Parameter Sensitivity Issues in Natural Field Orientation

Natural field orientation (NFO) control was first developed in the mid 1980s and is a simplified version of the stator flux oriented (SFO) control. NFO has some unique properties, including very high tolerance to the stator resistance errors. In this paper NFO´s sensitivity to this and other parameter errors is explored, and its parameter robustness is compared to the polar form of SFO. A simple augmentation to both algorithms is developed which improves their parameter error robustness. This paper also shows that this augmentation, previously suggested to improve the NFO control frame stability, also has a positive effect on SFO frame stability by eliminating undesirable oscillations near the synchronous frequency.