoring of the battery's charge and discharge current and performing integration operations on it. However, in actual applications, when the battery uses pulse heating technology to improve performance under low temperature conditions, the high-frequency pulse current generated cannot be accurately detected by the current sensor, thereby affecting the accuracy of the state of charge estimation; another commonly used SOC estimation method is the OCV (Open Circuit Voltage) method, which uses the corresponding relationship between the battery's terminal voltage under no-load conditions and its SOC to establish an OCV-SOC curve to estimate the battery's state of charge. However, in actual operation, the battery needs to be in a static state for a long time to obtain a stable OCV value. However, in actual driving, it is difficult for the battery to have enough time to be static, which makes it difficult for the OCV method to accurately estimate the SOC in real time.

[0004] In summary, there are still limitations when facing the problem of battery SOC estimation under pulse heating conditions, which affects the accuracy of battery SOC estimation. Therefore, a SOC calibration strategy that can adapt to pulse heating conditions is developed to ensure that the battery SOC can be accurately and reliably estimated after using the pulse heating function, avoiding problems such as undervoltage, lithium deposition, and power drop caused by inaccurate SOC state identification. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present application discloses a battery state of charge calibration method, system, vehicle-mounted terminal and storage medium, which are used to solve the technical problem in the prior art that the battery state of charge cannot be accurately estimated after pulse heating.

[0006] In a first aspect, the present application provides a battery state of charge calibration method, the method comprising: obtaining battery parameters, the battery parameters comprising state parameters and a first change relationship between voltage and time under a preset discharge current after pulse heating, the state parameters comprising a healthy state, a first state of charge before pulse heating, and a temperature after pulse heating; matching the first characteristic parameters of the battery from a battery characteristic matrix according to the state parameters, the battery characteristic matrix being constructed according to characteristic parameters under different state parameters, the characteristic parameters comprising open circuit voltage, ohmic internal resistance, polarization internal resistance, and polarization capacitance; fitting the first characteristic parameters with the discharge current to determine a second change relationship between voltage and time; calibrating the first state of charge according to a first deviation between the second change relationship and the first change relationship to determine a second charge state after pulse heating.

[0007] In one embodiment of the present application, the fitting of the first characteristic parameter and the discharge current to determine the second variation relationship between voltage and time includes: determining the discharge duration according to the first variation relationship; inputting the first characteristic parameter and the discharge current into a battery equivalent circuit model, and recording a voltage response signal, wherein the battery equivalent circuit model is used to simulate the voltage response of the battery under different characteristic parameters and different discharge currents; and determining the second variation relationship according to the voltage response signal and the discharge duration.

[0008] In one embodiment of the present application, the first state of charge is calibrated according to the first deviation between the second change relationship and the first change relationship to determine the second charge state after pulse heating, including: comparing the first deviation with a preset deviation threshold; if the first deviation is less than or equal to the deviation threshold, taking the first charge state as the second charge state; if the first deviation is greater than the deviation threshold, adjusting the first charge state at least once according to a preset adjustment step to obtain the second charge state.

[0009] In one embodiment of the present application, the first charge state is adjusted at least once according to a preset adjustment step to obtain the second charge state, including: matching the second characteristic parameter of the battery from the battery characteristic matrix according to the adjusted third charge state, the health state and the temperature; determining a third change relationship of voltage with time according to the second characteristic parameter and the discharge current, and determining a second deviation between the third change relationship and the first change relationship; if the second deviation is less than or equal to the deviation threshold, using the third charge state as the second charge state; if the second deviation is greater than the deviation threshold, continuing to adjust the third charge state according to the adjustment step until the deviation condition is met to obtain the second charge state.

[0010] In one embodiment of the present application, the calculation method of the first deviation includes: calculating a first average change rate of the voltage over time based on the first change relationship, and calculating a second average change rate of the voltage over time based on the second change relationship; calculating a relative error between the first average change rate and the second average change rate to obtain the first deviation.

[0011] In one embodiment of the present application, matching the first characteristic parameter of the battery from the battery characteristic matrix according to the state parameter includes: matching a sub-matrix set corresponding to the health state from the battery characteristic matrix according to the health state, the sub-matrix set including an open circuit voltage matrix, an ohmic internal resistance matrix, a polarization internal resistance matrix and a polarization capacitance matrix; according to the first state of charge and the temperature, matching the open circuit voltage matrix, the ohmic internal resistance matrix, the polarization internal resistance matrix and the polarization capacitance matrix respectively to obtain the first open circuit voltage, the first ohmic internal resistance, the first polarization internal resistance and the first polarization capacitance corresponding to the first state of charge and the temperature.

[0012] In one embodiment of the present application, the method for obtaining the first change relationship includes: after pulse heating, discharging the battery according to the discharge current, and the discharge current is set according to the temperature and the first charge state; recording the change of voltage over time during the discharge process to obtain the first change relationship.

