• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.6
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• pp.564-571
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• 2014

A single-stage current-balancing multi-channel light-emitting diode (LED) driver is proposed in this study. The conventional LED driver system consists of two cascaded power conversion stages, i.e., an isolation DC/DC converter and LED driver. LED driver is usually implemented with the same number of expensive boost converters as those of LED channels to tightly control the current through each LED channel. Therefore, its overall system size is not only bulky, but the cost is rather high. By contrast, the proposed LED driver system is composed of a single power stage with the DC/DC converter and LED driver merged. Although the current balancing circuit of the proposed LED driver requires only passive devices instead of expensive boost converters, all currents through multi-channel LEDs can be well balanced. Therefore, the proposed LED driver features a small system size, improved efficiency, and low cost. To confirm the validity of the proposed driver, its operation and performance are verified on a prototype for a 46" LED TV.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.193-195
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• 2007

These days, to change the new & renewable energy change the subject because environmental pollution and exhausted fossil power. The most notable Fuel cells by one of the new & renewable energies are one of very useful power conversion sources. Their advantages are low environmental pollution, highly efficient power generation, diversity of fuels (natural gas, LPG, methanol and naphtha), and reusability of exhaust heat, modularity, and faster installation. PEMFC by one of the Fuel Cells is the energy of new technology which is produced by the electric chemical reaction directly. The essential composition elements of PEMFC stack are membrane electrode assembly (MEA), catalyst, Bipolar Plate. Under the this study, know-how is manufacturing single cell of PEMFC and Study design of Low Voltage, Low Electric Power System by PEMFC Single Cell.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.488-491
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• 2006

In this paper proposed method of maximum power point tracking using boost converter for a connected single phase inverter with photovoltaic system. The maximum power point tracking control is based on generated circuit control MOSFET switch of boost converter and single phase inverter uses predicted current control to control four IGBT's switch in full bridge. The predicted current control provide current with sinusoidal wave shape and inphase with voltage. The generation control circuit allows each photovoltaic module to operate independently at peak capacity, simply by detecting of the output power of the system. Furthermore, the generation control circuit attenuates low-frequency ripple voltage, which is caused by the full-bridge inverter, across the photovoltaic modules. Consequently, the output power of system is increased due to the increase in average power generated by the photovoltaic modules. The effectiveness of the proposed inverter system is confirmed experimentally and by means of simulation.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.535-538
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• 1994

In this paper, an isolated ZVS-PWM boost converter is proposed for single stage line conversion. For power factor correction, we used the half bridge topology at the primary side of isolation transformer permitting switching devices to operate under ZVS by using circuit parastics and operating at a fixed duty ratio near 50%. Thus the relatively continuous input current distortion and small size input filter are also achievable. The ZVS-PWM boost operation of the proposed converter can be achieved by using the boost inductor $L_f$, main switch $Q_3$, and simple auxiliary circuit at the secondary side of isolation transformer. The secondary side circuit differ from a conventional PWM boost converter by introduction a simple auxiliary circuit. The auxiliary circuit is actived only during a short switching transition time to create the ZVS condition for the main switch as that of the ZVT-PWM boost converter. With a single stage, it is possible to achieve a sinusoidal line current at unity power factor as well as the isolated 48V DC output. Comparing to the two stage schemes, overall effiency of the proposed converter is highly improved due to the effective ZVS of all devices as well as single stage power conversion. Thus, it can be operated at high switching frequency allowing use of small size input filter. Minimum voltage and current stress make it high power application possible.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.27-35
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• 2013

SCR (Selective Catalytic Reduction) on DPF (Diesel Particulate Filter) is a multi-functional after-treatment device which integrates soot filtration and DeNOx function into a single can. Because of its advantage in package and cost, the SCR on DPF is considered as a potential candidate for future application. It inherently employes wall flow type monolithic reactor so ash included in exhaust gas may deposit inside the inlet channel of this device. This study is intended to identify the impact of ash deposit on SCR reaction under wall flow type monolithic reactor. Simulation approach is used so relevant species transport equations for wall flow type monolith is derived. These equations can be solved together with momentum conservation equations and give solution for conversion performance. Both ash deposit and clean catalyst case are simulated and comparison of these two cases gives an insight for the impact of ash deposit on conversion performance. Ash deposit can be classified as ash layer and ash plug. and impact of ash deposit is described along with different morphology of ash deposit.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.4
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• pp.193-199
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• 2001

