A New Method to Estimate Induction Machine Parameters from the No-Load Startup Transient

The paper proposes a new method to estimate the electrical parameters of three-phase induction machines based only on the voltages and currents of the stator acquired during a no-load startup test. The method is based on the instantaneous impedance and on the rotor speed, both estimated according to procedures detailed in the paper. Parameter variations with the speed are determined based on the concept of data windowing and using a single-cage model. Theoretical and practical considerations are presented and discussed, with the method being validated through simulations and also through experimental results obtained for eleven machines with power from 5.5 to 75 kW. The most relevant characteristic of the proposed method is that the variation of the resistance and leakage inductance of the rotor during the transient, caused mainly by skin effect, can be effectively and systematically assessed. The practical results proved that the method has great potential to advantageously replace traditional no-load and blocked-rotor tests as it requires less time and has much lower associated costs.