Stability analysis of the Natural Field Orientation controlled induction machine drive

Natural Field Orientation (NFO) Control proposed in the 1980psilas is an alternative low cost control method for induction machines. The NFO Control has shown to have some stability issues in regeneration which have been partially addressed in the previous papers. In the present paper a linearised stability analysis is presented for the motor/drive system based on both the non-augmented and the augmented versions of the NFO control. Based on the results of this analysis, the limitations of the augmentation strategy are explored and conditions are identified when it does not ensure stability. Theoretical results are confirmed by simulations and experiments. Directions of further improvement of the NFO stability are outlined.