阅读说明：本技术 一种单体电池的模型参数计算方法、装置和介质 (Method, device and medium for calculating model parameters of single battery ) 是由 李展 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种单体电池的模型参数计算方法、装置和介质,所述单体电池的模型参数计算方法包括：根据电池模组的平均等效模型,计算所述电池模组的平均模型参数组；构建所述电池模组的单体电池等效模型；根据所述平均模型参数组和所述电池模组的单体电池等效模型的离散化方程,计算所述电池模组中每一单体电池的模型参数组。采用本发明实施例,能准确地计算电池模组中每一单体电池的模型参数,有效提高了计算单体电池的模型参数的效率。(The invention discloses a method, a device and a medium for calculating model parameters of a single battery, wherein the method for calculating the model parameters of the single battery comprises the following steps: calculating an average model parameter group of the battery module according to an average equivalent model of the battery module; constructing a single battery equivalent model of the battery module; and calculating the model parameter group of each single battery in the battery module according to the average model parameter group and the discretization equation of the equivalent model of the single battery of the battery module. By adopting the embodiment of the invention, the model parameter of each single battery in the battery module can be accurately calculated, and the efficiency of calculating the model parameter of each single battery is effectively improved.)

1. A method for calculating model parameters of a single battery is characterized by comprising the following steps:

calculating an average model parameter group of the battery module according to an average equivalent model of the battery module;

and calculating the model parameter group of each single battery in the battery module according to the average model parameter group and the discretization equation of the equivalent model of the single battery of the battery module.

2. The method of calculating model parameters of a unit cell according to claim 1, wherein the average model parameter group includes an average ohmic internal resistance, an average electric polarization capacitance, an average concentration polarization internal resistance, and an average concentration polarization capacitance; the model parameter set comprises ohmic internal resistance, electric polarization capacitance, concentration polarization internal resistance and concentration polarization capacitance of each single battery.

3. The method according to claim 2, wherein the calculating the model parameter set of each cell according to the discretization equation of the average model parameter set and the cell equivalent model specifically comprises:

calculating the dynamic voltage of each single battery;

estimating the ohmic internal resistance of each single battery according to the average ohmic internal resistance and the dynamic voltage of the single battery;

calculating the electric polarization voltage and the concentration polarization voltage of each single battery;

calculating the electric polarization internal resistance and the electric polarization capacitance of each single battery according to the electric polarization voltage, the average electric polarization internal resistance, the average electric polarization capacitance and the discretization equation of the single battery equivalent model of each single battery;

and calculating the concentration polarization internal resistance and the concentration polarization capacitance of each single battery according to the concentration polarization voltage, the average concentration polarization internal resistance, the average concentration polarization capacitance and the discretization equation of the single battery equivalent model of each single battery.

4. The method for calculating model parameters of single cells according to claim 3, wherein the calculating the dynamic voltage of each single cell specifically comprises:

measuring the output voltage U of each single battery_L,i；

According to the formula U_d,i＝U_L,i-U_ocvCalculating the dynamic voltage U of each single battery_d,i(ii) a Wherein, U_ocvIs the open circuit voltage of the single battery; n, n is the number of single batteries in the battery module.

5. The method for calculating model parameters of single batteries according to claim 4, wherein the estimating the ohmic internal resistance of each single battery according to the average ohmic internal resistance and the dynamic voltage of the single battery specifically comprises:

according to the average ohmic internal resistance and the relational expression that the ratio of the ohmic internal resistance to the average ohmic internal resistance of the single batteries is equal to the ratio of the dynamic voltage to the average dynamic voltage of the single batteries, the ohmic internal resistance of each single battery is calculated, and the following conditions are met:

wherein R is_0,iIs the ohmic internal resistance, R, of the cell_0mTo average ohmic internal resistance, U_d,iIs the dynamic voltage of the cell, U_dmN, n is the number of single cells in the battery module.

6. The method for calculating model parameters of single cells according to claim 3, wherein the calculating of the electric polarization voltage and the concentration polarization voltage of each single cell specifically comprises:

according to the formulaCalculating the electric polarization voltage and the concentration polarization voltage of each single battery;

wherein, U_1,iIs the electric polarization voltage of the single battery; u shape_2,iIs the concentration polarization voltage of the single battery; u shape_d,iIs the dynamic voltage of the single battery; r_0,iThe ohmic internal resistance of the single battery is; i is_LIs the current of the battery module; r_1mTo average internal resistance of electric polarization, C_1mIs an average electric polarization capacitance; r_2mThe average concentration polarization internal resistance; c_2mIs an average concentration polarization capacitance; n, n is the number of single batteries in the battery module.

