Method and system for estimating charge state of lithium ion power battery

Abstract

The invention discloses a method and a system for estimating the charge state of a lithium ion power battery. The method comprises the following steps: establishing a first-order RC equivalent circuitmodel of a battery, and establishing a state equation of the model; defining the state vector of the state equation, wherein the state vector comprises a model parameter of the model and an OCV valueof the battery; solving the expression of the coefficient matrix of the state equation according to the state vector; carrying out online identification of the model parameter and the OCV estimationvalue of a model through adopting the real-time working current of the battery as the system excitation, the real-time working voltage as an observed quantity and the extended kalman filtering algorithm; according to the OCV estimation value and the OCV-SOC relation curve of the battery, obtaining the SOC estimation value of the battery through the interpolation method. According to the invention,during the usage process of the battery, the parameter of the model can be identified in real time in the online manner, and the parameter of the model is corrected in real time. As a result, the OCVestimation value with high accuracy is estimated.

Description

Technical field [0001] The present invention relates to the technical field of lithium ion batteries, in particular to a method and system for estimating the state of charge of a lithium ion power battery. Background technique [0002] SOC, the full name is State of Charge, represents the state of charge, also called the remaining power, which represents the ratio of the remaining capacity of the battery after a period of time or long-term storage and its fully charged state. It is often expressed as a percentage. The SOC of lithium-ion batteries for new energy vehicles is a key parameter that cannot be directly measured. An accurate SOC estimate is the main basis for ensuring the use of lithium-ion batteries within the working range, and is also a prerequisite for improving lithium-ion battery life and energy utilization. The SOC estimation of lithium-ion batteries is also an important basis for vehicle energy and power matching and control, so it is of great significance to stu...

AI Technical Summary

Problems solved by technology

However, there are three disadvantages: first, the ampere-hour integration method can only solve the change of power within a period of time, and has a high dependence on the initial value; second, the cumulative error caused by the lack of accuracy of the current sensor cannot be corrected in real time; finally, When the battery management system is not working, the self-discharge effect of the battery cannot be estimated

The core idea of ​​the Kalman filt

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