Chattering Suppression of Sliding Mode Observer in Load Torque Estimation

Load torque identification is one of the most important factors in making a high-performance motor drive system. The paper proposes an enhanced sliding mode observer for the load torque estimation. To suppress the chattering, which is a significant issue in the sliding mode observer, this paper utilizes a feedforward compensation of the state variable. The error of the rotor position and the rotor speed is utilized in DCCSMO and SCCSMO respectively to make the feedforward compensation. With the modified structure of the sliding mode observer, the ripple of the estimation is effectively suppressed without any phase delay. The proposed method only requires the position sensor, and the implementation is easy. Also, the method does not require high computational cost. The improved performance of the proposed method is verified by various experimental results. The results show that the proposed method reduces the chattering up to 85% and achieves strong antidisturbance ability in comparison with the conventional method.