[0013] In a second aspect, the present application provides a battery state of charge calibration system, the system comprising: an acquisition module for acquiring battery parameters, the battery parameters comprising state parameters and a first change relationship between voltage and time under a preset discharge current, the state parameters comprising a healthy state, a first state of charge before pulse heating, and a temperature after pulse heating; a matching module for matching the first characteristic parameters of the battery from a battery characteristic matrix according to the state parameters, the battery characteristic matrix being constructed according to characteristic parameters under different state parameters, the characteristic parameters comprising open circuit voltage, ohmic internal resistance, polarization internal resistance, and polarization capacitance; a determination module for fitting the first characteristic parameter with the discharge current to determine a second change relationship between voltage and time; a calibration module for calibrating the first state of charge according to a first deviation between the second change relationship and the first change relationship, and determining a second charge state after pulse heating.

[0014] In a third aspect, the present application provides a vehicle-mounted terminal, comprising: one or more processors; a storage device for storing one or more programs, when the one or more programs are executed by one or more processors, the vehicle-mounted terminal implements the battery state of charge calibration method described in the first aspect.

[0015] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor of a computer, the computer executes the battery state of charge calibration method as described in the first aspect.

[0016] As described above, the battery state of charge calibration method, system, vehicle terminal and storage medium provided by the embodiments of the present application have the following beneficial effects:

[0017] First, the battery parameters are obtained, and the battery parameters include state parameters and a first variation relationship between voltage and time at a preset discharge current after pulse heating, wherein the state parameters include a healthy state, a first state of charge before pulse heating, and a temperature after pulse heating, so as to match the first characteristic parameters of the battery from a battery characteristic matrix according to the state parameters, and the battery characteristic matrix is ​​constructed according to characteristic parameters under different state parameters, wherein the characteristic parameters include open circuit voltage, ohmic internal resistance, polarization internal resistance, and polarization capacitance, and then the first characteristic parameters are fitted with the discharge current to determine the second variation relationship between voltage and time, and finally based on According to the first deviation between the second change relationship and the first change relationship, the first state of charge is calibrated to determine the second state of charge after pulse heating. Combined with the health status of the battery, the temperature after pulse heating and other influencing factors, the deviation between the theoretical voltage response and the actual voltage response after pulse heating is used to map the battery characteristic parameters and the state of charge through the battery characteristic matrix to determine whether the sought charge deviation is accurate, thereby accurately calibrating the state of charge of the battery after pulse heating, improving the accuracy of the state of charge estimation, and avoiding problems such as undervoltage, lithium deposition, and power drop caused by inaccurate state of charge estimation.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0020] Figure 1 is a schematic diagram of an implementation environment of a battery state of charge calibration system shown in an exemplary embodiment of the present application;

[0021] Figure 2 is a flow chart of a battery state of charge calibration method shown in an exemplary embodiment of the present application;

[0022] Figure 3 is a schematic diagram of an HPPC test result shown by an exemplary embodiment of the present application;

[0023] Figure 4 is a block diagram of a battery state of charge calibration system shown in an exemplary embodiment of the present application;

[0024] Figure 5It is a structural schematic diagram of a vehicle-mounted terminal provided in one embodiment of the present application. DETAILED DESCRIPTION

[0025] The following will describe the implementation methods of the present application with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application, not for limiting the scope of protection of the present application.

[0026] It should be noted that the illustrations provided in the following embodiments are only used to illustrate the basic concept of the present application in a schematic manner, and therefore the illustrations only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the form, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0027] In the following description, a large number of details are discussed to provide a more thorough explanation of the embodiments of the present application. However, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present application difficult to understand.

[0028] First of all, it should be noted that pulse heating technology is a technology that generates heat inside the battery by applying high-frequency pulse current to the battery, thereby rapidly raising the temperature of the battery and improving its low-temperature performance. While improving the low-temperature performance of the battery, the temperature, internal resistance and voltage of the battery will change during the pulse heating process, affecting the accuracy of SOC estimation. At present, the commonly used SOC estimation methods include the ampere-hour integration method and the OCV method. Among them, the ampere-hour integration method is to calculate the change in the charge of the battery by real-time monitoring of the charge and discharge current of the battery and performing an integral operation on it. The OCV method uses the corresponding relationship between the terminal voltage of the battery under no-load conditions and its SOC to establish an OCV-SOC curve to estimate the state of charge of the battery. However, the inventors of this application have found that the two methods still have limitations for the problem of battery SOC estimation under pulse heating conditions, which affects the accuracy of battery SOC estimation, resulting in undervoltage, lithium precipitation, and power drop due to inaccurate SOC state recognition.

