R. Wieser:
"Modellierung umrichtergespeister Asynchronmaschinen zur Berechnung des Drehmomentes";
Supervisor, Reviewer: H. Kleinrath; E372, 1996.

The dissertation thesis presents models of inverter-fed induction machines, which are capable of calculating torque during transient operating conditions. The models are especially adjusted to the dynamic features of field oriented controlled machines and the measurement technique considers the distorted current- and voltage wave forms of voltage source inverter fed machines. The integration of loss mechanisms into the on-line calculation of the flux space phasors of the machine leads to a most accurate computation of the machine states. The variable parameters of the machine are corrected by an on-line parameter adaptation during operation.
Torque calculation is based on of two different independent machine models. The first model (current model) computes air gap torque without dynamic limitations. It is corrected by a second slower and parameter insensitive voltage model. A novel combination of analog-to-digital conversion with an inherent stable voltage model structure makes precise and reliable stator and rotor flux computation possible. Eddy currents, hysteresis effects in the iron as well as load depended changes in the flux path are taken into account.
Shaft torque is calculated from air gap torque and acceleration torque. The latter is derived from the signals of an optical encoder by a Kalman filter. Experimental results on test stand drives demonstrate the accuracy and the excellent dynamic behavior of the torque calculator during load steps and at stand still.