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Development of a Current-Sensorless Multi-Loop Control for Standalone PWM Inverters
Yuan Yisheng,Liuchen Chang,Song Pinggang 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
A current-sensorless multi-loop control method that estimates the capacitor current is proposed for standalone inverter applications. The theory of the control loop is given, and a mathematical model is analyzed. The effect of capacitor parameter mismatch on system characteristics was emphasized and discussed through modeling and simulation. Finally, experimental results comparing the characteristics of the output voltage under parameter mismatch conditions verified the operation and merits of the proposed controller.
Novel L‑R modulation resonant converter with wide output range and low output voltage ripple
Yisheng Yuan,Chenyu Yi,Neng Peng 전력전자학회 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.12
The disadvantage of resonant converter with pulse frequency modulation in applications with wide voltage gain is that the frequency modulation range is wide, which causes difficulty in optimizing the design of transformer and increases thehigh-frequency switching loss. In the light load condition, the resonant converter with pulse width modulation has a large circulating current loss. In this paper, a soft-switching converter with linear-resonant composite modulation is proposed. It has two operation modes and can adjust the voltage gain in a wide range with narrow frequency variation range. In the fixed frequency mode, no circulating current is present in the full load range, and the light load efficiency is improved. In variable frequency mode, the feedback loop of the converter is simple, which reduces the loss in the feedback loop. The operation principle and voltage gain characteristics of the two modes are analyzed in detail, and the parameter design steps are given. An experimental prototype based on constant current and constant voltage charging is built to demonstrate its feasibility.
Yuan Gao,Jianjun Zhang,Li Li,Feng Su,Zhenhua Gong,Yisheng Lai,Yihua Zhang 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.7
ZCVI4-2 was a novel nitric oxide-releasing glycosyl derivative of oleanolic acid that displayed strong cytotoxicity selectively against human hepatocellular carcinoma in vitro and in vivo. In this study, ZCVI4-2 was characterized by FT-IR spectroscopy, differential scanning calorimetry,powder X-ray diffractometry, Raman spectroscopy, hygroscopicity and stability. A high performance liquid chromatography method was also established for the quantitative determination of solubility and additional stability profile of ZCVI4-2. ZCVI4-2 was found to be an amorphous and stable solid with low solubility of less than 10 μg/mL. Based on the solubilization tests that included methods of cosolvency and micellization, the solution mixture of 5% Solutol HS-15, 5% 1, 2-propylene glycol and 5% anhydrous ethanol was determined to be the system for the preparation of the ZCVI4-2 early injection solution. The effect of pH, temperature, light and injectable isotonic glucose or NaCl solution on ZCVI4-2 injection was also investigated. Good stability was observed at all testing conditions. Under the conditions studied, the NO-releasing rate and amount of ZCVI4-2 from the early injection solution in rat plasma demonstrated a promising therapeutic efficacy while maintaining a good safety profile.
Pu Yuan,Yisheng Zhu,Dehai Li,Xuefeng Lu 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.5
Freeze-thaw cycle and moisture content are important factors for structural strength degradation in cold areas. Using coal gangue and slag to prepare alkali slag ceramsite concrete (ASCC) can implement the reuse of solid waste of coal gangue and slag. To study the influence of ceramsite content and moisture content on compressive strength and energy characteristics under freeze-thaw cycles (FTCs), uniaxial compression tests were conducted for ASCC with different moisture contents (dry, 4%, 5%, and 6%) and ceramsite contents (0%, 25%, 50%, 75%, and 100%) after 20 FTCs. The results show that the stress-strain curves of ASCC with different moisture contents and ceramsite contents all undergo four stages under FTCs, namely initial compaction, elastic deformation, crack development, and post-peak failure. The addition of coal gangue ceramsite makes concrete failure show certain ductility characteristics. Both compressive strength and ultrasonic pulse velocity decrease with the moisture content, and elastic energy utilization rate of wet ASCC is better than that of dry ASCC. The compressive strength, ultrasonic pulse velocity, and energy characteristics all decrease with the increase of ceramsite content.
Hybrid phase-shifted modulation method for hybrid cascaded H-bridge inverters
Hu, Wenhua,Guo, Jiamin,Liu, Jianfeng,Yuan, Yisheng The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.10
Due to its unreasonable DC voltage distribution, the phase-shifted pulse width modulation (PS-PWM) method cannot be directly applied to equal-ratio and equal-difference hybrid CHB inverters. Thus, these types of inverters lose the double-frequency characteristic of the CHB topology. To preserve this double-frequency characteristic, reduce the switching frequency of the high-voltage cells, and simplify the modulation method. This article proposes an optimized topology for the hybrid CHB inverter by optimizing the distribution of the DC voltage. A hybrid PS-PWM method is also proposed by combing the step-wave modulation method and the PS-PWM method. Theoretical analysis, simulation analysis, and experimental results show that the optimized topology and the hybrid PS-PWM method are both valid and feasible.