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Zhankui Cui,Senlin Li,Junqiang Zhou,Jianli Zhang,Suxiang Ge,Zhi Zheng 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.2
Spherical Bi2S3 nanoparticles (NPs) were prepared by a facile in situ thermal sulfuration method. Different Bi2S3 samples were obtained by controlling the sulfuration time. The products were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), Raman and Fourier-transform infrared (FT-IR) methods. The optical properties were examined by UVvisible-near-infrared (UV-Vis–NIR) and photoluminescence (PL) techniques. The results show that the phase of the products after sulfuration is pure and the spherical shape of Bi NPs has been successfully transmitted to Bi2S3 samples. The light absorption edges exhibit red shift to 1060 nm while the light emission displays blue shift to 868 nm, compared with the energy bandgap of bulk Bi2S3. The reason for the special optical properties of Bi2S3 NPs by this in situ sulfuration route is considered to associate with the defects and quantum size effect of NPs.
Mengmeng Wu,Wenxiang Zhao,Jinghua Ji,Junqiang Zheng,Jianhua Luo 한국자기학회 2018 Journal of Magnetics Vol.23 No.2
Fractional-slot concentrated windings (FSCWs) are characterized with many advantages. However, their magnetic fields have rich space harmonics. These harmonics, especially tooth harmonics, have negative effect on machine performances. This paper proposes a new method to reduce the tooth harmonics in FSCW permanent-magnet (PM) machine, in which the magnetic distribution in air-gap will be affected by winding span radian. Also, a new stator structure is designed on the method. By using the new stator design, each order tooth harmonic can be reduced significantly and the working harmonic can also be increased slightly. Simultaneously, the unbalanced radial magnetic force can be significantly weakened. The basic principle of tooth harmonic reduction method can be analyzed by using the stator structure of the FSCW machine with single layer windings. Then, a three phase 18-slot/16-pole FSCW machine with double layer windings is newly designed, which can effectively weaken the tooth harmonic components of FSCW machines. It is shown that, under the fixed electrical and geometrical constrains, the designed FSCW machine has better performances, such as loss, vibration and noise, than the conventional ones.
Shengdao Zhu,Jinghua Ji,Wenxiang Zhao,Junqiang Zheng,Yanxin Mao,Guohai Liu 한국자기학회 2019 Journal of Magnetics Vol.24 No.4
This paper presents a new stator topology of fractional-slot concentrated-windings permanent-magnet (FSCWPM) machine in order to reduce the electromagnetic vibration. First of all, the space orders and corresponding frequencies of the lowest order radial force of FSCW-PM machines is studied. A 12-slot/10-pole FSCW-PM machine is used as an example, and its lowest order radial force harmonics are calculated by analytical method and finite element method, respectively. Then, in order to minimize the amplitude of the vibration acceleration, a new stator structure of 12-slot/10-pole machine is designed, by which the amplitude of the lowest order radial force is greatly reduced. Afterwards, the modal and vibration experiments are performed. The result shows that the 2<SUP>nd</SUP> order radial force with 2f0 frequency contributes most to overall vibration. Finally, vibration simulation models of both machines are established, the results show that the machine with unequal teeth design effectively reduce the electromagnetic vibration.
Haoen Xu,Jin Huang,Xinyu Xu,Junqiang Zheng 한국자기학회 2023 Journal of Magnetics Vol.28 No.3
This paper presents how to select the proper slot and pole combination (SPC) and reasonable rotor topologies for an interior permanent-magnet (IPM) machine. Firstly, the selection principle of SPC is reported, and some electromagnet performances, including winding factor, stator space magneto-motive force (MMF) harmonics, radial force harmonics, and cogging torque, are analyzed and compared. Secondly, four PM rotor topologies are designed and discussed, including surface permanent-magnet (SPM), spoke type, V-shape, and multi-layer reluctance (MR) type. Their performances, such as back-EMFs, torque, and ripple and flux-weakening capability, are thoroughly analyzed and compared by the finite-element method (FEM). Finally, a 27-slot and 8-pole V-shape IPM machine is selected and designed optimally, which offers high power/torque density, high efficiency, and less torque ripple. In order to ensure the reliability of its rotor mechanical strength, the equivalent stress and deformation are analyzed by ANASY. Besides, its d-q axis mathematical model is built to verify its performance further. Then experiments on the prototypes are carried out for validation.