Single DC Source Based Asymmetric Multilevel Inverter : Principle, Modulation And Control

A single DC source-based asymmetric multilevel inverter is presented in this paper. The auxiliary dc sources of the proposed converter are replaced by floating capacitors using Level Doubling Network (LDN) principle. These capacitors do not require closed-loop control and naturally converge to the desired voltage in steady-state operation. The highest voltage bridge is supplied by the DC source, and all three bridges maintain a binary ratio of asymmetry. A combination of half-bridge and full-bridge LDNs are used to reduce the switch count with some reasonable trade-off in output voltage levels. Half-bridge LDNs are merged together to reduce the capacitor requirement further. Concept of the natural convergence of capacitor voltages and modulation technique is explained in details. Simulations of the proposed converter is carried out using MATLAB/SIMULINK. Simulation results matched well with theoretical analysis.