• Journal of Power Electronics
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• v.18 no.2
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• pp.533-546
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• 2018

This study proposes a comprehensive mathematical model that includes coil-system circuit and loss models for power converters in wireless power transfer (WPT) systems. The proposed model helps in understanding the performance of WPT systems in terms of coil-to-coil efficiency, overall efficiency, and output power capacity and facilitates system performance optimization. Three methods to achieve constant output power for variable-load systems are presented based on system performance analysis. An optimal method can be selected for a specific WPT system by comparing the efficiencies of the three methods calculated with the proposed model. A two-coil 1 kW WPT system is built to verify the proposed mathematical model and constant output power control methods. Experimental results show that when the load resistance varies between 5 and $25{\Omega}$, the system output power can be maintained at 1 kW with a maximum error of 6.75% and an average error of 4%. Coil-to-coil and overall efficiencies can be maintained at above 90% and 85%, respectively, with the selected optimal control method.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1109-1116
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• 2017

Wireless power transfer (WPT) technology has the advantages of intelligence and facilitation. This paper designs a WPT system applied to battery charging and provides a strategy which switches from the constant current (CC) charging mode to constant voltage (CV) charging mode. The LCL-LCL topology is used to realize the CC output, while the LCL-S (series compensation) topology is used to realize the CV output. The main factor affecting the output characteristics is extracted by analyzing the two topologies above. Based on the main factor, this paper puts forward a modified way to design the system. In addition, on-line monitors for the battery and switches are placed at receiving side, which avoids the need for introducing an information interaction module into the system. Therefore, the complexity of the controlling system is reduced. Finally, simulation and experimental analyses are carried out to verify the correctness of the compound topologies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.2028-2037
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• 2009

This paper presents the simulator for dynamic modeling of a MT(micro turbine) during start-up period. The simulator is implemented by modeling a dynamic power of main components of a MT including compressor, combustor and turbine. A modeling for a MT under steady state operation can be accurately built from thermodynamics analysis. But dynamic modeling during start-up period is very difficult because efficiency of main components is very low and the designed value has big error and nonlinear characteristics during start-up. In this paper, new method without using thermodynamics analysis during start-up is proposed for the simulator. The power models of main components are derived from analysis of the experimental operation data by test motoring using a electric starter under constant power output. The simulator is developed using MATLAB/Simulink. For constant power output control, sensorless vector inverter is designed and algorithms for starting from stall and method for controling a output power are proposed. The performance of developed simulator is verified by comparing experimental and simulation start-up results.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.2
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• pp.106-117
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• 2022

Multiple output converters can be utilized when various output voltages are required in applications. Recently, one of the multiple output converters called fly-buck has been proposed, and has attracted attention due to the advantage that multiple output can be easily obtained with a simple structure. When constant on-time (COT) control is applied, the output ripple voltage must be treated carefully for control stability and voltage regulation characteristics in consideration of the inherent energy transfer characteristics of the fly-buck converter. This study analyzes the operation principle of the fly-buck converter with a ripple generation network and presents the design guideline for the improved output voltage regulation. Validity of the analysis and design guideline is verified using a 5 W prototype of the COT controlled fly-buck converter with a ripple generation network for telecommunication auxiliary power supply.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.3
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• pp.96-100
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• 2004

The Nd： YAG laser is commonly used throughout many fields such as accurate material processing, IC marking, semiconductor annealing, medical operation devices, etc., due to the fact that it has good thermal and mechanical properties and is easy to maintain. In materials processing, it is essential to vary the laser power density for specific materials. The laser power density can be mainly controlled by the current pulse width and pulse repetition rate. It is important to control the laser energy in those fields using a pulsed laser. In this paper we propose the constant-frequency current resonant half-bridge converter and monitoring of capacitor charging voltage. This laser power supply is designed and fabricated to have less switching loss, compact size, isolation with primary and secondary transformers, and detection of capacitor charging voltage. Also, the output stabilization characteristics of this Nd： YAG laser system are investigated. The test results are described as a function of laser output energy and flashlamp arc discharging constant. At the energy storage capacitor charges constant voltage, the laser output power is 2.3％ error range in 600[V].

