DYNAMIC PERFORMANCE LIMITATIONS FOR MRAS BASED SENSORLESS INDUCTION-MOTOR DRIVES .2. ONLINE PARAMETER TUNING AND DYNAMIC PERFORMANCE STUDIES

The paper investigates the dynamic performance limits of a sensorless cage induction motor drive utilising an MRAS based speed and flux esti mator operating within a direct rotor flux orientated (DRFO) vector co ntroller. A 4kW experimental sensorless drive rig has been tuning tech niques for the rotor time constant and stator resistance. These techni ques, together with their implementation and experimental performance, are described, The tuning of the rotor time constant allows for robus t speed estimate accuracies of 0.1. rev/min to be attained. The tuning of the stator resistance to near 1% allows for improved low speed per formance and enhanced speed loop dynamics. The resulting speed loop dy namics of the tuned sensorless drive is compared experimentally with a sensored vector control drive and the limiting factor for both is see n to be the quality of the speed feedback signal. A quantitative goodn ess factor for comparing the speed loop dynamics is introduced and the comparison discussed.