Four Switch Buck-Boost Converter for Photovoltaic DC-DC power applications

Photovoltaic energy is a wide kind of green energy. A high performance on these systems is needed to make the most of energy produced by solar cells. Also, there must be a constant adaptation due to the continuous variation of power production. Control techniques for Power Converters like the MPPT algorithm (Maximum Power Point Tracking) present very good results on photovoltaic chains. Nevertheless, losses on power elements reduce global performance and the voltage/current adaptation is not always possible. In this paper, the use of the high efficiency structure Four Switch Buck-Boost for Photovoltaic systems is addressed. FSBB Converters present some advantages regarding other Power Converter structures: it has few electrical components, output voltage can be higher or lower than input voltage, and it presents a non-inverted output voltage as happens with others Buck-Boost Converters. A prototype of FSBB has been developed in order to exploit these new capabilities for a Photovoltaic DC-DC power application (solar module: 0V to 20V input voltage and different resistive loads). The implemented MPPT digital control chooses between a Buck or Boost mode, depending on the working conditions. Firstly, an introduction and the FSBB operating mode are addressed. Then, the adaptive MPPT control algorithm is detailed. And finally, the experimental results and conclusion are presented.