• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.24-26
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• 2003

본 연구에서는 고효율, 반영구적인 수명 및 환경친화성으로 인해 효과적인 전력저장장치로 대두되고 있는 플라이휠 에너지 저장시스템 (FESS : Flywheel Energy Storage System)의 구동원으로 적용되는 전동발전기와 전력변환기에 대한 설계 및 제작을 수행하였다. 연구 대상 FESS의 저장용량은 5[kWh]이며 운전 속도는 30,000rpm이다. 전동발전기는 슬롯리플에 의한 와전류 손실이나 열손실을 고려하여 슬롯리스 Ring-wound형으로 선정하였으며, 전력변환기는 PWM Boost 컨버터를 통해 역률 및 DC 전압제어 그리고 Full Bridge 인버터를 통해 전동발전기 고속운전 제어를 실현할 수 있는 Topology를 채택하였다.

• Superconductivity and Cryogenics
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• v.7 no.2
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• pp.17-20
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• 2005

• Superconductivity and Cryogenics
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• v.8 no.2
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• pp.15-19
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• 2006

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.963-967
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• 2007

Flywheel energy storage systems (FESS) have advantages over other types of energy storage methods due to their infinite charge/discharge cycles and environmental friendliness. The system has two radial bearings and one hybrid-thrust bearing. Thrust hybrid-type bearing use permanent magnet to relieve gravity load. The radial bearings were designed to provide sufficient force slew rate considering the unbalance disturbance at the operating speeds. In this paper, we will derive dynamic model of hybrid-type bearing using permanent magnet for thrust bearing and present simulation and stability of the model.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.3-5
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• 2004

본 연구에서는 고효율, 반영구적인 수명 및 환경친화성으로 인해 효과적인 전력저장장치로 대두되고 있는 플라이휠 에너지 저장(SFES : Super-conductivity Flywheel Energy Storage) 시스템의 구동원으로 적용되는 전동발전시스템에 대한 설계, 제작 및 시험을 수행하였다. 전동발전기는 슬롯리플에 의한 와전류 손실이나 열손실을 고려하여 슬롯리스 Ring-wound형으로 선정하였으며, 전력변환기는 PWM Boost 컨버터를 통해 역률 및 DC 전압 제어 그리고 Full Bridge 인버터를 통해 전동발전기 고속운전 제어를 실현할 수 있는 Topology를 채택하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.122-128
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• 1997

초전도체의 임계온도를 높이는 연구들이 수행되어 임계온도가 액체질소의 비등점(77K)보다 높은 산화물 고온 초전도체가 1986년에 발견되었고, 최근에는 $10^4A/cm^2$이상의 임계전류밀도를 갖는 덩어리형 고온 초전도체가 용융공정을 통해 개발되었으며, 산화물 고온 초전도체 $YBa_2 Cu_3 O_{7-y}$은 산소 조성이 7에 가까우며 임계온도가 95K로서 현재 가장 많이 사용되고 있다. 응용 분야로서는 수송분야, 의료분야, 전력분야, 그리고 기초과학분야등이 있고, 향후 상온 초전도체의 출현으로 인한 응용범위의 확대는 획기적일 것으로 예측되어 진다. 이중에 10$^{-8}$이하의 마찰계수를 갖는 초전도 마그네틱 베어링을 플라이휠 같은 에너지 저장장치에 적용시키는 연구가 국내외적으로 진행되고 있다. 여러 선진국에서는 용융공정된 초전도체를 이용하여 실험단계적인 플라이휠의 설계, 제작 및 성능실험을 진행중이거나 완성하였고, 제2단계 목표로서 실용화를 위한 대규모 플라이휠의 설계와 제작에 대한 연구가 진행중이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.12
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• pp.1096-1101
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• 2008

When we design a controller for the active magnetic bearings that support a large rotor, it is important to have an accurate model of the rotor. For the case of the flywheel that is used to store energy, an accurate rotor model is especially important because the dynamics change with respect to the running speed due to gyroscopic effects. In this paper, we present a procedure of obtaining an accurate rotor model of a large flywheel energy storage system using finite-element method. The model can predict the first and the second bending mode which match well with the experimental results obtained from a prototype flywheel energy storage system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1665-1674
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• 1995

An optimum design has been performed to maximize specific energy (SED) of composite flywheel rotor for energy storage system. The flywheel rotor is assumed to be an axisymmetric thick laminated shell with a plane strain state for structural analysis. For the structural analysis the centrifugal force is considered and the stiffness matrix equation was derived for each ring considering the interferences between the rings. The global stiffness matrix was derived by integrating the local stiffness matrix satisfying the conditions of force and displacement compatibilities. Displacements are then calculated from the global stiffness matrix and the stresses in each ring are also calculated. 3-D intra-laminar quadratic Tsai-Wu criterion is then used for the strength analysis. An optimum procedure is also developed to find the optimal interferences and lay up angle to maximize SED using the sensitivity analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1757-1763
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• 2010

Flywheel energy storage system (FESS) is defined as a high speed rotating flywheel system that can save surplus electric power. The FESS is proposed as an efficient energy storage system because it can accumulate a large amount of energy when it is operated at a high rotating speed and no mechanical problems are encountered. The FESS consists of a shaft, flywheel, motor/generator, bearings, and case. It is difficult to simulate rotor dynamics using common structure simulation programs because these programs are based on the 3D model and complex input rotating conditions. Therefore, in this paper, a program for the FESS based on the 2D FEM was developed. The 2D FEM can model easier than 3D, and it can present the multi-layer rotor with different material each other. Stiffness changing of the shaft caused by shrink fitting of the hub can be inputted to get clear solving results. The results obtained using the program were compared with those obtained using the common programs to determine any errors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.357-358
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• 2008