Simultaneous Control of Velocity and Field Flux of DC Nonlinear Motors

Abstract

This paper presents a novel strategy that exploits the properties presented by the nonlinear model of direct current motors, to obtain simultaneously the required control voltages in the armature and in the field windings when velocity and magnetic flux are considered as reference inputs. In this scheme, it is considered that the current signals for both windings are available, as well as the signal of the angular position. So by means of a second order filter, the signal that takes the place of the angular velocity is obtained. By using the Lyapunov stability theory, stability of the closed loop system, global convergence of angular velocity and field flux is concluded, moreover all the states variables are bounded for all initial conditions. Experimental tests confirm the theoretical proposal; that is, global asymptotic tracking of the angular velocity and field flux is ensured. The equations of this proposal are physically implementable and due to the structure of the control scheme, the voltages of both windings can be tuned in such a way that less current dissipates, resulting in energy saving and having the same response of velocity.