-
[show abstract]
[hide abstract]
ABSTRACT: The object of this paper is to build up a dynamic model of the main propulsion system based on direct torque control (DTC) and analyze its power output limits. The key problem of modeling is to find out the relationships among flux, angular frequency, active power and reactive power, and the result model can be used to guide control parameters design and system operation. The testing simulation of a complete diesel-electric propulsion system using the proposed DTC control strategy is carried out on PSCAD. The power limits are also checked up in this demonstration work.
Advances in Power System Control, Operation and Management (APSCOM 2009), 8th International Conference on; 12/2009
-
[show abstract]
[hide abstract]
ABSTRACT: Microgrid is an innovative way to integrate large amount of renewable distributed generations into electrical distribution system and make the power system more reliable and flexible. The microgrid prototypes suitable for China are proposed firstly, which are divided into two types of urban microgrids and remote microgrids. The two kinds of microgrids have different operation modes, distributed areas, voltage levels, capacities, aims and main microsources types. For further research, the structure and modeling of a microgrid prototype are introduced in detail. Simulation has been done on the platform of MATLAB/Simulink, which enables simulation for both the steady and dynamic characteristics of the three phase microgrid prototype. Various operation modes and possible disturbances have been taken into account during the simulation.
Advances in Power System Control, Operation and Management (APSCOM 2009), 8th International Conference on; 12/2009
-
Huaxiang Yin,
Sunil Kim,
Hyuck Lim, Yosep Min,
Chang Jung Kim,
Ihun Song,
Jaechul Park,
Sang-Wook Kim,
A. Tikhonovsky,
Jaewoong Hyun,
Youngsoo Park
[show abstract]
[hide abstract]
ABSTRACT: Currently, both high-density 3-D stacking nonvolatile (NV) memory and embedded NV memory in advanced systems on panel (SOPs) urgently demand the assistance of new and functional transition metal-oxide materials. This is to overcome serious fabrication issues encountered in the use of conventional Si or poly-crystalline Si materials, as well as to increase storage density with lower process cost. This paper reports the fully functional NV memory structure operated by an ionic amorphous oxide semiconductor with a wide energy band gap (> 3.0 eV) in a Ga<sub>2</sub>O<sub>3</sub>-In<sub>2</sub>O<sub>3</sub>-ZnO (GIZO) system under low process temperature (< 400degC) while being combined with various metal-oxide materials of Al<sub>2</sub>O<sub>3</sub>, GIZO, and Al<sub>2</sub>O<sub>3</sub> as the electron charge's tunneling, storage, and blocking layers, respectively. The different methods of memory programs and, especially, the unique erase characteristics caused by a much wider band gap than Si were intensively being investigated, and as a result, excellent electrical results of a large program/erase window over 3.8 V at a pulse time of 10 ms are achieved.
IEEE Transactions on Electron Devices 09/2008; · 2.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Using the full potential linearized augmented plane wave method based on the spin density functional theory, we investigate the ferromagnetic properties, the electronic structure, and the formation energy of Ga <sub>0.9375</sub>M<sub>0.0625</sub> N ( M= vacancy , Ca). The calculations indicate that both cases prefer ferromagnetic ground state. The magnetic moments mainly come from the N atoms surrounding the defect centers, which are different from the conventional diluted magnetic semiconductor. High formation energy for the Ga vacancy suggests that the defect concentration is too low to result in the ferromagnetic GaN. The formation energy for the two substitutional ( Ca <sub> Ga </sub>, Ca <sub> N </sub>) and two interstitial sites (tetrahedral T , Ca <sub>i-T</sub> and octahedral O, Ca <sub>i- O </sub> ) doped configurations indicates that Ca prefers the substitutional Ga in GaN. The defect concentrations for the Ga <sub>0.9375</sub> Ca <sub>0.0625</sub> N under thermal equilibrium N-rich and N-realistic growth conditions are also discussed, respectively. The calculations show that defect concentration under N-rich condition can readily reach 7%, while under N-realistic growth condition, the maximum defect concentration is as low as 1.71% when the growth temperature increases to 1100 K (melting point of GaN). These results suggest that it would be a little difficult to achieve ferromagnetic state for Ga <sub>0.9375</sub> Ca <sub>0.0625</sub> N using the chemical-equilibrium fabrication method, such as chemical precipitation. Using the same method as that for Cu-doped ZnO [L. H. Ye etal, Phys. Rev. B 73, -
033203 (2006)], the transition temperature of Ga <sub>0.9375</sub> Ca <sub>0.0625</sub> N may be close to room temperature.
Journal of Applied Physics 09/2008; · 2.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, a systematical analysis and PSSs design method is proposed. Participation phasor (PP), and residue phasor (RP) are put forward and compared with each other in virtue of a 16-generator system. Based on PP and RP participation-residue phasor (PRP) and PR-graph are deduced, PR-graph based modal and loci analyses illustrate the interactions between different PSSs. Then analysis based sequential design of PSSs is carried out, in each step PR-graph-based modal analysis proposes a candidate generator, whose PSS will be designed in next step. The effects of new designed PSS on closed-loop system can be found out immediately and conveniently, so the effectiveness of analysis and design can be validated during the design.
Power Engineering Conference, 2007. IPEC 2007. International; 01/2008
