Optimal efficiency operation of non-isolated DC/DC converter for high voltage ratio applications

In this paper, a global optimal study of the efficiency of a cascaded structure with synchronous rectification composed of two sub-converters has been presented, this converter allows obtaining high voltage ratio and consists of two-interleaved boost converter which was chosen as 1^st sub-converter and three-level boost converter which was chosen as 2^nd sub-converter. An optimal efficiency operation as a function of the intermediate voltage and the branch number of the first converter is studied by the aid of an adaptive losses estimation algorithm to estimate the components losses for each DC/DC converter. The estimated power losses of the two converters are modeled by two estimated resistances. These estimated resistances are used to study and optimize the relation between the intermediate voltage and the global efficiency and also the influence of the number of branches of the interleaved converter on the total global losses. The algorithm is theoretically analyzed, developed and compared with the experimental results. Experimental results allow validating the proposed analysis for maximizing global efficiency.