• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.117-118
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• 2015

본 연구에서는 독립형 직류 배전망 구성에 이용될 수 있는 태양광 발전 시스템 및 ESS(Energy Storage System)를 이용한 하이브리드형 분산 전원 시스템의 구성 일례를 제시한다. 제안된 시스템의 전력회로는 태양광 발전 시스템용 PCS에는 직렬 공진 탱크를 가지는 절연형 풀브리지 방식, ESS용 PCS에는 비절연형 양방향 컨버터로 구성되었다. 태양광 PCS의 제어방식으로는 전류 제어기가 사용되었으며, ESS 용 PCS에는 비집중식 제어방식이 적용 되었다. 제안된 방식의 타당성을 검증하기 위해 100[kW]급 태양광 시스템, 100[kW]급 ESS를 기반으로 하이브리드 시스템을 구현하고 직류 계통 전압 제어 특성, 부하급변에 대한 전력분담 제어 실험결과를 제시하였다.

• Journal of IKEEE
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• v.27 no.4
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• pp.450-455
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• 2023

Among single-phase photovoltaic inverters that can avoid excessive leakage current caused by the large parasitic capacitance of photovoltaic panels, a boost converter followed by a half-bridge inverter is the simplest and has the smallest leakage current. However, due to the high DC-link voltage, the rated voltage of the switching devices is high and the switching loss is large. This paper proposes a new circuit topology which can operate as a buck-boost inverter by adding two bidirectional switches to the output side of the half-bridge inverter instead of removing the boost converter. By reducing two stages of power conversion through the high-voltage DC-link to one stage, power loss can be reduced without increasing costs and leakage current. The feasibility of the proposed circuit topology is verified by computer simulation and power loss calculation.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.335-342
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• 2016

This paper proposes an energy storage-assisted, series-connected module-integrated power conversion system that integrates a photovoltaic power conditioner and a charge balancing circuit. In conventional methods, a photovoltaic power conditioner and a cell-balancing circuit are needed for photovoltaic systems with energy storage devices, but they cause a complex configuration and high cost. Moreover, an imbalanced output voltage of the module-integrated converter for PV panels can be a result of partial shading. Partial shading can lead to the fault condition of the boost converter in shaded modules and high voltage stresses on the devices in other modules. To overcome these problems, a bidirectional buck-boost converter with an integrated magnetic device operating for a charge-balancing circuit is proposed. The proposed circuit has multiple secondary rectifiers with inductors sharing a single magnetic core, which works as an inductor for the main bidirectional charger/discharger of the energy storage. The secondary rectifiers operate as a cell-balancing circuit for both energy storage and the series-connected multiple outputs of the module-integrated converter. The operating principle of the cell-balancing power conversion circuit and the power stage design are presented and validated by PSIM simulation for analysis. A hardware prototype with equivalent photovoltaic modules is implemented for verification. The results verify that the modularized photovoltaic power conversion system in the output series with an energy storage successfully works with the proposed low-cost bidirectional buck-boost converter comprising a single magnetic device.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.379-380
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• 2012

A bidirectional full-bridge CLLC resonant converter using a digital control method is proposed for a LVDC power distribution system. This converter can operate under high power conversion efficiency since the CLLC resonant network has soft switching capability for primary switches and output rectifiers. In addition, the power conversion efficiency of any directions is exactly the same as each other because of the symmetric structure of the converter. Intelligent digital control methods are proposed to regulate output voltage under any power flow directions. A 5kW prototype converter was designed for a high-frequency galvanic isolation of 380V dc buses using a digital signal processor to verify the performance of the proposed topology and algorithms.