- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Liquid switchable radial polarization converters made of sculptured thin films
摘要： A radial polarization converter is a super-structured optical retarder that converts a conventional linearly polarized light beam into a structured beam with radial or azimuthal polarization. We present a new type of these sophisticated optical elements, which is made of porous nanostructured sculptured single thin films or multilayers prepared by physical vapor deposition at an oblique angle. They are bestowed with an axisymmetric retardation activity (with the fast axis in a radial configuration). In particular, a Bragg microcavity multilayer that exhibits a tunable transmission peak in the visible range with a retardance of up to 0.35 rad has been fabricated using this methodology. Owing to the highly porous structure of this type of thin films and multilayers, their retardance could be switched off by liquid infiltration. These results prove the possibility of developing wavelength dependent (through multilayer optical design) and switchable (through vapor condensation or liquid infiltration within the pore structure) radial polarization converters by means of oblique angle physical vapor deposition.
关键词： radial polarization converters,q-plates,oblique angle deposition,sculptured thin films
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - High-Efficiency Weight-Optimized Fault-Tolerant Modular Multi-Cell Three-Phase GaN Inverter for Next Generation Aerospace Applications
摘要： The aircraft industry demands a significant increase in terms of efficiency and gravimetric power density of power converters for next generation aerospace applications. Between the two minimum targets, i.e. an efficiency > 98 % and a gravimetric power density > 10 kW/kg, the specification concerning the converter weight is the most challenging to fulfill. Since cooling systems and magnetic components dominate the weight breakdown of conventional converter concepts, multi-cell topologies, enabling improved semiconductors performance and reduced filtering requirements, are foreseen as promising solutions for the power electronics on board of More Electric Aircraft. On the other hand, the necessary simultaneous operation of a high number of cells inevitably limits the reliability of multi-cell converters if redundancy is not provided. In this paper, a favorable scaling trend of power density with respect to reliability, aiming to guarantee fault-tolerant operation without affecting the performance figures, is identified in modular multi-cell converters. Thus, a 45 kW weight-optimized modular multi-cell three-phase inverter featuring a redundant power stage is optimized, achieving an efficiency of 99 % and a gravimetric power density of 22.8 kW/kg.
关键词： Multi-Objective Optimization,Figure of Merit of Power Semiconductors,Power Converters Reliability,Modular Multi-Cell Inverter,More Electric Aircraft
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Comparative Analysis of Non-Isolated and Isolated Type Partial-Power Optimizers for PV-Battery Series Inverter Architecture
摘要： A seamless battery integration with higher power conversion efficiency and lower system power rating can be achieved by adopting the DC-series battery integration topology into a photovoltaic (PV) string inverter system, the PV-battery series inverter. The PV-battery series inverter uses the partial-power processing technique to achieve flexible current control between PV string and battery. In the process of designing the partial-power DC-DC optimizer, different types of DC-DC converters and different size of batteries can be considered, and the system efficiency and the power rating vary based on the system design. This paper presents a comparative analysis of the different type partial-power optimizers for the PV-battery series inverter in residential rooftop applications (< 10kW PV output power, < 500V DC-bus voltage), in consideration of the DC-DC converter topology. Non-isolated and isolated bidirectional DC-DC converters are considered and selection of battery voltage in each case is made to have the optimized system design. The operation of the designed DC-DC optimizer is verified through controller hardware-in-the-loop test.
关键词： pv-battery series inverter,residential rooftop PV application,comparative analysis,non-isolated and isolated bidirectional dc-dc converters,partial-power dc-dc optimizer,PV-battery integration,dc-series
更新于2025-09-23 15:23:52
-
[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - A Design of the Complete Polarization Converter Using Dielectric Periodic Structures
摘要： Polarization converter is used in the applications of the polar SAR observations. There exists coupling between TE and TM modes when plane wave is oblique incident on the surface of dielectric periodic structure, the single TE or TM polarized wave incident will cause TE and TM mixed transmission wave. In some proper incident conditions, complete polarization conversion can be realized between TE and TM mode. In this work, a design of complete polarization converter by using dielectric periodic structure is designed and it is carefully investigated by a method which combines the multimode network theory with the rigorous mode matching method. We revealed TE/TM complete polarization conversion characteristics of dielectric periodic structure, and also analyzed the effects of structure parameters. These investigations provide important guideline for accurate designing new millimeter wave polarization converters.
关键词： dielectric periodic structure,TE/TM converters.,complete polarization convertor
更新于2025-09-23 15:23:52
-
Analysis of Nonlinear Dynamics of a Quadratic Boost Converter Used for Maximum Power Point Tracking in a Grid-Interlinked PV System
摘要： In this paper, the nonlinear dynamics of a PV-fed high-voltage-gain single-switch quadratic boost converter loaded by a grid-interlinked DC-AC inverter is explored in its parameter space. The control of the input port of the converter is designed using a resistive control approach ensuring stability at the slow time-scale. However, time-domain simulations, performed on a full-order circuit-level switched model implemented in PSIM c software, show that at relatively high irradiance levels, the system may exhibit undesired subharmonic instabilities at the fast time-scale. A model of the system is derived, and a closed-form expression is used for locating the subharmonic instability boundary in terms of parameters of different nature. The theoretical results are in remarkable agreement with the numerical simulations and experimental measurements using a laboratory prototype. The modeling method proposed and the results obtained can help in guiding the design of power conditioning converters for solar PV systems, as well as other similar structures for energy conversion systems.
