Method and device for estimating battery pack SOC based on thevenin model

Abstract

The invention provides a Thevenin model-based battery pack SOC estimation method and device. The method comprises the steps of building a Thevenin equivalent circuit model of a to-be-estimated batterypack; determining a polarization effect parameter value of the Thevenin equivalent circuit model; determining an initial value of an extended Kalman filter and using the extended Kalman filter algorithm to determine an objective function between a time variable and a battery pack SOC variable based on the polarization effect parameter value and the initial value; estimating the SOC of the batterypack at a current time point according to the objective function. The method and the device can effectively improve the estimation precision of the SOC of a battery pack.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a method and device for estimating the SOC of a battery pack based on a Thevenin model. Background technique [0002] At present, a lot of research has been done on the accurate estimation of battery SOC at home and abroad. In related technologies, the commonly used method is still the combination of simple open circuit voltage method and ampere-hour integration method. The open circuit voltage method is to estimate the initial SOC value of the battery according to the static OCV data of the cell voltage look-up table when the battery management system is still and powered on again. The ampere-hour integration method is to integrate the charging and discharging current of the battery with respect to time, and estimate the dynamic SOC value of the battery. The open circuit voltage method requires the power battery to stand for a long enough time, which is obviously not easy to ...

AI Technical Summary

Problems solved by technology

The open circuit voltage method requires the power battery to stand for a long enough time, which is obviously not easy to achieve under working conditions

The ampere-hour integration method has high requirements for current sampling accuracy. If the power battery is charged and discharged at the high end of the SOC for a long time, large accumulated errors will occur.

In addition, the use range of SOC of automotive power batteries is generally between 30-70%. If there is no low-end correction for a long time, using the ampere-hour integration method will cause large errors

[0003] In these methods, the estimation error of the SOC of the battery pack is relatively large, and the accuracy is not high.

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