7. The method for calculating model parameters of single cells according to claim 6, wherein the calculating the internal polarization resistance and the electric polarization capacitance of each single cell according to the electric polarization voltage, the average internal polarization resistance, the average electric polarization capacitance and the discretization equation of the equivalent single cell model specifically comprises:

according to each of said cellsElectric polarization voltage U_1,iThe average internal polarization resistance R_1mThe average electric polarization capacitor C_1mAnd a simplified formula of discretization equation of the equivalent model of the single batteryCalculating the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery by the following calculation formula_1,iC_1,i：

According to the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery_1,iC_1,iAnd discretization equation of said cell equivalent modelCalculating the electric polarization internal resistance R of each single battery by the following calculation formula_1,i：

R_1,i＝R_1m×B₁

According to the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery_1,iC_1,iAnd the internal polarization resistance R of each single battery_1,iCalculating the electric polarization capacitance C of each single battery_1,i；

Wherein i is 1,2, n, n is the number of single batteries in the battery module; i is_LIs the current of the battery module; k is the current time; Δ t is the sampling period of the current and voltage, i.e., the time difference between time k and time (k-1).

8. The method for calculating model parameters of single cells according to claim 6, wherein the calculating the concentration polarization internal resistance and the concentration polarization capacitance of each single cell according to the concentration polarization voltage, the average concentration polarization internal resistance, the average concentration polarization capacitance and the discretization equation of the single cell equivalent model specifically comprises:

according to the concentration polarization voltage U of each single battery_2,iThe average concentration polarization internal resistance R_2mThe average concentration polarization capacitance C_2mAnd a simplified formula of discretization equation of the equivalent model of the single batteryCalculating the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery by the following calculation formula_2,iC_2,i：

According to the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery_2,iC_2,iAnd discretization equation of said cell equivalent modelCalculating the concentration polarization internal resistance R of each single battery by the following calculation formula_2,iSatisfies the following conditions:

R_2,i＝R_2m×B₂

according to the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery_2,iC_2,iAnd the concentration polarization internal resistance R of each single battery_2,iCalculating the concentration polarization capacitance C of each single battery_2,i；

Wherein i is 1,2, n, n is the number of single batteries in the battery module; i is_LIs the current of the battery module; k is the current time; Δ t is the sampling period of the current and voltage, i.e., the time difference between time k and time (k-1).

9. The method for calculating model parameters of a battery cell according to claim 1, wherein the calculating an average set of model parameters of the battery module according to an average equivalent model of the battery module specifically comprises:

constructing an average equivalent model of the battery module;

and calculating the average model parameter group of the battery module by adopting a recursive least square method according to the discretization equation of the average equivalent model of the battery module.

10. The method for calculating the model parameters of the single battery according to claim 1, wherein the average equivalent model of the battery module and the equivalent model of the single battery are both thevenin second-order equivalent circuit models.

11. The method of calculating model parameters of a battery cell according to claim 1, wherein after calculating the set of model parameters of each battery cell in the battery module according to the set of average model parameters and the discretization equation of the battery cell equivalent model, the method further comprises:

and monitoring the running state of the battery module according to the model parameter group of each single battery.

12. An apparatus for calculating model parameters of a battery cell, comprising:

the average model parameter group calculation module is used for calculating an average model parameter group of the battery module according to an average equivalent model of the battery module;

and the single battery model parameter group calculating module is used for calculating the model parameter group of each single battery in the battery module according to the average model parameter group and the discretization equation of the single battery equivalent model of the battery module.

13. A model parameter calculation apparatus for a battery cell, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, the processor implementing the model parameter calculation method for a battery cell according to any one of claims 1 to 11 when executing the computer program.

14. A computer-readable storage medium, comprising a stored computer program, wherein when the computer program runs, the computer-readable storage medium controls a device to execute the method for calculating model parameters of a battery cell according to any one of claims 1 to 11.

Technical Field

The invention relates to the technical field of batteries, in particular to a method, a device and a medium for calculating model parameters of a single battery.

Background

The lithium ion battery is gradually the most widely used type of power battery for electric vehicles due to its characteristics of high energy density, long cycle life, low self-discharge rate, etc. In order to meet the use requirements of long endurance and high power of the electric automobile, the vehicle-mounted lithium ion power battery module is generally formed by connecting a plurality of single batteries in series.

In the use of car, need monitor the running state of battery module. In the prior art, parameter information of a battery module is generally identified by establishing an average equivalent model of the battery module to monitor an operating state of the battery module.

However, in the process of implementing the invention, the inventor finds that the prior art has at least the following problems: due to the difference between the manufacturing and using processes, the problem of inconsistent performance of a large number of single batteries in the battery module is inevitable. However, the influence of inconsistent performance of the single batteries on the dynamic characteristics and performance of the whole battery module is large, and if only parameter information of the average equivalent model of the battery module is estimated, the running state of each single battery cannot be known, so that the running state of the whole battery module cannot be accurately reflected, and a reliable basis cannot be provided for scenes such as fault diagnosis of an automobile.

