• Title/Summary/Keyword: Primary windings

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Design and Fabrication of 1 MVA Single Phase HTS Transformer for Power Distribution with Natural Convection Cooling System

  • Kim, W. S.;Kim, S. H.;Park, K. D.;H. G. Joo;G. W. Hong;J. H. Han;Park, J. H.;H. S. Son;S. Y. Hahn
    • Progress in Superconductivity
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    • v.5 no.2
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    • pp.149-152
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    • 2004
  • The design and the fabrication of a 1 MVA single-phase HTS transformer are presented in this paper, The rated voltages are 22.9 ㎸ for primary and 6.6 ㎸ for secondary, and the rated currents are 44 A and 152 A respectively. The transformer has HTS double pancake type windings. This type of winding has many advantages such as ease of fabrication and maintenance, good distribution of surge voltage and insulation of windings. Single HTS wire was used for primary winding and four HTS parallel wires were used for secondary winding. These windings are arranged reciprocally with the shell type iron core. An FRP cryostat with room temperature bore was fabricated to isolate the iron core from the coolant. The winding will be cooled down to 65 K with sub-cooled liquid nitrogen using a GM-cryocooler. The sub-cooled liquid nitrogen has advantages of good insulation because of no bubbles as well as increased current capacity of HTS wire.

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Half-Bridge Zero Voltage Switching Converter with Three Resonant Tanks

  • Lin, Bor-Ren;Lin, Wei-Jie
    • Journal of Power Electronics
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    • v.14 no.5
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    • pp.882-889
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    • 2014
  • This paper presents a zero voltage switching (ZVS) converter with three resonant tanks. The main advantages of the proposed converter are its ability to reduce the switching losses on the power semiconductors, decrease the current stress of the passive components at the primary side, and reduce the transformer secondary windings. Three resonant converters with the same power switches are adopted at the low voltage side to reduce the current rating on the transformer windings. Using a series-connection of the transformer secondary windings, the primary side currents of the three resonant circuits are balanced to share the load power. As a result, the size of both the transformer core and the bobbin are reduced. Based on the circuit characteristics of the resonant converter, the power switches are turned on at ZVS. The rectifier diodes can be turned off at zero current switching (ZCS) if the switching frequency is less than the series resonant frequency. Therefore, the reverse recovery losses on the rectifier diodes are overcome. Experiments with a 1.6kW prototype are presented to verify the effectiveness of the proposed converter.

Coreless PCB transformer in HB ZVS DC/DC converter for vehicle FPL lamp power circuit (Coreless PCB 변압기를 이용한 자동차 전원 구동 FPL 램프 전원 회로)

  • Lee Wan-Yun;Chung Gyo-Bum
    • Proceedings of the KIPE Conference
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    • 2002.07a
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    • pp.253-256
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    • 2002
  • This paper proposes the application of coreless PCB transformer to Half-Bridge (HB), Zero-voltage-Switched (ZVS) DC/DC converter for FPL lamp with electronic ballast in vehicle. The designed 5 coreless PCB transformers for ballast driving voltage are parallel-connected in primary windings and series-connected in secondary windings. Coreless PCB transformer is designed to have spiral winding in order to transfer higher energy. The computer simulations of the proposed power circuit show coreless PCB transformer to have good performance.

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Design of 1 MVA Single Phase HTS Transformer with Pancake Windings Cooled by Natural Convection of Sub-cooled Liquid Nitrogen

  • Kim, Woo-Seok;Kim, Sung-Hoon;Hahn, Song-yop;Park, Kyeong-Dal;Joo, Hyeong-Gil;Hong, Gye-Won;Han, Jin-Ho;Lee, Don-Kun;Park, Yeon-Suk
    • Progress in Superconductivity and Cryogenics
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    • v.5 no.3
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    • pp.34-37
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    • 2003
  • A 1 MVA single-phase high temperature superconducting (HTS) transformer with BSCCO-2223 wire was designed in this paper. The rated voltages of each sides of the transformer are 22.9 kV and 6.6 kV respectively. Double pancake HTS windings arranged reciprocally will be used for the transformer windings, because of the advantages of insulation and distribution of surge voltage in case of a large power and high voltage transformer. Single HTS wire was used for the primary windings and four parallel wires were used for the secondary windings of the transformer with transposition. A core of the transformer was designed as a shell type core separated with the windings by a cryostat made of GFRP with a room temperature bore. The operating temperature of the HTS windings will be about 65K with sub-cooled liquid nitrogen. A cryogenic cooling system using a GM-cryocooler for this HTS transformer by natural convection of liquid nitrogen was designed. This type of cooling system can be a good option for compactness, efficiency, and reliability of the HTS transformer.

Design and Fabricate a 1 MVA Single Phase HTS Transformer with Four Parallel Pancake Windings (4병렬 팬케이크 권선을 사용한 1 MVA 단상 고온초전도 변압기의 설계 및 제작)

  • Kim, Woo-Seok;Kim, Sung-Hooon;Lee, Sang-Jin;Choi, Kyeong-Dai;Joo, Hyeong-Gil;Hong, Gye-Won;Han, Jin-Ho;Hahn, Song-Yop;Park, Jung-Ho;Song, Hee-Suck
    • Proceedings of the KIEE Conference
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    • 2003.07b
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    • pp.723-725
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    • 2003
  • The result of design and Partial fabrication of a 1 MVA single phase high temperature superconducting(HTS) transformer for power distributions are presented in this paper. The HTS windings are wound as double pancake windings which have advantages of uniform distribution of high voltage over the windings. the rated primary and secondary voltages are 22.9 kV and 6.6 kV respectively. Four HTS tapes are wound in parallel for secondary windings considering the rated currents of the transformer. The HTS windings will be cooled down to 65 K by natural convection of sub-cooled liquid nitrogen using a single-staged GM-cryocooler in order to make the stability of the HTS windings better. The iron core is designed as shell type and isolated from the liquid nitrogen by an FRP cryostat which have a room temperature bore. After the complete fabrication of the total HTS transformer system, performance test of the transformer will be carried out.

