Parameter Estimation of Field Aligned Starting

Field aligned starting (FAS) is a technique that starts single-phase Steinmetz operated 3-phase cage induction motors with minimal inrush currents through the generation of a very high impulsive starting torque. The high starting torque is achieved at the expense of imposing higher than rated voltages, currents and frequencies upon the motor windings, which invariably cause motor parameters to deviate dynamically from their steady state values. Transient analysis of FAS is thus possible only with an accurate estimate of dynamically varying motor parameters. This paper presents a simple yet effective parameter estimation method that has been specifically derived to suit the unusual starting conditions imposed on the motor by FAS. The proposed method is validated by simulated and experimental results of a 3 kW motor, started under various starting conditions with FAS. A discussion of the impact of the variations of the motor parameters on the experimental results is also presented.