CN-122021242-A - Sodium ion battery SOC accurate estimation method and battery management system based on improved aerodynamic model

CN122021242ACN 122021242 ACN122021242 ACN 122021242ACN-122021242-A

Abstract

The invention provides a sodium ion battery SOC accurate estimation method and a battery management system based on an improved aerodynamic model, comprising the following steps of establishing an aerodynamic model for describing charge-discharge and polarization processes of a battery, wherein the aerodynamic model constructs a gas total solubility equation in a process of dissolving gas in liquid by simultaneously considering gas gap filling solubility and gas hydration solubility; and estimating the state of charge (SOC) of the battery based on the aerodynamic model and the input and output data of the battery. The traditional aerodynamic model simulates the battery polarization effect only through the gas gap filling solubility, and is difficult to completely describe the voltage rebound characteristic related to the strong polarization reaction, so that a large error exists in the model. Therefore, the invention introduces the gas hydration solubility in the modeling and improves the aerohydrodynamic model, thereby more accurately representing the polarization dynamic behavior of the sodium ion battery and improving the SOC estimation precision.

Inventors

WANG YAPING
LIU DUANYOU
LI HUANHUAN
WANG KUI
Wu Dianfan
WANG NAN
JIANG HAOBIN

Assignees

江苏大学

Dates

Publication Date: 20260512
Application Date: 20251219

Claims (10)

1. The sodium ion battery SOC accurate estimation method based on the improved aerodynamic model is characterized by comprising the following steps of: Establishing a aerodynamic model for describing the charge-discharge and polarization processes of the battery, wherein the aerodynamic model constructs a gas total solubility equation in which gas is dissolved in liquid by simultaneously considering gas gap filling solubility and gas hydration solubility; And estimating the state of charge (SOC) of the battery based on the aerodynamic model and the input and output data of the battery.
2. The method for accurate estimation of SOC of a sodium ion battery based on an improved aerodynamic model of claim 1, wherein the aerodynamic model describes the charge-discharge and polarization process of the battery by simulating a closed system containing high pressure gas and liquid, wherein the gas total solubility equation describing the gas-to-liquid process contains both gas gap-filling solubility terms and gas hydration solubility terms; deducing a charge and discharge state estimation model of the battery based on the aerodynamic model; acquiring dynamic test experimental data of the sodium ion battery, and identifying model parameters of the charge and discharge state estimation model; Based on the identified model parameters and the battery current and voltage data acquired in real time, estimating the state of charge (SOC) of the battery.
3. The method for accurately estimating the SOC of the sodium ion battery based on the improved aerodynamic model of claim 2, wherein the gas total solubility equation is: Where n c1 represents the amount of the substance dissolved in the liquid by the gas at time T 1 , n j1 represents the amount of the substance dissolved in the liquid by the gas gap filling at time T 1 , ɸ m represents the effective gap constant of the gas molecules, V w represents the volume of the liquid, b m is the van der waals volume of the gas molecules, n h1 represents the amount of the substance dissolved in the liquid by the gas hydration at time T 1 , K p represents the gas hydration equilibrium constant, P 1 represents the gas pressure in the container at this time, R is the thermodynamic constant, and T represents the thermodynamic temperature of the gas.
4. The method for accurately estimating the SOC of a sodium ion battery based on an improved aerodynamic model according to claim 3, wherein the battery charge-discharge state estimation model derived based on the gas total solubility equation has a relationship between a terminal voltage U L and a current I expressed as: Wherein, U 1 represents the open circuit voltage OCV of the battery at time t 1 , U 2 represents the intermediate transient voltage of the battery at time t 2 , U 3 represents the open circuit voltage of the battery at time t 3 , U L represents the terminal voltage of the battery at time t 3 , and k 1 、k 2 、k 3 、k 4 、k 5 is a model parameter.
5. The method for accurately estimating the SOC of the sodium ion battery based on the improved aerodynamic model of claim 4, wherein the establishing the aerodynamic model for describing the charge-discharge and polarization processes of the battery specifically comprises the following steps: Assuming that in a certain closed container, high-pressure gas with a volume V and liquid with a volume V L exist, the pressure, the quantity and the temperature of substances of the high-pressure gas are respectively P, n and T, meanwhile, the quantity of substances of the gas dissolved in the liquid is n c , a switching valve is arranged on a pipeline above the closed container, the cross section area and the resistance coefficient of the valve are respectively S and mu, the gas pressure of an external pipe orifice of the valve switch is P L , the gas flow rate and the density in the pipeline are respectively V and ρ, and taking microscopic mass characteristics into consideration, the assumption is made that (1) the gas is regarded as a uniform medium, the temperature and the pressure in the gas area are equal everywhere, (2) the gas mass is ignored, and (3) the gas is not compressed; Assuming that the gas-liquid system is in an equilibrium state at time T 1 , the gas temperature is T 1 , the pressure of the gas is P 1 , the amount of gas substances is n 1 , the amount of substances of the gas dissolved in the liquid is n c1 , a valve switch at the top of the gas-liquid system is opened, the gas in the gas-liquid system is discharged outwards after a short period of time deltat, the flow rate is v, the comprehensive resistance coefficient of a pipeline in the gas discharging process is mu, the external pressure of a pipe orifice is P L , and the gas-liquid system is characterized in that The valve switch is turned off at the moment when the valve is turned off, the temperature of the gas in the system is T 2 , the pressure is P 2 , the amount of the gas substance is n 2 , the amount of the gas substance dissolved in the liquid is n c2 , the gas in the system is not balanced, the time when the gas reaches T 3 for a long time, the gas-liquid system reaches the balanced state again, the temperature of the gas in the system is T 3 , the pressure of the gas is P 3 , the amount of the gas substance is n 3 , and the amount of the gas substance dissolved in the liquid is n c3 .
6. The method for accurately estimating the SOC of the sodium ion battery based on the improved aerodynamic model of claim 5, wherein the model parameters k 1 、k 2 、k 3 、k 4 、k 5 are obtained by performing parameter identification by using a genetic algorithm and using voltage errors as optimization targets.
7. The method for accurately estimating SOC of sodium ion battery based on improved aerodynamic model of claim 6, wherein the population scale of the genetic algorithm is 100, the maximum iteration number is 200, the crossover probability is 0.8, the variation probability is 0.01, and the value of model parameter k 1 、k 2 、k 3 、k 4 、k 5 obtained by the identification of the genetic algorithm is the optimal parameter combination for minimizing voltage error, which is output: k 1 =9.590×10 -4 ,k 2 =0.41142,k 3 =1×10 -7 ,k 4 =8.90095×10 -5 ,k 5 =7.332×10 -4 .
8. The method for accurately estimating the SOC of the sodium ion battery based on the improved aerodynamic model according to claim 1, wherein the dynamic test experiment is a mixed pulse power characteristic HPPC experiment; The method validates under a variety of standard dynamic conditions including DST, FUDS, UDDS and CLTC.
9. The method for accurately estimating the SOC of the sodium ion battery based on the improved aerodynamic model of claim 1, wherein the maximum absolute error of the SOC estimation result obtained by the method is not more than 2.5%, and the average absolute error is not more than 1%.
10. A battery management system comprising a memory and a processor, the memory storing a computer program, the processor implementing the improved aerodynamic model-based accurate estimation method of sodium ion battery SOC of any of claims 1-9 when executing the computer program.

