• 한국전자통신학회논문지
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• 제18권4호
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• pp.617-624
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• 2023

최근, 전자 제품의 소형화와 저소비전력화 및 향상된 효율과 역률개선이 큰 관심 사항이 되고 있다. 본 논문에서는 PWM 제어기반의 AC-DC 컨버터를 설계, 제작하였다. AC-DC 컨버터는 하나의 정류회로와 하나의 출력전압 제어 회로가 직렬로 연결되는 구조로 설계하였으며, 정류회로는 다이오드 기반 단상 전파전류 회로, 출력전압 제어 회로는 PWM 제어기반의 DC-DC 변환 회로를 적용하였다. PWM 제어를 위한 주 제어장치로 아두이노를 이용하였으며, LCD를 출력 단에 구성하여 제어 결과를 확인할 수 있도록 하였다. 시험회로를 통한 반복 실험들을 통해서 오실로스코프와 LCD에 디스플레이 되는 출력전압과 목표 출력전압의 오차를 확인하였으며, 오실로스코프 측정값을 기준으로 약 5%의 오차율을 보임으로써 제안된 설계 방법론의 유효성을 확인할 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.767-775
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• 2003

This paper considers the method of elimination harmonics in AC/DC converters, There are few practical methods to reduce the harmonics in AC/DC converters, particularly in filter design and control strategy. In this paper, a harmonic elimination methods are proposed, which includes hybrid PWM control strategy. These methods achieve precise output control along with the optimum performance simultaneously. The control method in this paper is developed to eliminate a fixed number of harmonics in AC to DC converter. The higher order harmonics can be easily eliminated by using filter proposed in this paper. The validity of these methods is confirmed experimentally.

• 해양환경안전학회지
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• 제16권2호
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• pp.235-240
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• 2010

백열전구를 대체하기위한 친환경 에너지 절약형 7w급 LED 램프의 구동을 위한 전원장치를 설계하였다. LED 램프는 칩 LED를 여러개 직 병렬로 연결하여 사용하게 되므로 적합한 직류 전압과 전류를 공급하여야 한다. 그런데 LED 램프는 상용 AC 220V 전원에 직접 연결해 사용하게 되므로 드라이버에는 전압제어와 전류제어가 포함된 AC/DC, DC/DC 전력변환기가 반드시 필요하게 된다. 따라서 본 논문에서는 램프의 LED 열에 따라 출력전압과 전류제어가 가능하며 변압기가 없는 간단한 구조의 LED 램프 드라이버를 설계하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1552-1553
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• 2011

The HVDC transformer which is one of the main equipments for HVDC(High Voltage Direct Current) electric power transmission systems is exposed to not only AC voltage but also the inflowing DC voltage which comes from the DC-AC converter systems. Therefore, the HVDC transformer insulation system is required to withstand the electric field stress under AC, DC and DC polarity reversal conditions. However the electric field distributions under those conditions are different because the AC electric field and DC electric field are governed by permittivity and conductivity, respectively. In this study, the changes of electric potential and electric field of conventional AC transformer insulation system under DC polarity reversal test condition were analyzed by FEM(Finite Element Method). The DC electric field stress was concentrated in the solid insulators while the AC electric field stress was concentrated in the mineral oil. In addition, the electric stress under that condition which is affected by the surface charge accumulation at the interfaces between insulators was evaluated. The stress in some parts could be higher than that of AC and DC condition, during polarity reversal test. The result of this study would be helpful for the HVDC transformer insulation system design.

• Journal of Power Electronics
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• 제10권3호
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• pp.328-333
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• 2010

A photovoltaic power conditioning system (PV PCS) that contains single-phase dc/ac inverters tends to draw an ac ripple current at twice the output frequency. Such a ripple current perturbs the operating points of solar cells continuously and it may reduce the efficiency of the current based maximum power point tracking technique (CMPPT). In this paper, the ripple current generation in a dc link and boost inductor is analyzed using the ac equivalent circuit of a dc/dc boost converter. A new feed-forward ripple current compensation method to incorporate a current control loop into a dc/dc converter for ripple reduction is proposed. The proposed feed-forward compensation method is verified by simulation and experimental results. These results show a 41.8 % reduction in the peak-to peak ac ripple. In addition, the dc/ac inverter control system uses an automatic voltage regulation (AVR) function to mitigate the ac ripple voltage effect in the dc link. A 3kW PV PCS prototype has been built and its experimental results are given to verify the effectiveness of the proposed method.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1495-1502
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• 2017

The Theory of operation of switched reluctance motors (SRM) depends on the reluctance torque, where energy is transferred to stator winding only. Although its construction is simple, the electrical design is complex, due to the switching configuration needed to deliver power to stator coils. However, because of the nonlinearly of magnetic circuit, SRM has torque ripple. This paper proposes a new strategy to drive SRM from a single-phase AC supply. Each stator winding is connected to AC-DC or AC-AC converters, which is called branch. All branches are connected in parallel to a single-phase AC supply. A shaft encoder allows current production in stator winding during the positive torque production region and terminates it during the negative torque production region. A magnetic flux is produced between stator poles when current is supplied from AC supply to stator coil and repeats many cycles as long as the rate of change of stator inductance is positive. Different possibilities for the configurations of AC-AC or AC-DC converters are introduced to drive SRM from the single-phase AC supply. A case study is presented for a SRM fed from AC supply through semi-controlled AC-DC converter is presented. A simulation model is introduced and verified by experimental rig for two-phase SRM.

