Ordnarius (Professor), Institute for Electrical Drive Systems and Power Electronics, Department of Electrical Engineering and Information Technology, Technical University of Munich, GERMANY

Research interests:
encoderless control of electrical drives, modern control strategies for electrical drives, hardware-in-the-loop systems, renewable energy systems (focus on photovoltaics, wind energy & efficiency)

Keynote address:
Encoders for Simultaneous Sensing of Position and Speed - a Bottleneck in Electrical Drives with Digital Control

Speed and position encoders are essential components in electrical drives. High resolution encoders are necessary to obtain acceptable speed control behaviour. Therefore optical encoders are mainly used in servo drives as position (and speed) feedback. Optical encoders, however, do not provide a robustness comparable to electrical motors - hard environmental influences like mechanical shock and/or vibrations often damage the optical disc inside the encoder. Using resolvers provides better mechanical robustness - their resolution, however, is not sufficient for good speed control behaviour. Speed and position sensing in servo drives is an issue that is still not completely understood. Expressions like accuracy and resolution still get mixed up when engineers talk about encoders. These words, however, do describe different characteristics and should not be confused. The introduction of digital control has made this issue much more important for servo drive applications than before. The lecture is going to present some general explanations of speed and motion sensing as well as different encoder technologies available today and their characteristics, particularly with respect to digitally controlled servo drives. A message surprising most engineers is, that neither high resolution resolvers nor high resolution optical encoders do really provide features that could make them competitive to analogue precision tacho generators. As a result the behaviour of digital speed control can still not be as good as of former analogue speed control. The question why servo drives with digital speed control in fact are successful - nobody does really worry about any impact of optical encoders, because the performance of servo drives with digital control has indeed improved in comparison to former drives with analogue control - will be responded in the lecture as well. The technical reasons for that will be explained and hereby the lecture contributes to better understanding of speed and position encoders, which still are the technical bottle neck for further improvements in digital drive control.

Ralph KENNEL was born in 1955 at Kaiserslautern (Germany). In 1979 he got his diploma degree and in 1984 his Dr.-Ing. (Ph.D.) degree from the University of Kaiserslautern. From 1983 to 1999 he worked on several positions with Robert BOSCH GmbH (Germany). Until 1997 he was responsible for the development of servo drives. Dr. Kennel was one of the main supporters of VECON and SERCOS interface, two multi-company development projects for a microcontroller and a digital interface especially dedicated to servo drives. Furthermore he took actively part in the definition and release of new standards with respect to CE marking for servo drives. Between 1997 and 1999 Dr. Kennel was responsible for "Advanced and Product Development of Fractional Horsepower Motors" in automotive applications. His main activity was preparing the introduction of brushless drive concepts to the automotive market. From 1994 to 1999 Dr. Kennel was appointed Visiting Professor at the University of Newcastle-upon-Tyne (England, UK). From 1999 - 2008 he was Professor for Electrical Machines and Drives at Wuppertal University (Germany). Since 2008 he is Professor for Electrical Drive systems and Power Electronics at Technische Universitaet Muenchen (Germany). His main interests today are: Sensorless control of AC drives, predictive control of power electronics and Hardware-in-the-Loop systems. Dr. Kennel is a Senior Member of IEEE, a Fellow of IET (former IEE) and a Chartered Engineer in the UK. Within IEEE he is Treasurer of the Germany Section as well as Distinguished Lecturer of the Power Electronics Society (IEEE-PELS). Dr. Kennel has received in 2013 the Harry Owen Distinguished Service Award from IEEE-PELS as well as the EPE Association Distinguished Service Award in 2015. Dr. Kennel was appointed "Extraordinary Professor" by the University of Stellenbosch (South Africa) from 2016 to 2019 and as "Visiting Professor" at the Haixi Institute by the Chinese Academy of Sciences from 2016 to 2021. There he was appointed as "Jiaxi Lu Overseas Guest Professor" in 2017.

DAS 2018
Keynote Speaker

Senior Member IEEE


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