• Journal of Power Electronics
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• 제15권5호
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• pp.1168-1177
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• 2015

This paper presents a scheme to improve the line current distortion of power factor corrector (PFC) topology at the zero crossing point using a predictive control algorithm in both the continuous conduction mode (CCM) and discontinuous conduction mode (DCM). The line current in single-phase PFC topology is distorted at the zero crossing point of the input AC voltage because of the characteristic of the general proportional integral (PI) current controller. This distortion degrades the line current quality, such as the total harmonic distortion (THD) and the power factor (PF). Given the optimal duty cycle calculated by estimating the next state current in both the CCM and DCM, the proposed predictive control algorithm has a fast dynamic response and accuracy unlike the conventional PI current control method. These advantages of the proposed algorithm lower the line current distortion of PFC topology. The proposed method is verified through PSIM simulations and experimental results with 1.5 kW bridgeless PFC (BLPFC) topology.

• 조명전기설비학회논문지
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• 제12권3호
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• pp.67-73
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• 1998

본 연구에서는 기존의 정류회로가 포함하고 있는 고조파 발생과 역률저하문제를 개선하기 위한 방안으로 BPFC(Boost Power Factor Collection)방식을 사용하였다. 이 BPFC는 고역률올 구현하기 위해 가장 널리 쓰이는 방식중의 하나로서 입력전압과 거의 동둥한 지속적인 인덕터 전류를 정현파에 가까운 형태로 제어할 수 있다는 장점을 가지고 있다. 또한 BPFC는 제어방식에 의해 크게 달라질 수 었다. 본 논문에서는 순간모드선택 피크 전류제어방식과 PWM 평균전류 재어방식을 이용한 고역률 저고조파를 갖는 정류회로를 구성하여 각각에 대하여 비교분석하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.96-96
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• 2009

The purpose of this study is to clarify the transitional behavior and main factor of excessive welding distortion caused by fabrication process of STS 304 vacuum vessel having double curvature for the efficient quality control of vacuum vessel. In order to do it, the predictive equations of the welding distortion in simple weldment of vacuum vessel were established by conventional finite element analysis. And the principal factor controlling the welding distortion was identified by evaluating the welding distortion of vacuum vessel in each fabrication process with FEA and simplified thermo elastic method. Based on the results, the principal factors of distortion of vacuum vessel were clarified as angular distortion and transverse shrinkage which are a source of excessive out-of plane distortion in the double curved vacuum vessel. It was expected that the FE analysis results of this study could contribute to establish the proper control method of welding distortion for double curved vacuum vessel.

• Journal of Welding and Joining
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• 제28권5호
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• pp.64-68
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• 2010

The purpose of this study is to develop the control technology of global distortion in the deck of superstructures during manufacturing processes. The behavior of global distortion in the deck was evaluated by FEA and verified through comparing with the measured results by 3D measuring instrument. It was seen from the results that the principal factor inducing the global distortion is to be the bending moment associated with the longitudinal shrinkage force and transverse shrinkage caused by welding of stiffeners and flame heating to correct the excessive local out-of-plane distortion. Based on the results, the amount of reverse distortion in the thin deck plate was determined to control the global distortion in the deck plate. The proposed distortion control technology was verified by applying it to the actual structure.

• 한국컴퓨터정보학회논문지
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• 제29권6호
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• pp.143-151
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• 2024

본 논문은 부스트 PFC (Power Factor Correction) 컨버터의 경부하시, 컨버터의 인덕터 전류 왜곡을 수학적으로 분석하고 원인을 정의한다. 경부하시 평균 전류 모드제어에서 인덕터 전류가 불연속적으로 도통하게 되어 부정확한 인덕터 전류 평균값이 전류 제어에 반영된다. 예측 전류 모드제어에서는 인덕터 전류에 비해 전류 리플이 상대적으로 커져 전류 왜곡이 심해진다. 또한 모델 예측 전류제어의 경우 인덕터 전류의 첨두치 부근에서 스위치가 OFF된다. 인덕터 전류 왜곡은 total harmonic distortion 증가와 역률 감소를 유발하기 때문에 반드시 해결되어야 한다. 본 논문은 수학적 분석을 기반으로 부스트 PFC 컨버터의 경부하시 전류 왜곡을 완화할 수 있는 설계 절차를 선정한다. 마지막으로 hardware-in-the-loop simulation을 사용하여 경부하시 제어 방법들을 비교분석했다.

• Journal of Power Electronics
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• 제14권5호
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• pp.890-898
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• 2014

Critical conduction mode boost power factor correction converters operating at the boundary of continuous conduction mode and discontinuous conduction mode have been widely used for power applications lower than 300W. This paper proposes an enhanced variable on-time control method for the critical conduction mode boost PFC converter to improve the total harmonic distortion characteristic. The inductor current, which varies according to the input voltage, is analyzed in detail and the optimal on-time is obtained to minimize the total harmonic distortion with a digital controller using a TMS320F28335. The switch on-time varies according to the input voltage based on the computed optimal on-time. The performance of the proposed control method is verified by a 100W PFC converter. It is shown that the optimized on-time reduces the total harmonic distortion about 52% (from 10.48% to 5.5%) at 220V when compared to the variable on-time control method.

• Journal of Power Electronics
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• 제16권1호
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• pp.66-73
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• 2016

The quantity of alternating current (AC) leakage and the value of distortion factor in capacitor currents are discussed with regard to a new power component called variable capacitance device (VCD). This component has terminals for controlling its capacitance. Nonlinear dielectric characteristics are utilized in this device to vary the capacitance. When VCD operates in an AC circuit, the AC leakage from this device through direct current (DC) control voltage source increases according to the conditions of DC control voltage and so on. To solve this problem, we propose techniques for suppressing AC leakage. Although VCD has strong nonlinear characteristics, the current through the capacitor is not distorted significantly. The relations between AC leakage and the distortion in current waveforms are investigated. An application example for an AC power regulator is also introduced to evaluate the distortion in waveforms.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.362-365
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• 1999

In this paper, the method of reducing harmonics and correcting of power factor in single PWM converter associated with diode rectifier and boos converter is studied. The ac-dc converter in which the harmonic distortion in the input current is reduced using a third harmonic injected PWM is proposed. A lower switching power loss and easy configuration o control circuit are obtained by adopting discontinuous current mode. Simulation and experimental results of ac-dc converter with 5[KHz] switching frequency are presented and correction of power factor and reduction of total harmonic distortion was established.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.1999-2001
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• 1997

The main two drawbacks of the Sin91e Stage PFC (SS-PFC) converters employing a DCM Boost PFC cell are relatively high voltage stress on the bulk capacitor and the input current harmonic distortion. The high voltage stress on bulk capacitor makes the SS-PFC converter impractical in a universal input application and the input current harmonic distortion lowers power factor. In this paper a selective variable frequency control that reduces the voltage stress on the bulk capacitor and the input current harmonic distortion is proposed. Computer simulation results of the proposed control method are presented.

• 전력전자학회논문지
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• 제4권1호
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• pp.82-90
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• 1999

본 논문은 단일 스위치 3상 ZCS 강압형 정류기의 펄스주파수 제어기법을 다루고 있다. 제안하는 펄스주파수 제어방법은 거의 정현적인 입력전류를 흐르게 하여 3상 강압형 정류기의 성능을 보여준다. 제안하는 제어구조의 유용성을 검증해 주는 시뮬레이션과 실험 결과는 단일 스위치 3상 ZCS 강압형 정류기의 고역율, 입력전류의 낮은 THD, 부하 변동에 대한 전압의 응답특성들이 뛰어남을 보여준다.