• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.132-134
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• 2007

하이브리드 차량 및 전기차량 구동 모터의 권선저항에 의한 손실 및 모터의 크기를 줄이기 위해 고효율, 고승압형 DC-DC 컨버터 사용이 요구된다. 기존의 부스트 컨버터는 기생저항 성분에 의해 고승압이 불가능하여 변압기를 사용하여 승압비를 향상시킨 current-fed push-pull, current-fed full bridge, dual inductor-fed 부스트 컨버터 등으로 변형되어 사용되어 왔다. dual inductor-fed 부스트 컨버터의 경우 동일조건하에서 앞서 기술된 2가지 컨버터보다 2배의 승압비를 얻을 수 있으며 1차측 전류 스트레스가 낮은 장점을 가지고 있어 대전력, 고승압 응용에 적합하다. 하지만 변압기의 누설인덕턴스에 의한 써지성 전류/전압을 제한하기 위한 부가적인 snubber회로의 사용으로 효율을 떨어뜨리게 되는 단점을 가지고 있다. 본 논문에서는 이러한 단점을 보완할 수 있는 새로운 2개의 인덕터와 1개의 변압기를 갖는 DC-DC 컨버터를 제안한다. 제안된 컨버터의 동작원리와 모드해석을 실시하고 최종적으로 400W, 42Vdc (Battery)/400Vdc (Electric Motor) 실험결과를 통해 이를 검증한다.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.74-76
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• 2007

In this paper a maximum power point tracking(MPPT) techniques for power of PV(photovoltaic) systems are presented using boost converter for a connected single phase inverter. On the basic principle of power generation for the PV module, algorithms for maximum power point tracking are described by utilizing a boost converter to adjust the output voltage of the PV module. Based on output power of a boost converter, single phase inverter uses predicted current control to control four IGBT's switch in full bridge. Furthermore a low cost control system for solar energy conversion using the DSP is developed, based on boost converter to adjust the output voltage of the PV module. The effectiveness of the proposed inverter system is confirmed experimentally and by means of simulation. Finally, experimental results confirm the superior performance of the proposed method.

• Journal of Power Electronics
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• v.13 no.3
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• pp.419-428
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• 2013

The modular multilevel cascade converter (MMCC) is a new family of multilevel power converters with modular realization and a cascaded pattern for submodules. The MMCC family can be classified by basic configurations and submodule types. One member of this family, the Hexverter, is configured as Double-Delta Full-Bridge (DDFB). It is a novel multilevel AC/AC converter with direct power conversion and comparatively fewer required components. It is appropriate for connecting two three-phase systems with different frequencies and driving an AC motor directly from a utility grid. This paper presents the dq model of a Hexverter with both of its AC systems by state-space representation, which then simplifies the continuous time-varying model into a periodic discrete time-invariant one. Then a generalized multivariable optimal control strategy for regulating the Hexverter's independent currents is developed. The resulting control structure can be adapted to other MMCCs and is flexible enough to include other control criterion while guaranteeing the original controller performance. The modeling method and control design are verified by simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.1
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• pp.37-43
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• 2020

This study proposes a 7kW low-voltage DC-DC converter (LDC) using a coupled inductor (CI) for heavy hydrogen electric transport vehicles. The LDC uses a phase-shift manner for soft switching. SiC-MOSFET is used to reduce the loss of reverse recovery current through the use of a high switching frequency. LDC is require large transformer and inductor because of large output current. The size of transformer and inductor can be reduced by deviding the transformer and inductor into two pieces each. This work presents the experimental results of the proposed circuit.

• Journal of Sensor Science and Technology
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• v.22 no.5
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• pp.364-368
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• 2013

Vibrational energy harvester based on piezoelectricity has been expected to be the dominant energy harvesting technology due to the advantages of high conversion efficiency, light weight and small size, night operation, etc. Its commercialization is just around the corner but the integration with power management electronics should be solved in advance. In this paper, therefore, fully-integrated design environment for piezoelectric energy harvesting systems is presented to assist co-design with the power management electronics. The proposed design environment is capable of analyzing the energy harvester including the package-induced damping effects and simulating the device and its power management electronics simultaneously. When the developed design environment was applied to the fabricated device, the simulated resonant frequency matched well with the experimental result with a difference of 2.97% only. Also, the complex transient response was completed in short simulation time of 3,001 seconds including the displacement distribution over the device geometry. Furthermore, a full-bridge power management circuit was modeled and simulated with the energy harvester simultaneously. Therefore the proposed, fully-integrated design environment is accurate and fast enough for the contribution on successful commercialization of piezoelectric energy harvester.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.502-507
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• 2006

According to large-sized LCD, the CCFL used in backlight is getting longer and a backlight using one lamp makes a needed brightness by arranging lamp in parallel because of the limit of brightness. In this paper, the inverter to nu the large back-light in 42inch LCD TV using 20 CCFLs was designed to produce the same output on each lamp in any input condition. Supplementing the conventional high-low method driving CCFL, by adopting high-high one, the brightness variation among each lamp sides is improved. Additionally, to improve the brightness variation, the method connecting the lamp and the capacitor in series is used. The proposed system was verified by the experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.1
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• pp.31-40
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• 2014

This paper describes an optimal configuration for multi-central inverters in a medium-voltage (MV) grid, which is suitable for large-scale photovoltaic (PV) power plants. We theoretically analyze a proposed common-mode equivalent model for problems associated with multi-central transformerless-type three-phase full bridge(3-FB) PV inverters employing two-winding MV transformers. We propose a synchronized PWM control strategy to effectively reduce the common-mode voltages that may simultaneously occur. In addition, we propose that the existing 3-FB topology may also have the configuration of a multi-central inverter with a two-winding MV transformer by making a simple circuit modification. Simulation and experimental results of three 350kW PV inverters in a multi-central configuration verify the effectiveness of the proposed synchronization control strategy. The modified transformerless-type 3-FB topology for a multi-central PV inverter configuration is verified using an experimental prototype of a 100kW PV inverter.

• Proceedings of the KIPE Conference
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• 2012.07a
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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.

• 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.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.183-184
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• 2012

본 논문에서는 출력 인덕터 리플과 2차 측 정류기의 공진 전압을 저감할 수 있는 다중 위상천이 풀 브리지 컨버터를 제안한다. 제안된 회로는 총 8개의 스위치가 사용되며, 각 4개의 스위치가 하나의 위상천이 풀 브리지 인버터 부를 구성하는 구조이다. 기존 위상천이 풀 브리지 컨버터의 경우, 진상레그와 지상레그의 위상차이를 조절하여 출력전압을 제어하는데 반해, 제안된 회로는 진상레그와 지상레그의 위상차이 뿐만 아니라 각 풀 브리지 인버터 부의 위상차이를 동시에 조절하여 출력전압을 제어하는 것이 특징이다. 이를 통하여 제안회로는 출력 인덕터 전류 리플 및 2차 측정류기의 공진 전압을 크게 저감시킬 수 있어 고 효율화에 유리하다. 본 논문에서는 제안된 회로의 이론적 해석 및 PSIM 모의실험을 수행하며, 450W급 시작품을 제작하여 제안회로의 타당성을 검증하였다.