• Journal of Power Electronics
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• v.19 no.6
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• pp.1393-1402
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• 2019

This paper proposes a new power flow control method for soft-switched, four channel, five level resonant buck dc-dc converters. These converters have two input channels, which can be supplied from sources with identical or different voltages, and four output channels with arbitrary output voltages. They are specially designed to supply multilevel inverters. The design methodology for their power flow control has been developed considering a general case when the input voltages, output voltages and loads can be asymmetrical. A special emphasize is paid to the limitations and restrictions of operation. The theoretical studies are confirmed by numerical simulations and laboratory tests carried out at various operation points. Exploiting the advantages of the newly proposed power control strategy, the converter can supply five level inverters in dc microgrids, active filters, power factor correctors and electric drives. They can also play an interfacing role in renewable energy systems.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.5
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• pp.923-930
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• 2020

In modern society, various DC power supplies are required to operate the system circuits of various electric devices. A stable DC supply is essential for the normal operation of the circuit and the importance of the converter for this is very high. This study proposed a PWM DC-DC converter circuit that applied a 3-pole 2-zero voltage controller to a KY converter, a step-up DC-DC converter, to maintain a stable supply of output voltage regardless of load fluctuations. In order to prove the normal operation characteristics of the proposed converter circuit, a PSIM simulation and a circuit operation experiment on the PCB board were performed in comparison with the conventional converter circuit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.55-64
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• 2007

This paper represents characteristics and design example of series loaded LCC type high frequency resonant DC-DC converter with variable parallel capacitor in the secondary side of inductive power transformer. In this converter, ZVS(zero voltage switching) technique is applied to reduce turn-off switching losses, and the applied converter used the PFM switching pattern to control output voltage. The operating characteristics of the proposed converter is analyzed using nomalized parameter such as switching frequency and load factor with varing the secondary parallel resonant capacitor. The results of analysis show the operating characteristics and design method of the proposed converter using characteristic values. And the proposed converter can be applied for the contactless power supply with linear transfer system such as dean room facilities of semiconductor and Flat Panel Display.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1913-1918
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• 2016

In order to analyze the power consumption pattern of the DC urban rail system, the method to obtain a solution establishing the current equation according to fixed position of the substation and varying position of the train is used. The proposed analysis method using the network analysis is to model the transfer function of the component constituting a direct current power supply system (dc substation, train, catenary) to the voltage and current. By multiplying the model formula consecutive, it can calculate the voltage and current of each element of power supply circuit and shows a simple case analysis.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.30-41
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• 1996

Current Source(CS) PWM converter is appropriate for the magnet power supply system which requests high power and high precision current control. Input and output filters should be installed to eliminate the current or voltage harmonics caused by the PWM switching for the CS PWM converter. But the input/output filters limit the output DC current range and may destroy the system with filter resonance, and make the system equation more complicated. In this paper, systematic and simple filter design method which considers not only the harmonic attenuation but also the total system good transfer function characteristics in the dc filter. The simulated and experimental results verify the proposed theory. (author). refs., figs., tabs.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1132-1136
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• 2014

In the context of increasing electric energy consumption in a data center, energy efficiency improvement is strongly emphasized. In a data center, electric energy is largely consumed by DC power supply system, which is based on a rectifier composed by multiple parallel converters. Therefore, rectifier efficiency must be improved for minimizing loss of DC power supply system. Rectifier efficiency can be modulated by load allocation to converters because converter efficiency depends on input AC power. In this paper, we propose a new control method to maximize rectifier efficiency. The method can control load allocation to converters by introducing active power converter control scheme and start-and-stop of converters. In order to illustrate optimal load allocations in a rectifier, a maximization problem of rectifier efficiency is formulated as a nonlinear optimization one. The problem is solved by Lagrangian relaxation method and the computation results provide the validity of proposed method.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.902-904
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• 1993

This paper contains the terminal developement for the feeder remote unit in Korea Distribution Automation System. This terminal unit has serval functions in order to do feeder auotmation as following, the open/close controls and gathering status informations of switchgears, getting line currents and voltages, distribution fault. So FRU has four modules to do those functions-Logic Controller, Relay Controller, Data Acquisition, Display, Power Supply etc. The FRU should be on allays, so AC power is supplied before & behind the switchgear. Power Supply is made up with AC/DC, DC/DC, Battery and/or SOLAR CELLS & CONTROLLER. It is important for the supply to protect against some Surges, because surges are happened so many times. Surge test is fellowing the standard IEC 801-5 or IEEE 587.

• KIPE Magazine
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• v.5 no.5
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• pp.45-46
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• 2000

-방사능 유출우려가 있는 지역에서의 제어목적 -초정밀도의 Magnet 등의 부하목적 -고신뢰성의 Power Supply

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.619-625
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• 2008

Electrical Power supply System conditions of korea high speed train consists of main transformer, four AC-DC PWM converter of Auxiliary Block, Battery Charger in Power Car and Trailer Car, Trailer Inverter, Auxiliary inverter. Main transformer, at nominal voltage of 25kv supplied to secondary winding nominal output Voltage 383Vac, The Auxiliary block consists of AC-DC converters for generating 670VDC power, Auxiliary inverters for ventilation and air compressor, Trailer car inverter provide three phase power supplies at 440Vac for air conditioning and heating. The Battery charger Trailer and Power car supplies 72VDC all necessary equipment to energize the trainset equipment and suppy essential control. This Paper introduces the combined test results of the power supply system for korea high speed train. The main purpose of this combined test is to verify the performance of the power supply system that is designed to operate up to full load test.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.85-86
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• 2017

본 논문에서는 DC 48V 전원 공급이 가능한 600W급 PV ESS( Energy Storage system)시스템에 대하여 제안한다. PV 입력부는 100V이하의 전압 입력에서 사용할 수 있도록 3레벨 부스트(Three level boost)컨버터로 구성하였다. 배터리는 양방향 DC/DC 컨버터를 사용하였고 DC48V부는 벅 컨버터로 구성하였다. 제안한 시스템의 검증하기 위하여 시뮬레이션과 600W PV ESS 시스템을 구성 실험을 진행하였다.