Disclosure of Invention

The embodiment of the invention aims to provide a method, a device and a medium for calculating model parameters of single batteries, which can accurately calculate the model parameters of each single battery in a battery module and effectively improve the efficiency of calculating the model parameters of the single batteries.

In order to achieve the above object, an embodiment of the present invention provides a method for calculating model parameters of a single battery, including:

calculating an average model parameter group of the battery module according to an average equivalent model of the battery module;

and calculating the model parameter group of each single battery in the battery module according to the average model parameter group and the discretization equation of the equivalent model of the single battery of the battery module.

As an improvement of the above scheme, the average model parameter group includes an average ohmic internal resistance, an average electric polarization capacitance, an average concentration polarization internal resistance, and an average concentration polarization capacitance; the model parameter set comprises ohmic internal resistance, electric polarization capacitance, concentration polarization internal resistance and concentration polarization capacitance of each single battery;

as an improvement of the above scheme, the calculating a model parameter set of each cell according to the average model parameter set and the discretization equation of the cell equivalent model specifically includes:

calculating the dynamic voltage of each single battery;

estimating the ohmic internal resistance of each single battery according to the average ohmic internal resistance and the dynamic voltage of the single battery;

calculating the electric polarization voltage and the concentration polarization voltage of each single battery;

calculating the electric polarization internal resistance and the electric polarization capacitance of each single battery according to the electric polarization voltage, the average electric polarization internal resistance, the average electric polarization capacitance and the discretization equation of the single battery equivalent model of each single battery;

and calculating the concentration polarization internal resistance and the concentration polarization capacitance of each single battery according to the concentration polarization voltage, the average concentration polarization internal resistance, the average concentration polarization capacitance and the discretization equation of the single battery equivalent model of each single battery.

As an improvement of the above scheme, the calculating the dynamic voltage of each of the single batteries specifically includes:

measuring the output voltage U of each single battery_L,i；

According to the formula U_d,i＝U_L,i-U_ocvCalculating the dynamic voltage U of each single battery_d,i(ii) a Wherein, U_ocvIs the open circuit voltage of the single battery; n, n is the number of single batteries in the battery module.

As an improvement of the above scheme, the estimating the ohmic internal resistance of each single battery according to the average ohmic internal resistance and the dynamic voltage of the single battery specifically includes:

according to the average ohmic internal resistance and the relational expression that the ratio of the ohmic internal resistance to the average ohmic internal resistance of the single batteries is equal to the ratio of the dynamic voltage to the average dynamic voltage of the single batteries, the ohmic internal resistance of each single battery is calculated, and the following conditions are met:

wherein R is_0,iIs the ohmic internal resistance, R, of the cell_0mTo average ohmic internal resistance, U_d,iIs the dynamic voltage of the cell, U_dmN, n is the number of single cells in the battery module.

As an improvement of the above scheme, the calculating the electric polarization voltage and the concentration polarization voltage of each unit cell specifically includes:

according to the formulaCalculating the electric polarization voltage and the concentration polarization voltage of each single battery;

wherein, U_1,iIs the electric polarization voltage of the single battery; u shape_2,iIs the concentration polarization voltage of the single battery; u shape_d,iIs the dynamic voltage of the single battery; r_0,iThe ohmic internal resistance of the single battery is; i is_LIs the current of the battery module; r_1mTo average internal resistance of electric polarization, C_1mIs an average electric polarization capacitance; r_2mThe average concentration polarization internal resistance; c_2mIs an average concentration polarization capacitance; n, n is the number of single batteries in the battery module.

As an improvement of the above solution, the calculating the electric polarization internal resistance and the electric polarization capacitance of each unit cell according to the electric polarization voltage, the average electric polarization internal resistance, the average electric polarization capacitance, and the discretization equation of the unit cell equivalent model specifically includes:

according to the electric polarization voltage U of each single battery_1,iThe averaging electrodeChange internal resistance R_1mThe average electric polarization capacitor C_1mAnd a simplified formula of discretization equation of the equivalent model of the single batteryCalculating the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery by the following calculation formula_1,iC_1,i：

According to the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery_1,iC_1,iAnd discretization equation of said cell equivalent modelCalculating the electric polarization internal resistance R of each single battery by the following calculation formula_1,i：

R_1,i＝R_1m×B₁

According to the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery_1,iC_1,iAnd the internal polarization resistance R of each single battery_1,iCalculating the electric polarization capacitance C of each single battery_1,i；

Wherein i is 1,2, n, n is the number of single batteries in the battery module; i is_LIs the current of the battery module; k is the current time; Δ t is the sampling period of the current and voltage, i.e., the time difference between time k and time (k-1).