• 전력전자학회논문지
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• 제14권6호
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• pp.488-495
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• 2009

본 논문은 기계적 에너지를 전기에너지로 변환하는 압전소자를 이용한 에너지 수확 시스템 내에서 전력변환을 수행하는 새로운 AC/DC 공진형 자려(自勵) 부스트 컨버터를 제안한다. AC/DC 공진형 자려 부스트 컨버터의 자려 스위칭을 위한 게이트 회로는, MOSFET 특성을 이용하여 압전소자 출력전압의 최대값을 검출하고 LC 공진회로의 특성을 이용하여 영전압 스위칭을 하며, 승압형 전력변환을 수행하기 위해서 별도의 전원을 필요로 하지 않는다. 제안된 컨버터 회로의 동작원리를 설명하고, 기존 연구 개발된 토폴로지와 비교, PSPICE 시뮬레이션 및 실험을 통하여 유용성을 검증한다.

• 대한전기학회논문지
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• 제45권2호
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• pp.216-223
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• 1996

The active power factor control AC/DC converter needs a current loop compensator to obtain better dynamic characteristics and power factor performance, but the optimal design of a current loop compensator is difficult because the AC/DC converter is a nonlinear system having periodically varying poles and zeros. The predictive current control scheme generates a control input using the dynamic equations of the AC/DC converter so that the dynamic of the AC/DC converter is included in the controller and the necessary bandwidth and the gain characteristics of the current control loop are satisfied. And as a result, a compensator becomes unnecessary and the current loop shows the improved current loop characteristics. In this paper, a power factor controller without current loop compensator by adopting a predictive current control scheme is designed and the designed power factor controller is modelled by using a small signal perturbation modelling technique, and simulated to investigate its small signal characteristics. A 200 W power factor control AC/DC converter is built to verify the effectiveness of the proposed power factor controller.

• Journal of Power Electronics
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• 제6권3호
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• pp.214-225
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• 2006

The design and performance analysis of a reduced rating autotransformer based thirty-pulse AC-DC converter is carried out for feeding a vector controlled induction motor drive (VCIMD). The configuration of the proposed autotransformer consists of only two single phase transformers, with their windings connected in a T-shape, resulting in simplicity in design, manufacturing and in a reduction in magnetics rating. The design procedure of the autotransformer along with the newly designed interphase transformer is presented. The proposed configuration has flexibility in varying the transformer output voltage ratios as required. The design of the autotransformer can be modified for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The proposed thirty-pulse AC-DC converter is capable of suppressing less than $29^{th}$ harmonics in the supply current. The power factor is also improved to near unity in the wide operating range of the drive. A comparison of different power quality indices at AC mains and DC bus is demonstrated in a conventional 6-pulse AC-DC converter and the proposed AC-DC converter feeding a VCIMD. A laboratory prototype of the proposed autotransformer based 30-pulse AC-DC converter was developed with test results validating the proposed design and system.

• 한국컴퓨터정보학회논문지
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• 제9권1호
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• pp.9-15
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• 2004

본 논문에서는 드레인 부근의 채널 영역에서 접합 전계를 줄이는 WSW(Wrap Side Wall) 구조의 소자를 제안하였다. WSW구조의 소자 제작은 첫 번째 게이트를 식각한 후에 NM1(N-type Minor1) 이 온주입을 하고 다시 질화막을 덮어 식각함으로서 만들어진다. 새로운 WSW구조는 전계를 줄이기 위한 버퍼층으로 되어 있으며 WSW소자와 LDD구조의 소자 수명을 비교하였으며 핫-캐리어 열화 특성도 분석하였다. 또한 AC 핫-캐리어 열화를 칩 상에서 평가하기 위해 펄스 발생기, 레벨 시프터, 주파수 분배기를 포함한 테스트 패턴 회로를 설계하였다. 이러한 것은 AC와 DC 스트레스간의 핫-캐리어 열화 조건이 AC와 DC 스트레스 모두 동일한 물리적 메커니즘을 지닌다는 것을 알 수 있었다. 따라서 일반적으로 회로 동작 조건 하에서 DC 핫-캐리어 열화 특성을 토대로 AC 소자 수명도 예측할 수 있었다.