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In this paper we show the existence and multiplicity of positive solutions for a class of elliptic problem of the type $$\begin{aligned} -\,\Delta u+\lambda V(x)u=\mu u^{q-1}+u^{2^*-1},\quad \text{ in } \quad \mathbb {R}^N, \qquad {(P)_{\lambda , \mu }} \end{aligned}$$ -Δu+λV(x)u=μuq-1+u2∗-1,inRN,(P)λ,μ where $$\lambda , \mu >0$$ λ,μ>0 , $$q \in (2,2^*)$$ q∈(2,2∗) and $$V:\mathbb {R}^N \rightarrow...
This paper investigates two converters composed of a five-level H-bridge cell cascaded with a three-level one. Two types of 5-level H-bridges are used, the first one is composed of a NPC leg and a 2-level leg (in the first topology), and the second one is composed of NPC legs only (in the second configuration). In both topologies the 5-level cell is cascaded with a 3-level H-bridge. Both converters...
This paper presents three three-phase AC-DC configurations in which two are unidirectional and have reduced switch count. The investigated topologies have one DC-link and are composed by two converters in series connection through transformers, that process part of the total power, while the conventional converters have two DC-links and a transformer processing all the power. The replacement of switches...
This paper proposes ten alternative drive topologies with reduced number of controlled switches. The topologies are composed by three-level (3L) and two-level (2L) legs combinations. All of them aim to feed a three-phase machine based on the concept of open-end-winding (OEW). Conventional OEW configurations are considered for comparison purposes. The proposed topologies are named accordingly to the...
This paper proposes three topologies of multilevel dynamic voltage restorer (DVR) with application in three-phase systems (balanced and unbalanced) to compensate sags/swells. The topologies use three independent dc-links (one per phase) and each converter is mounted with one three-level NPC leg (3L) and one two-level leg (2L), furnishing a five-level (5L) voltage at its output. This proposed topologies...
This paper investigates the digital implementation of a modulation strategy that can completely remove the low-frequency voltage oscillation, which appears in the neutral point, for all the operating points and for any kind of loads. The implementation is based on a hybrid modulation technique that produces low switching losses and is simple to implement. Losses, average switching frequency, and performance...
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