Method, device and storage medium for estimating maximum charge and discharge current of battery

Abstract

The present invention discloses a method, device and storage medium for estimating the maximum charge and discharge current of a battery, and relates to the field of automotive batteries. The method includes: reading the voltage sequence value and current sequence value of the battery to be estimated, wherein the voltage sequence value includes the terminal voltage value at multiple consecutive moments, and the current sequence value includes the current value at multiple consecutive moments; using the recursive least squares method, according to the voltage sequence value and the current sequence value of the battery to be estimated, obtaining the parameters to be estimated at the current moment; obtaining the corresponding relationship between the parameters to be estimated and the battery characteristic parameters through the second-order RC equivalent battery model, and obtaining the battery characteristic parameters at the current moment according to the corresponding relationship between the parameters to be estimated and the battery characteristic parameters; according to the battery characteristic parameters at the current moment, obtaining the maximum charge and discharge current of the battery to be estimated at the current moment. The above method can improve the accuracy of the estimation result of the maximum charge and discharge current of the battery.

Description

Technical Field

[0001] The present invention relates to the field of automobile batteries, and in particular to a method, a device and a storage medium for estimating a maximum charge and discharge current of a battery. Background Art

[0002] With the continuous reduction of global oil energy and the increasing efforts to save energy and protect the environment, new energy vehicles have become the preferred product for the long-term development of the automotive industry, among which electric vehicles that use electricity as the power source and motors as the drive device have developed particularly significantly. As the core components of electric vehicles, power batteries and battery management systems have a direct impact on the vehicle's driving range, service life, safety performance, etc. Battery charge and discharge capacity (SOF), that is, the maximum charge and discharge current of the battery, is an important parameter for the battery management system to estimate the state, and its estimation result is crucial to the battery management system.

[0003] In the prior art, the estimation of the maximum charge and discharge current of a battery is mainly determined based on the battery temperature and the battery state of charge (SOC), that is, firstly, the corresponding relationship between multiple sets of temperatures, SOC values ​​and maximum discharge currents is obtained through experiments, and then the actual battery temperature and the estimated SOC value are measured to look up the experimental data table to obtain the maximum discharge current of the battery.

[0004] However, current estimation methods rely too much on experimental data. When the experimental data is insufficient or inaccurate, the accuracy of the estimation of the maximum charge and discharge current of the battery will be affected. Summary of the invention

[0005] In view of this, the present application provides a method, device and storage medium for estimating the maximum charge and discharge current of a battery, the main purpose of which is to solve the technical problem of low accuracy of the estimation result of the maximum charge and discharge current of the battery.

[0006] According to a first aspect of the present invention, a method for estimating a maximum charge and discharge current of a battery is provided, the method comprising:

[0007] Reading a voltage sequence value and a current sequence value of the battery to be estimated, wherein the voltage sequence value includes terminal voltage values ​​at multiple consecutive moments, and the current sequence value includes current values ​​at multiple consecutive moments;

[0008] Using the recursive least square method, the parameters to be estimated at the current moment are obtained according to the voltage sequence value and current sequence value of the battery to be estimated;

[0009] The corresponding relationship between the estimated parameter and the battery characteristic parameter is obtained through the second-order RC equivalent battery model, and the battery characteristic parameter at the current moment is obtained according to the corresponding relationship between the estimated parameter and the battery characteristic parameter;

[0010] According to the battery characteristic parameters at the current moment, the maximum charge and discharge current of the battery to be estimated at the current moment is obtained.

[0011] According to a second aspect of the present invention, there is provided a device for estimating a maximum charge and discharge current of a battery, the device comprising:

[0012] A data acquisition module, used to read the voltage sequence value and current sequence value of the battery to be estimated, wherein the voltage sequence value includes the terminal voltage values ​​at multiple consecutive moments, and the current sequence value includes the current values ​​at multiple consecutive moments;

[0013] The estimated parameter estimation module is used to obtain the estimated parameter at the current moment according to the voltage sequence value and current sequence value of the battery to be estimated by using the recursive least square method;

[0014] A battery characteristic parameter estimation module is used to obtain the corresponding relationship between the parameter to be estimated and the battery characteristic parameter through a second-order RC equivalent battery model, and obtain the battery characteristic parameter at the current moment according to the corresponding relationship between the parameter to be estimated and the battery characteristic parameter;

[0015] The maximum charge and discharge current estimation module is used to obtain the maximum charge and discharge current of the battery to be estimated at the current moment according to the battery characteristic parameters at the current moment.

[0016] According to a third aspect of the present invention, there is provided a storage medium having a computer program stored thereon, wherein the program, when executed by a processor, implements the above-mentioned method for estimating the maximum charge and discharge current of a battery.

[0017] According to a fourth aspect of the present invention, there is provided a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned method for estimating the maximum charge and discharge current of a battery when executing the program.

[0018] The present invention provides a method, device and storage medium for estimating the maximum charge and discharge current of a battery. The method first reads the voltage sequence value and current sequence value of the battery to be estimated, then estimates the parameter to be estimated at the current moment by using the least square method, and then obtains the corresponding relationship between the parameter to be estimated and the battery characteristic parameter according to the second-order RC equivalent battery model, thereby obtaining the battery characteristic parameter at the current moment through the corresponding relationship, and finally obtains the maximum charge and discharge current at the current moment according to the relationship between the battery characteristic parameter and the maximum charge and discharge current. The above method can accurately simulate the state of the battery through the second-order RC equivalent battery model, and the method combining the second-order RC equivalent battery model with the recursive least square method can also accurately estimate the parameter to be estimated and the battery characteristic parameter, thereby improving the accuracy of the battery characteristic parameter estimation result, and also improving the accuracy of the battery maximum charge and discharge current estimation result.

[0019] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 A schematic flow chart of a method for estimating a maximum charge and discharge current of a battery provided by an embodiment of the present invention is shown;

[0022] Figure 2 A schematic diagram of a second-order RC equivalent battery model provided by an embodiment of the present invention is shown;

[0023] Figure 3 A schematic flow chart of another method for estimating the maximum charge and discharge current of a battery provided by an embodiment of the present invention is shown;

[0024] Figure 4 A schematic flow chart of another method for estimating the maximum charge and discharge current of a battery provided by an embodiment of the present invention is shown;

[0025] Figure 5 A schematic structural diagram of a device for estimating maximum charge and discharge current of a battery provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0027] In one embodiment, Figure 1 As shown, a method for estimating the maximum charge and discharge current of a battery is provided, and the method is described by taking the application of the method to a computer device as an example, and the method includes the following steps:

[0028] 101. Read voltage sequence values ​​and current sequence values ​​of a battery to be estimated, wherein the voltage sequence values ​​include terminal voltage values ​​at multiple consecutive moments, and the current sequence values ​​include current values ​​at multiple consecutive moments.

