Electrochemical process-based lithium ion battery equivalent model in full SOC range

Abstract

The invention provides an electrochemical process-based lithium ion battery equivalent model in a full SOC range, and relates to the field of lithium ion battery equivalent models. The model comprises a lithium ion battery real-time SOC simulation model composed of capacitors Ccapacity, Cds1 and Cds2, resistors Rds1 and Rds2, a first current source and a second current source, and a lithium ion battery terminal voltage response simulation model composed of two capacitors Cdl and Cconc, an impedance Zctr, a voltage source UOCV and a terminal voltage Ut. Ut is equal to UOCV (USOC_surf)-IRohm-eta ctr-eta conc. The model is high in simulation precision in the full SOC range of the lithium battery, is high in calculation efficiency, avoids the solving of a partial differential equation, and is more suitable for being applied to a BMS.

Description

technical field [0001] The invention relates to the field of equivalent models of lithium-ion batteries, in detail, it is a full-SOC range lithium-ion battery based on electrochemical processes that can provide high simulation accuracy in the full SOC range of the battery, especially in the low SOC range. effective model Background technique [0002] We know that with the increase in the number of electric vehicles, the endurance of power batteries has received widespread attention. On the one hand, it is necessary to conduct research on the battery itself to increase the energy density of the power battery; on the other hand, it is necessary to formulate a more efficient energy management strategy. With the advantages of relatively high energy density and long cycle life, lithium batteries have become the main energy storage unit of current electric vehicles. In order to ensure the safe and efficient operation of the on-board energy system of electric vehicles, the batter...

AI Technical Summary

Problems solved by technology

Taking the most widely used second-order RC equivalent circuit model as an example to analyze the error source of the model: although the two RC modules used to simulate the internal polarization process of the battery have differences in time constants, their effects on the terminal voltage are parallel No matter through offline identification or online identification, it is obtained at the same time, and there is no obvious correspondence with the internal electrochemical process of lithium-ion batteries.

At the same time, the charge transfer reaction occurring at the solid-liquid interface inside the lithium battery is not purely resistive, so the second-order RC equivalent circuit model uses a resistance to describe this process, which will produce a large error

In addition, the solid-state diffusion process of lithium ions inside the lithium battery will affect the real-time OCV of the battery in the working state, and the second-order RC equivalent circuit model uses the macroscopic average SOC to determine the OCV of the battery, so that the model is at low SOC Less accurate simulation in range

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