Optimization of soft-switched Flying Capacitor Multi-level converters applied to STATCOMs

To realize high power density and cost effective STATCOMs, transformer-less and filter-less designs are desirable. In this paper, a Flying Capacitor Multi-level (FCML) converter is selected and designed for a 6.6 kV five-level STATCOM. To decrease size of the flying capacitor by increasing a switching frequency, the Auxiliary Resonant Commutated Pole (ARCP) Converter is used, and their parameters are optimized based on loss-implemented simulation. In addition, effect of voltage ripple upon switching energy is discussed, and difference between hard-switched converter and ARCP converter is presented. Finally, the total losses and costs of the hard-switched and soft-switched five-level FCML converter is compared.