SiC-Enabled Medium Voltage Isolated DC-DC Converter Based Power Optimizer for Large Photovoltaic Parks

DC architecture with an MVDC collection network is advantageous for Photovoltaic (PV) farms in reducing the capital by almost 25% and increase the revenue. Resonant converter is one of the most suitable topologies to realize the low voltage to medium voltage DC-DC conversion. This thesis deals with the design of a Medium voltage isolated LLC resonant converter. The converter is going to be first one of its kind by using medium voltage (10 kV) SiC devices on the medium voltage side of the converter. SiC devices enable very high frequency operation of the converter which leads to reduction in component size thus increasing power density. The design of resonant tank and the transformer is vital in improving the converter efficiency. Existing optimization techniques of resonant converters address either efficiency or power density of the converter as their objectives significantly influenced by intuition and unjustified parametric choices. To optimize the converter design achieving maximum efficiency at a significantly reduced volume, a multi-objective design optimization algorithm is being developed as a part of the thesis. A prototype for 1100V – 7000V, 25kW LLC resonant converter was also built which will be explained in detailed in coming chapters.