• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.18-26
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• 2001

In this paper, we propose an ATC(Automatic Transfer mode Controller) algorithm and an average-mode-change method for use in Gear shift PLL which can automatically change loop gain. The proposed ATC algorithm accurately detects proper timing or the mode change and has a very simpler structure - than the conventional lock detector algorithm often used in QPSK. And the proposed average mode change method can obtain low errors of estimated frequency offset by averaging the loop filter output of frequency component in shift register. These algorithms are also useful in designing ASIC, since these algorithms occupy small circuit area and are adaptable for high speed digital processing. We also present phase tracking performance of proposed Gear-shift PLL, which is composed of polarity decision PD, ATC and average mode change circuit, and analyze the results by examining constellation at each mode.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1535-1544
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• 2017

Advances in FPGA technology have enabled fast real-time simulation of power converters, filters and loads. FPGA based HIL (Hardware-In-the-Loop) simulators have revolutionized control hardware and software development for power electronics. Common time step sizes in the order of 100ns are sufficient for simulating switching frequency current and voltage ripples. In order to keep the time step as small as possible, ideal switching function models are often used to simulate the phase legs. This often produces inferior results when simulating the discontinuous conduction mode (DCM) and disabled operational states. Therefore, the corresponding measurement and protection units cannot be tested properly. This paper describes a new solution for this problem utilizing a discrete-time PI controller. The PI controller simulates the proper DC and low frequency AC components of the phase leg voltage during disabled operation. It also retains the advantage of fast real-time execution of switch-based models when an accurate simulation of high frequency junction capacitor oscillations is not necessary.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.95-97
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• 2018

The power quality of Single Phase Grid-Connected Inverters (GCIs) has received much attention with the increasing number of Distributed Generation (DG) systems. However, the performance of single phase GCIs get degraded due to several factors such as the grid voltage harmonics, the dead time effect, and the turn ON/OFF of the switches, which causes the harmonics at the output of GCIs. Therefore, it is not easy to satisfy the harmonic standards such as IEEE 519 and P1547 without the help of harmonic compensator. To meet the harmonic standards a certain kind of harmonic controller needs to be added to the current control loop to effectively mitigate the low order harmonics. In this paper, the harmonic compensation is performed using a novel robust harmonic compensation method based on Digital Lock-in Amplifier (DLA). In the proposed technique, DLAs are used to extract the amplitude and phase information of the harmonics from the output current and compensate it by using a simple PI controller in the feedforward manner. In order to show the superior performance of the proposed harmonic compensation technique, it is compared with those of conventional harmonic compensation methods in terms of the effectiveness of harmonic elimination, complexity, and implementation. The validity of the proposed harmonic compensation techniques for the single phase GCIs is verified through the experimental results with a 5kW single phase GCI. Index Terms -Single Phase Grid Connected Inverter (SPGCI), Harmonic Compensation Method, Total Harmonic Distortion (THD) and Harmonic Standard.

• Journal of Power Electronics
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• v.11 no.4
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• pp.408-417
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• 2011

The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. The PHEV battery would be recharged from the power grid at home or at work and would thus allow for a reduction in the overall fuel consumption. This paper proposes an integrated power electronics interface for PHEVs, which consists of a novel Eight-Switch Inverter (ESI) and an interleaved DC/DC converter, in order to reduce the cost, the mass and the size of the power electronics unit (PEU) with high performance at any operating mode. In the proposed configuration, a novel Eight-Switch Inverter (ESI) is able to function as a bidirectional single-phase AC/DC battery charger/ vehicle to grid (V2G) and to transfer electrical energy between the DC-link (connected to the battery) and the electric traction system as DC/AC inverter. In addition, a bidirectional-interleaved DC/DC converter with dual-loop controller is proposed for interfacing the ESI to a low-voltage battery pack in order to minimize the ripple of the battery current and to improve the efficiency of the DC system with lower inductor size. To validate the performance of the proposed configuration, the indirect field-oriented control (IFOC) based on particle swarm optimization (PSO) is proposed to optimize the efficiency of the AC drive system in PHEVs. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point, where the PSO is applied to evaluate the optimal flux. Moreover, an improved AC/DC controller based Proportional-Resonant Control (PRC) is proposed in order to reduce the THD of the input current in charger/V2G modes. The proposed configuration is analyzed and its performance is validated using simulated results obtained in MATLAB/ SIMULINK. Furthermore, it is experimentally validated with results obtained from the prototypes that have been developed and built in the laboratory based on TMS320F2808 DSP.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1537-1541
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• 2003

