• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2001.11a
• /
• pp.109-113
• /
• 2001

A high-efficiency electronic ballast for HID lamps is presented. The ballast consists of a PFC and a resonant inverter. To reduce losses of ballast,7C link voltage is determined by taking into account the peak voltage of lamp and a filter-inductor at Bridge diode is employed in order to remove harmonics from PFC. The flux density B$_{m}$ is kept 0.2[T] on all of inductors. A small inductor is connected in series with an electrolytic capacitor of PFC to be operated no high-frequency components. The acoustic resonance is eliminated using the spread spectrum technique. Electronic ballast for 250W metal-halide lamp is implemented and the experimental results show that 97% efficiency, no acoustic resonance and low conducted EMI level.l.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.2
• /
• pp.209-216
• /
• 2013

In this paper, we design and analyze digital retrodirective array antenna (RDA) system in 60GHz wireless communication for low power consumption and high quality. Digital RDA can automatically make beam toward source without information about the direction of incoming signal, this system is able to do low power communication thanks to increased signal to interference noise ratio (SINR) because making the beam toward source can reduce interference signals. The frequency offset seriously arises when millimetric wave band like 60GHz is used to communicate for high-speed transmission. The proposed system is robustly designed to frequency offset through designing digital phase lock loop in order to solve the problem of frequency offset. In this paper, we analyze the performance of the proposed system according to the number of array antenna and frequency offset. striking space.

• Journal of Institute of Control, Robotics and Systems
• /
• v.10 no.3
• /
• pp.286-293
• /
• 2004

This paper presents the result of a study on the starter control for a turbo generator. Because a starter in gear box type turbo-generator system is composed of gearbox and brush DC motor, it should be replaced with High Speed Generator(HSG)) in HSG type Turbo-generator. There-ore, it is necessary to design a new starting algorithm and starter. In gearbox type system, brush DC motor is rotated to the designed speed using low voltage-high current battery power. After brush DC motor speed is increased to several times by gearbox, gas turbine engine can be rotated to designed starting speed. If we implement a starter with High Speed Generator(HSG), it is necessary to drive high-speed generator to high-speed motor. High-speed generator with permanent magnet on rotor has a low leakage inductance fur driving high-speed rotation, and it is necessary high DC link voltage for inverter when High-speed generator is driven to high speed. This paper presents result of development of the boost converter for converting high voltage DC from low battery voltage and design of the inverter for controlling a high frequency current to be injected to motor winding. Also, we show performance of the designed starter by driving the turbo generator.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.10
• /
• pp.1-7
• /
• 2017

This study investigates the high-frequency heat treatment characteristics with the distance between a coil and SCM440 parts for an automobile. Global automobile makers are focusing on research to develop high-performance automobiles with improved fuel efficiency and lower emissions in accordance with consumer demand and environmental policies. However, most research on high-frequency heat treatment has been experimental, and it is very difficult to obtain high-frequency heat treatment conditions for a specific product. Therefore, all the conditions of high-frequency heat treatment except the distance between a coil and SCM440 parts were kept the same. As a result, the optimized distance between the coil and SCM440 parts was observed to be 1-2 mm. When the distance between the coil and SCM440 parts was over 3 mm, the effective case hardness depth and total case hardness depth did not satisfy the standards.

