• Nuclear Engineering and Technology
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• 제36권4호
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• pp.357-363
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• 2004

A prototype long pulse ion source was developed, and the beam extraction experiments of the ion source were carried out at the Neutral Beam Test Stand (NBTS) of the Korea Superconducting Tokamak Advanced Research (KSTAR). The ion source consists of a magnetic bucket plasma generator, with multi-pole cusp fields, and a set of tetrode accelerators with circular apertures. Design requirements for the ion source were a 120kV/65A deuterium beam and a 300 s pulse length. Arc discharges of the plasma generator were controlled by using the emission-limited mode, in turn controlled by the applied heating voltage of the cathode filaments. Stable and efficient arc plasmas with a maximum arc power of 100 kW were produced using the constant power mode operation of an arc power supply. A maximum ion density of $8.3{\times}10^{11}\;cm^{-3}$ was obtained by using electrostatic probes, and an optimum arc efficiency of 0.46 A/kW was estimated. The accelerating and decelerating voltages were applied repeatedly, using the re-triggering mode operation of the high voltage switches during a beam pulse, when beam disruptions occurred. The decelerating voltage was always applied prior to the accelerating voltage, to suppress effectively the back-streaming electrons produced at the time of an initial beam formation, by the pre-programmed fast-switch control system. A maximum beam power of 0.9 MW (i.e. $70\;kV{\times}12.5\;A$) with hydrogen was measured for a pulse duration of 0.8 s. Optimum beam perveance, deduced from the ratio of the gradient grid current to the total beam current, was $0.7\;{\mu}perv$. Stable beams for a long pulse duration of $5{\sim}10\;s$ were tested at low accelerating voltages.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.385-386
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• 2014

본 논문에서는 자심 테슬라 변압기를 이용한 400kV급 소형 고전압 펄스 발생기를 개발하였다. 테슬라 변압기의 효율 및 출력전압 향상을 위해 4분할 적층 원통형 자심 구조를 새롭게 제안 하였다. 제안 된 자심 구조를 적용하여 테슬라 변압기를 제작 한 결과, 최대 출력전압 425kV, 에너지 변환 효율 50%를 확인하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.295-300
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• 2001

A variety of high voltage DC power supplies employing the high frequency inverter are difficult to achieve soft switching considering a quick response and no overshoot response under the wide load variation ranges which are used in medical-use x-ray high voltage generator from 20kV to 150kV in the output voltage and from 0.5mA to 1250mA, respectively. The authors develops soft switching high voltage DC power supply designed for x-ray power generator applications, which uses series resonant inverter circuit topology with a multistage voltage multiplier instead of a conventional high voltage diode rectifier connected to the second-side of a high-voltage transformer with a large turn ratio. A constant on-time dual mode frequency control scheme operating under a principle of zero-current soft switching commutation is described. Introducing the multistage voltage multiplier, the secondary transformer turn-numbers and stray capacitance of high-voltage transformer is effective to be greatly reduced. It is proved that the proposed high-voltage converter topology with dual mode frequency modulation mode control scheme is able to be the transient response and steady-state performance in high-voltage x-ray tube load. The effectiveness of this high voltage converter is evaluated and discussed on the basis of simulation analysis and observed data in experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1755-1757
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• 1998

Pulse transformers have been developed to apply for pulsed power technology as an alternative of a Marx generator. To obtain repetitive pulsed power generation, it is necessary to observe the rising time of output of pulse transformer. In this paper, using the equivalent circuit, The rising wave of output of pulse transformer is simulated for various input wave by using the Electromagnetic transient program(EMTP).

