A switched-mode three-phase three-level telecommunications rectifier

Abstract

This paper presents a high power factor three-phase three-level 6 kW rectifier. The rectifier is composed of two stages connected in series: a three-switch three-level pulse-width modulated (PWM) preregulator and a neutral-point-clamped zero-voltage-switching PWM DC-DC converter (NPC-ZVS-PWM). The structures chosen for both stages have a common capacitive center point that allows the three-level operation and a low blocking-voltage stress on all the power switches (half of DC-link voltage). The reduction of blocking voltage allows the use of low cost and low loss power devices, increasing the efficiency and the power density with reduced production cost.