Battery SOC (state of charge) estimation method based on polarization voltage recovery characteristics

Abstract

The invention discloses a battery SOC (state of charge) estimation method based on polarization voltage recovery characteristics. The method comprises two parts: analysis of battery polarization voltage characteristics and SOC estimation based on polarization voltage recovery characteristics, wherein in the first part, based on the battery standing voltage curves under different battery SOC, the battery residual polarization voltage in different standing time is extracted, the maximum battery voltage deviation allowable at the SOC error of 3% or below is derived from the OCV-SOC curve, and theminimum standing time for eliminating polarization voltage under different SOC is obtained while guaranteeing the SOC error of 3%; in the second part, according to the battery minimum standing time under different SCO of the same-batch batteries and the law of aging with time, a response surface model is adopted as an approximate model, and an accurate approximation function relationship is obtained in a local scope by using a few data points, so as to obtain the minimum standing time that guarantees the SOC error being within 3% in the whole life cycle of the battery; corresponding battery SOC is estimated according to whether the standing time reaches the minimum standing time.

Description

technical field [0001] The invention belongs to the technical field of electric vehicles, and in particular relates to a method for estimating the state of charge of a power battery of an electric vehicle. Background technique [0002] Accurately estimating the state of charge (SOC) of the battery is conducive to improving the overall performance of the battery management system and ensuring the cruising range of electric vehicles. At present, battery SOC estimation methods include ampere-hour integral method, open circuit voltage method, Kalman filter method, neural network method and fuzzy control algorithm, etc. Among them, the ampere-hour integration method has also been widely used in battery management systems due to its high calculation efficiency, but the biggest defect of this method is that in practical applications, the initial value of SOC cannot be determined due to capacity decay due to battery self-discharge and aging. There are also cumulative errors of inte...

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Problems solved by technology

The open circuit voltage method needs to stand for a long time or establish a corresponding mathematical description equation based on the battery physical or electrochemical model to identify it, but it takes a long time to stand for a long time and is not suitable for online applications; while the open circuit voltage identified by the battery model Restricted by the accuracy of the battery model used, at the same time, due to the large amount of calculation, the system processor speed is required to be high

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