• Journal of Power Electronics
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• v.17 no.1
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• pp.242-252
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• 2017

This paper deals with the blocking of DC-fault current during DC cable short-circuit conditions in HVDC (High-Voltage DC) transmission systems utilizing Modular Multilevel Converters (MMCs), where a new SubModule (SM) topology circuit for the MMC is proposed. In this SM circuit, an additional Insulated-Gate Bipolar Translator (IGBT) is required to be connected at the output terminal of a conventional SM with a half-bridge structure, hereafter referred to as HBSM, where the anti-parallel diodes of additional IGBTs are used to block current from the grid to the DC-link side. Compared with the existing MMCs based on full-bridge (FB) SMs, the hybrid topologies of HBSM and FBSM, and the clamp-double SMs, the proposed topology offers a lower cost and lower power loss while the fault current blocking capability in the DC short-circuit conditions is still provided. The effectiveness of the proposed topology has been validated by simulation results obtained from a 300-kV 300-MW HVDC transmission system and experimental results from a down-scaled HVDC system in the laboratory.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.529-532
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• 2002

본 과제를 통해 금속 구조물 음극 방식용 고성능 스위칭 정류기를 개발하였다. 개발된 정류기 회로는 크게 두 부분, 즉 1대로 구성된 AC/DC 컨버터부와 4대로 구성된 Module Type DC/DC 컨버터부로 되어 있다. AC/DC 컨버터는 IGBT PWM Rectifier로서 입력전압의 역률을 거의 1로 제어하고 있으며 또한 DC Link 전압을 일정하게 제어하고 있다. Module Type DC/DC 컨버터는 ZCS/ZVS 스위칭 동작을 통하여 스위칭 손실 감소와 함께 고주파 동작을 가능하게 하여, 입력측과 출력측의 전기적 절연을 위한 변압기로 고주파 변압기를 사용할 수 있게 하였다. 이로 인해 시스템의 부피와 무게를 현저히 감소시켰다. 본 과제에서 개발한 방식용 정류기 기술은 다른 유사 분야에의 적용도 가능한 것으로 사료된다.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.550-559
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• 2005

The matrix converter provides sinusoidal input and output wave forms, bidirectional power flow, controllable input power factor and a long life, compared to the VSI(Voltage Source Inverter) with diode rectification stage at the input. However it has tasks, such as complexity of the control method, ride-through problem and low voltage-ratio limitation, to overcome for commercializing, This paper describes the design, construction and implementation of matrix converter based on space vector modulation technique. The implemented prototype of matrix converter is built using the exclusive IGBT module and control circuit constituted with DSP and CPLD and it has an input filter, overvoltage protection circuit and commutation means for overcoming practical issues. The good results tested using an induction motor are also presented.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1211-1214
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• 1992

AC servo motor drives, Fara DS series, proposed in this paper can be effectively used in robots, CNC machine tools, and FA system with AC servo motors as actuators. The inverter of the AC servo drive consists of IGBT (Insulated Gate Bipolar Transistor) which have high switching frequency. Noises and vibrations generated in variable speed control of AC servo motors can be greatly reduced due to their high switching frequencies. In the developed servo drive, maximum torque is always generated in the whole speed range by compensating phase shift, which results from the nonlinearies of the AC servo motor during abrupt acceleration and deceleration. Abundant protection functions are provided to prevent abnormal state of the servo motor, and furthermore diverse user options are considered provided for the effective application. The proposed AC servo motor drive is designed to minimize velocity variation with respect to external load, supply voltage, environmental temperature, and humidity, so can be widely used in the fields of factory automation including robots and CNC msachine tools.