• 전력전자학회논문지
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• 제18권2호
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• pp.169-177
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• 2013

This paper proposes a new configuration of bidirectional intelligent semiconductor transformer with rating of 1.9kV/127V, 2kVA. The proposed transformer consists of high-voltage high-frequency AC-DC rectifier, and low-voltage DC-DC and DC-AC converters. The operational feasibility of proposed transformer was verified by computer simulation with PSCAD/EMTDC software. Based on the simulation results, a hardware prototype with rating of 1.9kV/127V, 2kVA was built and tested in the lab to confirm the feasibility of hardware implementation. Using three units of this transformer, a 3-phase transformer with rating of 3.3kV/220V, 6kVA can be built.

• 한국기계가공학회지
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• 제21권9호
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• pp.1-11
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• 2022

Recently, there has been continuous technological development in the semiconductor industry, and semiconductor manufacturing technologies are being advanced and highly integrated. For this reason, ceramic material having excellent heat resistance, wear resistance, and conductivity are used as components in semiconductor manufacturing. Among them, the probe card's space transformer is used as ceramic material to prevent electronic signal noise during the electrical die sorting of semiconductor function testing. However, implementing a bulk-type space transformer with a thickness of 5.6 mm or more is challenging, and thus it is produced in a structure with a stacked ceramic film. The stacked space transformer has low productivity because it is difficult to ensure hole clogging and a precise shape. In this research, an ultrasonic horn is designed to manufacture a bulk-type ceramic space transformer through ultrasonic drilling. Vibration characteristics were analyzed according to the ultrasonic horn, and the natural frequency was measured.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.95-100
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• 2022

In this paper, a power loss analysis technique of a high-frequency transformer of a bidirectional DAB (Dual Active Bridge) converter is reported. To miniaturize the transformer of the dual active bridge converter, a resonant inductor was designed with an air gap included low-coupled rate state core to combine leakage inductor with the resonant inductor which is required for soft-switching. In this paper, leakage inductance and magnetizing inductance, core material, type of winding and winding method are included in the dual active bridge transformer loss analysis process to enable optimal design at the initial design stage. Transformer loss analysis for dual active bridge with a switching frequency of 200 kHz and maximum output of 5 kW was executed, and elements necessary for design based on the number of turns on the primary side were graphed while maintaining the transformer turns ratio and window area. In particular, it was possible to determine the optimal number of turns and thickness of the transformer, and ultimately, the total loss of the transformer could be estimated.

• 반도체공학회 논문지
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• 제1권1호
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• pp.23-30
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• 2023

최근 거대 IT 기업들의 Generative AI 기술 개발로 Transformer 모델의 규모가 조 단위를 넘어가며 기하급수적으로 증가하고 있다. 이러한 AI 서비스를 지속적으로 가능케 하기 위해선 모델 경량화가 필수적이다. 본 논문에서는 하드웨어 친화적으로 구조화된(structured) 프루닝 패턴을 찾아 Transformer 모델의 경량화 방법을 제안한다. 이는 모델 알고리즘의 특성을 살려 압축을 진행하기 때문에 모델의 크기는 줄어들면서 성능은 최대한 유지할 수 있다. 실험에 따르면 GPT2 와 BERT 언어 모델을 프루닝할 때 제안하는 구조화된 프루닝 기법은 희소성이 높은 영역에서도 미세 조정된(fine-grained) 프루닝과 거의 흡사한 성능을 보여준다. 이 접근 방식은 미세 조정된 프루닝 대비 0.003%의 정확도 손실로 모델매개 변수를 80% 줄이고 구조화된 형태로 하드웨어 가속화를 진행할 수 있다.

• 한국인터넷방송통신학회논문지
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• 제15권1호
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• pp.253-259
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• 2015

우리는 이 논문에서 교류전압원의 극성에 따라서 쌍방향으로 동작하는 반도체 변압기설계를 제시한다. 변압기는 회로 사이의 유도성 결합에 의하여 에너지를 전달하는 장치이다. 대부분의 변압기는 교류 전압에 의하여 1차 및 2차 코일로 구성된 장치이다. 우리가 제시하는 시스템은 전압신호 레벨을 두 방향으로 즉, 전원에서 부하까지 전압신호가 전달되기도 하고, 부하에서 전압원까지 전달되기도 한다. 전환하는 하나의 회로로 설계되어있다. 구성한 반도체 스위치는 NPN 트랜지스터가 교류 전압원 단자에 연결되어 있고, 에너지 저장 요소로서는 이미터 단자에 연결되어 있는 인덕터를 채택하였다. 제어 신호는 반도체의 베이스 단자에 인가된다. 제시하는 시스템은 전압신호의 진폭을 가역 방향으로 변화시킬 수 있다.

