• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.43-51
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• 2010

Conventional UPS(Uninterruptible Power Supply) using batteries for assisting the source is limited by the large volume and the life-time of battery. Moreover, voltage variation caused by the sudden load variation brings the problems on UPS system output. In this paper, the battery using fuel cell which is environment-friendly alternative energy is connected on AC/DC converter for UPS to compensate the sudden load variation energy and make the stable power.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.74-76
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• 2007

In this paper a maximum power point tracking(MPPT) techniques for power of PV(photovoltaic) systems are presented using boost converter for a connected single phase inverter. On the basic principle of power generation for the PV module, algorithms for maximum power point tracking are described by utilizing a boost converter to adjust the output voltage of the PV module. Based on output power of a boost converter, single phase inverter uses predicted current control to control four IGBT's switch in full bridge. Furthermore a low cost control system for solar energy conversion using the DSP is developed, based on boost converter to adjust the output voltage of the PV module. The effectiveness of the proposed inverter system is confirmed experimentally and by means of simulation. Finally, experimental results confirm the superior performance of the proposed method.

• Journal of Power Electronics
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• v.13 no.3
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• pp.419-428
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• 2013

The modular multilevel cascade converter (MMCC) is a new family of multilevel power converters with modular realization and a cascaded pattern for submodules. The MMCC family can be classified by basic configurations and submodule types. One member of this family, the Hexverter, is configured as Double-Delta Full-Bridge (DDFB). It is a novel multilevel AC/AC converter with direct power conversion and comparatively fewer required components. It is appropriate for connecting two three-phase systems with different frequencies and driving an AC motor directly from a utility grid. This paper presents the dq model of a Hexverter with both of its AC systems by state-space representation, which then simplifies the continuous time-varying model into a periodic discrete time-invariant one. Then a generalized multivariable optimal control strategy for regulating the Hexverter's independent currents is developed. The resulting control structure can be adapted to other MMCCs and is flexible enough to include other control criterion while guaranteeing the original controller performance. The modeling method and control design are verified by simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.1
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• pp.37-43
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• 2020

This study proposes a 7kW low-voltage DC-DC converter (LDC) using a coupled inductor (CI) for heavy hydrogen electric transport vehicles. The LDC uses a phase-shift manner for soft switching. SiC-MOSFET is used to reduce the loss of reverse recovery current through the use of a high switching frequency. LDC is require large transformer and inductor because of large output current. The size of transformer and inductor can be reduced by deviding the transformer and inductor into two pieces each. This work presents the experimental results of the proposed circuit.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.753-755
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• 1993

Full Bridge Diode Rectification and Phase Controlled SCR Rectification are the most widely used methods of power conversion($AC{\rightarrow}DC$) in Power Electronic products such as UPS systems. But using these types of converters can lead to the following problems. First, they generate harmonics on the AC input side, which can cause interference in other equipment connected to the same commercial power line. Second, they deteriorate the power factor so that the input power capacity or the equipment becomes larger than the actual rated output capacity. As a means to overcome these problems an IGBT type PWM Converter, which applies a current control algorithm, is proposed. In this paper the enhancement of the converter performance is shown through simulation.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.519-528
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• 2019

Current brake system changes the kinetic energy into heat energy by friction-type of brake that the braking action is diverging into the air. The system has a device called a retarder that generates braking force. High-tech research on the high-speed response characteristics of retarders utilizing part of the braking energy of the retarder to save electrical energy consumption is already underway in advanced countries. In this paper, we propose DC-DC converter which converts 3-phase voltage generated from retarder to 24V DC voltage for battery charging and verify its validity through experiments.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.351-355
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• 2016

Welding machines are high-capacity systems used in a low-frequency range using IGBT. As their system is similar to a large transformer, most welding machines suffer a great loss because of hard switching and vast leakage inductance. A voltage-balancing circuit is designed to overcome these shortcomings. This circuit can reduce the transformer size by making it into a high frequency and reducing the input voltage by half and by adopting a serial structure that connects two full-bridges in a series to use a MOSFET with a good property at high frequency. In addition, a Schottky diode is used in the primary rectifier to overcome the low efficiency of most welding machines. To use the Schottky diode with a reliably relatively low withstanding voltage, an active snubber is adopted to effectively limit the ringing voltage of the diode cut-off voltage.

• Journal of Power Electronics
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• v.5 no.1
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• pp.55-61
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• 2005

A fuel cell (FC) system includes a fuel processor plus subsystems to manage air, water, and thermal energy, and electric power. The overall system is high-priced and needs peripheral devices. In this paper, a FC simulator is designed and constructed with the electrical characteristics of a fuel cell generation (FCG) system, using uses a simple buck converter to overcome these disadvantages. The characteristic voltage and current (V-I) curve for the FC simulator is controlled by a simplified linear function. In addition, to verify FCG system performance and operation, a full-bridge DC/DC converter and a single-phase DC/AC inverter were designed and constructed for FC applications. Close agreement between the simulation and experimental results confirms the validity and usefulness of the proposed FC simulator.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.484-486
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• 2004

In this paper, the power electronics requirement and the controls of an induction motor for fuel cell electric vehicle system are presented. The power topology is selected based on performance, cost, size, volume, manufacturability, component count and simplicity. Another highlight of the topology is the reduction of battery bank and its control strategy. The proposed approach consists a full-bridge DC/DC converter to boost the fuel cell voltage. The induction motor operated with vector control is driven by a three-phase PWM inverter supplied by the DC-link voltage. The investigation of the electric vehicle performed due to parameter variation of the induction motor has been presented.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.345-347
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• 1994

It is importent to have the switching frequency of power supplies increase in order to reduce their size and weight. But according to increasing the switching frequency, there are several defacts - that is switching losses, high voltage/current stresses and conduction losses and so on. That's why soft switching method was proposed. This paper presents the simulation and analysis of the new proposed Full bridge Zero-Voltage-Transition PWM DC-DC converter for developing that unit. This circuit doesen't increase the voltage and current stresses of main MOSFET switches. Voltage type quasi-resorent method is applied and expected high effenciency. Switching frequency is 100KHz and main switches are MOSFET.