• 전기학회논문지P
• /
• 제58권4호
• /
• pp.397-403
• /
• 2009

In this paper, an exciter current control of a synchronous generator for ships using a compound type digital automatic voltage regulator (DVAR) in order to provide a constant output voltage of the generator is presented. The compound type DAVR is composed of a controller part to adjust output voltage and an power source unit to supply power to the exciter. The controller part, which generates the PWM switching pattern via the PI controller, drives a power MOSFET for bypass to limit the SG's exciter current. The power source unit part is parallel connected to an output terminal of the generator through a reactor and a power CT. The residual magnetic flux of SG provides exciter current to the exciter through the reactor during the initial running or no load state and load current supplies field current to the exciter through the power CT during loading state. This paper confirmed an experiment to verify the validity of compound type DAVR system for controlling output voltage of synchronous generator.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
• /
• pp.1-5
• /
• 2004

This paper describe a control scheme for direct torque control of BLDC Motor. The proposed Luenberger Observer scheme calculate flux errors in order to control the torque and flux more correctly. This proposed control scheme has not the requirement of a separate current regulator and proportional-integral (PI) control of the flux and torque, there by improving transient performance and also has the advantage of less torque ripple in steady state with a fixed switching period. The effect of proposed method has been proven by simulations.

• Journal of Power Electronics
• /
• 제19권6호
• /
• pp.1403-1412
• /
• 2019

A coupled inductor-dual boost-inverter (CIDBI) with a differential structure has been presented for application to a micro-inverter photovoltaic module system due to its turn ratio of a high-voltage level. However, it is difficult to design a CIDBI converter with a conventional PI regulator to be stable and achieve good dynamic performance, given the fact that it is a high order system. In view of this situation, a sliding mode control (SMC) strategy is introduced in this paper, and two different sliding mode controllers (SMCs) are proposed and adopted in the left and right side of two Boost sub-circuits to implement the corresponding regulation of the voltage and current. The schemes of the SMCs have been elaborated in this paper including the establishment of a system variable structure model, selection of the sliding surface, determination of the control law, and presentation of the reaching conditions and sliding domain. Finally, the mathematic analysis and the proposed SMC are verified by experimental results.

• 전력전자학회논문지
• /
• 제4권5호
• /
• pp.462-473
• /
• 1999

디지털 제어 방식으로 구동되는 모든 교류 전동기 벡터제어시스템의 근간을 이루는 전류 측정에 관한 문제를 다룬다. 일반적인 펄스폭 변조 방식 교류 전동기 구동 시스템에서 전동기 전류에 포함된 인버터 스위칭 노이즈를 없애기 위하여 저역 통과 필터를 사용하는데 이러한 필터는 필연적으로 측정된 신호의 시간 지연을 유발하게 된다. 따라서 샘플링한 전류값에는 기본파 성분 뿐만아니라 고조파 리플 성분이 포함된다. 본 논문에서는 3상 대칭 펄스폭 변조시 기준 전압 벡터의 위치에 다른 전류 샘플링 오차를 해석적으로 구하고 이러한 샘플링 오차를 최소화하기 위한 기법을 제안한다. 제안된 지연 보상 샘플링 기법을 사용하면 정상 상태 전류 측정 오차를 최소화할 수 있고 보다 정확한 토오크 제어가 가능하게 됨을 시뮬레이션과 실험을 통해 보였다.

• 로봇학회논문지
• /
• 제17권3호
• /
• pp.308-313
• /
• 2022

This paper proposes a velocity control method for a permanent magnet synchronous motor (PMSM) based on the Koopman operator that does not require model parameter information except for pole-pair of the motor and external load. First, the Koopman operator is derived using observable functions and observation data. Then, the desired q-axis current corresponding to the desired velocity is generated using the relationship between the continuous-time Koopman operator and the dynamics of PMSM. Also, the dynamic equation of PMSM is expressed as a linear form in observable space using the discrete-time Koopman operator. Finally, it is applied to the linear quadratic regulator (LQR) to derive the final form of control input. To verify the proposed method, the conventional cascade PI controller and the LQR controller configured with the existing technique are compared with the proposed method in the viewpoint of q-axis current generation and velocity tracking performance in an environment with noise and external load.

