Online estimation method for direct current resistance of power battery of electric vehicle

Abstract

The invention relates to an online estimation method for direct current resistance of a power battery of a plug-in hybrid electric vehicle or a pure electric vehicle. The online estimation method includes that in the process of charging through a vehicle-mounted charger, charging to appointed equally spaced SOC points in sequence in a constant-current charging mode, and then using a constant-voltage charging mode; when the current is reduced to an equalizing current designed by a monomer equalizer, casually opening and closing the equalizer of each monomer in sequence, using the equalizer to generate a composite pulse excitation on each monomer, recording the change curve of the terminal voltage thereof changed along with the time, substituting into a corresponding mathematical model of direct current resistance of the power battery to obtain the direct current resistance and open-circuit voltage of the battery, and calculating the direct current resistance and open-circuit voltage of a power battery pack according to the direct current resistance and open-circuit voltage of the battery. The online estimation method for the direct current resistance of the power battery of the electric vehicle is simple and reliable and has high practicability and performability.

Description

technical field [0001] The invention relates to an online estimation method for the DC impedance of a power battery pack of an electric vehicle, and belongs to the field of electric energy management of the power battery of an electric vehicle. Background technique [0002] The power battery is an important part of the electric vehicle. During its use, accurate control of the state parameters of the power battery plays a vital role in improving the performance and safety of the electric vehicle. At present, some state parameters of power batteries such as state of charge (state of charge, SOC), state of health (state of health, SOH) and state of power (state of power, SOP) cannot be obtained directly through sensors or other devices, and need to contact power The electrical characteristic parameters of the battery are estimated in real time by using certain mathematical methods. [0003] The most important electrical characteristic parameters that are difficult to obtain di...

AI Technical Summary

Problems solved by technology

However, with the increase of battery life and the frequent acceleration, deceleration, start-stop and other complex operating conditions in the actual operation of electric vehicles, the DC internal resistance of the power battery pack will change to a certain extent. Considering the time-varying nature of the parameters, the accuracy of the corresponding state parameter estimation is also gradually reduced

However, there is no method to accurately predict the DC internal resistance and open circuit voltage of power battery packs online at home and abroad.

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