[0029] Among them, the battery to be estimated refers to the battery for which the maximum charge and discharge current needs to be estimated. The voltage sequence value and current sequence value of the battery to be estimated refer to multiple groups of battery terminal voltage values ​​at continuous moments and multiple groups of current values ​​at continuous moments, wherein the continuous moments can be from the initial moment to the current moment; and the voltage sequence value and the current sequence value are both discrete data. For example, the voltage sequence value and the current sequence value can be the terminal voltage value at the initial moment, the terminal voltage value at the current moment, the terminal voltage value at the previous moment, the current value at the initial moment, the current value at the current moment, and the current value at the previous moment, etc. In addition, the voltage sequence value and the current sequence value can be read by a voltage and current sensor, and then stored in a database for use in the subsequent estimation of the maximum charge and discharge current of the battery. In this embodiment, the voltage and current parameter matrix and the relative matrix are required to estimate the maximum charge and discharge current of the battery, and both matrices are composed of terminal voltage values ​​and current values, wherein the terminal voltage value and the current value can be obtained in the database.

[0030] 102. Using a recursive least square method, obtain the parameter to be estimated at the current moment according to the voltage sequence value and the current sequence value of the battery to be estimated.

[0031] Among them, the recursive algorithm refers to the estimation of time-varying parameters by performing a series of recursive operations on the parameters of the previous moment to obtain the parameters of the current moment, and then recursively inferring the parameters of the next moment through the parameters of the current moment. Common recursive algorithms include: recursive least squares method, Kalman filter parameter estimation and recursive auxiliary variable method, etc. Among them, the recursive least squares method has the highest accuracy in estimating parameters.

[0032] Specifically, the basic idea of ​​recursive least squares method for estimating parameters is that new parameters are formed on the basis of old parameters and correction terms. In this embodiment, the voltage and current parameter matrix of the previous moment can be obtained through a series of change operations based on the voltage sequence value and the current sequence value of the previous moment read, so as to use the recursive least squares method, and perform recursive operations based on the voltage and current parameter matrix of the previous moment and the parameters to be estimated at the previous moment to obtain the parameters to be estimated at the current moment. Further, the parameters to be estimated at the current moment and the voltage and current parameter matrix of the current moment are recursively calculated using the recursive least squares method to obtain the parameters to be estimated at the next moment. Among them, the parameters to be estimated at the previous moment can be continuously corrected according to the changes of the parameters to be estimated set at the initial moment over time.

[0033] 103. Obtain a corresponding relationship between the parameter to be estimated and the battery characteristic parameter through a second-order RC equivalent battery model, and obtain the battery characteristic parameter at the current moment according to the corresponding relationship between the parameter to be estimated and the battery characteristic parameter.

[0034] Specifically, the maximum charge and discharge current of the battery to be estimated needs to be obtained with the help of the battery characteristic parameters. When calculating the battery parameters, many characteristic parameters cannot be directly measured. In this embodiment, by establishing an equivalent battery model, the various characteristic parameters of the battery can be calculated using the parameters to be estimated in the battery state equation, and then the maximum charge and discharge current of the battery can be solved. Among them, the commonly used battery models include the first-order RC equivalent battery model, the second-order RC equivalent battery model, the internal resistance equivalent battery model, the PNGV equivalent battery model and the GNL equivalent battery model, etc. Different equivalent battery models have a great influence on the accuracy of battery modeling. Among several models, the equivalent model containing RC has the highest accuracy, and the higher the RC order, the better the accuracy. Since internal resistance, concentration polarization reaction and electrochemical polarization reaction will be generated during the battery charging and discharging process, the second-order RC battery equivalent model is composed of an ohmic internal resistance and two RC circuits composed of capacitors and resistors in series, such as Figure 2 As shown, the two groups of capacitors and resistors are concentration polarization internal resistance, concentration polarization capacitance and electrochemical polarization internal resistance, electrochemical polarization capacitance. In this embodiment, the characteristic parameters of the battery are estimated by using the parameters to be estimated in the battery state equation, and the battery characteristic parameters such as open circuit voltage, ohmic internal resistance, concentration polarization internal resistance, concentration polarization capacitance, electrochemical polarization internal resistance and electrochemical polarization capacitance need to be estimated.

[0035] In this embodiment, the battery state equation can be obtained by establishing a second-order RC equivalent model. The second-order RC equivalent model can be converted into a differential equation through a series of transformations, and then, according to the corresponding relationship between the differential equation and the battery state equation, the corresponding relationship between the estimated parameter and the battery characteristic parameter is obtained.

[0036] 104. Obtain the maximum charge and discharge current of the battery to be estimated at the current moment according to the battery characteristic parameters at the current moment.

[0037] Specifically, the ohmic voltage drop, concentration polarization voltage drop and electrochemical polarization voltage drop of the battery have a certain corresponding relationship with the battery charge and discharge current, wherein the ohmic voltage drop can be calculated based on the battery charge and discharge current and the ohmic internal resistance, the electrochemical polarization voltage drop can be calculated based on the electrochemical polarization voltage drop and the battery charge and discharge current at the previous moment, and the concentration polarization voltage drop can be calculated based on the concentration polarization voltage drop and the battery charge and discharge current at the previous moment. And then, according to the relationship between the battery charge and discharge cut-off voltage being the difference between the open circuit voltage and the ohmic voltage drop, the concentration polarization voltage drop and the electrochemical polarization voltage drop, the relationship between the battery charge and discharge current and the charge and discharge cut-off voltage, the ohmic internal resistance, the electrochemical polarization internal resistance, the concentration polarization internal resistance, the electrochemical polarization capacitance, the concentration polarization capacitance, the electrochemical polarization voltage drop at the previous moment, the concentration polarization voltage drop at the previous moment and the open circuit voltage is further derived. Finally, the battery characteristic parameters at the current moment are brought into the relationship to calculate the maximum charge and discharge current at the current moment.

[0038] The method for estimating the maximum charge and discharge current of a battery provided in this embodiment first reads the voltage sequence value and the current sequence value of the battery to be estimated, then estimates the parameter to be estimated at the current moment by using the least squares method, and then obtains the corresponding relationship between the parameter to be estimated and the battery characteristic parameter according to the second-order RC equivalent battery model, thereby obtaining the battery characteristic parameter at the current moment through the corresponding relationship, and finally obtains the maximum charge and discharge current at the current moment according to the relationship between the battery characteristic parameter and the maximum charge and discharge current. The above method can accurately simulate the state of the battery through the second-order RC equivalent battery model, and the method combining the second-order RC equivalent battery model with the recursive least squares method can also accurately estimate the parameter to be estimated and the battery characteristic parameter, thereby improving the accuracy of the battery characteristic parameter estimation result, and also improving the accuracy of the battery maximum charge and discharge current estimation result.

[0039] Further, as a refinement and extension of the specific implementation of the above embodiment, in order to fully illustrate the implementation process of this embodiment, a method for estimating the maximum charge and discharge current of a battery is provided, such as Figure 3 As shown, the method comprises the following steps:

[0040] 201. Read the voltage sequence value and the current sequence value of the battery to be estimated.

[0041] 202. Obtain a voltage and current parameter matrix at a previous moment according to the voltage sequence value and the current sequence value of the battery to be estimated, and obtain a relative matrix at a previous moment, a parameter to be estimated at a previous moment, and a preset forgetting factor.