[0029] Therefore, see Figure 1 , Figure 1 FIG. 1 is a schematic diagram of an implementation environment of a battery state of charge calibration system shown in an exemplary embodiment of the present application. Figure 1 As shown, the implementation environment includes a vehicle 110 and a battery state of charge calibration system 120, wherein the battery state of charge calibration system 120 is embedded in the vehicle 110, and is used to realize the calibration of the battery state of charge in the vehicle 110. The battery state of charge calibration system 120 includes but is not limited to a vehicle system, an on-board computer, etc., and combines the health status of the battery, the temperature after pulse heating and other influencing factors, and uses the deviation between the theoretical voltage response and the actual voltage response after pulse heating to map the battery characteristic parameters and the state of charge through a battery characteristic matrix to determine whether the sought charge deviation is accurate, thereby accurately calibrating the battery state of charge after pulse heating, thereby improving the accuracy of the state of charge estimation, and avoiding problems such as undervoltage, lithium deposition, and power drop caused by inaccurate state of charge estimation.

[0030] See also Figure 2 , Figure 2 is a flow chart of a battery state of charge calibration method shown in an exemplary embodiment of the present application. The method can be applied to Figure 1 The implementation environment shown is a schematic diagram. It should be understood that the method may also be applicable to other exemplary implementation environments, and this embodiment does not limit the implementation environment to which the method is applicable.

[0031] like Figure 2 As shown, in an exemplary embodiment, the battery state of charge calibration method includes at least steps S210 to S240, which are described in detail as follows:

[0032] Step S210, obtaining battery parameters, the battery parameters include state parameters and a first change relationship between voltage and time at a preset discharge current after pulse heating, the state parameters include a healthy state, a first state of charge before pulse heating, and a temperature after pulse heating.

[0033] Among them, the first change relationship between voltage and time is monitored and obtained during the discharge process of the battery after pulse heating; the SOH (State of Health) health status can be directly obtained from the health status function module; the first state of charge before pulse heating can be obtained by real-time monitoring and calculation by the battery management system; the temperature after pulse heating can be obtained by measuring the temperature sensor.

[0034] In addition, the battery for charge state calibration may be a lithium-ion battery, a nickel-hydrogen battery, a lead-acid battery, a solid-state battery, a sodium-ion battery, and the like.

[0035] Specifically, the first change relationship is obtained by: after pulse heating, discharging the battery according to a discharge current, wherein the discharge current is set according to the temperature and the first charge state; and recording the change of the voltage over time during the discharge process to obtain the first change relationship.

[0036] It should be noted that in order to ensure the safe operation of the battery under high power demand, the maximum short-term current value that the battery can safely withstand when the battery is discharged corresponds to the temperature and state of charge at the time, that is, a specific current value corresponds to a specific temperature and state of charge.

[0037] In this embodiment, considering that the precise state of charge after pulse heating is unknown, the state of charge before pulse heating is used to determine the discharge current, that is, the discharge current is set according to the temperature after pulse heating and the state of charge before pulse heating, so that the battery is discharged according to the discharge current, and the change of voltage over time during the discharge process is monitored, and the first change relationship (denoted as U 1-t ) is regarded as the actual voltage response of the battery after pulse heating.

[0038] In this way, the method of determining the discharge current in combination with the temperature and the state of charge ensures the safety of the discharge process and also ensures the reliability of the obtained first change relationship.

[0039] In a possible embodiment, in order to further ensure the safety of battery discharge, the discharge current is set according to the temperature and the first state of charge. 0 ) Determine the maximum short-time current value I allowed by the battery max0 , according to the preset coefficient, I max0 Calculate and obtain the final discharge current I 0 For example, I 0 =75%I max0 .

[0040] In a possible embodiment, considering the impact of long-term discharge on the battery state, the battery is discharged according to a preset time, and the preset time is short enough to capture the transient response of the battery voltage during discharge, so that the accuracy of the charge state estimation can be prevented from being affected by the increase in battery temperature due to long-term discharge. For example, the discharge time is 10S.

[0041] Step S220, matching the first characteristic parameter of the battery from the battery characteristic matrix according to the state parameter, the battery characteristic matrix is ​​constructed according to the characteristic parameters under different state parameters, and the characteristic parameters include open circuit voltage, ohmic internal resistance, polarization internal resistance and polarization capacitance.

[0042] Among them, OCV (Open Circuit Voltage) refers to the terminal voltage of the battery when there is no load; Ohmic internal resistance refers to the resistance of the electron and ion conduction path inside the battery, polarization internal resistance refers to the resistance caused by the incomplete chemical reaction inside the battery and the resistance during the charge transfer process, and polarization capacitance refers to the ability of the battery to store charge. In addition, the characteristic parameters (i.e., open circuit voltage, ohmic internal resistance, polarization internal resistance and polarization capacitance) of the battery are different under different state parameters (i.e., health state, state of charge, temperature).

