Estimation of Unbalance Mass for Sensorless Electric Drive System Based on Sliding Mode Observer and FFT

The unbalance mass may cause the decentration and vibration adversely affecting the working performance and service life of the rotating machinery equipped in sensorless electric drive systems, such as fans and drum washing machines. The unbalance mass is almost inevitable, and it’s difficult to estimate it due to the lack of corresponding sensors. This paper proposes an estimation scheme of unbalance mass for sensorless electric drive systems equipped with rotating machineries. A sliding mode observer is implemented to determine the rotor position and velocity information. The overall moment of inertia is computed by the fast Fourier transform method. The unbalance mass is estimated according to the dynamic model of motors and the values obtained above. Simulations and experimental validations demonstrate that the proposed estimation scheme can achieve accurate estimation of the unbalance mass in spite of variation of balanced loads.