• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2003년도 추계학술발표대회 개요집
• /
• pp.147-149
• /
• 2003

Many factors, such as welding current, welding time, force, electrode shape, the output stability of a welding machine, are closely related with micro spot series welding. Of those factors, the output stability evaluation of the welding machine would be checked first. in this study, we applied 6$\sigma$ to evaluation for the output stability of the welding machine. We estimated output stability and control stability of the welding machine by using Cp(process capability), Ppk and 4-block diagram. Therefore the problem as solved in micro spot series welding process and the problem of output control in welding machine by 6$\sigma$ tool.

• 대한전기학회논문지
• /
• 제39권3호
• /
• pp.263-272
• /
• 1990

In the variable speed driving system of a three phase induction motor controlled by a PWM inverter, the output terminal contains considerable amount of harmonic components of the voltage waveform due to the switching action of semiconductor devices, causing torque ripples, acoustic noise and oscillation of the motor. This paper describes a new algorithm which eliminates the harmonics and controls the fundamental voltage in three phase PWM inverter output waveform. The new algorithm utilizes the technique of particular harmonics elimination (PHE) by walsh series in three phase PWM inverter output waveform. A microprocessor (8086 CPU)-controlled three phase induction motor system is described to realize this algorithm. The system is designed for 3 phase output voltage in the 1-60Hz interval where 5th and 7th harmonics, and 5th, 7th, 11th, and 13th harmonics are eliminated. Also, the fundamental wave amplitude is designed to be proportional to the output frequency. The performance of the proposed method shows sufficient elimination of the harmonics and also reduction of computation time which determines switching pattern. The proposed PWM pattern by Walsh series, is effective not only to induction motors but also to other electromagetic equipments such as voltage regulators and UPS.

• Journal of Power Electronics
• /
• 제10권6호
• /
• pp.673-679
• /
• 2010

Input-series-output-parallel (ISOP) connected DC-DC converters enable low voltage rating switches to be used in high voltage input applications. In this paper, a DSP is adopted to generate digital phase-shifted PWM signals and to fulfill the closed-loop control function for ISOP connected two full-bridge DC-DC converters. Moreover, a stable output current sharing control strategy is proposed for the system, with which equal sharing of the input voltage and the load current can be achieved without any input voltage control loops. Based on small signal analysis with the state space average method, a loop gain design with the proposed scheme is made. Compared with the conventional IVS scheme, the proposed strategy leads to simplification of the output voltage regulator design and better static and dynamic responses. The effectiveness of the proposed control strategy is verified by the simulation and experimental results of an ISOP system made up of two full-bridge DC-DC converters.

• Journal of Power Electronics
• /
• 제9권2호
• /
• pp.300-307
• /
• 2009

In this paper, design and control is proposed for a four input-series-output-series-connected ZVS full bridge converter for the photovoltaic power conditioning system (PCS). The novel topology for a photovoltaic (PV) DC/DC converter that can dramatically reduce the power rating and increase the efficiency of a PV system by analyzing PV module characteristics is proposed. The control scheme, including an input voltage controller is proposed to achieve equal sharing of the input voltage as well output voltages by a four series connected module. Design methods for ZVS power stage are also introduced. The total PV system is implemented for a 250-kW PV power conditioning system (PCS). This system has only three DC/DC converters with a 25-kW power rating and uses only one-third of the total PV PCS power. The 25-kW prototype PV DC/DC converter is introduced to verify experimentally the proposed topology. In addition, an experimental result shows that the proposed topology exhibits good performance.

• Journal of Power Electronics
• /
• 제15권4호
• /
• pp.886-898
• /
• 2015

The design feasibility of a micro unidirectional DC transmission system based on an input-parallel output-parallel (IPOP) converter is analyzed in this paper. The system consists of two subsystems: an input-parallel output-series (IPOS) subsystem to step up the DC link voltage, and an input-series output-parallel (ISOP) subsystem to step down the output voltage. The two systems are connected through a transmission line. The challenge of the delay caused by the communication in the control system is addressed by introducing a ring communication structure, and its influence on the control system is analyzed to ensure the feasibility and required performance of the converter system under practical circumstances. Simulation and experiment results are presented to verify the effectiveness of the proposed design.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2015년도 전력전자학술대회 논문집
• /
• pp.265-266
• /
• 2015

A multiple output dc-dc resonant converter topology for an independent voltage control technique is proposed, using a narrow frequency selection band-pass filters. The multi-output converter is supplied by a single source inverter with the superposed sinusoidal signals reserved for each output. A series-series parallel resonant topology is utilized to implement the narrow frequency selection channels for minimum interference. Finally the experimental setup for four output dc-dc converter is verified with the narrow channel frequencies of 26 kHz, 32 kHz, 38 kHz and 46 kHz.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.904-905
• /
• 2008

In this paper, a novel 60kV, 300A, 3kHz pulsed power supply based on IGBT stacks is proposed. Proposed scheme consists of series connected 9 power stages to generate maximum 60kV output pulse and 15kW series resonant power inverter to charge DC capacitor voltage. Each power stages are configured as 8 series connected power cells and each power cell generates up to 830VDC, 300A pulses. Finally pulse output voltage is applied using total 72 series connected IGBTs. The synchronization of gating signal is important of series operation of IGBTs. For gating signal synchronization, full bridge inverter and pulse transformer generates on-off signals of IGBT gating and specially designed gate power circuit was used.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
• /
• pp.917-918
• /
• 2006

In this paper, a novel new pulse power generatorbased on IGBT stacks is proposed for pulse power application. Proposed scheme consists of series connected 9power stages to generate maximum 60kV output pulse and one series resonant power inverter to charge DC capacitor voltage. Each power stages are configured as 8 series connected power cells and each power cell generates up to 850VDC pulse. Finally pulse output voltage is applied using total 72 series connected IGBTs. The synchronization of gating signal is importantfor series operation of IGBTs. For gating signal synchronization, full bridge inverter and pulse transformer generates on-off signals of IGBT gating and specially designed gate power circuit was used.

• Journal of Power Electronics
• /
• 제10권3호
• /
• pp.245-250
• /
• 2010

Input-series-output-parallel (ISOP) converters consisting of multiple modular DC/DC converters can enable low voltage rating switches to be used under high voltage input applications. This paper presents a digital control strategy, which can achieve equal sharing of input voltage for a modular ISOP system consisting of two-transistor forward DC/DC converters by forcing the input voltages of neighboring modules to be equal. The proposed scheme is analyzed using small signals analysis based on the state space average method. The performance of the proposed control strategy is verified with an experimental prototype of an ISOP converter made up of three two-switch forward converters.

• 전력전자학회논문지
• /
• 제14권3호
• /
• pp.177-187
• /
• 2009

본 논문에서는 다중 출력을 갖는 LLC 직렬 공진 컨버터의 입출력 이득에 대한 새로운 해석법을 제시한다. 특히 Math-CAD 시뮬레이션을 통해 변압기 2차 측 누설인덕턴스 성분에 의한 주파수 이득특성 변화를 분석한다. 유도된 수식 이론을 근거로, 3개의 출력을 갖는 430W급 공진 컨버터를 제작하여 46인치용 PDP 파워모듈의 Sustain 블록에 적용함으로서, 제안된 해석법의 정확성을 검증한다.