Constant Phase Element in the Time Domain: The Problem of Initialization

The constant phase element (CPE) is found in most battery and supercapacitor equivalent circuit models proposed to interpret data in the frequency domain. When these models are used in the time domain, the initial conditions in the fractional differential equations must be correctly imposed. The ini...

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Main Authors: Juan Antonio López-Villanueva, Salvador Rodríguez Bolívar
Format: Article
Language:English
Published: MDPI AG 2022-01-01
Series:Energies
Subjects:
Online Access:https://www.mdpi.com/1996-1073/15/3/792
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author Juan Antonio López-Villanueva
Salvador Rodríguez Bolívar
author_facet Juan Antonio López-Villanueva
Salvador Rodríguez Bolívar
author_sort Juan Antonio López-Villanueva
collection DOAJ
description The constant phase element (CPE) is found in most battery and supercapacitor equivalent circuit models proposed to interpret data in the frequency domain. When these models are used in the time domain, the initial conditions in the fractional differential equations must be correctly imposed. The initial state problem remains controversial and has been analyzed by various authors in the last two decades. This article attempts to clarify this problem by proposing a procedure to prepare the initial state and defining a decay function that reveals the effect of the initial state in several illustrative examples. This decay function depends on the previous history, which is reflected in the time needed to prepare the initial state and on the current profile assumed for this purpose. This effect of the initial state is difficult to separate and can lead to the misinterpretation of the CPE parameter values.
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spelling doaj.art-587e74bb105748a4b99f7d22871e86802023-11-23T16:19:59ZengMDPI AGEnergies1996-10732022-01-0115379210.3390/en15030792Constant Phase Element in the Time Domain: The Problem of InitializationJuan Antonio López-Villanueva0Salvador Rodríguez Bolívar1Department of Electronics and Computer Technology, CITIC, University of Granada, 18071 Granada, SpainDepartment of Electronics and Computer Technology, CITIC, University of Granada, 18071 Granada, SpainThe constant phase element (CPE) is found in most battery and supercapacitor equivalent circuit models proposed to interpret data in the frequency domain. When these models are used in the time domain, the initial conditions in the fractional differential equations must be correctly imposed. The initial state problem remains controversial and has been analyzed by various authors in the last two decades. This article attempts to clarify this problem by proposing a procedure to prepare the initial state and defining a decay function that reveals the effect of the initial state in several illustrative examples. This decay function depends on the previous history, which is reflected in the time needed to prepare the initial state and on the current profile assumed for this purpose. This effect of the initial state is difficult to separate and can lead to the misinterpretation of the CPE parameter values.https://www.mdpi.com/1996-1073/15/3/792constant phase element (CPE)fractional calculustime domaininitial conditionsZARCsupercapacitor and battery modeling
spellingShingle Juan Antonio López-Villanueva
Salvador Rodríguez Bolívar
Constant Phase Element in the Time Domain: The Problem of Initialization
Energies
constant phase element (CPE)
fractional calculus
time domain
initial conditions
ZARC
supercapacitor and battery modeling
title Constant Phase Element in the Time Domain: The Problem of Initialization
title_full Constant Phase Element in the Time Domain: The Problem of Initialization
title_fullStr Constant Phase Element in the Time Domain: The Problem of Initialization
title_full_unstemmed Constant Phase Element in the Time Domain: The Problem of Initialization
title_short Constant Phase Element in the Time Domain: The Problem of Initialization
title_sort constant phase element in the time domain the problem of initialization
topic constant phase element (CPE)
fractional calculus
time domain
initial conditions
ZARC
supercapacitor and battery modeling
url https://www.mdpi.com/1996-1073/15/3/792
work_keys_str_mv AT juanantoniolopezvillanueva constantphaseelementinthetimedomaintheproblemofinitialization
AT salvadorrodriguezbolivar constantphaseelementinthetimedomaintheproblemofinitialization