• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.495-497
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• 1994

Given the constraint of the AC input power factor and the DC-link voltage and current ripple in voltage source inverter, minimizing the size and cost of the DC-link fitter components is very important. This paper presents a procedure for the selection of DC-link filler element values in a three-phase PWM voltage source inverter-fed induction motor drive system, which can not only satisfy the requirements for the system performance but also minimize the filter size.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.711-716
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• 2003

본 논문은 5KW급의 SOFC와 저전압 배터리를 복합전원으로하는 10kw급 독립형 연료전지발전시스템의 전력 변환장치의 개발에 관한 것이다. 이를 위한 전력변환장치는 연료전지로부터의 저전압을 상승시키기 위한 고주파 DC-DC 컨버터 및 이를 안정된 교류전원으로 변환하기 위한 DC-AC 인버터 그리고 저전압 배터리를 충$\cdot$방전하기 위한 양방향 DC-DC 컨버터로 구성된다. 미국 에너지부 및 IEEE가 주최한 "2003 International Future Energy Challenge Competition"에서 제시한 90$\%$이상의 효율과 $\$40/KW$ 이하의 양산가등의 사양을 목표로 개발된 본 전력변환장치에 대한 토폴로지, 주요 부품의 설계 및 제어방식에 관하여 기술하고 실험결과를 제시한다.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.103-105
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• 2008

DC-DC 컨버터, DC-AC (계통연계형)인버터, 입 출력 필터 등으로 구성된 연료전지용 PCS에서 DC-DC 컨버터가 전체 효율에 가장 많은 영향을 미친다고 할 수 있는데 본 논문에서는 Push-Pull 컨버터를 선정하여 손실에 관하여 해석하였다.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.171-172
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• 2015

용접기는 3상 교류 입력을 받아 정류기를 거쳐 DC/DC 컨버터를 통하여 저전압, 대전류의 출력을 이용하여 금속 재료를 용접한다. 기존의 용접기는 대용량 시스템으로 IGBT를 이용하여 주파수가 낮은 범위에서 사용되므로 변압기 등 시스템 크기가 매우 크다. 본 논문에서는 고주파화를 통하여 용접기의 크기를 줄이는 것이 목적으로 용접기의 구성 중 브리지 다이오드로 구성된 간단한 구조인 입력 AC/DC부를 제외한 인버터, 변압기, 정류기, 출력 인덕터를 포함하는 DC/DC 컨버터를 설계하고 실험 검증하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.117-122
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• 2018

A large-capacity three-phase system air conditioner recently includes an inverter circuit to reduce power consumption. The inverter circuit uses a DC voltage that comes from DC-link power capacitor with the function of rectifying, which means AC voltage to DC voltage using a diode. An electrolytic capacitor is generally used to satisfy the voltage ripple and current ripple conditions of a DC-link power capacitor used for rectifying. Reducing the capacitance of the capacitor decreases the size, weight, and cost of the circuit. This paper proposes an algorithm to reduce the input ripple current by combining the minimum point estimation phase locked loop (PLL) phase control and the average voltage d axis current control technique. When this algorithm was used, the input ripple current decreased by almost 90%. The current ripple of the DC-link capacitor decreased due to the decrease in input ripple current. The capacitor capacity can be reduced but the electrolytic capacitor has a heat generation problem and life-time limitations because of its large equivalent series resistance (ESR). This paper proposes a method to select a film capacitor considering the current ripple at DC-link stage instead of an electrolytic capacitor. The capacitance was selected considering the voltage limitation, RMS (Root Mean Square) current capacity, and RMS current frequency analysis. A $1680{\mu}F$ electrolytic capacitor can be reduced to a $20{\mu}F$ film capacitor, which has the benefit of size, weight and cost. These results were verified by motor operation.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.399-402
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• 1999

The single sensor technique reconstructing phase currents from the dc-link current without phase current sensors in proposed. When the duration of active vector is too short for the snubber current to reduce, the dc-link current including the snubber current gives large detection error. The solution is presented by analyzing the snubber current and modifying the switching sequences. This scheme is simple, requires only one sampling a period and has good results for detecting the phase currents.

• Journal of Industrial Technology
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• v.18
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• pp.323-328
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• 1998

A current controlled VSI-PWM rectifier and inverter with capacitor dc link is regarded as one of the most promising structures for three-phase to three-phase to three-phase power conversion. This type of converter normally requires twelve switches for a rectifier and inverter composed of self turn-off switch such as a bi-polar transistor or IGBT with an anti-parallel diode. In this paper, a new three-phase to three-phase converter for ac motor drives is proposed. The proposed converter employs only eight switches and has the capability of delivering sinusoidal input currents with unity power factor and bidirectional power flow. This paper describes the feasibility and the operational limitations of the proposed structure. A mathematical model of the system is derived using generalized modulation theory and experimental results for steady state and dynamic behavior are presented to verify the developed model.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.115-116
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• 2015

Grid voltage variation is usually happened but existing PV inverter dose not consider this variation before inverting into AC power. This inverting is a cause of unnecessary losses. This paper proposes that DC-link should be changed for removing those losses. Furthermore, maximum efficiency tracking control algorithm with variable DC-link voltage is proposed and verified by simulation and experiment.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.464-468
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• 1999

This paper deals with the harmonic reduction technique in square-wave inverters which can regenerate the dc power from dc bus line to ac bus line in substations for traction systems. To reduce the harmonics, two 6-pulse inverters are used for 12-pulse operation and zigzag-connected output transformers for eliminating the harmonics of 6(2m-1)$\pm$1 orders. And an ac filter is furnished at output side. In spite of the square-wave three-phase inverters, computer simulations show that the THDs of the output voltage and current are 2.55% and 0.554%, respectively.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.463-465
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• 2005

This paper proposes a regeneration inverter system, which can regenerate the excessive power form the DC bus line to the AC source for traction systems. The proposed regeneration inverter system for DC traction can reduce harmonics which is a characteristic of the AC current source. The simulation was composed as a prototype model[3.7kW]. Finally, it is shown that the inverter can successfully operate in regeneration mode.