• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.134-136
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• 2005

The author present a modified multi-loop algorithm Including feedforward for controlling a 55kW stepdown chopper in the power supply of Maglev The gains of the control algorithm were selected based on pole locations formulated from a prototype Bessel transfer function model. The design incorporate tradeoffs in DC-to-DC converter hard-ware para-meters and pole locations. This perturvation is derived by subtracting the desired output voltage from the actual output voltage. The proportional and integral action stabilizes the system and minimizes output voltage error. In order to verify the validity of the proposed multi-loop controller, simulation study was tried using Matlab simulink.

• 전력전자학회논문지
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• 제23권1호
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• pp.32-39
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• 2018

A new dc link voltage controller for a three-phase Vienna rectifier is proposed in this study. This method uses load current and duty information to control dc link voltage. The load current affects the capacitor current and varies the output voltage. Existing methods do not perfectly consider the load current. By considering load current with duty compensation in the proposed method, the transient response is improved by the load variation regardless of the input voltage. The effectiveness of the proposed method is compared with other control methods when the load changes rapidly using PSIM simulation and experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.850-852
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• 1993

A buck-boost zero current switched(ZCS) series resonant AC to DC converter for the DC output voltage regulation together with high power factor is proposed. A dynamic model for this AC to DC converter is developed and an analysis for the internal operational characteristics is explored. With the proposed control technique, the unity power factor and the DC output voltage regulation without a current overshoot can be obtained.

• Journal of Power Electronics
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• 제15권6호
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• pp.1609-1618
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• 2015

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings' power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1562-1568
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• 2014

Based on the average method and the geometrical technique to calculate the average value, the average model of the open-loop step-up converter in CCM operation is established. The DC equilibrium point and corresponding small signal model is derived. The control-to-output transfer function is presented and analyzed. The theoretical analysis and PSIM simulations shows that the control-to-output transfer function includes not only the DC input voltage and the DC duty cycle, but also the two inductors, the two energy-transferring capacitors, the switching frequency and the load. Finally, the hardware circuit is designed, and the circuit experimental results are given to confirm the effectiveness of theoretical derivations and analysis.

• 한국전자통신학회논문지
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• 제12권4호
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• pp.607-614
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• 2017

본 연구에서는 마이크로 컨트롤러를 기반으로 한 PWM 제어 기술을 통해 스마트폰 무선충전을 위한 강압 컨버터를 설계 및 제작하였다. 전압센서를 이용해 출력전압이 기준전압을 따라가도록 피드백 제어 회로를 제작하였다. 강압 컨버터로 311V를 12V 로 출력하고 DC 전압 12V를 무선으로 연결하여 5V 충전 전압을 출력한다. 실험을 통해 스마트폰 무선 충전용 강압 컨버터의 유효성을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1339-1341
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• 2000

This paper presents a new PWM DC/DC converter with multi-output using single secondary winding, which has two output characteristics of the isolation and non-isolation simultaneously. The proposed converter topology is consisted of the only one switch and single secondary winding. The proposed converter, therefore, has advantages not only low cost but also high power density. Operating principal of the proposed converter topology with conventional ZVT (Zero-Voltage-Transition) is illustrated in detail and the validity of the converter is verified with several interesting simulation results.

• 한국통신학회논문지
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• 제18권10호
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• pp.1590-1597
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• 1993

전력변환 시스템은 양방향의 컨버터가 필요하다. 스위칭 레귤레이터 기술의 분야에 있어 절연형 양방향 컨버터의 특징으로서는 여분의 전력을 전원측으로 반환하는 것에 의하여 리액터에 축적된 에너지에 의한 전압의 상승을 억제할 수 있는 것이 보고되어 있다. 또한 전원 시스템에서 전기적 절연에 대한 절연특성이 요구될때 절연에 대해 가장 적합한 부위는 직류 링크부이다. 직류부에서의 변압기는 높은 반복주파수를 사용하면 소형화 할 수 있는 이 점 이 주어진다. 본 논문은 전력변환 시스템용으로서 전압적분치 제어방식에 의해 절연형 양방향 DC-DC 컨버터를 제안한다. 적분치 제어를 이용하면 시스템 구성이 간단하고, 제어오차가 적으며 빠른 출력응답을 얻을 수 있다.

• Journal of Power Electronics
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• 제13권5호
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• pp.766-778
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• 2013

The depletion of natural resources and renewable energy sources, such as photovoltaic (PV) energy, has been highlighted for global energy solution. The PV power control unit in the PV power-generation technology requires a high step-up DC-DC converter. The conventional step-up DC-DC converter has low efficiency and limited step-up ratio. To overcome these problems, a novel high step-up DC-DC converter using an isolated switched capacitor cell is proposed. The step-up converter uses the proposed transformer and employs the switched-capacitor cell to enable integration with the boost inductor. The output of the boost converter and isolated switched-capacitor cell are connected in series to obtain high step-up with low turn-on ratio. A hardware prototype with 30 V to 40 V input voltage and 340 V output voltage is implemented to verify the performance of the proposed converter. As an extended version, another novel high step-up isolated switched-capacitor single-ended DC-DC converter integrated with a tapped-inductor (TI) boost converter is proposed. The TI boost converter and isolated-switched-capacitor outputs are connected in series to achieve high step-up. All magnetic components are integrated in a single magnetic core to lower costs. A prototype hardware with 20 V to 40 V input voltage, 340 V output voltage, and 100 W output power is implemented to verify the performance of the proposed converter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1056-1057
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• 2015

A common DC bus is a useful connection for several DC output sources such as photovoltaic (PV), fuel cells, and batteries. Operation of the common DC power system with more than two DC output sources, especially in a stand-alone mode, requires a control scheme for the stable operation of the system. In this paper, a control scheme has been developed for applying DC power sources to the distribution system. The purpose of the control scheme is to make the best use of the DC power sources. The DC power system consists of PV, two energy storage systems and a DC-AC inverter with the control scheme. A distribution system was modeled in PSCAD/EMTDC. As the results, the control scheme is applied to the DC-AC inverter and the DC-DC converter for transfer operations between the grid-connected and the stand-alone mode to keep the DC bus and the AC voltage constant. The results from the simulation demonstrate the stable operation of a grid connected DC power system.