Detection method of state of charge difference of battery cells in hybrid electric vehicles

Abstract

The invention provides a method for detecting state-of-charge differences of battery cells of a hybrid electric vehicle. The method comprises the following steps of controlling a battery pack of the hybrid electric vehicle to enter a specific state from a conventional state; recording voltages Ui,t of all battery cells at all moments in the specific state, calculating an average voltage Um,t of all the battery cells at all the moments, further calculating the voltage differences deltaUi,t=Ui,t-Um,t of all the battery cells at all the moments, then carrying out average on the voltage differences delta Ui,t of all the battery cells to time t to obtain the open-circuit voltage difference of each battery cell, and obtaining a corresponding relation curve of the state-of-charge differences of the battery cells and the open-circuit voltage differences of the battery cells in the specific state; interpolating the open-circuit voltage differences of all the battery cells to the corresponding relation curve of the state-of-charge differences of the battery cells and the open-circuit voltage differences of the battery cells in the specific state, and obtaining the state-of-charge differences of the battery cells through querying. According to the method for detecting the state-of-charge differences of the battery cells of the hybrid electric vehicle, the identification of the state-of-charge differences of the battery cells is achieved directly, and health conditions of the battery pack can be further monitored.

Description

technical field [0001] The invention belongs to the technical field of power batteries for vehicles, and in particular relates to a method for detecting differences in state of charge of battery cells of a hybrid electric vehicle. Background technique [0002] The depletion of fuel and the deterioration of the environment make traditional fuel vehicles face the pressure of energy saving and emission reduction. As a transition between traditional fuel vehicles and pure electric vehicles (Electric Vehicle, EV), hybrid electric vehicles are widely accepted by the market due to their high fuel economy and environmental friendliness. A typical hybrid electric vehicle (Hybrid Electric Vehicle, HEV) usually mixes fuel-engine and battery-motor power sources, and the battery-motor power source is usually used as an auxiliary power source. And the power type LiFePO 4 Batteries are attracting more and more attention as an auxiliary power source energy storage device for hybrid electr...

AI Technical Summary

Problems solved by technology

In this case, with a measurement error of 5mV by the battery management system, the 5 cells with a state of charge from 40% to 60% are almost indistinguishable

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