• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.367-368
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• 2016

10kV IGCT has been recently developed and has the potential to push wind turbine systems to higher power and voltage rating. Converters employing IGCTs need snubber and OVP circuit to limit the rate of current's rising and peak over voltage across IGCT during turn on and off state, respectively. The conventional RCD snubber which is used in such power converter dissipates a significant amount of power. In order to reduce the amount of energy lost by conventional RCD snubber, this paper proposes flyback type snubber comprising two coils wound on a magnetic core. The flyback snubber not only meets all of the IGCTs characteristics during on and off-state but also significantly saves the power loss. Modern magnetic model using permeance-capacitance analogy leads to more accurate loss analysis of flyback type di/dt snubber circuit in 3-level NPC type back-to-back VSC. In turns, the comparison between conventional and flyback type snubber yield the effectiveness of proposed snubber in wind turbine systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1157-1164
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• 2007

Ceramic honeycomb structures have performed successfully as catalyst supports for meeting hydrocarbon, carbon monoxide and nitrous emissions standards for gasoline-powered vehicles. Three-way catalyst converter has to withstand high temperature and thermal stress due to pressure fluctuations and vibrations. Thermal stress constitutes a major portion of the total stress which the ceramic catalyst support experiences in service. In this study, temperature distribution was measured at ceramic catalyst supports. Thermal durability was evaluated by power series dynamic fatigue damage model. Radial temperature gradient was higher than axial temperature gradient. Thermal stresses depended on direction of elastic modulus. Axial stresses are higher than tangential stresses. Tangential and axial stresses remained below thermal fatigue threshold in all engine operation ranges.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4975-4983
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• 2010

In this paper, the ordinariest and strongest simulator that many used to power electronics circuits and many different control technology can apply to more easily understand modeling the element, PSPICE and MATLAB are adapted a micro IGBT, a macro IGBT, PWM generator and to library moeling of validity of the Induction motor is interpreted. Micro IGBT model of demagnetization quality proved for modeling accuracy to through experiment, macromodel IGBT were simulated which the applied to voltage type PWM inverter to the cyclo-converter and induction motor of demagnetization.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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• pp.175-181
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• 2015

In this study, a lithium polymer battery (LiPB) is simply expressed by a primary RC equivalent model. The PI state observer is designed in Matlab/Simulink. The non-linear relationship with the OCV-SOC is represented to be linearized with 0.1 pu intervals by using battery parameters obtained by constant-current pulse discharge. A state equation is configured based on battery parameters. The state equation, which applied Peukert's law, can estimate SOC more accurately. SOC estimation capability was analyzed by utilizing reduced Federal Test Procedure (FTP-72) current profile and using a bi-directional DC-DC converter at temperature ($25^{\circ}C$). The PI state observer, which is designed in this study, indicated a SOC estimation error rate of ${\pm}2%$ in any of the initial SOC states. The PI state observer confirms a strong SOC estimation performance despite disturbances, such as modeling errors and noise.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1046-1054
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• 2014

In this paper, a hardware prototype for the 10kVA 11-level MMC was built and various experimental works were conducted to verify the operation algorithms of MMC. The hardware prototype was designed using computer simulation with PSCAD/EMTDC software. After manufactured in the lab, the hardware prototype was tested to verify the modulation algorithms to form the output voltage, the balancing algorithm to equalize the sub-module capacitor voltage, and the redundancy operation algorithm to improve the system reliability. The developed hardware prototype can be utilized for analyzing the basic operation and performance improvement of MMC according to the modulation and redundancy operation scheme. It also can be utilize to analyze the basic operational characteristics of HVDC system based on MMC.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.1117-1125
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• 2000

A current mode PWM method applied one cycle response to averaging circuit model Buck converters is presented. The controller nonlinear PWM implement is based on the error between the switched variable and the response reference to zero each cycle. As the result, the system transfer function is derived as a function of the desired close loop poles, simplifying the design procedure and bringing forward all the important characteristics of the close loop system. The proposed controller has significant advantages over conventional current mode control methods in noise susceptibility, dynamic response and without inductor current sensing, Finally, the simulation and experiment results confirm the proposed PWM control techniques.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.3
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• pp.199-207
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• 2018

In this paper, an all-metal domestic induction heating (IH) system that can quickly identify ferromagnetic and non-ferromagnetic pots considering temperature changes in the working coil is designed. Load modeling is performed after analyzing the parameters of the pot material and the central misalignment of the working coil. To improve the performance and stability of the all-metal IH cooking heater, a power curve-fitting model is used to design a control system that quickly responds to load parameter fluctuations. In addition, a power control algorithm is established to compensate for the reference value by reflecting the increase in working coil temperature during heating of the non-ferromagnetic pot. The validity of the proposed control algorithm for the all-metal IH is verified by experiments using a 3.2 kW all-metal IH cooking heater.

• Korean Journal of Computational Design and Engineering
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• v.10 no.1
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• pp.1-10
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• 2005

This paper presents an embodiment of design integration framework corresponding to changes in the latest manufacturing environment. The embodied system is named by 'WEB-KBE System' because it supports a product design with a KBE technique based on web environment. The final purpose of the work is to implement a web-based integration design environment with a KBE technique to support non-skillful designers. The framework of the system Is designed to support necessary items in user-centric design environment. Two case studies were applied to the WEB-KBE system to evaluate the efficiency, flexibility, extensibility, and reusability of the system. The examples are [1] CART integration design environment construction and (2) Exhaust Duct Saddle Support integration design environment construction. In the former case, it took a period of 8 months for modeling and implementation of the WEB-KBE prototype system. However, with the high extensibility and reusability of WEB-KBE system, the second case required only a period of one month for modeling and implementation of the system. We conclude that the presented WEB-KBE system can bring fair effects on implementing a knowledge based design environment in aspect of time and expense.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.766-776
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• 2015

It is well known that series arc faults in Low Voltage DC (LVDC) distribution system occur at unintended points of discontinuity within an electrical circuit. These faults can make circuit breakers not respond timely due to low fault current. It, therefore, is needed to detect the series fault for protecting circuits from electrical fires. This paper proposes a novel scheme to detect the series arc fault using Wavelet Singular Value Decomposition (WSVD) and state diagram. In this paper, the fault detector developed is designed by using three criterion factors based on the RMS value of Singular value of Approximation (SA), Sum of the absolute value of Detail (SD), and state diagram. LVDC distribution system including AC/DC and DC/DC converter is modeled to verify the proposed scheme using ElectroMagnetic Transient Program (EMTP) software. EMTP/MODELS is also utilized to implement the series arc model and WSVD. Simulation results according to various conditions clearly show the effectiveness of the proposed scheme.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.12
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• pp.1596-1607
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• 2000

The optimal design of auto-catalyst needs a good compromise between the pressure drop and flow uniformity in the substrate. One of the effective methods to achieve this goal is to use the concept of radially variable cell density. But this method has not been examined its usefulness in terms of chemical behavior and conversion performance. In this work, two-dimensional performance prediction of catalyst coupled with turbulent reacting flow simulation has been used to evaluated the benefits of this method n the flow uniformity and conversion efficiency. The results showed that two cell combination of 93cpsc and 62 cpsc was the most effective for improved pressure drop and conversion efficiency due to balanced space velocity and efficient usage of geometric surface area of channels. It was also found that large temperature difference between the bricks in case that the edge of the frontal face of brick has too much lower cell density(less than 67% of cell density of the center of the brick). This study has also demonstrated that the present computational results show the better prediction accuracy in terms of CO, HC and NO conversion efficiencies compared to those of conventional 1-D adiabatic model by comparison with experimental results.