As an improvement of the above scheme, the calculating a concentration polarization internal resistance and a concentration polarization capacitance of each of the single cells according to the concentration polarization voltage, the average concentration polarization internal resistance, the average concentration polarization capacitance, and a discretization equation of the single cell equivalent model specifically includes:

according to the concentration polarization voltage U of each single battery_2,iThe average concentration polarization internal resistance R_2mThe average concentration polarization capacitance C_2mAnd a simplified formula of discretization equation of the equivalent model of the single batteryCalculating the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery by the following calculation formula_2,iC_2,i：

According to the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery_2,iC_2,iAnd discretization equation of said cell equivalent modelCalculating the concentration polarization internal resistance R of each single battery by the following calculation formula_2,iSatisfies the following conditions:

R_2,i＝R_2m×B₂

according to the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery_2,iC_2,iAnd the concentration polarization internal resistance R of each single battery_2,iCalculating the concentration polarization capacitance C of each single battery_2,i；

Wherein i is 1,2, n, n is the number of single batteries in the battery module; i is_LIs the current of the battery module; k is the current time; Δ t is the sampling period of the current and voltage, i.e., the time difference between time k and time (k-1).

As an improvement of the above scheme, the calculating an average model parameter set of the battery module according to the average equivalent model of the battery module specifically includes:

constructing an average equivalent model of the battery module;

and calculating the average model parameter group of the battery module by adopting a recursive least square method according to the discretization equation of the average equivalent model of the battery module.

As an improvement of the scheme, the average equivalent model of the battery module and the equivalent model of the single battery are both Thevenin second-order equivalent circuit models.

As an improvement of the above solution, after the calculating the model parameter set of each battery cell in the battery module according to the discretization equation of the average model parameter set and the equivalent model of the battery cell, the method further includes:

and monitoring the running state of the battery module according to the model parameter group of each single battery.

The embodiment of the present invention further provides a device for calculating model parameters of a single battery, including:

the average model parameter group calculation module is used for calculating an average model parameter group of the battery module according to an average equivalent model of the battery module;

and the single battery model parameter group calculating module is used for calculating the model parameter group of each single battery in the battery module according to the average model parameter group and the discretization equation of the single battery equivalent model of the battery module.

The embodiment of the present invention further provides a device for calculating model parameters of a single battery, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, the method for calculating model parameters of a single battery as described in any one of the above is implemented.

The embodiment of the present invention further provides a computer-readable storage medium, where the computer-readable storage medium includes a stored computer program, and when the computer program runs, the apparatus where the computer-readable storage medium is located is controlled to execute the method for calculating model parameters of a single battery according to any one of the above items.

Compared with the prior art, the method, the device and the medium for calculating the model parameters of the single battery disclosed by the invention are used for calculating the average model parameter group of the battery module according to the average equivalent model of the battery module, wherein the average model parameter group comprises average ohmic internal resistance, average electric polarization capacitance, average concentration polarization internal resistance and average concentration polarization capacitance; and calculating a model parameter set of each single battery in the battery module according to the average model parameter set and a discretization equation of the single battery equivalent model by constructing a single battery equivalent model of the battery module, wherein the model parameter set comprises ohmic internal resistance, electric polarization capacitance, concentration polarization internal resistance and concentration polarization capacitance of each single battery. Compared with a method for separately identifying parameters and monitoring states of each single battery model, the method for calculating the model parameters of the single battery provided by the embodiment of the invention can greatly reduce the calculation amount of a battery management system and reduce the operation load of a processor on the basis of accurately calculating the module parameter group of each single battery model. In addition, the model parameters of the single batteries obtained through calculation in the embodiment of the invention can be used for evaluating the running states of the single batteries, and in the process of monitoring the running states of the battery module, the inconsistency of the parameters of each single battery in the battery module is considered, so that the running states of the whole battery module can be reflected more accurately, and a more reliable data basis is provided for fault diagnosis and a cell balancing algorithm of a battery management system.

Drawings

Fig. 1 is a schematic flow chart illustrating steps of a method for calculating model parameters of a single battery according to an embodiment of the present invention;

fig. 2 is a schematic circuit diagram of an average equivalent model of a battery module according to an embodiment of the invention;

fig. 3 is a schematic circuit diagram of an equivalent model of a single battery of the battery module according to the embodiment of the invention;

