High Frequency Constraints on the Layout of Wide Band Gap-Based Power Electronic Assemblies Within Shielded Enclosures

Since its integration into power electronic converters, the value proposition of wide band gap semiconductors has yet to be holistically realized due to the high frequency effects associated with increased switching speeds. The United States Navy’s Smart Ship System Design (S3D) platform enables the investigation of wide band gap-based devices in shipboard Medium Voltage Direct Current (MVDC) Integrated Power and Energy Systems (IPES) through the use of metaheuristic model-based scaling laws. These physics-based scaling laws are produced from a virtual prototyping approach which takes into account the discrete building blocks associated with multi-cell based power conversion and distribution equipment and can be used to predict size, weight, losses, cost and reliability. In present practice, the discrete building blocks consist of power electronic assemblies laid out and enclosed within shielded enclosures. In an effort to incorporate the high frequency effects associated wide band gap-based Power Electronic Building Blocks (PEBB) into the virtual prototyping approach, a mathematical model which captures the high frequency effects is formulated in this thesis

High Frequency Constraints on the Layout of Wide Band Gap-Based Power Electronic Assemblies Within Shielded Enclosures

Since its integration into power electronic converters, the value proposition of wide band gap semiconductors has yet to be holistically realized due to the high frequency effects associated with increased switching speeds. The United States Navy’s Smart Ship System Design (S3D) platform enables the investigation of wide band gap-based devices in shipboard Medium Voltage Direct Current (MVDC) Integrated Power and Energy Systems (IPES) through the use of metaheuristic model-based scaling laws. These physics-based scaling laws are produced from a virtual prototyping approach which takes into account the discrete building blocks associated with multi-cell based power conversion and distribution equipment and can be used to predict size, weight, losses, cost and reliability. In present practice, the discrete building blocks consist of power electronic assemblies laid out and enclosed within shielded enclosures. In an effort to incorporate the high frequency effects associated wide band gap-based Power Electronic Building Blocks (PEBB) into the virtual prototyping approach, a mathematical model which captures the high frequency effects is formulated in this thesis

Nanocrystalline semiconductors: synthesis, properties, and perspectives

The preparation of hollow particles of ZnO by calcination of hydrozincite coated poly(styrene) beads is reported. Synthetic studies have been performed on such polymer/inorganic composite precursors in order to establish the optimum conditions for the preparation of the ZnO particles. The morphological properties of the powders were characterised by optical microscopy and scanning electron microscopy. The micrometric ZnO particles show morphological characteristics related to the template used in their preparation

Indirect and direct energy gaps in the Kondo semiconductor YbB12

Optical conductivity [$\sigma(\omega)$] of the Kondo semiconductor YbB$_{12}$ has been measured over wide ranges of temperature ($T$=8$-$690 K) and photon energy ($\hbar \omega \geq$ 1.3 meV). The $\sigma(\omega)$ data reveal the entire crossover of YbB$_{12}$ from a metallic electronic structure at high $T$ into a semiconducting one at low $T$. Associated with the gap development in $\sigma(\omega)$, a clear onset is newly found at $\hbar\omega$=15 meV for $T \leq$ 20 K. The onset energy is identified as the gap width of YbB$_{12}$ appearing in $\sigma(\omega)$. This gap in \sigma(\omega)$is interpreted as the indirect gap, which has been predicted in the band model of Kondo semiconductor. On the other hand, the strong mid-infrared (mIR) peak observed in$\sigma(\omega)$ is interpreted as arising from the direct gap. The absorption coefficient around the onset and the mIR peak indeed show characteristic energy dependences expected for indirect and direct optical transitions in conventional semiconductors.Comment: 4 pages, 3 figures, submitted to J. Phys. Soc. Jp