A modular single-phase power-factor-correction scheme with a harmonic filtering function

Power supply systems in telecommunication applications employ several parallel-connected ac-to-dc and dc-to-dc power converters. Such a system offers modularity, redundancy, and is easily scalable to higher power levels. Such parallel-connected systems normally consist of several single-phase powerfactor-correction (PFC) stages connected to the same input utility. In this paper, a modular single-phase PFC scheme with an integrated harmonic filtering function is presented. The proposed approach demonstrates that, with suitable modifications to the PFC control, harmonic filtering capability can be added. In other words, the PFC stage can compensate for harmonics generated by other rectifier loads connected to the same ac input terminals. The paper presents an example employing three ac–dc rectifier stages with only one ac–dc rectifier stage with PFC capability. It is shown that one PFC stage with the proposed control can compensate for harmonics generated by the other two uncompensated rectifier stages. Results from a laboratory prototype system demonstrate that the overall system meets the EN 61000-3-2 harmonic limits.