Transient Modeling of Squirrel-Cage Induction Machine Considering Air-Gap Flux Saturation Harmonics

A transient model of a squirrel-cage induction machine, including air-gap flux saturation harmonics, is presented in this paper. The machine model is based on a flux model, where the winding magnetizing fluxes are directly calculated from the resultant air-gap magnetomotive force, avoiding the use of complicated inductance harmonics. The effects of the fundamental and third harmonic components of the air-gap flux are incorporated in the model by two saturation factors. Moreover, the saturation effects are incorporated in the machine´s torque equation, allowing the model to investigate the machine´s performance under any load condition. The machine parameters, including saturation data, are obtained via the conventional no-load and locked-rotor tests, with access to the stator neutral connection. The proposed model is validated by experimental results for a squirrel-cage machine and can be used to predict machine transient states.