Active three-phase rectifier system using a “Flying” Converter Cell

Many applications require three-phase rectifier circuits with high input current quality (THD
_i
less than 5%) and a power factor above 0.95 which cannot be achieved by application of simple and robust passive rectifier bridges. Active rectifier circuits are able to fulfill these requirements but existing passive rectifier systems can typically not be extended to these topologies. In this work a novel family of three-phase rectifier systems using a “Flying” Converter Cell is proposed which allows the extension of an existing passive rectifier to a low-harmonic rectifier circuit. The operating principle is discussed, design guidelines based on the calculated current stress of the rectifier circuit are derived and possible operating modes are addressed. The proper operation of the proposed topology is finally demonstrated by simulation of a 170kW rectifier.