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300V DC Feed System for Internet Data Center
Du-Hwan Kim,Taesik Yu,Hyosung Kim,Hyungsoo Mok,Kyung-Seok Park 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Internet Data Centers (IDC), as essential facilities for modern IT industry, typically have scores of ㎿ of concentrated electric loads. Uninterruptible Power Supplies (UPS) are necessary for the power feed system of IDCs because of stable power requirement. Thus, conventional AC power feed systems of IDCs have three cascaded power conversion stages such as (AC-DC), (DCAC), and (AC-DC), which results in very low conversion efficiency. On the contrary, DC power feed systems need just a single power conversion stage (AC-DC) supplying AC mains power to DC server loads, which gives comparatively high conversion efficiency and reliability [5]. This paper compares the efficiencies between 220V AC power feed system and 300V DC power feed system on equal load conditions which were established in Mok-Dong IDC of Korea Telecom Co. Ltd. (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is around 15% higher than that of the 220V AC power feed system.
Analysis of the Admittance Component for Digitally Controlled Single-Phase Bridgeless PFC Converter
Younghoon Cho,Hyungsoo Mok,Jih-Sheng Lai 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.4
This paper analyzes the effect of the admittance component for the digitally controlled single-phase bridgeless power factor correction (PFC) converter. To do this, it is shown how the digital delay effects such as the digital pulse-width modulation (DPWM) and the computation delays restrict the bandwidth of the converter. After that, the admittance effect of the entire digital control system is analyzed when the bridgeless PFC converter which has the limited bandwidth is connected to the grid. From this, the waveform distortion of the input current is explained and the compensation method for the admittance component is suggested to improve the quality of the input current. Both the simulations and the experiments are performed to verify the analyses taken in this paper for the 1 kW bridgeless PFC converter prototype.
Digital Control Strategy for Single-phase Voltage-Doubler Boost Rectifiers
Younghoon Cho,Hyungsoo Mok,Jun-Keun Ji,Jih-Sheng Lai 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4
In this paper, a digital controller design procedure is presented for single-phase voltage-doubler boost rectifiers (VDBR). The model derivation of the single-phase VDBR is performed in the s-domain. After that the simplified equivalent z-domain models are derived. These z-domain models are utilized to design the input current and the output dc-link voltage controllers. For the controller design in the z-domain, the traditional K-factor method is modified by considering the nature of the digital controller. The frequency pre-warping and anti-windup techniques are adapted for the controller design. By using the proposed method, the phase margin and the control bandwidth are accurately achieved as required by controller designers in a practical frequency range. The proposed method is applied to a 2.5 kVA single-phase VDBR for Uninterruptible Power Supply (UPS) applications. From the simulation and the experimental results, the effectiveness of the proposed design method has been verified.
Analysis of the Admittance Component for Digitally Controlled Single-Phase Bridgeless PFC Converter
Cho, Younghoon,Mok, Hyungsoo,Lai, Jih-Sheng The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.4
This paper analyzes the effect of the admittance component for the digitally controlled single-phase bridgeless power factor correction (PFC) converter. To do this, it is shown how the digital delay effects such as the digital pulse-width modulation (DPWM) and the computation delays restrict the bandwidth of the converter. After that, the admittance effect of the entire digital control system is analyzed when the bridgeless PFC converter which has the limited bandwidth is connected to the grid. From this, the waveform distortion of the input current is explained and the compensation method for the admittance component is suggested to improve the quality of the input current. Both the simulations and the experiments are performed to verify the analyses taken in this paper for the 1 kW bridgeless PFC converter prototype.
RecurDyn과 Matlab/Simulink를 이용한 전동지게차 시스템의 Co-Simulation
김상훈(Sanghoon Kim),목형수(Hyungsoo Mok),윤덕진(Dukjin Yun) 전력전자학회 2006 전력전자학술대회 논문집 Vol.- No.-
전동기 구동시스템의 사양 결정과 설계를 위해서는 부하의 부하토크, 관성계수, 마찰계수 등의 정보에 의한 부하 모델링이 반드시 필요하다. 전동지게차 시스템의 모델링을 위해서는 차체의 중량과, 바퀴의 제원 등 제한적인 정보를 기초로 하여 번거로운 계산과정을 거쳐야 하지만 정확한 정보를 얻기에는 어려움이 따른다. RecurDyn은 기계시스템의 모델링과 시뮬레이션을 하는 3차원 해석이 가능한 Functionbay사에서 개발한 시뮬레이션 프로그램으로서 3D의 기계적인 형상을 작성하고, 물성을 입력하면 부하토크, 등가 관성계수, 마찰계수를 출력할 수 있어 전동기구동시스템의 시뮬레이션 프로그램인 Matlab/Simulink와 결합하여 시뮬레이션을 수행 할 경우 부하 모델링 없이 전체 구동시스템의 특성 시뮬레이션이 가능하다. 본 논문에서는 영구자석 동기전동기로 구동하는 전동지게차 시스템을 대상으로 RecurDyn 프로그램의 활용을 소개하고 Matlab/Simulink를 이용한 결함 시뮬레이션의 가능성을 보고자 한다.
단일 전류 센서를 이용한 2상 하프브릿지 인버터의 상전류 측정 방법
조영훈(Younghoon Cho),목형수(Hyungsoo Mok),장도현(Dohyun Jang),김상훈(Sanghoon Kim) 전력전자학회 2007 전력전자학술대회 논문집 Vol.- No.-
This paper proposed a novel current measurement method for two-phase half-bridge inverter using single current sensor. The proposed method measures DC link input current and a phase current simultaneously and reconstructs each phase currents by simple calculation according to voltage vector. The commutation modes of two-phase half-bridge inverter is analized. The current sampling and reconstructing method is also presented. The proposed method is verified through simulation and experimental results on two-phase induction motor drive system.