• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.6
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• pp.600-606
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• 1992

The series connection of power switching semiconductor elements is essential when a high voltage converter is made, so researches are being conducted to further develop this technology. In the series connection of power switching semiconductor elements, the main problem is that simultaneous conduction at turn-on and simultaneous blocking at turn-off together with voltage balancing are unattainable because of the difference of their switching characteristics. In this paper a novel series connection algorithm is proposed, which can implement not only the synchronization of the points of turn-on and turn-off time but the dynamic voltage balancing in spite of the difference of each switching characteristics. The proposed method is that the compensated control signal is attained from the voltage feedback signal and applied to the series-connected power transistors independently. Computer simulation and experimental results verify its validity.

• 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.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.701-704
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• 2000

A SRG(Switched Reluctance Generator) has many advantages such as efficiency simple controllability low cost and robustness compared with outer machines. But the theories that have been adopted as SRG control methods up to the present are complicated. This paper proposes a simple control methods using PID which controls only a turn-off angle while making turn-on angle signals of SRG constant. controlling the voltage differences between the reference and the real value and calculating the proper turn-off angle of the load variations can implement to keep the output voltage constant. the control method suggested in this paper enhances the efficiency of this system and simplifies the hardware and software by using only the voltage and speed sensors. The proposed method is verified by experiment

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.668-676
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• 1998

A passive energy recovery snubber for high-power-factor boost rectifier, in which the main switch is described in terms of the equivalent circuits that are operational during turn-on and turn-off sequences. These equivalent circuits are analyzed so that the overshoot voltage across the main switch, the snubber current, and the turn-off transition time can be predicted analytically. The main switch combined with proposed snubber can be turned on with zero current and turned off at limited voltage stress. The high-power-factor boost rectifier with proposed snubber is implemented, and the experimental results are presented to confirm the validity of proposed snubber.

• Proceedings of the KIEE Conference
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• summer
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• pp.989-991
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• 2004

There are many elements that affect the average torque of the single phase SRM. It is related with the stator and rotor pole arcs, the dwell angle of the exciting current, the turn on/off angle, etc., Most of all, the turn on/off angle is affect the design procedure of the driving and control circuit. So, in this study, it is intend to analyze the effect that the variations of the turn on/off angle affects the average torque. and then this analyses will be used to design the control driver of the single phase SRM.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.409-412
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• 1990

Series connection of power switching semiconductor elements is unavoidable when a high voltage convertor is aimed. However, it is important to equalize distribution of turn-off voltage because the switching elements have different characteristics. In this paper optimal switching control algorithm is proposed so that series connected poker switching semiconductor elements can be always switched simultaneous turn-on and turn-off.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.222-230
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• 1998

This paper proposes a new gate drive circuit for high power IGBTs which can reduce the harmful effect of reverse recovery current at turn-on and actively suppress the overvoltage across the driven IGBT at turn-off without a snubber circuit. The turn-on scheme decreases the rising rate of the collector current by inereasing the input capacitance at turn-on transient when the gate-emitter voltage goes above threshold voltage. It results in soft transient of the reverse recovery current with no variation in turn-on delay time. The turn-off driving scheme has adaptive feature to the amplitude of collector current, so that the overvoltage can be limited much effectively at the fault collector current. Experimental results under various normal and fault conditions prove the effectiveness of the proposed circuit.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1061-1062
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• 2006

This paper represent improved On-line Turn off, commutation Angle control schemes for switched reluctance motors based on current control. For the purpose of the finding optimal commutation switching angle point, it is utilized turn on and turn off position calculation with inductance vs. current vs. flux linkage analysis method. The goal of proposed paper is the maximization of the energy conversion per stroke and maximizing efficiency and obtaining approximately flat-topped current waveform. The proposed control scheme is demonstrated on a simulation experimental result.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.99-104
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• 1999

The large scale industry needs high voltage converters. Therefore series connection of power semiconductor devices is necessary. It is important to prevent the overvoltage from being induced across a device above ratings by the proper voltage balancing in the field of IGBT series connection. In addition, the overvoltage induced by a stray inductance has to be limited in the high power circuit. This paper proposes a new gate control scheme which can balance the voltage properly and limit the overshoot by controlling the slope of collector voltage under the turn-off transient in the series connected IGBTs. The proposed gate control scheme which senses the collector voltage and controls the gate signal actively limits the overvoltage. The new series connected IGBT gate driver is made and its validity is verified by the experimental results in the series connected IGBT circuit.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.4
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• pp.207-213
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• 2002

The paper introduces a switched reluctance motor drive system based on an 80C31 and an Intel 80C 196KB single-chip microprocessor control. Advance schemes are used in turn-on and turn-off angles with the power converter's main switches during traction and regenerative braking. The principles of traction speed control and braking torque control are given. The hardware and software patterns in the 80c31 and the Intel 80C196KB single-chip microprocessor control system are also presented.