scholarly journals Prediction of Conducted Emissions in Satellite Power Buses

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Giordano Spadacini ◽  
Flavia Grassi ◽  
Diego Bellan ◽  
Sergio A. Pignari ◽  
Filippo Marliani
Keyword(s):  
Behavioral Model ◽  
Wide Frequency Range ◽  
System Level ◽  
Power Cables ◽  
Power Conditioning ◽  
Frequency Spectra ◽  
Unit Level ◽  
Modeling Methodology ◽  
Multiconductor Transmission Line ◽  
Conducted Emissions

This work reports a modeling methodology for the prediction of conducted emissions (CE) in a wide frequency range (up to 100 MHz), which are generated by dc/dc converters and propagate along the power buses of satellites. In particular, the dc/dc converter seen as a source of CE is represented by a behavioral model, whose parameters can be identified by two unit-level experimental procedures performed in controlled test setups. A simplified multiconductor transmission-line (MTL) model is developed to account for the propagation of CE in shielded bundles of twisted-wire pairs used as power cables. The whole power system is represented by the interconnection of the circuit models of dc/dc converters, cables, and Power Conditioning and Distribution Unit (PCDU). By solving the obtained network, frequency spectra of CE can be predicted. Experimental results are reported to substantiate the accuracy of the proposed unit-level dc/dc converter model and the MTL model of cables. Finally, a system-level test setup composed of three dc/dc converters connected to a PCDU is considered, and predicted CE are compared versus experimental measurements.

scholarly journals High-Frequency Modeling and Filter Design for PWM Drives with Long Cables

2020 ◽  
Author(s):  
Lei Wang ◽  
Yifan Zhang ◽  
Muhammad Saqib Ali ◽  
Guozhu Chen ◽  
Josep M. Guerrero ◽  
...  
Keyword(s):  
High Frequency ◽  
Small Volume ◽  
Filter Design ◽  
Wide Frequency Range ◽  
Drive System ◽  
Power Cables ◽  
Frequency Range ◽  
Differential Mode ◽  
Proper Filter ◽  
Peak Value

Aiming for the problems emerging in the PWM drive system with long cables, accurate modeling of power cables is the premise to predict and analyze the relevant phenomenon, and a proper filter design is the key solution to these problems. This paper proposes high-frequency cable models to represent the frequency-dependent characteristics, especially for the high-frequency resistance of the cable that is an easily overlooked factor but determines the damping of overvoltage. The proposed models can be used for accurately representing the cable parameters in a wide frequency range, and correctly simulating the differential mode (DM) overvoltage and common mode (CM) current, including the peak value, oscillation frequency and damping of the transient waveform. In addition, improved filter networks are proposed to suppress the DM voltage and CM current, with the merit of low losses, small volume and an excellent ability of suppressing overvoltage. The proposed cable models and the filter design have been validated in a 750W PWM drive system with 200m power cables.

scholarly journals Multi-Level Modeling Methodology for Optimal Design of Electric Machines Based on Multi-Disciplinary Design Optimization

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4173
Author(s):  
Zehua Dai ◽  
Li Wang ◽  
Lexuan Meng ◽  
Shanshui Yang ◽  
Ling Mao
Keyword(s):  
Power Systems ◽  
Design Optimization ◽  
Synchronous Generator ◽  
Electric Machines ◽  
Modeling Method ◽  
System Level ◽  
Superior Performance ◽  
Efficient Design ◽  
Modeling Methodology ◽  
Multi Level

The transportation sector is undergoing electrification to gain advantages such as lighter weight, improved reliability, and enhanced efficiency. As contributors to the safety of embedded critical functions in electrified systems, better sizing of electric machines in vehicles is required to reduce the cost, volume, and weight. Although the designs of machines are widely investigated, existing studies are mostly complicated and application-specific. To satisfy the multi-level design requirements of power systems, this study aims to develop an efficient modeling method of electric machines with a background of aircraft applications. A variable-speed variable-frequency (VSVF) electrically excited synchronous generator is selected as a case study to illustrate the modular multi-physics modeling process, in which weight and power loss are the major optimization goals. In addition, multi-disciplinary design optimization (MDO) methods are introduced to facilitate the optimal variable selection and simplified model establishment, which can be used for the system-level overall design. Several cases with industrial data are analyzed to demonstrate the effectiveness and superior performance of the modeling method. The results show that the proposed practices provide designers with accurate, fast, and systematic means to develop models for the efficient design of aircraft power systems.

