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Estimation of High-Frequency Parameters of AC Machine From Transmission Line Model
Younggon Ryu,Bo-Ryang Park,Ki Jin Han IEEE 2015 IEEE transactions on magnetics Vol.51 No.3
<P>This paper proposes a modeling method to estimate the high frequency (HF) characteristics of stator winding in an ac machine. From the frequency response of windings, the proposed method extracts frequency-dependent per-unit-length (PUL) transmission line parameters, which are simplified to a PUL equivalent circuit, including low-frequency and HF components. The newly developed PUL circuit provides a simple distributed-element winding model that captures HF behaviors accurately, and the modeling procedure can be easily adopted for an initial design with simulation data. To verify the proposed method, input impedance from a constructed equivalent circuit of an induction machine was compared with the measurement results. In addition, the concept of effective length, which is involved with antiresonance phenomena, is presented based on the proposed method.</P>
Common Mode Noise Reduction for an LLC Resonant Converter by Using Passive Noise Cancellation
Younggon Ryu,Sungnam Kim,Geunseok Jeong,Jaesu Park,Duil Kim,Jongwook Park,Jingook Kim,Ki Jin Han 한국전자파학회JEES 2015 Journal of Electromagnetic Engineering and Science Vol.15 No.2
This paper describes the application of a passive noise cancellation method to a prototype inductor-inductor-capacitor (LLC) resonant converter by placing a compensation winding in a transformer to reduce common mode noise. The connection method for the compensation winding is investigated. A circuit analysis is implemented for the displacement currents between the primary and secondary windings in the transformer. The analyzed displacement currents are verified by performing a circuit simulation and a proper compensation winding connection that reduces common mode noise is found. The measurement results show that common mode noise is reduced effectively up to 20 dB in the 1 to 7 MHz frequency region for the prototype LLC resonant converter by using the proposed passive noise cancellation method.
Park, Hwa-Pyeong,Ryu, Younggon,Han, Ki Jin,Jung, Jee-Hoon The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.2
This paper proposes the design considerations of resonant network and transformer magnetics for 500 kHz high switching frequency LLC resonant converter. The high power density can be effectively achieved by adopting high switching frequency which allows small size passive components in the converter. The design methodology of magnetizing inductance is derived for zero voltage switching (ZVS) condition, and the design methodology of the transformer and output capacitance is derived to achieve high power density at high operating frequency. Moreover, the structure of transformer is analyzed to obtain the proper inductance value for high switching operation. To verify the proposed design methodology, simulation and experimental results will be presented including temperature of passive and active components, and power conversion efficiency to evaluate dominant power loss. In addition, the validity of magnetics design will be evaluated with operating waveforms of the prototype converter.
Hwa-Pyeong Park,Younggon Ryu,Ki Jin Han,Jee-Hoon Jung 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.2
This paper proposes the design considerations of resonant network and transformer magnetics for 500 kHz high switching frequency LLC resonant converter. The high power density can be effectively achieved by adopting high switching frequency which allows small size passive components in the converter. The design methodology of magnetizing inductance is derived for zero voltage switching (ZVS) condition, and the design methodology of the transformer and output capacitance is derived to achieve high power density at high operating frequency. Moreover, the structure of transformer is analyzed to obtain the proper inductance value for high switching operation. To verify the proposed design methodology, simulation and experimental results will be presented including temperature of passive and active components, and power conversion efficiency to evaluate dominant power loss. In addition, the validity of magnetics design will be evaluated with operating waveforms of the prototype converter.
이동헌(Donghun Lee),홍창열(Changyoul Hong),김영곤(Younggon Kim),유양우(Yangwoo Ryu),박성진(Seongjin Park),이명준(Myungjoon Lee) 한국정보과학회 1998 정보과학회 컴퓨팅의 실제 논문지 Vol.4 No.4
CORBA는 OMG에서 개방 분산 객체 컴퓨팅의 표준으로 제시한 하부구조이며, 이기종의 컴퓨터 시스템으로 구성된 계산 환경에서 분산 객체들간의 상호 운용성을 보장한다. 본 논문에서는, Ada95를 이용하여 개발 중인 ReCA(a Reliable CORBA system using Ada95) CORBA 시스템의 핵심 부분인 ORB의 설계및 구현에 대하여 기술한다. ReCA ORB의 주요 구성요소에는 기반 통신 계층, ORB core, BOA가 있다. ReCA ORB의 기반 통신 계층은 하부 통신 시스템에 독립적인 VOOL(Virtual Object-Oriented Low-level) 계층과 VOOL 상에서 ORB들 간의 메시지 전송을 위해 이용되는 RMC(Remote Method Call) 계층으로 구성된다. 객체 요청간의 동기화와 병행성의 조작을 위해서 ReCA BOA는 보호 객체와 태스크풀과 같은 Ada95의 병행성 기능을 이용하여 ReCA ORB가 안정적이면서도 효율적으로 다중 객체 요청을 다룰 수 있도록 한다. COREA is an open distributed object computing infrastructure standardized by the OMG and guarantees interoperability between distributed objects in the computing environment composed of heterogeneous computer systems. In this paper, we describe a design and implementation of ReCA(a Reliable CORBA system using Ada95) ORB which is the core part of ReCA CORBA system being developed in Ada95. Major components of ReCA ORB are a fundamental communication layer, ORB core, and BOA. The fundamental communication layer of ReCA ORB consists of a VOOL(Virtual Object-Oriented Low-level) layer which is independent of low-level communication subsystems, and a RMC(Remote Method Call) layer which is used for passing messages between ORBs over the VOOL layer. For synchronization and concurrency control between object requests, ReCA BOA uses the concurrency features in Ada95 such as protected objects and task pools, which enable the ReCA ORB to handle multiple object requests both reliably and efficiently.