A new six-switch five-level boost-active neutral point clamped (5L-Boost-ANPC) inverter

Abstract

Multilevel converters have seen an increasing popularity in the last decades, due to the increased power ratings, improved power quality, low switching losses, and reduced Electromagnetic Interference (EMI). Among them, the most popular ones are the Neutral Point Clamped (NPC) and the Flying Capacitor (FC) inverter topologies. Different derivatives of the NPC and FC are prevalent in the literature for various applications. However, the main drawback of the NPC and FC topologies is the high dc-link voltage, which has to be more than twice of the grid peak voltage for grid integration. Therefore, a front-end boost dc-dc converter is normally required before the inverter, which decreases the overall efficiency of the system. Single-stage dc-ac power converters with boost capabilities offer an interesting alternative compared to the two-stage approach. Considering this aspect, a novel 5-Level three-phase boost type inverter is introduced in this paper for general-purpose applications (e.g. rolling mills, fans, pumps, marine appliances, mining, tractions, and most prominently grid-connected renewable energy, etc.) which reduces the dc-link voltage requirement to half of the conventional 5-Level NPC, ANPC and 5-Level FC family. Whilst reducing the dc-link voltage requirement, the number of active and passive components are also reduced. The principle of operation and theoretical analysis supported by key simulation and experimental waveforms of a 1.5 kW prototype are presented to prove the concept of the proposed 5L-Boost-ANPC inverter.