A New Modular Multilevel Converter Topology Using Flying Ultra-Capacitor and Cascaded H-bridges

This paper presents a new multilevel converter topology based on cascaded h-bridges with ultra-capacitor sub-DC voltage step generator. This is achieved by using a controlled latching switch array (LSA). Cascading multiple h-bridge units yields higher level counts with reduced dV/dt rating on individual switches while also making the system modular. Each module has a separate DC source (SDCS), which gets smaller as the number of h-bridge modules increases. The system is operated at low switching frequencies as multiple levels reduce total harmonic distortion (THD) of the output waveforms, while also reducing radio frequency interference (RFI). The increased h-bridge count helps in reducing the size of individual DC sources, and also the dV/dt rating of individual switches required is low. The proposed topology can be used in renewable energy integration with grid such as solar photovoltaic systems, electric vehicles etc.