Method for calculating state of charge of battery in battery management system

Abstract

The invention discloses a method for calculating the state of charge of a battery in a battery management system, after starting and electrifying the battery management system, the method comprises the following steps: (1) calculating time interval t between startup at this time and shutdown at the last time; (2) judging time determined by the time interval t and total voltage of a battery pack; (3) calculating initial value of the state of charge SOC0 of the battery; and (4) calculating the state of charge SOC of the battery through a formula. With the adoption of the method for calculating the state of charge of the battery in the battery management system, the calculated value of SOC can achieve the precision of 5% when the actual value of the SOC is 30-70% and the precision of 3% when the actual value of the SOC is higher or lower, thereby being capable of better meeting the demands of actual use of new energy automobiles.

Description

technical field [0001] The invention relates to a battery management system of a new energy vehicle, in particular to a method for calculating the state of charge of a battery in the battery management system of a new energy vehicle. Background technique [0002] The current battery state of charge (State Of Charge, SOC) calculation method in the existing battery management system mainly focuses on pure current integration or look-up table method, that is, various data (including SOC-OCV curve, I-V curve, etc.) and store, and calculate the SOC by looking up the table on the basis of measuring the current and voltage, because the battery capacity itself is affected by many factors, such as charge and discharge efficiency, temperature, electrolyte density, self-discharge, aging, and internal resistance. ; Due to the influence of electrochemical polarization, the open circuit voltage measured online in real time is related to factors such as temperature and resting time, and is...

AI Technical Summary

Problems solved by technology

[0002] The current battery state of charge (State Of Charge, SOC) calculation method in the existing battery management system mainly focuses on pure current integration or look-up table method, that is, various data (including SOC-OCV curve, I-V curve, etc.) and store, and calculate the SOC by looking up the table on the basis of measuring the current and voltage, because the battery capacity itself is affected by many factors, such as charge and discharge efficiency, temperature, electrolyte density, self-discharge, aging, and internal resistance. ; Due to the influence of electrochemical polarization, the open circuit voltage measured online in real time is related to factors such as temperature and standing time, and is quite different from the actual open circuit voltage. Therefore, the accuracy of existing estimation methods is difficult to meet the requirements of new energy vehicles.

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