[0043] In this example, the battery characteristic matrix includes values ​​of various characteristic parameters under different state parameters. Therefore, corresponding characteristic parameters can be matched from the battery characteristic matrix according to specific state parameters.

[0044] In a possible embodiment, the construction method of the battery characteristic matrix includes: (1) testing the battery voltage response under different health states, temperatures, and charge states: (a) fully charging the battery according to the battery fast charging strategy; (b) standing for a period of time (e.g., 1 hour); (c) constant current pulse test: at 75% I max Discharge 10S, I max is the maximum allowable 10s pulse discharge current of the battery; (d) discharge △SOC (△SOC can be selected according to the computing power of the vehicle and the required progress); (e) stand for a period of time (for example, 1 hour); (f) repeat (c) to (e) until the battery power is consumed to the lower limit of the battery allowable SOC (for example, 3%); (g) repeat (a) to (f) to test the battery in different health states (100%-end of life) and different temperatures (allowable temperature range of power battery, for example -20℃-55℃). (2) obtain the characteristic parameters of the battery at different temperatures, charge states, and health states through parameter identification.

[0045] In this embodiment, a standard HPPC (Hybrid Pulse Power Characterization) test method may be used to test characteristic parameters of batteries at different temperatures, charge states, and health states.

[0046] See also Figure 3 , Figure 3 is a schematic diagram of an HPPC test result shown in an exemplary embodiment of the present application, such as Figure 3As shown, the first cycle - initial stage: if the battery is in a fully charged state (i.e. SOC = 1), the voltage is at the highest value. At this time, the battery is allowed to rest for a certain period of time in order to stabilize its internal state, and then discharge. Subsequently, the battery begins to discharge at a certain discharge rate, and applies a short high current pulse at a fixed interval (such as every 10 seconds); the second cycle - continued discharge: in this cycle, the battery state of charge decreases to a certain extent, the battery continues to discharge and receives the same pulse current treatment, and then after each cycle, the battery will have a longer rest time to allow the internal state of the battery to stabilize again. In each cycle, V 1 Represents the voltage before the pulse, V 2 Represents the voltage after the pulse, specifically the voltage at the end of the pulse current, V 3 It indicates the voltage when the battery voltage returns to steady state after the pulse current ends. By applying a series of pulse currents and combining static and dynamic tests, key parameters such as the battery's open circuit voltage, ohmic internal resistance, polarization internal resistance, and polarization capacitance can be effectively evaluated.

[0047] During the test, the calculation formula of ohmic internal resistance is:

[0048]

[0049] Among them, R o Indicates the ohmic internal resistance, V 1 Represents the voltage before the pulse, V 2 represents the voltage after the pulse, and I represents the applied pulse current.

[0050] The calculation formula of polarization internal resistance is:

[0051]

[0052] Among them, R p Represents polarization internal resistance, V 2 Represents the voltage after the pulse, specifically the voltage at the end of the pulse current, V 3 It represents the voltage when the battery voltage returns to a steady state after the pulse current ends, and I represents the applied pulse current.

[0053] In addition, the polarization capacitance C p It can be determined by the response of the terminal voltage within a period of time after the pulse, and the polarization capacitance value that best matches the experimental data can be identified within a given range by an exhaustive method. For example, a polarization capacitance value range (150F to 80000F) is set, and for each candidate polarization capacitance value, the circuit model is used to predict the voltage response of the battery after the pulse, and the predicted voltage response is compared with the measured data to find the polarization capacitance value that minimizes the error.

[0054] Please refer to Tables 1 to 3, which show the changes in ohmic internal resistance, polarization internal resistance and polarization capacitance with temperature and charge state in a certain health state (for example, 90%).

[0055] Table 1: Ohmic internal resistance

[0056]

[0057] Table 2: Polarization internal resistance R p

[0058]

[0059] Table 3: Polarization capacitance C p

[0060]

[0061] For different health states, temperatures, and charge states, the open circuit voltage U OCV The test can be extracted from the HPPC test data, usually a period of time after the end of the pulse current, such as the open circuit voltage after 150 seconds. By recording the open circuit voltage at different temperatures, charge states, and healthy states, the corresponding relationship between the open circuit voltage and temperature, charge state, and healthy state can be established.

[0062] In one embodiment, a first characteristic parameter of a battery is matched from a battery characteristic matrix according to a state parameter, including: according to a health state, matching a sub-matrix set corresponding to the health state from the battery characteristic matrix, the sub-matrix set including an open circuit voltage matrix, an ohmic internal resistance matrix, a polarization internal resistance matrix, and a polarization capacitance matrix; according to a first state of charge and a temperature, matching the open circuit voltage matrix, the ohmic internal resistance matrix, the polarization internal resistance matrix, and the polarization capacitance matrix respectively to obtain a first open circuit voltage, a first ohmic internal resistance, a first polarization internal resistance, and a first polarization capacitance corresponding to the first state of charge and the temperature.

