Analysis and characterization of a square-wave modulation method for single-phase cascaded h-bridge multilevel inverters

Abstract

Cascaded multilevel inverters offer several advantages over other multilevel structures: modularity, high voltage capability, reliability. Additionally, a large number of cascaded inverters using a square wave modulation method allow low losses in the inverter and low harmonic distortion in the output voltage. This paper analyzes the main features of one of these modulation methods especially in what concerns to real-time implementation in a FPGA, output voltage distortion in single-and three-phase systems and modulation range in static and dynamic conditions. Also, scalability is addressed in order to evaluate the method’s capability to be used in high voltage applications. Simulation results with a different number of H-bridge inverters are presented and they allow obtaining the main conclusions; experimental results verify and support those conclusions.