[0042] Specifically, first, a voltage and current sensor is used to read multiple groups of terminal voltage values ​​and current values ​​at consecutive moments, including the terminal voltage values ​​and current values ​​at moment k, moment k-1, and moment k-2, and then a voltage and current parameter matrix is ​​obtained based on the multiple groups of terminal voltage values ​​and current values. At the same time, a relative matrix of the previous moment and the parameters to be estimated at the previous moment are obtained from a database, wherein the relative matrix is ​​also composed of voltage values ​​and current values. Furthermore, a forgetting factor is preset to prevent the gain matrix from decaying sharply, so that the gain matrix can maintain a certain correction ability for the parameters to be estimated. Among them, the forgetting factor can be a value between 0 and 1.

[0043] 203. Obtain a gain matrix at the current moment according to the voltage and current parameter matrix at the previous moment, the relative matrix at the previous moment, and a preset forgetting factor.

[0044] 204. Obtain an estimated error value at the current moment according to a difference between a product of a transposed matrix of the voltage and current parameter matrix at the previous moment and the parameter to be estimated at the previous moment and a terminal voltage value at the current moment.

[0045] 205. According to the product of the gain matrix at the current moment and the estimated error value at the current moment, a recursive operation is performed on the parameter to be estimated at the previous moment to obtain the parameter to be estimated at the current moment.

[0046] Specifically, the gain matrix can be the ratio of the product of the relative matrix at the previous moment and the voltage and current parameter matrix at the previous moment, and the product of the relative matrix at the previous moment with the forgetting factor introduced, the voltage and current parameter matrix at the previous moment, and the transposed matrix of the voltage and current parameter matrix at the previous moment. In this embodiment, the new parameters are mainly corrected by the gain matrix, and a more accurate estimation result is obtained in combination with the estimation error.

[0047] In a specific embodiment, the gain matrix can be calculated by the following expression:

[0048]

[0049] Among them, G(k) is the gain matrix at time k, P(k-1) is the relative matrix at time k-1, is the voltage and current parameter matrix at time k-1, a is the forgetting factor, is the transposed matrix of the voltage and current parameter matrix at time k-1, and P(k-1) is the relative matrix at time k-1. In the above formula, P(k-1) and The data of the previous moment can be directly obtained from the database, and the forgetting factor a is a set value. Therefore, the above expression can be used to calculate the gain matrix based on the relative matrix of the previous moment and the voltage and current parameter matrix of the previous moment, and through the correction of the forgetting factor, and then the accuracy of the estimation result of the estimated parameter can be increased through the gain matrix.

[0050] Furthermore, the estimation error may be the difference between the terminal voltage value actually measured at the current moment and the terminal voltage calculated according to the parameter to be estimated at the previous moment and the voltage and current parameter matrix at the previous moment.

[0051] In a specific embodiment, the estimation error can be calculated according to the following expression:

[0052]

[0053] Among them, α(k) is the estimated error value at time k, V(k) is the terminal voltage value at time k, is the transposed matrix of the voltage and current parameter matrix at time k-1, and θ(k-1) is the parameter to be estimated at time k-1. In the above formula, V(k) is the data directly read, It can be calculated based on the voltage and current parameter values ​​at time k-1, and θ(k-1) can be obtained from the database, thereby calculating the estimated error value. The combination of the estimated error and the gain matrix can make the estimation result of the estimated parameter more accurate.

[0054] Further, according to the basic idea of ​​the recursive least square method, the parameter to be estimated at the current moment can be calculated based on the parameter to be estimated at the previous moment and the correction term. In this embodiment, the parameter to be estimated at the current moment can be the sum of the parameter to be estimated at the previous moment and the correction term. In addition, the parameter to be estimated at the current moment can also be the difference or product of the parameter to be estimated at the previous moment and the correction term, etc., which is not specifically limited in this application. In this embodiment, the correction term can be obtained based on the gain matrix and the estimation error, and can specifically be the product of the gain matrix and the estimation error.

[0055] In a specific embodiment, the parameter to be estimated at the current moment can be calculated according to the following expression:

[0056] θ(k)=θ(k-1)+G(k)α(k),

[0057] Among them, θ(k) is the parameter to be estimated at time k, θ(k-1) is the parameter to be estimated at time k-1, G(k) is the gain matrix at time k, and α(k) is the estimated error value at time k. In the above formula, θ(k-1) can be obtained from the database, G(k) and α(k) can be calculated according to the above expression, and the parameters to be estimated at the current moment can be obtained by substituting the known data into the above expression.

[0058] 206. Perform a recursive operation on the relative matrix at the previous moment according to the difference between the product of the transposed matrix of the voltage and current parameter matrix at the previous moment and the gain matrix at the current moment and the current value at the current moment to obtain the relative matrix at the current moment.

[0059] Among them, the relative matrix is ​​a matrix composed of voltage and current values. In this embodiment, the relative matrix will be used when calculating the gain matrix, that is, the relative matrix of the previous moment is required to calculate the gain matrix of the current moment, and the relative matrix of the current moment is required to calculate the gain matrix of the next moment. Therefore, it is necessary to perform a recursive operation on the relative matrix of the previous moment to obtain the relative matrix of the current moment, and store it in the database for use in calculating the gain matrix of the next moment. Among them, the relative matrix of the initial moment is the voltage and current matrix set at the beginning of the estimation process, and then through continuous recursion, the relative matrix of the current moment can be obtained.

[0060] Specifically, the relative matrix at the current moment can be calculated based on the difference between the current value at the current moment and the product of the gain matrix at the current moment and the voltage and current parameter matrix at the previous moment, and the relative matrix at the previous moment. In this embodiment, the relative matrix at the current moment can be the product of the difference between the current value at the current moment and the product of the gain matrix at the current moment and the voltage and current parameter matrix at the previous moment, and the relative matrix at the previous moment.

[0061] In a specific embodiment, the current relative matrix can be calculated according to the following expression:

[0062]

[0063] Among them, P(k) is the relative matrix at time k, I(k) is the current value at time k, G(k) is the gain matrix at time k, is the transposed matrix of the voltage and current parameter matrix at time k-1, and P(k-1) is the relative matrix at time k-1. In the above formula, I(k) is the data that can be directly measured, and G(k) can be calculated. It can be calculated based on the voltage and current values ​​at time k-1. P(k-1) can be directly obtained from the database, and then all known data are brought into the above expression to obtain the relative matrix at the current moment and store it in the database for use in estimating the parameters to be estimated at the next moment.

[0064] 207. Obtain a corresponding relationship between the parameter to be estimated and the battery characteristic parameter through a second-order RC equivalent battery model, and obtain the battery characteristic parameter at the current moment according to the corresponding relationship between the parameter to be estimated and the battery characteristic parameter.

[0065] Specifically, this step can be implemented in the following way: first, the equivalent expression of the second-order RC equivalent battery model is converted into a differential equation through Z function conversion, and then a second-order RC equivalent battery discrete time model is established to obtain a battery state equation, and finally, according to the correspondence between the differential equation and the battery state equation, the correspondence between the estimated parameters and the battery characteristic parameters is obtained.

