Adaptive disturbance observer design for servo drive system with time-varying load inertia

Considering the variations of load inertia in industrial applications, an adaptive disturbance observer (ADOB) for the permanent magnet synchronous motor (PMSM) servo system is proposed in this paper. Firstly, an inertia identification method is employed to obtain the system inertia online. Secondly, a modified disturbance observer is proposed based on the identified inertia to estimate the disturbance torque, and feed the disturbance compensation forward to the torque controller. Lastly, speed controller gains are tuned automatically according to the identified inertia. Simulation results show the validity of the proposed ADOB and have better performance than general DOB.