Kolloquiumsvortrag: Prof. Domenico Casadei, IEEE Fellow, University of Bologna

05.05.2014 von 17:15 bis 18:30

Institut für Elektrotechnik und Informationstechnik, Kaiserstr. 2, Raum: "Aquarium" Geb. D

Titel: "Multiphase power converters"


The use of multi-phase electrical drives has been widely recognized as a viable approach to obtain high power ratings without increasing the stator current per phase, making it possible to use standard power switches based on a single device.


The interest in multiphase drives is motivated also by their greater number of degrees of freedom in comparison with three-phase machines. Using these degrees of freedom it is possible to increase the torque density of the machine, to drive multi-motor drives, to preserve a correct behavior of the machine in case of fault and to estimate some machine parameters without the need of high frequency injection.  


In order to analyze the control strategies for multi-phase systems it is firstly necessary to introduce the space vector representation in multiple a-b planes (Multiple Space Vectors representation). It can be verified that it is not possible to analyze multi-phase systems using the space vector representation in a single a-b plane as it is for three-phase systems. As a second step, the modulation strategies for multi-phase converters should be investigated considering both SVM and PWM  techniques. For three-phase VSIs, the equivalence of the two methods has been proved, and they can be interchangeably implemented. On the contrary, in the case of multiphase VSIs, the carrier-based PWM method seems the most feasible, due to its inherent simplicity. The reason is that PWM focuses the attention on the control of each inverter branch, and this task is relatively simple if compared with the aim of SVM, i.e., the determination of the switching pattern, which involves all the branches of the inverter.


In order to fully exploit the potential of the carrier–based PWM technique and the multiple space vector representation, the lecture is focused on the Duty-Cycle Space Vector (DCSV) approach, which has the advantage of an effective and compact formulation.




Domenico Casadei received the Master Degree (with honors) in electrical engineering from the University of Bologna, Italy. From 1975 to 1985 he was a Research Assistant, and from 1985 to 2000 Associate Professor at the same University. Since 2001 he is full Professor of Electrical Drives at the University of Bologna. His current research interests include direct torque control and vector control of induction machines, multi-phase machines, multi-level converters, multi-phase converters, matrix converters, renewable energy systems, and diagnosis of electrical machines. He has published more than 220 papers in technical journals and conference proceedings.


He served as Head of the Electrical Engineering Department of the University of Bologna from 2004 to 2010. Currently, he is the Director of the PhD School of Electrical Engineering at the University of Bologna, Director of ”LEMAD” Laboratory of Electrical Machines and Drives, University of Bologna, and President of CMAEL Association of Italian Professors in Power Electronics, Electrical Machines and Drives


He has been elevated to the grade of IEEE Fellow for contributions to direct torque control and matrix converters in electric drives.


Prof. Dr. M. Liserre

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