Calculation of load-dependent equivalent circuit parameters of squirrel cage induction motors using time-harmonic FEM

摘要

Purpose - The purpose of this paper is to define a time-efficient numerical procedure for the extractionrnof load-dependent equivalent circuit (EC) parameters of induction machines. The parameters arerndetermined for every operating point, thus their variation due to skin effect and material saturationrnunder arbitrary load condition is taken into consideration.rnDesign/methodology/approach - Two methods are presented and compared. The first one isrnbased on the numerical simulation of the standard measurement process, yielding an EC with constantrnparameters. A time-harmonic finite element analysis is applied in the second method to calculate thernload-dependent EC parameters. Material linearization and the superposition principle for the magneticrnflux are employed to define the leakage inductances.rnFindings - A distinct load dependence of all EC parameters has been proven as well as the clearrndisparity between stator and rotor leakage inductances. These effects can only be taken accurately intornaccount by the EC obtained by the second numerical procedure proposed.rnOriginality/value - The presented method successfully overcomes typical problems of thernmeasurement process and of the standard numerical procedure for EC parameter estimation, thus thernobtained EC parameters are load-dependent while the physical interpretation of the variables andrnparameters remains straightforward. Hence, the paper of the internal machine variables is enabled.