[0063] Among them, the battery characteristic matrix includes multiple sub-matrix sets, each corresponding to a different health state, and each sub-matrix set includes a road voltage matrix, an ohmic internal resistance matrix, a polarization internal resistance matrix and a polarization capacitance matrix under a specific health state.

[0064] In this embodiment, according to the current health state of the battery, the sub-matrix set corresponding to the health state is first matched from the battery characteristic matrix, and then the open circuit voltage, ohmic internal resistance, polarization internal resistance and polarization capacitance are matched from the sub-matrix set according to the temperature and the first state of charge, which are recorded as the health state, temperature, first open circuit voltage U under the first state of charge. OCV0 、First ohm internal resistance R o0 , the first polarization internal resistance R p0 With the first polarization capacitor C p0 .

[0065] Step S230: fitting the first characteristic parameter with the discharge current to determine a second variation relationship between the voltage and time.

[0066] In the embodiment, according to the first open circuit voltage U OCV0 、First ohm internal resistance R o0 , the first polarization internal resistance R p0 , the first polarization capacitor C p0 and I 0 , determine the second variation relationship of voltage over time.

[0067] Specifically, fitting is performed based on the first characteristic parameter and the discharge current to determine a second variation relationship between the voltage and time, including: determining the discharge duration based on the first variation relationship; inputting the first characteristic parameter and the discharge current into a battery equivalent circuit model, recording a voltage response signal, and the battery equivalent circuit model is used to simulate the voltage response of the battery under different characteristic parameters and different discharge currents; and determining the second variation relationship based on the voltage response signal and the discharge duration.

[0068] In order to make the second change relationship and the first change relationship represent the change of voltage over time within the same time period, the duration of the first change relationship is first confirmed, thereby determining the duration of the second change relationship.

[0069] In this embodiment, the battery equivalent circuit model simulates the voltage and current parameters of the battery by using circuit elements such as resistors, polarized capacitors and constant phases, and can be a first-order RC (resistance-capacitance) equivalent circuit model. The battery equivalent circuit model is composed of a terminal voltage U, an open circuit voltage U ocv 、Ohmic internal resistance R o , Polarization internal resistance R p and polarization capacitance C p The polarization internal resistance R p and polarization capacitance C p It is a parallel structure, and the dynamic equation of the battery equivalent circuit model is:

[0070]

[0071] The first part represents the polarization voltage U p The second part represents the change rate over time and the terminal voltage U and the open circuit voltage U OCV , polarization voltage U p And the ohmic internal resistance U p The relationship between Indicates the polarization voltage U p The rate of change over time, C p Represents polarized capacitance, R p represents the polarization internal resistance, and I represents the discharge current.

[0072] Discretize formula (3) to obtain:

[0073] U(t)=-I(t)·R o -U p (t) Formula (4)

[0074]

[0075] Where t represents time, U(t) represents the terminal voltage at time t, I(t) represents the discharge current at time t, R o Indicates the ohmic internal resistance, U p (t) represents the polarization voltage at time t, U p (t-1) represents the polarization voltage at t-1, C p Represents polarized capacitance, R p Represents polarization internal resistance.

[0076] In this embodiment, the first open circuit voltage U OCV0 、First ohm internal resistance R o0 , the first polarization internal resistance R p0 , the first polarization capacitor C p0 and I 0 , substitute into formula (4) and (5), simulate the dynamic reaction of the battery, obtain the voltage response signal, and then determine the second change relationship of voltage over time according to the discharge time (denoted as U 2-t ), which is regarded as the theoretical voltage response of the battery after pulse heating.

[0077] It should also be noted that the battery parameters also include the terminal voltage U after pulse heating 0 , U 0 is the terminal voltage value at the starting moment of the first change relationship and the second change relationship.

[0078] Step S240: calibrate the first state of charge according to a first deviation between the second change relationship and the first change relationship to determine a second state of charge after pulse heating.

[0079] In this embodiment, the first change relationship is the actual voltage response of the battery after pulse heating, and the second change relationship is the theoretical voltage response of the battery after pulse heating. Because the state of charge after pulse heating is unknown, the first state of charge before pulse heating is used when confirming the first change relationship and the second change relationship. Therefore, there is a certain deviation between the first change relationship and the second change relationship, and the deviation is caused by the inaccurate first state of charge. Therefore, the first state of charge is calibrated according to the first deviation between the first change relationship and the second change relationship to obtain the accurate second state of charge after pulse heating.

[0080] Specifically, according to the first deviation between the second change relationship and the first change relationship, the first charge state is calibrated to determine the second charge state after pulse heating, including: comparing the first deviation with a preset deviation threshold; if the first deviation is less than or equal to the deviation threshold, taking the first charge state as the second charge state; if the first deviation is greater than the deviation threshold, adjusting the first charge state at least once according to a preset adjustment step to obtain the second charge state.

