Invited Talk

Invited Talk 2 :

What Is Wrong In Most Papers With The Equivalent Circuit For LIMs

The difference between equivalent circuits of cage induction motors (rotor with concentrated parameters) and single-sided LIMs with solid steel or Al cap over solid steel (reaction rail with distributed parameters) has been analyzed. In LIMs, both the resistance and reactance of the secondary circuit are functions of the slip and the magnetic field intensity. This results from the definition of the wave impedance of a solid conductive medium, i.e., the ratio of the electric component–to–the magnetic component of field intensities at the surface. The impedance of the reaction rail must be derived on the basis of the electromagnetic field distribution. Most authors make typical errors assuming that the reaction rail of a LIM with distributed parameters behaves similar to the cage rotor of an induction motor. Therefore, in most papers the same T-type equivalent circuit as for cage induction motors is applied to LIMs with distributed-parameters reaction rail. Although, the derivation of equation for the longitudinal end effect is complex, the longitudinal end effect can be simply included in the T-type equivalent circuit by introducing the so called “end effect impedance” in the vertical branch. Both equivalent circuits without and with the end effect taken into account have been considered.



Jacek F. Gieras (IEEE Fellow, 2002) graduated in 1971 from the Technical University of Lodz, Poland, with distinction. He received his PhD degree in Electrical Engineering in 1975 and Dr habil. degree (corresponding to DSc), also in Electrical Engineering, in 1980. His research area is Electrical Machines, Drives, Electromagnetics, Railway Engineering and Aircraft Electric Systems.


From 1971 to 1998 he pursued his academic career at several Universities worldwide including Poland, Canada, Jordan and South Africa. He was also a Central Japan Railway Company Visiting Professor at the University of Tokyo (Endowed Chair in Transportation Systems Engineering), Guest Professor at Chungbuk National University, Cheongju, South Korea, Guest Professor at University of Rome La Sapienza, Italy, Guest Researcher at Korea Electrotechnology Research Institute, Changwon, South Korea, and Guest Professor at Zhejiang University, Hangzhou, China. Since 1998 he has been affiliated with United Technology Corporation, U.S.A., most recently with UTC Aerospace Systems Applied Research.


Prof. Gieras authored and co-authored 13 books, over 250 scientific and technical papers, 102 US patents, 17 European patents and 4 Polish patents. Two of his books, i.e., "Linear Induction Motors", Oxford University Press, 1994 and "Linear Synchronous Motors", CRC Press – Taylor & Francis, Boca Raton, Florida, 1999, second edition 2012, are devoted to linear motors and magnetic levitation.


He is a Fellow of IEEE, USA, UTC Aerospace Systems Fellow, USA, Full Member of International Academy of Electrotechnical Sciences, and member of Steering Committees of numerous international conferences.