关键词： subharmonic oscillations,DC-DC converters,maximum power point tracking (MPPT),nonlinear dynamics,photovoltaic (PV),quadratic boost
更新于2025-09-23 15:23:52
-
Minimally asymmetric state conversion around exceptional singularities in a specialty optical microcavity
摘要： Exploiting scattering matrix (S-matrix) formalism, a unique route for manipulating the exceptional points (EPs) has been reported in a trilayer open optical microcavity with non-uniform real refractive index. The boundaries of the intermediate index layer are appropriately tapered. The cavity is partially pumped by transverse distribution of a balanced gain-loss profile. With strict restriction of balanced gain-loss, controlling infinitesimally small variation of gain-coefficient with simultaneous tapering parameter an EP has been encountered; which is being encircled in cavity parameter space to study dynamics of the coupled states around the EP in the context of robust selective flip-of-state phenomena with lower-asymmetry in state conversion efficiencies. Such a specialty trilayer microcavity with tunable width is reported for the first time; which turns out to be a specific approach to achieve maximum efficiency in conversion with minimum asymmetry. Considering suitable state-of-the-art techniques, this exclusive proposal may open up a fabrication feasible platform for device level implementation of system control exploiting EPs.
关键词： Microcavity devices,Mode-converters,Exceptional points,Avoided resonance crossing,Optical resonators
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Design and Optimization of a Solar Power Conversion System for Space Applications
摘要： This manuscript details a design method for a 500kW solar power based microgrid system for space applications. The design method utilizes multi-objective optimization with the Genetic Algorithm considering four parameters that characterize solar power based microgrids (battery voltage, PV maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular DC-DC micro-converters, of which four topologies (buck, boost, buck-boost and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56W/kg, with optimized result of 743.7V battery voltage, 439.5W PV maximum power, 182.7V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54W/cm3, a specific power of 3.76W/g, and operated for over 267 hours of 11-minute low temperature cycles from 0oC to -140oC.
关键词： wide band gap semiconductors,microgrids,non-inverting buck-boost,maximum power point trackers,space exploration,photovoltaic systems,design optimization,DC-DC power converters,system-level design,low temperature testing
更新于2025-09-23 15:23:52
-
Novel High Gain, High Efficiency DC–DC Converter Suitable for Solar PV Module Integration With Three-Phase Grid Tied Inverters
摘要： This paper proposes a novel configuration for high gain, high efficiency dc–dc converter comprising a single switch, two intermediate capacitors, and a coupled inductor for low voltage solar PV module fed applications. The high voltage gain is achieved by charging the intermediate capacitors through the coupled inductor in parallel and discharging in series. In a two winding coupled inductor, considered in the presented work, maximum two intermediate capacitors can be integrated with the secondary winding. A passive lossless clamped circuit is also provided in the converter, which recovers the leakage energy to improve the efficiency and alleviate large voltage spike. The structure of the circuit is such that the power device voltage stress is reduced thereby increasing the efficiency. The maximum power point tracking at various irradiation levels is implemented in the proposed converter. Laboratory prototype of a 300-W system with 30–45-V input and 700-V output was built to validate the theoretical claims. All the detailed analysis, simulation, and experimental waveforms are presented. A maximum converter efficiency of around 95% is achieved.
关键词： maximum power point tracking (MPPT),switched capacitor,solar PV,coupled inductor,dc micro-grid,step-up,high efficiency,3-φ inverter,low voltage,high gain,dc–dc converters
更新于2025-09-23 15:22:29
-
Design and Optimization of a Solar Power Conversion System for Space Applications
摘要： This manuscript details a design method for a 500kW solar power based microgrid system for space applications. The design method utilizes multi-objective optimization with the Genetic Algorithm considering four parameters that characterize solar power based microgrids (battery voltage, PV maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular DC-DC micro-converters, of which four topologies (buck, boost, buck-boost and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56W/kg, with optimized result of 743.7V battery voltage, 439.5W PV maximum power, 182.7V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54W/cm3, a specific power of 3.76W/g, and operated for over 267 hours of 11-minute low temperature cycles from 0oC to -140oC.
关键词： low temperature testing,photovoltaic systems,wide band gap semiconductors,maximum power point trackers,design optimization,non-inverting buck-boost,space exploration,system-level design,DC-DC power converters,microgrids
更新于2025-09-23 15:22:29
-
[IEEE IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - D.C., DC, USA (2018.10.21-2018.10.23)] IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - Controller-Hardware-in-the-Loop Testbed for Fast-Switching SiC-Based 50-kW PV Inverter
摘要： The recent advent of wide bandgap power semiconductor devices will lay the path for future power converters. These devices provide the advantage of high switching speed and lower losses. The high cost and high switching speeds of these devices provide a challenge in the development and validation of the fast-switching inverter controls with accuracy comparable to that of a hardware setup. In this paper, a field programmable gate array (FPGA) real-time simulator-based controller-hardware-in-the-loop (CHIL) testbed is used to verify the low-level and advanced inverter controls for fast-switching wide bandgap-based photovoltaic string inverter. The paper also includes development of the CHIL testbed, which is run at a time step of 500 ns in order to implement 20-kHz switching frequency. The developed CHIL testbed is validated through experimental results from a three-phase, 50-kW, 480-VLLrms SiC device-based inverter.
关键词： controller hardware-in-the-loop,high switching frequency,SiC devices,power electronics converters,advanced grid-support functions
更新于2025-09-23 15:22:29