Conduction Modes of a Peak Limiting Current Mode Controlled Buck Converter

In this paper, analysis of a buck converter operated
applying a peak limiting current mode control is performed,
focusing regions where the limit cycle is unstable. Normalized
discrete time converter model is derived. Chart of operating
modes is presented, and it is shown that the converter exhibits
an infinite number of discontinuous conduction modes in an
area where the continuous conduction mode would be expected
assuming stable limit cycle. The converter is analyzed applying
numerical techniques to determine period number of different
discontinuous conduction modes and dependence of the output
current on the output voltage and the limiting current. The
numerical results agree with the analytical results in areas where
the limit cycle is stable, and differ in regions where the limit
cycle is unstable. Two different notions of stability, the limit cycle
stability and the converter open loop stability, are clarified.