[0066] Among them, the Z function conversion is to convert the discrete mathematical model into a differential equation or an algebraic equation to facilitate calculation.

[0067] Specifically, since the battery will produce internal resistance and polarization reaction during the charge and discharge process, wherein the polarization reaction includes electrochemical polarization and concentration polarization, therefore, the second-order RC equivalent battery model is established in this embodiment, and the equivalent expression obtained is that the battery terminal voltage is the sum of the open circuit voltage, the ohmic voltage drop, the electrochemical polarization voltage and the concentration polarization voltage. Further, the concentration polarization voltage and the electrochemical polarization voltage can be discretized to obtain the relationship between the concentration polarization voltage and the concentration polarization resistance, the concentration polarization capacitance, and the output current value at the previous moment, and the relationship between the electrochemical polarization voltage and the electrochemical polarization resistance, the electrochemical polarization capacitance, and the output current value at the previous moment. Then, the discretized second-order RC equivalent battery model can be converted into a differential equation according to the Z function conversion.

[0068] In a specific embodiment, the equivalent expression of the second-order RC equivalent battery model is:

[0069] V=Voc+I B R Ω +Vs+Vm,

[0070] Where V is the terminal voltage, Voc is the open circuit voltage, I B is the current value, R Ω is the ohmic internal resistance, Vs is the concentration polarization voltage, and Vm is the electrochemical polarization voltage;

[0071] The expression of the discrete concentration polarization voltage is:

[0072] Vs(k)=e -△t / RsCs Vs(k-1)+I B (k-1)Rs(1-e -△t / RsCs ),

[0073] Where Vs(k) is the concentration polarization voltage of the battery at time k, e is a constant, △t is the sampling period of the voltage sequence value and the current sequence value, Vs(k-1) is the concentration polarization voltage of the battery at time k-1, I B (k-1) is the current value at time k-1, Rs is the concentration polarization internal resistance, and Cs is the concentration polarization capacitance.

[0074] The expression of the discretized electrochemical polarization voltage is:

[0075] Vm(k)=e -△t / RmCm Vm(k-1)+I B (k-1)Rm(1-e -△t / RmCm ),

[0076] Wherein, Vm(k) is the electrochemical polarization voltage of the battery at time k, Vm(k-1) is the electrochemical polarization voltage of the battery at time k-1, Rm is the electrochemical polarization internal resistance, and Cm is the electrochemical polarization capacitance.

[0077] Introducing the first intermediate parameter, the second intermediate parameter, the third intermediate parameter and the fourth intermediate parameter a1, b1, a2, b2,

[0078] a1=e -△t / RsCs , b1=Rs(1-e -△t / RsCs ), a2=e -△t / RmCm , b2=Rm(1-e -△t / RmCm );

[0079] Then Vs(k)=a1Vs(k-1)+b1I B (k-1), Vm(k)=a2Vm(k-1)+b2I B (k-1).

[0080] According to the Z function conversion, the discretized second-order RC equivalent battery model is converted into a differential equation, which is expressed as follows:

[0081] V(k)=(a1+a2)V(k-1)-a1a2V(k-2)+R Ω I(k)+[b1-b2-RΩ(a1+a2)]I(k-1)

[0082] +(a1a2RΩ-b1a2-b2a1)I(k-2)+[1-(a1+a2)+a1a2]Voc,

[0083] Wherein, V(k) is the terminal voltage of the battery to be estimated at time k, a1, b1, a2, b2 are the first intermediate parameter, the second intermediate parameter, the third intermediate parameter and the fourth intermediate parameter respectively, e is a constant, △t is the sampling period of the voltage sequence value and the current sequence value, Voc is the open circuit voltage, R Ω is the ohmic internal resistance, Rs is the concentration polarization internal resistance, Rm is the electrochemical polarization internal resistance, Cs is the concentration polarization capacitance, and Cm is the electrochemical polarization capacitance.

[0084] Through the above relationship, the differential equation of the second-order RC equivalent battery model can be obtained.

[0085] Further, the second-order RC equivalent battery discrete time model is an expression of the second-order RC equivalent model formed according to discrete time, and the equation expression can be the relationship between the terminal voltage, the parameter to be estimated and the voltage and current parameter matrix. Among them, the parameter to be estimated can include multiple parameter vectors. It is known to those skilled in the art that the more the number of parameter vectors, the more accurate the estimation of the parameter to be estimated. In this embodiment, the parameter to be estimated can include six parameter vectors, namely the first parameter vector, the second parameter vector, the third parameter vector, the fourth parameter vector, the fifth parameter vector and the sixth parameter vector. In other embodiments, the number of parameter vectors of the parameter to be estimated may not be limited to this. According to the number of parameters to be estimated, the corresponding number of voltage and current values ​​can be read to form a voltage and current parameter matrix. Among them, the voltage and current parameter matrix can also be composed of voltage and current values ​​at six different times, corresponding to the six parameter vectors of the parameter to be estimated.

[0086] Specifically, the battery state equation of the second-order RC equivalent battery discrete time model is that the terminal voltage value is the product of the parameter to be estimated and the voltage and current parameter matrix. Substituting multiple parameter vectors into the battery state equation, the equation relationship between the terminal voltage and multiple parameter vectors and multiple voltage and current values ​​is obtained. Furthermore, the differential equation and the battery state equation are both equations about the terminal voltage. According to the corresponding relationship between them, the corresponding relationship between the parameter to be estimated and the battery characteristic parameter is obtained.

[0087] In a specific embodiment, the expression of the battery state equation is:

[0088]

[0089]

[0090] Wherein, V(k) is the terminal voltage of the battery to be estimated at time k, θ is the parameter to be estimated, θ1, θ2, θ3, θ4, θ5, θ6 are the first parameter vector, the second parameter vector, the third parameter vector, the fourth parameter vector, the fifth parameter vector and the sixth parameter vector of the parameter to be estimated respectively, θ k is the transposed matrix of the parameters to be estimated, is the voltage and current parameter matrix, V(k-1) is the terminal voltage of the battery to be estimated at time k-1, V(k-2) is the terminal voltage of the battery to be estimated at time k-2, I(k) is the current value of the battery to be estimated at time k, I(k-1) is the current value of the battery to be estimated at time k-1, and I(k-2) is the current value of the battery to be estimated at time k-2.

[0091] Furthermore, according to the corresponding relationship between the difference equation and the battery state equation, we can get:

[0092] a1+a2=θ1, -a1a2=θ2, RΩ=θ3, b1-b2-RΩ(a1+a2)=θ4,

[0093] a1a2RΩ-b1a2-b2a1=θ5, [1-(a1+a2)+a1a2]Voc=θ6, Voc=θ6 / (1-θ1-θ2),

[0094] a1=e -△t / RsCs , b1=Rs(1-e -△t / RsCs ), a2=e -△t / RmCm , b2=Rm(1-e -△t / RmCm ),

[0095] Among them, θ1, θ2, θ3, θ4, θ5, θ6 are the first parameter vector, second parameter vector, third parameter vector, fourth parameter vector, fifth parameter vector and sixth parameter vector of the parameters to be estimated, respectively; a1, b1, a2, b2 are the first intermediate parameter, the second intermediate parameter, the third intermediate parameter and the fourth intermediate parameter, respectively; e is a constant, △t is the sampling period of the voltage sequence value and the current sequence value, Voc is the open circuit voltage, RΩ is the ohmic internal resistance, Rs is the concentration polarization internal resistance, Rm is the electrochemical polarization internal resistance, Cs is the concentration polarization capacitance, and Cm is the electrochemical polarization capacitance.

