Study of floating source dynamic behaviour in imbricated cell converter

Converters which have floating voltages in their topologies, made with capacitors. One aim of the capacitors is to divide voltages among switches. Then, each capacitor state of charge is crucial for the good running and the survival of the converter. Therefore, the understanding of voltage variation rules presents a primordial interest. A particular structure of multilevel converter appeared in the early nineties: the imbricated cell topology. The work proposed in the paper deals with the study of dynamic behaviour about capacitors making this kind of converter. The proposed analysis is dealt with in an original approach, based on physical and mathematical laws. Variation rules can then be established, allowing the modelling of capacitor charge according to the converter control parameters. This modelling will lead to some particular phenomena concerning the charge of capacitors, inducing a malfunction of running in the converter. The results obtained by modelling and simulation is proved with an experiment.