• Journal of Power Electronics
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• v.9 no.3
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• pp.365-376
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• 2009

In this paper, the implementation of a three-phase shunt active power filter is presented. The filter is essentially three independent single-phase current-controlled voltage source inverters (CC-VSI) with a common DC bus. The CC- VSI is operated to directly control the AC grid current to be sinusoidal and in phase with the grid voltage without detecting the load currents. The APF consists of a current control loop, which shapes the grid currents to be sinusoidal and a voltage control loop, which regulates the active power balance of the system. The experimental results indicate that the active filter is able to handle predominantly the harmonics, as well as the unbalance and reactive power, so that the grid currents are sinusoidal, in phase with the grid voltages and symmetrical.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2798-2800
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• 1999

A new circuit, modified valley fill (MVF) combined with resonant inductor of the self-excited resonant inverter and charge pump capacitors(CPCs), is presented to achieve high PF electronic ballast providing sufficient preheat current to lamp filaments for soft start maintaining low DC bus voltage. The MVF can adjust the valley voltage higher than half the peak line voltage. The CPCs draw the current from the input line to make up the current waveform during the valley interval. The measured PF and THD are 0.99 and 12%, respectively. The lamp current CF is also acceptable in the proposed circuit. The proposed circuit is suitable for implementing cost-effective electronic ballast.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.7
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• pp.323-331
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• 2000

Recently Advanced Static Var Compensators(ASVC) or STATic Synchronous COMpesator(STATCOM) has been considered as a next generation reactive power controller. The STATCOM is a voltage source inverter(VSI) based on the static VAr compensator with only small capacitors on the dc side. The main function of the STATCOM is to keep the bus voltage magnitude at the desired value. This paper compared the PAM STATCOM with the PWM STATCOM. The characteristics and the control method of each model is analyzed. And the simulation of STATCOMs based on the above two methods is presented.

• Journal of Power Electronics
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• v.12 no.5
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• pp.708-714
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• 2012

This paper presents a new interleaved pulse-width modulation (PWM) boost-flyback converter to achieve power factor correction (PFC) and regulate DC bus voltage. The adopted boost-flyback converter has a high voltage conversion ratio to overcome the limit of conventional boost or buck-boost converter with narrow turn-off period. The proposed converter has wide turn-off period compared with a conventional boost converter. Thus, the higher output voltage can be achieved in the proposed converter. The interleaved PWM can further reduce the input and output ripple currents such that the sizes of inductor and capacitor are reduced. Since boundary conduction mode (BCM) is adopted to achieve power factor correction, power switches are turned on at zero current switching (ZCS) and switching losses are reduced. The circuit configuration, principle operation, system analysis, and design consideration of the proposed converter are presented in detail. Finally, experiments conducted on a laboratory prototype rated at 500W were presented to verify the effectiveness of the converter.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.31-35
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• 2003

This paper presents a microprocessor controlled digital ballast for HID lamps, which gives intelligent features such as a precise power control, optimum ignition voltage and detection of end of life. Average current mode PFC is employed for reducing EMI and a universal input. Direct spread spectrum is done by applying 1 KHz triangular wave for removing acoustic resonance. This frequency modulation of 1 KHz gives also low EMI level and no ripple on lamp current. The microprocessor controls the voltage of DC-bus, the voltage of ignition pulses, the power of output and the bandwidth of spread spectrum. A 250W digital ballast is implemented with an efficiency of 93％ and a maximum EMI level of 55 ㏈${\mu}$V.

• Journal of Power Electronics
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• v.8 no.2
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• pp.131-140
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• 2008

This paper presents a new control approach of DSTATCOM (distribution static compensator) for compensation of reactive power, unbalanced loading and harmonic currents under unbalanced non-sinusoidal ac mains. The control of DSTATCOM is achieved using Adaline based current estimator based on LMS algorithm to maintain source currents real and undistorted. The dc bus voltage of voltage source converter (VSC) working as DSTATCOM is maintained at constant voltage using a proportional-integral (PI) controller. The DSTATCOM system alongwith proposed control scheme is modeled in MATLAB to simulate the behavior of the system. The practical implementation of the DSTATCOM is carried out using dSPACE DS1104 R&D controller having TMS320F240 as a slave DSP. Simulated and implementation results are presented to demonstrate the effectiveness of the DSTATCOM with Adaline based control to meet the severe load perturbations with different types of loads (linear and non-linear) under distorted and unbalanced AC mains.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.830-832
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• 1993

In this paper, A voltage source PWM converter which achieves bidirectional power flow between a $3{\phi}$ AC supply and a DC bus voltage is described. And the paper considers both the steady state and transient response of such a device, and develops mathematical models to describe its performance under the digital control system. As a result the AC line current becomes sinusoidal and the input power factor is improved to unity.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.916-922
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• 2014

Diode rectifiers have been widely used for an AC to DC converter. But a big problem is that they include large harmonics components in the input currents. A 12-pulse configuration with phase shifting transformer is useful for reducing them. however, it still includes the ($12{\pm}1$)th (m; integer) harmonics in the input currents. In this paper, we propose a single-phase square wave auxiliary voltage supply which is inserted in the middle DC bus. It reduces harmonics especially the 11th and 13th and the harmonic characteristic becomes almost equivalent to a 24-pulse rectifier. Theoretical analysis of the combined 12-pulse diode rectifier with the auxiliary supply is presented and a control method of the auxiliary supply is proposed. The reduction in the input current harmonics is verified by simulation using software PSIM.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.259-261
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• 2008

The electronic products such as laptop PC, cellular phone, robots and etc. need the DC power source. Recently, the secondary battery is frequently used as the portable DC power source and it needs forming process. In this paper, we proposed the bidirectional converter that the battery can be charged with high power factor and the discharged energy is regenerated into AC power source. In the charging mode, the converter acts as the boost rectifier. And the AC input current is controlled in phase with the AC input voltage. As a result, the power factor is improved nearly to unity. In the discharging mode, the DC power of battery wasted in resistor is regenerated to the AC bus line. Finally, the validity of the proposed bidirectional converter is verified by computer simulations and experimentation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2979-2984
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• 2013

This paper proposes a modeling and controller design method of Flywheel Energy Storage System(FESS) for solving the unstable operation problem in hybrid generation system with wind turbine and diesel generator applied in island area. FESS is considered as a permanent magnetic synchronous machine connected to flywheel because of its efficiency. The controller of FESS is composed of AC/DC/AC back-to-back converter. The AC/DC converter is designed to charge/discharge according to the frequency variation and the DC/AC converter to operate to keep the DC bus voltage constant. The proposed modeling and controller design method of FESS was applied to hybrid generation system with wind turbine and diesel generator. The unstable operation problem owing to wind variations was solved through simulation results.