Novel bidirectional universal 1-phase/3-phase-input unity power factor differential AC/DC converter

A common 400 V dc bus for industrial motor drives advantageously allows the use of high-performance 600 V power semiconductor technology in the inverter drive converter stages and to lower the rated power of the supplying rectifier system. Ideally, this supplying rectifier system features unity power factor operation, bidirectional power flow and nominal power operation in the three-phase and the single-phase grid. This paper introduces a novel bidirectional universal single-/three-phase-input unity power factor differential ac-dc converter suitable for the above mentioned requirements. The basic operating principle and conduction states of the proposed topology are derived and discussed in detail. Then, the main power component voltage and current stresses are determined and simulation results in PLECS are provided. The concept is verified by means of experimental measurements conducted in both three-phase and single-phase operation with a 6 kW prototype system employing a switching frequency of 100 kHz and 1200 V SiC power semiconductors.