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Peiji Zhu,Meiqin Mao,Shuang Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
In traditional single phase converters for EV chargers used in private cars, the power flow is only unidirectional, and the bulky and short-lifetime electrolytic capacitors are usually used to issue the second-order ripple power between the AC and DC side. To address the problem, this paper proposes a control strategy to enable the single phase EV charger to achieve both four-quadrant operation and power decoupling control at the same time so that the EVs can respond dispatching commands from the future smart grid as distributed energy resources, meanwhile the size of the charger can be reduced. This control method is based on our previous work, proposed novel topology of single phase converter using a small film capacitor to decouple the second-order power. The operation principle of the proposed control strategy is analyzed in detail, and the design method of decoupling capacitance for both power decoupling and reactive power control purposes is provided. Simulation results by MATLAB/Simulink are provided to verify the effectiveness of the proposed control strategy.
Zhu Youshuang,Zhang Haibo,Cao Mingle,Wei Zhenzhen,Huang Feng,Gao Peiji 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.5
Production of laccase using a submerged culture of Trametes versicolor sdu-4 was optimized using a central composite design of the Response Surface Methodology. Optimized conditions gave a laccase yield of 4,213 U/L which was approximately three times of that in basal medium. The laccase was purified to homogeneity using a three-step process. The overall yield of the purification was 58%, with a purification fold of 11.4 and a specific activity of 1320.7 U/mg protein. The molecular mass of the laccase was 60 kDa. The optimum pH values of the enzyme were 2.2, 3.7, and 7 for the oxidations of ABTS, DMP, and syringaldazine, respectively. The enzyme had adaptability to a broad pH range and high temperature and wsa stable at pH 3.0 ~ 10.0. The half-life of this laccase at 70°C was 2.2 h. Methyl red, 2-bromophenol, and 4-bromophenol were oxidized by the purified laccase in the absence of mediators. Purified laccase was effective in the decolorization of several dyes and was not inhibited by Cu^(2+), Mn^(2+), Zn^(2+), Na^+, K^+, Mg^(2+), Ba^(2+), and Ca^(2+) at 5 mM. These excellent characteristics made it a highly attractive candidate for industrial use.