Amorphous Silicon Carbide (α-SiC) Thin Square Membranes for Resonant Micromechanical Devices

2012 ◽  
Vol 717-720 ◽  
pp. 533-536 ◽  
Author(s):  
Andrew C. Barnes ◽  
Christian A. Zorman ◽  
Philip X.L. Feng
Keyword(s):  
Silicon Carbide ◽  
Amorphous Silicon ◽  
Room Temperature ◽  
Wide Frequency Range ◽  
Membrane Thickness ◽  
Quality Factors ◽  
Frequency Spectra ◽  
Amorphous Silicon Carbide ◽  
Resonant Modes ◽  
Micromechanical Devices

We report an initial experimental exploration of engineering very thin, suspended amorphous silicon carbide (a-SiC) membranes into vibrating micromechanical devices. We show that micromachined a-SiC thin square membranes can make interesting multiple-mode flexural resonators, with frequency spectra exhibiting many measurable resonant modes over a wide frequency range (100kHz–10MHz) in the low radio frequency (RF) bands. Initial demonstration and preliminary data suggest interesting and rich dynamical, nonlinear, and dissipative properties in these micromechanical resonances. Specifically, for instance, at room temperature (T≈300K) and in moderate vacuum (e.g., ~20mTorr), resonant modes of an a-SiC square membrane (thickness: t≈1.5µm, size: 1mm×1mm) are observed in the ~100kHz–5MHz range, with measured quality factors (Q’s) in the range of ~2,500–9,000.

scholarly journals Behavioral Modeling Paradigm for DC Nanogrid Based Distributed Energy Systems

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7904
Author(s):  
Muhammad Saad ◽  
Yongfeng Ju ◽  
Husan Ali ◽  
Sami Ullah Jan ◽  
Dawar Awan ◽  
...  
Keyword(s):  
Renewable Energy Sources ◽  
Storage System ◽  
Energy Systems ◽  
Behavioral Model ◽  
Operating Conditions ◽  
Behavioral Modeling ◽  
System Level ◽  
Distributed Energy ◽  
New Paradigm ◽  
Large Signal

The remarkable progress of power electronic converters (PEC) technology has led to their increased penetration in distributed energy systems (DES). Particularly, the direct current (dc) nanogrid-based DES embody a variety of sources and loads, connected through a central dc bus. Therefore, PECs are required to be employed as an interface. It would facilitate incorporation of the renewable energy sources and battery storage system into dc nanogrids. However, it is more challenging as the integration of multiple modules may cause instabilities in the overall system dynamics. Future dc nanogrids are envisioned to deploy ready-to-use commercial PEC, for which designers have no insight into their dynamic behavior. Furthermore, the high variability of the operating conditions constitute a new paradigm in dc nanogrids. It exacerbates the dynamic analysis using traditional techniques. Therefore, the current work proposes behavioral modeling to perform system level analysis of a dc nanogrid-based DES. It relies only on the data acquired via measurements performed at the input–output terminals only. To verify the accuracy of the model, large signal disturbances are applied. The matching of results for the switch model and its behavioral model verifies the effectiveness of the proposed model.

Neoclassical Realist Analyses of Foreign Policy

2017 ◽  
Author(s):  
Michiel Foulon
Keyword(s):  
Foreign Policy ◽  
International System ◽  
System Level ◽  
Neoclassical Realism ◽  
State Behavior ◽  
Unit Level ◽  
Policy Choices ◽  
Theoretical Approaches ◽  
Domestic Level ◽  
Level Of Analysis

Neoclassical realism offers insights into why particular foreign policy choices are made, and under what systemic conditions unit-level factors are likely to intervene between systemic stimuli and state behavior. Neoclassical realism brings a multilevel framework that combines both systemic incentives and mediating unit-level variables to arrive at conclusions about foreign policy choices in particular cases. It sets the relative distribution of capabilities in the international system as the independent variable and adds mediating variables at the unit level of analysis. Variables at the domestic level of analysis, such as the role of ideology, the foreign policy executive’s perceptions, resource extraction, and domestic institutions, add explanatory power to system-level approaches. Neoclassical realism accounts for state behavior in a way that a more parsimonious systems-level theory is unable to achieve. But this rich theoretical framework also faces controversies and criticisms: Is neoclassical realism distinct from other theories and what is its added value? Neoclassical realism overlaps only to a small extent with alternative theoretical approaches. The domestic level of analysis dominates Foreign Policy Analysis (a subfield of International Relations). Unit-level variables suffice to explain state behavior in bottom-up approaches, and opening the structure of the international system for fundamental rethinking is central to constructivism. Neither explains the system-level conditions under which unit-level variables mediate between systemic stimuli and foreign policy. Neoclassical realism analyzes and explains a given foreign policy that more parsimonious or alternative theoretical approaches cannot.

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