State of charge estimation method and state of charge estimation system for lithium battery of electric vehicle

Abstract

The invention relates to a state of charge estimation method and state of charge estimation system for the lithium battery of an electric vehicle. The state of charge estimation method includes the following steps that: the voltage of each battery is acquired in real time during charging and discharging; charging and discharging operations of different rates are performing separately a preset number of times, so that an initial charging and discharging rate curve showing a relationship between the voltage and the state of charge of the battery under the different rates can be obtained; a current average value and a battery voltage average value during a period of time are calculated; the proportional position of the current average value in an interval to which the current average value belongs is calculated; and a current charging and discharging rate curve is synthesized according to the proportional position; a table read battery remaining capacity corresponding to a current voltageis obtained, and an integral battery remaining capacity is obtained by means of charge integration, an error scale factor is calculated, and a current battery remaining capacity is calculated. With the method and the system of the present invention adopted, a complicated battery model is not required, the state of charge of a lithium battery pack, especially a ternary lithium battery pack, can beaccurately and accurately estimated, and the method and system are also effective under a condition that a lithium battery pack is aged.

Description

technical field [0001] The present application relates to the field of state of charge of lithium batteries for electric vehicles, in particular to a state of charge estimation method and a state of charge estimation system for lithium batteries of electric vehicles. Background technique [0002] In order to cope with the energy crisis and slow down global warming, many countries have begun to attach importance to energy conservation and emission reduction and the development of low-carbon economy. Because electric vehicles are driven by electricity, they can reduce carbon dioxide emissions or even achieve zero emissions, so they have attracted the attention of various countries and developed rapidly. However, the cost of batteries is still high, and the performance and price of power batteries are the main "bottleneck" for the development of electric drive vehicles. [0003] With the development of electric vehicles, battery management systems (BATTERY MANAGEMENT SYSTEM, B...

AI Technical Summary

Problems solved by technology

The open-circuit voltage method needs to let the battery stand for more than 1 hour to restore the battery terminal voltage to the open-circuit voltage, which is not real-time; the ampere-hour measurement method needs to accurately know the initial capacity of the battery, and there is a cumulative error; the artificial neural network method and Kalman The filtering method requires accurate mathematical models and strong data processing capabilities, which is very difficult to implement, and the accuracy is greatly affected by the battery model

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