[0096] Furthermore, through the correspondence between the differential equation and the battery state equation, the relationship between the parameters to be estimated and the battery characteristic parameters can be obtained.

[0097] 208. Obtain the maximum charge and discharge current of the battery to be estimated at the current moment according to the battery characteristic parameters at the current moment.

[0098] Specifically, this step may include the following method: first, according to the equation relationship between the sum of the open circuit voltage, the ohmic voltage drop, the electrochemical polarization voltage drop, the concentration polarization voltage drop value and the charge and discharge cut-off voltage, the relationship between the maximum charge and discharge current of the battery and the battery characteristic parameters is obtained, and then the battery characteristic parameters at the current moment are input into the relationship between the maximum charge and discharge current of the battery and the battery characteristic parameters to obtain the maximum charge and discharge current of the battery to be estimated at the current moment.

[0099] The charge and discharge cut-off voltage is determined by the characteristics of the lithium battery. For example, the discharge cut-off voltage may be 3.2V to 3.5V, and the charge cut-off voltage may be 4.1V to 4.3V.

[0100] Specifically, the battery charge and discharge cut-off voltage is the difference between the open circuit voltage and the ohmic voltage drop, electrochemical polarization voltage drop, and concentration polarization voltage drop. Among them, the ohmic voltage drop can be the product of the battery charge and discharge current and the battery ohmic internal resistance; the electrochemical polarization voltage drop can be the product of the electrochemical polarization voltage drop at the previous moment and the battery charge and discharge current; the concentration polarization voltage drop can be the product of the concentration polarization voltage drop at the previous moment and the battery charge and discharge current, and then the equation relationship between the battery charge and discharge current and the battery characteristic parameters can be obtained. Furthermore, the parameters to be estimated at the current moment can be used to obtain the battery characteristic parameters at the current moment, and then the maximum charge and discharge current of the current battery can be obtained.

[0101] In a specific embodiment, the equation relationship between the charge and discharge cut-off voltage and the open circuit voltage, ohmic voltage drop, electrochemical polarization voltage drop, and concentration polarization voltage drop is:

[0102] Vt(k)=Voc(k)–Vr(k)-Vs(k)-Vm(k),

[0103] Among them, Vt(k) is the battery charge and discharge cut-off voltage, Voc(k) is the open circuit voltage, Vr(k) is the battery's ohmic voltage drop, Vs(k) is the electrochemical polarization voltage drop, and Vm(k) is the concentration polarization voltage drop.

[0104] The relationship between ohmic voltage drop, electrochemical polarization voltage drop, concentration polarization voltage drop and battery charge and discharge current is:

[0105] Vr(k)=I B R Ω ;

[0106] Vs(k)=I B Rs(1-e -k / RsCs )-Vs(k-1)e -k / RsCs ;

[0107] Vm(k)=I B Rm(1-e -k / RmCm )-Vm(k-1)e -k / RmCm ,

[0108] Furthermore, the relationship between the charge and discharge cut-off voltage and the battery characteristic parameters is:

[0109] Vt(t)=Voc(t)-I B R Ω –(I B Rs(1-e -k / RsCs )-Vs(k-1)e -k / RsCs )–(I B Rm(1-e -k / RmCm )-Vm(k-1)e -k / RmCm ),

[0110] Furthermore, the relationship between the maximum charge and discharge current and the battery characteristic parameters is:

[0111] I B max(k)=(Voc(k)+Vs(k-1)e -k / RsCs +Vm(k-1)e -k / RmCm -Vt(k)) / (R Ω +Rs(1-e -k / RsCs )+Rm(1-e -k / RmCm )),

[0112] Among them, I B max(k) is the maximum charge and discharge current at time k, e is a constant, k is the sampling time of the voltage sequence value and the current sequence value, Voc(k) is the open circuit voltage at time k, Vs(k-1) is the concentration polarization voltage drop at time k-1, Vm(k-1) is the electrochemical polarization voltage drop at time k-1, Vt(k) is the charge and discharge cut-off voltage at time k, R Ω is the ohmic internal resistance, Rs is the concentration polarization internal resistance, Rm is the electrochemical polarization internal resistance, Cs is the concentration polarization capacitance, and Cm is the electrochemical polarization capacitance. Further, the battery characteristic parameters calculated according to the estimated parameters are substituted into the relationship to obtain the maximum charge and discharge current of the battery at the current moment.

[0113] 209. Obtain a correction factor of the battery to be estimated, and obtain a correction coefficient of the battery to be estimated according to the correction factor of the battery to be estimated.

[0114] 210. Obtain a maximum charge and discharge current correction value of the battery to be estimated at the current moment according to the product of the maximum charge and discharge current of the battery to be estimated at the current moment and the correction coefficient of the battery to be estimated.

[0115] Specifically, the correction factor of the battery to be estimated may include the current temperature value, the lowest voltage value, the highest voltage value, functional failure information, safety failure information, etc. The correction factor may be one of them or a combination of multiple ones, which is not limited in this application. Moreover, according to the correction factor, the correction coefficient of the battery to be estimated can be obtained. The correction coefficient can be a value between 0-1, and the correction coefficient can change with the change of the correction factor. Furthermore, according to the product between the maximum charge and discharge current of the estimated battery at the current moment and the correction coefficient of the battery to be estimated, the maximum charge and discharge current correction value of the battery to be estimated at the current moment can be obtained.

[0116] In one embodiment, the correction factor of the battery is the battery temperature. When the battery temperature is between 0°C and 40°C, the correction factor is 1. When the battery temperature is outside this range, as the temperature rises or falls, the correction factor gradually decreases to 0. The maximum charge and discharge current correction value of the battery to be estimated at the current moment can be obtained by multiplying the maximum charge and discharge current of the battery to be estimated at the current moment by the temperature correction factor.

[0117] In one embodiment, the correction factor of the battery is the minimum voltage value of the battery. When the minimum voltage of the battery is in the range of 3.7V-4.2V, the correction factor is 1. As the voltage decreases, the correction factor gradually decreases to 0. The maximum charge and discharge current correction value of the battery to be estimated at the current moment can be obtained by multiplying the maximum charge and discharge current of the battery at the current moment by the minimum voltage correction factor.

[0118] In one embodiment, the correction factor of the battery is the maximum voltage value of the battery. When the maximum voltage of the battery is in the range of 3.2V-3.7V, the correction factor is 1. As the voltage increases, the correction factor gradually decreases to 0. The maximum charge and discharge current correction value of the battery to be estimated at the current moment can be obtained by multiplying the maximum charge and discharge current of the battery at the current moment by the maximum voltage correction factor.

