• JSTS:Journal of Semiconductor Technology and Science
• /
• 제8권1호
• /
• pp.85-91
• /
• 2008

A Boost Power Factor Correction (PFC) Converter employing Zero Voltage Switching (ZVS) based Compound Active Clamping (CAC) technique is presented in this paper. An Electro Magnetic Interference (EMI) Filer is connected at the line side of the proposed converter to suppress Electro Magnetic Interference. The proposed converter can effectively reduce the losses caused by diode reverse recovery. Both the main switch and the auxiliary switch can achieve soft switching i.e. ZVS under certain condition. The parasitic oscillation caused by the parasitic capacitance of the boost diode is eliminated. The voltage on the main switch, the auxiliary switch and the boost diode are clamped. The principle of operation, design and simulation results are presented here. A prototype of the proposed converter is built and tested for low input voltage i.e. 15V AC supply and the experimental results are obtained. The power factor at the line side of the converter and the converter efficiency are improved using the proposed technique.

• ETRI Journal
• /
• 제36권6호
• /
• pp.881-888
• /
• 2014

This paper studies the magnetic coupling between two adjacent loop antennas that are parallel to each other in a plane and presents a new practical method to avoid the resulting magnetic coupling interference. The study focuses on the high frequency radio-frequency identification (RFID) system for casino applications, where several loop antennas are closely built into a game table to monitor gaming chips. In this case, neighboring loop antennas may severely interfere with each other by magnetic coupling, which leads to the malfunction of the RFID system. In this paper, we present a practical loop antenna with a new loop switch circuit for avoiding magnetic coupling. The loop switch circuit is integrated with a matching circuit and automatically operated by using an interrogating signal from a reader. We verified the validity of the proposed design by showing that an RFID reader with the proposed antenna can exactly and separately read the gaming chips placed on the different betting zones of a game table.

• Journal of Electrical Engineering and Technology
• /
• 제5권3호
• /
• pp.484-492
• /
• 2010

Magnetic switch is a kind of saturable inductor, which utilizes nonlinearity of the magnetization curve of ferromagnetic materials. The right understanding of the saturation phenomena, magnetic properties, voltage-time product, and switching characteristics of the magnetic switch is essential in designing the magnetic pulse compressor (MPC). In this paper, the historical background of research on the MPC, fundamental physical properties of the magnetic switches, and application fields of the MPC are presented. Further, an in-depth analysis of pulse compression in series and parallel MPCs is incorporated. As practical application examples, a series MPC used for water treatments and a parallel MPC used for pulsed electric field (PEF) inactivation of bacteria are cited.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1989년도 하계종합학술대회 논문집
• /
• pp.637-641
• /
• 1989

We have developed 3-stage of Magnetic Switch System based on the nonlinearities of ferromagnetic material used in the saturable inductor, and made experiment of parameter optimization and output stabilization of Magnetic Switch System. The cross-section and conductor burns of each satarable inductor were optimized 30 $cm^2$ 19.25 $cm^2$ 5, and 25 $cm^2$ 2, respectively. With this condition, 6.2 us [FWHM], 96 A pulse at first stage was compressed into 0.4 us[FWHM], 1.61 kA pulse at last stage. The current gain and compression ratio were 16.8, 17, respectively. ln addition, System output was stabilized with reset current of 6 A, 200 us.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.18-20
• /
• 2001

This paper describes are quenching chambers of three type for Magnetic Switch and analyzes electromagnetic blowout force acting on the arc using 3D finite element method we make prototype device of each model and establish characteristics of arc quenching by measuring arcing time. This paper compares electromagnetic blowout to inverse arcing time. As the result this proposes the improving method for arc quen performance in DC magnetic switch.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
• /
• pp.377-380
• /
• 2005

In this paper, accelerated stress test(AST) for Magnetic Switch (MS) are applied to assure specified reliability of the products. Magnetic contactor that functions with over-current relay is called MS. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. In this study, AST for product assembly are developed in order to improve the weak point so that increase the product reliability. Also we will show the basic information for the accelerated life test(ALT). The proposed AST results and procedures may be extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably. Finally the results of this study will contribute to improving reliability of products and strengthening competitiveness of our products in the world markets.

• 한국초전도ㆍ저온공학회논문지
• /
• 제14권3호
• /
• pp.53-59
• /
• 2012

Adiabatic demagnetization refrigerator (ADR) for hydrogen re-liquefaction operating between 24 K and 20 K has been designed. $Dy_{0.9}Gd_{0.1}Ni_2$, whose Curie temperature is 24 K, is selected as a magnetic refrigerant. The magnetic refrigerant powder is sintered with oxygen-free high purity copper (OFHC) powder to enhance its effective thermal conductivity as well as to achieve relatively high frequency. A perforated plate heat exchanger (PPHE) operated with forced convection is utilized as a heat switch. The forced convection heat switch is expected to have fast response relative to a conventional gas-gap heat switch. A conduction-cooled high Tc superconducting (HTS) magnet is employed to apply external magnetic field variation on a magnetic refrigerant. $2^{nd}$ generation GdBCO coated conductor HTS tape with Kapton$^{(R)}$ insulation (SUNAM Inc.) will be utilized for the HTS magnet. The magnetization and demagnetization processes are to be achieved by the AC operation of the HTS magnet. The designed magnetic field and target ramp rate of the HTS magnet are over 4 T with 180 A and 0.4 T/s, respectively. AC loss distribution on HTS magnet is theoretically estimated.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
• /
• pp.157-161
• /
• 2000

The electronic ballasts for low pressure discharge lamps are produced and commercialized. However, the electronic ballasts for high pressure lamps are now in progress because of poor reliability and high cost. The major case of troubles with electronic ballasts are thermal destruction of semiconductor output switches due to non ideal i-v characteristics of switch. The loss converts to heat and rises the temperature of switch and it increases proportionally to switching frequency and value of current and voltage. This study shows the variable frequency ballasts which can suppress the heating of switches efficiently. It is used for the limitation the switch current and the rising temperature of switch by impedance variation of lamp inductor. As a result, initial warm-up time of the proposed ballasts was faster than that of magnetic ballasts about 90 msec. Power factor of tested ballasts follow as ; input and output average of magnetic ballasts are 93 [%] and 86 [%], respectively, And proposed ballasts are 97 [%] and 99 [%], respectively.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 A
• /
• pp.354-356
• /
• 2004

This paper is the transient analysis for choosing the optimal SCR ratings of AC3 utilization category testing equipment(AC3 TE) used for electrical durability test for magnetic switch according to IEC60947-4 Annex B by utilizing EMTP -ATPDraw. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. The key cost of AC3 TE is the SCR ratings. The more decreases SCR ratings, the more decreased the cost is, but it is impossible to ensure the reliability. On the other hand, the more increases SCR ratings, the more increased the cost is. Thereupon, in this paper after the testing circuit is simulated by using EMTP-ATPDraw the SCR ratings will be applied in order to guarantee the testing reliability of PT&T(Power Testing and Technology institute in LG Industrial Systems Co.,Ltd.).

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.353-356
• /
• 2001

This paper describes an analysis of electromagnetic system of Magnetic Switch using 3D and 2D finite element method. The electromagnetic blowout force acting on the arc is obtained by 3D finite element method. So, we are researching the arc chamber for dc current using permanent magnet.