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RISS 인기검색어
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- 저자 : Wenxi Yao (검색결과 4 건)
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Novel Five-Level Three-Phase Hybrid-Clamped Converter with Reduced Components
Bin Chen,Wenxi Yao,Zhengyu Lu 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
This study proposes a novel five-level three-phase hybrid-clamped converter composed of only six switches and one flying capacitor (FC) per phase. The capacitor-voltage-drift phenomenon of the converter under the classical sinusoidal pulse width modulation (SPWM) strategy is comprehensively analyzed. The average current, which flows into the FC, is a function of power factor and modulation index and does not remain at zero. Thus, a specific modulation strategy based on space vector modulation (SVM) is developed to balance the voltage of DC-link and FCs by injecting a common-mode voltage. This strategy applies the five-segment method to synthesize the voltage vector, such that switching losses are reduced while optional vector sequences are increased. The best vector sequence is then selected on the basis of the minimized cost function to suppress the divergence of the capacitor voltage. This study further proposes a startup method that charges the DC-link and FCs without any additional circuits. Simulation and experimental results verify the validity of the proposed converter, modulation strategy, and precharge method.
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Novel Five-Level Three-Phase Hybrid-Clamped Converter with Reduced Components
Chen, Bin,Yao, Wenxi,Lu, Zhengyu The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
This study proposes a novel five-level three-phase hybrid-clamped converter composed of only six switches and one flying capacitor (FC) per phase. The capacitor-voltage-drift phenomenon of the converter under the classical sinusoidal pulse width modulation (SPWM) strategy is comprehensively analyzed. The average current, which flows into the FC, is a function of power factor and modulation index and does not remain at zero. Thus, a specific modulation strategy based on space vector modulation (SVM) is developed to balance the voltage of DC-link and FCs by injecting a common-mode voltage. This strategy applies the five-segment method to synthesize the voltage vector, such that switching losses are reduced while optional vector sequences are increased. The best vector sequence is then selected on the basis of the minimized cost function to suppress the divergence of the capacitor voltage. This study further proposes a startup method that charges the DC-link and FCs without any additional circuits. Simulation and experimental results verify the validity of the proposed converter, modulation strategy, and precharge method.
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Zheyu Miao,Sun Long,Wenxi Yao,Zhengyu Lu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
LCL-filters are widely used in grid-tied converters for improved attenuations and lower costs. To prevent instability, the LCL resonance peak needs to be damped by the active dampers that avoid the dissipations but increase the control complexity. In the weak grid, the harmonic currents and the grid impedance variations make the control become more complicated and difficult. The influence of the harmonic currents and the grid impedance in parallel system is researched in this paper. Then, a selftuning notch filter (STNF) is introduced, and the resonance peak identification process implemented in digital controller is proposed in detailed. The consumption and tracking error of the STNF are analyzed guaranteeing an effective design. By adopting the STNF, the local maximum gain frequency is estimated online in response to the grid inductance variations. The construction as well as optimal design principles of the hybrid active damper are proposed in detail. To further reject the harmonic voltage effects, a PR regulator with a harmonic compensation controller is adopted. A step-by-step example design of the controller is illustrated in detail. The online implementation in DSP controllers and the digitization influence of the proposed method are also amply discussed. Finally, simulation and experimental results verify the effectiveness of the proposed method.
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Zhou Xuefei,Miao Wei,Cheng Wenxi,Lin Haowei,Lin Haowei,Zheng Hongjuan,Cheng Qiaohuan,Wang Renjie,Yao Chenxue,Liu Xiaobo 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.6
A series of poly(arylene ether nitrile) containing versatile carboxyl and sulfonic groups (CSPEN) were magnetically functionalized by ferroferric oxide (Fe3O4), and the obtained magnetic adsorbents (Fe3O4/CSPEN) were used to remove methylene blue (MB) dye from aqueous solution. The systematical characterizations that including scanning electron microscope (SEM), X-ray powder diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), Fourier transform infrared (FTIR) certified that the Fe3O4/CSPEN possessed versatile functional groups and magnetic separation properties. The batch adsorption studies revealed that the Fe3O4/CSPEN not only displayed high selective adsorption ability for cationic MB in the presence of anionic MO, but also exhibited a removal efficiency as high as 98.2%. Besides, the adsorption kinetics and isotherm matched well with pseudo-second-order model and Langmuir model, respectively, and the maximum adsorption capacity of Fe3O4/CSPEN for MB was 92.029 mg/g. The FTIR and Brunauer-Emmett-Teller (BET) analyses confirmed that the outstanding adsorption capacity of Fe3O4/CSPEN was attributed to their own microporous structure and the electrostatic interaction with MB. Therefore, the modified magnetic adsorbent can be used to selectively remove cationic dye from aqueous solution.
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