A robust adaptive precision position control of PMSM

A new control method for precision robust position control of a permanent magnet synchronous motor (PMSM) is presented. In direct drive motor systems, a load torque disturbances directly affects the motor shaft. The application of the load torque observer using a fixed gain to solve this problem was published by J.S. Ko et al. (see IEEE Trans. Ind. Electron., vol.40, no.5, p.512-20, 1993). However, the motor flux linkage cannot be determined precisely for a load torque observer. Therefore, an asymptotically stable adaptive observer based on a deadbeat observer is considered to overcome the problems of unknown parameters, torque disturbance and a small chattering effect. To find the critical parameters the system stability analysis is carried out using the Lyapunov stability theorem.