• 전기의세계
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• v.28 no.12
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• pp.41-45
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• 1979

Improvement of power factor is achieved by reactive-current compensation, connecting power condenser to the circuit. This paper describes a method of reactive-current compensation, employing thyristor switching of capacitor banks without any breaker. This method reduces supply transients to the minimum by means of connecting condenser, because thyristor is triggered at zero point in condenser current. The reactive current detection and the experimental system to trigger thyristor at appropriate moment are given. IThe results show the fast reactive-current compensation on the condition of minimum transient.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.159-164
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• 2010

We experiment to analyze on current limiting and recovery characteristics of trigger type SFCL as the composition of the contact. Generally, some superconductor of SFCL is relatively largely loaded due to limit the fault current by oneself and recovery time is affected until the fault cleared. However, in the fault, the proposal trigger type SFCL transfer the fault current to current limiting reactor(CLR) using power switch so it could reduce the recovery time and load of the superconductor. However, because of applying the additional power switches, that could generate some power loss. Therefore, to solve this problem, we proposed the composition method of the double contact for a trigger type SFCL and analyzed on current limiting and recovery characteristics for ones.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.138-139
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• 2017

This paper describes the design and implementation of a trigger circuit which can be series connected with main pulse circuit for a xenon flash lamp driver. For generating high voltage, the trigger circuit is designed as an inductive energy storage pulsed power modulator with 2 state step-up circuit consisting of a boost converter and a flyback circuit. In order to guarantee pulse width, a resonant capacitor on the output side of the flyback circuit is designed. This capacitor limits the output voltage to protect the flyback switch. In addition, to protect another power supply of xenon flash lamp driver from trigger pulse, the high voltage transformer which can carry the full current of main pulse is designed. To verify the proposed design, the trigger circuit is developed with the specification of maximum 23 kV, 0.6 J/pulse output and tested with a xenon flash lamp driver consisting of a main pulse circuit and a simmer circuit.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2189-2191
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• 1999

To improve the reliability of the klystron-modulator systems, the stable operations of the thyratron an important factor of the system are required. The thyratron always has a possibility of self-fire according to the conditions of the applied high voltage and this induces the system fault. Therefore a command charging method was introduced to reduce the applied tim8 of the high voltage into the thyratron. The high voltage switch used in the command charging method is the SCR (1.6 kV, 50A) and consists of 10 SCRs in series to discharge 10 kV. A pulse transformer was used to apply the trigger pulse. The objectives of this research are the fabrication of the semiconductor switch and the study of the experimental result of the operation characteristics of the high voltage semiconductor switch.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1859-1861
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• 2002

This paper attempts to discuss the pseudo-spark which is developed for high voltage and high current. The pseudo-spark switch is on the basic of the Paschen's law. The pseudo-spark switch fabricates the glass chamber. The pseudo-spark switch consists of hollow cathode, hollow anode, and trigger. The pseudo-spark switch is operated at the voltage of 20 kV and the pressure range of $20{\sim}80$ mtorr with He-gas. The switching current of the pseudo-spark switch was measured as 65 kA, and the duration of the pulse was about 100 ${\mu}s$. This paper describes the results of tests and the characteristics of the switch.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.905-915
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• 2015

Two PWM techniques using space vector pulse-width modulation (SVPWM) are proposed for a two-phase permanent magnet synchronous motor (PMSM) driven by a two-phase eight-switch inverter. A two-phase motor with two symmetric stator windings is usually driven by a two-phase four-, six-, or eight-switch inverter. Compared with a four- and six-switch inverter, a two-phase eight-switch inverter can achieve larger power output. For two-phase motor drives, the SVPWM technique achieves more efficient DC bus voltage utilization and less harmonic distortion of the output voltage. For a two-phase PMSM fed by a two-phase eight-switch inverter under a normal SVPWM scheme, each of the eight PWM trigger signals for the inverter have to be changed twice in a cycle, causing a higher PWM frequency. Based on the normal SVPWM scheme, two effective SVPWM schemes are investigated in order to reduce the PWM frequency by rearranging four comparison values, while achieving the same function as the normal PWM scheme. A detailed explanation of the normal and two proposed SVPWM schemes is illustrated in the paper. The experimental results demonstrate that the proposed schemes achieve a better steady performance with lower switching losses compared with the normal scheme.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.128-130
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• 1995

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.205-208
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• 2002

The single phase induction motor(SPIM) with two windings, main and auxiliary winding, is widely used due to ruggedness, low maintenance and simplicity of construction. There are several ways of starting single phase induction motor. The most common method is to use centrifugal switch that is connected in series with a capacitor. But the centrifugal switch that is the external starting system has many problems. In this paper, we use triac to overcome defects that happen by centrifugal switch, Also we used inductor that connected with main winding to get a gate trigger voltage signal. Experiments are focused on a capacitor starling single phase induction motor.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.211-212
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• 1998

In this experiment, we developed a mind switching device which uses $\alpha$-wave with its amplitude varying between the eye-open and closed states. If the subject closes eyes, the switch toggles with a small delay. The circuit consists of an amplifier, a filter and a switch. An instrument amplifier is used fur high CMRR and for high input impedance. An 8th order Butterworth filter was able to reduce noise satisfactorily. The signal is then converted to a DC level, and finally a Schmitt trigger was used to generate a switching pulse.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.216-219
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• 2003

Persistent Current Switch (PCS) is used in many superconducting magnet system. To apply the high-Tc superconductor in superconducting machine such as motor, generator, MAGLEV, MRI and NMR, the study on the persistent current mode should be performed. Because persistent current mode provide best stability and homogeneous characteristics to the superconducting machine. To stabilize the superconductor system, it is important to estimate the length of PCS. If the proper length of PCS is too short, it cause serious injury to system in fault state. So we calculated the optimal length of PCS in this paper.