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Loss-Separation Study on Silica-insulated Gas-atomized Fe-Si-Al Soft Magnetic Composites
T. T. Xu,B. W. Zhang,Z. Shi,W. W. Guan,K. Wan,X. Y. Shi,W. Liu,H. L. Su,Z. Q. Zou,Y. W. Du 한국자기학회 2020 Journal of Magnetics Vol.25 No.2
Fe-Si-Al soft magnetic composites were composed of gas-atomized Fe-9.6wt.%Si-5.4wt.%Al alloy powders insulated with silica nanoparticles. The influence of silica insulation content on the core’s magnetic properties was studied. It was found that increasing the silica mass ratio deteriorated the effective permeability and core loss in the frequency range of 40-120 kHz, while improved the quality factor at 100 kHz and DC-bias performance. The effective demagnetizing field reflected by density and the core’s volume resistivity may cause the variations of these magnetic parameters. Loss separation fitting was performed using the Bertotti formula, indicating that silica insulation increased the hysteresis loss and reduced the eddy-current loss. The hysteresis loss took over at the frequency lower than 120 kHz in this work. With increasing the frequency, the eddy-current loss grew more quickly than the hysteresis loss. Therefore, different methods should be adopted to reduce the core loss according to the core’s application frequency.
FUEL PROPERTIES AND EMISSIONS CHARACTERISTICS OF ETHANOL-DIESEL BLEND ON SMALL DIESEL ENGINE
B. Y. XU,Y. L. QI,W. B. ZHANG,S. L. CAI 한국자동차공학회 2007 International journal of automotive technology Vol.8 No.1
Phase separation and low cetane number are the main barriers to the large-scale use of ethanol-diesel blend fuel on small diesel engines. In this paper, an additive package is designed on the basis of the blended fuel properties to overcome these limitations. The experiments show that the solubility of ethanol in diesel is evidently increased by adding 1~2% (in volume) of the additive package and the flammability of ethanol-diesel blend fuel with the additive has reached the neat diesel level under the cold start conditions. Effects of the ethanol content in diesel on fuel economy, combustion characteristics, and emission characteristics are also investigated with the ethanol blend ratios of 10%, 20% and 30%. The increase in ethanol content shows that the specific fuel consumption and the brake thermal efficiency are both gradually increased compared to neat diesel. The soot concentrations of the three blended fuels are all greatly lower than that of neat diesel. NOx emission is increased with an increase in the engine load and is reduced with the increase in the ethanol blend ratio under a high load.
Modeling and Electromagnetic Transient (EMT) Simulation of a Dual Active Bridge DC-DC Converter
W. M. Gong,C. Wang,Z. Zhu,S. K. Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The dual active bridge (DAB) DC-DC converter is the core link of a power electronic transformer (PET). With the development of PETs toward medium- and high-voltage applications, more DAB modules are adopted. However, conventional Electromagnetic Transient (EMT) simulation for a multi-switch circuit is quite time consuming. In this paper digest, a modified constant admittance method has been developed for modeling of an isolated DAB. By reducing the expense of admittance matrix reconstruction and related iterative operation at switching instant, the simulation efficiency has been improved significantly, and the new model becomes more suitable for a real-time simulation algorithm. Meanwhile, time domain simulations are given, which show that the proposed method can keep the same accuracy as the conventional model.
A NOVEL TECHNIQUE OF N2O-TREATMENT ON NH3-NITRIDED OXIDE FOR FABRICATING GATE OXIDE IN NMOSFET`S
Xu,ZEng,Lai,P. T.,Ng,W. T. 대한전자공학회 1995 ICVC : International Conference on VLSI and CAD Vol.4 No.1
a new technique of N₂O treatment on NH₃-nitrided oxide is used to prepare thin gate oxide. Experiments on MOS capacitors and nMOSFET's shows that N₂O treatment is superior to conventional reoxidation step in suppressing electron trapping and interface trap creation under high-field stress.