Cell state-of-charge estimation method and battery management system of power battery

Abstract

The invention relates to the technical field of automobile power batteries, provides a cell state-of-charge estimation method of a power battery and a battery management system, and solves the problems of low precision and low calculation speed when the SOC of a battery cell of the power battery is estimated in the prior art. The cell state-of-charge estimation method of the power battery comprises the following steps: acquiring parameters in a preset cell equivalent circuit model, load current and terminal voltage of each cell; according to parameters in the preset cell equivalent circuit model, load current and cell reference voltage, utilizing an EKF algorithm to determine cell reference SOC and cell average open-circuit voltage, and determining the cell reference voltage by terminal voltage of a cell in the power battery; according to the parameters in the preset cell equivalent circuit model, the terminal voltage of each cell, the cell reference voltage and the cell average open-circuit voltage, determining the SOC deviation of each battery cell by using an RLS algorithm; and obtaining an SOC estimated value of each battery cell of the power battery according to the sum of theSOC deviation of each battery cell and the battery cell reference SOC.

Description

technical field [0001] The invention relates to the technical field of automotive power batteries, in particular to a method for estimating the state of charge of a battery cell of a power battery and a battery management system. Background technique [0002] SOC (State of Charge) directly reflects the remaining power of the power battery and is the primary parameter for battery management of electric vehicles. The SOC estimation method for the power battery in the prior art includes the extended Kalman filter algorithm (EKF), which is a state estimation algorithm, and the power battery is regarded as a dynamic system, and the SOC is an internal state variable of the system. However, since the power battery is usually a series connection of multiple cells, the general algorithm is to apply the EKF algorithm to estimate the SOC only for the cells corresponding to the highest and lowest terminal voltages, but it cannot estimate the SOC of all cells. If EKF is used to estimate ...

AI Technical Summary

Problems solved by technology

However, since the power battery is usually a series connection of multiple cells, the general algorithm is to apply the EKF algorithm to estimate the SOC only for the cells corresponding to the highest and lowest terminal voltages, but it cannot estimate the SOC of all cells. If EKF is used to estimate the SOC of each cell separately The SOC of a battery cell, the calculation load may reach the order of 10ms, and the calculation complexity is high.

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