• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.147-148
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• 2006

Sl-Thyristor는 기존의 Power semlconductor인 단일 IGBT,MOSFET과 비교하여 높은 정격 전압과 대전류의 소호가 가능하며 빠른 turn on swithcing time을 가지는 특성이 있다. 하지만 게이트 드라이버를 이용한 Sl-Thyristor의 turn on 구동시에는 전압구동의 특성과 turn 0ff시에는 전류 구동의 특성에 가까운 구동 특성이 요구되기 때문에 스위칭 요구 특성에 맞는 게이트 드라이버의 설계 및 제어가 쉽지 않다. 본 논문은 펄스 파워 어플리케이션으로 Sl-Thyristor(PT-201 5kV/100A)를 사용하여 pulsed power moduiator용 Sl-Thyristor의 게이트 드라이버의 요구인 빠른 turn on switching 특성과 turn off 시 Si-Thyristor 내의 전하를 빨리 제거하기 위한 조건을 제시하고 있다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.531-537
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• 2011

This paper proposes a finite element method (FEM)-based model of an interior permanent magnet (IPM) type BLDC motor having stator inter-turn faults. For more realistic simulation studies, the magnetic non-linearity is also considered in proposed model. And the simulation data are verified through experiment. By integrating the developed model with a current-controlled voltage source inverter (CCVSI) model, the characteristics of an inter-turn fault operated by six-switched inverter are investigated considering the speed control. And the circulating current, which is induced by magnetic linkage flux originated from PM, was analyzed from the view point of distortion of air-gap magnetic flux distribution caused deterioration of their torque.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1527-1536
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• 2014

This paper investigates the optimal values of turn-on and turn-off angles, and ratio of flux linkage at turn-off angle and peak phase current positions of optimal control for accomplishing maximum output power in an 8/6 Switched Reluctance Generator (8/6 SRG). Phase current waveform is analyzed to determine optimal excitation angles (optimal turn-on and turn-off angles) of the SRG for maximum output power which is applied from a nonlinear magnetization curve in terms of control variables (dc bus voltage, shaft speed, and excitation angles). The optimal excitation angles in single pulse mode of operation are proposed via the analytical model. Simulated and experimental results have verified the accuracy of the analytical model.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1356-1361
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• 2008

A switched reluctance generator(SRG) has simple magnetic structure, and needs simple power electronic driving circuit. But, a SRG are no windings or permanent magnets on the rotor, and there are concentrated windings placed around each salient pole on the stator. Because of the characteristics of time-sharing excitation, the control of SRG is very flexible. And there are several parameters for controlling SRG, such as switch turn-on angle, switch turn-off angle, and exciting voltage and controlling mode, all these will affect the generation greatly. A SRG has positive torque at increasing inductance region and negative torque at decreasing inductance region. In this paper, we studied characteristics about the switch turn-on and off angles according to switch method for constant output voltage of the fixed speed SRG. It is the acoustic noise and torque ripple characteristics. Characteristics for a switch angle and method are presented by experiment using a 50W SRG with 12/8 poles.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.181-184
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• 2017

This study analyzes the turn-on and turn-off transients of a metal-oxide-semiconductor field-effect transistor (MOSFET) with high-switching frequency systems. In these systems, the voltage distortion becomes serious at the output terminal of a Vienna rectifier by the turn-off delay of the MOSFET. The current has low-order harmonics through this voltage distortion. This paper describes the transient of the turn-off that causes the voltage distortion. The algorithm for reducing the sixth harmonic using a proportional-resonance controller is proposed to improve the current distortion without complex calculation for compensation. The reduction of the current distortion by high-switching frequency is verified by experiment with the 2.5-kW prototype Vienna rectifier.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.501-506
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• 2022

Long turn-off time limits high frequency operation of Bipolar Junction Transistors (BJTs). Turn-off time decreases with increases in the recombination rate of minority carriers at switching transients. Fast neutron irradiation on a Si BJT incurs lattice damages owing to the displacement of silicon atoms. The lattice damages increase the recombination rate of injected holes with electrons, and decrease the hole lifetime in the base region of pnp Si BJT. Fast neutrons generated from a beryllium target with 30 MeV protons by an MC-50 cyclotron were irradiated onto pnp Si BJTs in experiment. The experimental results show that the turn-off time, including the storage time and fall time, decreases with increases in fast neutron fluence. Additionally, it is confirmed that the base current increases, and the collector current and base-to-collector current amplification ratio decrease due to fast neutron irradiation.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3334-3341
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• 2023

We studied the irradiation effects of fast neutron generated by a 30 MeV cyclotron on the electrical and switching characteristics of NPT-IGBT devices. Fast neutron fluence ranges from 2.7 × 10⁹ to 1.82 × 10¹³ n/cm². Electrical characteristics of the IGBT device such as I-V, forward voltage drop and additionally switching characteristics of turn-on and -off were measured. As the neutron fluence increased, the device's threshold voltage decreased, the forward voltage drop increased significantly, and the turn-on and turn-off time became faster. In particular, the delay time of turn-on switching was improved by about 35% to a maximum of about 39.68 ns, and that of turn-off switching was also reduced by about 40%-84.89 ns, showing a faster switching.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.663-668
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• 2010

In driving a car, turns such as left turns, right turns, or u-turns, make the speed of the car decrease considerably. A more straight path, therefore, is probably faster to arrive at the destination than zig-zag path with same distance. In this paper, we have newly proposed the turn heuristic to make more straight path. The path navigation algorithm with turn heuristic(called as TA* algorithm) could enhance the straightness of a path by putting the turned-edges to the turn cost. It requires higher cost to use TA* algorithm than traditional A* algorithm because the straight-edge first searching have increased the search space. We have improved the TA* algorithm into the variable TA* algorithm(called as VTA* algorithm) which adopt the turn-heuristic during the a portion of the whole path.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.477-482
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• 2012

This paper describes a new rotor position sensorless control method for SRM drives based on an improved simplified flux linkage method. In the traditional simplified flux linkage method, every phases take turns conduction and current chopping control method is used. Every phases take turns conduction means turning on the incoming working phase while turning off the working phase. This conduction mode causes coupling between turn-on and turn-off angles, which goes against optimal efficiency or torque ripple minimization with sensorless speed control. In the improved simplified flux linkage method, turn-off angle is calculated by flux loop, the turn-on angle can be given arbitrarily and has no relations with the turn-off angle, and the current chopping control method is used. The speed and rotor position can be estimated then. Finally, a sensorless SRM speed control system and an experiment platform with DSP are built and validity of this method is confirmed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.365-373
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• 2018

In this paper, inter-turn fault diagnosis of the interior permanent magnet synchronous motor (IPMSM) is performed in offline state by linking the finite element analysis (FEA) tool and control simulation tool. In order to diagnose the inter-turn fault, it is important to select the current value to determine the fault. First, the basic principles for inter-turn fault diagnosis of IPMSM are explained and co-analysis model for fault diagnosis is constructed. Further, in order to select the appropriate high frequency voltage, the change of the current value to be judged as failure was analyzed at various voltage and frequency conditions, and the change of the current value according to the number of the failed windings was analyzed. Finally, the current value to be judged as failure is selected.