• Title, Summary, Keyword: LLC series resonant circuit

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Mathematical Analysis of LLC Series Resonant Converter with Current Doubler Rectifier using Coupled Inductor (Coupled Inductor를 활용한 배전류 정류 회로를 적용한 LLC 직렬 공진 컨버터의 수식화 해석)

  • Shin, Jung-Yoon;Hwang, Soon-Sang;Yoon, Byung-Chul;Kim, Hag-Wone;Cho, Kwan-Yuhl
    • The Transactions of the Korean Institute of Power Electronics
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    • v.19 no.5
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    • pp.440-449
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    • 2014
  • This study proposes an LLC series resonant converter with a current doubler using a coupled inductor as a rectification circuit for the secondary side. The current doubler circuit is generally used for a high-voltage input and low-voltage output circuit to obtain high efficiency with small transformer turn ratio. However, an inductive circuit is not generally used in the secondary side of an LLC series resonant converter. If inductive components exist on the secondary side, the resonant characteristics are changed through the secondary inductive circuit. Mathematical analysis shows that the secondary-side current doubler with coupled inductor is not affected by the resonant characteristic of the primary LLC if leakage inductance occurs in the coupled inductor. Results of the analysis are proven by simulation; an experiment is also conducted for the proposed circuit.

A Contact-less Power Supply using LLC resonant converter for Photovoltaic Power Generation System (태양광 발전 시스템을 위한 LLC 직렬공진컨버터 적용 무접점 전원장치)

  • Lee, H.K.;Lee, G.S.;Kang, S.I.;Kong, Y.S.;Kim, E.S.;Kim, Y.H.
    • Proceedings of the KIEE Conference
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    • pp.347-350
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    • 2006
  • The high efficiency full-bridge LLC resonant converter using a contact-less transformer is proposed for the photovoltaic power generation system. For the series resonance with a series capacitor, the LLC resonant converter utilizes the leakage inductance and magnetizing inductance of a contact-less transformer. Unlike the conventional series resonant converter operated to the continuous resonant current at above resonance frequency, the proposed converter operates to the discontinuous resonant current at the narrow frequency control range below resonance frequency. Due to the discontinuous mode resonant current, the proposed converter can be achieved the zero voltage switching (ZVS) in the primary switches and the zero current switching (ZCS) in the secondary rectification diodes without any auxiliary circuit. In this paper, the experimental results of the proposed full-bridge LLC resonant converter using a contact-less transfonner are verified on the simulation based on the theoretical analysis and the 150W experimental prototype.

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A Contact-less Power Supply for Photovoltaic Power Generation System (태양광 발전 시스템을 위한 무접점 전원장치)

  • Lee, Hyun-Kwan;Kong, Young-Su;Kim, Yoon-Ho;Lee, Gi-Sik;Kang, Sung-In;Chung, Bong-Geun;Kim, Eun-Soo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.11 no.3
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    • pp.216-223
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    • 2006
  • The high efficiency full-bridge LLC resonant converter using a contact-less transformer Is proposed for the photovoltaic power generation system. For the series resonance with a series capacitor, the LLC resonant converter utilizes the leakage inductance and magnetizing inductance of a contact-less transformer Unlike the conventional series resonant converter operated to the continuous resonant current at above resonance frequency, the proposed converter operates to the discontinuous resonant current at the narrow frequency control range below resonance frequency. Due to the discontinuous mode resonant current, the proposed converter can be achieved the zero voltage switching (ZVS) in the primary switches and the zero current switching (ZCS) in the secondary rectification diodes without my auxiliary circuit. In this paper, the experimental results of the proposed full-bridge LLC resonant converter using a contact-less transformer are verified on the simulation based on the theoretical analysis and the 150W experimental prototype.

Average Current Mode Control for LLC Series Resonant DC-to-DC Converters

  • Park, Chang Hee;Cho, Sung Ho;Jang, Jinhaeng;Pidaparthy, Syam Kumar;Ahn, Taeyoung;Choi, Byungcho
    • Journal of Power Electronics
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    • v.14 no.1
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    • pp.40-47
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    • 2014
  • An average current mode control scheme that consistently offers good dynamic performance for LLC series resonant DC-to-DC converters irrespective of the changes in the operational conditions is presented in this paper. The proposed control scheme employs current feedback from the resonant tank circuit through an integrator-type compensation amplifier to improve the dynamic performance and enhance the noise immunity and reliability of the feedback controller. Design guidelines are provided for both current feedback and voltage feedback compensation. The performance of the new control scheme is demonstrated through an experimental 150 W converter operating with 340 V to 390 V input voltage to provide a 24 V output voltage.

