• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.701-702
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• 2006

A novel control strategy for the induction motor drive, based on the field acceleration method, is presented. The torque is controlled through variations of the stator flux angular velocity. The stator flux is controlled by using a feed forward control scheme, with the stator flux reference vector adjusted so as to obtain the fixed rotor flux amplitude.

• Journal of Power Electronics
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• 제16권1호
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• pp.249-258
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• 2016

Given that elastic connection is often used between motor drives and load devices in industrial applications, vibration often occurs at the load side. Vibration suppression is a crucial problem that needs to be addressed to achieve a high-performance servo-control system. Scholars have presented many strategies to suppress vibration. In this study, we propose a method to diminish vibration by using a torque feed-forward and disturbance torque observer. We analyze the system performance and explain the principle of the proposed vibration suppression method based on the transfer functions of the system. The design of controller parameters is another important issue in practical applications. We accordingly provide a succinct outline of the design specifications based on the coefficient diagram method. Furthermore, we build a model under the Simulink environment and conduct experiments to validate the proposed method. Results show that speed and position vibrations are successfully suppressed by the proposed method.

• 전자공학회논문지SC
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• 제46권1호
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• pp.63-67
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• 2009

전하 펌프의 전류 부정합은 위상 고정 루프의 주파수 성분에 기준 스퍼를 발생시킴으로써 특성을 떨어뜨리게 한다. 전류 부정합은 캐스코드 출력단과 같이 전하 펌프의 출력 저항을 높여줌으로써 감소시킬 수 있다. 그러나 공급 전압이 낮아짐에 따라 트랜지스터를 쌓기 힘들어지게 된다. 본 논문에서는 전류 부정합을 줄이기 위한 새로운 방법을 제안하였다. 제안한 방법은 출력 단의 채널 길이 변조에 의한 전류 변화를 피드포워드 방식으로 보상해 주는 것이다. 새로운 방법에 대한 시뮬레이션은 CMOS $0.18{\mu}m$ 공정을 이용하였다.

• 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.

• 전력전자학회논문지
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• 제15권3호
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• pp.226-234
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• 2010

본 논문은 실제적인 변압기 운전환경에서 변화하는 승압형 인덕턴스를 실시간으로 추정하여 그 값을 통해 이득값을 계산하는 전향제어기를 제안하였다. 승압형 인덕턴스는 입력 전류의 변화분과 입력 교류 전압의 측정치만을 이용하여 추정되고, 그 값은 최소자승법을 적용하여 최적화 된다. 제안된 전향제어기는 변압기 운전 환경의 변화에도 강인한 제어가 가능하며, 입력 전류의 고조파 성분을 감소시켜 간섭현상에 따른 성능 저하를 최소화 할 수 있다. 제안된 기법의 타당성은 시뮬레이션과 실험 결과를 통해 검증하였다.

• 한국소음진동공학회논문집
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• 제19권5호
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• pp.516-522
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• 2009

This paper proposes a new haptic cue vehicle accelerator pedal device using magnetorheological(MR) brake. As a first step, an MR fluid-based haptic cue device is devised to be capable of rotary motion of accelerator pedal. Under consideration of spatial limitation, design parameters are optimally determined to maximize control torque using finite element method. The proposed haptic cue device is then manufactured and integrated with accelerator pedal. Its field-dependant torque is experimentally evaluated. Vehicle system emulating gear shifting and engine speed is constructed in virtual environment and communicated with the haptic cue device. Haptic cue algorithm using the feed-forward control algorithm is formulated to achieve optimal gear shifting in driving. Control performances are experimentally evaluated via feed-forward control strategy and presented in time domain.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.471-472
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• 2011

본 논문에서는 상 절체와 같은 급작스러운 위상천위 발생시에도 위상추정에 의한 계통연계를 위한 고속 PLL 알고리즘을 제안하였다. 제안된 고속 PLL 알고리즘은 2상 정지좌표계에서 취득한 위상정보의 불안정성을 보상하기 위함으로 저주파 필터를 이용한 정지좌표계상의 위상정보를 feed-forward로 사용한 결과, 외란에 강인한 위상각을 추정하는 알고리즘을 구현하였으며, PSIM을 이용한 시뮬레이션을 통하여 제안한 알고리즘의 타당성을 검증하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.627-632
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• 2009

This paper proposes a new haptic cue vehicle accelerator pedal device using magnetorheological (MR) brake. As a first step, an MR fluid-based haptic cue device is devised to be capable of rotary motion of accelerator pedal. Under consideration of spatial limitation, design parameters are optimally determined to maximize control torque using finite element method. The proposed haptic cue device is then manufactured and integrated with accelerator pedal. Its field-dependant torque is experimentally evaluated. Vehicle system emulating gear shifting and engine speed is constructed in virtual environment and communicated with the haptic cue device. Haptic cue algorithm using the feed-forward control algorithm is formulated to achieve optimal gear shifting in driving. Control performances are experimentally evaluated via feed-forward control strategy and presented in time domain.

• Journal of Advanced Marine Engineering and Technology
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• 제28권2호
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• pp.228-236
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• 2004

In this paper. we present a neuro-fuzzy controller which unifies both fuzzy logic and multi-layered feed forward neural networks. Fuzzy logic provides a means for converting linguistic control knowledge into control actions. On the other hand. feed forward neural networks provide salient features. such as learning and parallelism. In the proposed neuro-fuzzy controller. the parameters of membership functions in the antecedent part of fuzzy inference rules are identified by using the error back propagation algorithm as a learning rule. while the coefficients of the linear combination of input variables in the consequent part are determined by using the least square estimation method. Finally. the effectiveness of the proposed controller is verified through computer simulation for an inverted pole system.

• International Journal of Contents
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• 제8권4호
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• pp.30-35
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• 2012

Error surfaces provide us with very important information for training of feed-forward neural networks (FNNs). In this paper, we draw the contour plots of various error or objective functions for training of FNNs. Firstly, when applying FNNs to classifications, the weakness of mean-squared error is explained with the viewpoint of error contour plot. And the classification figure of merit, mean log-square error, cross-entropy error, and n-th order extension of cross-entropy error objective functions are considered for the contour plots. Also, the recently proposed target node method is explained with the viewpoint of contour plot. Based on the contour plots, we can explain characteristics of various error or objective functions when training of FNNs proceeds.