Performance analysis in terms of line current harmonic injection and DC bus output voltage regulation of two three phase boost rectifiers operating under unbalanced load

In this paper, the authors present a comparative study between two three-phase boost rectifier topologies. The topologies considered are three-level (18 switches) and two-level (6 switches) converters. The neutral point of the three-phase source is connected to the midpoint of the DC bus to provide a zero sequence current path. The comparison is carried out for both balanced and unbalanced load connected to the centre tap of the DC bus. The control of unbalanced voltage with the injection of the zero sequence current is achieved using the PWM technique. The THD of line-currents, efficiency and power factor are compared for a 25 kW system operating at 3 kHz. Simulation results obtained by the power system blockset (PSB) tool for both steady state and dynamical operations are presented and analysed.