TU Berlin

Electrical Energy Storage TechnologyChair

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Prof. Dr.-Ing. Julia Kowal

Julia Kowal

Room: EMH 163


Einsteinufer 11

Sec. EMH 2

10587 Berlin

Phone: +49 (0)30 314-25394

Fax:     +49 (0)30 314-21133


Consultation hours: On Mondays 9 - 10 h and on appointment. In summer semester 2022 (25.4.-18.7.), the consultation hour will be from 10-11 h.

In most weeks, I am in the office on mondays, so a personal meeting is possible again. To be sure, please ask before you come. Alternatively, you can phone me or we can arrange a Zoom meeting.


since 03/2014
Chair of Electrical Energy Storage Technology at the TU Berlin
01/10 - 02/14
Senior engineer at the department of Electrochemical Energy Conversion and Storage Systems, ISEA, RWTH Aachen
PhD at RWTH Aachen, Topic: "Spatially-resolved impedance of nonlinear inhomogeneous devices - using the example of the lead-acid battery"
Visiting researcher at the company Exide in Azuqueca de Hénares, Spain
Visiting Researcher at the research centre RISØ in Roskilde, Denmark
Research assistant at the department of Electrochemical Energy Storage Conversion and Systems at the Institute For Power Electronics and Electrical Drives (ISEA), RWTH Aachen
Studies of electrical engineering at RWTH Aachen Diploma thesis: "Investigation of the thermal behaviour of electrochemical energy storage systems in vehicle on-board power supplies"



Awards and Scholarships
Herbert-Kind-Price of ETG in the VDE
Brigitte-Berkenhoff-Price for the best graduate in the field of electrical engineering at RWTH Aachen
Aachen's VDE price
Sponsorship through the Prof. Dr. Koepchen Merit Foundation (RWE)


Novel method for the parameterization of a reliable equivalent circuit model for the precise simulation of a battery cell's electric behavior
Citation key BRUCH2021229513
Author Maximilian Bruch and Lluis Millet and Julia Kowal and Matthias Vetter
Pages 229513
Year 2021
ISSN 0378-7753
DOI https://doi.org/10.1016/j.jpowsour.2021.229513
Journal Journal of Power Sources
Volume 490
Abstract This article presents a novel approach to extract the equivalent circuit model parameter from a pulse test. The presented results corroborate that this novel heuristic methodology can very accurately fit the voltage response of the battery, while drastically reducing the dependence of the parametrization on set boundary conditions and initial guess values. The method's robustness is verified by fitting the voltage response of a mock battery model with pre-defined parameters. It could be shown that the suggested method is able to precisely extract the set parameters from the simulated voltage. Furthermore, the model values obtained from the test of a lithium ion battery cell correlate with physical parameter and other investigation methods like the calculation of the distribution of relaxation times (DRT). As a result, an accurate equivalent circuit model of the cell was created. The restriction as to universal validity of the empirical equivalent circuit model was significantly reduced by limiting the voltage of the RC element with highest time constant. Finally, a robust battery cell model with only a minor root-mean-square error of 1.30% was obtained. Result A new method for the precise parameterization of an equivalent circuit model from pulse tests is presented. The robustness of such equivalent circuit models is increased by limiting the voltage of the RC element with the highest time constant. Overall, a precise, reliable model of a lithium-ion battery cell is created.
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