• Journal of Power Electronics
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• v.18 no.1
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• pp.34-44
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• 2018

This paper presents a pulse-width adjustment (PWA) strategy for a novel bidirectional DC-DC boost converter to improve the performance of the dynamic inductor current response. This novel converter consists of three main components: a full-bridge converter (FBC), a high-frequency isolated transformer with large leakage inductance, and a three-level voltage-doubler rectifier (VDR). A number of scholars have analyzed the principles, such as the soft-switching performance and high-efficiency characteristic, of this converter based on pulse-width modulation plus phase-shift (PPS) control. It turns out that this converter is suitable for energy storage applications and exhibits good performance. However, the dynamic inductor current response processes of control variable adjustment is not analyzed in this converter. In fact, dc component may occur in the inductor current during its dynamic response process, which can influence the stability and reliability of the converter system. The dynamic responses under different operating modes of a conventional feedforward control are discussed in this paper. And a PWA strategy is proposed to enhance the dynamic inductor current response performance of the converter. This paper gives a detailed design and implementation of the PWA strategy. The proposed strategy is verified through a series of simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.440-447
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• 2011

This paper deals with supercapacitor energy storage system for the compensation of the slow response characteristics of a fuel cell generation system for grid connection. A bidirectional dc/dc converter is used for the charging and discharging of the supercapacitor. The conventional converters use additional clamping circuit, etc. to reduce a voltage spike at the instant of switching and to provide wide range of soft switching. The proposed method provides simplified hardware implementation without any clamping circuit, and soft switching condition for both charging and discharging mode with proper switching patterns. The usefulness of the proposed scheme is verified through simulation and experimental results with 1 kW system.

• Journal of Power Electronics
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• v.15 no.1
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• pp.18-30
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• 2015

This paper focuses on a systematical and in-depth analysis of the reactive power and soft-switching regions of Dual Active Bridge (DAB) converters with dual-phase-shift (DPS) control to achieve high efficiency in a wide operating range. The key features of the DPS operating modes are characterized and verified by analytical calculation and experimental tests. The mathematical expressions of the reactive power are derived and the reductions of the reactive power are illustrated with respect to a wide range of output power and voltage conversion ratios. The ZVS soft-switching boundary of the DPS is presented and one more leg with ZVS capability is achieved compared with the CPS control. With the selection of the optimal operating mode, the optimal phase-shift pair is determined by performance indices, which include the minimum peak or rms inductor current. All of the theoretical analysis and optimizations are verified by experimental tests. The experimental results with the DPS demonstrate the efficiency improvement for different load conditions and voltage conversion ratios.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.103-104
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• 2012

In the AC module system, mismatch problem between AC power and constant input power is occurred. To solve this problem, electrolytic capacitor is utilized for diminishing power pulsation in PV side. However, it has disadvantages of low life span and weak in temperature. Decoupling method has been studied to reduce the capacitance and replaces electrolytic capacitor to film capacitor. This paper proposes design method for decoupling circuit which bidirectional DC-DC converter using soft switching. Proposed system is verified by design optimization and simulation results.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.184-185
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• 2013

In this paper, design of a variable inductor using MR Fluid Gap is proposed for wide load range efficiency improvement of a bidirectional DC-DC converter. As compared to conventional constant value inductor designed to have negative current for ZVS at heavy load but suffers high losses at light load due to its small inductance, the proposed variable inductor not only have small inductance at high current for ZVS but also it has large inductance at low current to decrease light load losses.

• 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.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.95-100
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• 2022

In this paper, a power loss analysis technique of a high-frequency transformer of a bidirectional DAB (Dual Active Bridge) converter is reported. To miniaturize the transformer of the dual active bridge converter, a resonant inductor was designed with an air gap included low-coupled rate state core to combine leakage inductor with the resonant inductor which is required for soft-switching. In this paper, leakage inductance and magnetizing inductance, core material, type of winding and winding method are included in the dual active bridge transformer loss analysis process to enable optimal design at the initial design stage. Transformer loss analysis for dual active bridge with a switching frequency of 200 kHz and maximum output of 5 kW was executed, and elements necessary for design based on the number of turns on the primary side were graphed while maintaining the transformer turns ratio and window area. In particular, it was possible to determine the optimal number of turns and thickness of the transformer, and ultimately, the total loss of the transformer could be estimated.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.431-432
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• 2012

The proposed dc-dc convertor for a battery energy storage system(BESS) can reduce the power rating and bidirectional power flow. This system consist soft-switching bidirectional dc-dc converter so it can reduce the energy loss when charging and discharging mode. Thus it can achieve high efficiency. Also, overall system utilizes the voltage compensation circuit. It is composed of small size and low cost due to reducing the power rating. In this paper, we proposed system about verified by simulation.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.211-212
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• 2016

본 논문에서는 비절연 고승압 소프트 스위칭 양방향 DC-DC 컨버터의 PWM Plus Phase Shift(PPS) 제어기법을 제안한다. 제안하는 컨버터는 기존의 하프브리지 양방향 컨버터의 2배의 승 강압비를 가지며 CCM에서 모든 스위치가 소프트스위칭을 성취한다. 또한, PPS 제어기법을 적용하여 스위치의 전압/전류정격을 최소화할 뿐 아니라 매끄러운 모드전환이 가능하다. 제안하는 양방향 컨버터의 3kW 시작품은 5.2배의 승 강압동작에서 최고효율 97.2%, 97.5%를 달성하였다.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.143-144
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• 2013

본 논문에서는 전기자동차 배터리 충방전용 3상 인터리브드 양방향 DC-DC 컨버터의 소프트 스위칭에 대해 다루었다. 양방향 DC-DC 컨버터의 한쪽 단자는 계통과 연결된 PWM 컨버터의 DC-link단과 연결되고, 다른 한쪽 단자는 배터리에 연결된다. 양방향 DC-DC 컨버터의 소프트스위칭에 대해 기술한 다음 인덕터의 권선 저항이 소프트 스위칭 동작에 미치는 영향을 분석하였으며, 시뮬레이션을 통하여 제안한 방식의 타당성을 검증하였다.