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 steady-state 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.