• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.195-196
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• 2015

This paper investigates the design of coupled inductor for minimum inductor current ripple in rapid traction battery charger systems. Based on the general circuit model of coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor is derived under the different duty ratio. The optimal coupling factor which corresponds to a minimum inductor ripple current becomes -0.5, i.e. a complete inverse coupling without leakage inductance, as the steady-state duty ratio operating point approaches 1/3 or 2/3. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the steady-state duty ratio operating point approaches either zero or one. Coupled inductors having optimal coupling factor can minimize the ripple current of inductor and battery current resulting in a reliable and efficient operation of battery chargers.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.117-123
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• 2003

This paper deals with pressure ripple and noise reduction characteristics for a hydrostatic transmission(HST) consisting of a variable axial piston pump connected in an open loop to a fixed displacement axial piston motor. Pressure ripples in HST is major source of vibration, which can lead to fatigue failure of components and cause noise. In order to reduce the pressure ripple, an annular tube type hydraulic filter proposes to absorb pressure ripples with the high frequencies components to achieve better noise attenuation in HST. The basic principle tube is applied to propagation of pressure wave, reflection, absorption in cross section of discontinuity and resonance in the hydraulic pipeline. It is experimently confirmed that a hydraulic filter is absorbed to be about 30∼40dB of pressure ripple with high frequencies. These results will assist in modeling and design of noise reduction in hydraulic control systems, and here, should provide a means of designing a quieter HST.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.154-162
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• 2000

A technique to suppress the low frequency ripple voltage of the DC output ${\gamma}$oltage in three-phase buck d diode rectifiers is presented in this paper. The proposed pulse frequency modulation method is employed to r regulate the output voltage of the buck diode rectifiers and guarantee zero-current switching of the switch over the Vvide load range. The pulse frequency control method used in tIns paper shows generally good p performance such as low THD of the input line current and unity power factor. In addition, the pulse f freιluency method can be effectively used to suppress the low frequency voltage ripple appeared in the dc output voltage. The proposed technique illustrates its validity and effectiveness through the respective s simulations and experiments.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.2
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• pp.121-128
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• 2018

This work proposes a simple control method of a buck-type active power decoupling circuit that can minimize the ripple values in the dc link voltage. The proposed method utilizes a simplified duty calculation method and an optimal compensation gain tracking algorithm with variable-step approach. Thus, the dc link voltage ripple can be effectively reduced through the proposed method along with rapid response in tracking the optimum compensation gain. Moreover, the proposed method has better dynamic responses in the load fluctuation or abnormal situation. MATLAB/Simulink simulation and hardware-in-the-loop-simulation(HILS)-based experimental results are presented to validate the effectiveness of the proposed control method.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1122-1130
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• 2016

This paper presents a novel approach for achieving both a tight DC voltage regulation and a power factor control by applying the Reaching Law Sliding Mode Control (RL-SMC) and the conventional Sliding Mode Control (SMC). Applying these strategies on a matrix rectifier (MR) can achieve a unity grid side power factor when the DC load changes widely and it can provide a ripple-free output voltage that is easily affected by distortions of the three-phase ac voltage supply. Furthermore, by employing the reaching law on the SMC can solve the chatting problem of the sliding motion. Comparative Matlab simulations and experimental verifications for these strategies have been presented and discussed in this paper. The results show that by applying the SMC and RL-SMC on a MR can achieve a unity grid side power factor and a regulated ripple-free DC output.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.3
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• pp.11-19
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• 1997

본 논문에서는 스위치드 리럭턴스 전동기의 토크 리플 또는 소음을 감소하기 위한 방법으로써 순시 전압제어방식을 제시하였다. 이 방식은 상 정류의 제곱의 합ㅇ르 제어하여 토크 리플을 제거할 수 있다. 제안방식에 대해 해석하였으며, 이 방식의 이론적인 타당성을 입증시키기 위해 소프트웨어 페키지 ASCL에 의해 시뮬레이션하였다. 실험에 의해 SRM 토크 리플의 제거를 확인하였다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.406-407
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• 2011

The dc link voltage in a single-phase PV system has necessarily twice component of fundamental wave. It makes high THD in the grid current, and according to the problem, power quality is lower. This paper proposes the new method for removing ripple voltage. The performance was verified through computer simulation using MATLAB.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.523-524
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• 2008

Proposed battery charger is a economic candidate because that is simple and small size. The circuit has linearly operational power stage. That use small size buffer with small driving current and large power MOS gate capacitance. The simulation result show that charging current is stable and has low ripple.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1036-1045
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• 2016

This paper presents a novel control strategy for passive output filter reduction using an active output filter. The proposed method achieves the dual-function of regulating the output voltage ripple and output voltage variation during load transients. The novel control strategy allows traditional simple voltage controllers to be used, without requiring the expensive current sensors and complex controllers used in conventional approaches. The proposed method is verified with results from a 125-W forward converter.

• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.106-112
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• 2012

As a fuel cell converts the chemical energy of the fuel cell into electrical energy by electrochemical reaction, the fuel cell system is uniquely integrated technique including fuel processor, fuel cell stack, power conditioning system. The residential fuel cell-PCS(Power Conditioning System) needs to convert efficiently the DC current produced by the fuel cell into AC current using single-phase DC-AC inverter. A single-phase DC-AC inverter has naturally low frequency ripple which is twice frequency of the output current. This low frequency(120Hz) ripple reduces the efficiency of the fuel cell. This paper presents notch filter with IP voltage controller to reject specific 120Hz current ripple in single-phase inverter. The notch filter is designed that suppress just only specific frequency component and no phase delay. Finally, the proposed notch filter design method has been verified with computer simulation and experimentation.