• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.46-54
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• 1984

A silicon-gate n-well CMOS process with 3 $\mu$m gate length was developed and its possibility for the applications was discussed,. Threshold voltage was easily controlled by ion implantation and 3-$\mu$m gate length with 650 $\AA$ oxide shows ignorable short channel effect. Large value of Al-n+ contact resistance is one of the problems in fabrications of VLSI circuits. Transfer characteristics of CMOS inverter is fairly good and the propagation delay time per stage in ring oscillator with layout of (W/L) PMOS /(W/L) NMOS =(10/5)/(5/5) is about 3.4 nsec. catch-up occurs on substrate current of 3-5 mA in this process and critically dependent on the well doping density and nt-source to n-well space. Therefore, research, more on latch-up characteristics as a function of n-well profile and design rule, especially n+-source to n-well space, is required.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.127-136
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• 2013

The islanding detection and prevention function in the important performance of the grid-connected inverter is the essential details which should be considered for worker's safety to maintain the system. This paper tries to suggest the active frequency shake islanding detection technique in the grid-connected PV generation system using sunlight. The existing active frequency drift method algorithm is described to suggest active frequency shake method algorithm. And, the algorithm which can reduce the non-detection zone, improve THD, and improve the detection speed in comparison with the existing algorithm is suggested. And we applied the proposed algorithm to the 3kW grid-connected photovoltaic inverter generation and verified the feasibility of the technique through the simulation and experiments.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.3
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• pp.433-441
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• 2022

In general, in an emergency generator system for an electric facility including an induction motor load, an emergency power generation facility larger than the facility load capacity is built due to the initial starting current of the induction motor. In order to reduce this economic burden, various methods to reduce the inrush current of induction motors are applied to suppress the additional expansion of generators due to the reduction of power generation facilities and the increase in electrical facilities. Among these methods, when a system with a built-in soft start function of an induction motor using an inverter is built, it is the best way to reduce the inrush current of the induction motor to less than the rated current. However, in this case, the installation cost of the inverter to drive the induction motor increases. This paper proposes a soft start method of an induction motor by expanding the frequency and voltage control operation area of an emergency generator. In addition, proposed a speed calculation method based on power factor information, which is essential information for stable soft start of an induction motor, and a method for generating a speed command value of the governor for starting with maximum torque.

• Journal of Power Electronics
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• v.5 no.1
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• pp.55-61
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• 2005

A fuel cell (FC) system includes a fuel processor plus subsystems to manage air, water, and thermal energy, and electric power. The overall system is high-priced and needs peripheral devices. In this paper, a FC simulator is designed and constructed with the electrical characteristics of a fuel cell generation (FCG) system, using uses a simple buck converter to overcome these disadvantages. The characteristic voltage and current (V-I) curve for the FC simulator is controlled by a simplified linear function. In addition, to verify FCG system performance and operation, a full-bridge DC/DC converter and a single-phase DC/AC inverter were designed and constructed for FC applications. Close agreement between the simulation and experimental results confirms the validity and usefulness of the proposed FC simulator.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1364-1366
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• 2002

The Photovoltaic(PV) generation system is a promising source of energy for the future. Since the need for renewable energy has been increased, the research of PV generation system has also been progressed. Recently, cost down of PV generation system has been accomplished and practical technologies of the solar energy developed, Moreover, grid connected PV generation system are becoming actual and general. Operational technology of the grid connected PV generation system is being a hot issue. Power output of PV system is directly affected by wether conditions. When AC power supply is needed, power conversion by an inverter and a MPPT control are necessary. In this paper, for stability improvement of PV generation system. Active filter(AF) function is added to PV generation system, and simulations of PV-AF system under various weather conditions are performed.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.351-352
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• 2016

Since anti-islanding scheme of grid-connected inverter is a key function of standards compliance, unintentional islanding results in safety hazards, reliability, and many other issues. Therefore, many anti-islanding schemes have been researched, however, existing anti-islanding schemes show poor power quality and non-detection zone issues. Besides, most of them have problems which deteriorate performance of islanding detection under parallel-operation. Therefore, this paper proposes a new anti-islanding scheme that has both negligible power quality degradation, no non-detection zone and precise islanding detection under parallel-operation. Finally, both simulation and experimental results validate the proposed scheme.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.103-108
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• 1996

In this paper, a novel utility connected photovoltaic power generation system with unity power factor and uninterruptable power system facility and its control strategy are proposed. The proposed photovoltaic(PV) system is connected in parallel between utility and load. The PV system provides an uninterruptable voltage to load, a maximum power tracking to solar array, and power factor correction to the utility. The proposed system has the following advantages compared with the conventional utility connected PV system. 1. Harmonic elimination Function 2. Feeding the photovoltaic energy to the utility 3. Providing the uninterruptible power source along battery to the load In case that the photovoltaic array system is on the poor power generation, the battery and capacitor of the PV system are charged by three phase utility source and the inverter in the PV system only provides the reactive current to eliminate the harmonic current exited on the utility. In the normal operation mode, the PV system supplies active power to load and reactive power to utility in order to maintain the unity power factor and to regulate ac load voltage.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.623-630
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• 2001

The conventional control techniques based a mathematical model are not well suited for dealing with ill-defined and uncertain system like a linear quadratic control. Recently, fuzzy control has been successfully applied to a wide variety of practical problems such as robot, water purification, automatic train operation system etc. In this paper, a design technique of robust Fuzzy-LQ controller for each subsystem is designed. Secondly , all the subsystem controllers are combined by fuzzy weighted averaging method. Finally the effectiveness of the proposed controller is verified through a series of computer simulations for an inverted pole system.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.637-640
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• 1991

In this paper deals with linearized control of induction motor by vector control. Output equation induced from d-q axies voltage and current equation of induction moter. The condition of induced equation is that rotor's current of axies has 0 and state current of D axies which was driven by synchronous speed is constant. The fully digital controlled induction motor drive system based on the proposed linearized method and the control circuit of system consists of 16bits micro computer and all the function are implemented with software. When the voltage source inverter control with PI controller is empolyed, in spite of secondary resistance Rr Variation, the Vector control condition is satisfied.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.406-408
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• 2005

In this literature, when the utility line is normal, the Off-Line UPS operates as an active power filter to compensate the reactive power from a load, and when the utility line is in outage, the On-Line UPS opuates as in single phase inverter to supply an active and reactive power to the load. An additional static switch in UPS was used to decrease an transient state during these mode changes. And the result shows that the transient state disappeared.