Robust Speed Control of Permanent Magnet Synchronous Motors Using Two-Degrees-of-Freedom Control

In this paper, a two-degrees-of-freedom controller is proposed for robust speed regulation in permanent magnet synchronous motors (PMSM). Our proposal constitutes an extension of a control scheme previously introduced in the literature for permanent magnet brushed dc motors to the case of PMSM. We formally prove global exponential stability of the desired equilibrium point, and we take into account the nonlinear motor electric dynamics during the stability proof. Several experiments are presented, which verify that the closed-loop control system is robust with respect to parameter uncertainties and outstanding torque disturbance rejection is performed. These results are compared to those obtained with a standard proportional-integral speed control scheme. We conclude that good performance, simplicity, and easy controller commissioning in practice are significant advantages of our proposal, which render it suitable for the motor drive community.