Analysis of Design Requirements and Optimization Possibilities of Partial Power Converter for Photovoltaic String Applications in DC Microgrids

The paper analyzes the application flexibility of partial power converters for interfacing photovoltaic strings in dc microgrids. Step-up/down partial power converters were considered for providing the lowest active power processing. This study considers three Si-based photovoltaic modules commonly used in residential applications: 54-, 60-, and 66-cell. Different configurations of photovoltaic strings are analyzed to find at what voltages most energy is generated in hot and cold climates. Combining these results with the operating voltage range of a droop-controlled dc microgrid yields design requirements for the partial power interface converters. The proposed design limits the maximum power the converter processes to optimize its components. Next, the application of the topology morphing control is studied regarding the performance enhancement of partial power converters. Experimental results verify good converter performance and feasibility of efficiency improvement with the topology morphing control.