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Hirotaka Koizumi - One of the best experts on this subject based on the ideXlab platform.

  • analysis of half wave class de low dv dt rectifier at any duty ratio
    IEEE Transactions on Power Electronics, 2014
    Co-Authors: Kazuaki Fukui, Hirotaka Koizumi
    Abstract:

    Class DE low dv/dt rectifiers realize high-frequency high-efficiency rectification and low-Diode Voltage stress which is no more than the output Voltage. Half-wave Class DE low dv/dt rectifier, which is one of the Class DE rectifiers, realizes the common ground between the input port and the output port. In this paper, the half-wave Class DE low dv/dt rectifier is analyzed for any Diode-ON-duty ratio. The equations of the waveforms, the input and output powers, the current and Voltage transfer functions, the current and Voltage stresses, the power-output capability, and the power conversion efficiencies are obtained. Moreover, the characteristics of the normalized output power, the normalized input resistance and capacitance, the current and Voltage transfer functions, and the power-output capability are clarified as functions of the Diode-ON-duty ratio. The performance has been confirmed with the circuit experiment and the simulation in steady state. In the experiment and the simulation, the characteristics of the output Voltage and the power conversion efficiency against the amplitude of the input current, the operating frequency and the load resistance have been obtained. The experimental results well agreed with the simulation results.

  • half wave class de low dv dt rectifier
    Asia Pacific Conference on Circuits and Systems, 2012
    Co-Authors: Kazuaki Fukui, Hirotaka Koizumi
    Abstract:

    Class DE low dv/dt rectifier can reduce the Diode switching losses with satisfying the peculiar switching conditions. Moreover, Class DE low dv / dt rectifier has the desirable characteristic of the low Diode Voltage stress which equals the output Voltage. As Class DE low dv / dt rectifier, some variants can be considered. In this paper, a half-wave Class DE low dv / dt rectifier when the Diode on duty ratio of each Diode equals 0.25 is analyzed in detail and experimented.

Kazuaki Fukui - One of the best experts on this subject based on the ideXlab platform.

  • analysis of half wave class de low dv dt rectifier at any duty ratio
    IEEE Transactions on Power Electronics, 2014
    Co-Authors: Kazuaki Fukui, Hirotaka Koizumi
    Abstract:

    Class DE low dv/dt rectifiers realize high-frequency high-efficiency rectification and low-Diode Voltage stress which is no more than the output Voltage. Half-wave Class DE low dv/dt rectifier, which is one of the Class DE rectifiers, realizes the common ground between the input port and the output port. In this paper, the half-wave Class DE low dv/dt rectifier is analyzed for any Diode-ON-duty ratio. The equations of the waveforms, the input and output powers, the current and Voltage transfer functions, the current and Voltage stresses, the power-output capability, and the power conversion efficiencies are obtained. Moreover, the characteristics of the normalized output power, the normalized input resistance and capacitance, the current and Voltage transfer functions, and the power-output capability are clarified as functions of the Diode-ON-duty ratio. The performance has been confirmed with the circuit experiment and the simulation in steady state. In the experiment and the simulation, the characteristics of the output Voltage and the power conversion efficiency against the amplitude of the input current, the operating frequency and the load resistance have been obtained. The experimental results well agreed with the simulation results.

  • half wave class de low dv dt rectifier
    Asia Pacific Conference on Circuits and Systems, 2012
    Co-Authors: Kazuaki Fukui, Hirotaka Koizumi
    Abstract:

    Class DE low dv/dt rectifier can reduce the Diode switching losses with satisfying the peculiar switching conditions. Moreover, Class DE low dv / dt rectifier has the desirable characteristic of the low Diode Voltage stress which equals the output Voltage. As Class DE low dv / dt rectifier, some variants can be considered. In this paper, a half-wave Class DE low dv / dt rectifier when the Diode on duty ratio of each Diode equals 0.25 is analyzed in detail and experimented.