[0081] In this embodiment, if the first deviation is less than or equal to the deviation threshold, that is, A 1 ≤A', indicating that the first state of charge is correct, therefore, the second state of charge is the first state of charge, that is, SOC'=SOC 0 , such as A 1 >A', the surface first state of charge is inaccurate, so according to the preset adjustment step △SOC to SOC 0 At least one adjustment is performed to calibrate the state of charge to obtain an accurate SOC'.

[0082] Specifically, the calculation method of the first deviation includes: calculating the first average change rate of the voltage over time according to the first change relationship, and calculating the second average change rate of the voltage over time according to the second change relationship; calculating the relative error between the first average change rate and the second average change rate to obtain the first deviation.

[0083] In this embodiment, the calculation formula of the first deviation is:

[0084] A 1 =abs(P 2 –P 1 ) / P 1 Formula (6)

[0085] Among them, A 1 Indicates the first deviation, P 2 represents the second average rate of change, P 1 Represents the first average rate of change.

[0086] As a possible embodiment, the calculation of the average change rate includes: calculating the time difference between the end time and the start time in the first change relationship, and calculating the voltage difference between the voltage at the end time and the voltage at the start time, and then calculating the ratio between the voltage difference and the time difference to obtain the average change rate.

[0087] As a possible embodiment, the change relationship may be divided into multiple segments, and then the change rate of each segment is calculated, and finally the average value of the multiple change rates is calculated to obtain the average change rate.

[0088] In one embodiment, the first charge state is adjusted at least once according to a preset adjustment step to obtain a second charge state, including: matching a second characteristic parameter of the battery from a battery characteristic matrix according to the adjusted third charge state, health state and temperature; determining a third change relationship of voltage with time according to the second characteristic parameter and the discharge current, and determining a second deviation between the third change relationship and the first change relationship; if the second deviation is less than or equal to a deviation threshold, taking the third charge state as the second charge state; if the second deviation is greater than the deviation threshold, continuing to adjust the third charge state according to the adjustment step until the deviation condition is met to obtain the second charge state.

[0089] In this embodiment, the SOC is adjusted according to the preset adjustment step ΔSOC. 0 After one adjustment, the third state of charge SOC is obtained 1 , then according to SOC 1 As well as the health status and temperature obtained at the beginning, the second characteristic parameter of the battery, namely the second open circuit voltage U, is matched from the battery characteristic matrix. OCV1 、The second ohm internal resistance R o1 , the second polarization internal resistance R p1 With the second polarization capacitor C p1 , and then the second open circuit voltage U PCV1 、The second ohm internal resistance R o1 , the second polarization internal resistance R p1 , the second polarization capacitor C p1 and I 0 Substituting into the above formulas (4) and (5), we can obtain the third relationship of voltage change over time: 3-t , at this time, calculate U 3-t with U 1-t The second deviation A 2 , if A 2 Satisfy the deviation condition, that is, A 2 ≤A', then SOC'=SOC 0 -△SOC, that is, SOC' = SOC 1 If A 2 If the deviation condition is not met, then continue to adjust SOC according to △SOC. 1 Adjust to obtain SOC 2 , continue to match characteristic parameters, obtain change relationships and calculate deviations until a certain deviation meets the deviation condition, and obtain the final state of charge, that is, SOC'=SOC n .

[0090] In this way, by gradually adjusting the first state of charge before pulse heating according to the adjustment step, the state of charge is calibrated, so that the state of charge after pulse heating can be accurately estimated.

[0091] In a possible embodiment, the adjustment step size can be flexibly adjusted, that is, different adjustment step sizes are set according to the size of the deviation. Specifically, the larger the deviation, the larger the adjustment step size. In this way, the first state of charge can be quickly converged to obtain the final state of charge when the deviation is too large, and the problem of excessive adjustment when the deviation is too small, thereby increasing the deviation, can be avoided.

[0092] The above-mentioned battery state of charge calibration method first obtains battery parameters, which include state parameters and a first change relationship between voltage and time under a preset discharge current after pulse heating, wherein the state parameters include a healthy state, a first state of charge before pulse heating, and a temperature after pulse heating, so as to match the first characteristic parameters of the battery from a battery characteristic matrix according to the state parameters, and the battery characteristic matrix is ​​constructed according to characteristic parameters under different state parameters, wherein the characteristic parameters include open circuit voltage, ohmic internal resistance, polarization internal resistance, and polarization capacitance, and then the first characteristic parameters are fitted with the discharge current to determine the second change relationship between voltage and time. Finally, according to the first deviation of the second change relationship and the first change relationship, the first state of charge is calibrated to determine the second state of charge after pulse heating. Combined with the health status of the battery, the temperature after pulse heating and other influencing factors, the deviation between the theoretical voltage response and the actual voltage response after pulse heating is used to map the battery characteristic parameters and the state of charge through the battery characteristic matrix to determine whether the sought charge deviation is accurate, thereby accurately calibrating the state of charge of the battery after pulse heating, improving the accuracy of the state of charge estimation, and avoiding problems such as undervoltage, lithium deposition, and power drop caused by inaccurate state of charge estimation.

