Multilevel converters: review, form, function and motivation

The paper is devoted to the outlines of converters and more in particular the form and function of multilevel converters. The first commutation principles are recalled towards the switch function today being implemented with solid state devices. Solid state devices combined in various topological combinations enables the connection of various sources and loads of different kinds. The primary energy source can be for instance a battery, solar panel, fuel cell, generator etc while the load can be anything from a motor to the connection with the power system. As will be shown with multilevel converters the number switch functions is increased, while increasing the power ratings with a switching frequency as close to the fundamental frequency. Multilevel converters provide and effective switching frequency increase allowing negligible filter requirements.