• 전기학회논문지
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• 제58권1호
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• pp.199-202
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• 2009

Scan design is currently the most widely used structured Design For Testability approach. In scan design, all storage elements are replaced with scan cells, which are then configured as one or more shift registers(also called scan chains) during the shift operation. As a result, all inputs to the combinational logic, including those driven by scan cells, can be controlled and all outputs from the combinational logic, including those driving scan cells, can be observed. The scan inserted design, called scan design, is operated in three modes: normal mode, shift mode, and capture mode. Circuit operations with associated clock cycles conducted in these three modes are referred to as normal operation, shift operation, and capture operation, respectively. In spite of these, scan design methodology has defects. They are power dissipation problem and test time during test application. We propose a new methodology about scan shift clock operation and present low power scan design and short test time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.212-214
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• 2009

The polymer electrolyte membrane fuel cell(PEMFC) with the advantages of low-operating temperature, high current density, low cost and volume, fast start-up ability, and suitability for discontinuous operation becomes the most reasonable and attractive power system for transportation vehicle and micro-grid power plant in a household. 200W PEMFC(Polymer electrolyte membrane fuel cell) system applied to middle and small-scaled micro-grid power system was constructed by this study, then the electrical characteristics and diagnosis of the fuel cell were analyzed with thermal variation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.617-618
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• 2012

Recently as the inactive response characteristics of the existing RCD(Residual Current protective Device) used on low voltage power distribution system, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore, this paper is proposed a prevention apparatus using neutral line voltage and semiconductor switching devices for the prevention of electrical disasters in low voltage power distribution system caused by overload or electric short circuit faults. The proposed prevention apparatus confirms the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker(RCD) through various operation performance analysis.

• Journal of Power Electronics
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• 제15권3호
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• pp.806-818
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• 2015

Based on the inherent relationship between dc-bus voltage and grid feeding active power, two dc-bus voltage regulators with different references are adopted for a grid-connected PV inverter operating in both normal grid voltage mode and low grid voltage mode. In the proposed scheme, an additional dc-bus voltage regulator paralleled with maximum power point tracking controller is used to guarantee the reliability of the low voltage ride-through (LVRT) of the inverter. Unlike conventional LVRT strategies, the proposed strategy does not require detecting grid voltage sag fault in terms of realizing LVRT. Moreover, the developed method does not have switching operations. The proposed technique can also enhance the stability of a power system in case of varying environmental conditions during a low grid voltage period. The operation principle of the presented LVRT control strategy is presented in detail, together with the design guidelines for the key parameters. Finally, a 3 kW prototype is built to validate the feasibility of the proposed LVRT strategy.

• Journal of Electrical Engineering and Technology
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• 제6권4호
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• pp.474-483
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• 2011

Solid-state fault current limiters (SSFCL) in power systems are alternative devices to limit prospective short circuit currents from reaching lower levels. Fault current limiters (FCL) can be classified into two categories: R-type (resistive) FCLs and L-type (inductive) FCLs. L-type FCL uses an inductor to limit fault level and is more efficient in suppressing voltage drop during a fault. In contrast, R-type FCL is constructed with a resistance and is more effective in consuming the acceleration energy of generators during a fault. Both functions enhance the transient stability of the power system. In the present paper, a novel SSFCL is proposed to enhance power system transient stability and power quality. The proposed SSFCL uses both functions of an L-type and R-type FCL. SSFCL consists of four diodes, one self-turn-off IGCT, a current-limiting by-pass inductor (L), and a variable resistance parallel with an inductor for improvement of power system stability and prevention of over-voltage across SSFCL. The main advantages of the proposed SSFCL are the simplicity of its structure and control, low steady-state impedance, fast response, and the existence of R-type and Ltype impedances during the fault, all of which improve power system stability and power quality. Simulations are accomplished in PSCAD/EMTDC.

• 전력전자학회논문지
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• 제20권4호
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• pp.351-355
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• 2015

This paper explained the application of a lithium-ion battery energy storage system to electric propulsion ships. The power distribution in electric propulsion ships has low power quality because of the variation in the power consumption of the propulsion motor. For proper operation of the ship, the power quality needs to be improved, and the battery energy storage system is used to solve power-quality problems. The simulation models of electric propulsion ship and battery energy storage systems are constructed on MATLAB/Simulink to verify the improvement in power quality. The proposed system is applied in various scenarios of the propulsion motor state. The power quality achieved by using the battery energy storage system in both voltage and frequency satisfies the standards set by IEC-60092/101.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.75-76
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• 2007

Several kinds of High Temperature Superconducting(HTS) power cables have already been developed and evaluated for use in the utility power network. HTS power cable is expected to be used as a very powerful energy delivery system supplying electric power for densely populated cities in the near future, because HTS power cable is capable of the high current density delivery with low AC loss and the size effect comparing with the conventional cable whose capacity is same. Before applying the HTS power cable to real utility network system analysis should be carried out by some simulation tools. Hereby the electrical power system analysis is very important for the practical use of HTS power devices. In this paper, authors propose a real-time simulation method which incorporates a real HTS tapes into the simulated 22.9kV utility power network system using Real Time Digital Simulator(RTDS). For the simulation analysis, a test sample of HTS tapes was actually manufactured, and the transient phenomenon of HTS power cable system was analyzed in the simulated utility power network.

• 전자공학회논문지B
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• 제31B권7호
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• pp.42-48
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• 1994

In this paper, a low power and high speed flash Analog-to-Digital Converter using current-mode concept is proposed. Current-mode approach offers a number of advantages over conventional voltage-mode approach, such as lower power consumption small chip area improved accuracy etc. Rescently this concept was applied to algorithmic A/D Converter. But, its conversion speed is limited to medium speed. Consequently this converter is not applicable to the high speed signal processing system. This ADC is fabricated in 1.2um double metal CMOS standard process. This ADC's conversion time is measured to be 7MHz, and power consumption is 2.0mW, and differential nonlinearity is less than 1.14LSB and total harmonic distortion is -50dB. The active area of analog chip is about 350 x 550u$m^2$. The proposed ADC seems suitable for a single chip design of digital signal processing system required high conversion speed, high resolution small chip area and low power consumption.

• 한국정보통신학회논문지
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• 제6권3호
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• pp.421-426
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• 2002

Hybrid cascade multilevel PWM inverter has advantages of hybrid structure which enhances the better utilization of power semiconductor switches, that is, both hi호 power-low frequency switch, GTO and low power-high frequency switch, IGBT can be used in the same circuit. In this paper, a static var compensator using hybrid cascade 5-level PWM inverter is presented for high voltage/high power applications. The proposed system is modelled by circuit DQ transformation, and thus an equivalent circuit is obtained which reveals the important characteristics of the system and lead to the related equations. Finally, circuit structure and characteristics is presented and the validity of the characteristics analysis is shown through PSIM simulation.

• 전력전자학회논문지
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• 제4권1호
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• pp.82-90
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• 1999

본 논문은 단일 스위치 3상 ZCS 강압형 정류기의 펄스주파수 제어기법을 다루고 있다. 제안하는 펄스주파수 제어방법은 거의 정현적인 입력전류를 흐르게 하여 3상 강압형 정류기의 성능을 보여준다. 제안하는 제어구조의 유용성을 검증해 주는 시뮬레이션과 실험 결과는 단일 스위치 3상 ZCS 강압형 정류기의 고역율, 입력전류의 낮은 THD, 부하 변동에 대한 전압의 응답특성들이 뛰어남을 보여준다.