A Review of Series-Connected Partial Power Converters for DC-DC Applications

This article presents a review of series-connected partial power converters (S-PPCs) for dc-dc applications, which allows carrying out the partial power processing (PPP), whose main goal is to achieve a reduction of the power processed by the converters. An analysis of the S-PPCs' characteristics, topologies, and applications concerning the active and nonactive power processing is presented. The power processing factor (PPF) is then defined, which refers to the active power and depends exclusively on the voltage regulation range. The so-called Fryze power factor (PF) is used to evaluate the nonactive power processed, which depends on the topology voltage and current waveforms. Due to the lack of research around step-up/-down S-PPCs, this article presents the restrictions and requirements for the design of this type of S-PPCs. Finally, it is demonstrated that the turns ratio of magnetic devices can be optimized to reduce the nonactive power and improve the converter Fryze PF, ensuring PPP. In order to validate the analyses, two 2200-W prototypes were built and evaluated for a photovoltaic (PV) application example. Experimental results show that the reduction of both the active and nonactive power processed by the S-PPCs results in lower component ratings and higher efficiencies.