FIG. 4 is a flowchart illustrating steps of calculating a set of model parameters of a single battery according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a device for calculating model parameters of a single battery according to a second embodiment of the present invention;

fig. 6 is a schematic structural diagram of a device for calculating model parameters of a single battery according to a third embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 is a schematic flow chart illustrating steps of a method for calculating model parameters of a single battery according to an embodiment of the present invention. The method for calculating the model parameters of the single battery provided by the embodiment of the invention is implemented through steps S1 to S2:

s1, calculating an average model parameter group of the battery module according to the average equivalent model of the battery module;

in an embodiment of the present invention, the average model parameter set includes an average ohmic internal resistance, an average electric polarization capacitance, an average concentration polarization internal resistance, and an average concentration polarization capacitance. Taking the battery module consisting of a plurality of single batteries as a whole to construct an average equivalent model of the battery module, and calculating the average ohmic internal resistance R of the battery module according to the average equivalent model_0mAverage internal resistance to electric polarization R_1mAverage electric polarization capacitance C_1mAverage concentration polarization internal resistance R_2mSum average concentration polarization capacitance C_2mAnd the average model parameter group is used for monitoring the running state of the battery module.

As a preferred embodiment, step S1 is performed through steps S11 to S12:

and S11, constructing an average equivalent model of the battery module.

And S12, calculating the average model parameter group of the battery module by adopting a recursive least square method according to the discretization equation of the average equivalent model of the battery module.

Fig. 2 is a schematic circuit structure diagram of an average equivalent model of the battery module according to the embodiment of the present invention. In the embodiment of the invention, the average equivalent model of the battery module is a Thevenin second-order equivalent circuit model. The relevant parameters of the average equivalent model of the battery module comprise: average ohmic internal resistance R_0mAverage internal resistance to electric polarization R_1mAverage electric polarization capacitance C_1mAverage concentration polarization internal resistance R_2mAverage concentration polarization capacitance C_2mAverage electric polarization voltage U_1mAverage concentration polarization voltage U_2mOpen circuit voltage U of single battery_ocvAverage output voltage U of battery module_LmAnd current I of the battery module_L。

Wherein, the open circuit voltage U of the single battery_ocvThe nominal value of the single battery in the battery module can be obtained by looking up a table. Average output voltage U of battery module_LmTotal output voltage U through battery module_L,moduleAnd the number n of the single batteries in the battery module passes through a formulaCalculated to obtain the total output voltage U_L,moduleAnd current I of the battery module_LCan be obtained by measurement.

The discrete equation of the average equivalent model of the battery module includes:

wherein k is the current moment; Δ t is the sampling period of the current and voltage, i.e., the time difference between time k and time (k-1).

It is understood that the discretization equation can represent the relationship between the data of the previous moment and the data of the next moment. When enough current and voltage acquisition points exist, the average model parameter set [ R ] of the battery module can be obtained by calculation according to the discrete equation of the average equivalent model of the battery module and by adopting a conventional identification method to recur a least square method_0m,R_1m,C_1m,R_2m,C_2m]。

S2, calculating a model parameter group of each single battery in the battery module according to the average model parameter group and a discretization equation of a single battery equivalent model of the battery module;

in an embodiment of the present invention, the set of model parameters includes ohmic internal resistance, electric polarization capacitance, concentration polarization internal resistance, and concentration polarization capacitance of each single battery.

Specifically, referring to fig. 3, a schematic circuit structure diagram of a single battery equivalent model of the battery module in the embodiment of the present invention is shown. In the embodiment of the invention, the single battery equivalent model of the battery module is a Thevenin second-order equivalent circuit model. The relevant parameters of each single battery in the equivalent model of the single battery of the battery module comprise: ohmic internal resistance R_0,iInternal resistance of electric polarization R_1,iAn electric polarization capacitor C_1,iInternal resistance R of concentration polarization_2,iConcentration polarization capacitor C_2,iElectric polarization voltage U_1,iConcentration polarization voltage U_2,iOpen circuit voltage U of single battery_ocvOutput voltage U of single battery_L,iAnd current I_L. Wherein, i is 1,2, n, n is the number of single batteries in the battery module.

In the embodiment of the invention, the average model parameter set [ R ] is obtained by calculating according to the average equivalent model of the battery module_0m,R_1m,C_1m,R_2m,C_2m]And then, further constructing a single battery equivalent model of the battery module, and calculating to obtain each single battery according to the average model parameter group and the single battery equivalent model of the battery modulePool model parameter set [ R ]_0,i,R_1,i,C_1,i,R_2,i,C_2,i]。

As a preferred implementation manner, refer to fig. 4, which is a schematic flow chart illustrating a step of calculating a set of model parameters of a single battery in an embodiment of the present invention. Step S2 is specifically executed by steps S21 to S25:

and S21, calculating the dynamic voltage of each single battery.

And S22, estimating the ohm internal resistance of each single battery according to the average ohm internal resistance and the dynamic voltage of the single battery.

Specifically, the method for calculating the dynamic voltage of each of the single batteries specifically includes:

s211, measuring the output voltage U of each single battery_L,i；

S212, according to the formula U_d,i＝U_L,i-U_ocvCalculating the dynamic voltage U of each single battery_d,i(ii) a Wherein, U_ocvIs the open circuit voltage of the single battery; n, n is the number of single batteries in the battery module.

