The Experts below are selected from a list of 6072 Experts worldwide ranked by ideXlab platform

Gun-woo Moon - One of the best experts on this subject based on the ideXlab platform.

  • High-Efficiency Slim Adapter With Low-Profile Transformer Structure
    IEEE Transactions on Industrial Electronics, 2012
    Co-Authors: Gun-woo Moon
    Abstract:

    This paper presents the implementation of a high-efficiency slim adapter using an resonant converter. A new structure of the slim-type transformer is proposed, which is composed of copper wire as the primary Winding and printed-circuit-board Winding on the outer layer as the Secondary Winding. The proposed structure is suitable for a slim and high-efficiency converter because it has advantages of easy utilization and wide conductive cross-sectional area. In addition, the voltage-doubler rectifier is applied to the Secondary side due to its simple structure of Secondary Winding, and a filter is adopted to reduce the output filter size. The validity of this study is confirmed by the experimental results from an 85-W prototype.

  • High efficiency slim adapter with low profile transformer structure
    8th International Conference on Power Electronics - ECCE Asia, 2011
    Co-Authors: Gun-woo Moon
    Abstract:

    This paper presents the implementation of high efficiency slim adapter using LLC resonant converter. A new structure of slim-type transformer is proposed, which is composed of copper wire as primary Winding and printed circuit-board(PCB)-Winding on the outer layer as Secondary Winding. The proposed structure is suitable for slim and high efficiency converter because it has advantages of easy utilization and wide conductive cross-sectional area. In addition, the voltage-doubler rectifier is applied to the Secondary side due to its simple structure of Secondary Winding and CLC filter is adopted to reduce output filter size. The validity of this study is confirmed by the experimental results from an 85W prototype.

Tang Dahai - One of the best experts on this subject based on the ideXlab platform.

  • d side current phase compensation method for ynd5 transformer longitudinal differential protection
    2015
    Co-Authors: Liu Congzhou, Tang Dahai, Wang Ji, Wang Yucheng, Yang Lei
    Abstract:

    The invention discloses a d-side current phase compensation method for YNd5 transformer longitudinal differential protection. The method is characterized by connecting the high-voltage side TA Secondary Winding and the low-voltage side TA Secondary Winding of an YNd5 transformer both in a star connection manner and performing current phase compensation on the d side of the YNd5 transformer. The method has beneficial effects of being a current phase software compensation technology scheme suitable for transformer longitudinal differential protection devices with various voltage classes for YNd5 wiring in a power transmission and distribution network power station, being simple and clear, and being easy to implement.

  • ynd7 wiring transformer longitudinal differential protection current phase compensation method
    2014
    Co-Authors: Tang Dahai, Cao Haiou, Cao Bin
    Abstract:

    The invention belongs to relay protection control technologies of a power transmission and distribution network, and relates to a YNd9 transformer longitudinal differential protection current phase compensation method. According to the YNd9 transformer longitudinal differential protection current phase compensation method, a YNd9 wiring transformer d-side c-phase TA Secondary Winding current is connected to an a-phase current loop of a YNd11 wiring computerized transformer differential protection d side; a YNd9 wiring transformer d-side b-phase TA Secondary Winding current is connected to a b-phase current loop of the YNd11 wiring computerized transformer differential protection d side; a YNd9 wiring transformer d-side a-phase TA Secondary Winding current is connected with a c-phase current loop of the YNd11 wiring computerized transformer differential protection d side; phase compensation is carried out on YNd9 wiring transformer differential protection through software phase compensation of a YNd11 wiring computerized transformer differential protection device. According to the YNd9 transformer longitudinal differential protection current phase compensation method, current phase compensation for YNd9 wiring transformer differential protection can be completed, and the method is simple in principle and convenient to implement.

  • longitudinal differential protection current phase compensation method for ynd11 wiring transformer
    2013
    Co-Authors: Tang Dahai, Yi Xin, Ma Haiwei, Qi Ming
    Abstract:

    The invention relates to a longitudinal differential protection current phase compensation method for an YNd series transformer. The method is that TA Secondary Winding of the high-voltage side and TA Secondary Winding of the low-voltage side of the YNd series transformer are respectively connected through star connection, A phase current, B phase current and C phase current of the TA Secondary Winding of the Y side of the YNd series transformer are respectively switched in an A phase current loop, a B phase current loop and a C phase current loop of YNd11 or YNd1 transformer differential protection, and phase current of the TA Secondary Winding of the d side of the transformer is correspondingly switched in a phase current loop of the d side of an YNd11 or YNd1 wiring microcomputer transformer differential protection device when certain phase current of the d side of the transformer is the same as a certain phase current phase of the d side of a YNd11 or YNd1 transformer. The method is simple in principle and convenient to implement, completely conforms to a transformer differential protection current phase compensation principle, and can adapt to unusual YNd series transformer longitudinal differential protection current phase compensation of the transformers of various voltage levels.

