• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1081-1083
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• 1999

The capacitive coupling technique has been used as conventional method for PD detection on the power cable line. Recently, however PD measurement using by high frequency is known to have an excellent sensitivity comparison with low frequency on-site. In this paper, the high frequency characteristic of two type of metal foil sensor was studied and the technique was proved to be more effective diagnostic method than conventional method for qualification of EHV cable and accessories.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.200-202
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• 2006

In this paper, a novel type of auxiliary active snubbing circuit assisted quasi-resonant soft-switching pulse width modulation inverter is proposed for consumer induction heating equipments. The operation principle of this high frequency inverter is described using switching modes and equivalent circuits. This newly developed series resonant high frequency inverter can regulate its high frequency output AC power under a principle of constant frequency active edge resonant soft-switching commutation by asymmetrical PWM control system. The high frequency power regulation and actual power conversion efficiency characteristics of consumer induction heating (IH) products using the proposed soft-switching pulse width modulation (PWM) series load resonant high frequency inverter evaluated. The practical effectiveness and operating performance of high frequency inverter are discussion on the basis of simulation and experimental results as compared with the conventional soft-switching high frequency inverter.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.3
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• pp.280-289
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• 2024

In this study, a cryogenic vessel was constructed to maintain and control the safe pressure of liquid hydrogen boil-off gas (BOG), and the numerical analysis was conducted on the development of computational fluid dynamics model inside the high-pressure vessel. An evaluation system was constructed using cryogenic inner and outer containers, pre-cooler, upper flange, and internal high-pressure container. We attempted to analyze the performance of the safety valve by injecting relatively high temperature hydrogen gas to generate BOG gas and quickly control the pressure of the high-pressure vessel up to 10 bar. As a results, the liquid volume fraction decreased with a rapid evaporation, and the pressure distribution increased monotonically inside a high pressure vessel. Additionally, it was found that the time to reach 10 bar was greatly affected by the filling rate of liquid hydrogen.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.5
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• pp.373-381
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• 2017

The electric vehicle market has increased rapidly in recent years. Established global automakers have announced that electric cars will be developed and distributed. Furthermore, current electric cars are not merely breezes, instead, they are the mainstream of automobiles. However, high prices, short mileage, and long charge times are the main obstacles to the spread of electric vehicles. To solve these problems, the competition for technology development for the expansion of electric vehicles worldwide intensifies because of the improvements in mileage, price reduction, and expansion of charging infrastructure. In this paper, the trends in the development of key technologies for electric vehicles in overseas markets and the present strategic goals for the development of key technologies for electric vehicles in Korea will be identified.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.226-228
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• 2006

This paper presents the two lossless auxiliary inducors-assisted voltage source type half bridge(single ended push pull:SEPP) series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation forwide its output power regulation ranges and load variations under constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operatprinciple is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation charactertics-based on the high frequency PDM strategy. The experimenoperating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimenones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliimplemented here is proved from the practical point of view.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2164-2166
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• 1999

This paper is describes the measured electric field waveform radiated by lightning discharge. We have performed measurement and analysis of the electric fields associated with stepped leaders. Electric field measurement system was composed of hemisphere electric field sensor, measurement system of a distance from lightning strokes, automatical recording system, A/D board, personal computer etc. A/D board have high sampling time, high speed data processing, 8bit of resolution. Also, measured characteristics of stepped leaders radiated by were analyzed.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1051-1053
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• 1999

In this work, thermal phenomena and temperature rise due to thermal source in electric switchboard were investigated using analytical measures. Electric switchboards are assemblies of panels on which are mounted switches, circuit breakers, high current busbars, meter, fuses and terminals essential to the operation of electric equipment. It is very difficult to predict the temperature rise in switchboard due to the existence of several heat sources. To overcome this situations, we focused on the eddy current distribution on the panel of switchboard caused by high current busbars as a fundamental basis. And thermal sources including busbar and switchgear have been considered. Furthermore, thermal transfer phenomena in switchboard was considered theoretically. Finally, three-dimensional thermal model for eddy current analysis has been adopted and FEM analysis was conducted. As a result, three-dimensional numerical analysis found to be applicable to the analysis of thermal phenomena in switchboard.

• International Journal of Advanced Culture Technology
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• v.11 no.1
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• pp.337-342
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• 2023

Since the electric vehicle uses an electric motor, problems have arisen as the driver hears the inherent noise of the motor or external noise, which was not a problem in the past, due to the overall lower noise environment than when using an internal combustion engine. Therefore, the purpose of this paper is to reduce the noise and vibration of electric motors for electric vehicles, and recently, to increase the speed of high-power, high-efficiency electric motors in a small size, and to develop low-noise motors, IPM motors are applied to produce 35KW electric motors for electric vehicles. A motor for low noise was designed and implemented. N-T Curve and efficiency map were confirmed as the final result of developing a 35KW low-noise motor for electric vehicles by applying the IPM motor applied in this paper. Based on 3500 rpm, Max Torque [Nm]: 121.15, Max Power [KW]: 44.04, and Max Efficiency [%]: 97.65, showing high efficiency.

• Journal of Electrical Engineering and Technology
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• v.8 no.3
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• pp.530-543
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• 2013

This paper describes a control scheme of speed sensorless fuzzy direct torque control (FDTC) of permanent magnet synchronous motor for electric vehicle (EV). Electric vehicle requires fast torque response and high efficiency of the drive. Speed sensorless FDTC In-wheel PMSM drives without mechanical speed sensors at the motor shaft have the attractions of low cost, quick response and high reliability in electric vehicle application. This paper presents a new approach to estimate the speed of in-wheel electrical vehicles based on Model Reference Adaptive System (MRAS). The direct torque control suffers in low speeds due to the effect of changes in stator resistance on the flux measurements. To improve the system performance at low speeds, a PI-fuzzy resistance estimator is proposed to eliminate the error due to changes in stator resistance. High performance sensorless drive of the in-wheel motor based on MRAS with on line stator resistance tuning is established for four motorized wheels electric vehicle and the whole system is simulated by matalb/simulink. The simulation results show the effectiveness of the new control strategy. This proposed control strategy is extensively used in electric vehicle application.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2040-2045
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• 2015

This paper deals with the electromagnetic and thermal analysis of high speed induction motor. The induction motor is analyzed by time-varying magnetic finite element method and its thermal analysis is carried out by using analytical lumped-circuit method. Analysis results are compared with the experiment of 29kW high speed motor prototype at 12,000rpm.