Wide input voltage range high power density high efficiency 10 kW three-phase three-level unity power factor PWM rectifier

In this paper the current stresses on the power components of a direct three-phase boost-type unity power factor rectifier are analysed in order to provide a basis for a system design under restriction of the height to 2-U. The conduction losses of the power semiconductors are calculated using analytical approximations of the average and RMS values of the component currents. The switching losses are taken from experimental investigations where a novel turn-on snubber has been employed. Based on this data an overview of the estimated power losses is given for a rectifier system of 10.5 kW/800 VDC output for 320 V/400 V/480 V/530 V (RMS, line-to-line) mains voltage. Corresponding efficiency figures are calculated and the improvement achieved by the turn-on snubber as compared to hard switching is determined. The snubber topology and operating principle is discussed in detail. Finally, the theoretical results are verified by experimental investigation of a system prototype.