• 전력전자학회논문지
• /
• 제11권2호
• /
• pp.127-134
• /
• 2006

고성능 DSP 또는 마이크로프로세서를 통해 구현되던 벡터제어를 프로그램이 가능한 소자인 FPGA를 통해 하드웨어로 구현하였다. 이를 위해 벡터제어 알고리즘을 구성하는 제어 블록들을 VHDL을 통해 모듈화 하고, 모듈화한 벡터제어 알고리즘을 FPGA에 프로그래밍 하여 하드웨어 벡터제어기를 구현하였다. 그리고 하드웨어 벡터제어기의 성능을 검증하기 위해 영구자석 동기 전동기 구동을 위한 벡터제어 시스템을 구성하고, 소프트웨어 기반 벡터제어 시스템과 벡터제어 알고리즘 연산시간 및 성능에 대한 비교연구를 수행하였다.

• Asian Pacific Journal of Cancer Prevention
• /
• 제15권16호
• /
• pp.6463-6475
• /
• 2014

The mammalian target of rapamycin (mTOR) kinase plays an important role in regulating cell growth and cell cycle progression in response to cellular signals. It is a key regulator of cell proliferation and many upstream activators and downstream effectors of mTOR are known to be deregulated in various types of cancers. Since the mTOR signalling pathway is commonly activated in human cancers, many researchers are actively developing inhibitors that target key components in the pathway and some of these drugs are already on the market. Numerous preclinical investigations have also suggested that some herbs and natural phytochemicals, such as curcumin, resveratrol, timosaponin III, gallic acid, diosgenin, pomegranate, epigallocatechin gallate (EGCC), genistein and 3,3'-diindolylmethane inhibit the mTOR pathway either directly or indirectly. Some of these natural compounds are also in the clinical trial stage. In this review, the potential anti-cancer and chemopreventive activities and the current status of clinical trials of these phytochemicals are discussed.

• Asian Pacific Journal of Cancer Prevention
• /
• 제13권12호
• /
• pp.6139-6144
• /
• 2012

Aims: Mammalian target of rapamycin (mTOR) is master regulator of the PI3K/Akt/mTOR pathway and plays an important role in NSCLCs. Here we characterized mRNA and protein expression levels of mTOR and its functional associated molecules including PTEN, IGF-1R and 4EBP1 in surgically resected NSCLCs. Methods: Fifty-four patients with NSCLCs who underwent pulmonary resection were included in current study. mRNA levels of mTOR, PTEN, IGF-1R, and 4EBP1 were evaluated by RT-PCR and protein expression of mTOR, PTEN, and IGF-1R by immunohistochemistry (IHC). Association of expression of the relevant molecules with clinical characteristics, as well as correlations between mTOR and PTEN, 4EBP1 and IGF-1R were also assessed. Results: The results of RT-PCR showed that in NSCLCs, the expression level of mTOR increased, while PTEN, 4EBP1 and IGF-1R decreased. Statistical analysis indicated high IGF-1R expression was correlated with advanced clinical stage (stage III) and PTEN expression was reversely associated with tumor size (P=0.16). The results of IHC showed mTOR positive staining in 51.8% of cases, while IGF-1R positive staining was found in 83.3% and loss of PTEN in 46.3%. Protein expression of mTOR was correlated with its regulators, PTEN and IGF-1R, to some extent. Conclusions: Abnormal activation of mTOR signaling, high expression of IGF-1R, and loss of PTEN were observed in resected NSCLC specimens. The poor expression agreement of mTOR with its regulators, PTEN, and IGF-1R, implied that combination strategy of mTOR inhibitors with other targets hold significant potential for NSCLC treatment.