Estimation of three-phase induction motor parameters

Abstract

Determination of a three-phase induction motor's characteristics from its equivalent circuit is very common and widely used. Computation of equivalent circuit parameters from test data is expensive. Alternative methods reported for parameter estimation, which do not require test data, give the parameter values of the approximate equivalent circuit of an induction motor. Characteristics obtained from the approximate equivalent circuit are, in general, not accurate enough for practical applications. This paper proposes a new method of estimating parameter values of the exact equivalent circuit of a three-phase induction motor. The method requires the name plate data, ratio of starting to full load torque and the efficiency and power factor values at half and full load. The proposed method was tested on several motors. The results/characteristics obtained by using the parameter values found by the proposed method and by Natarajan-Misra's method were compared and also checked with some of the actual values supplied by the manufacturer.