• 전력전자학회논문지
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• 제22권1호
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• pp.1-8
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• 2017

The optimal gain design method of a three-phase boost converter is proposed in this study. The control system has a two-loop configuration, in which each controller is coupled closely; thus, the optimal design is difficult to achieve using conventional gain-tuning method. The proposed method is adopted to the MATLAB SISO TOOL software and is based on the controller requirements, which are phase margin and cut-off frequency of the open-loop system. The optimal proportional -integral gains can be designed easily using the proposed interactive method of the SISO TOOL. The performance of the proposed system is verified through simulation and experiments.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.153-159
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• 2012

In photovoltaic system, the characteristic of photovoltaic module such as open circuit voltage and short circuit current will be changed because of cell temperature and solar radiation. Therefore, a boost converter of the PV system connects between the output of photovoltaic system and DC link capacitor of grid connected inverter as controlling duty ratio for maximum power point tracking(MPPT). This paper shows the dynamic characteristic of the boost converter by comparing single-loop control algorithm and two-loop control algorithm using both analog and digital control. The proposed both compensation method has been verified with computer simulation and simulation results obtained demonstrate the validity of the proposed control schemes.

• 전력전자학회논문지
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• 제13권6호
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• pp.403-410
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• 2008

본 논문에서는 벡터제어에 필요한 유도전동기의 상수를 정지 상태에서 부가적인 신호 주입을 이용하여 추정하는 방법을 제안하였다. 농형 유도전동기 회전자 바의 표피효과를 수학적으로 모델링을 하고 분석하였다. 상수 추정을 위해 정지 상태에서 두 가지의 서로 다른 주파수의 신호를 주입한다. 전동기의 초기 상수를 알지 못하므로 개-루프 전압 주입방법 대신 폐-루프 전류제어 방법을 이용한다. 이 방법은 전기적 사고를 미리 방지할 수 있으므로 개-루프 전압 주입방법 보다 안전하다. 그리고 유도전동기의 상수 추정에 심각한 영향을 주는 위상지연효과를 보상하기 위한 오프라인 시험방법을 제안하였다. 그리고 제안된 상수 추정 방법의 타당성을 증명하기 위해 세 가지 용량의 유도전동기에 대해 실험을 수행하였다.

• 한국태양에너지학회 논문집
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• 제32권spc3호
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• pp.245-254
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• 2012

In photovoltaic system, the characteristics of photovoltaic module such as open circuit voltage and short circuit current will be changed because of cell temperature and solar radiation. Therefore, the boost converter of a PV system connects between the output of photovoltaic system and DC link capacitor of grid connected inverter as controlling duty ratio for maximum power point tracking(MPPT). This paper shows the dynamic characteristics of the boost converter by comparing single-loop and two-loop control algorithm using both analog and digital control. Both proposed compensation methods have been verified with computer simulation to demonstrate the validity of the proposed control schemes.

• 한국정보통신학회논문지
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• 제10권1호
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• pp.15-22
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• 2006

OFDMA 시스템에서 단말기는 기지국과 같이 최소 1개부터 최대일 때 부채널 전부를 사용할 수 있지만 단말기의 송신전력은 기지국보다 낮게 설계되기 때문에 부채널 전부를 사용할 수 있는 거리(FLR : full loading range)의 제한이 생기고 FLR 외부에 위치한 단말은 기존의 개방루프 전력제어 방식을 사용할 수 없는 문제가 발생한다. 본 논문에서는 OFDMA 시 스템의 ranging 정보를 이용하여 단말기의 위치를 파악하고 단말기의 위치에 따라서 사용가능한 부채널수를 제한하고 PCG(power concentration gain)를 인가하는 방식을 제안하였다. 시뮬레이션을 통한 실험 결과에서 제안된 방식은 단말기의 위치에 따라서 상향링크 무선자원의 최적 활용을 가능하게 하며 FLR 외부에서 개방루프 전력 제어가 별도의 하드웨어 없이 가능함을 확인하였다.