• Journal of Power Electronics
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• 제18권3호
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• pp.789-801
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• 2018

Model predictive direct power control (MPDPC) is a widely recognized high-performance control strategy for a three-phase grid-connected pulse width modulation (PWM) rectifier. Unlike those of conventional grid-connected PWM rectifiers, the active and reactive powers of permanent magnet synchronous generator (PMSG)-connected PWM rectifiers, which are used in electromagnetic transmitters, cannot be calculated as the product of voltage and current because the back electromotive force (EMF) of the generator cannot be measured directly. In this study, the predictive power model of the rectifier is obtained by analyzing the relationship among flux, back EMF, active/reactive power, converter voltage, and stator current of the generator. The concept of duty cycle control in the proposed MPDPC is introduced by allocating a fraction of the control period for a nonzero vector and rest time for a zero vector. When nonzero vectors and their duration in the predefined cost function are simultaneously evaluated, the global power ripple minimization is obtained. Simulation and experimental results prove that the proposed MPDPC strategy with duty cycle control for the PMSG-connected PWM rectifier can achieve better control performance than the conventional MPDPC-SVM with grid-connected PWM rectifier.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1710-1713
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• 2002

Recently, the pulsed power system has been used to many applications. Such as remediation of environmental hazards, food sterilization, air pollution control E/P (Electrostatic Precipitator), DeNOx/DeSOx power system, ozone generator, high energy physics, and other power source applications. A pulse energy efficiency for load depends on the rising time, peak value. Pulse duration and impedance matching etc. The pulsed power system generally required for short pulse duration and high peak value was forced to consider its volume and economy. In this paper, we investigated operating characteristics of the CO2 laser using an inductively pulsed power system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1574-1575
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• 2011

The application of a pulsed power system is being extended to an environmental and industrial field. The non-destructive gaseous pollutants from industrial plants such as power generation plants and incinerators can be processed by applying high voltage pulses with a fast rising time (a few nanoseconds) and short duration (nano to microseconds) in a pulsed corona discharge reactor. The pulsed plasma generator with a triggered switch has been developed. Its corona current in load can be adjusted by applied voltage and repetition rate. We investigated the performance of the pulsed plasma generator by analyzing the concentration of ozone in small reactor. This paper describes the electrical characteristics of the pulse generator with a voltage of 30 kV at repetition rate of 50 PPS. In addition, we briefly discuss a configuration of the system and initial test results.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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• pp.372-378
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• 2012

This paper deals with a 3-phase voltage disturbance generator for a performance test of custom power devices such as dynamic voltage restorers (DVR), dynamic uninterruptable power supplies (UPS), etc. The operating principle of the proposed circuit is described in each mode of voltage sag, swell, outage, and unbalance. The main components of the proposed disturbance generator are silicone controlled rectifier (SCR) thyristors, variable autotransformers, and transformers. Therefore, the disturbance generator can be implemented with a considerably low cost compared to the conventional pulse width modified (PWM) inverter and converter type generators. Furthermore, it has good features of high reliability with simple structure, high efficiency caused by no PWM switching of the SCR thyristors, and easy control with a wide variation range. To verify the validity of the proposed scheme, simulations and experiments are carried out.

• 전기학회논문지P
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• 제58권4호
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• pp.588-591
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• 2009

We had experimental studies of microwave output generator. We experimented with a corrugate-shped K-band slow wave guide in the backward wave oscillator. It generated output 표 interaction between electron beam's generation and magnetic field. We estimated oscillation frequency at 24GHz by changing propagation velocity and group velocity. We identified movement by second harmonic of Cherencov interaction and slow cyclotron mode. In our study we achieved oscillation stabilization, generation of long pulse, improvement of oscillation efficiency and output.

• 한국전기전자재료학회논문지
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• 제19권6호
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• pp.591-598
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• 2006

The research was tried to investigate the hydrogen generation from water by the pulsed power plasma process. Hydrogen was generated by way of the electrical pulse power discharge process with the ultrasonic wave. The yield on the hydrogen generation was also studied with and without operating the ultrasonic generator, in which the applied high voltage was varied from 10 kV to 15 kV. Nitrogen and argon gases were used as working gases. As the results, the generation yield using the pure nitrogen gas is better than argon and mixed gases such as argon and nitrogen. Hydrogen concentration are significantly increased when the ultrasonic generator was operated with the electrical discharge simultaneously. It is increased with increasing the applied ultrasonic level as well.