Analytic-wavelet-ridge-based detection of dynamic eccentricity in brushless direct current (BLDC) motors functioning under dynamic operating conditions

A new method using the analytic wavelet transform of the stator-current signal is proposed for detecting dynamic eccentricity in brushless direct current (BLDC) motors operating under rapidly varying speed and load conditions. As wavelets are inherently suited for nonstationary signal analysis, this method does not require the use of any windows, nor is it dependent on any assumption of local stationarity as in the case of the short-time Fourier transform. The proposed technique uses analytic wavelets, which are smooth wavelets that possess both magnitude and phase information. This makes them particularly suitable for motor-fault diagnostics. Experimental results are provided to show that the proposed method works over a wide speed range of motor operation and provides an effective and robust way of detecting rotor faults such as dynamic eccentricity in BLDC motors.