• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.2
• /
• pp.169-177
• /
• 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.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.9
• /
• pp.1-11
• /
• 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.

• Journal of the Semiconductor & Display Technology
• /
• v.21 no.2
• /
• pp.95-100
• /
• 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.

• Transactions on Semiconductor Engineering
• /
• v.1 no.1
• /
• pp.23-30
• /
• 2023

With the recent development of Generative AI technology by IT giants, the size of the transformer model is increasing exponentially over trillion won. In order to continuously enable these AI services, it is essential to reduce the weight of the model. In this paper, we find a hardware-friendly structured pruning pattern and propose a lightweight method of the transformer model. Since compression proceeds by utilizing the characteristics of the model algorithm, the size of the model can be reduced and performance can be maintained as much as possible. Experiments show that the structured pruning proposed when pruning GPT-2 and BERT language models shows almost similar performance to fine-grained pruning even in highly sparse regions. This approach reduces model parameters by 80% and allows hardware acceleration in structured form with 0.003% accuracy loss compared to fine-tuned pruning.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.1
• /
• pp.253-259
• /
• 2015

In this paper, we propose a transformer of alternating voltage source utilizing a semiconductor, operating in bidirectional fashion. Transformer is a device transferring energy by inductive coupling between its winding circuits. Conventional transformer is a device, composed of a primary coil and a secondary coil, transforming an alternating voltage. The system we propose is designed with a single circuit transforming the level of voltage signal in two ways; from the source to the load, and vice versa. For semiconductor switches, the NPN transistor is connected to the alternating voltage source terminal, and emitter terminal is connected to the inductor in the system as an energy storage element. The control signal is applied to the base terminal of the semiconductors. We have shown that the system we propose, by adopting only one circuit, drives an alternating voltage transformer that changes the amplitudes of voltage signal in reciprocal way.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.4
• /
• pp.127-132
• /
• 2022

Among the electrical components mounted on railroad cars, the largest load is the main transformer, which has a low power density of 0.2~0.4 MVA/ton due to the low operating frequency(60Hz), which is an important factor for weight reduction. Therefore, research on molded transformers, semiconductor transformers, etc. is being actively conducted at Domestic and foreign in order to improve the main transformer for railway vehicles. Meanwhile, attempts are being made to apply a permanent magnet synchronous motor (PMSM) to replace an induction motor as a traction motor that is mostly applied to domestic and foreign railway vehicles. Permanent magnet synchronous motors (PMSMs) can secure higher power density and efficiency compared to induction motors, but have disadvantages in that the materials required for manufacturing are expensive and design is somewhat difficult compared to induction motors. Considering these problems, in this paper, we suggest that a small and lightweight semiconductor transformer is applied, and a simple structure, high torque, low cost SRM can be applied in accordance with the requirements such as weight reduction and high efficiency of railroad vehicles. content.

• Journal of the Semiconductor & Display Technology
• /
• v.6 no.2 s.19
• /
• pp.29-33
• /
• 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.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.6
• /
• pp.496-502
• /
• 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.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.12
• /
• pp.1678-1687
• /
• 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.

• Proceedings of the KIPE Conference
• /
• 2003.07a
• /
• pp.291-293
• /
• 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