In this paper, presented is a feedback control performance of vibratory gyroscope at various vacuum levels. Micro gyroscope, whose operation is based on the vibrating motion at the vacuum conditions, is highly influenced by the vacuum level of the operating circumstances. In general, we apply the feedback control scheme to the gyroscope in order to improve the performances of the sensor. And control performances of the gyroscope are related to those vacuum levels. So we need investigate the performances of the closed loop control at various vacuum conditions comparing with those of the open loop. The experimental results show that the sensitivity of the closed loop is less than that of the open loop especially in low vacuum conditions. Therefore, there should be trade-off between sensitivity and other sensor performances such as linearity, bandwidth when we apply feedback control to the gyroscope.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.45-53
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• 1998

Traction control systems(TCS) improve vehicle acceleration performance and stability, particularly on slippery roads through engine torque and/or brake torque control. This research mainly deals with the engine control algorithm based on adjustment of the engine throttle valve opening. Hardware-in-the-loop simulation(HWILS) is carried out where the actual hardware is used for the engine/automatic transmission and TCS controller, while various vehicle dynamics are simulated on real-time basis. Also, use of the dynamometer is made in order to implement the tractive force that a road applies to the tire. Although some restrictions are imposed mainly due to the capability of the synamometer, simplified HWILS results show that the slip control algorithm can improve the vehicle acceleration performance for low-friction roads.

• Journal of Power System Engineering
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• v.2 no.2
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• pp.41-46
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• 1998

This paper presents the vibration control for the two degree-of-freedom which is a reduced model of multi-layer structure. This reduced model is designed for the first and second order resonance in the low frequency domain where the disturbance such as the earth quake has the large energy. And a designed controller using the LQ type $H_{\infty}$ control theory shows the good performance for the impulse disturbance through the experimental results and the simulation results respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.218-222
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• 1993

A sliding mode controller associated with the moving sliding surface is formulate for the tip position control of a single-link flexible manipulator. After establishing the plant model which characterizes a noncollocated control system, a discontinuous control law is then constructed by restricting that velocity state variables are not available from direct sensor measurements. Using the proposed control law favorable system responses are accomplished through shortening the reaching phase without increasing maximum control torque. Furthermore, a low sensitiveness to extraneous disturbance is obtained. Computer simulations are undertaken in order to demonstrate these superior control performance characteristics to be accrued from the proposed methodology.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.2
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• pp.144-155
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• 1992

A design of a highly stable current-controlled power supply combining the phase-controlled rectifier (PCR), passive filter and active filter is investigated. A digital phase-looked voltage control (PLVC) with a capability of compensating the thyristor firing angles under unvalanced power source is proposed` otherwise the PCR output voltage has low-order subharmonics whose suppression requires a bulky passive filter. The digital PLVC has a fast dynamic characteristics as an inner control loop of the PCR. To suppress further the output ripple, an active filter using a transformer is introduced and its design is described through the frequency domain analysis. An optimal integral, proportional and measurable variable feedback (IPM) controller is designed using the time-weighted performance index based on the time domain analysis. The design method based on the time-weighted performance index gives better response characteristics than that based on the conventional performance index. It is also shown via experimental results that the proposed scheme gives better response characteristics than that based on the conventional performance index. It is also shown via experimental results that the proposed scheme gives good dynamic and static performances.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.546-551
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• 1993

A new robust sliding mode controller is formulated for the tip position control of a single-link flexible manipulator with parameter variations. After establishing the plant model characterized by a noncollocated uncertain control system, a sliding surface which guarantees stable sliding mode motion is synthesized in an optimal manner. The surface is then modified to adapt arbitrarily given initial conditions. A discontinuous control law associated with the modified surface is designed by restricting that velocity state variables are not available from direct sensor measurements. Using the proposed control law favorable system responses are accomplished through shortening the reaching phase of state trajectory without increasing maximum control torque as well as undesirable chattering. Furthermore, a low sensitiveness to uncertainties is obtained from inherent salient properties of the proposed control system. Computer simulations are undertaken in order to demonstrate these superior control performance characteristics to be accrued from the proposed methodology.