M. Eder:
"Anwendung des INFORM-Verfahrens zur geberlosen Feldorientierung der Asynchronmaschine eines Traktionsantriebes bei Flußstillstand und kleinen Drehzahlen";
Supervisor, Reviewer: H. Kleinrath; E372, 1997.

The doctoral thesis introduces an application of the "INFORM" method (Indirect Flux detection by On line Reactance Measurement) which allows the field oriented control of induction machines both at low speed and standstill. Operating without mechanical sensors (tachometers, position encoders) this method yields cheaper and more robust drive solutions. The basic idea is to utilise the local influence of the main flux saturation on leakage induction by real time reactance measurement. INFORM-based data about the flux axis (flux angle) are directly used for field orientation. A simple INFORM modell of the induction machine at no load demonstrates the fundamental concept and operating mode. The practical detection of the flux axis is disturbed by systematic interference effects like EMF and stator resistance. In order to eliminate these effects appropriate measurements and mathematical evaluations have been developed. The static and dynamic reaction of the INFORM based field oriented control having been explored on a test stand and the INFORM algorithm having been optimised, the method has been applied in practice as a part of a traction drive control for an electrical vehicle (VW-Transporter T4). The practicability of the proposed method with reference to electrical traction has been verified in a 22,000 km test in Vienna trafic.