Unity power factor operation of three-phase AC-DC converter based on modular approach for telecom applications

High power telecommunication power supply systems consist of a three-phase switch mode converter followed by a dc-dc converter to supply 12kW SMPS. These rectifiers draw significant harmonic currents from the utility, resulting in poor input power factor with high total harmonic distortion (THD). In this paper, a three-phase ac-dc converter based on modular approach is proposed for telecommunication applications. The proposed system is formed by three single-phase modules with series connected dc outputs to increase the power level. The series connection of converter yields balanced three phase currents and galvanic isolation with the use of a high frequency transformer, and provides 6-pulse rectification, both together resulting in a smaller output filter components. A design example and simulation results are presented to validate the model of the proposed three-phase 12-kW SMPS converter.