Control of velocity of DC motors by classical and passivity methods measuring only position: Theory and experimental comparison

Abstract

It is usual that in the design and development of control schemes, specifically in electrical machines, it is considered that the angular velocity measurement signal is available, but in practice, it is the signal of the angular position which is actually available. So that, in order to obtain the velocity, some numerical differentiation methods, whose dynamics is not included in the design of the controllers nor in the stability analysis of the closed loop, are implemented. In the present work, two control schemes for direct current motors are designed and implemented experimentally considering that only the angular position is measured. A filter of second order of relative degree 1 is used in order to obtain a signal for velocity feedback. The first one is a PID regulator of two degrees of freedom with an antiwindup structure, which is tuned analytically, and the second one is a new velocity tracking passivity based controller whose design takes advantage of the properties presented by the model of DC motor. Formal stability analyses for both control schemes are presented.