Further, according to the working principle of the battery module, the ohmic internal resistance R of each single battery_0,iRatio of the ratio to the dynamic U of each cell_d,iThe ratio of the two is relatively close, so that:

R_0,1:R_0,2:...:R_0,n:R_0m≈U_d,1:U_d,2:...:U_d,n:U_dm；

according to the average ohmic internal resistance R_0mAnd the ratio of the ohmic internal resistance of the single batteries to the average ohmic internal resistance is equal to the relation of the dynamic voltage of the single batteries to the average dynamic voltage, and the ohmic internal resistance R of each single battery is calculated_0,iAnd satisfies the following conditions:

wherein, U_dmN, n is the number of single cells in the battery module.

And S23, calculating the electric polarization voltage and the concentration polarization voltage of each single battery.

S24, calculating the electric polarization internal resistance and electric polarization capacitance of each single battery according to the electric polarization voltage, the average electric polarization internal resistance, the average electric polarization capacitance and the discretization equation of the single battery equivalent model;

and S25, calculating the concentration polarization internal resistance and the concentration polarization capacitance of each single battery according to the concentration polarization voltage, the average concentration polarization internal resistance, the average concentration polarization capacitance and the discretization equation of the single battery equivalent model.

In the embodiment of the invention, the formula is usedAnd the average model parameter group is used for calculating the electric polarization voltage U of each single battery_1,iSum concentration polarization voltage U_2,i。

Further, the discretization equation of the equivalent model of the single battery is as follows:

aiming at the first RC parallel link of each single battery in the battery module, the sampling period is generally far less than the time constant R_1,iC_1,iThus:obtaining a simplified formula of the discretization equation of the equivalent model of the single battery

Thus, there are:

finishing to obtain:

order:and construct a normalized weight vector

It is possible to obtain,then the process of the first step is carried out,

therefore, in the embodiment of the present invention, the electric polarization voltage U of each of the unit cells is determined according to_1,iThe average internal polarization resistance R_1mThe average electric polarization capacitor C_1mAnd a simplified formula of discretization equation of the equivalent model of the single batteryCalculating the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery by the following calculation formula_1,iC_1,i：

Further, according to the discretization equation of the equivalent model of the single batteryIt is possible to obtain,

therefore, there are:

order:and construct a normalized weight vectorCan be obtained of_1,1:R_1,2:...:R_1,n＝R_1m·B₁。

Therefore, in the embodiment of the invention, the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery is determined according to the electric polarization internal resistance_1,iC_1,iCalculating the electric polarization internal resistance R of each single battery by the following calculation formula_1,i：

R_1,i＝R_1m×B₁

Finally, according to the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery_1,iC_1,iAnd the internal polarization resistance R of each single battery_1,iCalculating the electric polarization capacitance C of each single battery_1,i。

Similarly, for the first RC parallel link of each single battery in the battery module, the same method can be used to calculate the concentration polarization internal resistance R of each single battery_2,iSum concentration polarization capacitance C_2,i。

According to the concentration polarization voltage U of each single battery_2,iThe average concentration polarization internal resistance R_2mThe average concentration polarization capacitance C_2mAnd a simplified formula of discretization equation of the equivalent model of the single batteryCalculating the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery by the following calculation formula_2,iC_2,i：

According to the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery_2,iC_2,iAnd discretization equation of said cell equivalent modelCalculating the concentration polarization internal resistance R of each single battery by the following calculation formula_2,iSatisfies the following conditions:

R_2,i＝R_2m×B₂

according to the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery_2,iC_2,iAnd the concentration polarization internal resistance R of each single battery_2,iCalculating the concentration polarization capacitance C of each single battery_2,i。

Wherein i is 1,2, n, n is the number of single batteries in the battery module; i is_LIs the current of the battery module; k is the current time; Δ t is the sampling period of the current and voltage, i.e., the time difference between time k and time (k-1).

Therefore, through the above procedure of calculating the model parameter set of the single battery, the model parameter set [ R ] corresponding to each single battery in the battery module can be calculated_0,i,R_1,i,C_1,i,R_2,i,C_2,i]。

As a preferred embodiment, after the step S2, the method for calculating model parameters of a unit battery further includes the step S3:

and S3, monitoring the running state of the battery module according to the model parameter group of each single battery.

According to the model parameter group [ R ] corresponding to each single battery_0,i,R_1,i,C_1,i,R_2,i,C_2,i]The running state of each single battery can be evaluated, and then the running state of the whole battery module can be accurately monitored according to the running state of each single battery.

