SOC online estimation method based on piecewise correction of model parameters

Abstract

The invention discloses a lithium battery SOC online estimation method based on piecewise correction of model parameters, which is characterized in that a three-dimensional off-line model is built according to the battery temperature, the battery internal resistance and an SOC true value under a battery working current condition; and performing piecewise elimination on an accumulated error of an SOC estimated value acquired according to an ampere-hour integration method on the basis of the SOC true value of the three-dimensional off-line model, and finally acquiring an SOC corrected value. According to the invention, an accumulated error of the ampere-hour integration method can be significantly eliminated, and the SOC online estimation precision is improved.

Description

technical field [0001] The invention relates to the field of battery management systems for electric vehicles, in particular to an online SOC estimation method for lithium batteries. Background technique [0002] In recent years, with the deteriorating air quality and the scarcity of oil resources, new energy vehicles, especially pure electric vehicles, have become the development hotspots of major automobile companies in the world today. The power battery pack is a key component of an electric vehicle. The power battery SOC is used to directly reflect the remaining power of the battery. It is an important basis for the vehicle control system to formulate an optimal energy management strategy. Accurate estimation of the power battery SOC value is important for improving battery safety and reliability. It is of great significance to improve battery energy utilization and prolong battery life. [0003] Overall, SOC online estimation techniques are divided into two categories....

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Problems solved by technology

[0004] The first type of method is simple in principle, but has strong limitations in the actual application process. For example, the open circuit voltage method can only be used for offline estimation, and the cumulative error of the ampere-hour integration method is inevitable.

The advantage of the second type of method is that the online estimation accuracy is high and has good robustness, and the accuracy of the measurement components is not too high. The disadvantage is that it relies heavily on the accuracy of the battery model, requires a large number of mathematical operations, and the algorithm is portable. Poor sex

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