Application of an additional excitation in inverter-fed induction motors for air-gap eccentricity diagnosis
ABSTRACT 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.
Article: Fault detection by means of Hilbert-Huang transform of the stator current in a PMSM with demagnetization[show abstract] [hide abstract]
ABSTRACT: This paper presents a novel method to diagnose demagnetization in permanent-magnet synchronousmotor (PMSM). Simulations have been performed by 2-D finite-element analysis in order to determine the current spectrum and the magnetic flux distribution due to this failure. The diagnostic just based on motor current signature analysis can be confused by eccentricity failure because the harmonic content is the same. Moreover, it can only be applied under stationary conditions. In order to overcome these drawbacks, a novel method is used based upon the Hilbert–Huang transform. It represents time-dependent series in a 2-D time–frequency domain by extracting instantaneous frequency components through an empirical-mode decomposition process. This tool is applied by running the motor under nonstationary conditions of velocity. The experimental results show the reliability and feasibility of the methodology in order to diagnose the demagnetization of a PMSM. Peer Reviewed Postprint (published version)