The ARCP flying capacitor inverter

Reduction of switching losses is an important issue in development of high power multilevel converters. Improvement of the known soft switching techniques to find application in multilevel topologies is therefore a worth attempt started recently. This paper proposes a new auxiliary circuit for the flying capacitor multilevel converters realizing soft switching conditions for these converters using the auxiliary resonant commutated pole (ARCP) technique. The proposed ARCP auxiliary circuit provides zero-voltage-switching conditions for main switches without any extra voltage and current stresses on the main and auxiliary switches. The auxiliary switches operate in zero-current-switching conditions as in case of ARCP circuit in a two-level converter. All degrees of freedom of space vector modulation remain available, so that any kind of PWM technique and current control strategy can be used without any constraint. The proposed auxiliary circuit operates also similarly for the redundant switching states of multilevel space vector PWM being used for voltage control of flying capacitors. The results obtained from simulation and experimental set-up verify adequate operation of proposed auxiliary circuit