• ETRI Journal
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• 제19권3호
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• pp.98-115
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• 1997

The architecture of the CDMA mobile system (CMS) is developed based on three function groups - service resource, service control, and service management groups. In this paper, the CMS architecture is discussed from the point of view of implementing these functions. The variable length packets are used for transmission. The synchronization clock signals are derived form the GPS receiver. The open loop and closed loop techniques are used for the power control. The internationally accepted signaling and network protocols are employed. The call control for the primary services in designed to provide efficient mobile telecommunication services. The softer handoff is implemented in one card. The mobile assisted handoff and the network assisted handoff are employed in the soft and hard handoffs. The authentication is based on the secret data which includes random numbers. The management functions, which include the location management, resource management, cell boundary management and OAM management, are implemented to warrant the system efficiency, maximum capacity and high reliability. The architecture ensures that the CMS is flexible and expandable to provide subscribers with economic and efficient system configuration. The dynamic power control, adaptive channel allocation. and dynamic cell boundary management are recommended for future work.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.526-527
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• 2010

본 논문에서는 슬라이딩 모드 관측기를 이용하여 IPMSM(Interior Permanent Magnet Synchronous Motor)의 센서리스 제어의 기동특성에 관한 연구를 수행하였다. IPMSM의 센서리스 제어는 초기 구동시 회전자의 위치를 알 수가 없으므로 Open-Loop알고리즘을 이용하여 강제로 모터를 구동시킨다. 그러므로 Open-Loop에서 Closed-Loop로 제어되는 시점에서 부하의 상태에 따라 기동 특성에 문제점을 야기 시킬 수 있다. 본 논문에서는 부하에 따라 기동 특성에서 야기되는 문제점과 해결책을 제시한다. 제시된 방법을 시뮬레이션을 통해 검증한다.

• 전력전자학회논문지
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• 제24권4호
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• pp.229-236
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• 2019

This study proposes a DC-DC converter topology of solid-state transformer for low-voltage DC distribution. The proposed topology consists of a voltage balancer and bipolar DC-DC converter. The voltage and current equations are obtained on the basis of switching states to design the controller. The open-loop gain of the controller is achieved using the derived voltage and current equations. The controller gain is selected through the frequency analysis of the loop gain. The inductance and capacitance are calculated considering the voltage and current ripples. The prototype is fabricated in accordance with the designed system parameters. The proposed topology and designed controller are verified through simulation and experiment.

• 제어로봇시스템학회논문지
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• 제19권4호
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• pp.299-305
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• 2013

The complexity and severe nonlinearity of multi-machine power systems make it difficult to design a control input for voltage regulation using modern control theory. This paper presents a model-based PID control scheme for the regulation of the bus voltage to a desired value. To this end, a fourth-order linear system is constructed using input and output data obtained using the TSAT (Transient Security Assessment Tool); the input is assumed to be applied to the grid through the STATCOM (STATic synchronous COMpensator) and the output from the grid is a bus voltage. On the basis of the model, it is identified as to which open-loop poles of the system make the response to a step input oscillatory. To reduce this oscillatory response effectively, a model-based PID control is designed in such a way that the oscillatory poles are no longer problematic in the closed loop. Simulation results show that the proposed PID control dampens the response effectively.

• 드라이브 ㆍ 컨트롤
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• 제16권3호
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• pp.23-32
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• 2019

This study proposed a fault tolerant control algorithm for electro-hydraulic brake systems where permanent magnet synchronous motor (PMSM) drive is adopted to boost the braking pressure. To cope with motor position sensor faults in the PMSM drive, a braking pressure controller based on an open-loop speed control method for the PMSM was proposed. The magnitude of the current vector was determined from the target braking pressure, and motor rotational speed was derived from the pressure control error to build up the braking pressure. The position offset of the pump piston resulting from a leak in the hydraulic system is also compensated for using the open-loop speed control by moving the piston backward until it is blocked at the end of stroke position. The performance and stability of the proposed controller were experimentally verified. According to the results, the control algorithm can be utilized as an effective means of degraded control for electro-hydraulic brake systems in the case that a motor position sensor fault occurs.