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RISS 인기검색어
- 검색키워드
- 저자 : Li Shenghai (검색결과 4 건)
- 무료
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- 유료
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Torque Ripple Minimization in Direct Torque Control of Brushless DC Motor
Li, Zhenguo,Zhang, Songfa,Zhou, Shenghai,Ahn, Jin-Woo The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.5
This paper mainly proposes a direct torque control strategy to minimize torque ripple in brushless DC (BLDC) motor. BLDC motor has large current and torque ripple when one voltage vector applied in one cycle due to its low inductance. Hence, this paper proposed a hysteresis torque control with PWM mode to control the resultant torque. Moreover, when the direct torque control system is operating during the two-phase half-bridge $120^{\circ}$ conduction mode, large torque ripple in commutation area appears every 120 electrical degree. Based on analyzing the root of torque ripple in detail, lookup tables of switching devices states for new half-bridge modulation mode in the positive and negative reference torque put forwarded. Finally, simulations by MATLAB software and experiment results from DSP are presented to verify the feasibility and effectiveness of the proposed strategy operating in four-quadrant operation.
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Torque Ripple Minimization in Direct Torque Control of Brushless DC Motor
Zhenguo Li,Songfa Zhang,Shenghai Zhou,Jin-Woo Ahn 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.5
This paper mainly proposes a direct torque control strategy to minimize torque ripple in brushless DC (BLDC) motor. BLDC motor has large current and torque ripple when one voltage vector applied in one cycle due to its low inductance. Hence, this paper proposed a hysteresis torque control with PWM mode to control the resultant torque. Moreover, when the direct torque control system is operating during the two-phase half-bridge 120° conduction mode, large torque ripple in commutation area appears every 120 electrical degree. Based on analyzing the root of torque ripple in detail, lookup tables of switching devices states for new half-bridge modulation mode in the positive and negative reference torque put forwarded. Finally, simulations by MATLAB software and experiment results from DSP are presented to verify the feasibility and effectiveness of the proposed strategy operating in four-quadrant operation.
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Piao, Zhonglie,Ma, Teng,Li, Jiawen,Wiedmann, Maximilian T.,Huang, Shenghai,Yu, Mingyue,Kirk Shung, K.,Zhou, Qifa,Kim, Chang-Seok,Chen, Zhongping American Institute of Physics 2015 Applied Physics Letters Vol.107 No.8
<P>Intravascular photoacoustic imaging at 1.7 mu m spectral band has shown promising capabilities for lipid-rich vulnerable atherosclerotic plaque detection. In this work, we report a high speed catheter-based integrated intravascular photoacoustic/intravascular ultrasound (IVPA/IVUS) imaging system with a 500 Hz optical parametric oscillator laser at 1725 nm. A lipid-mimicking phantom and atherosclerotic rabbit abdominal aorta were imaged at 1 frame per second, which is two orders of magnitude faster than previously reported in IVPA imaging with the same wavelength. Clear photoacoustic signals by the absorption of lipid rich deposition demonstrated the ability of the system for high speed vulnerable atherosclerotic plaques detection. (C) 2015 AIP Publishing LLC.</P>
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Guo Xiaofeng,Yang Kun,Yang Wei,Zhao Long,Li Shenghai,Ding Baohong 한국기상학회 2020 Asia-Pacific Journal of Atmospheric Sciences Vol.56 No.4
Using eddy-covariance turbulence measurements over a Tibetan glacier, we present a description of scalar turbulence characteristics in the stable boundary layer. Interesting behaviours are demonstrated in terms of temperature–humidity de-correlation and dissimilarity. That is, a lack of perfect correlation occurs between the two scalars (i.e., correlation coefficients <1 in magnitude); overall, sensible heat is more efficiently transported than water vapour over snow and ice surfaces. Such behaviours provide evidence of departures from the idealized expectation of Monin–Obukhov similarity theory—all scalars assume a perfect level of linear correlation and an equal efficiency level of vertical transport. Results presented herein are noteworthy in that observations over uniform glaciated surfaces involve negligible effects of either a canopy-induced roughness sublayer or heterogeneity in the temperature–humidity source/sink distributions. Moreover, we address two different approaches to representing the heat-to-moisture transport efficiency in stable conditions. A new approach is extended through application of the quadrant analysis technique, thereby representing it as a function of atmospheric stability. Caution is further advised in the use of this approach, when temperature–humidity turbulence becomes markedly de-correlated. A second approach, as previously applied for estimating forest evaporation fluxes in unstable conditions, is extended to a stable boundary layer over snow and ice surfaces.
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