Rapid parameter determination for induction motor analysis and control

This paper describes the implementation of a rapid online parameter determination method for three-phase induction motors. The technique is based on data sampling during a normal run-up-to-speed test. The method has been refined such that even the normal locked-rotor and synchronous speed data are measured during the run-up test. Furthermore the technique takes into account rotor parameter variations with frequency due to skin effect (mainly due to double-cage or deep-bar rotor), and other nonlinear imperfections such as heating and main flux path saturation. Moreover, the monitoring system, capable of identifying three-phase RMS voltage and current, power, power factor, and speed within one or two sampling periods of less than a few hundred microseconds each, can be used for condition monitoring of any three-phase electrical drive system and can be permanently or temporarily connected to such a system for diagnosis.