Modularized Partial Power Processing DC–DC Converters

The partial power processing (PPP) technique for power converters is widely used in renewable energy, electric vehicles, and dc microgrids due to its high power density and efficiency. Conventional PPP topologies are typically designed for either photovoltaic strings or two dc ports, with this research expanding the latter. The existing PPP two-port scheme connects one dc–dc converter port in series between the source and load, allowing only partial power to be processed while the rest is delivered directly, reducing converter size and power losses. However, existing two-port PPP schemes are limited in handling complex, multiport, or buck-boost applications.
This thesis extends the basic PPP two-port design by introducing modular PPP topologies. It splits the isolated dc–dc converter into two modules: one series-connected between the source and load, and the other parallel to either the source or load. The series and parallel modules handle partial power caused by voltage and current difference between the source and load. A general derivation principle is proposed for PPP multiport structures, requiring at least one series-connected module for each pair of dc ports and one parallel-connected module for all the dc ports, ensuring voltage and current balance. Based on this principle, nine PPP three-port dc–dc structures are derived, with a methodology for selecting the appropriate topology for specific applications.
The thesis also presents a PPP single-input/output N-outputs/inputs dc–dc converter with N+1 radial connection modules. A single-input dual-output converter with active bridge modules is constructed and measured. Additionally, a novel T-shaped PPP buck-boost dc–dc converter is proposed, featuring a central parallel module for intermediate voltage regulation and two series modules with opposite polarities for buck-boost operation. This design allows for buck-boost operation within a narrow voltage gain range without polarity reversal. Experiments validate the theoretical analysis of both the three-port and buck-boost converters.