• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.369-372
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• 1994

In this paper, a voltage type dual PWM converter which achives the bidirectional power flow between a AC supply and a DC bus voltage is described. In PWM modulator, there exist a time difference between the sampling time and carrier wave, it achieves stable modulation even the disturbance in the synchronous AC source voltage. And this paper proposes the compensation method and the control method related a disturbance of synchronous signal using the low pass filter and phase shifter for the stable modulation. As a result the voltage type dual PWM converter makes the imput current wave as sinusoid, and performs the high power factor driving.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.444-446
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• 2005

This paper describes a current differential relaying algorithm for power transformers with an advanced compensation algorithm for the secondary current of CTs. The comparative study was conducted with and without the compensating algorithm. The algorithm can reduce the operating time of the relay in the case of an internal fault and improve security for external faults. The performance of the proposed algorithm was investigated when the C100 CT, a quarter of the rated CT(C400), is used.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.52-55
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• 1996

In order to establish the robust current controller design technique of series wound motor driver system. This paper proposes a method of compensated Bang-Bang current control using a series wound motor driver system under improperly variable load. To get minimum time torque control. A compensated Bang-Bang current controller structure is simpler than the structure of PID plus Bang-Bang controller. This paper shows that a general 8 bits microprocessor be used efficiently implementing such an algorithm. The calculation time of software is extremely small when compared with conventional PID plus Bang-Bang a controller. Both nonlinear operating characteristics of Digital switching elements and Describing Function methods are used for the analysis and synthesis. Real time implementation of compensated Bang-Bang current is achieved. Concept design strategy of the control and PWM waveform generation algorithms are presented in the paper.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.66-69
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• 2008

In this paper, The author present a load current feed-forward compensator by method that improve voltage controller of Step-down Chopper to get stable output voltage to sudden change of load current. To confirm the characteristicsof a presented load current feed -forward compensator compared each transfer function of whole system that load current feed-forward compensator is added with transfer function of whole system that existent voltage controller is included using Mason gains formula in Root locus and Bode diagram. As a result the pole of system is improved, extreme point of the wave and system improves, and size of peak value and phase margin of break frequency in resonance frequency confirmed that is good. Therefore, presented control technique could confirm that reduce influence by perturbation and improves stationary state and dynamic characteristics in output of Step-down Chopper.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.447-454
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• 1998

This paper describes a modeling and current control techniques of Distribution static condenser (D-STATCON) for power factor compensation. The current control is based on the predictive and the space vector PWM scheme. The predictive current controlled PWM D-STATCON can maintain its performance with power factor compensation and fixed switching frequency. By using the space vector control low ripple and offset in the current and the voltage as well as fast dynamic responses are achieved with a small DC link capacitance employed.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.324-329
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• 2017

The phase controlled rectifier using thyristor is suitable for the high capacity and low-cost system. However, the rectifier output voltage drop is influenced by the grid inductance effect. Supposing the commutation area voltage and current are analyzed, the grid inductance can be estimated using the proposed algorithm. This paper presents the grid inductance estimation method for improved commutation compensation control of the phase controlled rectifier, and the proposed control algorithm effectiveness is verified by simulation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.6
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• pp.330-335
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• 1999

This paper proposed the p-q-r coordinate system where the instantaneous active power p, and the two instantaneous reactive powers qq, qr were defined. The three power components are linearly independent, so the compensation for the two instantaneous reactive powers leads to control the two components of the current space vector. With the theory, the neutral current of a three-phase four-wire system can be eliminated by only compensating the instantaneous reactive power using no energy storge element.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.144-145
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• 2017

서보 시스템에서는 물리적인 제한조건을 반영하여 위치 프로파일을 그려왔다. 하지만 위치 프로파일이 종료된 시점 남아있는 오차를 기존의 오차 기반 제어기를 이용하여 수렴시키기엔 많은 시간이 소요되고 이는 위치제어 성능 문제로 직결된다. 본 논문에서는 기존의 프로파일이 끝난 시점에서 시스템 제한을 고려한 최대 전압과 최대 전류를 이용하는 프로파일을 연속적으로 그려 수렴구간을 단축시키는 방법을 제안한다. 1kW 용량 서보모터를 통해 수렴시간을 기존 프로파일 방식과 비교하여 알고리즘을 검증하였다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.116-117
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• 2014

본 논문에서는 3상 IPM을 사용하여 2상 유도전동기를 위한 2레그형 인버터를 설계하였다. 3상 IPM은 6개의 스위칭 소자를 내장하고 있어서 이중 4개는 2레그형 인버터로 사용하고, 나머지 2개는 역률제어 회로에 이용할 수 있다. 이렇게 하면 하드웨어의 추가를 최소화하면서 역률제어 기능을 갖는 2레그형 인버터를 구현할 수 있다. 2레그형 인버터에서는 반드시 직류링크에 2개의 커패시터를 직렬로 연결하는데, 입력 전원의 반주기 마다 각각의 커패시터에 충방전 동작이 수행된다. 이러한 동작으로 인해 2개의 커패시터에 전압 불균형이 발생할 수 있고 커패시터 용량이 서로 다를 경우에는 이 전압 리플이 더욱 커지게 되며, 이것은 전동기에 불평형 전류를 공급하게 되어 전동기의 토크리플을 발생시킨다. 본 논문에서는 직류링크의 전압 불균형 문제가 전동기에 미치는 영향을 분석하고, 이러한 전압 불균형을 보상하여 전동기의 토크리플을 제거하고 동작특성을 개선하는 방법을 제안하며, 컴퓨터 시뮬레이션을 통하여 이를 검증한다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.480-481
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• 2012

본 논문에서는 태양광 발전 시스템에서 발생하는 저차 고조파를 저감하는 기법을 제안한다. 태양광 발전 시스템에 포함된 단상 인버터는 기본파의 2배 주파수를 가지는 2차 고조파를 만들어낸다. 이 저차 고조파는 컨버터 전류의 리플로 작용하여 태양전지의 출력을 최대로 높이는 최대전력점 추종기법의 효율을 저감시킨다. 본 논문에서는 계통연계형 태양광 발전 시스템에서 발생하는 저차 고조파를 분석한다. 그리고 추가적인 하드웨어 소자 없이 비례공진 제어기를 사용한 새로운 전향보상 성분을 통해 효과적으로 제거한다. 제안된 알고리즘은 시뮬레이션을 바탕으로 타당성을 검증한다.