SOC online estimation method for storage battery based on EKF algorithm

Abstract

The invention provides an SOC online estimation method for a storage battery based on an EKF algorithm, and the method comprises the following steps: determining a battery equivalent circuit model, and building a discrete state space model of a battery nonlinear system; building a fitting function relation between the SOC initial value SOC(0) of the battery and an open-circuit voltage initial value UOC(0) through a constant current charging and discharging experiment, solving and obtaining the SOC initial value SOC(0) of the battery; taking SOC(0) as an initial state quantity of input, carrying out the estimation of the SOC of the battery through the EKF algorithm, and generating an SOC estimated value; carrying out the temperature, battery service life and self-discharging effect compensation for the generated SOC estimated value, and outputting a corrected SOC estimated value. Through the optimization of the SOC initial value, the method enables the initial state of the EKF to approach to the real-time state of the storage battery as much as possible, guarantees the convergence speed of the SOC online estimation of the storage battery, and improves the estimation precision through the temperature, battery service life and self-discharging effect compensation.

Description

technical field [0001] The invention belongs to the technical field of electric vehicle power batteries, and in particular relates to an online SOC estimation method of a storage battery based on an EKF algorithm. Background technique [0002] Batteries are the main energy carrier and power source of electric vehicles, and are also the main component of the vehicle body of electric vehicles. The performance of batteries determines the safety, reliability and efficiency of electric vehicle systems. Accurate prediction of battery SOC (State of Charge, battery state of charge) can not only improve the capacity utilization efficiency of the battery, but also avoid damage to the battery due to overcharging and overdischarging of the battery, and prolong the service life of the battery. However, due to the complex electrochemical properties and physical reactions inside the battery, SOC cannot be directly measured, and is generally estimated through measurable parameters such as v...

AI Technical Summary

Problems solved by technology

However, in EKF estimation, the selection of the initial value of the battery SOC affects the convergence speed of the estimation curve, so the selection of the initial value of the battery SOC cannot be ignored

At the same time, the accuracy of battery SOC estimation results is affected by factors such as temperature, battery life, and battery self-discharge effects.

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