A Novel Composite Cascade Multilevel Converter

Cascade inverter have become increasingly popular in recent years due to their practicability. This paper will present a novel composite cascade multilevel converter that is derived from these two topologies. The proposed converter structure is the series-connection of a five level diode-clamp converter and several three level H-bridge converters with equal dc bus voltage. Accordingly, for the novel inverter a hybrid modulation method which incorporates square-wave synthesis in conjunction with unipolar triangle carried-based PWM method is employed. With the novel topology consisting of a same DC bus voltage but different structure modules, the realization of a multilevel converter using a hybrid approach that involves higher voltage devices and fast switch devices operating in synergism is possible. Analysis of output spectral and the active power flow problem is carried out. The feasibility and the advantage are validated by simulation with MATLAB and the experiment.