Rotor eccentricity fault compensation by voltage control of brushless DC motor

Rotor eccentricity is one of the common failures that can happen to a motor. In recent years, considerable amount of researches for rotor eccentricity fault diagnosis have been presented. However, no attention is given to the case of `eccentricity fault tolerant control´. The necessity of `eccentricity fault tolerant control´ is the importance of motor continuous operation during fault in sensitive industries with the best possible performance. Applying conventional control methods during eccentricity fault is not efficient. Since, these methods do not consider eccentricity fault effects such as distortion in flux linkage distribution and motor back-electro-motive force (EMF) waveform, as well as phase inductances changes which may lead to undesirable torque ripples. Hence, a new control strategy for improving motor performance is advantageous. In this study, a control method for brushless direct current (BLDC) motor in presence of static rotor eccentricity is proposed. On-line estimation of phase inductances and phase-to-phase flux linkages during eccentricity is the basis of the proposed control method. In the proposed strategy, the controller adjusts motor terminal voltages considering changes in motor specifications because of eccentricity, without using phase current control loop. Experimental results verify performance of the proposed method in reducing electromagnetic torque pulsations during fault.