Dynamic modeling and analysis of single-stage boost inverters under normal and abnormal conditions

Inverters play key roles in connecting sustainable energy (SE) sources to the local loads and the ac grid. Although there has been a rapid expansion in the use of renewable sources in recent years, fundamental research, on the design of inverters that are specialized for use in these systems, is still needed. Recent advances in power electronics have led to proposing new topologies and switching patterns for single-stage power conversion, which are appropriate for SE sources and energy storage devices. The current source inverter (CSI) topology, along with a newly proposed switching pattern, is capable of converting the low dc voltage to the line ac in only one stage. Simple implementation and high reliability, together with the potential advantages of higher efficiency and lower cost, turns the so-called, single-stage boost inverter (SSBI), into a viable competitor to the existing SE-based power conversion technologies.^ The dynamic model is one of the most essential requirements for performance analysis and control design of any engineering system. Thus, in order to have satisfactory operation, it is necessary to derive a dynamic model for the SSBI system. However, because of the switching behavior and nonlinear elements involved, analysis of the SSBI is a complicated task.^ This research applies the state-space averaging technique to the SSBI to develop the state-space-averaged model of the SSBI under stand-alone and grid-connected modes of operation. Then, a small-signal model is derived by means of the perturbation and linearization method. An experimental hardware set-up, including a laboratory-scaled prototype SSBI, is built and the validity of the obtained models is verified through simulation and experiments. Finally, an eigenvalue sensitivity analysis is performed to investigate the stability and dynamic behavior of the SSBI system over a typical range of operation. ^

Spatial Articulations of Race, Desire, and Belonging in Western North Carolina

The sociocultural mythology of the South homogenizes it as a site of abjection. To counter the regionalist discourse, the dissertation intersects queer sexualities with gender and race and focuses on exploring identity and spatial formation among Black lesbian and queer women. The dissertation seeks to challenge the monolith of the South and place the region into multiple contexts and to map Black geographies through an intentional intersectional account of Black queer women. The dissertation utilizes qualitative research methods to ascertain understandings of lived experiences in the production of space. The dissertation argues that an idea of Progress has been indoctrinated as a synonym for the lgbtq civil rights movement and subsequently provides an analysis of progress discourses and queer sexualities and political campaigns of equality in the South. Analyses revealed different ways to situate progress utilizing the public contributions of three Black women interviewed for the dissertation. Moreover, the dissertation utilizes six Black queer and lesbian women to explain the multifarious nature of identities and their construction in place. Black queer and lesbian women produce spaces that deconstruct the normativity of stasis and physicality, and the dissertation explores the consequential realities of being a body in space. These consequences are particularly highlighted in the dissertation by discussions of the processes of racialization in the bounded and unbounded senses of space and place and the impacts of religious institutions, specifically Christianity. The dissertation concluded that no space is without complication. Other considerations should be made in the advancement of alleviating oppression deeply embedded in United States landscapes. Black women’s geographies offer epistemological and ontological renderings that enrich analyses of space, place, and landscape. The dissertation also concludes that Black women’s bodies represent sites for the production of geographic knowledge through narrating their spaces of material trajectories of interlocking, multiscalar lives.