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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 

Please note: Until further notice, there is no consultation hour with personal contact. Please phone me or write me an email.

The consultation hours on December 21 and 28 are cancelled.


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)


A high frequency model for predicting the behavior of lithium-ion batteries connected to fast switching power electronics
Citation key KorthPereiraFerraz201840
Author Pablo Korth Pereira Ferraz and Robert Schmidt and Delf Kober and Julia Kowal
Pages 40 - 49
Year 2018
ISSN 2352-152X
DOI https://doi.org/10.1016/j.est.2018.04.024
Journal Journal of Energy Storage
Volume 18
Abstract Abstract Battery powered energy systems such as electric vehicles utilize power electronics for controlling energy flows between the battery and the load or generation, respectively. Therefore, the battery is under high frequency stress due to fast switching power electronic devices. However, most battery models throughout the literature are not able to cope with high frequency excitation. This paper proposes an easy to implement equivalent circuit model that covers aforementioned frequency regions with a series of inductors that are each connected in parallel with an ohmic resistance. This circuit is parameterized by electrochemical impedance spectroscopy (EIS) up to 100 kHz. For further regions that reach regions of megahertz a skin effect model is investigated and compared to the RL-model. It is shown that such semi-empirical models can be motivated by geometrical considerations that can be found in the literature. Moreover, the proposed model is validated by simulating the voltage response from an input current that originates from an actual back-to-back half bridge DC/DC converter. The promising results indicate that such models might be implemented in future battery energy systems to improve insights on how batteries react to perturbations such as \EMI\ noise or high frequency current ripple.
Link to publication Download Bibtex entry

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Auxiliary Functions


Technische Universität Berlin
Electrical Energy Storage Technology
Institute of Energy and Automation Technology
Faculty IV
sec. EMH 2
Einsteinufer 11
D-10587 Berlin


Sec. EMH2
Room EMH 162
+49 (0)30 314-21633
+49 (0)30 314-21133