• 한국산학기술학회논문지
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• 제14권5호
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• pp.2106-2112
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• 2013

기존의 유압식 엘리베이터에서, 엘리베이터 카는 하강 제어 밸브에 의해 하강하며, 작동유의 유압 에너지는 하강행정 동안 손실 될 수밖에 없다. 본 연구에서는 하강행정 동안 손실되는 유압 에너지를 회수하기 위해서 유압식 엘리베이터용 하이브리드 형 에너지 저감 장치에 대해서 연구하였다. 회수된 에너지는 전기 에너지로 변환하여 저장하고, 저장된 에너지는 엘리베이터의 상승행정 동안에 보조 동력으로 사용하거나 다른 부품의 주동력으로 사용할 수 있다. 본 연구의 결과들은 에너지 저감 장치의 출력 특성이 안정적이고 양호하다는 것을 보여주고 있으며, 본 연구를 통하여 유압식 엘리베이터의 하강행정 동안 손실되는 에너지를 회수하는데 성공하였으며, 회수된 에너지를 재사용하는데 매우 유용하다는 것을 확인하였다.

• 전력전자학회논문지
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• 제21권3호
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• pp.231-237
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• 2016

Recently, the interest in DC systems to achieve more efficient connection with renewable energy sources, energy storage systems, and DC loads has been growing extensively. DC systems are more advantageous than AC systems because of their low conversion losses. However, the DC-link voltage is variable during operation because of different random effects. This study focuses on DC voltage stabilization applied in stand-alone DC microgrids by means of voltage ranges, power management, and coordination scheme. The quality and stability of the entire system are improved by keeping the voltage within acceptable limits. In terms of optimized control, the maximum power should be tracked from renewable resources during different operating modes of the system. The ESS and VSDG cover the power shortage after all available renewable energy is consumed. Keeping the state of charge of the ESS within the allowed bands is the key role of the control system. Load shedding or power generation curtailment should automatically occur if the maximum tolerable voltage variation is exceeded. PSIM-based simulation results are presented to evaluate the performance of the proposed control measures.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.1010-1014
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• 2002

A new type actuator has been designed and investigated to overcome thermal problems in slim optical disc drive which is adopted in mobile storage devices. Recently, in optical storage device technical trends, the size of optical disc drives is slimmer to adopt notebook computer and the spindle rotate velocity is faster to achieve high transfer rate and the power of actuator is higher to perform tilting, etc. However, these trends of optical disc drives tend to raise the environment temperature of drives, actuator power and parts temperature. Moreover, it is more difficult to remove the heat inside a drive and the temperature of an actuator increases and drive slims. As a result, increase of surface temperature of actuator body caused that second resonance of an actuator moves down to a lower frequency band and the performance of optical parts also deteriorates. Especially objective lens, coil and magnet of the actuator parts are easily damaged. To manage these thermal problems, in this paper an actuator with a hybrid blade, which is composed of vectra which has low thermal conductivity and magnesium which has high thermal conductivity, has been suggested and verified. Despite the high temperature environment, the proposed actuator showed good dynamic performance.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.163-169
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• 2003

Modeling of engine-generator system and its control responses are investigated using high performance generator controller. The nonlinear engine is modeled using mean torque production model based on experimental engine map. In case of diesel engine. the amount of injected fief is decided by engine controller depending on the APS(Acceleration Position Sensor) value. An electromechanical generator model contains electrical circuits and moment of inertia. The generator controller maximizes the performance of generator using decoupling and linearized current feedback control. The generator control system consists of 3-phase IGBT inverter and controller board based on 32 bit floating point DSP. Field oriented control algorithm with digital current feedback control at 10kHz sampling enabled high performance torque and speed control of induction machine. Not only the steady state but also the transient state responses can be evaluated through a batch test of the engine generator system. Developed engine and generator modeling and control can be utilized in various applications such as Series Hybrid Electric Vehicle(SHEV), engine-generator for emergency, and other hybrid generation systems.