G. Maggetto - One of the best experts on this subject based on the ideXlab platform.

  • Control of a three-phase PWM rectifier using estimated AC-side and DC-side voltages
    IEEE Transactions on Power Electronics, 1999
    Co-Authors: T. Ohnuki, O. Miyashita, P. Lataire, G. Maggetto
    Abstract:

    A new control method of a pulsewidth modulation (PWM) rectifier without measuring AC- and DC-side voltages is proposed. As information about these voltages is necessary for the controller, all required voltage values are estimated from the measured line currents and the calculated values of the input reactor voltage during switching of the rectifier circuit. The input reactor voltage can be obtained by using a differentiator that produces the derivative of the line current or by detecting the voltage induced in a Secondary Winding wound on the input reactor. The Secondary Winding creates the electric isolation between the main circuit and the controller. The proposed method is verified by experiment. This paper describes the estimation method, gives the configuration of the controller, and discusses steady-state and transient performances of the rectifier.

Yu Zhang - One of the best experts on this subject based on the ideXlab platform.

  • The Dynamic and Optimized Modeling Method of Secondary Winding for Transformer
    IOP Conference Series: Materials Science and Engineering, 2017
    Co-Authors: Xiudong Xu, Liang Zhao, Rui Li, Bo Zeng, Jie Cheng, Zhiyuan Shen, Yu Zhang
    Abstract:

    In order to analyze dynamic characteristics of Secondary Winding for Transformer, one joint interface dynamic modeling and optimized methodology is provided in this paper. A layer of equivalent material between Secondary Winding and clamp is established, which can simulate stiffness and damp in the joint interface. The initial elastic modulus, poisson ratio and density of equivalent material are deduced from Hertz contact theory and fractal theory. The final property parameters of equivalent material are obtained by using optimized model. Simulation and experiments results show that the dynamic and optimized model can simulate experimental results exactly. The relative errors between the simulation frequencies of new model and experimental frequencies are controlled within 2%.

  • a compact multi wire layered Secondary Winding for tesla transformer
    Review of Scientific Instruments, 2017
    Co-Authors: Liang Zhao, Jiancang Su, Rui Li, Xiaolong Wu, Xiudong Xu, Bo Zeng, Jie Cheng, Yu Zhang
    Abstract:

    A compact multi-wire-layered (MWL) Secondary Winding for a Tesla transformer is put forward. The basic principle of this Winding is to wind the metal wire on a polymeric base tube in a multi-layer manner. The tube is tapered and has high electrical strength and high mechanical strength. Concentric-circle grooves perpendicular to the axis of the tube are carved on the surface of the tube to wind the wire. The width of the groove is basically equal to the diameter of the wire so that the metal wire can be fixed in the groove without glue. The depth of the groove is n times of the diameter of the wire to realize the n-layer Winding manner. All the concentric-circle grooves are connected via a spiral groove on the surface of the tube to let the wire go through. Compared with the traditional one-wire-layered (OWL) Secondary Winding for the Tesla transformer, the most conspicuous advantage of the MWL Secondary Winding is that the latter is compact with only a length of 2/n of the OWL. In addition, the MWL Winding has the following advantages: high electrical strength since voids are precluded from the surface of the Winding, high mechanical strength because polymer is used as the material of the base tube, and reliable fixation in the Tesla transformer as special mechanical connections are designed. A 2000-turn MWL Secondary Winding is fabricated with a Winding layer of 3 and a total length of 1.0 m. Experiments to test the performance of this Winding on a Tesla-type pulse generator are conducted. The results show that this Winding can boost the voltage to 1 MV at a repetition rate of 50 Hz reliably for a lifetime longer than 104 pulses, which proves the feasibility of the MWL Secondary Winding.

  • a compact multi wire layered Secondary Winding for tesla transformer
    Review of Scientific Instruments, 2017
    Co-Authors: Liang Zhao, Jiancang Su, Rui Li, Xiaolong Wu, Xiudong Xu, Bo Zeng, Jie Cheng, Yu Zhang
    Abstract:

    A compact multi-wire-layered (MWL) Secondary Winding for a Tesla transformer is put forward. The basic principle of this Winding is to wind the metal wire on a polymeric base tube in a multi-layer manner. The tube is tapered and has high electrical strength and high mechanical strength. Concentric-circle grooves perpendicular to the axis of the tube are carved on the surface of the tube to wind the wire. The width of the groove is basically equal to the diameter of the wire so that the metal wire can be fixed in the groove without glue. The depth of the groove is n times of the diameter of the wire to realize the n-layer Winding manner. All the concentric-circle grooves are connected via a spiral groove on the surface of the tube to let the wire go through. Compared with the traditional one-wire-layered (OWL) Secondary Winding for the Tesla transformer, the most conspicuous advantage of the MWL Secondary Winding is that the latter is compact with only a length of 2/n of the OWL. In addition, the MWL windi...

