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전류 리플을 이용한 직류단 캐패시터의 용량 선정 기법에 관한 연구
김용휴,이병훈,황선환 한국산업융합학회 2022 한국산업융합학회 논문집 Vol.25 No.1
This paper proposes a method for selecting the capacitance of DC-link capacitors of inverters. In general, the DC-link capacitance of the inverter system must be considered for DC-link voltage, ripple current, switching frequency, ripple voltage, and pulse-width modulation techniques. Therefore, the appropriate capacitance can be determined by finding the rms and peak values of the ripple current of the capacitor. In this paper, the process of extracting the ripple current of DC-link capacitor is described in detail. In addition, the simple method for finding DC-link capacitor capacitance using the result value is presented through the simulations.
김용휴(Yong-Hyu Kim),박성준(Sung-Jun Park),정준형(Jun-Hyung Jung),김동윤(Dong-Youn Kim),김장목(Jang-Mok Kim) 전력전자학회 2015 전력전자학회 논문지 Vol.20 No.2
This paper proposes a regeneration braking algorithm for Brushless DC (BLDC) motor system. The unipolar switching method has a limitation about the regeneration braking when the BLDC motor is operated in the low speed region. The proposed algorithm alternatively utilizes the unipolar and bipolar switching method to implement the regeneration braking for overall speed range. The bipolar switching method is used when the BLDC motor is operated in the low speed region. The switching transition point is determined by analyzing the unipolar and bipolar switching during the regeneration braking. The effectiveness of proposed algorithm is verified by using the experimental results.
토사지반과 핵석이 포함된 복합지반에서 쉴드TBM 굴진 시 장비부하에 관한 연구
김기환,김혁,문철화,김용휴,김동호,이재용 사단법인 한국터널지하공간학회 2018 한국터널지하공간학회논문집 Vol.20 No.6
도심지 터널공사에서는 주변 건물의 안전성을 확보하고, 민원을 최소화할 수 있는 쉴드TBM 공법이 대부분 적용되고 있다. 도심지에는 기존의 택지를 매립조성하거나 개량하는 경우가 많기 때문에 지표에서부터 암반 경계부까지는 불균질한상태로 이루어지는 경우가 많다. 이와 같이 토사지반, 파쇄정도가 다양한 화강암지반, 핵석층, 암층과 같이 복잡한 지반조건에서 쉴드TBM으로 터널구조물을 구축하는 경우, 각 지반조건에 따른 쉴드TBM에 나타나는 기계데이터를 분석하여 지반조건에 따른 장비부하의 특징을 비교분석하였다. 그 결과, 설계막장압을 유지하면서 굴진하고, 주기적으로 커터를 점검하여 교체하는 경우, 배토량, 추력, 커터토오크의 경향으로 지반조건의 변화를 예측할 수 있을 것으로 판단된다. In urban tunnel construction, most of the Shield TBM method is applied to secure the safety of buildings and to minimize risks. On the other hand, in the urban development process, landfills are often embanked or improving in many cases, so that the boundary between the surface and the rock is often heterogeneous. In case of ground condition such as alluvial soil, granite, decomposed granite, core stone and rock with various layers, datas on shield TBM advancing according to each ground condition are analyzed, The characteristics of machine load were compared and analyzed. As a result, it can be predicted that the change of ground condition can be predicted by the tendency of discharge volume, thrust force and cutting wheel torque when the cutter is checked and replaced regularly on advancing under maintaining the design slurry pressure.
Capacitance Estimation Method of DC-Link Capacitors for BLDC Motor Drive Systems
문종주,김장목,박준호,김용휴 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.3
This paper proposes a capacitance estimation method of the dc-link capacitor for brushless DC motor (BLDCM) drive systems. In order to estimate the dc-link capacitance, the BLDCM is operated in quadrant-II or -IV among four-quadrant operation. Quadrant-II and -IV are called reverse braking and forward braking, respectively. During the braking operation of the BLDCM, the capacitor is charged by the phase current and then the voltage is increased during the braking operation time. The capacitor current and voltage can be obtained by using the phase current sensor of BLDCM and the dc-link voltage sensor. The capacitance and be easily obtained by the voltage equation of the capacitor. The proposed method guarantees the reliable and simple calculation of the dc-link capacitance without additional hardware system except several the sensors already installed for the motor control system. The effectiveness of the proposed method is verified through both the simulation and experimental results.