Changhua Chen - One of the best experts on this subject based on the ideXlab platform.

  • effect of non uniform slow wave structure in a relativistic backward wave oscillator with a resonant reflector
    Physics of Plasmas, 2013
    Co-Authors: Changhua Chen, Renzhen Xiao, J Sun, Zhimin Song, Shaofei Huo, Xianchen Bai, Yanchao Shi, Guozhi Liu
    Abstract:

    This paper provides a fresh insight into the effect of non-uniform slow wave structure (SWS) used in a relativistic backward wave oscillator (RBWO) with a resonant reflector. Compared with the uniform SWS, the reflection coefficient of the non-uniform SWS is higher, leading to a lower modulating electric field in the resonant reflector and a larger distance to maximize the modulation current. Moreover, for both types of RBWOs, stronger standing-wave field takes place at the rear part of the SWS. In addition, besides Cerenkov effects, the energy conversion process in the RBWO strongly depends on transit time effects. Thus, the matching condition between the distributions of harmonic current and standing wave field provides a profound influence on the beam-wave interaction. In the non-uniform RBWO, the region with a stronger standing wave field corresponds to a higher fundamental harmonic current distribution. Particle-in-cell simulations show that with a Diode Voltage of 1.02 MV and beam current of 13.2 kA, a microwave power of 4 GW has been obtained, compared to that of 3 GW in the uniform RBWO.

  • a high efficiency overmoded klystron like relativistic backward wave oscillator with low guiding magnetic field
    Physics of Plasmas, 2012
    Co-Authors: Renzhen Xiao, J Sun, Weibing Tan, Zhimin Song, Changhua Chen
    Abstract:

    A klystron-like relativistic backward wave oscillator with a ratio of transverse dimension to free-space wavelength being about four is presented. In the beam-wave interaction region, the electron beam interacts with surface wave and volume wave simultaneously. The cathode holder plays an important role in the reflection of backward waves. A guard electrode, an electron collector ring, and a reflection ring are used to optimize the beam-wave interaction. The particle in cell simulation results reveal that microwaves with a power of 2 GW and a frequency of 12.3 GHz are generated with an efficiency of 42% when the Diode Voltage is 400 kV, the beam current 12 kA, and the magnetic field 0.48 T.

  • a high power high efficiency klystronlike relativistic backward wave oscillator with a dual cavity extractor
    Applied Physics Letters, 2011
    Co-Authors: Renzhen Xiao, Changhua Chen, Xiaowei Zhang, Lijun Zhang
    Abstract:

    A klystronlike relativistic backward wave oscillator (RBWO) with a dual-cavity extractor is presented. The phase of the axial electric field component E z varies by 0° in the dual-cavity extractor, and a larger electric field appears in the second extraction cavity, in comparison with a single-cavity extractor. Such an improved field distribution is beneficial for converting modulated beam power into microwave power. The particle in cell simulation results reveal that microwaves with power of 10 GW, frequency of 4.3 GHz are generated, and conversion efficiency is 48% when Diode Voltage is 1.2 MV and beam current 17.3 kA.

Huihuang Zhong - One of the best experts on this subject based on the ideXlab platform.

  • a dual mode operation overmoded coaxial millimeter wave generator with high power capacity and pure transverse electric and magnetic mode output
    Physics of Plasmas, 2016
    Co-Authors: Zhen Bai, Jun Zhang, Huihuang Zhong
    Abstract:

    An overmoded coaxial millimeter-wave generator with high power capacity and pure transverse electric and magnetic (TEM) mode output is designed and presented, by using a kind of coaxial slow wave structure (SWS) with large transversal dimension and small distance between inner and outer conductors. The generator works in dual-mode operation mechanism. The electron beam synchronously interacts with 7π/8 mode of quasi-TEM, at the meanwhile exchanges energy with 3π/8 mode of TM01. The existence of TM01 mode, which is traveling wave, not only increases the beam-wave interaction efficiency but also improves the extraction efficiency. The large transversal dimension of coaxial SWS makes its power capacity higher than that of other reported millimeter-wave devices and the small distance between inner and outer conductors allows only two azimuthally symmetric modes to coexist. The converter after the SWS guarantees the mode purity of output power. Particle-in-cell simulation shows that when the Diode Voltage is 400 kV and beam current is 3.8 kA, the generation of microwave at 32.26 GHz with an output power of 611 MW and a conversion efficiency of 40% is obtained. The power percentage carried by TEM mode reaches 99.7% in the output power.

