• 조명전기설비학회논문지
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• 제29권2호
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• pp.82-90
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• 2015

This paper proposes an efficient bi-directional DC/DC converter topology using multi-phase interleaved method for power storage system. The proposed converter topology is used for a power storage system using a vanadium redox flow battery(VRFB) and is configured to enable bidirectional power flow for charging and discharging of VRFB. Proposed DC/DC converter of the 4 leg method is reduced to 1/4 times the rating of the reactor and the power semiconductor device so can be reduce the system size. Also, proposed topology is obtained the effect of four times the switching frequency as compared to the conventional converter in each leg with a 90 degree phase shift 4 leg method. This can suppress the reduction of the life of the secondary battery because it is possible to reduce the current ripple in accordance with the charging and discharging of VRFB and may increase the efficiency of the entire system. In this paper, it proposed bidirectional high-efficiency DC/DC converter topology Using multi-phase interleaved method and proved the validity through simulations and experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 학술대회 논문집 전문대학교육위원
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• pp.108-111
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• 2007

A novel voltage sag compensator with hi-directional DC/DC converter of Electric double layer capacitor is proposed. Recently, the double-layer capacitor which is drawn attention as a new energy storage element has a lot of advantage such as no maintenance, long lifetime and quick charge/discharge characteristics with large current. This DC/DC converter is used to control the charging current to the double-layer capacitor and also used to keep the DC link voltage constant for discharge of the double-layer capacitor. Therefore, the proposed DC/DC converter has the high-efficiency controller, dynamic compensator of voltage sag is driven by this converter. Finally, experimental results show the validity of the control scheme and the ability of the dynamic voltage compensator.

• 전력전자학회논문지
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• 제19권2호
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• pp.124-132
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• 2014

In this paper, we implement a non-time-varying transfer function of the duty ratio to improve the control characteristics in a control system that Input voltage and the output voltage is varied, DC / DC converters for bi-directional charging. When control is performed with using controller gain of conventional design, characteristics of the control is varied to fluctuations of the input voltage. The proposed method is the equivalently removing method for duty ratio in entire control block, by voltage controller gain is changed for inverse of the duty ratio. The proposed non-time-varying duty ratio transfer function is applied to DC / DC converter for bi-directional charging. In this paper, feasibility and superiority is verified through PSIM simulations and experiments.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.479-480
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• 2010

In this paper, the bi-directional soft switching DC-DC converter using ZCT(Zero Current Transition) method is proposed for using battery application system. This topology is composed of soft switching bi-directional buck/boost converter having the ZCT auxiliary circuit with two switches, two resonant capacitors, one resonant inductor. Therefore, the proposed topology can reduce switching loss. To verify the validity of the proposed topology, theoretical analysis and simulation results are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.479-483
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• 2004

Fuel Cell (FC) has slow response characteristic for load variation. During a load step, the inverter cannot pull more power from the fuel cell than is currently available so supplemental power must be provide by some sort of energy storage elements. In this paper, hi-directional do-dc converter for FC generation system is proposed to improve load response characteristic. The hi-directional converter interfaces the low voltage battery to the inverter dc link of FC generation system. The converter is based on a active full bridge in the primary side and on a half bridge in the secondary of a high frequency isolation transformer. The complete operating principles and simulation results in presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1023-1025
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• 2001

This paper proposes a bi-directional current switch with snubber regeneration using Power MOSFETs and this paper proposes to use a loss-less snubber with switching device to perform soft-switching. It results in not only decreasing switching loss in the device drastically, but also improving input ac current waveform distortion. The computer simulation results show that the input current waveform and show the requirements necessary for the elimination of the 3rd harmonic component. We also show the procedure to design the parameters of the converter.

• Journal of Power Electronics
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• 제9권4호
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• pp.517-525
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• 2009

42V electrical power systems are on their way to replacing the present l4V systems in automobiles and 42V/14V dual voltage systems have been proposed to provide backward compatibility with the existing components for the 14V systems. A synchronous buck/boost converter is an attractive topology for 42V/14V dual voltage systems since it offers the possibility of bi-directional operation without additional components. In this paper, transient currents generated during converter startup or changes in operation modes between buck and boost are analyzed and a cost effective solution to remove the transient currents is proposed. The validity of the proposed control strategy is investigated through simulation and experiment with bi-directional converters.

• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1634-1644
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• 2016

In this paper, a current-fed two-inductor bi-directional DC/DC converter using resonance (CF-TIBCR) and its design method are proposed. The CF-TIBCR has characteristics of low current ripple and a high current rating because of two separated inductors. Also, it achieves zero voltage switching for all switches and zero current switching for switches of a low voltage stage by using the resonant tank. Besides, a voltage spike problem in conventional current-fed converters is solved without the need for an additional snubber or clamping circuits. As a result, the CF-TIBCR features high step-up and high efficiency. Since the proposed converter has difficulty achieving the soft-switching condition when the converter requires the low voltage transfer ratio, a method that varies the number of resonant cycles is adopted to extend the output voltage range with satisfying the soft-switching condition. The principles of the operation characteristics are presented with a theoretical analysis, and the proposed converter is verified through results of an experiment using a laboratory prototype.

• Journal of Power Electronics
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• 제17권6호
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• pp.1433-1444
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• 2017

A family of non-isolated DC-DC three-port converters (TPCs) that allows for a more flexible power flow among a renewable energy source, an energy storage device and a current-reversible DC bus is introduced. Most of the reported non-isolated topologies in this area consider only a power consuming load. However, for applications such as hybrid-electric vehicle braking systems and DC microgrids, the load power generating capability should also be considered. The proposed three-port family consists of one unidirectional port and two bi-directional ports. Hence, they are well-suited for photovoltaic (PV)-battery-DC bus systems from the power flow viewpoint. Three-port converters are derived by combining different commonly known power converters in an integrated manner while considering the voltage polarity, voltage levels among the ports and the overall voltage conversion ratio. The derived converter topologies are able to allow for seven different modes of operation among the sources and load. A three-port converter which integrates a boost converter with a buck converter is used as a design example. Extensions of these topologies by combining the soft-switching technique with the proposed design example are also presented. Experiment results are given to verify the proposed three-port converter family and its analysis.

• 조명전기설비학회논문지
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• 제28권8호
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• pp.90-97
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• 2014

This paper presents a compensation method of unbalanced phase currents in interleaved bi-directional converters. Phase currents in interleaved bi-directional converter are apt to be unbalanced due to circuit parameter error and switch operation difference. This problem causes the switch element failure and the reduced efficiency of the converter. Therefore, it is necessary that a certain balance control algorithm is provided in interleaved bi-directional converter system. In this paper, a balance control algorithm based on the circular chain control method is proposed. Further, in order to reduce the number of phase current sensors, this paper shows a simple method in which phase currents can be extracted indirectly through a DC-link current sensor in both charging and discharging modes. The validity and the effectiveness of the proposed phase currents balance control algorithm are illustrated through the simulation results.