A high power-quality, three-phase utility interface

This paper presents a new three-phase AC/DC power converter topology that provides a high-power-factor interface to the utility. The circuit topology of the converter is based on the discontinuous mode flyback converter. The objective of this work is to develop the technology for the proposed converter to meet the high-power factor requirements and to serve the demand for an advanced high-power, inexpensive, efficient and small size AC/DC rectifier in the telecommunications market. A laboratory proof-of-concept converter intended for 12.5 kW output was built to investigate the performance of the proposed converter in a practical application. The experimental results verify that the proposed converter achieves a near-unity power factor at the input and a constant voltage at the load side of the interface. However, the efficiency of the converter measured lower than expected. Further study revealed that the low efficiency is due to the adverse effects of the parasitic inductances on the energy transfer to the output. The effects of the parasitics on the converter efficiency are analytically investigated and new optimum design rules are developed, and the results of the analysis are graphically displayed to point to a practically viable and an efficient design of the proposed converter.