• The Transactions of the Korean Institute of Power Electronics
• /
• v.4 no.6
• /
• pp.547-553
• /
• 1999

A new multi-step voltage source inverter is proposed in this paper. The proposed scheme is composed of t the double-connected 12-step inverter with an auxiliary circuit. The auxiliary circuit includes two voltage d dividing capacitors, two switching devices and a low KV A autotransformer. The resultant system is shown to b be a 24-step inverter suitable for medium power level SVC applications in which the PWM method can not be e employed. A 36-step operation can also be 이)tained by the addition of a bidirectional switch to the ProlXlsed I inverter. The design parameters are derived from the analysis of voltages and currents by means of switching f functions. The validity of the proposed scheme is confirmed by the simulated and experimental results.

• Journal of the Korean Society of Mechanical Technology
• /
• v.20 no.6
• /
• pp.783-789
• /
• 2018

This paper investigates the relationship of voltage and current waveform between normal piezo injector and deterioration abnormal piezo injector. The experimental methods using Pico oscilloscope and GDS scan tool are employed to measure current and voltage waveform and fuel pressure of piezo injector. The experiment is carried out during no-load condition. A summary of the important results are as follows. 1) In case of normal injector, the fluctuation of duration time of piezo injector was linearly and regularly decreased with increasing engine speed, but the that of deterioration piezo injector was irregularly decreased with increasing engine speed. 2) In main injection, the peak value of the current waveform of abnormal injector was larger than that of normal injector, the duration time of deteriorated abnormal injector was less than that of normal injector at 800rpm and 1500rpm, but the duration time of deteriorated abnormal injector was larger than that of normal injector at 2000rpm and 3000rpm. This irregularity appears to be caused by the deterioration of the injector.

• Proceedings of the KIEE Conference
• /
• 1997.07f
• /
• pp.2152-2154
• /
• 1997

본 논문은 복잡한 스위칭 변조없이 입력역률과 입력 전류파형을 향상시키는 우수한 정현 컨버터를 제안하고자 한다. 그 구성과 제어방법은 비교적 단순하지만 정현컨버터는 입력 선전류에 포함된 무효전력과 고조파를 효과적으로 감소시킴으로서 우수한 동작 특성을 이론적 분석과 Pspice 시뮬레이션을 통하여 입증하고자 한다.

• Proceedings of the KIPE Conference
• /
• 2011.07a
• /
• pp.56-57
• /
• 2011

본 논문에서는 10kW급 3상 백투백 컨버터에 필요한 여러가지 제어 기술들을 살펴보고 시뮬레이션을 통해 제어 알고리즘의 타당성을 분석하며, 실제 하드웨어의 구성 및 계통연계 실험을 통해 입, 출력 전압, 전류 등 파형을 관찰하여 3상 백투백 컨버터의 타당성과 적정성을 알아본다.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.906-907
• /
• 2015

본 논문은 3상 12/10 스위치드 릴럭턴스 모터의 구조를 설명하였고, 토크를 구하는데 중요한 값인 인덕턴스와 전류 파형을 구하기 위해 스위치드 릴럭턴스 모터의 변수를 드웰각과 선행각으로 정하였다. 두 변수의 범위에 따른 25개의 샘플링를 통해서 2차원 유한요소 해석을 이용하여 토크 리플과 평균 토크를 얻었고 그 결과를 분석하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.6
• /
• pp.521-521
• /
• 2020

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.12
• /
• pp.2618-2624
• /
• 2009

Harmonics (or distortion in wave form) has always existed in electrical power systems. It is harmless as long as its level is not substantial. However, with the recent rapid advancement of power electronics technology, so-called nonlinear loads, such as variable frequency drives for motor power/speed control, are increasingly finding their way to shipboard or offshore applications. In this paper a new approach to direct torque control (DTC) of induction motor drive is presented. In comparison with the conventional DTC methods the inverter switching frequency is constant and is dramatically increased, requiring neither any increase of the sampling frequency, nor any high frequency dither signal. The well-developed space vector modulation technique is applied to inverter control in the proposed DTC-based induction motor drive system, thereby dramatically reducing the current harmonics. As compared to the existing DTC approach with constant inverter switching frequency, the presented new approach does not invoke any concept of deadbeat control, thereby dramatically reducing the computations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.4
• /
• pp.72-77
• /
• 2006

This paper presents the transient impedance behaviors according to the length of down conductors of grounding systems to lightning impulse currents. The potential rise and effective impulse ground impedance of the deeply-driven ground rod and grounding grid subjected to the impulse currents were measured and analyzed as a function of the rise time of impulse currents and lengths of down conductor. The transient ground impedances strongly depend on the configuration and size of grounding electrodes, the waveform of impulse currents and the length of down conductors, and the installation methods reducing the inductance of down conductors are an important factor to decrease the transient ground impedances.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.5
• /
• pp.126-132
• /
• 2007

We propose a power factor correction scheme using a LC resonant circuit in commercial frequency without switching devices. In this method, It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency, Hence, the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh orders are much reduced. The result are confirmed by the theoretical and experimental implementations

• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.756-759
• /
• 2004

실제 3상 시스템에서의 공급전압은 다양한 이유로 인하여 불평형이 되는데, 정류시스템의 특성과 입력 전류의 질은 이 같은 불평형의 증가와 함께 더 나빠지게 된다. 또한 정류기 선전류 고조파는 전력시스템의 동작을 방해하고, 정류기 역률을 줄이며, 공급되는 전력으로부터 사용 가능한 전력을 제한하게 된다. 이에 정류기의 출력 필터 인덕턴스의 적절한 설계가 정류기 선전류 파형과 선전류 고조파, 역률을 결정하는 중요한 역할을 하게 된다. 이에 이 논문에서는 출력 필터 인덕턴스 값의 변화에 따른, 단상과 삼상 정류기의 선전류 고조파와 역률을 해석하고, 또한 지금까지 3상 평형상태의 전압에서만 해석되어 오던 것을 3상 불평형상태의 공급전압에까지 확대하여 성능을 평가하였다. 그리고 그것은 $5\%,\;10\%,\;15\%$의 3가지의 불평형 레벨을 가지고 해석 되었고, 시뮬레이션과 실제적인 실험을 통하여 적절한 출력 필터 인덕턴스의 디자인 값을 선정하는데 기준을 제시하였다.