Symmetrical Flying Capacitor Based Multilevel Inverter with Reduced Voltage Stress for High Frequency Aircraft Application

Abstract

The modular flying capacitor multilevel inverters (FC-MLIs) features a competitive market for both medium and high power industrial applications. In order to generate a higher number of staircase waveforms, the conventional multilevel in-verters (MLIs) require more number of dc sources and passive components, which increase the loss and reduce the reliability. Thus, to elevate the above problem, this article proposes a new multilevel inverter topology with one flying capacitor (FC) and reduced DC sources. This circuit offers the advantage of double output voltage levels when compared to conventional MLI topologies. In all modes of operation, the conducting switches are equal, and also the blocking voltage across all the switches is the same. Thus, this FC-MLI yields nine-level output with help of eight unidirectional switches, two bidirectional switches, two symmetrical sources, and one FC with a voltage rating of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{in}/2$</tex> . The experimental results are validated on a laboratory prototype for pure resistive and inductive load. Peak efficiency of 94.8% is found for a 625 W prototype. An effective comparative assessment is presented with the existing state-of-art nine-level FC-MLI.