• 한국인터넷방송통신학회논문지
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• 제22권4호
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• pp.127-132
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• 2022

철도차량에 탑재된 전장품 중 가장 큰 하중을 차지하는 것은 주변압기로 낮은 운전 주파수(60Hz)로 인해 전력밀도가 0.2~0.4 MVA/ton 정도로 낮아 경량화에 중요한 요소로 작용하고 있다. 따라서 철도차량용 주변압기를 개선하기 위해 몰드 변압기, 반도체 변압기 등에 관한 연구가 국내외적으로 활발히 진행 중이다. 한편 국내외 철도차량에 대부분 적용되는 견인전동기로 최근에는 유도전동기를 대체하여 영구자석 동기전동기(PMSM)를 적용하려는 시도가 이루어지고 있다. 영구자석 동기전동기(PMSM)는 유도전동기에 비해 높은 출력밀도와 효율 확보가 가능하지만 제작에 필요한 재료의 가격이 비싸고 설계가 유도전동기 대비 다소 어렵다는 단점이 있다. 이러한 문제점을 고려하여 본 논문에서는 소형 경량화가 가능한 반도체 변압기를 적용하고, 철도차량의 경량화, 고효율화 등의 요구사항에 맞춰 구조가 간단하면서 회전수가 높고 고토크, 저비용인 SRM을 적용할 수 있는 연구내용을 제안하고자 한다.

• 반도체디스플레이기술학회지
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• 제6권2호
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• pp.29-33
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• 2007

Low frequency (400 kHz) Ferrite ICP has been proposed for large area processing. Because the coupling coefficient is close to 1, the transformer matching can be adapted to Ferrite ICP. The transformer matching system is simple. In this paper the new matching system by controlling the turns of transformer using relays is proposed for impedance matching. We developed a simple matching system and characterized it when the turns were changed. It was observed that the 2-channel relay is available for transformer matching.

• 전력전자학회논문지
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• 제25권6호
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• pp.496-502
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• 2020

The reliability of a solid-state transformer (SST) is one of the important aspects to consider when replacing a conventional low-frequency passive transformer with SST for urban railway vehicles. Lifetime evaluation of SST in the design phase is therefore essential in guaranteeing a certain SST reliability. In this study, a lifetime evaluation of power semiconductor devices in SST is performed with respect to temperature stress. For a case study, a 3 MW SST with three kinds of power modules (one IGBT module and two SiC-MOSFET modules) is used for the lifetime estimation under the operation profile of urban railway vehicles.

• 전기학회논문지
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• 제62권12호
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• pp.1678-1687
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• 2013

This paper describes a prototype of 3-phase 3.3kV/220V 6kVA modular semiconductor transformer developed in the lab for feasibility study. The developed prototype is composed of three single-phase units coupled in Y-connection. Each single-phase unit with a rating of 1.9kV/127V 2kVA consists of a high-voltage high-frequency resonant AC-DC converter, a low-voltage hybrid-switching DC-DC converter, and a low-voltage hybrid-switching DC-AC converter. Also each single-phase unit has two DSP controllers to control converter operation and to acquire monitoring data. Monitoring system was developed based on LabView by using CAN communication link between the DSP controller and PC. Through various experimental analyses it was verified that the prototype operates with proper performance under normal and sag condition. The system efficiency can be improved by adopting optimal design and replacing the IGBT switch with the SiC MOSFET switch. The developed prototype confirms a possibility to build a commercial high-voltage high-power semiconductor transformer by increasing the number of series-connected converter modules in high-voltage side and improving the performance of switching element.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.291-293
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• 2003

A semiconductor switch-based fast hi-polar high voltage pulse generator is proposed in this paper The proposed pulse system is made of a thyristor based-rectifier, DC link capacitor, a push-pull resonant inverter, a high voltage transformer. secondary capacitor, a high voltage IGBT & diode stacks, and a variable capacitor. The proposed system makes hi-polar high voltage sinusoidal waveform using resonance between leakage inductance of the transformer and secondary capacitor and transfers energy to output load at maximum of the secondary capacitor voltage. Compared to previous hi-polar high voltage pulse power supply using nonlinear transmission line, the proposed pulse power system using only semiconductor switches has simple structure and gives high efficiency