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Cell Balancing Scheme with Series Coupling of Multiple Primary Windings for Hybrid Electric Vehicle Lithium-Ion Battery Cells

  • Park, Hong-Sun;Kim, Chong-Eun;Moon, Gun-Woo;Lee, Joong-Hui
    • Proceedings of the KIPE Conference
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    • 2007.07a
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    • pp.347-349
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    • 2007
  • Charge equalization scheme for HEV lithium-ion battery system is proposed in this paper, where all the primary windings with in parallel bi-directional switches are coupled in series to provide the equalizing energy from the whole battery string to the specific under charged cells. Moreover, to realize minimized size of equalization circuit employing the proposed cell balancing scheme, the optimal power rating design rule according to equalization time and SOC distribution of imbalance is proposed. A prototype of HEV lithium-ion battery system of four cells shows the outstanding charge equalization performance while maintaining greatly reduced size of cell balancing circuit.

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Current Limiting Characteristics of transformer type SFCL using neutral line (중성점을 이용한 변압기형 초전도 한류기의 전류제한 특성 분석)

  • Cho, Yong-Sun;Choi, Hyo-Sang;Park, Hyoung-Min;Lee, Ju-Hyoung;Jung, Byung-Ik
    • Proceedings of the KIEE Conference
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    • 2007.07a
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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.

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Analysis of Voltage Stress in Stator Windings of IGBT PWM Inverter-Fed Induction Motor Systems

  • Hwang Don-Ha;Lee Ki-Chang;Jeon Jeong-Woo;Kim Yong-Joo;Lee In-Woo;Kim Dong-Hee
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.1
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    • pp.43-49
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    • 2005
  • The high rate of voltage rise (dv/dt) in motor terminals caused by high-frequency switching and impedance mismatches between inverter and motor are known as the primary causes of irregular voltage distributions and insulation breakdowns on stator windings in IGBT PWM inverter-driven induction motors. In this paper, voltage distributions in the stator windings of an induction motor driven by an IGBT PWM inverter are studied. To analyze the irregular voltages of stator windings, high frequency parameters are derived from the finite element (FE) analysis of stator slots. An equivalent circuit composed of distributed capacitances, inductance, and resistance is derived from these parameters. This equivalent circuit is then used for simulation in order to predict the voltage distributions among the turns and coils. The effects of various rising times in motor terminal voltages and cable lengths on the stator voltage distribution are also presented. For a comparison with simulations, an induction motor with taps in the stator turns was made and driven by a variable-rising time switching surge generator. The test results are shown.

Characteristics of Hybrid-Type SFCL by the Number of Secondary Windings with YBCO Films (2차회로의 수에 따른 하이브리드형 초전도 한류기의 동작 특성)

  • Cho Yong-Sun;Choi Hyo-Sang;Park Hyoung-Min
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.55 no.2
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    • pp.62-66
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    • 2006
  • We investigated the characteristics of the hybrid-type superconducting fault current limiter (SFCL) by the number of secondary windings. The SFCL consists of a transformer, which has a primary winding and several secondary windings with serially connected $YB_{a2}Cu_{3}O_{7}$ films. In order to increase the capacity. of the SFCL, the serial connection between each current limiting unit is necessary. Resistive-type SFCL has a difficulty in quenching simultaneously between the units due to slight differences of their critical current densities. The hybrid-type SFCL could achieve the simultaneous quenching through the electrical isolation and the mutual flux linkage among the units. We confirmed that the capacity of the SFCL could be increased effectively through the simultaneous quenching among the units. In addition, the power burden of the system could be reduced by adjusting the number of secondary windings. We will investigate the method to increase the capacity through serial and Parallel connections among current limiting units.

A study on an optimal design of the high frequency transformer in LLC DC to DC resonant converter (LLC DC to DC 공진 컨버터의 고주파 변압기 최적화 설계에 관한 연구)

  • Jong-Hae Kim
    • Journal of IKEEE
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    • v.27 no.4
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    • pp.587-600
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    • 2023
  • This paper presents an optimal design of the slim type high frequency transformer used in the LLC DC to DC resonant converter for 65-inch UHD-TV with the rated power of 315W. This paper also performs an optimal design of the slim type high frequency through core loss analysis, AC winding loss analysis, and optimization design of the winding arrangement of the LLC resonant transformer. Particularly, the high-efficiency and slim type high frequency transformer based on the obtained results from theoretical analysis in this paper is constructed in the interleaved and vertical winding structures of its transformer to realize the winding method of automatic type and minimize AC winding loss. The primary and secondary windings of the slim type high frequency transformer the vertical winding structure proposed in this paper used the Litz-wire windings, PCB and copper plate windings, respectively. Finally, an optimal design of the slim type high frequency transformer proposed in this paper was carried out through the experimental results to confirm the validity of theoretical analysis based on the simulation results using Maxwell 2D and 3D tool.