Position control of the permanent magnet synchronous motor based on backstepping method and load torque observer

A nonlinear position tracking controller is presented for a three phase permanent magnet synchronous motor (PMSM) when load torque is unknown. The controller is constructed recursively step by step based on the methodology of backstepping. In order to solve the problem of the overparametrization of load torque estimator of the adaptive backstepping technique, a load torque observer is applied to estimate unknown load torque and to regulate the control inputs. Theoretical analysis and simulation results clearly show that the proposed controller has good position tracking performance and is robust to uncertainties of external load torque. © 2013 ICIC International.