Analysis of one cycle controlled SEPIC converters

This paper demonstrates that one cycle control (OCC) technique cannot be used in conjunction with continuous conduction mode (CCM) operated Sepic converters, as it inherently leads to unstable operation. The approach adopted by the authors to prove this is similar to that used to investigate current-mode controlled converters, except for the fact that the perturbation is referred to the capacitive voltage applied across the diode when off. It is demonstrated that in CCM this perturbation is amplified from one switching cycle to another and thus it results in instability. The theoretical results are verified through computer simulation using the Caspoc package.