• Journal of Power Electronics
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• v.16 no.2
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• pp.675-684
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• 2016

This paper presents a new stand-alone wind-based induction generator system with constant frequency and adjustable output voltage. The proposed generator consists of a six-phase cage-rotor induction machine with two separate three-phase balanced stator windings and a three-phase space vector pulse width modulation inverter that operates as a static synchronous compensator (STATCOM). The first stator winding is fed by the STATCOM and used to excite the machine while the second stator winding is connected to the generator external load. The main frequency of the STATCOM is determined to be constant and equal to the load-requested frequency. The generator output frequency is independent of the load power demand and its prime mover speed because the frequency of the induced emf in the second stator winding is the same as this constant frequency. A sliding mode control (SMC) is developed to regulate the generator output voltage. A second SMC is used to force the zero active power exchanged between the machine and the STATCOM. Some simulation and experimental results are presented to prove the validity and effectiveness of the proposed generator system.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.547-553
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• 1998

In this paper, we composed of utility interactive pv generation system of voltage source inverter, and represented uninterrutible power supply (UPS) equipment maintaining constant voltage, using a pulse width modulation(PWM) voltage fed inverter, as power source disconnection, voltage variation and output current variation with load variation. This system is driven by being synchronized voltage fed inverter and AC source, and in the steady state of power source charge battery connected to dc side with solar cell using a photovoltaic (PV) that it was so called constant voltage charge. In addition, better output waveform was generated because of PWM method, and it was proved to test by experiment maintained constant output voltage regardless of AC source disconnection, load variation, and voltage variation of AC power source.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1718-1726
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• 2010

Utilization of renewable energy is becoming increaingly important from the viewpoints of environmental protection and conservation of fossil fuel. However, the generating power of renewable energy is always fluctuating due to the environmental status. This paper presents a scheme for supervisory control of wind generation system with the energy storage and STATCOM to reduce the power variation. In this paper, we especially concentrate on constant power output control of wind generation system. In order to achieve this purpose, the coordinated control strategy between different types of energy storage system and reactive power compensation device. The proposed control scheme has been validated by PSCAD/EMTDC simulation. As a result, the proposed scheme can handle the power output of wind generation system with a constant value.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.216-226
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• 2015

The neutral beam injection generate ultra-high temperature energy in the tokamak of nuclear fusion. The neutral beam injection make up arc power supply, filament power supply and acceleration & deceleration power supply. The arc power supply has characteristics of low voltage and high current. Arc power supply generate arc through constant output of voltage and current. So this paper proposed suitable buck converter for low voltage and high current. The proposed buck converter used parallel switch because it can be increased capacity and decrease conduction loss. When an arc generated, the neutral beam injection chamber occur high voltage. And it will break output capacitor of buck converter. Therefore the output capacitor was removed in the proposed converter. Thus the proposed converter should be designed for the characteristics of low voltage and high current. Also, the arc power supply should be guaranteed for system stability. The proposed parallel buck converter enables the system stability of the divided low output voltage and high current. The proposed converter with constant output be the most important design of the output inductor. In this paper, designed arc power supply verified operation of system and stability through simulation and prototype. After it is applied to the 288[kW] arc power supply for neutral beam injection.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1654-1663
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• 2015

Compared to LC resonance, LCL resonance has distinct advantages such as a large resonant capability, low voltage and current stresses of the power device, constant voltage or current output characteristics, and fault-tolerance capability. Thus, LCL resonant compensation is employed for a movable Inductive Contactless Power Transfer (ICPT) system with a multi-load in this paper, which achieves constant current output characteristics. Peculiarly, the primary side adopts a much larger compensation inductor than the primary leakage inductor to lower the reactive power, reduce the input current ripple, generate a large current in the primary side, and realize soft-switching. Furthermore, this paper proposes an approximate resonant point for large inductor-ratio LCL resonant compensation through fundamental wave analysis. In addition, the PWM control strategy is used for this system to achieve constant current output characteristics. Finally, an experimental platform is built, whose secondary E-Type coils can ride and move on a primary rail. Simulations and experiments are conducted to verify the effectiveness and accuracy of both the theory and the design method.