Estimation of parameters of induction machines from no-load starting without speed acquisition
The paper addresses the problem of practical estimation of the parameters of induction machines without speed measurement and using only no-load transient voltages and currents, acquired during a startup test performed at the final stage of the production line at the manufacturer site. The test aims to enable a first estimate of the machine parameters, from which standard performance requirements — such as starting torque, maximal torque, rated power factor and efficiency — can be checked using known models. A method is proposed to estimate the speed and electromagnetic torque alone from stator voltages and currents and also from measured stator resistance (Rs). Based on the estimated speed and torque, electrical and mechanical parameters are then estimated by the Classical Minimal Squares Method. To validate the method, simulation data are used, to which error to the stator resistance and noise to the currents and voltages are added. The results show that the proposed method is able to estimate the parameters with acceptable errors even with variations of ±20% in Rs and under different noise levels.