A Generalized Non-Carrier Modulation Technique for an Asymmetric Source Configuration of Single-Phase CHB-MLI Topology Using PLECS Tool

Abstract

For single phase Cascaded H-Bridge (CHB)-Multilevel Inverter (MLI) topology, a generalized modulation technique without carrier signals have been implemented in this paper. When considering symmetric source arrangement, the CHB architecture typically necessitates a greater number of cells/units and segregated DC sources to provide higher levels of output and increasing the cost need. An asymmetric source arrangement with fewer modules and segregated DC sources is described in the literature to produce greater level output. The CHB-topology delivers 27 and 19 levels of output with only three modules and three DC sources by considering trinary (1:3:9) and quasi-linear (1:2:6) source configurations. Most control approaches requires high switching frequency carrier signals and states to decoder arrangement in order to provide a specific level output. However, the proposed control technique does not require states to decoder and carrier signals then reducing control complexity and computational strain on the processor. This control approach also produces less Total Harmonic Distortion (THD) then the filtering requirements are minimal. It is well suitable for an asymmetric source configuration of CHB-MLI topology without aid of high switching frequency carrier signals. The PLECS platform is used to validate the operation and proposed control mechanism.