The paper describes a model-reference adaptive
system (MRAS) for the estimation of induction motor speed
from measured terminal voltages and currents. The estimated
speed is used as feedback in a vector control system, thus
achieving moderate bandwidth speed control without the use of
shaft-mounted transducers. This technique is less complex and
more stable than previous MRAS tacholess drives. It has been
implemented on a 30-hp laboratory drive, where its effectiveness
has been verified.