장용채(Chang Yongchai),김용휴(Kim Yonghyu),이승은(Lee Seungeun),박기철(Park Kichul),노진숙(No Jinsuk) 한국지반환경공학회 2009 한국지반환경공학회논문집 Vol.10 No.4
표준사로 형성된 지반 10㎝아래에 연성관을 매설하여 각각의 상대밀도에서 지반거동에 따른 관의 변형을 관찰을 하였다. 지반보강 상태에서의 관의 거동을 파악하기 위하여 지오그리드를 매설관 하부에 설치한 후 각각 지반에서의 관의 변형을 관찰하였다. 관아래 지오그리드를 설치한 후 보강된 지반의 관 변형형태를 관찰하였다. 지오그리드로 보강한 지반은 수직하중이 높아질수록 보강재에 인장력이 형성되어 보강유무에 따른 동일한 수직하중에서 침하가 감소하였다. 상대밀도 100%지반과 70%지반 변형분포가 차이가 나타났다. 보강 70%지반에서는 최종침하 100㎜일 때 무보강 100%지반의 최종침하에서의 지반반력에 가깝게 수렴 하였다. 매설관의 하부 변형 형태에서도 무보강 100%지반의 매설관 변형 형태와 유사한 것으로 보아 연약지반에서 지오그리드의 보강효과가 기대된다. A flexible pipe was buried 10cm below the ground formed with standard sand to observe changes in the shape of the pipe according to the behavior of ground at each relative density. Changes in the shape of the pipe in each ground were observed to examine the behavior of the pipe under the state of reinforced ground after installing geogrid under the pipe. Ground reinforced using geogrid formed tensile force on the reinforcement material with increase in the vertical load and showed reduction in settlement under identical vertical load with existence of reinforcement. Distributions of ground deformation of 100% relative density and 70% relative density had clear difference. Reinforced ground with 70% density converged to the ground reaction of final settlement of non-reinforced ground with 100% density at final settlement of 100 mm. Because the shape of lower part strain of the buried pipe is similar to that of un-reinforced ground with relative density of 100%, reinforcement effect by geogrid in soft ground can be anticipated.
단상 영구자석 동기 전동기의 비대칭 공극 구조를 고려한 회전자 초기 자극 검출 기법
서승우,황선환,박종원,김용휴,Seo, Sung-Woo,Hwang, Seon-Hwan,Park, Jong-Won,Kim, Yong-Hyu 전력전자학회 2022 전력전자학회지 Vol.27 No.1
This paper proposes an initial rotor polarity detection algorithm of a single-phase permanent magnet synchronous motor (SP-PMSM) related to stable open-loop starting for sensorless operation. Generally, the SP-PMSM needs an asymmetric air-gap structure to can avoid the initial starting failure at zero torque point. Therefore, the rotor polarity information can be obtained by using the DC offset current direction of a stator current through a high frequency voltage injection into an SP-PMSM with an asymmetric air gap. In this paper, the proposed rotor initial polarity detection algorithm is verified through several experimental results.
단상 영구자석 동기 전동기의 비대칭 공극 구조를 고려한 회전자 초기 자극 검출 기법
서승우,황선환,박종원,김용휴 전력전자학회 2022 전력전자학회 논문지 Vol.27 No.1
This paper proposes an initial rotor polarity detection algorithm of a single-phase permanent magnet synchronous motor (SP-PMSM) related to stable open-loop starting for sensorless operation. Generally, the SP-PMSM needs an asymmetric air-gap structure to can avoid the initial starting failure at zero torque point. Therefore, the rotor polarity information can be obtained by using the DC offset current direction of a stator current through a high frequency voltage injection into an SP-PMSM with an asymmetric air gap. In this paper, the proposed rotor initial polarity detection algorithm is verified through several experimental results.