DC motor speed control through AC/DC converter

We are considering the problem of DC motors through AC/DC power converters of the Buck-Boost type. The dynamics of the latter are explicitly accounted for in the controller design, unlike in most previous works. The control objectives are twofold: (i) speed regulation, (ii) unitary power factor operation. The control problem is dealt using the backstepping design technique. The regulator thus obtained involves two loops: (i) an inner loop enforcing the electric network voltage and current to be in phase (unitary power factor), (ii) an outer loop regulating the motor speed. This shown to achieve its objectives.