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Liu, Huai-Cong,Lee, Ju Institute of Electrical and Electronics Engineers 2018 IEEE transactions on industrial electronics Vol.65 No.4
<P>As a kind of direct-on-line motor, super premium efficiency (IE4) line-start synchronous reluctance motors (LS-SynRMs) were developed recently and are now used in many applications, including fans, pumps, and compressors. This paper presents an optimum design and comparative study of LS-SynRMs with additional losses and impact during the manufacturing process (electrical steel cutting/punching damage as well as squirrel-cage die-casting with bubble effects). The work results indicate that the LS-SynRM design with the “manufacturing process loss” effect should be considered and compensated for the design in order to achieve an IE4 class efficiency and ensure synchronization. Furthermore, the LS-SynRM rotor with multilayer flux barriers and rotor slots is investigated in detail. The influences of optimum design geometrical parameters (flux barriers thickness, segments thickness, length of rotor slots, etc.) on the performances of the basic model and optimum design model are evaluated with finite-element analysis (FEA) results. For more accurate results, the effects of saturation, saliency ratio, inductance difference, and the change in the B-H/B-P curve in damaged motor core edges are considered. Meanwhile, in the squirrel cage, the porosity rate distributions are considered. The copper loss, iron loss, starting torque, power factor, efficiency, and synchronization ability are investigated. The experimental results verify the accuracy of the process presented in this paper.</P>
Liu, Huai-Cong,Cho, Sooyoung,Hong, Hyun-Seok,Lee, Ju,Lee, Ho-Joon IEEE 2017 IEEE transactions on magnetics Vol.53 No.11
<P>This paper proposes the design and analysis of a double-layer magnetic circuit structure for a high-force density hybrid fuel injector. In general, fuel injector models have disadvantages such as a significant leakage flux and magnetic saturation; therefore, a finite-element method is used to detail the model design and reduce the leakage flux from the electromagnet pole to the lead pipe. This change can help improve the fuel injector performance. In addition, a permanent magnet (PM) is inserted to increase the force density. Moreover, the no-load performance and demagnetization characteristic of the injector are analyzed according to the injector's working environment. The optimized hybrid fuel injector model with a PM shows substantially improved performance compared to a conventional design.</P>
Liu Liu,Yan-hua Fan,Lan-zhi Wu,Huai-min Zhang,Li-rong Yang 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.12
Two 3D isomorphous and isostructural complexes, namely, [Zn(BDOA)(bpy)(H2O)2]n (1) and [Cd(BDOA)- (bpy)(H2O)2]n (2); (BDOA = Benzene-1,4-dioxyacetic acid, bpy = 4,4'-bipyridine) were synthesized under hydrothermal conditions and characterized by means of elemental analyses, thermogravimetric (TG), infrared spectrometry, and single crystal X-ray diffraction. Complexes 1 and 2 crystallize in the triclinic system, space group P-1 and each metal ion in the complexes are six-coordinated with the same coordination environment. In the as-synthesized complexes, BDOA2− anions link central metal ions to form a 1D zigzag chain [-BDOA2− -Zn(Cd)-BDOA2−-Zn(Cd)-]∞, whereas bpy pillars connect metal ions to generate a 1D linear chain [-bpy- Zn(Cd)-bpy-Zn(Cd)-]∞. Both infinite chains are interweaved into 2D grid-like layers which are further constructed into a 3D open framework, where hydrogen bonds play as the bridges between the adjacent 2D layers. Luminescent properties of complex 1 showed selectivity for Hg2+ ion.
Liu, Huai-Cong,Cho, Sooyoung,Hong, Hyun-Seok,Joo, Kyoung-Jin,Ham, Sang-Hwan,Lee, Ju The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.6
This study focuses on the effects of using open stator slots in an interior permanent magnet traction motor with a magnetic slot wedge design in order to increase the power density at its base speed. In addition, such a configuration reduces the torque ripple under field-weakening conditions. Five different wedge models were selected, each of which was evaluated using a finite element analysis (FEA). Based on the initial model, we designed magnetic slot wedges for maximum back-EMF and minimum cogging torque. In addition, the d-q axis inductance was slightly altered due to the magnetic slot wedges. Finally, we analyzed the performance of a traction machine under field weakening control. Moreover, we have outlined the requirements for an ideal magnetic slot wedge design.