The embodiment of the invention provides a method for calculating model parameters of a single battery, which comprises the steps of calculating an average model parameter group of a battery module according to an average equivalent model of the battery module, wherein the average model parameter group comprises average ohmic internal resistance, average electric polarization capacitance, average concentration polarization internal resistance and average concentration polarization capacitance; and calculating a model parameter set of each single battery in the battery module according to the average model parameter set and a discretization equation of the single battery equivalent model by constructing a single battery equivalent model of the battery module, wherein the model parameter set comprises ohmic internal resistance, electric polarization capacitance, concentration polarization internal resistance and concentration polarization capacitance of each single battery. Compared with a method for separately identifying parameters and monitoring states of each single battery model, the method for calculating the model parameters of the single battery provided by the embodiment of the invention can greatly reduce the calculation amount of a battery management system and reduce the operation load of a processor on the basis of accurately calculating the module parameter group of each single battery model. In addition, the model parameters of the single batteries obtained through calculation in the embodiment of the invention can be used for evaluating the running states of the single batteries, and in the process of monitoring the running states of the battery module, the inconsistency of the parameters of each single battery in the battery module is considered, so that the running states of the whole battery module can be reflected more accurately, and a more reliable data basis is provided for fault diagnosis and a cell balancing algorithm of a battery management system.

Fig. 5 is a schematic structural diagram of a device for calculating model parameters of a single battery according to a second embodiment of the present invention. The embodiment of the present invention provides a single battery model parameter calculation apparatus 20, which includes an average model parameter set calculation module 21 and a single battery model parameter set calculation module 22, wherein,

the average model parameter group calculating module 21 is configured to calculate an average model parameter group of the battery module according to an average equivalent model of the battery module;

the battery cell model parameter group calculation module 22 is configured to calculate a model parameter group of each battery cell in the battery module according to the average model parameter group and a discretization equation of a battery cell equivalent model of the battery module;

in a preferred embodiment, the average model parameter set includes an average ohmic internal resistance, an average electric polarization capacitance, an average concentration polarization internal resistance, and an average concentration polarization capacitance; the model parameter set comprises ohmic internal resistance, electric polarization capacitance, concentration polarization internal resistance and concentration polarization capacitance of each single battery;

the average model parameter set calculating module 21 is specifically configured to:

constructing an average equivalent model of the battery module;

and calculating the average model parameter group of the battery module by adopting a recursive least square method according to the discretization equation of the average equivalent model of the battery module.

As a preferred embodiment, the battery cell model parameter set calculating module 22 specifically includes:

a dynamic voltage calculating unit 221 for calculating a dynamic voltage of each of the unit cells;

an ohmic resistance estimation unit 222, configured to estimate an ohmic internal resistance of each single battery according to the average ohmic internal resistance and the dynamic voltage of the single battery;

a polarization voltage calculation unit 223 for calculating an electric polarization voltage and a concentration polarization voltage of each of the unit cells;

an electric polarization internal resistance and capacitance calculating unit 224, configured to calculate an electric polarization internal resistance and an electric polarization capacitance of each single battery according to the electric polarization voltage of each single battery, the average electric polarization internal resistance, the average electric polarization capacitance, and a discretization equation of the single battery equivalent model;

and a concentration polarization internal resistance and capacitance calculating unit 225, configured to calculate the concentration polarization internal resistance and the concentration polarization capacitance of each single cell according to the concentration polarization voltage of each single cell, the average concentration polarization internal resistance, the average concentration polarization capacitance, and a discretization equation of the single cell equivalent model.

Specifically, the dynamic voltage calculating unit 221 is specifically configured to:

measuring the output voltage U of each single battery_L,i(ii) a According to the formula U_d,i＝U_L,i-U_ocvCalculating the dynamic voltage U of each single battery_d,i(ii) a Wherein, U_ocvIs the open circuit voltage of the single battery; n, n is the number of single batteries in the battery module.

The ohmic resistance estimation unit 222 is specifically configured to:

according to the average ohmic internal resistance and the relational expression that the ratio of the ohmic internal resistance to the average ohmic internal resistance of the single batteries is equal to the ratio of the dynamic voltage to the average dynamic voltage of the single batteries, the ohmic internal resistance of each single battery is calculated, and the following conditions are met:

wherein R is_0,iIs the ohmic internal resistance, R, of the cell_0mTo average ohmic internal resistance, U_d,iIs the dynamic voltage of the cell, U_dmN, n is the number of single cells in the battery module.

The polarization voltage calculation unit 223 is specifically configured to:

according to the formulaCalculating the electric polarization voltage and the concentration polarization voltage of each single battery;

wherein, U_1,iIs the electric polarization voltage of the single battery; u shape_2,iIs the concentration polarization voltage of the single battery; u shape_d,iIs the dynamic voltage of the single battery; r_0,iThe ohmic internal resistance of the single battery is; i is_LIs the current of the battery module; r_1mTo average internal resistance of electric polarization, C_1mIs an average electric polarization capacitance; r_2mThe average concentration polarization internal resistance; c_2mIs an average concentration polarization capacitance; n, n is the number of single batteries in the battery module.

