• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.680-683
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• 1999

A thyristor controlled shunt compensator, which is installed in the middle of the transmission line is adopted for controlling real power flow in a simple power transmission system. By means on the Fourier series representation of the thyristor switching action and the system parameters, the thyristor current equations are derived, which transmit the required real power of the simple power transmission system and inform the thyristor firing angle, the thyristor conduction angle, the power flows and the harmonic characteristics EMTP simulations at the various operating points show the dynamic characteristics of the thyristor controlled shunt compensator and correspond to the results calculated with the Fourier series representation.

• 전력전자학회논문지
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• 제7권3호
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• pp.237-243
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• 2002

단상 위상각제어시스템의 경우 제어기의 구조상의 단순함과 저가격화로 인해 많은 노이즈가 발생함에도 불구하고 트라이액 교류 위상각제어기를 속도제어기로 사용하고 있다. 시판되는 진공청소기의 경우 트라이액의 위상각을 조절하여 속도를 제어하고 있는데 고조파전류의 발생을 최소화로 하기 위해서 속도의 선형성을 고려하지는 않고 제작하고 있는 경우가 대부분이다. 본 논문에서는 진공청소기용 위상각 제어기에 파라미터 추정에 의한 실제작 시스템으로 고조파가 많이 발생되는 특정 트라이액 트리거 위상각에서도 고조파전류가 효과적으로 감소되고 부수적으로 지연각이 없어지는 고조파전류 감쇠용 위상제어기의 설계 및 제작하여 실험을 통해 입증하였다.

• Journal of Power Electronics
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• 제5권1호
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• pp.45-54
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• 2005

This paper presents an application of SR drives for LSEV's(Low Speed Electric Vehicles) which are used for golf and leisure. Two types of 5[HP] SRM's and its drive system are designed and tested. In order to be energy saving and have effective braking during deceleration, a multi-level inverter is proposed. For the precise switching angle control, a new type of analog encoder is proposed. A current control is adopted for soft starting and an angle control is adopted at high speed to increase efficiency. Drive characteristics and performance are shown with test results.

• Journal of Power Electronics
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• 제6권3호
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• pp.264-270
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• 2006

Magnetic levitation transfer systems are useful for transfer tools in clean rooms and positioning control systems with high precision because of frictionless characteristics. In this paper, the new method is proposed which is a sensorless position. At first, the magnetic levitation is performed by state feedback control with a disturbance observer for each of six axes of the movement of a levitated vehicle. The position of the vehicle is then estimated as the disturbance term of a disturbance observer for a pitch angle which is one of the control axes for the magnetic levitation. In addition, the positioning force is generated by the pitch angle control which gives a tilt to the levitated vehicle so that it generates the horizontal component of force.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.47-50
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• 2001

In order for effective operation of existing power systems, introduction of the so-called FACTS(Flexible AC Transmission System) such as SVC and UPFC etc, is unavoidable. The UPFC(Unified Power Flow Controller) is composed of STATCOM(Static Compensator) and SSSC(Static Synchronous Series Compensator), and is used to control the magnitude and phase angle of injected sources which are connected bothin series and in parallel with the transmission line to control the power flow and bus voltages. This paper presents a UPFC simulation on RTDS. The voltage and phase angle of a system have been analyzed by regulating the firing angle inside the UPFC.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.706-709
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• 1997

Extruders are the heart of the polymer processing industry. The single most important mechanical element of a screw extruder is the screw. The proper design of the geometriy of the extruder screw is of crucial importance to the proper functioning of the extruder. If material transport instabilities occur as a result of improper screw geometry, even the most sophisticated computerized control system cannot solve the problem. For this purpose, characteristics design on helix angle of the extruder screw. This paper presents strength of the screw flight, optimum helix angle versus dimensionless down channel pressure gradient, optimum helix angle versus the power law index in simultaneous optimization, volumetric efficiency versus helix angle at various number of flights and power consumption versus helix angle in the barrel of screw extruder.

• Journal of Power Electronics
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• 제10권3호
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• pp.300-305
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• 2010

This paper presents a two Hall sensor method for rotor angle detection in permanent magnet synchronous motors (PMSM). To minimize the implementation complexity, the system is designed to measure the edge field of permanent magnet pieces. However, there are nonlinearities in the measured values of the edge field. In this work, an angle correction algorithm is proposed, and the improvements in accuracy are verified through experiments. Finally, a field orientation controller is constructed with the proposed angle detection algorithm.

• 전력전자학회논문지
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• 제23권6호
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• pp.381-388
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• 2018

A novel and simple algorithm for accurate calculation of RMS voltage is proposed in a digitally controlled grid-tie inverter system. Given that the actual frequency of grid voltage is continuously changing, the constant sampling frequency cannot be a multiple number of the fundamental frequency. Therefore, the RMS of grid voltage contains periodic oscillations due to the differences in the phase angle of sampled data during calculation. The proposed algorithm precisely calculates and updates the initial phase angle of the first sampled voltage in a half-cycle period using phase-locked loop, which is commonly utilized for phase angle detection in grid-tie inverter systems. The accuracy and dynamic performance of the proposed algorithm are compared with those of other algorithms through various simulations and experiments.

• 전력전자학회논문지
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• 제26권4호
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• pp.298-301
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• 2021

A mechanical angle estimator is presented in this study to achieve the sensorless control of permanent magnet synchronous motor (PMSM) used in driving a reciprocating compressor. Braking the PMSM at a specific mechanical angular position is critical for the silent stoppage of the reciprocating compressor. The performance of conventional mechanical angle observers used in reciprocating compressor drives can be seriously affected according to gains of the speed controller because such observers rely on the magnitude of current ripples. A speed ripple-based mechanical angle estimator is proposed to solve this problem. Experimental results showed the effectiveness of the proposed method.

• 전력전자학회논문지
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• 제9권3호
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• pp.240-245
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• 2004

본 연구에서는 SRM의 최대 토크 운전을 위한 자기동조 제어방법을 연구하였다. SRM은 비선형적인 특성이 강하여 해석적인 방법으로 특성을 고찰하거나 속도 및 토크 제어가 어려운 단점이 있다. 따라서 본 논문에서는 최대 토크 운전을 위한 적절한 턴-온/오프각 제어를 자기동조방식(self-tuning method)에 의해 결정하는 방식을 제안하였다. 그리고 턴-온/오프각을 제어하기 위해 귀환되는 신호는 각각 엔코더 펄스수와 상전류의 증분값을 사용하였으며, 운전 중에 스스로 적절한 턴-오프각을 먼저 추종하고 다음으로 턴-온각을 추종하게 된다. 턴-온/오프각은 서로 종속적인 관계에 있으므로 최대 토크 값을 유지하기 위한 턴-온/오프각을 실시간 자기동조방식으로 제어하였으며, 실험을 통해 제안된 방식이 타당함을 확인하였다.