• Title, Summary, Keyword: Phase-shift method

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Current Sharing Method Based on Optimal Phase Shift Control for Interleaved Three-Phase Half Bridge LLC Converter with Floating Y-Connection

  • Shi, Lin;Liu, Bangyin;Duan, Shanxu
    • Journal of Power Electronics
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    • v.19 no.4
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    • pp.934-943
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    • 2019
  • A current balance problem exists in multi-phase LLC converters due to the resonant parameter tolerance. This paper presents a current balancing method for interleaved three-phase half bridge LLC converters. This method regulates the phase shift angle of the driving signals between the three phases based on a converter with a floating Y-connection. The floating midpoint voltage has different influences on each phase current and makes the three-phase current balance performance better than midpoint non-floating systems. Phase shift control between modules can further regulate the midpoint voltage. Then three phase current sharing is realized without adding extra components. The current distributions in a midpoint non-floating system and a midpoint floating system are compared. Then the principle and implementation of the proposed control strategy are analyzed in detail. A 3kW prototype is built to verify the validity and feasibility of the proposed method.

Trellis-coded .pi./4 shift QPSK with sliding multiple symbol detection흐름 다중심벌검파를 적용한 트렐리스 부호화된 .pi./4 shift QPSK

  • 전찬우;박이홍;김종일
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.2
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    • pp.483-494
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    • 1996
  • In this paper, we proposed the receive decoder and Virterbi algorithm with sliding multiple symbol detection using MLSE. the informationis transmitted by the phase difference of the adjacent channel signal at the .pi./4 shift QPSK. In order to apply the .pi./4 shift QPSK to TCM, we use the signal set expansion and the signal set partition by the phase differences. And the Viterbi decoder containing branch mertrice of the squared Euclidean distance of the first, second and Lth order phase difference is introduced in order to extract the information in the differential detection of the Trellis-Coded .pi./4 shift QPSK. The proposed Viterbi decoder and receiver are conceptually same to the sliding multiple symbol detection method using the MLSE. By uisng this method, the study shows that the Trellis-Coded .pi./4 shift QPSK is an attractive scheme for the power and the bandimited systems while also improving the BER performance when the Viterbi decoder is employed to the Lth order phase difference metrics.

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Phase Shift Control for Series Active Voltage Quality Regulators

  • Xiao, Guochun;Teng, Guofei;Chen, Beihai;Zhang, Jixu
    • Journal of Power Electronics
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    • v.12 no.4
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    • pp.664-676
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    • 2012
  • A phase shift algorithm based on the closed-loop control of dc-link voltage implemented on a series active voltage quality regulator (AVQR) is proposed in this paper. To avoid pumping-up the dc-link voltage, a general phase shift compensation strategy is applied. The relationships among the operation variables are discussed in detail, which is very important for guiding the design of both the main circuit and the control system. Then on the basis of an investigation of the dc-link voltage pumping-up from viewpoint of the active power flow, a novel phase shift control method based on the closed-loop of the dc-link voltage is proposed. This method can adjust the phase of the output voltage gradually and automatically according to the dc-link voltage variation without introducing a phase jump. The effectiveness of the proposed strategy is verified through simulations of a single-phase 5kVA prototype and laboratory experiments on both a single-phase 5kVA and a three-phase 15kVA prototype.

Series Connected DC/DC Converter for Fuel Cell System using Variable Phase Shift Switching Method (가변 위상변위 스위칭방식을 적용한 연료전지용 변압기 직렬형 DC/DC 컨버터)

  • Park, Noh-Sik;Kwon, Soon-Jae;Park, Sung-Jun
    • The Transactions of the Korean Institute of Power Electronics
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    • v.13 no.6
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    • pp.461-468
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    • 2008
  • This paper presents a novel series connected DC/DC converter and a proper variable phase shift switching method in order to obtain high voltage ratio for fuel cell system. The proposed series connected DC/DC converter has same rectifier and LC filter for DC output voltage, so it can reduce the number of passive devices regardless of the converter number. In the conventional constant phase shift switching method, the proposed series connected DC converters have inverse bias output voltage. In order to overcome this problem, a simple but proper variable phase shift switching method is proposed in the a novel series connected DC/DC converter. In order to verify the proposed system, simulation and experiments are implemented.

Determination of the Frumkin and Temkin Adsorption Isotherms of Hydrogen at Nickel/Acidic and Alkaline Aqueous Solution Interfaces Using the Phase-Shift Method and Correlation Constants

  • Chun, Jang-H.
    • Journal of the Korean Electrochemical Society
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    • v.15 no.1
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    • pp.54-66
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    • 2012
  • The phase-shift method and correlation constants, which are unique electrochemical impedance spectroscopy techniques for studying the linear relationship between the phase shift ($90^{\circ}{\geq}-{\varphi}{\geq}0^{\circ}$) vs. potential (E) behavior for the optimum intermediate frequency ($f_o$) and the fractional surface coverage ($0{\leq}{\theta}{\leq}1$) vs. E behavior, are proposed and verified to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and the related electrode kinetic and thermodynamic parameters. At Ni/0.5 M $H_2SO_4$ and 0.1M LiOH aqueous solution interfaces, the Frumkin and Temkin adsorption isotherms (${\theta}$ vs. E) of H for the cathodic hydrogen ($H_2$) evolution, interaction parameters (g), equilibrium constants (K), standard Gibbs energies (${\Delta}G^0_{\theta}$) of H adsorption, and rates of change (r) of ${\Delta}G^0_{\theta}$ with ${\theta}$ have been determined using the phase-shift method and correlation constants. A lateral repulsive interaction (g>0) between the adsorbed H species appears. The value of K in the alkaline aqueous solution is much greater than that in the acidic aqueous solution.

