1. Three-Phase Three-Level Reduced Switch Count Isolated AC/DC Neutral-Point Clamped Converter With High-Frequency DC-Link
- Author
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Dutra, Ailton do Egito, Vitorino, Montie Alves, and Correa, Mauricio Beltrao de Rossiter
- Abstract
This article proposes a three-phase three-level reduced switch count isolated AC/DC Neutral Point Clamped (NPC) converter, with high-frequency DC-link, for applications of unidirectional power flow. The studied converter is composed by a reduced switch count NPC (AC-side stage) in series with two isolated pulsating DC/DC converters. In contrast to conventional topologies, no bulky electrolytic capacitors are necessary in the DC-link of the proposed converter, which is its main advantage. A Modified Level-Shifted Pulse Width Modulation (MLSPWM) strategy is adopted, which is able to operate the AC-side stage converter with only one switch commuting in each switching period, while the switches of the isolated pulsating DC/DC converter are commuted with half of the frequency of the AC-side's switches. In order to guarantee the reference load voltage and near-sinusoidal grid currents, a dual-loop control strategy with voltage PI and current resonant PI controllers is used. The proposed converter is compared with a conventional topology in terms of power losses on the semiconductors, global efficiency, and Total Harmonic Distortion (THD) of the grid currents. Experimental results of a down-scaled prototype of the proposed converter in steady-state operation and with load transient are presented to validate the theoretical approach and the efficiency of the control strategy adopted.
- Published
- 2024
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