• Journal of Power Electronics
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• 제18권3호
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• pp.879-891
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• 2018

A bidirectional dc-dc converter is used in battery energy storage systems owing to the growing requirements of a charging and discharging mode of battery. The magnetic coupling of output or input inductors in parallel-connected multi modules of a bidirectional dc-dc converter is often utilized to reduce the peak-to-peak ripple size of the inductor current. This study proposes a novel design guideline to achieve minimal ripple size of the inductor current under bidirectional power flow. The newly proposed design guideline of optimized coupling factor is applicable to the buck and boost operation modes of a bidirectional dc-dc converter. Therefore, the coupling factor value of the coupled inductor does not have to be optimized separately for buck and boost operation modes. This new observation is explained using the theoretical model of coupled inductor and confirmed through simulation and experimental test.

• 전력전자학회논문지
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• 제3권4호
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• pp.280-286
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• 1998

본 논문에서는 벡터제어방식의 인버터에 의하여 구동되는 교류전동기 제어 시스템에서 전류특정회로에서의 측정오차에 기인하는 전동기의 토크리플을 저감하는 방법을 제안한다. 2상의 전류를 측정하는 회로에서의 오프셋 전압과 전압증폭률이 서로 다를 때 전동기 출력토크에 발생되는 리플을 각각 정량적으로 분석하고, 이로부터 온라인 상태에서 실시간으로 토크리플을 제거할 수 있는 알고리즘을 제시하였다. 제안된 방식의 유용성을 확인하기 위하여 이를 영구자석형 동기전동기에 적용하였을 경우에 대하여 출력토크의 리플을 계산하고 이를 제거하는 알고리즘을 컴퓨터로 시뮬레이션하였다.

• Journal of Power Electronics
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• 제17권3호
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• pp.590-600
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• 2017

This paper presents a ripple-free input current modified interleaved boost converter for high step-up applications. By integrating dual coupled inductors and voltage multiplier techniques, the proposed converter can reach a high step-up gain without an extremely high turn-ON period. In addition, a very small auxiliary inductor employed in series to the input dc source makes the input current ripple theoretically decreased to zero, which simplifies the design of the electromagnetic interference (EMI) filter. In addition, the voltage stresses on the semiconductor devices of the proposed converter are efficiently reduced, which makes high performance MOSFETs with low voltage rated and low resistance $r_{DS}$(ON) available to reduce the cost and conduction loss. The operating principles and steady-state analyses of the proposed converter are introduced in detail. Finally, a prototype circuit rated at 400W with a 42-50V input voltage and a 400V output voltage is built and tested to verify the effectiveness of theoretical analysis. Experimental results show that an efficiency of 95.3% can be achieved.

• 전력전자학회논문지
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• 제26권2호
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• pp.96-105
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• 2021

Large-scale power converters consist of series or parallel module combinations. In these modular converter systems, the interleaving technique can be applied to improve capacitor reliability by reducing the ripple of the I/O current in which each module operates as a phase difference. However, when applying the interleaving technique for conventional three-level boost converters, the short-circuit period of the converter can be an obstacle. Such problem is caused by the absence of a low-level inductor of the conventional three-level boost converter. To solve this problem, a three-level boost converter with a low-level inductor is proposed and analyzed to enable interleaved operation. In the proposed circuit, the current ripple of the output capacitor depends on the neutral point connections between the modules. In this study, the ripple current is analyzed by the neutral point connections of the three-level boost converter that has a low-level inductor, and the effectiveness of the proposed circuit is proven by simulation and experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.159-161
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• 2007

$CO_2$ laser sees that is most suitable to get this effect through minimum formation damage and advantage that is root enemy of effect that happen in minimum cellular tissue depth of 0.1mm is stable living body organization or internal organs institution. Formation damage by ten can be related in formation's kind or energy density, length of evaporation time. If shorten evaporation time, surroundings cellular thermal damage 200 - because happen within 400ums laser beam in rain focus sacred ground surroundings cellular tissue without vitiation me by evaporation Poe of very small floor as is clean steam can. Application is possible to vulva cuticle cousins by a paternal aunt quantity, uterine cancer, cuticle tumor by laser system that $CO_2$ laser gets into standard in obstetrics and gynecology application. Because effect that super pulse output is ten enemies of laser if uniformity one pulse durations are short almost is decreased, most of all pulse module special quality of pulse style $CO_2$ laser for obstetrics and gynecology mode stabilization by weight very, in this research to get into short pulse duration and higher frequency density, do switching by high frequency in DC-DC Converter output DC's ripple high frequency to be changed, high frequency done current ripple amount of condenser for output filter greatly reduce can. Ripple of output approximately to Zero realization applying possible inductor realization through a special quality experiment do.

