Abstract
This contribution deals with the control of a battery emulator used in automotive testbeds for electric drivetrains. The battery emulator, which is realized as a DC-DC converter, is connected to a unit-under-test (UUT), e. g., an electric motor inverter. To accurately emulate the dynamic impedance of a battery, a highly dynamic output is required. Additionally, battery emulators should be applicable for a large variety of UUTs, hence robust performance in a large operating range is also required. This is especially challenging when the UUT behaves like a constant power load, as this can cause stability issues. To meet the requirements, a flatness-based control concept is presented that establishes feedback equivalence between a nonlinear and a linearized system representation. By examining the stability of the concept, an estimation of the region of attraction is found.
Zusammenfassung
Dieser Artikel beschreibt die Regelung eines Batterie-Emulators, welcher in Fahrzeugprüfständen für elektrische Antriebe verwendet wird. Der als DC-DC Konverter realisierte Emulator wird mit einem Prüfling verbunden, z. B. einem E-Motor-Inverter. Um das dynamische Verhalten einer Batterie wiedergeben zu können, muss der Ausgang hochdynamische Spannungsverläufe realisieren können. Zum Testen einer weiten Bandbreite von Prüflingen, sollte der Batterie-Emulator einen großen Arbeitsbereich vorweisen. Schwierig ist dies, wenn der Prüfling sich wie eine Last mit konstanter Leistungsaufnahme verhält, was zu Stabiltätsproblemen führen kann. Um dies dennoch zu bewältigen, stellt der präsentierte Flachheits-basierende Regler Rückführäquivalenz zwischen einer nichtlinearen und einer linearisierten Modellbeschreibung her. Des Weiteren wird mittels einer Stabilitätsanalyse eine Abschätzung des Einzugsbereiches angegeben.
Funding statement: The financial support by the Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology and Development, and the Christian Doppler Research Association is gratefully acknowledged.
About the authors
Michael Zauner was born in Baden, Austria in 1990. He received the Dipl. Ing. degree from TU Wien, Vienna, Austria, in 2018. Since 2018, he has been a Project Assistant at the Institute of Mechanics and Mechatronics at TU Wien. His current research interests include optimization, nonlinear control, and digital systems.
Philipp Mandl was born in Mistelbach, Austria, in 1996. He received the B.S. degree in mechanical engineering from the TU Wien, Vienna, Austria, in 2019, where he is currently working toward the M.S. degree in mechanical engineering. His current research interests include power system modeling, nonlinear control and digital systems.
Oliver König received the M.S. degree from Graz University of Technology, Austria, in 2009. Starting from 2010, he was working at the Institute of Mechanics and Mechatronics at TU Wien, Austria, from where he received the Ph.D. degree in 2013. In 2013 he joined AVL List GmbH in Graz to work on digital control for automotive electrification test systems. In 2019, he became department manager responsible for control systems in the segment of Energy Storage Test and Emulation Products. His main area of research is embedded model predictive control with a focus on power electronics.
Christoph Hametner received the M.S. degree in mechanical engineering, the Ph.D. degree in technical sciences, and the Habilitation (professorial qualification) in control theory and system dynamics from TU Wien, Vienna, Austria, in 2005, 2007, and 2014, respectively. He is the Head of the Christian Doppler Laboratory for Innovative Control and Monitoring of Automotive Powertrain Systems, TU Wien. His research interests are nonlinear system identification, modeling, and control.
Stefan Jakubek received the M.S. degree in mechanical engineering in 1997, the Ph.D. degree in technical sciences, in 2000, and the Habilitation (professorial qualification) in control theory and system dynamics in 2007, all from TU Wien, Vienna, Austria. From 2006 to 2009, he was the Head of Development for Hybrid Powertrain Calibration and Battery Testing Technology with AVL List GmbH, Graz, Austria. He is currently a Professor with the Institute of Mechanics and Mechatronics, TU Wien. His research interests include fault diagnosis, nonlinear system identification, and simulation technology.
Appendix A Flatness property of Σ n l
The output y and its time-derivatives of the nonlinear system
From (32)–(36) one can see that when
Remark.
The singularity at
Remark.
The flatness property of
Appendix B Nominal Lyapunov function change
The matrix
The state-feedback gain
Inserting (20) into
where
which is negative definite.
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