• Current Photovoltaic Research
• /
• v.3 no.4
• /
• pp.107-111
• /
• 2015

Current characteristic curve of an illuminated solar cell was used to determine its reverse saturation current density ($J_0$), ideality factor (n) and resistances, by using numerical diode simulation. High efficiency amorphous silicon, heterojunction crystalline Si (HIT), plastic and organic-inorganic halide perovskite solar cell shows n=3.27 for a-Si and n=2.14 for improved HIT cell as high and low n respectively, while the perovskite and plastic cells show n=2.56 and 2.57 respectively. The $J_0$ of these cells remain within $7.1{\times}10^{-7}$ and $1.79{\times}10^{-8}A/cm^2$ for poorer HIT and improved perovskite solar cell respectively.

• Proceedings of the KIPE Conference
• /
• 2001.07a
• /
• pp.569-575
• /
• 2001

The three-phase diode rectifier with capacitive Inter is highly sensitive to line voltage unbalance. Because of its inherent nonlinear characteristics small line voltage unbalance may cause highly unbalanced line current causing detrimental effects on power quality. This paper presents a theoretical basis on this 'unbalance amplification effect' and derives an analytical model of line current characteristics under unbalanced line voltage condition for various modes of operation. The results provide a basic and important guideline for optimal design of a three-phase diode rectifier with capacitive filter that is most commonly used for interfacing various power conversion equipments to power lines.

• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.806-808
• /
• 1993

New soft recovery drive which can alleviate the loss due to reverse recovery of diode is proposed. By using this drive, the reverse current of the diode is minimized and stabilized because there is inner local feedback loop between the turn-on current of the power MOSFET and the reverse recovery current of the diode. The loss and EMI noise can be considerably reduced in this way. Brief operational principle and experimental results are included to verify the usefulness.

• 한국연소학회:학술대회논문집
• /
• 2003.05a
• /
• pp.75-83
• /
• 2003

Diode laser absorption system is advantageous of their non-invasive nature, fast response time, high sensitivity and real-time measurement capability. Furthermore, recent advances in room-temperature, near-IR and visible diode laser sources for telecommunication, optical data storage applications are enabling combustion diagnostics system based on diode laser absorption spectroscopy. So, combined with fiber-optics and high sensitive detection strategies, compact and portable sensor system are now appearing for a variety of applications. The objective of this research is to take advantage of distributed feed-back diode laser and develope new gas sensing system. It experimentally found out that the wavelength, power characteristics as a function of injection current and temperature. In addition to direct absorption and wavelength modulation spectroscopy have been demonstrated in these experiments and have a bright prospect to this diode laser system.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.28 no.1
• /
• pp.59-67
• /
• 2023

This paper explores the variation of DC-Link current ripple analysis in terms of duty cycle and phase angle of Multi-phase/Multi-stage boost converter. A 2-Stage/1-Stage boost converter DC-Link current is used to determine the difference between the 1st stage diode current and the 2nd stage inductor current. Each stage boost converter diode and inductor current is subordinate to the phase angle and duty cycle. The magnitude of the ripple current is variable according to phase angle and duty cycle. The analysis results are verified by variation of DC-Link current ripple using a 1kW typical 2-stage/1-stage boost converter.

• Journal of the Korean Electrochemical Society
• /
• v.3 no.1
• /
• pp.39-43
• /
• 2000

The light emitting diode (LED) was fabricated from n-type porous silicon. We investigated both the current-voltage characteristics of the LED with various electrode materials and changes of electroluminescence with applied current density. Also we probed changes in electroluminescence as a function of operation time at a given current. In order to Improve the contact area between the electrode material and porous silicon layer, we deposited indium on porous silicon layer by electroplating and investigated the electric characteristics of the LED and changes of electroluminescence.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.10
• /
• pp.581-586
• /
• 2002

To improve the current waveform of diode rectifiers, we propose a new operating principle for the voltage-doubler diode rectifiers. In the conventional voltage-doubler rectifier circuit, relatively large capacitors are used to boost the output voltage, while the proposed circuit uses smaller ones and a small reactor not to boost the output voltage but improve the input current waveform. A circuit design method is shown by experimentation and confirmed simulation. The experimental results of the proposed diode rectifier satisfies the harmonic guide lines. A high input power factor of 97(%) and an efficiency of 98[%] are also obtained. The new rectifier with no controlled switches meet the harmonic guide lines, resulting in a simple, reliable and low-cost at-to dc converters in comparison with the boost-type current-improving circuits. This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage. And this paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit is constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduction and the power factor improvement. Half pulse-width modulated (HPWM) inverter was explained compared with conventional pulse width modulated(PWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Journal of Power Electronics
• /
• v.3 no.4
• /
• pp.215-223
• /
• 2003

In this paper, a new zero-current-transition (ZCT) circuit cell is proposed. The main switch is turned-off under the zero current and zero voltage condition, and there is no additional current stress and voltage stress in the main switch and the main diode, respectively. The auxiliary switch is turned-off under the zero voltage condition, and the main diode is turned-on under the zero voltage condition. The resonant current required to obtain the ZCT condition is relatively small and regenerated to the input voltage source. The operational principles of a boost converter integrated with the proposed ZCT circuit cell are analyzed and verified by the simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.1
• /
• pp.9-15
• /
• 2021

In multi-string light-emitting diode (LED) driver system, current balancing is crucial because the brightness of LED is directly related to its forward current. This paper presents a novel LED current balancing topology using current-fed Z-source converter. With the proposed structure, currents flowing through two LED strings are automatically balanced owing to the charge-balance condition on capacitors. Operation of the proposed converter is simple and the proposed converter uses only one active switch and one diode. Moreover, low-side gate driving can be used to operate the active switch. To verify the operation of the proposed LED current balancing converter, a prototype is built and tested with different numbers of LEDs.

• 한국태양에너지학회:학술대회논문집
• /
• 2008.04a
• /
• pp.257-262
• /
• 2008

In this paper, we study the electric characteristics of shading effects in photovoltaic module in case of outdoor operation. When fabricating PV module, solar cells are connected serially to obtain the high voltage because of its low open circuit voltage. And total current is determined by lowest current among solar cells. When the shading happens on PV module's surface, the current of shaded solar cell determine the total current flow. Because of this, generally by-pass diode is installed on junction box. The bypass diode operate when revered and shaded solar cell's voltage is over 0.6 voltage. The reverse-biased solar cell gives reduced maximum power of PV module and might give negative effect on durability. So, adequate by-pass installation and selection is needed.