Thermal Analysis of High Density Permanent Magnet Synchronous Motor Based on Multi Physical Domain Coupling Simulation

ShiJun Chen,Qi Zhang,Biao He,SuRong Huang,Dou-Dou Hui 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.1

In order to meet the thermal performance analysis accuracy requirements of high density permanent magnet synchronous motor (PMSM), a method of multi physical domain coupling thermal analysis based on control circuit, electromagnetic and thermal is presented. The circuit, electromagnetic, fluid, temperature and other physical domain are integrated and the temperature rise calculation method that considers the harmonic loss on the frequency conversion control as well as the loss non-uniformly distributed and directly mapped to the temperature field is closer to the actual situation. The key is to obtain the motor parameters, the realization of the vector control circuit and the accurate calculation and mapping of the loss. Taking a 48 slots 8 poles high density PMSM as an example, the temperature rise distribution of the key components is simulated, and the experimental platform is built. The temperature of the key components of the prototype machine is tested, which is in agreement with the simulation results. The validity and accuracy of the multi physical domain coupling thermal analysis method are verified.

Thermal Analysis of High Density Permanent Magnet Synchronous Motor Based on Multi Physical Domain Coupling Simulation

Chen, ShiJun,Zhang, Qi,He, Biao,Huang, SuRong,Hui, Dou-Dou The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.1

In order to meet the thermal performance analysis accuracy requirements of high density permanent magnet synchronous motor (PMSM), a method of multi physical domain coupling thermal analysis based on control circuit, electromagnetic and thermal is presented. The circuit, electromagnetic, fluid, temperature and other physical domain are integrated and the temperature rise calculation method that considers the harmonic loss on the frequency conversion control as well as the loss non-uniformly distributed and directly mapped to the temperature field is closer to the actual situation. The key is to obtain the motor parameters, the realization of the vector control circuit and the accurate calculation and mapping of the loss. Taking a 48 slots 8 poles high density PMSM as an example, the temperature rise distribution of the key components is simulated, and the experimental platform is built. The temperature of the key components of the prototype machine is tested, which is in agreement with the simulation results. The validity and accuracy of the multi physical domain coupling thermal analysis method are verified.

Excellent Strengthening of Low-Carbon Steel by Severe Free-End Torsion

Shijun Tan,Bo Song,Hongbing Chen,Xiaodong Tan,Risheng Qiu,Tingting Liu,Ning Guo,Shengfeng Guo 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.8

In this work, the effects of free-end torsion on microstructure and tensile property of low-carbon steel were investigated indetail. Low-carbon steels exhibited exceptionally high yield strength through severe torsion deformation. Such high hardeningeffect was mainly attributed to the severe lattice distortion, high density of dislocations and the change in grain shape. Moreover, a gradient deformation structure can be introduced by torsion deformation. The gradient-structure can generate ahigh hetero-deformation induced strengthening, which can increase the strain hardening capacity and remain high plasticity/toughness. Therefore, with increasing torsion angle from 700 to 2800 deg., the uniform elongation and the peak strength werelargely enhanced. After twisting 2800 deg., yield strength and peak strength can achieve 524 MPa and 675 MPa, respectively,and good tensile elongations (εf = 9.6%, εu = 7.4%) are remained.

NONLINEAR OPTICAL PROPERTIES OF THE WURTZITE InGaN/AlGaN PARABOLIC QUANTUM DOT

TAIRONG CHEN,Wenfang Xie,Shijun Liang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.2

The linear and nonlinear optical properties in a wurtzite InxGa1-xN/AlyGa1-yN strained spherical quantum dot (QD) subjected to a uniform external electric field with a direction opposite to that of the built-in electric (BEF) within the framework of effective-mass approximation have been investigated. The results show that the BEF has great effects on the linear and nonlinear optical absorption coefficients (ACs) and refractive index (RI) changes. Moreover, the dependence of the linear and nonlinear optical properties on the In composition, on the Al composition and on the inner sphere radius has been studied in detail. It is indicated that the ACs and RI changes of the Wurtzite spherical QD have strongly affected by these factors. The results may make a significant contribution to designing some important photodetectors and photonic crystal devices.