• 전자공학회논문지
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• 제52권6호
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• pp.50-56
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• 2015

본 논문에서는 모바일 응용에 적합한 고효율의 빠른 응답 특성을 가지는 히스테리틱 벅 변환기를 제안한다. 기존 히스테리틱 변환기의 문제점인 큰 출력 전압 리플과 작은 용량의 전력 인덕터 사용의 어려움을 삼각파 신호 발생기를 통해 해결하였다. 그리고 부하 전류에 따라 가변하는 스위칭 주파수를 PLL(Phase Locked Loop)구조를 사용하여 일정하게 함으로써 주변 IC에 미치는 EMI(Electro Magnetic Interference)잡음을 최소화 하였다. 이 회로는 BCDMOS 0.35um 2-poly 4-metal 공정으로 제작되었으며, 측정 결과 입력전압 3.7V, 출력전압 1.2V 부하 전류 50~500mA 범위에서 20mV 이하의 출력 전압 리플을 나타내며 170mA 이상의 부하 전류를 구동하는 경우 2MHz의 고정된 스위칭 주파수에서 동작하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권12호
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• pp.701-708
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• 1999

The PWM rectifiers are capable of supplying sinusoidal current control and unity power factor control on the input side and dc output voltage control on the output side. By applying nonlinear control to the PWM rectifiers, the responses of input current and output voltage can be improved and due to fast voltage control the output electrolytic capacitor can be reduced remarkably. In addition, it is checked whether or not the current capacity of the reduced-size capacitor allows the ripple current of the rectifier. The nonlinear control technique gives a good performance for supply voltage disturbances. The validity of the proposed scheme has been verified by the experiment using DSP.

• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.640-646
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• 2011

The current study presents the design and performance of a novel 4/2 switched reluctance motor (SRM) for a high-speed air blower. With a comparative study of some rotor structures for a high-speed drive, a stepper-type rotor is optimized to produce a continuous torque and a low torque ripple. Rotor pole arc is modified to have a wide continuous output torque region, and air gap is determined to develop less torque ripple. The rotor radius is determined to reduce torque ripple with a reiterative FEM analysis. The designed rotor has three regions: short uniform, long uniform, and nonuniform air-gap region. The positive torque region is wider than a conventional 4/2 SRM without any torque dead zone. A prototype is tested and the efficiency is up to 72[%] at 30,000[rpm], 600[w] output.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.867-869
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• 1993

In generally Boost Converter is used for Fuel Cell System. Because the output voltage of fuel cell is too small and greatly depends on the load condition, Boost Converter are required to boost and regulate the Fuel Cell voltage for per conversion efficiency. In this Paper, 6-phase Boost Converter is used to boost the Fuel Cell Voltage and regulate the output voltage. Multi phase converter hag some advantages such as low ripple and filter sine. About the Peak Current Control and compare of the Ripple Current of Boost Converter, we have studied.

• 한국IT서비스학회지
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• 제17권1호
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• pp.47-58
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• 2018

In this study, we define Fintech services as review previous literatures and identify the traditional Fintech service market for analysing the economic effects of the Fintech Industry by using the 2014 Input-Output Table. We can identify the current market of Fintech industry which consists of VAN, PG, financial SW, mobile banking and Fintech R&D and we conduct Input-Output analysis by using non-competitive import model. The Input-Output analysis results show that production inducement effect and front/rear chain effect of the Fintech Industry are below average of other industries. This is because the Fintech technology and industry were emerging in Korea at that time (2014), and thus the ripple effects are not significant. Especially, due to the existing white risk financial regulation, new business opportunities have not been open to adapt new ICT-financial technologies. Therefore, when the business ecosystem is build through deregulation and platforms of the financial sector, it is expected that the Fintech Industry will have a high ripple effect. In this study, we identify the current market of Fintech industry from ICT indusries and conduct Input-Output analysis. The economic effects of the Fintech industry are not remarkable, but it is significant to identify the emerging market and present the basic analysis of issued research field.