  • a high efficient relativistic backward wave oscillator with coaxial nonuniform slow wave structure and depth tunable extractor
    Physics of Plasmas, 2013
    Co-Authors: Huihuang Zhong, Jun Zhang, Baoliang Qian
    Abstract:

    A high efficient relativistic backward wave oscillator with coaxial nonuniform slow-wave structures (SWSs) and depth-tunable extractor is presented. The physical mechanism to increase the power efficiency is investigated theoretically and experimentally. It is shown that the nonuniform SWSs, the guiding magnetic field distribution, and the coaxial extractor depth play key roles in the enhancement of the beam-wave power conversion efficiency. The experimental results show that a 1.609 GHz, 2.3 GW microwave can be generated when the Diode Voltage is 890 kV and the beam current is 7.7 kA. The corresponding power efficiency reaches 33.6%.

  • asymmetric mode competition in a relativistic backward wave oscillator with a coaxial slow wave structure
    Applied Physics Letters, 2010
    Co-Authors: Huihuang Zhong, Jun Zhang, Baoliang Qian, Lie Liu, Liang Gao, Chengwei Yuan
    Abstract:

    The initial experimental results of an L-band relativistic backward wave oscillator with a coaxial slow-wave structure are presented. The asymmetric-mode-competition mechanism in the device is investigated theoretically and experimentally. It is shown that the Diode Voltage, guiding-magnetic field, and concentricity play a key role in the suppression and excitation of the asymmetric-mode (coaxial quasi-TE11 mode). In the experiments, the asymmetric-mode with a frequency of 2.05 GHz is suppressed and excited, which is in good agreement with the theoretical results.

Sewan Choi - One of the best experts on this subject based on the ideXlab platform.

  • an improved current fed zvs isolated boost converter for fuel cell applications
    IEEE Transactions on Power Electronics, 2010
    Co-Authors: Hyung Joon Kim, Changwoo Yoon, Sewan Choi
    Abstract:

    This paper proposes an improved current-fed zero-Voltage switching isolated boost converter suitable for fuel cell applications. Preserving the inherent advantages of the current-fed converter which include smaller input current ripple, lower Diode Voltage rating, and lower transformer turns ratio, the proposed converter does not require any clamping and start-up circuits unlike the conventional current-fed converters. The Voltage ratings of the primary switches and secondary Diodes of the proposed converter are significantly reduced. Some alternative schemes of the proposed converter without the Voltage-second unbalance are presented. These characteristics of the proposed converter lead to a high overall efficiency over wider load range. Experimental results on a 1 kW prototype are provided to validate the proposed concept.

  • an improved current fed zvs isolated boost converter for fuel cell applications
    Applied Power Electronics Conference, 2008
    Co-Authors: Hyung Joon Kim, Changwoo Yoon, Sewan Choi
    Abstract:

    This paper proposes a novel current-fed ZVS isolated boost converter suitable for fuel cell applications. Preserving the advantages of the current-fed converter which include smaller input current ripple, lower Diode Voltage rating and lower transformer turns ratio, the proposed converter does not require any clamping and start-up circuits unlike the conventional current-fed converters. The Voltage ratings of the primary switches and secondary Diodes of the proposed converter are significantly reduced. The proposed converter can achieve ZVS at a lighter load condition with less leakage inductance. These characteristics of the proposed converter lead to a high overall efficiency over wider load range. Experimental results on a 1 kW prototype are provided to validate the proposed concept.