• 한국자동차공학회논문집
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• 제13권6호
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• pp.38-47
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• 2005

In this paper, a regenerative braking algorithm is proposed to make the maximum use of the regenerative braking energy for an independent front and rear motor drive parallel HEV. In the regenerative braking algorithm, the regenerative torque is determined by considering the motor capacity, motor efficiency, battery SOC, gear ratio, clutch state, engine speed and vehicle velocity. To implement the regenerative braking algorithm, HEV powertrain models including the internal combustion engine, electric motor, battery, manual transmission and the regenerative braking system are developed using MATLAB, and the regenerative braking performance is investigated by the simulator. Simulation results show that the proposed regenerative braking algorithm contributes to increasing the battery SOC, which recuperates 60 percent of the total braking energy while satisfying the design specification of the control logic. In addition, a control algorithm which limits the regenerative braking is suggested by considering the battery power capacity and dynamic response characteristics of the hydraulic control module.

• 한국산학기술학회논문지
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• 제13권12호
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• pp.6006-6012
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• 2012

태양광 가로등 시스템에 사용되는 전원 장치는 배터리 충전을 위한 충전기와 LED Lamp를 구동하기 위한 LED 드라이버로 구성되어 있는데 일반적인 시스템에서는 별도의 전원장치로 구성되어 있다. 본 연구에서는 충전기와 LED 드라이버를 한 개의 전원장치로 구성하였다. 특히 장치의 효율을 높이기 위하여 계통 연계형 태양광 발전시스템에 적용하는 최대전력추적(Maximum Power Point Tracking: MPPT) 방식을 충전기에 적용하였다. LED 드라이버에 필수적인 정전류 방식은 충전기의 전류제어 루틴을 사용하여 구현하였다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2004년도 추계학술대회 학술발표 논문집 제14권 제2호
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• pp.211-216
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• 2004

In this thesis, we present the Takagi-Sugeno-Kang (TSK) fuzzy model based adaptive controller and adaptive identification for a general class of uncertain nonlinear dynamic systems. We use an estimated model for the unknown plant model and use this model for designing the controller. The hybrid adaptive control combined direct and indirect adaptive control based on TSK fuzzy model is constructed. The direct adaptive law can be showed by ignoring the identification errors and fails to achieve parameter convergence. Thus, we propose an TSK fuzzy model based hybrid adaptive (HA) law combined of the tracking error and the model ins error to adjust the parameters. Using a Lyapunov synthesis approach, the proposed hybrid adaptive control is proved. The hybrid adaptive law (HA) is better than the direct adaptive (DA) method without identifying the model ins error in terms of faster and improved tracking and parameter convergence. In order to show the applicability of the proposed method, it is applied to the inverted pendulum system and the performance is verified by some simulation results.

• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1293-1302
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• 1999

In this paper, an on-line process scheme is presented for implementation of a intelligent on-line modeling of nonlinear complex system. The proposed on-line process scheme is composed of FNN-based model algorithm and PLC-based simulator, Here, an adaptive fuzzy-neural networks and HCM(Hard C-Means) clustering method are used as an intelligent identification algorithm for on-line modeling. The adaptive fuzzy-neural networks consists of two distinct modifiable sturctures such as the premise and the consequence part. The parameters of two structures are adapted by a combined hybrid learning algorithm of gradient decent method and least square method. Also we design an interface S/W between PLC(Proguammable Logic Controller) and main PC computer, and construct a monitoring and control simulator for real process system. Accordingly the on-line identification algorithm and interface S/W are used to obtain the on-line FNN model structure and to accomplish the on-line modeling. And using some I/O data gathered partly in the field(plant), computer simulation is carried out to evaluate the performance of FNN model structure generated by the on-line identification algorithm. This simulation results show that the proposed technique can produce the optimal fuzzy model with higher accuracy and feasibility than other works achieved previously.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.501-503
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• 1999

In this paper, the design method of a hybrid fuzzy controller with an optimal auto-tuning method is proposed. The conventional PID controller becomes so sensitive to the control environments and the change of parameters that the efficiency of its utility for the complex and nonlinear plant has been questioned in transient state. In this paper, first, a hybrid fuzzy logic controller(HFLC) is proposed. The control input of the system in the HFLC is a convex combination by a fuzzy variable of the FLC's output in transient state and the PID's output in steady state. Second, a powerful auto-tuning algorithm is presented to automatically improve the Performance of controller, utilizing the improved complex method and the genetic algorithm. The algorithm estimates automatically the optimal values of scaling factors and PID coefficients. Controllers are applied to the plants with time-delay and the DC servo motor Computer simulations are conducted at the step input and the system performances are evaluated in the ITAE.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.444-449
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• 2009

An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds (wide frequency range) and presented in time domain.