High-voltage DC (HVDC) transmission is a future trend in photovoltaic (PV) systems due to higher efficiency and lower control complexity. High-power high-voltage interface DC-DC converters are a major bottleneck of HVDC PV systems. Hence, there is a significant value to explore the topologies, control schemes, and reliability of the interface DC-DC converters.
Dual active bridge (DAB) DC-DC converter has wide application in PV systems, and compared with traditional two-level DAB converters, multilevel converters can burden higher rated voltage and realize higher step-up ratio, thus reduce the number of cascaded converters and cut the hardware cost. However, the research about multilevel DAB converters is still in the initial stage. The aim of this Ph.D. project is thus to explore the performances of multilevel DAB converters on the following aspects: (a) Basic characteristics including static and dynamic characteristics, such as dead-time effects and DC bias. (b) Efficient modulation schemes. (c) Bi-oriented design considering efficiency and reliability. (d) Modulation of cascaded DAB converters.
Collaborator: Shandong University.
Funding: China Scholarship Council (CSC).