Soo-Seok Kim

The Active Clamp Sepic- Flyback Converter

A high efficiency active clamp sepic-flyback converter is presented. The proposed converter is superposition of sepic converter mode and flyback converter mode. Not only sepic mode output but also flyback mode output can be fully regulated by constant frequency PWM control. Merging sepic and flyback topology can share the transformer, power MOSFET, and active clamp circuit. It has outstanding advantages over the conventional dc-dc converters with respect to high efficiency, high power density, and component utilization. The operation principle of the proposed converter is described and verified by simulation and experimental result

An improved scheme for high-efficiency push-pull converter using single winding self-driven synchronous rectification

This paper presents a method of synchronous rectifier (SR) for improving the efficiency in DC/DC converter. The proposed method is used push-pull topology on each half primary as a single winding self-driven synchronous rectification (SWSDSK). Specially, this method can improve efficiency to let SR switch turn on during dead time. Based on the novel design scheme for auxiliary winding in the power transformer, The SRs MOSFET is turn on fully even when the voltage in the transformer is zero. For verification, there are analyzed and compared improved single winding self-driven synchronous rectification (ISDSR) with various conventional SR topology.

Harmonic reduction of CO/sub 2/ welding machine using single-switch, three phase boost converter with sixth order harmonic injected PWM

In this paper, sixth order harmonic injected PWM for improving input current distortion of single switch three phase boost converter is presented. A periodic sixth order harmonic voltage is injected in the control circuit to vary the duty ratio of the converter switch within one switching cycle. As a result, the input phase currents are forced to track the input voltage and almost unity power factor is obtained. Experimental results are verified by a converter operating at 400 V/6 KW with three phase 140 V-220 V input and by a CO/sub 2/ arc welding machine which was nonlinear load with 3/spl phi/ 220 V input.

A Design of Power Converter for Fuel Cell Controlled by Micro-Processor

Recently, a fuel cell is remarkable for new generation system. The fuel cell is characterized by low voltage and high current. Therefor, for connecting to general load, it needs both a step up converter and an inverter. The proposed system consists of an isolated DC-DC converter to boost the fuel cell voltage to 380[Vdc] and a PWM inverter with LC filter to convert the dc voltage to single phase 220[Vac]. Also, bi-directional DC-DC converter for fuel cell generation system is composed to improve load response characteristic. In this paper, full bridge converter and the single phase inverter are designed and installed for fuel cell. Simulation and experiment verify that fuel cell generation system could be applied for the distributed generation.

The Analysis of Parallel Operating Characteristics for DC-DC Converter Using the Parallel Operation Model

Consideration for parallel operation in a high power system has been increased due to the advantages of parallel operation like as high productivity, simplicity of design, and redundancy of power. Based on the small signal model of DC-DC Converter, the simple and exact power stage model of parallel operation system is derived and the parallel operation system using current balance method for the uniform current distribution among the parallel operation system is proposed. Using Simulation programs, which consists of nonidentical Converter modules and changes the position of master and slave automatically, the current distribution error is kept within the limit in the parallel operation system. To verify the high performance of the proposed Converter system for parallel operation, the parallel operation test, which has 2 Converter modules of 1 kW, is accomplished. Also, the simulation result is good agreement with the experiment result in the transient and starting characteristics.

A novel isolated buck-boost converter

This paper proposed a novel Isolated Buck-Boost PWM DC-DC converter circuit. The topology which merged buck-boost mode with flyback mode can share the transformer and switch. Not only isolated buck-boost mode current but also flyback mode current added on the one output current of the converter because the topology merged buck-boost mode with flyback mode. A new converter has outstanding advantages over the conventional dc-dc converters with respect to high efficiency, high power density, and component utilization. The operation principle of the proposed converter is described and verified by simulation and experiment results. Also this paper presents novel circuit and simulation result of new active isolated buck-boost converter.

Fuel cell generation system with SEPIC-flyback converter

In this paper, the fuel cell generation system is proposed. Proposed system consists of SEPIC-Flyback converter and the single phase full-bridge inverter. The SEPIC-Flyback converter is coupled up SEPIC converter, which is capacitor energy storage type converter with the Flyback converter which is inductor energy storage type converter. In the fuel cell generation system, the ripple current of fuel cell output and the boosting ratio of the output voltage are important factors. Proposed SEPIC-Flyback converter is suitable for fuel cell application. This paper verifies the suitability as using the Matlab and PSIM program.

RF Power Conversional System for Environment-friendly Ferrite Core Inductively Coupled Plasma Generator

This paper is a study about a proper method of plasma generation to cleaning method and a high frequency power equipment circuit to generation of plasma that used cleaning of chamber for TFT-LCD PECVD. The high density plasma required for cleaning causes a possibility of high density plasma more than . It apply a ferrite core of ferromagnetic body to a existing ICP form. In case of power transfer equipment on 400[kHz] high frequency to generation of plasma it makes certain a stable switching operation in condition of plasma through using a inverter form for general purpose HB. And it demonstrates the performance of power transfer equipment using methods of measurement which use a transformer of series combination the density of plasma and the rate of dissolution of in condition of .

The development of RF generator for remote plasma cleaning source

Summary form only given, as follows. One of the major emissions of PFCs in semiconductor manufacturing is the in situ plasma cleaning procedure performed after the chemical vapor deposition of dielectric thin films. We have developed a new plasma cleaning technology that uses a remote plasma source to completely break down NF/sub 3/ gas into an effective cleaning chemical. A fluorine containing gas (NF/sub 3/, C/sub 2/F/sub 6/) is introduced in a remote chamber, where the plasma is sustained by application of RF energy. In the plasma, the clean gas is dissociated into changed and neutral species. The method has clear benefits Due to the high efficiency of the RF excitation, the NF/sub 3/ gas utilization removal efficiency can be as high as 90% in standard operating conditions. This ensures an extremely efficient source of fluorine, while virtually eliminating global warming emissions. With this remote technique, no plasma is sustained in the main deposition-chamber and the cleaning is much softer on the chamber components, compared to an in situ plasma cleaning technology.

The development of low frequency RF generator for dry scrubber

Summary form only given, as follows. Chemical vapor deposition reactors are widely used in the semiconductor industry for making insulating, semiconductive and conducting films in wafer fabrication. Dry scrubber system is to treat exhaust gases in semiconductor processing. Plasma is generated inside the electrode where the surface area to the plasma volume ration is high and the flow path is long. When process exhaust gases enter the dry scrubber system, they are forced to pass through the plasma region where energized electrons and ions collide with gas molecules and particles, generating reactive species, which react on expanded electrode surfaces. Solid components and particles are deposited on the electrode surfaces as dense films without reaction on the flow path and neutralized gases are pumped downstream. In this paper, we have studied on the low frequency RF generator for dry scrubber system. The main power stage of low frequency RF generator is used for the FB PWM inverter with an LC filter in the secondary circuit of the transformer. The operation of the Low frequency RF generator is identified. For this, we divided a switching period into six topological modes. 1500kW, 100kHz Low Frequency RF generator is designed and tested. Also, manual matching transformer provides an impedance match for any given process related variation in impedance. The operation characteristics of low frequency RF generator are verified by simulation and experimental results.