• Journal of Power Electronics
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• 제11권6호
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• pp.904-913
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• 2011

Previous publications regarding the design and specifications of input filters for STATCOMs usually deal with the input filter only, and seldom pay any attention to the influence of the input filters on the performance of the STATCOM systems. A detailed analysis of the influences of input filters on the stability of STATCOM systems and the corresponding design considerations are presented in this paper. Three types of input filters, L filters, LC filters, and LCL filters, are examined separately. The influences of the parameters of input filters on system stability are investigated through frequency domain methods. With direct current control taken as the major control strategy for the STATCOMs, the different situations when adopting different current detection points are covered in this analysis. A comparison between LC filters and LCL filters is also presented with optimized filter parameters. Based on the analysis, the phase margin, as one of the design considerations for the different types of input filters under different current detection schemes, is discussed. This leads to filter parameters that are different than those of the traditional design. Hardware experimental results verify the validity of the above analysis and design.

• 한국철도학회논문집
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• 제11권2호
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• pp.151-157
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• 2008

디젤엔진 배기가스 저감 장치의 세라믹 필터 재생 특성을 파악하는데 있어서 중요한 인자인 세라믹 필터 내의 온도 분포를 30군데에서 측정하였다. 세라믹 필터 내의 온도 분포에 적합하도록 제작한 K-형 열전대를 사용하여 측정하였다. 5개로 구성된 분할형 전기히터를 장착하고 중심부 전기히터부터 차례로 돌아가면서 ON/OFF 제어를 하면서 세라믹 필터 내의 온도를 측정하였다. 또한 공기 공급 유량을 변화 시키면서 분할형 전기히터의 ON/OFF 제어가 세라믹 필터 내의 온도 분포 특성에 미치는 영향을 연구하였다. 세라믹 필터 내의 온도가 균일한 분포를 가지려면 배기가스저감 장치 입구에서의 유속 분포가 균일한 경우가 유리하였다. 분할형 히터간의 가열 능력 편차에 의해 세라믹 필터 내의 온도 분포도 큰 영향을 받았다.

• 대한전자공학회논문지SP
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• 제38권4호
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• pp.401-410
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• 2001

MMMF(Modified 2D Multi-shell Median Filter)를 기초로 하여 가변 문턱 조건과 홀/짝수 다중셀을 이용한 Adaptive Odd/Even MMF(Multi-shell Median Filter)를 제안하였다. 제안된 알고리즘은 MATLAB을 이용하여 연구하고 테스트하였다. 제안된 알고리즘의 성능은 이미 잘 알려진 이미지에 임펄스 노이즈(Impulse Noise)와 Line Missing을 적용하여 평가하였고 이를 FPGA로 구현하였다. 제안된 가변 문턱 조건은 연산 시간과 불필요한 재배치를 줄였고, 홀수 셀과 짝수 셀은 각각 십자 방향과 대각선 방향의 Line Missing을 복구하였다. 특히 짧은 연산 시간으로 실시간을 요구하는 이미지 처리 분야에서 효과적으로 이용할 수 있다.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.899-910
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• 2013

This paper presents a novel lateral stability control system for electric vehicle based on sideslip angle estimation through Kalman filter using the integration of a single antenna GPS receiver and yaw rate sensor. Using multi-rate measurements including yaw rate and course angle, time-varying parameters disappear from the measurement equation of the proposed Kalman filter. Accurate sideslip angle estimation is achieved by treating the combination of model uncertainties and external disturbances as extended states. Active front steering and direct yaw moment are integrated to manipulate sideslip angle and yaw rate of the vehicle. Instead of decoupling control design method, a new control scheme, "two-input two-output controller", is proposed. The extended states are utilized for disturbance rejection that improves the robustness of lateral stability control system. The effectiveness of the proposed methods is verified by computer simulations and experiments.

• 전자공학회논문지T
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• 제36T권4호
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• pp.53-59
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• 1999

본 논문에서는 전력용 능동필터의 성능을 가지는 양방향성 무정전 전원장치를 제안한다. 제안된 시스템은 전력용 능동필터모드와 배터리 방전전력모드인 2가지 모드로 나누어진다. 전력용 능동필터모드에서 고조파전류와 무효전력을 효과적으로 보상하기 위하여 기준전류를 계산하는데, 새로운 폐-루프 제어기법이 사용된다. 마지막으로, 제안된 무정전 전원장치의 성능이 시뮬레이션과 실험에 의해 검증된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.553-558
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• 2002

The harmonics in railway high voltage system is due to common use of 3 phase incoming bus and doing the power converter for traction system on the electric car(or electric locomotive). This paper, we analyze the harmonics mechanism and characteristics of railway high voltage system, also we analyze the problem according to the actual measurement about influence of harmonicsontherailwayhighvoltagesystem. And we proved the countermeasure device(passive filter or L-C filter) of harmonics applies in the field. The test result, we have know that the filter is not fit. Consequently, The countermeasure of harmonics for the railway high voltage system be able to resolve by another filter.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권5호
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• pp.326-332
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• 1999

