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Subsection Synchronous Current Harmonic Minimum Pulse Width Modulation for ANPC-5L Inverter
Jiuyi Feng,Wenxiang Song,Yuan Xu,Fei Wang 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.5
Medium voltage drive systems driven by high-power multi-level inverters operating at low switching frequency can reduce the switching losses of the power device and increase the output power. Employing subsection synchronous current harmonic minimum pulse width modulation (CHMPWM) technique can maintain the total harmonic distortion of current at a very low level. It can also reduce the losses of the system, improve the system control performance and increase the efficiency of DC-link voltage accordingly. This paper proposes a subsection synchronous CHMPWM approach of active neutral point clamped five-level (ANPC-5L) inverter under low switching frequency operation. The subsection synchronous scheme is obtained by theoretical calculation based on the allowed maximum switching frequency. The genetic algorithm (GA) is adopted to get the highprecision initial values. So the expected switching angles can be achieved with the help of sequential quadratic programming (SQP) algorithm. The selection principle of multiple sets of the switching angles is also presented. Finally, the validity of the theoretical analysis and the superiority of the CHMPWM are verified through both the simulation results and experimental results.
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Subsection Synchronous Current Harmonic Minimum Pulse Width Modulation for ANPC-5L Inverter
Feng, Jiuyi,Song, Wenxiang,Xu, Yuan,Wang, Fei The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5
Medium voltage drive systems driven by high-power multi-level inverters operating at low switching frequency can reduce the switching losses of the power device and increase the output power. Employing subsection synchronous current harmonic minimum pulse width modulation (CHMPWM) technique can maintain the total harmonic distortion of current at a very low level. It can also reduce the losses of the system, improve the system control performance and increase the efficiency of DC-link voltage accordingly. This paper proposes a subsection synchronous CHMPWM approach of active neutral point clamped five-level (ANPC-5L) inverter under low switching frequency operation. The subsection synchronous scheme is obtained by theoretical calculation based on the allowed maximum switching frequency. The genetic algorithm (GA) is adopted to get the high-precision initial values. So the expected switching angles can be achieved with the help of sequential quadratic programming (SQP) algorithm. The selection principle of multiple sets of the switching angles is also presented. Finally, the validity of the theoretical analysis and the superiority of the CHMPWM are verified through both the simulation results and experimental results.
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Xiaocan Yu,Chenglin Liu,Chunlian Wang,Jiuyi Wang,Haiming Xu,Haonan Li 한국지질과학협의회 2018 Geosciences Journal Vol.22 No.3
The Paleocene sedimentary sequence in the Jiangling Depression was deposited in a salt lake environment. Based on detailed core observation of four drillholes in the Jiangling Depression, a study of sedimentary characteristics of glauberite in Paleocene lacustrine deposits was conducted through thin section petrography, X-ray diffraction, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). This study has revealed five types of geological occurrences and six types of profile distribution features of glauberite. On the basis of petrological and mineralogical characteristics, we propose that the glauberite is mainly formed by crystallization from saturated sulfate solution and by ion exchange between sulfate solution and calcium-bearing pore solution. Glauberite mainly occurs in the late stage of Paleocene, when brine is relatively highly concentrated. Replacement of gypsum by glauberite is subordinate. The depositional model of glauberite is also discussed. The sulphur isotopic values δ34S) and the strontium ratios (87Sr/86Sr) of the sulphate suggest a non-marine brine supply. The profile distribution features of glauberite contribute to a better understanding of the past climate change. The glauberite in Late Paleocene is frequently interbedded with dolomite, anhydrite, halite or thenardite, suggesting fluctuation of lake water salinity and climate. Trace element compositions of the mudstones imply the reducing condition and fluctuating salinity. The Homogenization temperatures and hydrogen and oxygen isotopic values (δDSMOW and δ18OSMOW) in halite and thenardite inclusions further indicate that in Paleocene the temperature was relatively high and fluctuant. Moreover, the palaeoclimate was drier in the late stage of Late Paleocene, though the temperature was cooler/lower.
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