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- 저자 : Jiayi Fu (검색결과 3 건)
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Deng Weitao,Fu Xin,Tang Jiayi,Zhang Xiuyun,Cheng Wangbin 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3
The rotation vector of the matrix converter has the characteristic that the common mode voltage is zero, so the direct torque control (DTC) strategy using the rotation vector can effectively suppress the common mode voltage of the motor system. However, because the direction of the rotation vector is constantly changing and the distribution is extremely uneven, the existing DTC based on the rotation vector not only has a complicated switching table, but also increases the torque ripple and current harmonics. In this paper, a novel direct torque control strategy using virtual rotation vectors is proposed. The virtual rotation vector is synthesized by the rotation vector with identical rotating direction, and the duty cycle of the selected rotation vector is theoretically derived and calculated, leading to six evenly distributed virtual rotation vectors with fixed relative positions, and therefore a simple-form switching table can be easily constructed. The proposed control strategy is experimentally verified, and the results show that, compared with the traditional rotation vector-based DTC, the proposed strategy not only achieves zero common-mode voltage, but also significantly reduces torque ripple and current harmonics, improving the steady-state performance of the motor system.
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Impact of Various Charge States of Hydrogen on Passivation of Dislocation in Silicon
Lihui Song,Jingjing Lou,Jiayi Fu,Zhenguo Ji 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.5
Dislocation, one of typical crystallographic defects in silicon, is detrimental to the minority carrier lifetime of silicon wafer. Hydrogen passivation is able to reduce the recombination activity of dislocation, however, the passivation efficacy is stronglydependent on the experimental conditions. In this paper, a model based on the theory of hydrogen charge state control isproposed to explain the passivation efficacy of dislocation correlated to the peak temperature of thermal annealing and illuminationintensity. Experimental results support the prediction of the model that a mix of positively charged hydrogen andnegatively charged hydrogen at certain ratio can maximise the passivation efficacy of dislocation, leading to a better powerconversion efficiency of silicon solar cell with dislocation in it.
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Experimental Studies on Bond Performance of BFRP Bars Reinforced Coral Aggregate Concrete
Lei Wang,Zhaoping Song,Jin Yi,Jiayi Li,Feng Fu,Kai Qian 한국콘크리트학회 2019 International Journal of Concrete Structures and M Vol.13 No.7
Basalt fiber reinforced polymer (BFRP) rebars reinforced coral aggregate concrete is a new type of concrete used in ocean engineering. In order to investigate the bond performance between BFRP rebars and coral concrete, 30 pullout tests were carried out in 10 groups with different diameters of BFRP rebars, bonding lengths and strength of the coral concrete. The results show that good bonding between BFRP rebars and coral concrete were achieved. The main failure modes can be categorized as BFRP rebars pull out destruction, splitting failure of coral concrete and BFRP rebars fracture. The bond slip ( τ -s ) curves of the BFRP rebars and coral concrete were obtained during the tests. It was found to be similar to the common concrete using fiber reinforced polymer (FRP) bars. The bond-slip relation can be roughly divided into micro-slip phase, slip phase, decline phase, and the residual stress stage. The bond between BFRP rebars and coral concrete increases with the increase of the bond length and diameter of BFRP rebars, but the average bond stress will decrease. Moreover, increasing the strength of coral concrete is effective to improve the bond performance of BFRP rebars. In this paper, the continuous bond slip model (Gao et al. in J Zhengzhou Univ 23:1.5, 2002) was used to represent the τ -s constitutive relationship of BFRP rebars and coral concrete. The analysis show that the proposed model has a high degree of accuracy in representing τ -s curve of BFRP rebars and coral concrete.
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