A New Control Law of Boost and Buck-Boost DC-DC Converters.

Abstract

It is well known that the state-space averaging models of the boost and the buck-boost converters are bilinear systems. The stability and output regulation problems of bilinear systems are so complicated that most previous works which deal with the above two types of converter in the state space are confined to the analysis of linear approximated systems (small signal models). However, any control law for small signal model does not generally guarantee the global stability, but the partial stability of the system.A new control law based on the bilinear large signal model is proposed for achieving output regulation of the boost and the buck-boost converters. The control law is derived from directly applying the Lyapunov stability theory to the bilinear large signal model. The acutual realization of this control law might have some difficulties, because it is given as a solution of differential equations with respect to the state and input variables. However the closed loop system with this control law is expected to possess the robust stability achieving an excellent output regulation for large changes of reference, load and source voltage from the theoretical point of view. Some desirable features of the new control law are demonstrated by the numerical simulation.