Response variability of juvenile hormone and juvenile hormone analogs in workers of the Formosan subterranean termite (Coptotermes formosanus Shiraki)

He Du,Shijun Zhang,Yong Chen,Yunling Ke,Shi Chen,Xueyi Huang,Zhiqiang Li 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.4

Juvenile hormone (JH) or juvenile hormone analog (JHA) can induce soldier formation in termites. However, different studies have yielded inconsistent results on the effects of JHA on soldier production in Coptotermes formosanus Shiraki. Using filter paper as the testing substrate, the effects of JH III, pyriproxyfen and methoprene on the intact filter paper left, worker mortality and presoldier formation were tested on six colonies. Our results showed that pyriproxyfen and methoprene were more repellent than JH III. No significant difference in toxicity was observed among methoprene, pyriproxyfen and JH III. JH III and pyriproxyfen did not cause workers to differentiate into presoldiers, but methoprene can induce formation of presoldiers. Colony response variability to methoprene was observed. The confirmation of the effects of JH/JHA on C. formosanus establishes the foundation for molecular studies of soldier differentiation in this species.

BMB Reports : Poly(ADP-ribose) protects vascular smooth muscle cells from oxidative DNA damage

( Chao Zhang ),( Tao Luo ),( Shijun Cui ),( Yongquan Gu ),( Chunjing Bian ),( Yibin Chen ),( Xiaochun Yu ),( Zhonggao Wang ) 생화학분자생물학회(구 한국생화학분자생물학회) 2015 BMB Reports Vol.48 No.6

Vascular smooth muscle cells (VSMCs) undergo death during atherosclerosis, a widespread cardiovascular disease. Recent studies suggest that oxidative damage occurs in VSMCs and induces atherosclerosis. Here, we analyzed oxidative damage repair in VSMCs and found that VSMCs are hypersensitive to oxidative damage. Further analysis showed that oxidative damage repair in VSMCs is suppressed by a low level of poly (ADP-ribosyl)ation (PARylation), a key post-translational modification in oxidative damage repair. The low level of PARylation is not caused by the lack of PARP-1, the major poly(ADP-ribose) polymerase activated by oxidative damage. Instead, the expression of poly(ADP-ribose) glycohydrolase, PARG, the enzyme hydrolyzing poly(ADP-ribose), is significantly higher in VSMCs than that in the control cells. Using PARG inhibitor to suppress PARG activity facilitates oxidative damage-induced PARylation as well as DNA damage repair. Thus, our study demonstrates a novel molecular mechanism for oxidative damage-induced VSMCs death. This study also identifies the use of PARG inhibitors as a potential treatment for atherosclerosis. [BMB Reports 2015; 48(6): 354-359]

Evaluation of Renal Oxygenation Level Changes after Water Loading Using Susceptibility-Weighted Imaging and T2* Mapping

Jiule Ding,Wei Xing,Dongmei Wu,Jie Chen,Liang Pan,Jun Sun,Shijun Xing,Yongming Dai 대한영상의학회 2015 Korean Journal of Radiology Vol.16 No.4

To assess the feasibility of susceptibility-weighted imaging (SWI) while monitoring changes in renal oxygenation level after water loading. Thirty-two volunteers (age, 28.0 ± 2.2 years) were enrolled in this study. SWI and multi-echo gradient echo sequence-based T2* mapping were used to cover the kidney before and after water loading. Cortical and medullary parameters were measured using small regions of interest, and their relative changes due to water loading were calculated based on baseline and post-water loading data. An intraclass correlation coefficient analysis was used to assess inter-observer reliability of each parameter. A receiver operating characteristic curve analysis was conducted to compare the performance of the two methods for detecting renal oxygenation changes due to water loading. Both medullary phase and medullary T2* values increased after water loading (p < 0.001), although poor correlations were found between the phase changes and the T2* changes (p > 0.05). Interobserver reliability was excellent for the T2* values, good for SWI cortical phase values, and moderate for the SWI medullary phase values. The area under receiver operating characteristic curve of the SWI medullary phase values was 0.85 and was not different from the medullary T2* value (0.84). Susceptibility-weighted imaging enabled monitoring changes in the oxygenation level in the medulla after water loading, and may allow comparable feasibility to detect renal oxygenation level changes due to water loading compared with that of T2* mapping.