High-performance single-phase high-power Active Front-End

A high-performance single-phase active front-end (AFE) for modern railway applications is presented. It can successfully manage the well known trade-off between high power handling and high switching frequency, with regard to utility side effects. The proposed system is made-up by two parallel-connected two-level single-phase AC-DC boost converters with common dc-link capacitor. One is a high-power AC-DC boost converter which behaves as an unitary displacement power factor (DPF) AC-DC rectifier. It works at a low switching frequency and so it is able to control the fundamental components of the line currents only to be aligned with the positive sequence of the node voltages. Adding a low-power high-frequency boost converter working as an active parallel compensator (APC), the whole system also allows a low THD factor at the point of common coupling (PCC).