[0119] In one embodiment, the correction factor of the battery is functional fault information, wherein the battery fault information may include multiple levels, each level corresponding to a correction coefficient, for example, the first-level fault correction coefficient may be 0.7, the second-level fault correction coefficient may be 0.5, and the third-level fault correction coefficient may be 0. According to the product of the estimated maximum charge and discharge current of the battery at the current moment and the battery fault information correction coefficient, the maximum charge and discharge current correction value of the battery to be estimated at the current moment may be obtained.

[0120] In one embodiment, the correction factor of the battery is safety fault information, wherein the safety fault information may include multiple levels, each level corresponding to a correction factor, for example, when the battery system fails and the vehicle speed is greater than 20km / h, the correction factor is 0.5; when the battery system fails and the vehicle speed is less than 20km / h, the correction factor is 0; when the battery system has a short circuit, short circuit or collision safety fault, the correction factor is 0.7. According to the product between the estimated maximum charge and discharge current of the battery at the current moment and the safety fault information correction factor, the maximum charge and discharge current correction value of the battery to be estimated at the current moment can be obtained.

[0121] 211. Detect the charging and discharging mode of the battery to be estimated.

[0122] 212. When the battery to be estimated is in the discharge mode, the maximum charging current of the charging pile is set to 0A, and the maximum discharge current of the charging pile is obtained according to the maximum charge and discharge current of the battery to be estimated at the current moment.

[0123] 213. When the battery to be estimated is in charging mode, the maximum discharge current of the battery to be estimated is set to 0 A, and the maximum charging current and maximum braking energy recovery current of the charging pile are set according to the maximum charge and discharge current of the battery to be estimated at the current moment.

[0124] Among them, the battery charging and discharging mode refers to the battery being in charging mode or discharging mode; the charging pile is a device for charging electric vehicle batteries; the maximum braking energy recovery current is the current generated when the kinetic energy of the vehicle is converted into electrical energy during deceleration or braking.

[0125] Specifically, the current charging and discharging mode of the battery to be estimated is first detected. When the battery to be estimated is in the discharging mode, the maximum charging current of the charging pile is limited to 0A, and the maximum discharge current of the charging pile can be obtained according to the maximum charging and discharging current of the battery to be estimated at the current moment; when the battery to be estimated is in the charging mode, the discharge current of the battery is limited to 0A, and the maximum charging current and the maximum braking energy recovery current of the charging pile can be obtained according to the estimated maximum charging and discharging current value of the battery.

[0126] During the actual use of the battery of an electric vehicle, the battery temperature, voltage value, battery functional failure, battery safety failure, and battery charge and discharge mode will affect the battery life. Therefore, while improving the accuracy of estimating the maximum charge and discharge current of the battery, the influence of factors such as the battery temperature, voltage value, battery functional failure, battery safety failure, and battery charge and discharge mode on the maximum charge and discharge current of the battery should also be considered, thereby improving the battery life. The method for estimating the maximum charge and discharge current of a battery provided in this embodiment sets a correction coefficient related to temperature, voltage, etc., and corrects the maximum charge and discharge current of the battery by the correction coefficient. The obtained maximum charge and discharge current correction value can take into account the influence of factors such as the battery temperature, voltage value, battery functional failure, battery safety failure, and battery charge and discharge mode on the battery on the basis of accurately estimating the maximum charge and discharge current, thereby improving the battery life.

[0127] Further, in order to specifically illustrate the method for estimating the maximum charge and discharge current of a battery described in the above embodiments, this embodiment provides a flow chart of a method for estimating the maximum charge and discharge current of a battery, as shown in FIG. Figure 4 shown.

[0128] Specifically, the data is first initialized, and multiple groups of voltage and current values ​​at consecutive moments, parameters to be estimated at the previous moment, relative matrices at the previous moment, and battery temperatures are obtained from the database. Then, the voltage and current parameter matrix is ​​calculated based on the read voltage and current values, and then the gain matrix and the estimation error are calculated in turn. The parameters to be estimated at the current moment and the relative matrix at the current moment are calculated using the recursive least squares method based on the gain matrix, the estimation error, and the parameters to be estimated at the previous moment, and stored in the database. Then, the battery characteristic parameters of the battery are obtained based on the parameters to be estimated at the current moment. Further, the open circuit voltage value in the battery characteristic parameters is obtained. If the open circuit voltage value is lower than a certain value, a parking charge instruction is issued; if the open circuit voltage value is higher than a certain value, the current maximum charge and discharge current value of the battery is continued to be estimated. The method provided in this embodiment can monitor the battery characteristic parameters and the maximum charge and discharge current of the battery in real time, and indicate to the user whether it is necessary to stop and charge based on the battery characteristic parameters and the maximum charge and discharge current. In this way, the accuracy and real-time performance of the maximum charge and discharge current estimation of the battery can be improved, thereby improving the service life of the battery.

[0129] Further, as Figures 1 to 4 The specific implementation of the method shown in the embodiment provides a device for estimating the maximum charge and discharge current of a battery, such as Figure 5 As shown, the device includes: a data acquisition module 31, a parameter estimation module 32, a battery characteristic parameter estimation module 33 and a maximum charge and discharge current estimation module 34.

[0130] The data acquisition module 31 can be used to read the voltage sequence value and the current sequence value of the battery to be estimated, wherein the voltage sequence value includes the terminal voltage values ​​at multiple consecutive moments, and the current sequence value includes the current values ​​at multiple consecutive moments;

[0131] The estimated parameter estimation module 32 can be used to obtain the estimated parameter at the current moment according to the voltage sequence value and the current sequence value of the battery to be estimated by using the recursive least square method;

[0132] The battery characteristic parameter estimation module 33 can be used to obtain the corresponding relationship between the parameter to be estimated and the battery characteristic parameter through the second-order RC equivalent battery model, and obtain the battery characteristic parameter at the current moment according to the corresponding relationship between the parameter to be estimated and the battery characteristic parameter.

[0133] The maximum charge and discharge current estimation module 34 can be used to obtain the maximum charge and discharge current of the battery to be estimated at the current moment according to the battery characteristic parameters at the current moment.

[0134] In a specific application scenario, the estimated parameter estimation module 32 can be specifically used to obtain the voltage and current parameter matrix of the previous moment according to the voltage sequence value and current sequence value of the battery to be estimated, and obtain the relative matrix of the previous moment, the parameters to be estimated at the previous moment and the preset forgetting factor; obtain the gain matrix of the current moment according to the voltage and current parameter matrix of the previous moment, the relative matrix of the previous moment and the preset forgetting factor; obtain the estimated error value of the current moment according to the product of the transposed matrix of the voltage and current parameter matrix of the previous moment and the parameters to be estimated at the previous moment and the difference between the terminal voltage value of the current moment; perform a recursive operation on the parameters to be estimated at the previous moment according to the product between the gain matrix of the current moment and the estimated error value of the current moment to obtain the parameters to be estimated at the current moment.

