Cascaded H-Bridge Multilevel Inverter with Single DC Source for Medium-Voltage Drive Applications

A cascaded H- bridge multilevel inverter is presented in this paper. The inverter uses only one H-bridge that is excited from an isolated DC source and will be connected in cascade with a number of H-bridges whose dc links are formed by floating capacitors. Floating capacitors work on the principle of level doubling and have the capability to converge to the desired steadystate voltages without demanding any closed loop control techniques. In steady-state, all the DC link voltages maintain a binary asymmetric ratio. The inverter generates a seventeen-level phase voltage and a thirty-three-level line voltage at unity modulation index. Regardless of the modulation index and power factor, self-balancing of capacitor voltage is achieved. Simulation of the proposed converter is carried out in MATLAB/ SIMULINK.