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T-type 3-레벨 PWM 컨버터의 중성점 전류 분석
이귀준 전력전자학회 2020 전력전자학회 논문지 Vol.25 No.1
As a T-type three-level PWM converter has several intrinsic advantages, it has been widely studied for many applications. However, it requires an additional voltage control loop for balancing each DC link voltage. Generally, satisfying this requirement involves the use of an offset voltage to provide a neutral point current without affecting other variables, such as the total DC link voltage and three-phase input current. In this study, the theoretical relationship between the offset voltage and the neutral point current is analyzed. The results can be beneficial for effective voltage balancing controller design. The effectiveness of the analytical modeling is verified by simulation and experimental results.
계통연계형 인버터에서 대칭 구조를 갖는 LCL 필터 설계 및 제어
이귀준(Kui-Jun Lee),박남주(Nam-Ju Park),현동석(Dong-Seok Hyun) 전력전자학회 2008 전력전자학술대회 논문집 Vol.- No.-
An inductor-capacitor-inductor (LCL) filter are widely adapted in grid-connected inverter applications. In this paper, the harmonic attenuations of the LCL filter are quantitatively analyzed, and then the design optimization of two inductance values, which are related on a cost and a size, is illustrated. Based on the design optimization, the LCL filter employing a Symmetric Geometry is proposed. Through the equivalent circuit analysis of the proposed LCL filter, the operating characteristics and validity are presented in detail. In addition, simple proportional-integral (PI) current controller suitable for the LCL Filter is designed to mitigate the resonance problem. From simulation results, it is seen that the proposed LCL filter and control method have a sufficient attenuation and stability for the high frequency distortions and load variations.
LCL 필터를 갖는 3상 계통연계형 인버터의 최적 전류 제어
이귀준(Kui-Jun Lee),박남주(Nam-Ju Park),현동석(Dong-Seok Hyun) 전력전자학회 2007 전력전자학술대회 논문집 Vol.- No.-
This paper presents a robust current control in a three phase grid connected inverter using an LCL filter. This controller is based on the optimal control theory and typically designed in a complex-valued state-space. The proposed current controller has a robust tracking performance for the grid voltage harmonics and robustness to parameter error and load variation. Finally, the simulation results are presented to verify the validity of the proposed method.
리튬-이온 배터리 충방전 균등화를 위한 3-단자 양방향 모듈 회로
이귀준(Kui-Jun Lee),박남주(Nam-Ju Park),왕웅비(Xiongfei Wang),현동석(Dong-Seok Hyun) 전력전자학회 2008 전력전자학술대회 논문집 Vol.- No.-
In this paper, a three-port bidirectional modular circuit applied in charging and discharging equalization for lithium-ion battery strings is proposed. This circuit consists of four MOSFETs and one transformer which provide a simple structure to be easily modularized. Compared to conventional individual cell equalization schemes, it utilizes the transformer as the energy transfer element, allowing direct transfer of energy between arbitrary two cells of three-cell battery module, thus improving the equalization efficiency significantly by using much less number of equalizers for long battery strings. Simulation results are presented to validate the circuit operation and confirm its capability to equalize the three-cell battery module.
SRM 구동용 전압형 인버터의 간단한 고장 검출 및 보상 기법
이귀준(Kui-Jun Lee),박남주(Nam-Ju Park),현동석(Dong-Seok Hyun) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-
SRM has magnetic independence of the motor phases, so that it possesses fault tolerant characteristics and is applied to the applications requiring high reliability, such as aircraft. However, SRM driver which satisfies tolerant systems to compensate performance deterioration and ensure safety are of extreme importance. In this paper, simple and fast fault detection scheme using voltage sensor in each phase lower switches is proposed in faulty mode. The validity of the proposed method is verified by simulation.