• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.73-74
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• 2007

In this paper, we design hybrid limitter balanced(HLB) power amplifier with W-CDMA signal input. Balanced power amplifier is important component that decide efficiency in communication system. General balanced power amplifier has low efficiency and high distortion characteristics. Therefore, we embodied two path with limitter that amplitude path had high efficiency amplifier using limitter and phase path had high linear amplifier to improve such problem.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.133-142
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• 2018

Paper presents a comparative study of space vector pulse width modulation (SVPWM) switching sequences for Voltage Source Inverters (VSIs). Various SVPWM switching sequences are studied for two and three level VSIs in linear modulation index region. The computations of dwell times are presented for two and three level VSIs based on space vector geometry in a synchronized and optimized manner. The existing SVPWM switching sequences are implemented using Matlab / Simulink and in an experimental setup for three phase two and three level VSIs. The simulation and experimental waveforms of conventional SVPWM (CSVPWM) and bus clamped SVPWM (BCSVPWM) are demonstrated for two and three level inverter respectively. The performance of different SVPWM switching sequences are evaluated and presented based on weighted voltage total harmonic distortion (THD).

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.270-279
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• 2018

This paper elucidates a hysteresis current controller for enhancing the performance of static synchronous compensator (STATCOM) using cascaded H-bridge multilevel inverter. Due to the rising power demand and growing conventional generation costs a new alternative in renewable energy source is gaining popularity and recognition. A five level single phase cascaded multilevel inverter with two separated dc sources, which is energized by photovoltaic - wind hybrid energy source. The voltages across the each dc source is balanced and standardized by the proposed hysteresis current controller. The performance of STATCOM is analyzed by connecting with grid connected system, under the steady state & dynamic state. To reduce the Total Harmonic Distortion (THD) and to improve the output voltage, closed loop hysteresis current control is achieved using PLL and PI controller. The performance of the proposed system is scrutinized through various simulation results using matlab/simulink and hardware results are also verified with simulation results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.69-77
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• 1998

The uninterruptible power supply (UPS) has become an integral part of modern computer and communication system to assure a continued and stable operation by providing an uninterruptible power to vital equipments. Various control methods have come to the fore in recent times with the advent of high frequency switching technologies. This paper describes the DSP control method for three phase UPS inverter which guarantees the sinusoidal output voltage under nonlinear load conditions. The proposed control scheme is verified by simulation and experiment.riment.

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.43-47
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• 2012

The unbalance currents flow the High Temperature Superconducting (HTS) power cable caused by asymmetrical fault, harmonic distortion and unbalanced load. That problem causes additional loss and leakage field in the HTS power cable, and deteriorates the electric power quality and stability. In addition, large amounts of unbalanced current can cause negative sequence and ground relays to operate. This paper presents an analysis unbalanced three-phase current distribution in HTS power cable caused by unbalanced load condition and grounding methods using PSCAD/EMTDC. The results obtained through the analysis would provide important data for the design of HTS power cables and valid information for their installation in power system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.5
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• pp.71-78
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• 2012

This paper presents a digital control solution to process capacitor current feedback of high performance single-phase UPS for non-linear loads. In all UPS the goal is to maintain the desired output voltage waveform and RMS value over all unknown load conditions and transient response. The proposed UPS uses instantaneous load voltage and filter capacitor current feedback, which is based on the double regulation loop such as the outer voltage control loop and inner current control loop. The proposed DSP-based digital-controlled PWM inverter system has fast dynamic response and low total harmonic distortion (THD) for nonlinear load. The control system was implemented on a 32bit Floating-point DSP controller TMS320C32 and tested on a 5[KVA] IGBT based inverter switching at 11[Khz]. The validity of the proposed scheme is investigated through simulation and experimental results.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.779-781
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• 1987

In phase controlled rectifier(PCR), harmonica are changed according to the variation of a firing angle. These harmonics are supplied with the input of the inverter. And then, inverter output comes about the harmonics combined with the switching frequency of the inverter. Hence the efficiency of the induction motor ia decreased by the harmonic of the inverter output. In this paper, it analyzed about an effect of these harmonics ia analyzed by a computer simulation. The total harmonic distortion (THD) in the case of PCR containing the ripple was considerably larger than THO of the DC source. Therefore, it was proved that the firing angle variation of PCR had to be limited.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.2
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• pp.34-39
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• 2001

This paper described the forces analysis of a hybrid linear pulse motor (HLPM) with high accuracy and repeatability. The HLPM is fed from a phase current by microstepping drive. The finite element method (FEM) is employed for calculating the force. The forces between mover(forcer) and stator(platen) have been calculated using the virtual work method. The detent force, rate of tooth width to tooth pitch and magnetic saturation were analyzed to considered the distortion characteristics of static thrust. The thrust to displacement produced a high pulsating force while the normal force is much higher than the thrust force.

• Journal of Power Electronics
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• v.15 no.1
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• pp.227-234
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• 2015

This paper presents the application of bee colony optimization (BCO) to obtain the optimal switching angles for single phase PWM AC choppers. The optimal switching angles are found in the region of 0-${\pi}$ based on the asymmetrical PWM technique. This PWM process results in improvements of the total harmonic distortion of the output voltage and in the input power factor. Simulation and experimental results are compared with the conventional PWM to verify the performance of the proposed PWM process.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1211-1213
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• 2003

A pulse width modulation(PWM) method for single-phase Sepic-type rectifier is introduced in this paper. The characteristics of the proposed PWM system are high performance high power factor with low input current harmonic distortion. The proposed control method is based on the average-current-mode using the dedicated integrated circuit UC3854 this technique it is possible to implement a very simple control circuit for unitary power-factor in CCM operation and also to provide over-current protection.