In this paper, we designed and fabricated High-Tc Superconducting (HTS) microstrip bandpass filters using Stepped Impedance Resonators(SIR) and studied on their characteristics. The $high-T_c$ superconducting $Y_1Ba_2Cu_3O_{7-x}$ epitaxial films were deposited by Pulse Laser Deposition (PLD) system on MgO. The fabricated filters were designed so as to operate in Ku band with central frequency 17.25 GHz, bandwidth 2.896% and ripple 0.01 dB. These filters were composed of parallel coupled microstrip SIR of which impedance ratio (K) are 0.5, 1.5. In the measured response, HTS filters had showed insertion loss below -0.5 dB. For comparison with normal conducting filter, we fabricated the Au counterpart that consists of the resonators as K=1.5 in the same dimension and measured performance of the Au filter. In comparison, HTS filter designed optimally got superior response to gold conterpart.

• Journal of Power Electronics
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• 제19권5호
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• pp.1303-1314
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• 2019

This paper studies the harmonic characteristics of ship electric propulsion systems and their treatment methods. It also adopts effective measures to suppress and prevent ship power systems from affecting ship operation due to the serious damage caused by harmonics. Firstly, the harmonic characteristics of a ship electric propulsion system are reviewed and discussed. Secondly, aiming at problems such as resonant frequency and filter characteristics variations, resonance point migration, and unstable filtering performances in conventional passive filters, a method for fully tuning of a passive dynamic tunable filter (PDTF) is proposed to realize harmonic suppression. Thirdly, to address the problems of the uncontrollable inductance L of traditional air gap iron core reactors and the harmonics of power electronic impedance converters (PEICs), this paper proposes an electromagnetic coupling reactor with impedance transformation and harmonic suppression characteristics (ECRITHS), with the internal filter (IF) designed to suppress the harmonics generated by PEICs. The ECRITHS is characterized by both harmonic suppression and impedance change. Fourthly, the ECRITHS is investigated. This investigation includes the harmonic suppression characteristics and impedance transformation characteristics of the ECRITHS at the fundamental frequency, which shows the good performance of the ECRITHS. Simulation and experimental evaluations of the PDTF are carried out. Multiple PDTFs can be configured to realize multi-order simultaneous dynamic filtering, and can effectively eliminate the current harmonics of ship electric propulsion systems. This is done to reduce the total harmonic distortion (THD) of the supply currents to well below the 5% limit imposed by the IEEE-519 standard. The PDTF also can eliminate harmonic currents in different geographic places by using a low voltage distribution system. Finally, a detailed discussion is presented, with challenges and future implications discussed. The research results are intended to effectively eliminate the harmonics of ship electric power propulsion systems and to improve the power quality of ship power systems. This is of theoretical and practical significance for improving the power quality and power savings of ship power systems.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2062-2069
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• 2015

In the series hybrid active power filter (SHAPF) with magnetic flux compensation (MFC), the system current oscillate in the experimental results when adding the same phase harmonic current command in current control block. This condition endangers the security of the SHAPF. Taking the digit period average arithmetic as example, this paper explains the inter-harmonics current oscillation in the experiment. The conclusion is that the SHAPF is unstable to the inter-harmonics current in theory. Limited by the capacity of the inverter, the system current and the inverter output current do not increase to infinite. At last, some methods are proposed to solve this problem. From the practical viewpoint, the voltage feed-forward control is easy to achieve. It can suppress the current oscillation problems, and also improve the filtering effect. The feasibility of the methods is validated by both the emulation and experiment results.

• 제어로봇시스템학회논문지
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• 제22권7호
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• pp.562-569
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• 2016

This paper proposes a navigation system with a robust localization method for an underwater unmanned vehicle. For robust localization with IMU (Inertial Measurement Unit), a DVL (Doppler Velocity Log), and depth sensors, the EKF (Extended Kalman Filter) has been utilized to fuse multiple nonlinear data. Note that the GPS (Global Positioning System), which can obtain the absolute coordinates of the vehicle, cannot be used in the water. Additionally, the DVL has been used for measuring the relative velocity of the underwater vehicle. The DVL sensor measures the velocity of an object by using Doppler effects, which cause sound frequency changes from the relative velocity between a sound source and an observer. When the vehicle is moving, the motion trajectory to a target position can be recorded by the sensors attached to the vehicle. The performance of the proposed navigation system has been verified through real experiments in which an underwater unmanned vehicle reached a target position by using an IMU as a primary sensor and a DVL as the secondary sensor.