Bi-directional switch packaging for higher power matrix converters

2003 ◽  
Author(s):  
D. Chamund
Keyword(s):  
Matrix Converters ◽  
Higher Power ◽  
Power Matrix

scholarly journals Modulation Methods for Direct and Indirect Matrix Converters: A Review

Electronics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 812
Author(s):  
Diogo Varajão ◽  
Rui Esteves Araújo
Keyword(s):  
Power Flow ◽  
Matrix Converter ◽  
Matrix Converters ◽  
Ac Power ◽  
Higher Power ◽  
Vector Modulation ◽  
Modulation Methods ◽  
Bidirectional Power Flow ◽  
Significant Attention ◽  
Academic Sector

Matrix converters (MCs) allow the implementation of single-stage AC/AC power conversion systems (PCS) with inherent bidirectional power flow capability. By avoiding the typical DC-link capacitor, MCs have the potential to achieve higher power density with a more reliable operation and less maintenance when compared with conventional two-stage AC/DC/AC PCS. For these reasons, matrix converters have been receiving significant attention from the academic sector but have not yet been implemented on a large industrial scale. This article reviews the Direct Matrix Converter (DMC) and the Indirect Matrix Converter (IMC) along with the respective actual and most important modulation methods. Simulation results are provided to validate the theoretical analysis and to get a deep insight about the implementation of space vector modulation (SVM) and respective switching pattern generator.

Physical Fitness and Resting EEG in Children With Attention Deficit Hyperactivity Disorder

2015 ◽  
Vol 29 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Ching-Wen Huang ◽  
Chung-Ju Huang ◽  
Chiao-Ling Hung ◽  
Chia-Hao Shih ◽  
Tsung-Min Hung
Keyword(s):  
Attention Deficit Hyperactivity Disorder ◽  
Physical Fitness ◽  
Attention Deficit ◽  
Resting State ◽  
Self Control ◽  
Children With Adhd ◽  
Hyperactivity Disorder ◽  
Higher Power ◽  
Eyes Open ◽  
The Relationship

Children with attention deficit hyperactivity disorder (ADHD) are characterized by a deviant pattern of brain oscillations during resting state, particularly elevated theta power and increased theta/alpha and theta/beta ratios that are related to cognitive functioning. Physical fitness has been found beneficial to cognitive performance in a wide age population. The purpose of the present study was to investigate the relationship between physical fitness and resting-state electroencephalographic (EEG) oscillations in children with ADHD. EEG was recorded during eyes-open resting for 28 children (23 boys and 5 girls, 8.66 ± 1.10 years) with ADHD, and a battery of physical fitness assessments including flexibility, muscular endurance, power, and agility tests were administered. The results indicated that ADHD children with higher power fitness exhibited a smaller theta/alpha ratio than those with lower power fitness. These findings suggest that power fitness may be associated with improved attentional self-control in children with ADHD.

Duty Cycles for Three-Phase of Three-Phase Matrix Converters

2011 ◽  
Vol 131 (9) ◽  
pp. 1173-1174 ◽  
Author(s):  
Inami Asai ◽  
Takaharu Takeshita
Keyword(s):  
Matrix Converters ◽  
Duty Cycles ◽  
Three Phase

Using graphs to construct a math model of a microcontroller-based system for preset rate control of a flywheel motor to be used in high-dynamics spacecraft

2020 ◽  
pp. 126-134
Author(s):  
Vladimir V. NEKRASOV
Keyword(s):  
Real Time ◽  
Rotation Rate ◽  
Control Function ◽  
Real Time Control ◽  
Math Model ◽  
The Real ◽  
Time Control ◽  
Power Matrix ◽  
High Dynamics ◽  
Stated Problem

Developing a microcontroller-based system for controlling the flywheel motor of high-dynamics spacecraft using Russian-made parts and components made it possible to make statement of the problem of searching control function for a preset rotation rate of the flywheel rotor. This paper discusses one of the possible options for mathematical study of the stated problem, namely, application of structural analysis based on graph theory. Within the framework of the stated problem a graph was constructed for generating the new required rate, while in order to consider the stochastic case option the incidence and adjacency matrices were constructed. The stated problem was solved using a power matrix which transforms a set of contiguous matrices of the graph of admissible solution edge sequences, the real-time control function was found. Based on the results of this work, operational trials were run for the developed control function of the flywheel motor rotor rotation rate, a math model was constructed for the real-time control function, and conclusions were drawn about the feasibility of implementing the results of this study. Key words: Control function, graph, incidence matrix, adjacency matrix, power matrix, microcontroller control of the flywheel motor, highly dynamic spacecraft.

