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Gong B.,Wuhan Institute of Marine Electrical Propulsion | Cheng S.,Huazhong University of Science and Technology
Lecture Notes in Electrical Engineering

The neutral point (NP) voltage variation is studied; the relationship between NP voltage variation and the overlap is analyzed, in this paper. And a new SPWM control method for three-level (3L) inverter is proposed. A closed loop system is built by altering the displacement of the carriers in the vertical direction in the proposed method, and the control structure is simple. It is easy to make the NP voltage balance by adjusting the overlap. Simulation results indicate that the proposed method can get a good NP voltage control effect. © Springer-Verlag Berlin Heidelberg 2016. Source

Xiong T.,Wuhan Institute of Marine Electrical Propulsion
Corrosion and Protection

Research progress of electroless Ni-P-PTFE composite coatings at home and abroad in recent years is reviewed. The effects of surfacant, temperature, pH, dispersing method of PTFE on the deposition behavior of electroless composite films are focused. The fricton-wearability and corrosion resistance of composite coatings are discussed. The existing problems and furture development of electroless Ni-P-PTFE are indicated. Source

Zou L.,CAS Shanghai Advanced Research Institute | Fan J.,Wuhan Institute of Marine Electrical Propulsion | Zhou Y.,CAS Shanghai Advanced Research Institute | Wang C.,CAS Shanghai Advanced Research Institute | And 3 more authors.
Nano Research

The development of cost-effective oxygen reduction reaction (ORR) catalysts with a high methanol tolerance and enhanced durability is highly desirable for direct methanol fuel cells. This work focuses on the conversion of PtNi nanoparticles from a disordered solid solution to an ordered intermetallic compound. Here the effect of this conversion on ORR activity, durability, and methanol tolerance are characterized. X-ray diffraction and transmission electron microscopy results confirm the formation of ordered PtNi intermetallic nanoparticles with high dispersion and a mean particle size of about 7.6 nm. The PtNi intermetallic nanoparticles exhibited enhanced mass and specific activities toward the methanol-tolerant ORR in pure and methanol-containing electrolytes. The specific activity of the ORR at 0.85 V on the PtNi intermetallic nanoparticles is almost 6 times greater than on commercial Pt/C and 3 times greater than on disordered PtNi alloy. Durability tests indicated a minimal loss of ORR activity for PtNi intermetallic nanoparticles after 5,000 potential cycles, whereas the ORR activity decreased by 28% for disordered PtNi alloy. The enhanced methanoltolerant ORR activity and durability may be attributed to the structural and compositional stabilities of the ordered PtNi intermetallic nanoparticles compared relative to the stabilities of the disordered PtNi alloy, strongly suggesting that the PtNi intermetallic nanoparticles may serve as highly active and durable methanol-tolerant ORR electrocatalysts for practical applications. [Figure not available: see fulltext.] © 2015, Tsinghua University Press and Springer-Verlag Berlin Heidelberg. Source

Wang Q.-D.,China University of Mining and Technology | Zhang W.,Wuhan Institute of Marine Electrical Propulsion
RSC Advances

This work reports a systematic ab initio and chemical kinetic study of the rate constants for hydrogen atom abstraction reactions by hydrogen radical on the isomers of unsaturated C6 methyl esters. Geometry optimizations and a frequency calculations of all of the species involved, as well as the hindrance potential descriptions for reactants and transition states have been performed at the B3LYP/6-311G(2d,d,p) level of theory implemented in the composite CBS-QB3 method. The intrinsic reaction coordinate (IRC) calculations are performed to verify that the transition states are the right minima connecting the reactants and the products. The hindered rotor approximation has been used for the low frequency torsional modes in both reactants and transition states. The high-pressure limit rate constants for every reaction channel in certain methyl ester fuel molecules are calculated via conventional transition-state theory with the asymmetric Eckart method for quantum tunneling effect by using the accurate potential energy information obtained with the CBS-QB3 method. The individual rate constants at different reaction sites for all the methyl esters in the temperature range from 500 to 2500 K are calculated and fitted to the modified three parameters Arrhenius expression using least-squares regression. Further, a branching ratio analysis for each reaction site has also been investigated for all of the methyl esters. To the best our knowledge, it is the first systematic theoretical studies to investigate the influence of the double bond on the elementary reaction kinetics of methyl esters. This work not only provides accurate reaction rate coefficients for combustion chemical kinetic modeling, but also helps to gain further insight into the combustion chemistry of biodiesel in future investigations. © The Royal Society of Chemistry 2015. Source

Gong B.,Wuhan Institute of Marine Electrical Propulsion | Cheng S.,Huazhong University of Science and Technology
Lecture Notes in Electrical Engineering

The neutral point (NP) voltage fluctuation is an innate problem for NPC three-level (3L) inverter. The NP voltage variation is analyzed, the relationship between NP voltage variation and NP current is studied, and a new control method is proposed in this paper. A closed-loop system is built by superimposing the voltage offset on the regulation phase in the proposed method. It is easy to balance the NP voltage by regulating the value of the voltage offset and the adjusting angle; the control structure is simple. Simulation results verify that the proposed control method has excellent ability to maintain the NP voltage balance. © Springer-Verlag Berlin Heidelberg 2016. Source

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