A Model for Field Aligned Starting

Field aligned starting (FAS) is a novel technique for starting 3-phase cage induction motors on a single-phase supply lines with minimal inrush currents. It uses a simple energy storage system that is independent of the mains supply to create two spatially displaced magnetic fields so that a high starting torque can be generated as the magnetic fields seek alignment. The started motor can then be mains connected to operate in a standard Steinmetz connection without incurring high inrush currents if the transition to the mains connection is properly timed. This paper describes the special features, theoretical concepts and advantages of the field aligned starting system, and presents a transient model through which the transient behavior of a 3-phase induction motor operated with field aligned starting can be analyzed. Detailed simulated and experimental results are presented in part II of this paper.