[0093] See also Figure 4 , Figure 4 is a block diagram of a battery state of charge calibration system shown in an exemplary embodiment of the present application. The system can be applied to Figure 1 The implementation environment shown is a schematic diagram. It should be understood that the system may also be applicable to other exemplary implementation environments, and this embodiment does not limit the implementation environment to which the system is applicable.

[0094] like Figure 4 As shown, in an exemplary embodiment, the battery state of charge calibration system 400 includes at least an acquisition module 410, a matching module 420, a determination module 430 and a calibration module 440, which are described in detail as follows:

[0095] An acquisition module 410 is used to acquire battery parameters, the battery parameters including state parameters and a first variation relationship between voltage and time at a preset discharge current, the state parameters including a health state, a first state of charge before pulse heating, and a temperature after pulse heating;

[0096] A matching module 420, configured to match a first characteristic parameter of the battery from a battery characteristic matrix according to the state parameter, wherein the battery characteristic matrix is ​​constructed according to characteristic parameters under different state parameters, and the characteristic parameters include open circuit voltage, ohmic internal resistance, polarization internal resistance, and polarization capacitance;

[0097] A determination module 430 is used to determine a second variation relationship between voltage and time by fitting the first characteristic parameter and the discharge current;

[0098] The calibration module 440 is used to calibrate the first state of charge according to a first deviation between the second change relationship and the first change relationship, and determine a second state of charge after pulse heating.

[0099] It should be noted that the battery state of charge calibration system provided in the above embodiment and the battery state of charge calibration method provided in the above embodiment belong to the same concept, wherein the contents of the operations performed by each module have been described in detail in the method embodiment and will not be repeated here.

[0100] See also Figure 5 , Figure 5 It is a structural schematic diagram of a vehicle-mounted terminal provided in one embodiment of the present application. Figure 5 The structure diagram of the computer system of the vehicle terminal suitable for implementing the embodiment of the present application is shown. It should be noted that: Figure 5 The computer system 500 of the vehicle-mounted terminal shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0101] like Figure 5 As shown, the computer system 500 includes a central processing unit (CPU) 501, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 502 or the program loaded from the storage part 508 to the random access memory (RAM) 503, such as executing the method in the above embodiment. In the RAM 503, various programs and data required for system operation are also stored. The CPU 501, ROM 502 and RAM 503 are connected to each other through a bus 504. An input / output (I / O) interface 505 is also connected to the bus 504.

[0102] The following components are connected to the I / O interface 505: an input section 506 including a keyboard, a mouse, etc.; an output section 507 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker; a storage section 508 including a hard disk, etc.; and a communication section 509 including a network interface card such as a LAN (Local Area Network) card, a modem, etc. The communication section 509 performs communication processing via a network such as the Internet. A drive 510 is also connected to the I / O interface 505 as needed. A removable medium 511, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 510 as needed so that a computer program read therefrom is installed into the storage section 508 as needed.

[0103] In particular, according to an embodiment of the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a computer program for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication section 509, and / or installed from a removable medium 511. When the computer program is executed by a central processing unit (CPU) 501, various functions defined in the system of the present application are executed.

[0104] The present application also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor of a computer, the computer executes the battery state of charge calibration method as described above. The computer-readable storage medium may be included in the electronic device described in the above embodiment, or may exist independently without being assembled into the electronic device.

[0105] It should be noted that the computer-readable medium shown in the embodiment of the present application can be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium can be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media can include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, wherein a computer-readable computer program is carried. This propagated data signal can take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above. A computer-readable signal medium 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. A computer program contained on a computer-readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0106] The flowchart and block diagram in the accompanying drawings illustrate the possible architecture, functions and operations of the system, method and computer program product according to various embodiments of the present application. Wherein, each box in the flowchart or block diagram can represent a module, a program segment, or a part of the code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for realizing 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 boxes represented in succession 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 or flowchart, and the combination of boxes in the block diagram or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0107] The units involved in the embodiments described in this application may be implemented by software or hardware, and the units described may also be set in a processor. The names of these units do not, in some cases, constitute limitations on the units themselves.

