Bearing fault diagnosis of BLDC motor using Vold-Kalman order tracking filter under variable speed condition

Order analysis (OA) is a very effective method for motor bearing fault diagnosis with variable speed. However, the traditional order analysis methods require the tachometers to obtain the speed information. This paper proposes a novel tacholess OA method for brushless direct current motor (BLDCM) bearing fault diagnosis under variable speed condition. The new method estimates rotating phase information accurately by using the Vold-Kalman order tracking filter which only requires the phase current and the vibration signals of the BLDCM. Hence, the proposed method can be realized without a tachometer. The extracted rotating phase is used to resample the vibration signal. The resampled signal is demodulated, and the envelope order spectrum is calculated for bearing fault identification. The effectiveness of the proposed method is verified by experiments.