• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.67-68
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• 2007

The introduction of high brightness LEDs with white light and monochromatic colors have led to a movement towards specialty and general illumination applications. Because drive circuit of illumination LED has an effect on efficiency and life, research about the drive circuit following LED characteristic is needed. This paper proposed a implementation of the stand-alone LED lighting system using battery from photovoltaic power generation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.177-182
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• 2001

Of two photovoltaic systems such as stand-alone type and utility interactive one, the utility interactive systems are so valuable for power peak-cut particularly in summer season. For the maximum power point tracking(MPPT) by which the generated energy can be maximized, many control methods have been reported up to now. To overcome the disadvantages of the conventional ones, a new MPPT algorithm is proposed which can improve both tracking ability and generating efficiency of photovoltaic system without chopper.

• 전력전자학회논문지
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• 제24권5호
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• pp.334-341
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• 2019

This study proposes the control strategy for the seamless mode transfer of indirect current controlled parallel grid-connected inverters. Under the abnormal grid condition, the grid-connected inverter can convert the operation mode from grid-connected to stand-alone mode to supply power to the local load. For a seamless mode transfer, the time delay problems caused by the accumulated control variable error must be solved, and the indirect current control method has been applied as one of the solutions. In this study, the design of control parameters for the proportional-resonant-based triple-loop indirect current controller and the control strategy for the seamless mode transfer of parallel grid-connected inverters are described and analyzed. The validity of the proposed mode transfer method is verified by the PSiM simulation results.

• Journal of Power Electronics
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• 제16권2호
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• pp.675-684
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• 2016

This paper presents a new stand-alone wind-based induction generator system with constant frequency and adjustable output voltage. The proposed generator consists of a six-phase cage-rotor induction machine with two separate three-phase balanced stator windings and a three-phase space vector pulse width modulation inverter that operates as a static synchronous compensator (STATCOM). The first stator winding is fed by the STATCOM and used to excite the machine while the second stator winding is connected to the generator external load. The main frequency of the STATCOM is determined to be constant and equal to the load-requested frequency. The generator output frequency is independent of the load power demand and its prime mover speed because the frequency of the induced emf in the second stator winding is the same as this constant frequency. A sliding mode control (SMC) is developed to regulate the generator output voltage. A second SMC is used to force the zero active power exchanged between the machine and the STATCOM. Some simulation and experimental results are presented to prove the validity and effectiveness of the proposed generator system.

• Journal of Advanced Marine Engineering and Technology
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• 제34권6호
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• pp.906-913
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• 2010

최근 해양 시설물용 복합 발전 시스템 개발에 관한 많은 연구가 수행되고 있다. 일반적으로 해양시설물에 사용되는 독립형 전력 공급 시스템은 날씨에 상당히 많은 영향을 받게 된다. 이러한 전력 공급시스템의 효율성을 높이기 위하여 다양한 스위칭 알고리즘을 이용한 충전 기법이 연구되고 있다. 본 논문에서는 다중 레벨 방식을 적용한 전력 시스템의 충전 방식을 제안하고 실험을 통하여 결과를 제시하였다. 다중 레벨 방식의 충전기법을 시뮬레이션한 장치의 실험 결과와 기존에 사용 중인 전력 공급 시스템의 실험 결과를 비교하여 나타내었다. 그 결과, 다중 레벨 방식의 충전기법을 이용하는 경우에 기상 조건에 따라 충전 전력은 5~11%, 충전 가능 시간은 7~47% 정도 향상되었음을 확인하였다.

• 전력전자학회논문지
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• 제12권1호
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• pp.81-88
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• 2007

본 논문에서는 연료전지를 이용한 가정용 발전 시스템의 계통 연계를 위한 새로운 단상 인버터 시스템을 제안한다. 제안한 인버터는 계통연계 운전과 독립 운전이 모두 가능하고 두 운전사이의 모드전환이 자동으로 이루어지며 전환시 최소의 과도상태를 갖는다. 제안한 제어방식은 정상상태 오차가 거의 없고 양호한 과도상태 응답특성을 가진다. 또한 연산량과 센서수가 적고 구조가 간단하여 저가격의 고정소수점 DSP로도 구현이 가능한 특징이 있다. 제안한 계통연계형 인버터의 제어기에 관하여 기술하고 모의실험 및 실험에 의하여 그 타당성을 입증한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.201-202
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• 2012

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charging mode, constant-current mode, and constant-voltage mode. Each mode is operated according to battery states: voltage, current and State of Charging (SOC). The proposed system is able to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 67A. The optimal discharging algorithm for Vehicle to the Grid (V2G) operation has been adopted to maintain the discharging current of 1C. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system. Experiment waveforms confirm the proposed functionality of the charging system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.380-385
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• 1997

The primary concern in designing any PV system is the determination of its optimum size. It is generally inadequate to use monthly or daily average insolation, and estimated number of continuous no sun days to determine array and battery capacities because the dynamic behavior of PV system and the stochastic nature of solar radiation also significantly influence the required array and storage capacity. Simulation method uses hourly meterological data and hourly load data to simulate the energy flow in a PV system, and predicts the system reliabilities under assumed array and battery sizes. Stand alone system for operating efficiency analysis of Photovoltaics system were discribed in this paper.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.429-430
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• 2011

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology with coupled inductors. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charging mode, constant-current mode, and constant-voltage mode. The pre-charging mode employs the staircase shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is able to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 67A. The optimal discharging algorithm for Vehicle to the Grid (V2G) operation has been adopted to maintain the discharging current of 1C. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.323-324
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• 2013

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charge mode, constant-current mode, and constant-voltage mode. The pre-charge mode employs the stair-case shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is specified to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 78A. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.