• Journal of Power Electronics
• /
• v.4 no.4
• /
• pp.237-245
• /
• 2004

In this paper, a two-switch high frequency flyback transformer linked zero voltage soft switching PWM DC-DC power converter implemented for distributed DC- feeding power conditioning supplies is proposed and discussed. This switch mode power converter circuit is mainly based on two main active power semiconductor switches and a main flyback high frequency transformer linked DC-DC converter in which, two passive lossless quasi-resonant snubbers with pulse current regeneration loops for energy recovery to the DC supply voltages composed of a three winding auxiliary high frequency pulse transformer, auxiliary capacitors and auxiliary diodes for inductive energy recovery discharge blocking due to snubber capacitors are introduced to achieve zero voltage soft switching from light to full load conditions. It is clarified that the passive resonant snubber-assisted soft switching PWM DC-DC power converter has some advantages such as simple circuit configuration, low cost, simple control scheme, high efficiency and lowered noises due to the soft switching commutation. Its operating principle is also described using each mode equivalent circuit. To determine the optimum resonant snubber circuit parameters, some practical design considerations are discussed and evaluated in this paper. Moreover, through experimentation the practical effectiveness of the proposed soft switching PWM DC-DC power converter using IGBTs is evaluated and compared with a hard switching PWM DC-DC power converter.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.4 no.5
• /
• pp.449-454
• /
• 1999

A new scheme of the automotive High Intensity Discharge (HlD) lamp ballast systems is proposed. The p proposed scheme consists of the high frequency IX DC converter and the low frequency DC-AC inverter, like t that the conventional HID ballast system. However, this system separates the input voltage of the ignitor from t the dc link voltage, which results in the use of lower voltage rating power devices for the HID lamp ballast s system, comparlu with convention띠 system. As a result, proposed system has a lower cost and higher e efficiency. This paper presents th$\varepsilon$ design and anlaysis of the propoSlU ballast and some 앉아、nmental results.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.217-221
• /
• 2001

This paper presents a new prototype of soft-switching DC-DC power converter with a high frequency transformer link which has two active power controlled switches in full bridge rectifier with capacitor input type smoothing filter. In this DC-DC converter, ZVS of the inverter in transformer primary side and ZCS of active rectifier area in secondary side can be completely achieved by taking advantage of parasitic inductor component of high-frequency transformer and loss less snubbing capacitors. Its operation principle and salient features are described. The steady-state operating characteristics of the proposed DC-DC power converter are illustrated and discussed on the basis of the simulation results in addition to the experimental ones obtained by 2kw-40kHz power converter breadboard set up.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.10 no.3
• /
• pp.233-240
• /
• 2005

In this paper, AC electric vehicle propulsion system(Converter/Inverter) using high power semiconductor, IPM is proposed. 2-Parallel operation of two PWM converter is adopted for increasing capacity of system and the harmonic content is eliminated by the phase shaft between two PWM converters switching phase. VVVF inverter control is used a mixed control algorithm, where the vector control strategy at low speed region and slip-frequency control strategy at high speed region. The proposed propulsion system is verified by experimental results with a 1,350kW converter and 1,100kVA inverter with four 210kW traction motors.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.10
• /
• pp.83-88
• /
• 2000

multi-beam optical drive is a method to improve the data transfer rate for the optical disc systems by parallel recording and reading on neighboring multi-tracks. In this paper, the beam rotating actuator, which is necessary for the multi-bean optical disc drive to from beam spots on multi-tracks simultaneously, has been developed. The Voice Coil Motor is used as a drive mechanism for high resolution and small size of the actuator. And rotating guide based on link structure is designed for frictionless and axisless rotation of rotating part including dove prism and for rotating in axis of geometric center of dove prism. The characteristics of the actuator are experimented by laser vibrometer, Polytec OFV1102 and a dynamic analyzer, HP35670A. It shows that the actuator has good linearity, rotating range $\pm0.34^\circ$, minimum rotating angle $0.0066^\circ$and natural frequency 113.9Hz. Therefore the actuator can be applied in a multi-beam optical disc system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.9
• /
• pp.47-56
• /
• 2012

This research is to develop satiable battery charger with a variety of capacity and voltage specifications of battery. For this, voltage or current were controlled through buck converter which is DC voltage that already received three-phase at primary side and passed bridge rectifier diode. And, it was comprised of full-bridge converter and HFTR for insulation and a square wave AC. The transformer primary side was comprised in series to divide certain charging current and the secondly side was comprised of 6 fixed transformers so that they can generate certain amount of power and various output voltage through relay parallel compound 6 DC Link outputs. To confirm such structure's verification and validity, simulation with PSIM was conducted, and validity of proposed variable charger system was verified through 3kW stack production.