Controllability of nonisolated DC-DC converters with constant-power-load

This paper addresses the controllability of six types of nonisolated DC-DC converters (i.e. Buck, Boost, Buck-Boost, SEPIC, Cuk and Zeta) feeding the constant power load (CPL). The operation principle of SEPIC is presented so that the drift vectors and control functions are derived, which demonstrate that each switching mode is an affine nonlinear subsystem. Employing the recent findings on the controllability of switched nonlinear systems, we prove that every state on the maximal integral manifold is an interior of the convex cone generated by (G-shifted) drift vectors and control functions, thus the nonisolated DC-DC converters with CPLs are controllable. This technique could be applied to analyze other isolated converters.