Application of an additional excitation in inverter-fed induction motors for air-gap eccentricity diagnosis

The application of an additional excitation in induction motor drives for static, dynamic and mixed eccentricity diagnosis is proposed. The additional excitation consists of a predetermined inverter-switching pattern applied while the fundamental excitation is cancelled. This excitation has been previously used to implement a position estimation strategy. This strategy obtains information about the rotor position from the machine saliencies effects over the zero sequence voltage. The air-gap eccentricity is a saliency that depends on the rotor position. For such reason, it also produces changes over the zero sequence voltage. In order to evaluate the feasibility of this proposal, a multiple coupled circuit model of the induction motor is used. Experimental results that validate the proposal are also presented.