Power density

About: Power density is a research topic. Over the lifetime, 9534 publications have been published within this topic receiving 197264 citations. The topic is also known as: volumic power & volume power density.

Energy harvesting using a PZT ceramic multilayer stack

Abstract: In this paper, the interdisciplinary energy harvesting issues on piezoelectric energy harvesting were investigated using a ‘33’ mode (mechanical stress and/or electric field are in parallel to the polarization direction) lead zirconate titanate multilayer piezoelectric stack (PZT-Stack). Key energy harvesting characteristics including the generated electrical energy/power in the PZT-Stack, the mechanical to electrical energy conversion efficiency, the power delivered from the PZT-Stack to a resistive load, the electrical charge/energy transferred from the PZT-Stack to a super-capacitor were systematically addressed. Theoretical models for power generation and delivery to a resistive load were proposed and experimentally affirmed. In a quasi-static regime, 70% generated electrical powers were delivered to matched resistive loads. A 35% mechanical to electrical energy conversion efficiency, which is more than 4 times higher than other reports, for the PZT-Stack had been obtained. The generated electrical power and power density were significantly higher than those from a similar weight and size cantilever-type piezoelectric harvester in both resonance and off-resonance modes. In addition, our study indicated that the capacitance and piezoelectric coefficient of the PZT-Stack were strongly dependent on the dynamic stress. (Some figures may appear in colour only in the online journal)

Laser-induced damage of optical materials

Abstract: Glossary of Terms OPTICAL EFFECTS AT LOW POWER/ENERGY LEVELS Introduction Electromagnetic Theory Dispoersion Reflectance and Transmittance Reflectance and Absortance of a Conducting Surface Molecular Polarizability Absorption Scatter Analysis of R, T, A and S Measurements OPTICAL EFFECTS AT MEDIUM POWER/ENERGY LEVELS Introduction Absorption Raman Scattering Brillouin Scattering Harmonic Generation Self-Focusing DAMAGE THEORY Introduction Thermal Mechanisms Dielectric Processes Testing Regimes Time of Damage Damage Morphology SURFACES AND SUB-SURFACES Introduction Surfaces Sub-Surface COATINGS Introduction Coating Technology Measurements and Morphology of Coated Surfaces Coating Design Damage to Dielectric Coatings SPECIAL TOPICS Ambient Atmosphere/Gases Liquids Photodetectors Fibre Optics Scaling Laws Significance of the Units of Measurement MEASUREMENT TECHNIQUES Introduction Measurement of Power, Power Density, Energy, and Energy Density Laser-Induced Damage Threshold Measurement of Optical Characteristics Surface Measurement and Specification Other Measurements APPENDICES References Index

48-V Voltage Regulator Module With PCB Winding Matrix Transformer for Future Data Centers

Abstract: Efficient power delivery architecture is gaining more attention in the design of future generations of data centers in order to minimize the ever increasing trend of power consumption Silicon-based power delivery architectures and designs have already reached a level of maturity in terms of efficiency and density Recent studies indicate that 48-V voltage regulator modules (VRMs), instead of 12-V VRMs, are deemed a more efficient and cost effective architecture In this paper a Gallium Nitride (GaN) based design of a two-stage solution is proposed The first stage is a 48 V/12 V-250 W LLC converter with a matrix transformer design operating at 16 MHz with a peak efficiency of 973% and a power density of 870 W/in3 The second stage is a 12/18 V multiphase buck converter which can be either a conventional silicon-based or a GaN-based design with a higher operating frequency and power density Furthermore, in this proposed two-stage architecture, a novel light load improvement mechanism is proposed by dynamically changing the bus voltage from 12 to 6 V during light load by which the system can achieve a more than 8% efficiency improvement

Impact of Power Density Maximization on Efficiency of DC–DC Converter Systems

Abstract: The demand for decreasing costs and volume leads to a constantly increasing power density of industrial converter systems. In order to improve the power density, further different aspects, like thermal management and electromagnetic effects, must be considered in conjunction with the electrical design. Therefore, a comprehensive optimization procedure based on analytical models for minimizing volume of DC-DC converter systems has been developed at the power electronic systems laboratory of the Swiss Federal Institute of Technology (ETH Zurich). Based on this procedure, three converter topologies-a phase-shift converter with current doubler and with capacitive output filter and a series-parallel resonant converter-are optimized with respect to power density for a telecom supply (400 V/48 V). There, the characteristic of the power density, the efficiency, and the volume distribution between the components as functions of frequency are discussed. For the operating points with maximal power density, the loss distribution is also presented. Furthermore, the sensitivity of the optimum with respect to junction temperature, cooling, and core material is investigated. The highest power density is achieved by the series-parallel resonant converter. For a 5-kW supply, a density of approximately 12 kW/L and a switching frequency of ca. 130 kHz are obtained.