Estimating method for initial value of stage of charge of high-accuracy lithium ion battery

Abstract

The invention discloses an estimating method for the initial value of the stage of charge of a high-accuracy lithium ion battery and belongs to the technical field of automobile power batteries. The estimating method comprises the following steps: firstly, according to a corresponding relation curve of the open-circuit voltage and an SOC (Stage of Charge) at different temperatures, estimating an open-circuit voltage stage of charge (SOCocv) through the lookup table; secondly, according to standing time of the battery, the current voltage platform of the battery and the battery pack temperature, obtaining a power-on initial stage of charge through the three-dimensional lookup table; finally, according to the self-discharging characteristic of the battery, correcting the initial stage of charge. Through the adoption of the method disclosed by the invention, an accumulated error caused by inaccuracy of the initial value estimated through an ampere-hour integral method and the estimation error of stage of charge caused by static current loss in the shutdown process are effectively reduced on the basis of factors of the characteristics of the open-circuit voltage at different temperatures, the standing time of the battery, the self-discharging characteristics of the battery and the like, and the higher accuracy is achieved. The method is suitable for SOC initial value estimation of a single battery, a module and a battery assembly.

Description

technical field [0001] The invention belongs to the field of lithium battery management systems of new energy vehicles, and relates to a method for estimating the state of charge of lithium ion batteries. Background technique [0002] With the gradual deterioration of the global climate, the increase of urban air pollution and the excessive consumption of oil resources, more and more people in the automotive field are turning their attention to new energy vehicles. Lithium-ion batteries have excellent performances such as small size, high energy density, long storage life, no memory effect, high voltage and low self-discharge rate, and have gradually become the winners of new energy vehicle power batteries. Therefore, how to make good use of batteries has become a key technology in the field of batteries and their integration. Accurately monitoring the state of charge (SOC) of batteries has become a difficult and hot issue in the research of battery management systems and ev...

AI Technical Summary

Problems solved by technology

Among them, the ampere-hour integration method is the most common and simplest method, but the biggest disadvantage of the ampere-hour integration method in application is that it is greatly affected by the selection of the initial SOC value, and the initial value estimation is inaccurate, which causes the SOC estimation of the ampere-hour integration method to accumulate. error, which greatly reduces the applicability of the ampere-hour integration method

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