• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제4B권2호
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• pp.54-58
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• 2004

This paper presents the iron core design method of a high temperature superconducting (HTS) transformer considering voltages per turn (V/T). In this research, solenoid type HTS coils were selected for low voltage (LV) winding and double pancake coils for high voltage (HV) winding, just as in conventional large power transformers. V/T is one of the most fundamental elements used in designing transformers, as it decides the core cross sectional area and the number of primary and secondary winding turns. By controlling the V/T, the core dimension and core loss can be changed diversely. The leakage flux is another serious consideration in core design. The magnetic field perpendicular to the HTS wire causes its critical current to fall rapidly as the magnitude of the field increases slowly. Therefore in the design of iron core as well as superconducting windings, contemplation of leakage flux should be preceded. In this paper, the relationship between the V/T and core loss was observed and also, through computational calculations, the leakage magnetic fields perpendicular to the windings were found and their critical current decrement effects were considered in relation to the core design. The ％ impedance was calculated by way of the numerical method. Finally, various models were suggested.

• Journal of electromagnetic engineering and science
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• 제15권2호
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• pp.89-96
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• 2015

This paper describes the application of a passive noise cancellation method to a prototype inductor-inductor-capacitor (LLC) resonant converter by placing a compensation winding in a transformer to reduce common mode noise. The connection method for the compensation winding is investigated. A circuit analysis is implemented for the displacement currents between the primary and secondary windings in the transformer. The analyzed displacement currents are verified by performing a circuit simulation and a proper compensation winding connection that reduces common mode noise is found. The measurement results show that common mode noise is reduced effectively up to 20 dB in the 1 to 7 MHz frequency region for the prototype LLC resonant converter by using the proposed passive noise cancellation method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1130-1132
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• 2004

In this paper, we investigated the operational characteristics of the fault current limiting in the The flux-lock type high-Tc superconducting fault current limiter. The flux-lock type high-Tc superconducting fault current limiter was consisted of primary and secondary copper coils that flux was locked on iron core and YBCO thin film. The operational characteristic of a flux-lock type SFCL dependent on winding direction of coil 1 and coil 2, and the number of turns of coil 1 and coil 2, inductances of the coils, saturation in iron core, the properties of superconducting element etc. In this cases, we investigated the fault currents limiting characteristics of the flux-lock type SFCL when winding direction of coil 1 and coil 2 was subtractive polarity winding.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권2호
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• pp.65-72
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• 2001

This paper presents the design and test results of a 10kVA single phase HTS transformer which is operating at 77K. Double pancake windings with BSCCO -2223 HTS tape and GFRP cryostat with room temperature bore are used in the transformer. Four double pan cake windings were used in pancake windings are connected in parallel to conduct the secondary current of 45.4A. the rated voltages of each winding are 440/220V. Numerical calculation using Finite Element Method was used to evaluated the performance of each arrangement. Considering the magnetizing reactance, leakage reactance, electrical insulation and the circulating current in low voltage winding which had two windings in parallel, HLLH arrangement was finally chosen. Estimation of the AC loss, magnetizing loss and self field loss, in the design stage, where effects of perpendicular field and parallel field are considered. Room temperature bore type cryostat has been constructed and its heat loss was measured.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1610-1612
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• 2005

In this paper, the inductive power collector using electromagnetic induction for vehicle such as the PRT(Personal Rapid Transit) system is suggested and some ideas for power collector design to improve the power transfer performance are presented. The proposed the inductive power collector is used for the PRT system, which has a large air-gap and demands a large electrical power capability. But, low output power is generated due to a loosely coupled characteristic of the large air-gap. Therefore, double layer construction of secondary winding, which was divided in half to increase both output current and output voltage was suggested. Also, a model of power collector and parallel winding structure and a model of concentration/decentralization winding are presented, in addition, the performance of inductive power collector to alignment condition between the primary power line and the inductive power transformer was verified by computer simulation of 2kW model.

• 대한전기학회논문지:전력기술부문A
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• 제49권10호
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• pp.524-530
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• 2000

This paper presents a transformer protective relaying algorithm using the ratio of induced voltages. The proposed algorithm calculates primary and secondary voltage from currents and voltages of primary and secondary windings. The ratio of primary and secondary induced voltages is equal to the turn ratio in case of the steady state and magnetic inrush. On the other hand, the ratio is different form the turn ratio in case of internal winding faults. The algorithm does not require B-H curve and can reduce the relay's operating time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.926-927
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• 2008

This paper presents the ZVZCS(Zero- Voltage and Zero-Current-Switching) Full-Bridge converter using the secondary coupled inductor and auxiliary capacitor. The converter with phase-shift control is proposed to reduce the circulating loss in primary and the voltage stress in secondary side. Using a coupled winding of the output inductor, two auxiliary capacitors are generated to reset the primary current at circulating interval.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.161-164
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• 2009

This paper presents the ZVZCS(Zero Voltage and Zero-Current-Switching) Three-Level converter using the secondary coupled inductor and auxiliary capacitor. The converter with phase-shift control is proposed to reduce the circulating loss in primary and the voltage stress in secondary side. Using a coupled winding of the output inductor, two auxiliary capacitors are generated to reset the primary current at circulating interval.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.2090-2091
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• 2007

We investigated the characteristics of transformer type SFCL with neutral line. The transformer type SFCL having neutral line has achieved the simultaneous quench because the secondary winding has acted as parallel reactor. The fault current of SFCL was limited according to ratio of turn number between primary and secondary windings. Therefore, the power burden of superconducting element can be reduced by reduction of ratio of turn number between primary and secondary windings. As a result, we could expect reduction of it's volume in the transformer type SFCL.

• Journal of Magnetics
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• 제21권3호
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• pp.374-378
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• 2016

The transformer used in an inverter type arc welding machine is designed to use high frequency in order to reduce its size and cost. Also, selecting core materials that fit frequency is important because core loss increases in a high frequency band. An inrush current can occur in the primary coil of transformer during arc welding and this inrush current can cause IGBT, the switching element, to burn out. The transformer design was carried out in $A_P$ method and amorphous core was used to reduce the size of transformer. In addition, sheet coil was used for primary winding and secondary winding coil considering the skin effect. This paper designed the transformer core with an air gap to prevent IGBT burnout due to the inrush current during welding and proposed the optimum air gap length.