Rotor parameter determination of three phase induction motors from a run up to speed test

This paper discusses developments in the implementation of a rapid online parameter determination method for three-phase induction motors without the need to connect a mechanical load or drive to the machine's output shaft. 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 to speed 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, main flux path saturation, leakage variation or flux migration due to rotor skew. Moreover the system can be used for the condition monitoring of any electrical drive system and can be permanently or temporarily connected to such a system for diagnosis.