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Equivalent circuit lithium-ion battery model

Overview

Key features

About:ECM is an “equivalent circuit model” (ECM) representing the battery as a network of electronic components. This model predicts the battery current-voltage relation as a function of state-of-charge (SOC) and temperature. Battery properties depend on state-of-health (SOH) as defined by inputs for capacity fade and resistance increase. The model is capable of evaluating battery heat dissipation rate and battery temperature change in conjunction with a thermal model.

• Compatible with any thermal model
• Compatible with distributed electronic networks and 3D cell/module/pack models
• Compatible with user-defined inputs for capacity fade and resistance increase

Key applications

• Cell comparison and cell selection
• Rapid system prototyping
• Beginning-of-life and aged-cell scenario analysis
• Representation of cell performance in 3D thermal models

Technical Description

About:ECM solves Kirchhoff’s laws for the current-voltage relation of a network of electronic components. About:ECM is compatible with any specification of current, voltage or power load on the battery. Specifically, the equivalent circuit used is either a “1-RC pair” or “2-RC pair” circuit, depending on the cell. The circuits constitute (Figure 1) an open-circuit voltage source (Vsrc0) in series with a resistance (R0) and respectively one or two elements comprising a resistor and capacitor in parallel:

Figure 1: Schematic of a 2-RC pair circuit. The 1-RC pair circuit removes elements R2 and C2.

Mathematical Specification

Implementation Details