• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1324-1331
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• 2014

This paper proposes a compensation PWM technique for the extension of output voltage ranges in three-phase VSI applications using three shunt resistors. The proposed technique aims to solve the dead zone, which occurs in high modulation indexes. In the dead zone, two phase currents cannot be sampled correctly, so that the three-phase VSI cannot be operated up to the maximum output voltage. The dead zone is analyzed in detail, and the compensation PWM algorithm is developed. The proposed algorithm is verified by numerical analysis and experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1983년도 하계학술회의강연.논문초록집
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• pp.106-109
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• 1983

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1169-1171
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• 2004

Voltage source inverters are required dead time to prevent the short current in the dc link. In recent years, the dead time effect has been investigated in many literatures. This paper presents on the novel space vector PWM inverter without dead time. The proposed inverter don't need to sense load current and to calculate for dead time compensation. Transformers are inserted each leg in the proposed inverter. The proposed method is analyzed each mode and then the simulation results verify the proposed method.

• 전력전자학회논문지
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• 제11권6호
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• pp.551-557
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• 2006

교류 전동기는 전류의 측정오차와 데드타임(dead time) 등의 영향으로 전기각주파수에 동기된 주기적인 토크리플이 발생한다. 본 논문에서는 주기적인 토크리플 보상알고리즘을 제안한다. 보상기는 토크리플에 의해 생성된 속도리플의 크기을 관측하는 속도리플 관측기와 관측한 양으로 토크리플을 보상하는 토크리플 보상기로 나누어진다. 본 논문에서는 토크리플 보상기의 해석을 통해 정상상태에서 속도리플이 제거되고 새롭게 제안된 속도리플 관측기을 적용하여 성능이 향상됨을 보였다. 제안한 주기적인 토크리플 보상알고리즘에 의해 토크리플 성분이 보상됨을 모의 실험과 실험을 통해 검증하였다.

• Journal of Power Electronics
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• 제9권3호
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• pp.438-446
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• 2009

The performance of direct torque controlled (DTC) interior permanent magnet (IPM) machines is poor at low speeds due to a few reasons, namely limited accuracy of stator voltage acquisition and the presence of offset and drift components in the acquired signals. Due to factors such as forward voltage drop across switching devices in the three phase inverter and dead-time of the devices, the voltage across the machine terminals differ from the reference voltage vector used to estimate stator flux and electromagnetic torque. This can lead to instability of the IPM drive during low speed operation. Compensation schemes for forward voltage drops and dead-time are proposed and implemented in real-time control, resulting in improved performance of the space vector modulated DTC IPM drive, especially at low speeds. No additional hardware is required for these compensators.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.232-237
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• 1991

Digital Variable Structure Controller(DVSC) is proposed to control variable speed recirculating pump for hot-water heating control system. In this study, nonlinear sliding line is used beyond output error boundary layer and PID sliding line is used within the layer. For long dead time compensation, constraint is added to Smith predictor algorithm. Steady state error is eliminated by using the proposed sliding line in spite of heating load change. By decreasing sampling time, good sliding motion is yielded but system output noise bv flow dynamics is amplified.

• 융합신호처리학회논문지
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• 제8권4호
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• pp.237-243
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• 2007

본 논문은 모바일 카메라 화질 개선을 위한 실시간 불량 화소(Dead pixel) 검출 및 보정 시스템에 대해 제안하고 있다. 영상 입력장치인 CIS(CMOS Image Sensor)는 소형화, 저전력, 비용절감의 효과로 각광받고 있다. 하지만 이미지 센서와 결합된 불량 화소 보정 장치에 관한 기존 방법에 있어서, 연속된 불량 화소들을 검출하지 못 하거나, 정상화소임에도 불구하고 불량 화소로 분류하여 영상이 훼손되는 경우가 발생한다. 제안된 알고리즘은 불량 화소를 핫 픽셀(Hot pixel)과 콜드 픽셀(Cold pixel)로 분류하여, 라인 검출방법과 $5{\times}5$ 창 검출 방법을 순차적으로 처리하여, 불량화소의 특성에 따라 검출 및 보정하는 방법을 제안한다. 라인 검출 알고리즘은 수평 저주파 영역의 불량화소를 검출한다. 그리고 $5{\times}5$창 검출 알고리즘은 수직, 대각 저주파 영역과 고주파 영역에 대한 불량 화소를 검출한다. 제안된 알고리즘은 시뮬레이션 결과, 99%의 높은 검출율을 보여주고 있다. 그리고 Verilog-HDL를 사용하여 구현하였고 Synopsys의 Design Analyzer와 TSMC 0.25um ASIC library로 합성하였으며, 총 Gate counts는 23K로 낮은 하드웨어 복잡도를 가진다.

• Journal of Power Electronics
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• 제9권2호
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• pp.232-242
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• 2009

In this paper, a matrix converter with improved low frequency output performance is proposed by achieving a one-step commutation owing to a general commutation circuit applicable to n-phase to m-phase matrix converters. The commutation circuit consists of simple resister and capacitor components, leading to a very stable, reliable and robust operation. Also, it requires no extra sensing information to achieve commutation, allowing for a one-step commutation like a conventional dead time commutation. With the dead time commutation strategy applied, the distortion caused by commutation delay is analyzed and compensated, therefore leading to better output linear behavior. In this paper, detailed commutation procedures of the R-C commutation circuit are analyzed. A selection of specific semiconductor switches and commutation circuit components is also provided. Finally, the effectiveness of the proposed commutation method is verified through a two-phase to single-phase matrix converter and the feasibility of the compensation approach is shown by an open loop space vector modulated three-phase matrix converter with a passive load.

• 설비공학논문집
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• 제8권1호
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• pp.65-75
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• 1996

A pilot plant, which is simplified the hot water heating control system of a large scale residential building, is used to investigate the effects of control methods and operating conditions on the system performance and to compare control characteristics. Digital variable structure controller(DVSC) and digital PI controller are implemented to control the speed of the circulating pump for the pilot plant using PC. For the DVSC, a control algorithm is suggested, which using a nonlinear sliding surface and a PID sliding surface outside and inside of output error boundary layer, respectively. Smith predictor algorithm is used for the compensation of long dead time. The suggested DVSC yields improved control performance compared with existing DVSC using linear sliding surface only. the system responses with the suggested DVSC shows good responses without overshoot for various operating conditions and robust under external disturbances compared with digital PI controller.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 추계학술대회 논문집
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• pp.41-43
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• 2013

PMSM 구동을 하였을 때, 인버터의 지령전압과 출력전압 사이에 왜곡이 발생하며, 대부분 Dead Time에 의한 영향 이다. 전압왜곡을 보상하는 여러 가지 방법 들이 연구되어왔다. 하지만 전압 왜곡의 보상이 abc 축 또는 dq축에서 이루어지고 있으나 어느 방식이 더 좋은지에 대한 검토가 없었다. 본 논문에서는 d-q축 전압방정식과 abc축 전압방정식으로부터 왜곡된 전압을 보상하는 방법을 비교한다.