Weak signal extraction of micro-motor rotor unbalance based on all-phase fast Fourier transform

To improve the dynamic balancing accuracy of the micro-motor rotor, an unbalanced vibration feature extraction based on an all-phase fast Fourier transform (APFFT) method is proposed. The amplitude and phase of the signal are extracted by spectrum analysis after windowing the unbalanced signal. The mathematical model is derived to simulate the weak signal of rotor unbalance. The simulation results show that this method is accurate in extracting the weak signal of the rotor under different noise levels. The micro-motor rotor unbalanced test system is developed for experimental validations. The accuracy and stability of the vibration amplitude and phase extracted by the APFFT are better than the accuracy and stability from the hardware filtering method. The rotor unbalance is reduced by more than 80%. Furthermore, secondary balance of the rotor after the first balance is carried out. The proposed method can still extract the residual unbalance of the rotor. The results demonstrated that the proposed method can achieve a reduction rate of 90% and the accuracy is within 5 mg, verifying the effectiveness of the proposed method for high-precision rotor dynamic balance.