• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.444-446
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• 2011

A bidirectional dual active converter with the power factor control capability is proposed as a battery charger. The source side half-bridge acts as a PWM converter that maintains the unity power factor. The battery side half-bridge converter acts as a dual active bridge (DAB) together shares the same DC link voltage with PWM converter. The imbalance voltage phenomenon is eliminated by employing asymmetric duty cycle technique. Simulation results are included to verify theoretical analysis.

• Journal of Power Electronics
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• v.18 no.1
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• pp.45-55
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• 2018

It is usually difficult for dual-active-bridge (DAB) dc-dc converters to operate efficiently at light loads. This paper presents an in-depth analysis of a DAB with triple-phase-shift (TPS) control under the light load condition to overcome this problem. A kind of operating mode which is suitable for light load operation is analyzed in this paper. First, an analysis of the zero-voltage-switching (ZVS) constraints for the DAB converter has been carried out and a reasonable dead-band setting method has been proposed. Secondly, the basic operating characteristics of the converter are analyzed. Third, under the condition of satisfying the ZVS constraints, both the reactive power and the root mean square (RMS) value of the current are simultaneously minimized and a particle swarm optimization (PSO) algorithm is employed to analyze and solve this optimization problem. Lastly, both simulations and experiments are carried out to verify the effectiveness of the proposed method. The experimental results show that the converter can effectively achieve ZVS and improved efficiency.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.6-7
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• 2019

본 논문에서는 양방향 전력 전송을 가능케 해주는 Dual-active-bridge (DAB) 컨버터에서, 고주파 변압기 대신 무선 전력 전송 코일을 이용한 시스템을 제안한다. 기존의 DAB 컨버터에서 주로 사용되는 고주파 변압기는 Core-type 또는 shell-type으로 만들어지며, 1차 측 권선과 2차 측 권선이 자기적으로 강하게 결합되어 높은 전력 전달 효율을 가지도록 만든다. 이런 DAB 컨버터를 직/병렬 연결해 MV-DC to LV-DC로 변환하는 반도체 변압기 등을 구성할 때, 1차 측 권선과 2차 측 권선 사이에는 절연 문제와 1차 측 스위치 회로와 2차 측 스위치 회로, 그리고 고주파 변압기가 각각 따로 절연해야 하는 문제점이 있다. 본 논문에서 제안하는 DAB 컨버터는 1차 측과 2차 측이 수 cm 이격되어 있어 1차 측과 2차 측 사이의 자기적 결합이 굉장히 약하다. 따라서 1차 측과 2차 측 코일을 커패시터로 공진시켜 전력을 전달하는 무선전력전송(Loosely Coupled Inductive Wireless Power Transfer)을 이용한다. 무선전력전송의 공진 topology는 Parallel-Series로 선택했고, impedance transformation 회로를 추가했다.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.199-200
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• 2016

Multi-level Dual Active Bridge (ML-DAB) 컨버터는 높은 스위칭 패턴 자유도를 가져 인덕터 전류의 첨두치와 RMS를 효과적으로 감소시킬 수 있다. 본 논문에서 3-레벨 NPC DAB 컨버터의 동작원리를 분석하고, 비대칭적인 스위칭 패턴을 적용시켜 인덕터 전류의 첨두치를 수학적으로 분석하여 컨버터의 전력변환 효율을 높일 수 있는 동작점 설계 방법을 제안한다. 여러 동작점에 따른 전류 RMS 값을 비교하여 제안하는 동작점 설계 방법의 타당성을 검증하고자한다.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1650-1660
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• 2016

This paper proposes a compensator to eliminate the DC bias of inductor current. This method utilizes an average-current sensing technique to detect the DC bias of inductor current. A small signal model of the DC bias compensation loop is derived. It is shown that the DC bias has a one-pole relationship with the duty cycle of the left side leading lag. By considering the pole produced by the dual active bridge (DAB) converter and the pole produced by the average-current sensing module, a one-pole-one-zero digital compensation method is given. By using this method, the DC bias is eliminated, and the stability of the compensation loop is ensured. The performance of the proposed compensator is verified with a 1.2-kW DAB converter prototype.

• Journal of Power Electronics
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• v.18 no.1
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• pp.137-146
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• 2018

This paper describes a single pulse-width modulation control strategy using the Single Pulse-Width Modulation (SPWM) method with a soft-switching technique for a wide range of output voltages from a bidirectional Dual-Active Bridge (DAB) converter. This method selects two typical inductor current waveforms for soft-switching, and proposes a rule that makes it possible to achieve soft-switching without any compensation algorithm from the waveforms. In addition, both the step-up and step-down conditions are analyzed. This paper verifies that the leakage inductance is independent from the rule, which makes it easier to apply in DAB converters. An integrated algorithm, which includes step-up and step-down techniques, is proposed. The results of experiments conducted on a 50-kW prototype are presented. The system efficiency is experimentally verified to be from 85.6% to 97.5% over the entire range.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.197-198
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• 2014

본 논문에서는 양방향 DC-DC Dual Active Bridge (DAB) 컨버터의 수학적 모델로부터 컨버터의 변압기와 결합 인덕터의 최적 설계 방법을 제안한다. DAB컨버터는 1차 측과 2차 측이 동일한 구조를 가진 고효율 절연형 컨버터로써, Soft Switching이 쉽게 구현되고, 양방향으로 Power를 전달 할 수 있는 장점으로 널리 사용되고 있다. 본 논문에서 제안하는 컨버터는 Solid State Transformer (SST) 용으로 변압기 1차 측과 2차 측의 턴 비가 동일한 구조로써, 최대의 ZVS영역을 확보하고, 전력 변환 효율을 극대화 할 수 있다. 3.3 kW급 시제품을 제작하여 제안하는 컨버터의 타당성을 검증하고자 한다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.556-557
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• 2014

This paper presents an artificial intelligence - Deep Belief Network (DBN) gain-scheduling adaptive PI controller scheme for dual active bridge (DAB) converter. The PI gains are allowed to vary within a predetermined range and therefore eliminate the problems faced by the conventional PI controller. The performance of the proposed controller is simulated and compared with the conventional fixed PI controller under various conditions. The experimental prototype of the DAB converter is implemented using a digital signal processor of TMS320F28335 manufactured by Texas Instrument to examine and to evaluate the performance criteria of the proposed controller. Simulation and experimental results show improvements in transient as well as steady state responses of the proposed controller over the conventional fixed PI controller.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.44-52
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• 2017

This paper describes a 100 kW high-efficiency isolated DC-DC converter for DC distribution system. The DC-DC converter consists of two dual-active-bridge (DAB) converters in parallel. The operating principle of the DAB converter is explained, and the algorithm for parallel operation of the DAB converters is proposed. Simulation and experiments are conducted to verify the performance of the proposed system. Experimental results demonstrate that the developed converter excellently marks 97.4 percent of peak efficiency under its normal operating condition.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.150-158
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• 2017

This study proposes a new pulse-width modulation switching pattern for the low conduction loss of a three-level neutral point clamped (NPC)-based dual-active bridge (DAB) converter. The operational principle for a bidirectional power conversion is a phase-shift modulation. The conventional switching method of the three-level NPC-based DAB converter shows a symmetric switching pattern. This method has a disadvantage of high root-mean-square (RMS) value of the coupling inductor current, which leads to high conduction loss. The proposed switching method shows an asymmetrical pattern, which can reduce the RMS value of the inductor current with lower conduction loss than that of the conventional method. The performance of the proposed asymmetrical switching method is theoretically analyzed and practically verified using simulation and experiment.