Some consequences of body size

1984 ◽  
Vol 247 (4) ◽  
pp. H495-H507 ◽  
Author(s):  
L. E. Ford
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Metabolic Rate ◽  
Muscle Power ◽  
Weight Ratio ◽  
Single Species ◽  
Hill Climbing ◽  
Proper Size ◽  
Higher Power ◽  
Metabolic Indices

The question of the proper size denominator for metabolic indices is addressed. Metabolic rate among different species is proportional to the 3/4 power of body weight, not surface area. Muscle power also varies with the 3/4 power of weight, suggesting that metabolic rate is determined mainly by muscle power. Power-to-weight ratio, specific metabolic rate, and a number of metabolic periods, including heart rate, all vary inversely with the 1/4 power of body weight. Thus the relative times required for physiological and pathological processes in different species may be estimated from the average resting heart rate for the species. There are not many small humans among athletic record holders in events involving acceleration and hill climbing, as would be expected if they had higher power-to-weight ratios. Thus the relationship between size and metabolic rate in different species should not be applied within the single species of humans. Evidence is reviewed showing that basal metabolic rate in humans is determined mainly by lean body mass.

scholarly journals Numerical and Theoretical Study of Performance and Mechanical Behavior of PEM-FC Using Innovative Channel Geometrical Configurations

2021 ◽  
Vol 11 (12) ◽  
pp. 5597
Author(s):  
Hussein A. Z. AL-bonsrulah ◽  
Mohammed J. Alshukri ◽  
Ammar I. Alsabery ◽  
Ishak Hashim
Keyword(s):  
Fuel Cell ◽  
Cross Section ◽  
Rectangular Channel ◽  
Compressive Load ◽  
Proton Exchange ◽  
Channel Cross Section ◽  
Channel Height ◽  
Cross Sectional ◽  
Triangular Channel ◽  
Higher Power

Proton exchange membrane fuel cell (PEM-FC) aggregation pressure causes extensive strains in cell segments. The compression of each segment takes place through the cell modeling method. In addition, a very heterogeneous compressive load is produced because of the recurrent channel rib design of the dipole plates, so that while high strains are provided below the rib, the domain continues in its initial uncompressed case under the ducts approximate to it. This leads to significant spatial variations in thermal and electrical connections and contact resistances (both in rib–GDL and membrane–GDL interfaces). Variations in heat, charge, and mass transfer rates within the GDL can affect the performance of the fuel cell (FC) and its lifetime. In this paper, two scenarios are considered to verify the performance and lifetime of the PEM-FC using different innovative channel geometries. The first scenario is conducted by adopting a constant channel height (H = 1 mm) for all the differently shaped channels studied. In contrast, the second scenario is conducted by taking a constant channel cross-sectional area (A = 1 mm2) for all the studied channels. Therefore, a computational fluid dynamics model (CFD) for a PEM fuel cell is formed through the assembly of FC to simulate the pressure variations inside it. The simulation results showed that a triangular cross-section channel provided the uniformity of the pressure distribution, with lower deformations and lower mechanical stresses. The analysis helped gain insights into the physical mechanisms that lead to the FC’s durability and identify important parameters under different conditions. The model shows that it can assume the intracellular pressure configuration toward durability and appearance containing limited experimental data. The results also proved that the better cell voltage occurs in the case of the rectangular channel cross-section, and therefore, higher power from the FC, although its durability is much lower compared to the durability of the triangular channel. The results also showed that the rectangular channel cross-section gave higher cell voltages, and therefore, higher power (0.63 W) from the fuel cell, although its durability is much lower compared to the durability of the triangular channel. Therefore, the triangular channel gives better performance compared to other innovative channels.

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