High voltage gain minimum‐phase isolated DC‐DC converter with improved transformer utilization

Abstract

The standard structure of an isolated SEPIC (iSEPIC) does not have a minimum‐phase nature, which signifies no additional support for the output capacitor during ON‐time conditions. Consequently, it has high voltage stress, right half plane (RHP) zeros presence, DC component in the transformer core, and less transformer utilization. This paper presents a modification in a iSEPIC converter having higher voltage gain over a conventional iSEPIC converter. This work analyzes a modified iSEPIC structure by providing additional support to the output capacitor during ON‐time conditions. As a result, the nonminimum‐phase nature will be transformed into the minimum‐phase nature. Consequently, all the mentioned demerits of the standard iSEPIC structure are eliminated The derived discrete‐time modeling analyzes the RHP zeros dependence on the load variation. This modification also leads to improvement in dynamic performance to accommodate the load variation. Finally, a 60 W modified iSEPIC prototype is developed to validate the proposed analysis.