Description

Sodium ion battery SOC accurate estimation method and battery management system based on improved aerodynamic model Technical Field The invention belongs to the field of battery management systems, and particularly relates to a sodium ion battery SOC accurate estimation method based on an improved aerodynamic model and a battery management system. Background Along with continuous expansion of renewable energy grid-connected scale and rapid development of electric automobile industry, importance of large-scale energy storage technology is increasingly highlighted, although the lithium ion battery has advantages of high energy density, long cycle life and the like and takes precedence in related fields, further large-scale development of the lithium ion battery faces serious challenges of uneven lithium resource distribution, fluctuation of raw material price and shortage of key metal supply, under the background, the sodium ion battery becomes a novel energy storage system with great development potential by virtue of advantages of abundant sodium resource reserves, outstanding cost benefit, environmental friendliness and the like, and a Battery Management System (BMS) plays a vital role in ensuring safe and efficient operation of the sodium ion battery system, and utilizes a high-precision algorithm to dynamically estimate the state of charge (SOC) by monitoring parameters such as voltage, current and temperature of the battery in real time, so that the residual electric quantity of the battery is accurately mastered, and key data support is provided for balanced management, health state estimation and fault diagnosis of the system, and particularly in the sodium ion battery, a relatively linear open-circuit voltage curve has higher requirements on SOC estimation. At present, an SOC estimation method based on a model is mainly divided into two major types, namely an electrochemical model and an equivalent circuit model, wherein the electrochemical model is based on an electrochemical mechanism in a battery, and based on the coupling action of a state equation, a differential equation, a partial differential equation and the like, a system description is related to design parameters, such as terminal voltage, charge-discharge current and microscopic ion behaviors (such as lithium ion concentration distribution and interface charge transmission processes), the model has the accuracy of mechanism description, but is limited by a complex model structure and high calculation cost, the real-time operation requirement of a vehicle-mounted Micro Control Unit (MCU) is difficult to meet, the equivalent circuit model is used for simulating a charge-discharge dynamic process from the equivalent angle of the external characteristics of the battery, and an intuitive equivalent topological structure is constructed through circuit elements such as a capacitor, a resistor, an ideal voltage source and the like, the state equation form is relatively simple, a typical model comprises Rint, thevenin, PNGV, a multi-order RC model and the like, wherein the accuracy of SOC estimation is insufficient due to the structural simplification, the high-order RC model is used for introducing excessive parameters to be identified for high accuracy, and the uncertainty and complexity of parameter identification are aggravated, in addition, the stability of the full-SOC interval is ensured, the stability is equivalent, the effect is realized, the equivalent control circuit, the algorithm is normally has the same as the real-time algorithm, the fuzzy algorithm is applied to the vehicle-mounted algorithm, and the fuzzy algorithm is well-time-constrained, and the fuzzy algorithm is calculated, and has the real-time algorithm is applied to the real-time calculation algorithm. In summary, the two existing analytical models have limitations, and are difficult to meet the requirement of fast and high-precision estimation of the battery state, so that an analytical model and an SOC estimation method which can reflect the relationship between the temperature and the battery performance more accurately and describe the nonlinear characteristics of the battery in the charging and discharging processes more accurately, and are simple in structure and small in operation amount are urgently needed. Disclosure of Invention Aiming at the technical problems, the invention provides a sodium ion battery SOC accurate estimation method and a battery management system based on an improved aerodynamic model. The traditional aerodynamic model simulates the battery polarization effect only through the gas gap filling solubility, and is difficult to completely describe the voltage rebound characteristic related to the strong polarization reaction, so that a large error exists in the model. Therefore, the invention introduces the gas hydration solubility in the modeling and improves the aerohydrodynamic model, thereby more accurately representing the polarization dyna