  • analysis on turn to turn insulation of the Secondary Winding in tesla transformer
    International Conference on Condition Monitoring and Diagnosis, 2016
    Co-Authors: Liang Zhao, Rui Li, Bo Zeng, Jie Cheng, Yu Zhang, J C Su, L Zheng, B X Yu, X L Wu
    Abstract:

    A criterion to describe the turn-to-turn discharge of the Secondary Winding in Tesla transformers is presented. Factors which have influences on the turn-to-turn insulation of the Winding such as the wire diameter, the wire distance, the void size, the purity of transformer oil and the insulation strength of the wire are researched based on this criterion. By theoretical calculation, the electric field enhancement factor (FEF) dependent on the wire diameter and the wire distance is presented. It is found that an optimum ratio of the wire diameter to the wire distance exists which corresponds to the minimum FEF. Via the Paschen's Curve, the electric breakdown strength (E b ) for voids with different sizes is deduced, and it is found that the existence of voids makes the discharge occur more easily due to void's lower E b but if the size of a void is smaller than a certain value, it cannot affect the Winding's turn-to-turn insulation. Through experiments, E b of the traditional enamel wire and that of the three-layered insulation (TLI) wire are compared. The results show that E b of the three-layered wire is basically two times of that of an enamel wire. Based on the results, suggestions to improve the insulation of the Secondary Winding in Tesla transformers are summarized.

  • static voltage distribution between turns of Secondary Winding of air core spiral strip transformer and its application
    Review of Scientific Instruments, 2011
    Co-Authors: Hongbo Zhang, Xinbing Cheng, Yu Zhang
    Abstract:

    The static voltage distribution between Winding turns has great impact on output characteristics and lifetime of the air-core spiral strip pulse transformer (ACSSPT). In this paper, Winding inductance was calculated by electromagnetic theory, so that the static voltage distribution between turns of Secondary Winding of ACSSPT was analyzed conveniently. According to theoretical analysis, a voltage gradient because of the turn-to-turn capacitance was clearly noticeable across the ground turns. Simulation results of Pspice and CST EM Studio codes showed that the voltage distribution between turns of Secondary Winding had linear increments from the output turn to the ground turn. In experiment, the difference in increased voltage between the ground turns and the output turns of a 20-turns Secondary Winding is almost 50%, which is believed to be responsible for premature breakdown of the insulation, particularly between the ground turns. The experimental results demonstrated the theoretical analysis and simula...

Hyoungmin Park - One of the best experts on this subject based on the ideXlab platform.

  • characteristics of transformer type superconducting fault current limiter depending on reclosing in changing the number of turns of Secondary Winding
    Physica C-superconductivity and Its Applications, 2011
    Co-Authors: Soogeun Choi, Hyosang Choi, Hyoungmin Park, Byungik Jung, Kyounghun Ha
    Abstract:

    Abstract The amount of consumed power is increasing with industrial development and rapidly increasing population. In accidents due to increased power consumption, the fault current sharply increases. Superconducting fault current limiters (SFCL) are studied widely to limit such fault currents. In this study, the characteristics of a transformer-type SFCL are analyzed depending on reclosing in changing the number of Secondary Winding turns. For experiment conditions, the turn ratio of the primary and Secondary Windings of a transformer-type SFCL was set to 4:2 and 4:4. The voltage was incremented by 80 V from 120 V for the experiment. The circuit breaker was operated with two open times of CO-0.17 s – CO-0.17 s – CO seconds (C; closed, O; open), respectively. Comparing the result for the experiment conditions with the case of the turn ratios of the primary and Secondary Windings at 4:4 and 4:2, the fault current was limited effectively in 4:2 than in 4:4 for the fault current limit ratios. With respect to the result of recovery characteristics, it was examined that the superconducting unit recovered faster when the turn ratio of the primary and Secondary Windings was 4:2 than 4:4. Comparing the amount of consumed power related to the recovery characteristics of the superconducting element, it was examined that the recovery time was faster in less power consumption for the superconducting unit. As such, since a transformer-type SFCL depending on reclosing in changing the number of turns of the Secondary Winding controls the turn ratio of the Secondary Winding to control fault current limiting and recovery characteristics, it can normally operate.

  • Recovery Behaviors of the Transformer-Type SFCL With or Without Neutral Lines
    IEEE Transactions on Applied Superconductivity, 2009
    Co-Authors: Hyosang Choi, Hyoungmin Park
    Abstract:

    This study was to analyze the recovery characteristics for the superconducting element in the transformer-type superconducting fault current limiter (SFCL) consisted of iron core, elements in primary and Secondary Windings. The superconducting element was connected to the Secondary Windings of a transformer-type SFCL in series. In order to increase the power capacity of the SFCL, the number of the superconducting elements should be increased and the recovery time of each superconducting element should be also shortened. When the number of superconducting elements in Secondary Winding was increased, the recovery time of the superconducting elements according to the voltage increase in the transformer-type SFCL grew longer because of unbalanced quenching of the superconducting elements. However, as for the transformer-type SFCL that has neutral lines connected between the Secondary Winding and the superconducting elements, the recovery time grew shorter due to the enhancement of quenching behavior. The transformer-type SFCL with the neutral lines was more profitable for the capacity increase of the SFCL.