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Qiu, Hongbo,Yu, Wenfei,Tang, Bingxia,Yang, Cunxiang,Zhao, Haiyang The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.8 No.1
When the inter-turn short circuit (ITSC) fault occurs, the distortion of the magnetic field is serious. The motor loss variations of each part are obvious, and the motor temperature field is also affected. In order to obtain the influence of the ITSC fault on the motor temperature distribution, firstly, the normal and the fault finite element models of the permanent magnet synchronous motor (PMSM) were established. The magnetic density distribution and the eddy current density distribution were analyzed, and the mechanism of loss change was revealed. The effects of different forms and degrees of the fault on the loss were obtained. Based on the loss analysis, the motor temperature field calculation model was established, and the motor temperature change considering the loop current was analyzed. The influence of the fault on the motor temperature distribution was revealed. The sensitivity factors that limit the motor continuous operation were obtained. Finally, the correctness of the simulation was verified by experiments. The conclusions obtained are of great significance for the fault and high temperature demagnetization of the permanent magnet analysis.
Hongbo Qiu,Wenfei Yu,Bingxia Tang,Cunxiang Yang,Haiyang Zhao 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.4
When the inter-turn short circuit (ITSC) fault occurs, the distortion of the magnetic field is serious. The motor loss variations of each part are obvious, and the motor temperature field is also affected. In order to obtain the influence of the ITSC fault on the motor temperature distribution, firstly, the normal and the fault finite element models of the permanent magnet synchronous motor (PMSM) were established. The magnetic density distribution and the eddy current density distribution were analyzed, and the mechanism of loss change was revealed. The effects of different forms and degrees of the fault on the loss were obtained. Based on the loss analysis, the motor temperature field calculation model was established, and the motor temperature change considering the loop current was analyzed. The influence of the fault on the motor temperature distribution was revealed. The sensitivity factors that limit the motor continuous operation were obtained. Finally, the correctness of the simulation was verified by experiments. The conclusions obtained are of great significance for the fault and high temperature demagnetization of the permanent magnet analysis.
Hongbo Qiu,Yuedong Guo,Wenfei Yu,Bingxia Tang,Cunxiang Yang 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.3
With the development of electric electron technology and controlling technology, controller for driving permanent magnet synchronous motors is used widely. The using of a controller can expand the motor speed range and improve motor runtime performances. However, the output current of a controller contains lots of time harmonics that will have bad infl uences on motor torque and losses. In order to analyze the infl uences of the time harmonics on the motor performances, diff erent time harmonic currents were injected into the motor armature. Taking a 750 W, 250 r/min permanent magnet synchronous motor with hybrid magnet poles (HPPMSM) as an example, the 2-D fi nite model was established. On this basis, the torque ripple and eddy current losses of permanent magnets with diff erent time harmonics were obtained. The infl uences of time harmonics on motor torque ripple and eddy current losses were determined, and the impacting mechanism was revealed. The analyses may be helpful for the optimal design of HPPMSM.
Zhao, Guoqing,Shen, Wenfei,Jeong, Eunwook,Lee, Sang-Geul,Yu, Seung Min,Bae, Tae-Sung,Lee, Gun-Hwan,Han, Seung Zeon,Tang, Jianguo,Choi, Eun-Ae,Yun, Jungheum American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.32
<P>Improving the wetting ability of Ag on chemically heterogeneous oxides is technically important to fabricate ultrathin, continuous films that would facilitate the minimization of optical and electrical losses to develop qualified transparent Ag film electrodes in the state-of-the-art optoelectronic devices. This goal has yet to be attained, however, because conventional techniques to improve wetting of Ag based on heterogeneous metallic wetting layers are restricted by serious optical losses from wetting layers. Herein, we report on a simple and effective technique based on the partial oxidation of Ag nanoclusters in the early stages of Ag growth. This promotes the rapid evolution of the subsequently deposited pure Ag into a completely continuous layer on the ZnO substrate, as verified by experimental and numerical evidence. The improvement in the Ag wetting ability allows the development of a highly transparent, ultrathin (6 nm) Ag continuous film, exhibiting an average optical transmittance of 94% in the spectral range 400-800 nm and a sheet resistance of 12.5 Ω sq<SUP>-1</SUP>, which would be well-suited for application to an efficient front window electrode for flexible solar cell devices fabricated on polymer substrates.</P> [FIG OMISSION]</BR>
Limin Hou,Chaoyue Qiao,Qingbo Yu,Wenfei Wu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.3
The technology of chemical looping air separation, with the characteristics of simple operation, low cost, and low energy consumption, separates oxygen from air with the oxygen carrier. In this work, reaction properties of monolithic oxygen carriers were investigated in a fixed-bed apparatus, with the consideration of the reactor temperature, oxygen concentration, and reaction gas flow. The XRD results showed that active phase, Al2O3, and cordierite cannot react with each other in calcination processing. The SEM results showed that the micromorphology of oxygen carrier was loaded on cordierite honeycomb uniformly with sphere or sphere-like particles. Oxygen carriers show a faster oxygen release rate and a slower oxygen intake rate. With increasing of absorption temperature, oxygen concentration of inlet gas, and desorption temperature, the reaction rate per unit mass increases. With increasing of gas flow rate, the reaction rate per unit mass decreases. The maximum value of the reaction rate per unit mass was obtained by Y0.95Ti0.05BaCo4O7+δ monolith sample. Samples substituted with Dy element showed fine performance of stability, as Dy substitution causes more serious local lattice distortions.