Phase Shift Analysis of 6Li Elastic Scattering on 12C and 28Si at Elab = 318 MeV

  • Kim, Yong Joo
    • New Physics: Sae Mulli
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    • v.68 no.12
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    • pp.1331-1337
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    • 2018
  • We present a three-parameter phase shift model whose form is the same as that of Coulombmodified Glauber model obtained from Gaussian nuclear densities. This model is applied to the $^6Li+^{12}C$ and the $^6Li+^{28}Si$ elastic scatterings at $E_{lab}=318MeV$. The calculated differential cross sections provide quite a satisfactory account of the experimental data. The diffractive oscillatory structures observed at forward angles can be explained as being due to the strong interference between the near-side and the far-side scattering amplitudes. The optical potentials for two systems are predicted by using the method of inversion. The calculated inversion potentials are found to be in fairly good agreements with the results determined from the optical model analysis in the surface regions around the strong absorption radius. We also investigate the effects of parameters in the three-parameter phase shift model on the elastic scattering cross sections.

Performance Evaluation of Islanding Detection Method by Phase Shifted Feed-Forward Voltage in Steady-State Grid Condition (전향보상 전압의 위상 변화를 통한 단독운전 검출 방법의 계통 정상 상태의 성능 평가)

  • Kim, Dong-Uk;Kim, Sungmin
    • The Transactions of the Korean Institute of Power Electronics
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    • v.23 no.6
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    • pp.373-380
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    • 2018
  • This study proposes a new islanding detection method that uses the phase shift of feed-forward voltage and evaluates the performance of an existing method and the proposed method when the grid frequency changes within the allowable range under steady-state conditions. The investigated existing method, which is slip mode frequency shift (SMS), uses current phase shift to detect islanding. The SMS method supplies reactive current to the grid under this condition, but the proposed method does not generate additional reactive power because it does not depend on the current control loop. The performance in steady-state grid condition is evaluated through simulations and experiments.

Minimize Reactive Power Losses of Dual Active Bridge Converters using Unified Dual Phase Shift Control

  • Wen, Huiqing;Su, Bin
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.654-664
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    • 2017
  • This paper proposed an unified dual-phase-shift (UDPS) control for dual active bridge (DAB) converters in order to improve efficiency for a wide output power range. Different operating modes of UDPS are characterized with respect to the reactive current distribution. The proposed UDPS has the same output power capability with conventional phase-shift (CPS) method. Furthermore, its implementation is simple since only the change of the leading phase-shift direction is required for different operating power range. The proposed UDPS control can minimize both the inductor rms current and the circulating reactive current for various voltage conversion ratios and load conditions. The optimal phase-shift pairs for two bridges of DAB converter are derived with respect to the comprehensive reactive power loss model, including the reactive components delivered from the load and back to the source. Simulation and experimental results are illustrated and explained with details. The effectiveness of the proposed method is verified in terms of reactive power losses minimization and efficiency improvement.

Measured Intensity Control Method of a Phase-shift Measurement Based Laser Scanner by using APD Bias Voltage Characteristic (위상 검출 방식 레이저 스캐너의 APD bias 전압 특성을 이용한 검출신호세기 제어 방법)

  • Jang, Jun-Hwan;Yoon, Hee-Sun;Hwang, Sung-Ui;Park, Kyi-Hwan
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.10
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    • pp.1096-1100
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    • 2012
  • In the phase-shift measurement method, the distance light travels can be obtained based on the phase difference between the reference signal and the measured signal. When the object having various colors is measured, the intensity of the measured signal much varies even at the same distance, and it causes different phase delay due to wide dynamic range input to a signal processing circuit. In this work, an measured intensity control method is proposed to solve this phase delay problem.

Theoretical analysis of the transmission gain spectrum of a phase-shift-controlled DFB tunable filter (위상 천이 조정 DFB 파장 가변 필터의 투과 증폭 스펙트럼에 관한 이론적 해석)

  • 김부균;정기숙;이봉영
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.7
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    • pp.205-215
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    • 1996
  • We derive the analytic equations for the transmission gain spectrum of a phase shift controlled (PSC) DFB filters with complexed coupled gratings considering both facet reflections and the phase of gratings using the transfer matrix method. The number of parameters of the equations is reduced by using the parameter of effective phase shift defined by the sum of the phase shift in a PSC region the effect of both facets reflections and the effective phase shift on the transmission gain spectrum and verify the validity of those equations from the computer simulation results. Computer simulation results show the PSC DFB filter with a pure index coupled grating has the widest tunable range and that with a pure gain grating has the largest side mode suppression ratio.

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