• 한국정밀공학회지
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• 제17권10호
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• pp.162-169
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• 2000

A Direct Drive Valve(DDV) hydraulic actuation system which is commonly used as an aircraft's control surface driving actuator has multi-loop control structure to ensure its safety operation. However, because of not perfect matching of one self channel characteristics with the others, the servo valve driving current of each channel can be widely different. Therefore, the long-time use of DDV actuator without any correction of these channel current offsets will cause the problem of performance or life expectancy degradation due to unwanted heats in the linear motor. A current equalization loop structure which can minimizes current offsets between channels is introduced and designed. The performance of the current equalization loop is investigated and verified through the analytic and experimental ways.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.143-145
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• 2009

The method for the current equalization of the rectifier diodes in LLC resonant converter is proposed. The method decreases the current difference between the rectifier diodes using the auxiliary winding of the transformer and asymmetrical pulse width modulation (APWM). The analytical reason of the current unbalance is investigated and the operation principle of the proposed method and APWM control loop are explained. The performance of the proposed method was verified on a 480-W, 400-V/24-V dc/dc converter.

• Journal of Power Electronics
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• 제8권3호
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• pp.217-227
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• 2008

The electric power subsystems (EPS) of most remote sensing satellites consist of a solar array as a source of energy, a storage battery, a power management and control (PMC) unit and a charge equalization unit (CEU) for the storage battery. The PMC and CEU use high frequency transformers in their power modules. This paper presents a design, implementation and testing results of a high frequency transformer for the EPS of satellite applications. Two approaches are used in the design process of the transformer based on the pre-determined transformer specifications. The transformer is designed based on an ETD 29 ferrite core. The implemented transformer consists of one center-tapped primary coil with eleven center-tapped secondary coils. The offline calculation results and measured values of R, L for transformer coils are convergence. A test circuit for measuring the transformer parameters like voltage, current and B-H hysteresis was implemented and applied. The test results confirm that the voltage waveforms of both primary and secondary coils were as desired. No overlapping occurred between the control signal and the transformer, which was not saturated during testing even during a short circuit test of the secondary channels. The dynamic B-H loop characteristics of the used transformer cores were measured. The sample test results are given in this paper.

• 한국항공우주학회지
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• 제34권3호
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• pp.74-80
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• 2006

본 논문은 선형 전기모터가 유압밸브 스풀(valve spool)을 직접 움직이는 직접구동밸브 (DDV: direct drive valve) 방식 유압서보 엑츄에이터의 제어 및 고장 모니터링에 관한 것이다. 유압서보 구동장치는 밸브 스풀을 통한 유량 흐름 특성으로 인하여 비선형 운동 특성을 갖게 된다. DDV 구동장치에 관한 비선형 운동 모델을 제시하고, 이를 선형화 시켜 DDV 구동장치의 제어계 및 고장 감지계 설계에 유용하게 사용될 수 있는 단순화된 선형 모델을 제시하였다. 한편, 조종면 구동 엑츄에이터가 만족시켜야 하는 성능 그리고 안전 작동에 관한 요구조건에 대하여 논의한 후, 이를 만족시키기 위한 제어계 및 고장 감지계의 구조에 대한 논의를 한다. 3중의 다중화 구조를 갖는 유압 DDV 구동장치의 운동 특성을 해석할 수 있는 수치해석 모델이 개발되었다.