Power loss analysis of a single-switch non-isolated DC/DC converter

A power loss model of a single-switch non-isolated dc/dc converter is developed in this paper. The converter is formed by combining a buck converter with a buck-boost converter. It can be used in a stand-alone photovoltaic (PV)-battery powered pump system. With only a single transistor, the converter is able to efficiently perform three tasks simultaneously, namely, maximum power point tracking (MPPT), battery charging and driving the pump at constant flow rate. The conduction and switching losses of each individual components of the converter and the inductor core loss are calculated and analyzed when the two inductors operate in different modes. The analysis shows that the output stage inductor and power diode are the major contributors to the total power loss. A 14W laboratory prototype converter is built and the experimental results are compared with the model analysis.