A Highly Reliable and Efficient Differential Type Buck-Boost DC-AC Converter

The conventional structure of buck-boost inverter uses IGBTs. IGBTs have features like long tail current, fixed voltage drop and that is why its switching losses are high. In this paper switching cells structured buck-boost inverter is proposed. In switching cell structure, MOSFETs and external diodes with very fast reverse recovery characteristics are used, while the body diodes have no chance of conducting current. As a result, switching and conduction losses are reduced and diode performance is improved. It has an additional advantage of having no shoot-through problem which increases its reliability. In order to further increase the efficiency, a modified switching scheme is also proposed. In the proposed switching scheme power MOSFETs of each individual buck-boost converter operate in high frequency for only half cycle. Due to which switching and conduction losses are greatly reduced resulting in further improving the efficiency.