A Three-Phase, Nine-Level, Switched-Capacitor-Based H-Bridge Multilevel Inverter Topology

Abstract

This work presents a three phase, nine level, switched-capacitor based H-bridged multilevel inverter topology. The presented inverter configuration is capable of synthesizing five output voltage levels with a single isolated DC voltage source per phase. The power circuit configuration is a modification of the conventional H-bridge inverter by the addition of an auxiliary circuit. This auxiliary circuit consists of two active power switches, a diode and a capacitor. Proper control of the consisting elements in the auxiliary circuit generates existing input voltage across the capacitor bank; so that two isolated voltage sources are impressed across the H-Bridge. The resultant effect of this is the synthesis of multilevel output voltage waveform whose peak value doubles that of the single DC source per phase. The multiple carrier, in-phase disposition, pulse width modulation scheme is used to generate the gating signals for the power switches. The validity of the system is verified through MATLAB/SIMULINK simulations and experimental results. The three phase design presented herein is rated 2kW, with an input DC voltage of 100V and peak phase and line voltage values of 200V and 400V respectively