The electric polarization internal resistance and capacitance calculating unit 224 is specifically configured to:

according to the electric polarization voltage U of each single battery_1,iThe average internal polarization resistance R_1mThe average electric polarization capacitor C_1mAnd a simplified formula of discretization equation of the equivalent model of the single batteryCalculating the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery by the following calculation formula_1,iC_1,i：

According to the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery_1,iC_1,iAnd discretization equation of said cell equivalent modelCalculating the electric polarization internal resistance R of each single battery by the following calculation formula_1,i：

R_1,i＝R_1m×B₁

According to the product R of the electric polarization internal resistance and the electric polarization capacitance of each single battery_1,iC_1,iAnd the internal polarization resistance R of each single battery_1,iCalculating the electric polarization capacitance C of each single battery_1,i；

Wherein i is 1,2, n, n is the number of single batteries in the battery module; i is_LIs the current of the battery module; k is the current time; Δ t being current and voltageThe sampling period, i.e., the time difference between time k and time (k-1).

The concentration polarization internal resistance and capacitance calculating unit 225 is specifically configured to:

according to the concentration polarization voltage U of each single battery_2,iThe average concentration polarization internal resistance R_2mThe average concentration polarization capacitance C_2mAnd a simplified formula of discretization equation of the equivalent model of the single batteryCalculating the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery by the following calculation formula_2,iC_2,i：

According to the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery_2,iC_2,iAnd discretization equation of said cell equivalent modelCalculating the concentration polarization internal resistance R of each single battery by the following calculation formula_2,iSatisfies the following conditions:

R_2,i＝R_2m×B₂

according to the product R of the concentration polarization internal resistance and the concentration polarization capacitance of each single battery_2,iC_2,iAnd the concentration polarization internal resistance R of each single battery_2,iCalculating the concentration polarization capacitance C of each single battery_2,i；

Wherein i is 1,2, n, n is the number of single batteries in the battery module; i is_LIs the current of the battery module; k is the current time; Δ t is the sampling period of the current and voltage, i.e., the time difference between time k and time (k-1).

In a preferred embodiment, the model parameter calculation device 20 of the single battery further includes an operation state monitoring module 23;

the operation state monitoring module 23 is configured to monitor an operation state of the battery module according to the model parameter set of each single battery.

It should be noted that, the device for calculating model parameters of a single battery according to the embodiment of the present invention is used to execute all the process steps of the method for calculating model parameters of a single battery according to the above embodiment, and the working principles and beneficial effects of the two are in one-to-one correspondence, so that details are not repeated.

The embodiment two of the invention provides a device for calculating model parameters of a single battery, wherein an average model parameter group calculating module calculates an average model parameter group of a battery module according to an average equivalent model of the battery module, wherein the average model parameter group comprises average ohmic internal resistance, average electric polarization capacitance, average concentration polarization internal resistance and average concentration polarization capacitance; and calculating the model parameter set of each single battery in the battery module by a single battery model parameter set calculation module according to the average model parameter set and the discretization equation of the single battery equivalent model, wherein the model parameter set comprises the ohmic internal resistance, the electric polarization capacitance, the concentration polarization internal resistance and the concentration polarization capacitance of each single battery. Compared with a method for separately identifying parameters and monitoring states of each single battery model, the method for calculating the model parameters of the single battery provided by the embodiment of the invention can greatly reduce the calculation amount of a battery management system and reduce the operation load of a processor on the basis of accurately calculating the module parameter group of each single battery model. In addition, the model parameters of the single batteries obtained through calculation in the embodiment of the invention can be used for evaluating the running states of the single batteries, and in the process of monitoring the running states of the battery module, the inconsistency of the parameters of each single battery in the battery module is considered, so that the running states of the whole battery module can be reflected more accurately, and a more reliable data basis is provided for fault diagnosis and a cell balancing algorithm of a battery management system. .

Fig. 6 is a schematic structural diagram of a device for calculating model parameters of a single battery according to a third embodiment of the present invention. The device 30 for calculating model parameters of a single battery according to an embodiment of the present invention includes a processor 31, a memory 32, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, the method for calculating model parameters of a single battery according to an embodiment of the present invention is implemented.

The embodiment of the present invention further provides a computer-readable storage medium, where the computer-readable storage medium includes a stored computer program, and when the computer program runs, the apparatus where the computer-readable storage medium is located is controlled to execute the method for calculating model parameters of a single battery according to the first embodiment.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-only memory (ROM), a Random Access Memory (RAM), or the like.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.