Optimal Slot Design of IPMSM in Railway With Independently Rotating Wheelsets
Liu, Huai-Cong,Lee, Ho-Joon,Seol, Hyun-Soo,Cho, Sooyoung,Lee, Ju,Oh, Ye Jun IEEE 2019 IEEE transactions on magnetics Vol.55 No.2
<P>This paper proposes a quasi-semi-closed (QSC) slot design method for an open-slot-type interior permanent magnet synchronous motor (IPMSM) for independently rotating wheelsets necessary to reduce the total harmonic distortion of no-load back-electromotive force and the torque ripple in the IPMSM. Four different slot-opening models were selected—the basic model, hairpin coil model, magnetic-wedge model, and QSC-slot model—and 2-D finite-element analysis was performed under open-circuit and load operations for each of the four models. Next, the relationships among the cogging torque, the torque ripple, and the saturation phenomenon in the core were analyzed. In addition, the manufacturing process, manufacturing cost, fill factor, end-winding resistance, copper loss, and efficiency were investigated. The experimental results verify the accuracy of the proposed method.</P>
Huai-Cong Liu,Sooyoung Cho,Hyun-Seok Hong,Kyoung-Jin Joo,Sang-Hwan Ham,Ju Lee 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.6
This study focuses on the effects of using open stator slots in an interior permanent magnet traction motor with a magnetic slot wedge design in order to increase the power density at its base speed. In addition, such a configuration reduces the torque ripple under field-weakening conditions. Five different wedge models were selected, each of which was evaluated using a finite element analysis (FEA). Based on the initial model, we designed magnetic slot wedges for maximum back-EMF and minimum cogging torque. In addition, the d-q axis inductance was slightly altered due to the magnetic slot wedges. Finally, we analyzed the performance of a traction machine under field weakening control. Moreover, we have outlined the requirements for an ideal magnetic slot wedge design.
Huai Liu,Xuejuan Cao,Ting Wang,Junnan Wei,Xing Tang,Xianhai Zeng,Yong Sun,Tingzhou Lei,Shijie Liu,Lu Lin 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.77 No.-
The conversion of concentrated 5-hydroxymethylfurfural (HMF) or fructose to 2,5-furandicarboxylic acid(FDCA), a renewable alternative to petroleum-derived terephthalate acid, is highly desirable butchallenging for FDCA production in an industrial scale. In this contribution, DMSO/H2O mixture wasdemonstrated as an effective medium for the production of FDCA from high concentration of HMF orfructose. For example, FDCA yield up to 93% was achieved at 10 wt% HMF concentration in DMSO/H2Oover commercially available Ru/C (2 equiv. NaHCO3, 130 C, 4 MPa O2 and 12 h). Furthermore, an overallFDCA yield of 65% was achieved from concentrated fructose (19 wt%) through a facile two-step process. Notably, it is so far the highest HMF or fructose concentration employed for FDCA formation. As comparedto pure water or DMSO, DMSO/H2O mixed system is able to stabilize HMF in an alkaline environment,which allows the efficient oxidation of HMF at high concentrations.
Liu, Huai-Cong,Kim, In-Gun,Oh, Ye Jun,Lee, Ju,Go, Sung-Chul IEEE 2017 IEEE transactions on magnetics Vol.53 No.6
<P>This paper proposes the optimization of the shape and size of a ferrite magnet and the arrangements necessary to reduce torque ripple and maximize back electromotive force (B-EMF) in a permanent-magnet-assisted synchronous reluctance motor. First, four different models of general magnet arrangements were selected, and analysis using the finite-element method was performed under open circuit and load operations for each of the four models. Next, the relationship between the cogging torque and the torque ripple was analyzed, considering the segment saturation phenomenon. Then, based on the initial model, the design was optimized for maximum B-EMF and minimum torque ripple, and the total harmonic distortion was measured. Finally, the validity and superiority of the optimized design were confirmed by manufacturing a prototype motor and performing the experiment.</P>
Liu, Liu,Fan, Yan-Hua,Wu, Lan-Zhi,Zhang, Huai-Min,Yang, Li-Rong Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.12
Two 3D isomorphous and isostructural complexes, namely, $[Zn(BDOA)(bpy)(H_2O)_2]_n$ (1) and $[Cd(BDOA)-(bpy)(H_2O)_2]_n$ (2); (BDOA = Benzene-1,4-dioxyacetic acid, bpy = 4,4'-bipyridine) were synthesized under hydrothermal conditions and characterized by means of elemental analyses, thermogravimetric (TG), infrared spectrometry, and single crystal X-ray diffraction. Complexes 1 and 2 crystallize in the triclinic system, space group P-1 and each metal ion in the complexes are six-coordinated with the same coordination environment. In the as-synthesized complexes, $BDOA^{2-}$ anions link central metal ions to form a 1D zigzag chain $[-BDOA^{2-}-Zn(Cd)-BDOA^{2-}-Zn(Cd)-]_{\infty}$, whereas bpy pillars connect metal ions to generate a 1D linear chain $[-bpy-Zn(Cd)-bpy-Zn(Cd)-]_{\infty}$. Both infinite chains are interweaved into 2D grid-like layers which are further constructed into a 3D open framework, where hydrogen bonds play as the bridges between the adjacent 2D layers. Luminescent properties of complex 1 showed selectivity for $Hg^{2+}$ ion.