This paper suggests a novel single-stage drive for a switched reluctance motor (SRM) to achieve sinusoidal, near unity power factor input currents. The proposed drive is very simple without additional active switch. As a single-stage approach, which combines a DC link capacitor used as dc source and a drive used for driving the motor into one power stage, a simple structure and low cost drive in implemented. A prototype drive for an 8/6 pole SRM equipping a suitable encoder is designed to evaluate the proposed topology. Also subscription control algorithm is presented. The characteristics and validity of the proposed circuit will be discussed in depth through the experimental results.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.6
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• pp.58-70
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• 1997

In this paper, an 8bit CMOS low power, high-speed current-mode folding and interpolation A/D converter is designed with te LG semicon $0.8\mu\textrm{m}$ N-well single-poly/double-metal CMOS process to be integrated into a portable image signal processing system such as a digital camcoder. For good linearity and low power consumption, folding amplifiers and for high speed performance of the A/D converter, analog circuitries including folding block, current-mode interpolation circuit and current comparator are designed as a differential-mode. The fabricated 8 bit A/D converter occupies the active chip area of TEX>$2.2mm \times 1.6mm$ and shows DNL of $\pm0.2LSB$, INL of <$\pm0.5LSB$, conversion rate of 40M samples/s, and the measured maximum power dissipation of 33.6mW at single +5V supply voltage.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.56-58
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• 2002

In this paper, the double conversion gate mixer using a half-LO frequency is described at 25 GHz band. The proposed mixer uses two HEMTs excited by a single LO signal of half-LO frequency in order to generate the second IF signal. That is, the LO signal having the half-LO frequency is only fed into the gate of the first HEMT mixer as a normal gate mixer. The LO signal through the first mixer is find into the second mixer The proposed miler requires not only half of the normal LO frequency, but also lower LO power than the conventional subharmonically pumped milers. Over the bandwidth of 500 MHz at 24.5 GHz, the conversion gain is 2.5 dB, the noise figure is 9 dB, and the isolation between RF and LO port is 32 dB when the LO poller is 0 dBm at 12.65 GHz.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.3
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• pp.18-29
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• 1993

In single mode fiber optic transmission systems(FOT's) operated at high modulation rates over long fiber spans, chromatic dispersion can produce distortion in the demodulated waveforms, resulting in intersymbol interference(ISI) in the received signal and a reduction of transmission system performance. In this paper, chromatic dispersion limitations for intensity modulation and direct detection(IM-DD) systems are studied by considering the effect of phase modulation to amplitude modulation (PM-AM) conversion noise. Laser phase noise conversion to amplitude noise due to fiber chromatic dispersion is analyzed by deriving the noise power spectral density. We first derive the noise power spectral density of the laser phase noise to intensity noise conver- sion. Next, also evaluate the system power penalty and the transmitter laser linewidth required to avoid PM-AM conversion noise penalties in long-haul nonregenerative transmission system using an external modulator and optical amplifiers. For such system with optical amplifiers, transmission sys- tem length is limited due to fiber chromatic dispersion, even if an ideal external modulator is used.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.12
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• pp.609-615
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• 2005

A 30kW electrical power conversion system is developed for a variable speed wind turbine. In the wind energy conversion system(WECS) a synchronous generator with field current excitation converts the mechanical energy into electrical energy. As the voltage and the frequency of the generator output vary according to the wind speed, a 6-bridge diode rectifier and a PWM boost chopper is utilized as an ac-dc converter maintaining the constant dc-link voltage with only single switch control. An input current control algorithm for maximum power generation during the variable speed operation is proposed without any usage of speed sensor. Grid connection type PWM inverter converts dc input power to ac output currents into the grid. The active power to the grid is controlled by q-axis current and the reactive power is controlled by d-axis current with appropriate decoupling. The phase angle of utility voltage is detected using software PLL(Phased Locked Loop) in d-q synchronous reference frame. Experimental results from the test of 30kW prototype wind turbine system show that the generator power can be controlled effectively during the variable speed operation without any speed sensor.