Análise de desempenho de diferentes estratégias de modulação PWM para conversores de três níveis com diodo de grampeamento

Abstract

Multilevel converters are finding greater increased attention in industry and academic research as one of the preferred choices of electronic power conversion for high-power applications that need to operate at medium voltage levels, mainly due to high demand of power ratings. Several researches are contributing to further improve the performance of multilevel converters, so that energy efficiency attached to good quality of energy with reduced power losses is desired. Thus, new or improved pulse width modulation (PWM) techniques are assisting to improve these requirements. Among of multilevel converters topologies available, the NPC converter (Neutral Point Clamped) is becoming an attractive option in the market and expanding its use in several applications, even as in medium and high voltage systems as well as in the industrial sector and renewable energy systems. The significance of modulation techniques in the performance of multilevel converters has been demonstrated. Due this, several carriers based PWM techniques and space vector PWM techniques suitable for the NPC converter are described, analyzed and evaluated. Detailed simulation studies, applying such modulation techniques, are performed on the PSCAD/EMTDC (Power Systems Computer Aided Design / Electromagnetic Transients including DC) platform. In addition, an algorithm was implemented to simulate the techniques: the conventional space vector scheme and space vector scheme without even order harmonics, developed for a three level NPC converter. With results of this research, it performs an analysis and comparison of the performance between space vector PWM and carrier based PWM schemes, suitable for a three-level NPC converter. The performance comparison is presented and evaluated in relation to the total harmonic distortion (THD), common mode voltage and rms voltage in the converter output.