Online collaborative estimation method for charge state and health state of ternary lithium battery

Abstract

The invention discloses an online collaborative estimation method for the charge state and the health state of a ternary lithium battery. The method improves the Thevenin equivalent circuit model, obtains the state space equation of the improved Thevenin equivalent circuit model according to the circuit relationship, further obtains the mapping relation between OCV and SOC, obtains the specific values of the polarization resistance, the polarization capacitance and the internal resistance at each sampling point by acquiring the external voltage and current values and performing identification in real time by using the FFRLS algorithm, the parameter values of the Thevenin equivalent circuit model are updated in real time according to the running state of the BMS immediately before the calculation of the SOC and the SOH each time, so that the prediction of the SOC and the SOH by the BMS is more accurate, when the method achieves high-precision estimation of the SOC and SOH for the ternary lithium battery, the external circuit is simple, only the conventional BMS is used for acquiring the voltage, current and time values, and the method has extremely strong convergence, has high robustness to the initial error value, and still adopts the iterative loop calculation method, so the sampling precision requirement of BMS can be properly reduced.

Description

technical field [0001] The invention relates to a method for estimating the state of charge and state of health of a battery, in particular to an online collaborative estimation method for the state of charge and state of health of a ternary lithium battery, belonging to the technical field of battery management. Background technique [0002] With the transformation of human energy consumption structure, renewable clean energy has attracted much attention. Among them, ternary lithium batteries have been widely used in pure electric vehicles and large-scale energy storage due to their advantages such as high energy density, long cycle life, safe use and low self-discharge rate. In this process, only by realizing good management of the battery can the battery work in an excellent state and at the same time prolong the service life of the battery. Therefore, how to quickly and accurately determine the working state (remaining power) and service life of the battery is one of th...

AI Technical Summary

Problems solved by technology

Although this method can complete the joint estimation of lithium battery SOC and SOH, the model parameters are obtained based on specific working conditions under off-line conditions. When the operating conditions and environment change, the model parameters cannot be updated in real time. Therefore, for different operating conditions The applicability to the environment is low, and the error is large

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