New MRAC load torque observer for the position control of BLDCmotor

摘要

A new control method for the robust position control of abrushless DC (BLDC) motor using an asymptotically stable adaptive loadtorque observer is presented. A precision position control is obtainedfor the BLDC motor system, approximately linearized, using thefield-orientation method. An application of the load torque observerusing a fixed gain has been published by Jong Sun Ko et al. (1993).However, the flux linkage is not exactly known for a load torqueobserver. Therefore, a model reference adaptive observer is consideredto overcome the problem of the unknown parameter in this paper. Astability analysis is carried out using the Lyapunov stability theorem.As a result, an asymptotically stable observer gain can be obtainedwithout affecting the overall system response. The load disturbancedetected by the asymptotically stable adaptive observer is compensatedby feedforwarding the equivalent current having the fast response