[0108] The above embodiments are merely illustrative of the principles and effects of the present application, and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A battery state of charge calibration method, characterized in that: The method comprises: Acquire battery parameters, the battery parameters including state parameters and a first variation relationship between voltage and time at a preset discharge current after pulse heating, the state parameters including a healthy state, a first state of charge before pulse heating, and a temperature after pulse heating; Matching a first characteristic parameter of the battery from a battery characteristic matrix according to the state parameter, wherein the battery characteristic matrix is ​​constructed according to characteristic parameters under different state parameters, wherein the characteristic parameters include open circuit voltage, ohmic internal resistance, polarization internal resistance, and polarization capacitance; Determine a second variation relationship between voltage and time by fitting the first characteristic parameter and the discharge current; The first state of charge is calibrated according to a first deviation between the second change relationship and the first change relationship to determine a second state of charge after pulse heating.

2. The battery state of charge calibration method according to claim 1, characterized in that: The fitting of the first characteristic parameter and the discharge current to determine a second variation relationship between voltage and time includes: Determining a discharge duration according to the first change relationship; Inputting the first characteristic parameter and the discharge current into a battery equivalent circuit model, and recording a voltage response signal, wherein the battery equivalent circuit model is used to simulate the voltage response of the battery under different characteristic parameters and different discharge currents; The second change relationship is determined according to the voltage response signal and the discharge duration.

3. The battery state of charge calibration method according to claim 1, characterized in that: The step of calibrating the first state of charge according to a first deviation between the second change relationship and the first change relationship to determine a second state of charge after pulse heating includes: comparing the first deviation with a preset deviation threshold; If the first deviation is less than or equal to the deviation threshold, taking the first charge state as the second charge state; If the first deviation is greater than the deviation threshold, the first charge state is adjusted at least once according to a preset adjustment step to obtain the second charge state.

4. The battery state of charge calibration method according to claim 3, characterized in that: The step of adjusting the first charge state at least once according to a preset adjustment step length to obtain the second charge state includes: matching a second characteristic parameter of a battery from the battery characteristic matrix according to the adjusted third state of charge, the health state, and the temperature; determining a third variation relationship of voltage over time according to the second characteristic parameter and the discharge current, and determining a second deviation between the third variation relationship and the first variation relationship; If the second deviation is less than or equal to the deviation threshold, taking the third charge state as the second charge state; If the second deviation is greater than the deviation threshold, the third charge state is continuously adjusted according to the adjustment step until the deviation condition is met, thereby obtaining the second charge state.

5. The battery state of charge calibration method according to claim 3, characterized in that: The calculation method of the first deviation includes: Calculating a first average rate of change of the voltage over time according to the first change relationship, and calculating a second average rate of change of the voltage over time according to the second change relationship; A relative error between the first average change rate and the second average change rate is calculated to obtain the first deviation.

6. The battery state of charge calibration method according to claim 1, characterized in that: The matching of the first characteristic parameter of the battery from the battery characteristic matrix according to the state parameter includes: According to the health state, matching a sub-matrix set corresponding to the health state from the battery characteristic matrix, the sub-matrix set including an open circuit voltage matrix, an ohmic internal resistance matrix, a polarization internal resistance matrix, and a polarization capacitance matrix; According to the first state of charge and the temperature, the open circuit voltage matrix, the ohmic internal resistance matrix, the polarization internal resistance matrix, and the polarization capacitance matrix are matched respectively to obtain the first open circuit voltage, the first ohmic internal resistance, the first polarization internal resistance, and the first polarization capacitance corresponding to the first state of charge and the temperature.

7. The battery state of charge calibration method according to any one of claims 1 to 6, characterized in that: The method for obtaining the first change relationship includes: After pulse heating, discharging the battery according to the discharge current, wherein the discharge current is set according to the temperature and the first state of charge; The change of voltage over time during the discharge process is recorded to obtain the first change relationship.

8. A battery state of charge calibration system, characterized in that: The system comprises: an acquisition module, configured to acquire battery parameters, wherein the battery parameters include a state parameter and a first variation relationship between voltage and time at a preset discharge current, wherein the state parameter includes a health state, a first state of charge before pulse heating, and a temperature after pulse heating; A matching module, used for matching a first characteristic parameter of a battery from a battery characteristic matrix according to the state parameter, wherein the battery characteristic matrix is ​​constructed according to characteristic parameters under different state parameters, wherein the characteristic parameters include open circuit voltage, ohmic internal resistance, polarization internal resistance and polarization capacitance; A determination module, configured to determine a second variation relationship between voltage and time by fitting the first characteristic parameter and the discharge current; A calibration module is used to calibrate the first state of charge according to a first deviation between the second change relationship and the first change relationship, and determine a second state of charge after pulse heating.

9. A vehicle-mounted terminal, characterized in that: include: one or more processors; A storage device for storing one or more programs, which, when executed by the one or more processors, enables the vehicle-mounted terminal to implement the battery state of charge calibration method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor of a computer, the computer is caused to execute the battery state of charge calibration method as claimed in any one of claims 1 to 7.

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