Sensorless speed operation of cage induction motor using zero drift feedback integration with MRAS observer

The paper investigates the improvement in sensorless vector control of induction machines through the use of a non-linear feedback integrator embedded in a standard rotor flux model reference adaptive system (MRAS)-based observer. The feedback integrator compensates for drift and dc-offset and is capable of open loop flux estimation down to frequencies below 0.1 Hz. The paper presents experimental results of sensorless speed controlled induction motor exploiting a MRAS observer. The sensorless system shows good performance down to frequencies of 0.2 Hz.