• Journal of Electrical Engineering and Technology
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• v.4 no.2
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• pp.201-210
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• 2009

A loss minimizing controller is developed for a fuel cell electric vehicle (FCEV) permanent magnet synchronous motor (PMSM). The PMSM losses are modeled by some experimental equations. Applying Lagrangian to the loss function, a necessary condition for the optimality appears to be a fourth order polynomial, and the loss minimizing solutions are obtained by a simple numerical approach. On the other hand, the loss minimizing solutions are found by scanning the motor loss in the entire operating region. The two results agree well. The loss minimizing current sets for given torque and speed are made into a table, which is utilized as a look-up in the current control loop.

• Journal of the Korean Institute of Navigation
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• v.19 no.3
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• pp.11-19
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• 1995

When an automatic course keeping is introduced, as is quite popular in modern navigation, the closed-loop control system consists of autopilot device, power unit, steering gear, ship dynamics, and magnetic or gyrocompass. We derive mathematical models of each element of the automatic steering system. We provide a method of theoretical analysis on the propulsive energy loss related to automatic steering of ships in the open seas, taking account of the on-off(non-linear) characteristics of power unit. Also we paid attention to non-linear element installed in autopilot device, which is normally called weather adjuster. Next we make numerical calculation of the effects of autopilot control constants on the propulsive energy loss for two kinds of ship, a fishing boat and an ore carrier. Realistic sea and wind disturbances are employed in the calculation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.462-465
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• 1995

In this research a 2-dimensional motion producer based on two linear motors was developed. When the tester provides some motion through the level attached to the upper moving part of the motion producer, it provides the arbitrary intertia, damping and stiffness characteristics without actual change in physical structure of the motion producer. That is, the active impedance is implemented by controlling input currents supplied to the linear motors. A PID controller with feedforward loop was used to control the currents and pre-processing of input velocity and accleration singals from the encoder and the current singnal from the motor driver circuit are conducted to improve the performance.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.360-362
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• 2006

This paper proposes a new track-following control method using disturbance observer with the freedom of gain and frequency adaptation in optical disk drive system. Recent ODDs use smaller track pits, higher rotation speed and broader rotational speed variations to increase the data capacity and data transfer rate. This cause the degradation of track-following performance by increasing the disturbance of the rotary system. In this paper, we discussed on a DOB structure that efficiently attenuate the disturbance without effecting the overall feedback loop characteristics on CLV type ODD which uses a higher and broader range of rotational speed. DOB structure uses two band pass filter. We analyzed the track-following performance sensitivity on rotational frequency variance and gain changes. This analysis is done on a computer simulation environment and actual ODD product.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.6
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• pp.465-470
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• 2001

This paper considers a new weighed model reduction method using block diagonal solutions of Lyapunov inequalities. With the input and/or output weighting function, the stability of the reduced order system is guaranteed and an a priori error bound is proposed. to achieve this after finding the solutions of two Lyapunov inequalities and balancing the full order system, we find the reduced order systems using the direct truncation and the singular perturbation approximation. The proposed method is compared with other existing methods using numerical examples.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.3
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• pp.254-261
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• 2005

Time-optimal performances are analyzed in the sense of inner loop. A varying-time sharing thrusting logic is suggested as a new sequential paired thrusting logic for fast maneuvers of satellites with coupled thruster configuration. Its time-optimal maneuvering performance is compared with two conventional thrusting logics: separate thrusting logic and constant-time sharing sequential paired thrusting logic. It is found that the newly suggested varying-time sharing thrusting logic can be easily implemented by adjusting the conventional constant-time logic with its thrust on-time, while it can reduce the maneuvering time enormously as much as the separate thrusting logic. The performance of the logic is simulated on the agile maneuvering spacecraft model KOMPSAT-II.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.12
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• pp.1644-1651
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• 1995

A data and clock recovery integrated circuit for MAC (Multiplexed Analog Component) TV standard is described. The chip performs the recovery of a system clock from a digitally encoded voice signal, clamping of a video signal for DC-level restoration, and precise gain control of a video signal in the presence of a large amplitude variation. A PLL (Phase Locked Loop) is used for timing recovery and a new gain control circuit is proposed which enhances its accuracy and dynamic range by employing two identical four-quadrant analog multipliers. The chip is designed in full custom with 1.5um BiCMOS technology, and layout verification is completed by post-simulation with the extracted circuit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.251-257
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• 2004

AIS(Automatic Identification System), was suggested for the navigational data communication between ships and between ships and shore stations for the better safety of navigation, and it requires two different the transmitting output power level depending on its operating mode. According to ITU's recommendation, these levels should reach within 20 % of its final value in 1 ms. In this paper, an adequate feedback control circuit for power amplifier module is designed and implemented.

• Journal of Mechanical Science and Technology
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• v.20 no.8
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• pp.1195-1208
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• 2006

This paper aims at presenting robustness analysis under the uncertainties of the time delay and plant parameters in symmetrically coupled dynamic systems connected through network having time delay. The delay-involved closed loop characteristic function is mathematically formulated, incorporated with active synchronization control. And the robust stability of the corresponding system is analyzed by investigating the formation of characteristic equation containing second- order terms of uncertainty variables representing delay and plant dynamics mismatches. For the two individual types of uncertainties, we elucidate details of how to compute the bounds and what they imply physically. To support the validity of the mathematical claims, numerical examples and simulations are presented.

• Journal of Drive and Control
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• v.9 no.1
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• pp.10-17
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• 2012

Nowadays, the demand of energy saving is increasing more and more while the natural resources have been exhausted. Besides, the emission gas caused by vehicles has been being a serious environment problem. Therefore, many studies have been carried out, especially focusing on braking energy regeneration, in order to save energy as well as reduce emission of mobile vehicles. In this paper, we propose a closed-loop hydrostatic transmission for braking energy regeneration with two configurations to reduce the energy consumption by recovering the braking energy. The effectiveness of the proposed system was verified by simulation. The simulation results indicated that the pressure coupling configuration gave better performance in comparison to flow coupling configuration about 40.8%, 61.7% and 53.8% reduction of fuel consumption in 10 mode, 10 mode modified profile and highway schedules, respectively.