• 대한전자공학회논문지
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• 제20권4호
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• pp.41-46
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• 1983

The current-fed DC-DC converter has only one energy storage reactor in series with the input for any number of outputs and is insensitive to transformer volt-second unbalance. It is considered that these properties of the converter are considerable advantages over other maltiple-output circuits. The steady-state and dynamic characteristic and stability for the current-fed DC-DC con-verter are analyzed in detail. The analysis is carried out by the state-space averaging method for the operation with the duty ratio less than 50% and is confirmed by the experiment. From the evaluation of stability it is identified that the stability of this converter is excellent as compared with that of the conventional buck type converter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.41-43
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• 1993

This paper is proposed a method that optimizes teeth shape of Linear induction motor for high efficiency and slot shape for static end effect minimization in linear induction motor. As a result, unbalance current of each phase in minimized.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.466-467
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• 2010

Researches about DSTATCOM are mainly divided two parts, one is the calculation of the load-side average active power and dc-link capacitor average voltage, the other part is the current control. This paper proposes a calculation of dc-link capacitor average voltage using improved method instead of conventional method using LPF (low pass filter). Through the theoretical analysis and simulation under unbalance loads and non-linear load, the proposed method is verified.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.375-376
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• 2020

계통의 전류 불평형은 고장 또는 단상 부하에 의해 발생한다. 불평형 전류는 계통의 손실을 증대시키고, 전압 불평형으로 나타날 수 있어 계통의 안정성 문제로 이어진다. 본 논문은 계통 연계형 PCS를 통해 계통 불평형 전류를 보상하여 계통의 손실을 낮추고 안정성을 높이는 불평형 전류제어 알고리즘을 제안한다. 제안한 방법은 시뮬레이션을 통해 검증한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.493-497
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• 2000

A battery is the device that transforms the chemical energy into the direct-current electrical energy without a mechanical process. Unit cells are connected in series to obtain the required voltage while being connected in parallel to organize capacity for load current. Because the voltage drop down in one set of battery is faster than in two one it may result in the low efficiency of power converter with the voltage drop and cause the system shutdown. However when the system being shutdown. However when the system being driven in parallel a circular-current can be generated,. It is shown that as a result the new batteries are heated by over-charge and over-discharge and the over charge current increases rust of the positive grid and consequently shortens the lifetime of the new batteries. The difference between the new batteries and old ones is the amount of internal resistance. In this paper we can detect the unbalance current using the microprocessor and achieve the balance current by adjusting resistance of each set, The internal resistance of each set becomes constant and the current of charge and discharge comes to be balanced by inserting the external resistance into the system and calculating the change of internal resistance.

• 대한전기학회논문지:전력기술부문A
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• 제51권10호
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• pp.510-517
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• 2002

The use of underground transmission cables has continuously increased in densely inhabited urban and suburban area. Due to a increasing demand of underground cables, two or more circuits are installed in parallel for several kilometers. It, however, has not been realized that the sheath circulating current is generated in the system where a large number of cables are laid in the same route. In this paper, sheath circulating current is analyzed by the EMTP and compared with the measured values. Unbalance arrangement of cables or cross-bonding length causes a significant effect on the magnitude of the sheath current. Sheath circulating current could be greatly reduced by the symmetrical configuration of cables and installation of the impedance reduction system. Especially, with the impedance system of 1Ω installed, the sheath circulating current is reduced by 85.7%.

• 전력전자학회논문지
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• 제21권6호
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• pp.473-480
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• 2016

This study proposes a performance improvement for parallel-connected thyristor dual converters using a circulating current with an unbalanced parallel operation compensator. The proposed control method determines a variable reference value for the voltage PI controller according to voltage error at firing angle control applied to a difference current control. This method uses circulating current control to maintain a stable voltage and excellent current response during parallel operation. The effectiveness of the proposed control is verified with a simulation and an experiment based on the comparison of the performance of the proposed control method with other conventional methods.

• Journal of Power Electronics
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• 제8권1호
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• pp.10-22
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• 2008

The wind-driven doubly fed induction generator (DFIG) is currently under pressure to be more grid-compatible. The main concern is the fault ride-through (FRT) requirement to keep the generator connected to the grid during faults. In response to this, the paper introduces a novel model and new control scheme for the DFIG. The model provides a means of direct stator power control and considers the stator transients. On the basis of the derived model, a robust linear quadratic (LQ) controller is synthesized. The control law has proportional and integral actions and takes account of one sample delay in the input owing to the microprocessor's execution time. Further, the influence of the grid voltage imperfection is mitigated using frequency shaped cost functional method. Compensation of the rotor current pulsations is proposed to improve the FRT capability as well as the generator performance under grid voltage unbalance. As a consequence, the control system can achieve i) fast direct power control without instability risk, ii) alleviation of the problems associated with the DFIG operation under unbalanced grid voltage, and iii) high probability of successful grid FRT. The effectiveness of the proposed solution is confirmed through simulation studies on 2MW DFIG.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.98-103
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• 2009

In this paper, we test the electrical resistance of flat wire in the PV module. normally solar cell has two kind of flat wire(inter connection ribbon and bus bar ribbon). we found the phenomenon that has a unbalance with resistance when we make a wiling between of string. So, we measurement the resistance of flat wire each other. and analysis of missmatch with resistance between flat wires on PV module. next to survey of IR picture on missmatch flat wire samples for analyze of missmatch with current in the wire. and we perform IR test with solar cell that has a connection with flat wire for test the effect of missmatch resistance on solar cell. Finally we perform the Dark I-V test for survey of effect by the unbalance of resistance. By the result of Dark I-V test, the series resistance of existing connection sample is large more then innovated connection sample.

• 전력전자학회논문지
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• 제10권4호
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• pp.373-379
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• 2005

본 논문에서는 인버터를 구동하는 용도의 직류전원장치에 대한 제어 알고리즘 개발을 목표로 하고 있으며, 구동과 회생기능을 갖는 전압형 PWM 컨버터에서 운전시 전원의 불평형을 보상하는 제어방법을 제안한다. 교류전원에 대하여 컨버터가 항상 평형상태를 유지하는 방법은 전류제어 루프에 의하여 불평형 상태를 보상하는 방법을 사용하였으며, 불평형의 제어는 전력변환기의 구성면에 있어서 각상의 리액턴스가 같지 않은 누설변압기 등의 사용을 가능하게 하므로 제안된 전력변환기의 하드웨어와 제어 알고리즘은 장치의 소형화와 효율향상에 기여할 것이다.