Eccentricity Detection Of A Six-Phase Induction Motor With Hfi

Eccentricity detection is an important topic in motor fault diagnosis and bearingless motor controls. In this study, a novel method is proposed for eccentricity detection of a six-phase motor based on high-frequency injection (HFI). Unlike the other planes of the multiphase motors, the 0_ component (the average of the differences between adjacent phases) is seldom adopted for signal injections. The proposed method exploits the 0_ component for signal injection which allows the injected signals to be decoupled from the rotating-magnetic-field-producing planes without occupying any of them (so that they can be assigned to other uses). In this study, the induction motor under HFI is simplified as a model with mutually decoupled winding pairs. The HF impedance of each phase under eccentricity is derived on the basis of this model. The proposed method is drawn from these theories and verified with experiments. It is shown in the experiments that the proposed method has excellent linearity; the estimations on orthogonal directions are decoupled; and the proposed method has satisfactory tracking bandwidth. The influence of saturation on the proposed method is justified by simulations. The capability of the proposed method to discriminate between different types of eccentricities is proved with experimental data.