• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.4
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• pp.159-164
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• 2005

Various compensators are installed into the power system to operate the system economically and stably by maximizing the availability of utilities and power transmission capability. Fixed Capacitor(FC), Mechanical Switched Capacitor(MSC), and FACTS(Flexible AC Transmission Systems) are used to regulate voltage and power flow of the system. When a disturbance occurs in the power system, the Fixed Capacitor operates dependently on the voltage of the power system and cannot change the amount of installation automatically. But compared to other equipment, the Fixed Capacitor is more economical due to its low cost. Since MSC can change the amount of installation according to the state of the power system, operates more effectively than the Fixed Capacitor. FACTS have fast dynamic performance for the transient condition, but the cost is high. Therefore, it is needed to develop an optimized installation planning for the reactive power compensators by considering their dynamic performance and cost. In this paper, an optimized compensator combination and the proposed scheme is proposed and it is applied to KEPCO system in order to show its capabilities.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.3
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• pp.13-18
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• 2010

This work proposes and characterizes switched-capacitor type cyclic digital-to-analog converter for display data driving. The proposed digital-to-analog converter composes simple structure, and can be implemented for low-power, small area display driver ICs. By circuit level simulations, it is verified that the op-amp input referred offset is attenuated at the DAC output and the circuit performance is robust at 0.5% of capacitor mismatch.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.67-73
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• 1996

Subsynchronous resonance(SSR) causes a torsional shaft torque on the generator. Damages resulting from the uncontrolled SSR have resulted in the breakdown in the shaft and costs for replacement power. This paper is to determine the feasibility of controlling SSR by the fast modulation of series compensation capacitors. The presence of subsynchronous currents in the system was detected by a subsynchronous relay which was modeled by the transient analysis of control systems(TACS) in electromagnetic transients program (EMTP). The capacitor segments were switched by bi-directional thyristor switches. These were modeled into EMTP. The strategy to switch the capacitors were modeled as a closed loop system. The paper proves that effective control of SSR can be obtained only by the detuning of the system and the removal or blocking of subsynchronous energy from the system. (author). refs., figs., tabs.

• Journal of Power Electronics
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• v.7 no.2
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• pp.118-123
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• 2007

This paper presents a new ZCS-PWM high frequency inverter. Zero current switching operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. Dual duty cycle control scheme is used to provide a wide range of high frequency AC output power regulation that is important in many high frequency inverter applications. It found that a complete soft switching operation can be achieved even for low power setting ranges by introducing high-frequency dual duty cycle control scheme. The proposed high frequency inverter is more suitable for consumer induction heating(IH) applications. The operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.179-180
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• 2015

The task of measuring losses becomes more challenging with ever increasing efficiencies and operating frequencies in power electronics applications. Generally, the process of traditional switching loss calculation in flyback converter is very complicated. MOSFET drain-source voltage and current waveforms are needed to calculate switching loss. However, as we know in switched capacitor converter, switching loss can be easily calculated by charge and energy conservation law with known initial and final capacitor voltages. In this paper, the same method is applied to fly-back converter switching loss analysis to simplify calculation procedure.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1015-1019
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• 2001

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.2
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• pp.25-33
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• 2007

In this paper, a fourth-order single-bit delta-sigma modulator is presented and implemented. The loop-filter is composed of both feedback and feedforward paths. Measurement results show that maximum 99dB dynamic range is achievable at a clock rate of 3.2MHz for 20kHz baseband. The proposed modulator has been fabricated in a $0.18{\mu}m$ standard CMOS process.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.4
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• pp.286-292
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• 2006

This paper presents the design of a low-voltage wide-band switched-capacitor (SC) filter for wireless communication receiver applications. The filter is the 5th-order Elliptic lowpass filter. With the clock frequency of 50MHz implying that an effective sampling frequency is 100MHz with double sampling scheme, the cut-off frequency of the filter is programmable to be 1.25MHz, 2.5MHz, 5MHz and 10MHz. For low-power systems powered by a single-cell battery, the SC filter was elaborately designed to operate at 1.2V power supply. Simulation result shows that the 3rd-order input intercept point (IIP3) can be up to 27dBm. The filter was fabricated in a $0.25-{\mu}m$ 1P5M standard CMOS technology and measured frequency responses show good agreement with the simulation ones. The current consumption is 34mA at a 1.2V power supply.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.55-59
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• 2002

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current -fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.2
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• pp.49-55
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• 2003

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.