A novel hybrid speed estimator of flux observer for induction motor drives

This paper proposes a novel hybrid speed estimator that gives the synergetic effect between the model based and the saliency based field orientation for induction motor drives. The model based field orientation consists of a flux observer with an adaptive speed estimator that has unstable regions at zero frequency and zero speed. Saliency based flux orientation utilizes magnetic saliencies caused by saturation and high frequency injection that causes the torque ripples due to chattering. The chattering occurs by the higher cut-off frequency of flux angle estimation to keep the high dynamics. The proposed method compensates both faults and realizes complete speed estimation from zero to high-speed condition including zero stator frequency.