[0135] In a specific application scenario, the estimated parameter estimation module 32 can also be used to perform recursive operation on the relative matrix at the previous moment based on the difference between the product of the transposed matrix of the voltage and current parameter matrix at the previous moment and the gain matrix at the current moment, to obtain the relative matrix at the current moment.

[0136] In a specific application scenario, the battery characteristic parameter estimation module 33 can be specifically used to convert the equivalent expression of the second-order RC equivalent battery model into a differential equation through Z function conversion; establish a second-order RC equivalent battery discrete time model to obtain a battery state equation; according to the correspondence between the differential equation and the battery state equation, obtain the correspondence between the parameters to be estimated and the battery characteristic parameters; wherein the parameters to be estimated include a first parameter vector, a second parameter vector, a third parameter vector, a fourth parameter vector, a fifth parameter vector and a sixth parameter vector; the battery characteristic parameters include open circuit voltage, ohmic internal resistance, concentration polarization internal resistance, concentration polarization capacitance, electrochemical polarization internal resistance and electrochemical polarization capacitance.

[0137] In a specific application scenario, the maximum charge and discharge current estimation module 34 can be specifically used to obtain the relationship between the maximum charge and discharge current of the battery and the battery characteristic parameters based on the equation relationship between the sum of the open circuit voltage, ohmic voltage drop, electrochemical polarization voltage drop, concentration polarization voltage drop value and the charge and discharge cut-off voltage; the battery characteristic parameters at the current moment are input into the relationship between the maximum charge and discharge current of the battery and the battery characteristic parameters to obtain the maximum charge and discharge current of the battery to be estimated at the current moment.

[0138] In a specific application scenario, the maximum charge and discharge current estimation module 34 can also be used to obtain a correction factor of the battery to be estimated, wherein the correction factor includes one or more of the current temperature value, the lowest voltage value, the highest voltage value, functional fault information and safety fault information; according to the correction factor of the battery to be estimated, a correction coefficient of the battery to be estimated is obtained, wherein the correction coefficient includes one or more of the temperature correction coefficient, the low voltage correction coefficient, the high voltage correction coefficient, the functional fault correction coefficient and the functional fault correction coefficient; according to the product between the maximum charge and discharge current of the battery to be estimated at the current moment and the correction coefficient of the battery to be estimated, the maximum charge and discharge current correction value of the battery to be estimated at the current moment is obtained.

[0139] In a specific application scenario, the maximum charge and discharge current estimation module 34 can also be used to detect the charge and discharge mode of the battery to be estimated; when the battery to be estimated is in the discharge mode, the maximum charge current of the charging pile is set to 0A, and the maximum discharge current of the battery to be estimated is set according to the maximum charge and discharge current of the battery to be estimated at the current moment; when the battery to be estimated is in the charging mode, the maximum discharge current of the battery to be estimated is set to 0A, and the maximum charge current and maximum braking energy recovery current of the charging pile are set according to the maximum charge and discharge current of the battery to be estimated at the current moment.

[0140] It should be noted that for other corresponding descriptions of the functional units involved in the device for estimating the maximum charge and discharge current of a battery provided in this embodiment, reference can be made to Figures 1 to 4 The corresponding description in will not be repeated here.

[0141] Based on the above Figures 1 to 4 The method shown in the embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the above-mentioned Figures 1 to 4 The method for estimating the maximum charge and discharge current of the battery is shown.

[0142] Based on this understanding, the technical solution of the present application can be embodied in the form of a software product. The software product to be identified can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each implementation scenario of the present application.

[0143] Based on the above Figures 1 to 4 The maximum battery charge and discharge current estimation method shown, and Figure 5The embodiment of the battery maximum charge and discharge current estimation device shown in the figure, in order to achieve the above purpose, this embodiment also provides a physical device for estimating the battery maximum charge and discharge current, which can be a personal computer, a server, a smart phone, a tablet computer, a smart watch, or other network devices, etc. The physical device includes a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to achieve the above Figures 1 to 4 The method shown.

[0144] Optionally, the physical device may also include a user interface, a network interface, a camera, a radio frequency (RF) circuit, a sensor, an audio circuit, a WI-FI module, etc. The user interface may include a display, an input unit such as a keyboard, etc., and the optional user interface may also include a USB interface, a card reader interface, etc. The network interface may optionally include a standard wired interface, a wireless interface (such as a WI-FI interface), etc.

[0145] Those skilled in the art will appreciate that the physical device structure for estimating the maximum charge and discharge current of a battery provided in this embodiment does not constitute a limitation on the physical device, and may include more or fewer components, or a combination of certain components, or different arrangements of components.

[0146] The storage medium may also include an operating system and a network communication module. The operating system is a program that manages the hardware of the physical device and the software resources to be identified, and supports the operation of the information processing program and other software and / or programs to be identified. The network communication module is used to realize the communication between the components inside the storage medium, and the communication with other hardware and software in the information processing physical device.

[0147] Through the description of the above implementation methods, the technical personnel in this field can clearly understand that the present application can be implemented by means of software plus the necessary general hardware platform, or by hardware. By applying the technical solution of the present application, the voltage sequence value and the current sequence value of the battery to be estimated are first read, wherein the voltage sequence value includes the terminal voltage value at multiple consecutive moments, and the current sequence value includes the current value at multiple consecutive moments; then, the recursive least squares method is used to obtain the parameters to be estimated at the current moment according to the voltage sequence value and the current sequence value of the battery to be estimated; then, the corresponding relationship between the parameters to be estimated and the battery characteristic parameters is obtained through the second-order RC equivalent battery model, and the battery characteristic parameters at the current moment are obtained according to the corresponding relationship between the parameters to be estimated and the battery characteristic parameters; finally, according to the battery characteristic parameters at the current moment, the maximum charge and discharge current of the battery to be estimated at the current moment is obtained. Compared with the prior art, the technical solution of the present application improves the accuracy of the estimation result of the maximum charge and discharge current of the battery.

[0148] Those skilled in the art will appreciate that the accompanying drawings are only schematic diagrams of a preferred implementation scenario, and the modules or processes in the accompanying drawings are not necessarily necessary for implementing the present application. Those skilled in the art will appreciate that the modules in the devices in the implementation scenario can be distributed in the devices of the implementation scenario according to the description of the implementation scenario, or can be changed accordingly and located in one or more devices different from the present implementation scenario. The modules of the above-mentioned implementation scenario can be combined into one module, or can be further split into multiple submodules.

[0149] The above serial numbers of this application are only for description and do not represent the advantages and disadvantages of the implementation scenarios. The above disclosure is only a few specific implementation scenarios of this application, but this application is not limited to them, and any changes that can be thought of by technicians in this field should fall within the scope of protection of this application.

