Pulse Width Selection Method for High Accuracy State of Charge Estimation

Abstract

The invention relates to the electric vehicle battery power field, and has good state of charge (SoC) estimation precision facing variable current. Therefore the invention adopts the technical scheme of a pulse width selection method applied to high precision SoC estimation. The pulse width selection method applied to the high precision SoC estimation includes the steps of: measuring a group of pulse responses corresponding to various battery SoC levels and storing the pulse responses in a lookup table by using the pulse width satisfying the following formula under an experiment condition of off-line calibration, namely dividing the total range of the SoC values of valid battery in the batteries into n independent values, each value being corresponding to one determined pulse response hn[k]; finishing the lookup table of the pulse responses, comparing a measurement value of a terminal voltage with a convolution value calculated by the pulse responses in the lookup table, and determining the battery SoC of the battery in this condition. The pulse width selection method applied to the high precision state of charge estimation is mainly applied to the electric vehicle battery power measuring field.

Description

technical field [0001] The invention relates to the field of electric vehicle battery power, in particular to the problem of estimating the state of charge of a power lithium battery when it is in use. Specifically, it relates to a pulse width selection method applied to high-precision state-of-charge estimation. technical background [0002] In recent years, in order to solve the dual problems of energy and environment, electric vehicles with low emission and low noise have become the focus of attention of major automobile manufacturers. In the power management system of electric vehicles, the state of charge (SoC, State of Charge) of the battery is a very important key parameter, because it represents the amount of remaining energy stored in the battery. Generally speaking, keeping the SoC of the lithium-ion battery within an appropriate range, such as 20% to 95%, is beneficial to protect the functional integrity of the battery. [0003] The open-circuit voltage method i...

AI Technical Summary

Problems solved by technology

The open circuit voltage method needs to undergo a static storage process for the battery pack to achieve internal equilibrium, so it cannot be applied to dynamic environments such as electric vehicles

The state of charge estimation method based on the impulse response indirectly applies the open circuit voltage method in the use of the battery, but in the face of changing current, the accuracy of this method is low, and the estimation error of the state of charge is large

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