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열 사상법을 이용한 유도 기동형 동기 전동기의 비정상 3차원 열해석
김치원(Chiwon Kim),엄석기(Sukkee Um) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
This paper describes thermal modeling of a line start permanent magnet (LSPM) motor using a computational flow dynamics method. First, 2-dimensional electromagnetic design is carried out in order to comprehend heat losses at winding, stator, rotor and cage. New coupling method called Heat mapping method (HMM) will be introduced which converts 2-D information of electromagnetic domain to 3-D information of thermal domain. Transient thermal analysis under rated operating conditions is performed to identify the load saturation time and temperatures in the LSPM motor. Experimental results are collected under the same operating conditions and computational results are verified against the experimental data. Finally, thermal path analysis at a steady-state is conducted to figure out the direction and magnitude of heat flux in the LSPM motor. These results can be useful to design effective cooling systems of electrical motors.
차량용 연료전지 스택의 안정적 반응 가스 공급을 위한 중앙 유동 분배기 형상 설계에 관한 수치적 연구
정혜미(Jung, Hye-Mi),엄석기(Um, Suk-Kee),정희석(Jeong, Hui-Seok),이성호(Lee, Seong-Ho),서정도(Seo, Jeong-Do),손영진(Son, Yeong-Jin) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.05
In this study, two types of central flow distributor designs are presented and compared to obtain the optimal compact design which has the least flow resistance and the uniform flow distribution in a vehicular fuel cell stack. For effective and reliable prediction on the thermo-flow characteristics of the reactants flow over the entire fuel cell stack domain, open channel flow in the bipolar plates of the power generating cells were simulated by applying a simplified flow resistance model with an empirical porous concept. A number of case studies were performed to figure out an optimal configuration of a central flow distributor device in terms of the time-dependent thermo-flow behavior and load-dependent flow distribution. The results showed that the stable and load-independent thermo-flow uniformity is very design specific, which is closely associated with the design of central manifolding devices in order to achieve the enhanced volumetric power density and the reliable long-lasting operating of fuel cells.
고속ㆍ저토크용 표면부착형 영구자석 동기 전동기의 운전 안정성 확보를 위한 손실 및 열전달 특성 분석
최문석(Moon Suk Choi),엄석기(Sukkee Um) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.3
고속 저토크 표면 부착 영구자석형 동기 전동기의 운전 안정성 확보를 위하여 과속도 및 과부하 영역에서 전동기 코일 온도 예측이 필수적이다. 0.35mm 의 S18, S08 등급인 35PN440, 35PN220 그리고 0.15mm 의 저손실 재료인 15HTH1000 으로 제작된 고정자 철심을 포함하는 전동기의 정격 구동 조건에서 손실 및 코일 온도를 측정하여 과속도 및 과부하 영역의 손실 및 열저항을 예측하고 열전달 모델링을 수행하였다. 이의 검증을 위하여 무부하 과속도 영역에서 계산된 코일 온도와 실험값을 비교하여 6.4%이하로 일치하였다. 35PN440 을 적용한 전동기에 비하여 15HTH100 을 적용한 전동기는 무차원 회전속도 0.9, 부하율 3.0 일 때 철손실이 84.4% 로 감소하였고, 무차원 코일 온도 1.0 을 기준으로 출력이 85.2% 향상되었다. 정격 구동 영역의 손실 측정 및 열전달 모델링으로 과부하 및 과속도 영역에서 철심 재질에 따른 코일 온도 변화 및 전동기 출력 개선량을 정확하게 예측할 수 있음을 알 수 있다. It is essential to predict the coil temperature under over load and over speed conditions for reliability in high speed low torque surface mounted PM synchronous motors(SPM). In the present study, the losses and coil temperature are measured under rated condition and calculated under over speed and over load conditions in the three different motors with 35PN440, 25PN250 and 15HTH1000. The heat transfer modeling has been performed based on acquired losses and temperature. The difference of coil temperature between heat transfer modeling and experiment is less than 6.4% under no load, over speed and over load conditions. Subsequently, the coil temperature of the motor with 15HTH1000 is 84.4% of the coil temperature of the motor with 35PN440 when speed is 0.9 and load is 3.0. The output of motor with 15HTH1000 is 85.2% greater than the output of the motor with 35PN440 when the dimensionless coil temperature is 1.0.
정혜미(JUNG, Hye-Mi),엄석기(UM, Sukkee),박정선(PARK, Jungsun),이원용(LEE, Won-Yong),김창수(KIM, Chang-Soo) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06
The effects of internal manifold designs the reactant feed-stream in Polymer Electrolyte Fuel Cells (PEFCs) is studied to figure out mass flow-distribution patterns over an entire fuel cell stack domain. Reactants flows are modeled either laminar or turbulent depending on regions and the open channels in the bipolar plates are simulated by porous media where permeability should be pre-determined for computational analysis. In this work, numerical models for reactant feed-stream in the PEFC manifolds are classified into two major flow patterns: Z-shape and U-shape. Several types of manifold geometries are analyzed to find the optimal manifold configurations. The effect of heat generation in PEFC on the flow distribution is also investigated applying a simplified heat transfer model in the stack level (i.e. multi-cell electrochemical power-generation unit). This modeling technique is well suited for many large scale problems and this scheme can be used not only to account for the manifold flow pattern but also to obtain information on the optimal design and operation of a PEMC system.