Nonlinear adaptive backstepping control of permanent magnet synchronous motor

This paper addresses the speed tracking problem of a permanent magnet synchronous motor (PMSM) under the influence of parametric uncertainties and external load torque disturbances. The nonlinear dynamics associated with both PMSM and load is considered time variant and uncertain. Two robust controllers, namely, backstepping and adaptive backstepping are designed to drive the speed of a PMSM to a predefined trajectory. The backstepping controller is used to stabilize and control the speed of motor while the uncertain parameters and disturbances are estimated by adaptive laws. These adaptation laws and the use of performance improvement term in the backstepping control reduce the gain requirements. The stability analysis of both the controllers via Lyapunov method ensures the asymptotic convergence of the overall close loop system. Theoretical analysis is presented to summarize characteristics of both the controllers. Numerical simulations are provided to verify effectiveness of the proposed controller.