A method of battery pack SOC estimation based on imm-ekf

Abstract

The invention discloses a method for estimating an SOC of a battery pack based on IMM-EKF. The method comprises the following steps: establishing a maximum monomer voltage interaction model, a minimummonomer voltage interaction model and an average voltage interaction model according to the voltage of the battery pack; respectively estimating the SOCs of the maximum monomer voltage interaction model, the minimum monomer voltage interaction model and the average voltage interaction model by virtue of an IMM-EKF filtering program; and calculating information distribution factors of each model,and carrying out probability fusion on the SOC of each model according to each information distribution factor, so as to obtain the integral SOC of the battery pack. According to the method, the battery pack is divided into three models, the SOC of each model is subjected to probability fusion according to the information distribution factors, and the high-precision integral SOC of the battery pack is obtained, so that the problem of large estimation errors of a single model is solved. The invention simultaneously provides a system for estimating the SOC of the battery pack based on the IMM-EKF. The system has the beneficial effects.

Description

technical field [0001] The present application relates to the technical field of electric vehicles, in particular to a method and system for estimating the SOC of a battery pack based on IMM-EKF. Background technique [0002] The battery management system (Battery Management System, BMS) is an important part of electric vehicles. The estimation of the battery state of charge (State of Charge, SOC) is the core of the battery management system. SOC represents the remaining capacity of the battery and its full state of charge. The ratio of the capacity, the accuracy directly affects the service life of the battery, safety performance, balance control and customization of thermal management strategies, so accurate SOC estimation is extremely important for BMS. [0003] Due to the voltage and energy requirements during the driving of electric vehicles, the battery management system needs to connect hundreds of single batteries in series or in parallel. However, due to the differ...

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Problems solved by technology

However, due to the difference in materials in the battery production process and the change of battery parameters in the process of charging and discharging, there will be a certain degree of inconsistency among the battery cells in the same battery pack, which will lead to differences in the SOC of each battery cell. The overall SOC of the battery pack is difficult to estimate

[0004] In the prior art, the minimum SOC or average SOC is usually used to replace the overall SOC for the overall SOC estimation of the battery pack. If the minimum SOC is used as the overall SOC, the overall battery pack will be overcharged, or the voltage of the battery cell will reach the charging cut-off point. When the SOC of the battery pack is not 100%; if the average SOC is taken as the overall SOC, with the use of the battery pack, the consistency of the battery will deteriorate, and the problem of overcharging or over-discharging of the battery cells will also occur.

[0005] Another estimation method in the existing algorithm is to estimate the entire group of batteries as a large single battery, but the interior of this "big battery" is more complicated, and it is more difficult to model than a single battery, and the entire group The consistency of is worse than the consistency between monomers, and it is more difficult to estimate

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