A New Carrier based Precharging Technique for Single-Phase Odd-Level Flying Capacitor Multilevel Converters (FCMCs)

During the start-up procedure of Flying Capacitor Multilevel Converter (FCMC), all the flying-capacitors needs to be charged to the appropriate voltage levels. This paper presents a novel carrier based technique for the precharging of flying-capacitors in single-phase odd-level FCMCs. A new set of modified phase shifted carrier signals are derived for precharging. These carrier signals when compared to zero modulation signal, ensures the synthesisation of sufficient number of zero-voltage switching states of the converter. The proposed precharging technique is detailed using a five-level FCMC which can be generalized further to any odd-level FCMC. An elaborate loss analysis of the proposed precharging technique is presented. Extensive simulation studies are done to validate the claims made and the corresponding results are provided.