• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.887-888
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• 2006

Switched Reluctance Motor(SRM) is rotated by reluctance force generated between rotor pole and stator pole. So SRM must be switched by exciting current according to rotor position. but SRM takes the advantages of high speed driving and very simple structure. The single phase SRM can not be start by itself and torque ripple is generated more than multi-phase SRM. But mechanical structure and driver is simpler than multi-phase SRM. The single phase SRM driver is composed with the absolute encoder and DSP to control exciting section and current, and is supplied by constant voltage. So The paper is intend to measure the speed charactrer of double silent pole type SRM by using the unipolar driving curcuit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.12
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• pp.8-14
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• 2015

An effective way to ensure that LEDs produce wanted light output is to use a current driving topology, because the brightness of LEDs is directly related to their current. However, this topology may lead to the lifetime shortening of a illumination system because over-currents may flow through non-damaged LEDs in case some LEDs are damaged. This paper presents an adaptive current control circuits for LEDs, which protect LEDs in a good state by limiting the driving currents according to the number of damaged ones. The proposed control circuits consist of a simple constant-current driver and a micro-controller which monitors the voltage of LED array without any auxiliary current sensors for fault diagnosis. And the driving current is automatically controlled into 6-levels according to the number of failures.

• Journal of Power Electronics
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• v.12 no.5
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• pp.715-722
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• 2012

New discrete time domain models for the peak current controlled (PCC) power LED drivers in continuous conduction mode include for the first time the effects of the time delay in the pulse-width-modulator. Realistic amounts of time delay are found to have significant effects on the average output LED current and on the critical inductor value at the boundary between the two conduction modes. Especially, the time delay can provide an accurate LED current for the PCC buck converter with a wide input voltage. The models can also predict the critical inductor value at the mode boundary as functions of the input voltage and the time delay. The overshoot of the peak inductor current due to the time delay results in the increase of the average output current and the reduction of the critical inductor value at the mode boundary in all converters. Experimental results are presented for the PCC buck LED driver with constant-frequency controller.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.139-143
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• 2004

This paper presents a method that the engine oil condition is detected using a natural convection heat transfer in a engine oil. A sensor circuit maintains a constant temperature difference between a heat plate and engine oil for detecting a natural convection heat transfer rate on the constant temperature. The natural convection heat transfer rate is measured by a current through the heat plate of the sensor circuit. The sensor is tested by a fresh oil. 6,000 km and 10,000 km driven oil in the oil temperature range from $20^{\circ}C$ to $100^{\circ}C$. In the experimental result, when the current through the heat plate is altered by variation of a engine oil temperature and flows driven oil more than fresh oil, the sensor could inform a engine oil deterioration to a car driver.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1130-1139
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• 2012

This paper proposes a LED lighting system using integrated power system composed of bridgeless PFC, LLC DC-DC transformer, and dimmable constant current LED driver module. The proposed LED lighting system features high efficiency, high power factor, and dimming capability. In order to verify the validity of the proposed system, the 2kW prototype system was built and tested. From the experimental results, it was confirmed that the maximun efficiency of 92.6% and maximum power factor of 99.7% can be achieved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.110-113
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• 2000

In general, speed control method of the elevator system has used motor pole change type or motor primary voltage control type. But it will change to vector control type in order to increase it's reliability, riding comfort and decrease material cost. It is the conception of vector control type in order to increase it's reliability, riding comfort and decrease material cost. It is the conception of vector control that primary current of the induction motor be controlled independently with magnetizing current(field current of DC motor) and torque current(armature current of DC motor). In this paper, by analyzing the effect of the time constant variation of rotor of the induction motor on the slip frequency type indirect vector control, a drive system for the motor will be constructed using a fuzzy slip frequency type indirect vector controller with fuzzy control method for estimating the vector time constant in the slip frequency type indirect vector control. The goal of this study is to enabling even more efficient speed control by constructing on elevator driver based on the newly developed drive system.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.347-349
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• 2013

This paper describes analysis and calculation of line frequency ripple current according to output capacitor value and effects of LED connection in the single stage flyback converter with high power factor. The low frequency output ripple current delivered from single stage converter has been analyzed in detail and the method evaluating parasitic resistance included in LED has been provided. In order to verify the equation derived in this paper, the single stage flyback converter has been designed with constant output current regulation with DCM operation. Experiments were conducted with different LED load structures to analyze the effect of LED parasitic resistance on output ripple current. As test results, the calculation can provide guide line to select capacitor values depending on output ripple current and LED characteristics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1797-1805
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• 2012

In this paper, Power LED(Light Emitting Diodes) is studied to driver as a new lighting system in the spotlight, replacing a large existing lighting system with fluorescent and incandescent lighting. To take advantage a variety of DC power as the boost DC-DC converter design specifications through the inductor L and capacitor C through PSPICE to calculate the best estimate of the value. Converter's switching frequency is 50[kHz], the first Duty Rate was made to increase gradually depending on the value of the detection were, 10[%] in the output voltage. As a result, the simulated Boost Power LED driver characteristics is in comparison with the design specifications, 5[%] or less as the error was approximated. So, when input 15[V] were offered, a stable output 24[V] were obtained, and Dimming Control through the adjustment of brightness and current consumption were obtained to possible result.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.71-76
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• 2022

Since brightness is proportional to the operating current, a method of connecting several LEDs in series and driving with a constant current source is widely used for driving circuits of LED lights. Because several LEDs are connected in series, if some LEDs open due to a fault, the current path is broken and all other LEDs connected in series are turned off. In this paper, we designed a circuit to solve this problem by connecting a Zener diode having a breakdown voltage of about 0.4V higher than the LED operating voltage in parallel with each LED to create a current bypass in case of LED failure. Through simulations and experiments, it was confirmed that the current of the Zener diode hardly flows when the LED is operating normally, and that the Zener diode stably operates as a current bypass when the LED fails.

• Journal of Broadcast Engineering
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• v.21 no.5
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• pp.760-769
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• 2016

This paper proposes a hybrid LED driving circuit and its control method for extension of the color gamut of LED. The proposed hybrid LED driving circuit provides the constant current by switching regulation in the high current and by linear regulation in the low current through LED. Furthermore, the magnitudes of the high current and low current were controlled by CC(Continuous Current) control method and PWM(Pulse Width Modulation) control method, respectively. We experimentally confirmed that the current through RGB LED is linearly controlled to 2% maximum current ratio by varying PWM in the proposed driving circuit and control method. As a result of the measurement of the output light color in CIE1976 chromaticity coordinates, we confirmed that the color, which not be expressed by the existing method, uniformly expressed. We confirmed that the color, which can not be expressed by the existing method, was uniformly output and verified that the color gamut was expanded by the low current controlled by the proposed driving circuit and control method.