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RISS 인기검색어
- 검색키워드
- 저자 : Liu Yalu (검색결과 3 건)
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Yalu Mu,Jilong Liu,Zhiqin Mai,Xiao Fei,Kangzhuang Fu 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.5
In the permanent magnet synchronous motor (PMSM) high-frequency (HF) rotating voltage injection method, a current demodulation process is usually used to improve the rotor position estimation accuracy. Current demodulation is usually realized by the synchronous frame high-pass filter (SFHF) algorithm. However, the current demodulation process is complicated, and the position estimation error changes with the rotation speed. To this end, an improved HF rotating voltage injection method based on the direct decoupling (DD) current demodulation algorithm is proposed. This method takes into account the comprehensive matching optimization of both the position error cancelation compensation and the current demodulation simplification. In addition, it completely solves the problems of insufficient position estimation accuracy and complex algorithm implementation. Finally, a three-phase PMSM is taken as the research object to verify the effectiveness of the proposed method.
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Mu Yalu,Liu Jilong,Mai Zhiqin,Xiao Fei,Li Shun 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.4
In a permanent magnet synchronous motor (PMSM) drive system without voltage sensor, aff ected by the inverter non-linearities, there is a phase off set problem between the reconstructed voltage and the actual voltage. This phase off set increases as the switching frequency decreases, especially pronounced in subway permanent magnet traction systems operating at the hundreds of Hertz level. As a result, in the medium-to high-speed range, the estimated rotor position progressively advances ahead of the actual rotor position, accompanied by an increasing content of estimated speed harmonics. To address this issue, this paper proposes a sensorless control performance optimization strategy for low switching frequency permanent magnet drive systems. On the one hand, the position error compensation strategy of voltage phase advance adjustment is adopted to eliminate the phase off set between the actual voltage and the reconstructed voltage. On the other hand, the method of cascading the adaptive notch fi lter with the low-pass fi lter is used to eliminate the harmonic interference in the feedback current, so as to realize the harmonic suppression of the estimated speed. The experimental results have confi rmed the eff ectiveness of the proposed optimization strategy, ultimately the position sensorless control of the PMSM drive system with the inverter switching frequency of 500 Hz was achieved, eff ectively optimizing the control performance at low switching frequencies.
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Huang Kailang,Chen Hongwei,Liu Yalu,Hong Qihua,Yang Bin,Wang Jiakun 아세아·태평양축산학회 2022 Animal Bioscience Vol.35 No.9
Objective: This study identified the major lactic acid bacteria (LAB) strains from different fermented total mixed rations (FTMRs) via metataxonomic analysis and evaluated the ability of their standard strain as ensiling inoculants for corn stover silage. Methods: The bacterial composition of eight FTMRs were analyzed by 16S rDNA sequencing. Corn stover was ensiled without LAB inoculation (control) or with 1×106 cfu/g LAB standard strain (Lactobacillus vaginalis, Lactobacillus reuteri, Lactobacillus helveticus, or Lactobacillus paralimentarius) selected from the FTMRs or 10 g/t commercial silage inoculant (CSI) around 25°C for 56 days. For each inoculation, a portion of the silage was sampled to analyze ensiling characteristics at time intervals of 0, 1, 3, 7, 14, 28, and 56 days, gas production (GP), microbial crude protein and volatile fatty acids as the measurements of rumen fermentation characteristics were evaluated in vitro with the silages of 56 days after 72 h incubation. Results: Lactobacillus covered >85% relative abundance of all FTMRs, in which L. pontis, L. vaginalis, L. reuteri, L. helveticus, and L. paralimentarius showed >4% in specific FTMRs. CSI, L. helveticus, and L. paralimentarius accelerated the decline of silage pH. Silage inoculated with L. paralimentarius and CSI produced more lactic acid the early 14 days. Silage inoculated with L. paralimentarius produced less acetic acid and butyric acid. For the in vitro rumen fermentation, silage inoculated with CSI produced more potential GP, isobutyric acid, and isovaleric acid; silage inoculated with L. helveticus produced more potential GP and isovaleric acid, silage inoculated with L. paralimentarius or L. reuteri produced more potential GP only. Conclusion: The standard strain L. paralimentarius (DSM 13238) is a promising ensiling inoculant for corn stover silage. The findings provide clues on strategies to select LAB to improve the quality of silage. Objective: This study identified the major lactic acid bacteria (LAB) strains from different fermented total mixed rations (FTMRs) via metataxonomic analysis and evaluated the ability of their standard strain as ensiling inoculants for corn stover silage.Methods: The bacterial composition of eight FTMRs were analyzed by 16S rDNA sequencing. Corn stover was ensiled without LAB inoculation (control) or with 1×106 cfu/g LAB standard strain (Lactobacillus vaginalis, Lactobacillus reuteri, Lactobacillus helveticus, or Lactobacillus paralimentarius) selected from the FTMRs or 10 g/t commercial silage inoculant (CSI) around 25°C for 56 days. For each inoculation, a portion of the silage was sampled to analyze ensiling characteristics at time intervals of 0, 1, 3, 7, 14, 28, and 56 days, gas production (GP), microbial crude protein and volatile fatty acids as the measurements of rumen fermentation characteristics were evaluated in vitro with the silages of 56 days after 72 h incubation.Results: Lactobacillus covered >85% relative abundance of all FTMRs, in which L. pontis, L. vaginalis, L. reuteri, L. helveticus, and L. paralimentarius showed >4% in specific FTMRs. CSI, L. helveticus, and L. paralimentarius accelerated the decline of silage pH. Silage inoculated with L. paralimentarius and CSI produced more lactic acid the early 14 days. Silage inoculated with L. paralimentarius produced less acetic acid and butyric acid. For the in vitro rumen fermentation, silage inoculated with CSI produced more potential GP, isobutyric acid, and isovaleric acid; silage inoculated with L. helveticus produced more potential GP and isovaleric acid, silage inoculated with L. paralimentarius or L. reuteri produced more potential GP only.Conclusion: The standard strain L. paralimentarius (DSM 13238) is a promising ensiling inoculant for corn stover silage. The findings provide clues on strategies to select LAB to improve the quality of silage.
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