Claims

1. A method for estimating the maximum charge and discharge current of a battery, characterized in that: The method comprises: Reading a voltage sequence value and a current sequence value of the battery to be estimated, wherein the voltage sequence value includes terminal voltage values ​​at multiple consecutive moments, and the current sequence value includes current values ​​at multiple consecutive moments; Using the recursive least square method, the parameters to be estimated at the current moment are obtained according to the voltage sequence value and the current sequence value of the battery to be estimated, including: According to the voltage sequence value and current sequence value of the battery to be estimated, a voltage and current parameter matrix of the previous moment is obtained, and a relative matrix of the previous moment, a parameter to be estimated at the previous moment and a preset forgetting factor are obtained; Obtaining a gain matrix at the current moment according to the voltage and current parameter matrix at the previous moment, the relative matrix at the previous moment, and a preset forgetting factor; Obtaining an estimated error value at the current moment according to a difference between a product of a transposed matrix of the voltage and current parameter matrix at the previous moment and the parameter to be estimated at the previous moment and a terminal voltage value at the current moment; According to the product between the gain matrix at the current moment and the estimated error value at the current moment, a recursive operation is performed on the parameter to be estimated at the previous moment to obtain the parameter to be estimated at the current moment; According to the difference between the product of the transposed matrix of the voltage and current parameter matrix at the previous moment and the gain matrix at the current moment and the current value at the current moment, a recursive operation is performed on the relative matrix at the previous moment to obtain the relative matrix at the current moment; The corresponding relationship between the estimated parameter and the battery characteristic parameter is obtained through the second-order RC equivalent battery model, and the battery characteristic parameter at the current moment is obtained according to the corresponding relationship between the estimated parameter and the battery characteristic parameter, including: The equivalent expression of the second-order RC equivalent battery model is converted into a differential equation through Z function conversion; A second-order RC equivalent battery discrete-time model is established to obtain the battery state equation; According to the corresponding relationship between the differential equation and the battery state equation, a corresponding relationship between the parameter to be estimated and the battery characteristic parameter is obtained; Wherein, the parameters to be estimated include a first parameter vector, a second parameter vector, a third parameter vector, a fourth parameter vector, a fifth parameter vector and a sixth parameter vector; the battery characteristic parameters include open circuit voltage, ohmic internal resistance, concentration polarization internal resistance, concentration polarization capacitance, electrochemical polarization internal resistance and electrochemical polarization capacitance; Obtaining the maximum charge and discharge current of the battery to be estimated at the current moment according to the battery characteristic parameters at the current moment, including: According to the equation relationship between the sum of the open circuit voltage, ohmic voltage drop, electrochemical polarization voltage drop, concentration polarization voltage drop and the charge and discharge cut-off voltage, the relationship between the maximum charge and discharge current of the battery and the battery characteristic parameters is obtained; The battery characteristic parameter at the current moment is input into the relationship between the maximum charge and discharge current of the battery and the battery characteristic parameter to obtain the maximum charge and discharge current of the battery to be estimated at the current moment.

2. The method according to claim 1, characterized in that The method further comprises: Obtaining a correction factor of the battery to be estimated, wherein the correction factor includes one or more of a current temperature value, a minimum voltage value, a maximum voltage value, functional failure information, and safety failure information; Obtaining a correction coefficient of the battery to be estimated according to the correction factor of the battery to be estimated, wherein the correction coefficient includes one or more of a temperature correction coefficient, a low voltage correction coefficient, a high voltage correction coefficient, a functional failure correction coefficient, and a functional failure correction coefficient; The maximum charge and discharge current correction value of the battery to be estimated at the current moment is obtained according to the product of the maximum charge and discharge current of the battery to be estimated at the current moment and the correction coefficient of the battery to be estimated.

3. The method according to claim 1, characterized in that: The method further comprises: Detecting the charging and discharging mode of the battery to be estimated; When the battery to be estimated is in the discharge mode, the maximum charging current of the charging pile is set to 0A, and the maximum discharge current of the battery to be estimated is set according to the maximum charge and discharge current of the battery to be estimated at the current moment; When the battery to be estimated is in charging mode, the maximum discharge current of the battery to be estimated is set to 0A, and the maximum charging current and maximum braking energy recovery current of the charging pile are set according to the maximum charge and discharge current of the battery to be estimated at the current moment.

4. A device for estimating the maximum charge and discharge current of a battery, characterized in that: The device comprises: A data acquisition module, used to read the voltage sequence value and the current sequence value of the battery to be estimated, wherein the voltage sequence value includes the terminal voltage values ​​at multiple consecutive moments, and the current sequence value includes the current values ​​at multiple consecutive moments; The estimated parameter estimation module is used to obtain the estimated parameter at the current moment according to the voltage sequence value and current sequence value of the battery to be estimated by using the recursive least square method, including: According to the voltage sequence value and current sequence value of the battery to be estimated, a voltage and current parameter matrix of the previous moment is obtained, and a relative matrix of the previous moment, a parameter to be estimated at the previous moment and a preset forgetting factor are obtained; Obtaining a gain matrix at the current moment according to the voltage and current parameter matrix at the previous moment, the relative matrix at the previous moment, and a preset forgetting factor; Obtaining an estimated error value at the current moment according to a difference between a product of a transposed matrix of the voltage and current parameter matrix at the previous moment and the parameter to be estimated at the previous moment and a terminal voltage value at the current moment; According to the product between the gain matrix at the current moment and the estimated error value at the current moment, a recursive operation is performed on the parameter to be estimated at the previous moment to obtain the parameter to be estimated at the current moment; According to the difference between the product of the transposed matrix of the voltage and current parameter matrix at the previous moment and the gain matrix at the current moment and the current value at the current moment, a recursive operation is performed on the relative matrix at the previous moment to obtain the relative matrix at the current moment; The battery characteristic parameter estimation module is used to obtain the corresponding relationship between the parameter to be estimated and the battery characteristic parameter through the second-order RC equivalent battery model, and obtain the battery characteristic parameter at the current moment according to the corresponding relationship between the parameter to be estimated and the battery characteristic parameter, including: The equivalent expression of the second-order RC equivalent battery model is converted into a differential equation through Z function conversion; A second-order RC equivalent battery discrete-time model is established to obtain the battery state equation; According to the corresponding relationship between the differential equation and the battery state equation, a corresponding relationship between the parameter to be estimated and the battery characteristic parameter is obtained; Wherein, the parameters to be estimated include a first parameter vector, a second parameter vector, a third parameter vector, a fourth parameter vector, a fifth parameter vector and a sixth parameter vector; the battery characteristic parameters include open circuit voltage, ohmic internal resistance, concentration polarization internal resistance, concentration polarization capacitance, electrochemical polarization internal resistance and electrochemical polarization capacitance; The maximum charge and discharge current estimation module is used to obtain the maximum charge and discharge current of the battery to be estimated at the current moment according to the battery characteristic parameters at the current moment, including: According to the equation relationship between the sum of the open circuit voltage, ohmic voltage drop, electrochemical polarization voltage drop, concentration polarization voltage drop and the charge and discharge cut-off voltage, the relationship between the maximum charge and discharge current of the battery and the battery characteristic parameters is obtained; The battery characteristic parameter at the current moment is input into the relationship between the maximum charge and discharge current of the battery and the battery characteristic parameter to obtain the maximum charge and discharge current of the battery to be estimated at the current moment.

5. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 3 are implemented.

6. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 3 are implemented.

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