http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Model Predictive Control of Induction Motor Drives: Flux Control versus Torque Control
Yongchang Zhang,Haitao Yang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
Recently, model predictive torque control (MPTC) has been introduced as a powerful control method for induction motor (IM) drives. However, the weighting factor for stator flux must be tuned carefully to obtain satisfactory performance at different operation points. Unfortunately, so far the tuning of weighting factor in MPTC is mostly based on empirical procedure. This paper solves this problem by proposing a model predictive flux control (MPFC), which uses the stator flux vector as the control variable. As a result, the weighting factor in conventional MPTC is eliminated and the control complexity is significantly reduced. Both MPTC and MPFC are tested and compared in detail, including steady state performance, dynamic response and low speed operation. The experimental results prove that, the performance of conventional MPTC is dependent on the weighting factor and improper weighting factor would lead to significant performance deterioration. On the contrary, the proposed MPFC achieves similar or even better overall performance over a wide speed range with very low tuning work. Hence, it is concluded that the proposed MPFC is more practical than conventional MPTC.
Junpeng Yang,Qi Cai,Yongchang Liu,Chong Li,Zongqing Ma,Huijun Li 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4
The W-modifi ed Ti 2 AlNb-based alloys synthesized at 1100 °C by spark plasma sintering were solution treated at 1300 °Cfor 4 h and then aged at 800–1000 °C for 1 h. The phase composition, microstructure evolution, and microhardness of theaged alloys are investigated in this study. A signifi cant enhancement of hardness, ~ 750 HV, is obtained in the alloy aged at900 °C, while that of the one without W addition is only ~ 470 HV. The hardness is also higher than that of common β-Ti andTi–6Al–4V alloys. As the ageing temperature increases, the B2/O structure evolves from B2 + O colonies to Widmannstättenstructure, followed by a “disordering to ordering” procedure. This process also involves the variation of the angle betweenadjacent O phase from 90° to 60°. Specifi cally, a herringbone Widmannstätten B2 + O structure is constructed in the alloysaged in the α 2 + B2 + O phase region, which is related to the diff usion of W and the substitution of W for Nb in the latticeof B2 or O.
Daiwen Xiao,Yongchang Yang,Hua Liu,Hua Yu,Yingjun Yan,Wenfang Huang,Wei Jiang,Weijin Liao,Qi Hu,Bo Huang 한국미생물학회 2009 The journal of microbiology Vol.47 No.5
A method based on surface enhanced laser desorption and ionization time of flight mass spectrometry (SELDI-TOF MS) was developed for the rapid identification of Klebsiella pneumoniae by directly applying bacterial colonies without further protein extraction. A total of 40 K. pneumoniae and 114 other related microorganisms isolated clinically were analyzed by SELDI-TOF MS. An identification model for K. pneumoniae was established by artificial neural networks (ANNs) with classification accuracy of 100%. The model was blindly tested with 43 K. pneumoniae and 53 control bacteria again. The results showed that the model was successful with accuracy of 96.9%, sensitivity of 100% and specificity of 94.3%. This strategy is potential for rapid identification of K. pneumoniae.
Lei Shi,Zesheng Yan,Yongchang Liu,Xu Yang,Zhixia Qiao,Baoqun Ning,Huijun Li 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.1
The development of banded structure in HSLA steel during continuous cooling has been systematicallystudied using dilatometry and microstructural observations. At low cooling rates (<10 °C/min), the micro-structure contains alternating bands of ferrite and a mixture of pearlite and bainite. At higher cooling rate(>10 °C/min), the formation of pearlite is suppressed, and the corresponding microstructure consists ofbanded ferrite and bainite. Dilatometric analysis indicates that as ferrite and pearlite transformation at lowrates (or ferrite transformation at higher rates) completes, Manganese (Mn) and Carbon (C) concentrationin austenite can retard the bainitic transformation and result in the transformation stagnancy phenomenon. The magnitude of retardation and the bainite morphology are affected by Mn and C concentration. Theincreased cooling rate decreases Mn and C content in bainite, and then the length of the stagnant stagedecreases and bainite morphology changes from lower bainite to acicular ferrite.