High-Efficiency and High-Power-Density 3-Level LLC Resonant Converter (고효율 및 고전력밀도 3-레벨 LLC 공진형 컨버터)

  • Gu, Hyun-Su;Kim, Hyo-Hoon;Han, Sang-Kyoo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.23 no.3
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    • pp.153-160
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    • 2018
  • Recent trends in high-power-density applications have highlighted the importance of designing power converters with high-frequency operation. However, conventional LLC resonant converters present limitations in terms of high-frequency driving due to switching losses during the turn-off period. Switching losses are caused by the overlap of the voltage and current during this period, and can be decreased by reducing the switch voltage. In turn, the switch voltage can be reduced through a series connection of four switches, and additional circuitry is essential for balancing the voltage of each switch. In this work, a three-level LLC resonant converter that can operate at high frequency is proposed by reducing switch losses and balancing the voltages of all switches with only one capacitor. The voltage-balancing principle of the proposed circuit can be extended to n-level converters, which further reduces the switch voltage stress. As a result, the proposed circuit is applicable to high-input applications. To confirm the validity of the proposed circuit, theoretical analysis and experimental verification results from a 350 W-rated prototype are presented.

Analysis of Hybrid Converter with Wide Voltage Range Operation

  • Lin, Bor-Ren
    • Journal of Power Electronics
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    • v.19 no.5
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    • pp.1099-1107
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    • 2019
  • A soft switching converter with wide voltage range operation is investigated in this paper. A series resonant converter is implemented to achieve a high circuit efficiency with soft switching characteristics on power switches and rectifier diodes. To improve the weakness of the narrow voltage range in LLC converters, an alternating current (ac) power switch is used on the primary side to select a half-bridge or full-bridge resonant circuit to implement 4:1 voltage range operation. On the secondary-side, another ac power switch is adopted to select a full-wave rectifier or voltage-doubler rectifier to achiever an additional 2:1 output voltage range. Therefore, the proposed resonant converter has the capacity for 8:1 (320V~40V) wide output voltage operation. A single-stage hybrid resonant converter is employed in the study circuit instead of a two-stage dc converter to achiever wide voltage range operation. As a result, the study converter has better converter efficiency. The theoretical analysis and circuit characteristics are verified by experiments with a prototype circuit.

An Optimization Design of the Diode Clamped Multi-Level Converter for Coaxial Inductive Power Transfer on the Low Voltage DC Micro-grid

  • Pairindra, Worapong;Khomfoi, Surin
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.333-344
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    • 2018
  • This proposed paper aims for the high efficiency contactless power transfer in household dc power distribution. A 300 W five-level diode clamped multi-level converter with 300 Vdc input dc link bus is employed for the power transferring task and the output voltage range is controlled at 48 Vdc. The inner and outer solenoid coils are used for inductive power transfer (IPT) transformer with the 200 kHz switching frequency for designed power density. Therefore, to achieve the converter efficiency above 95%, the LLC series resonant with fundamental harmonic analysis (FHA) and the calculated switching angles are used as an optimized tool for designing the system resonant tank. The validations of this approached topology are illustrated in both MATLAB/Simulink simulation and implementation.

Hybrid ZVS Converter with a Wide ZVS Range and a Low Circulating Current

  • Lin, Bor-Ren;Chen, Jia-Sheng
    • Journal of Power Electronics
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    • v.15 no.3
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    • pp.652-659
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    • 2015
  • This paper presents a new hybrid soft switching dc-dc converter with a low circulating current and high circuit efficiency. The proposed hybrid converter includes two sub-converters sharing two power switches. One is a three-level PWM converter and the other is a LLC converter. The LLC converter and the three-level converter share the lagging-leg switches and extend the zero-voltage switching (ZVS) range of the lagging-leg switches from nearly zero to full load since the LLC converter can be operated at fsw (switching frequency) $\approx$ fr (series resonant frequency). A passive snubber is used on the secondary side of the three-level converter to decrease the circulating current on the primary side, especially at high input voltage and full load conditions. Thus, the conduction losses due to the circulating current are reduced. The output sides of the two converters are connected in series. Energy can be transferred from the input voltage to the output load within the whole switching period. Finally, the effectiveness of the proposed converter is verified by experiments with a 1.44kW prototype circuit.

Current Unbalance Improved Half-bridge LLC Resonant Converter using the Two Transformers (두 개의 변압기를 이용한 전류불균형 개선 하프브리지 LLC 공진형 컨버터)

  • Yoo, Doo-Hee;Jeong, Gang-Youl
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.2
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    • pp.497-507
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    • 2010
  • This paper presents current unbalance improved half-bridge LLC resonant converter using the two transformers with different leakage inductances. The proposed converter resonates with the leakage inductance and magnetizing inductance of the transformer and the resonant capacitance. The converter operates in a wide load range and satisfies the zero voltage switching even under the light load. The series-parallel connected two transformers act as the transformers or the resonant inductances according to the operational modes, and the separate output filter inductance in the transformer secondary is not needed using the leakage inductance. The current unbalance of the secondary diode rectifier is improved using the different leakage inductances of the two transformers and the asymmetrical pulse-width modulation (PWM). In this paper, the operational principle of the converter is explained by the modes, and the design example for the prototype is also shown. To validate the performance of the converter, the prototype is implemented as the designed circuit parameters and the good performance of the proposed converter is shown through the experimental results

Interleaved ZVS Resonant Converter with a Parallel-Series Connection

  • Lin, Bor-Ren;Shen, Sin-Jhih
    • Journal of Power Electronics
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    • v.12 no.4
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    • pp.528-537
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    • 2012
  • This paper presents an interleaved resonant converter with a parallel-series transformer connection in order to achieve ripple current reduction at the output capacitor, zero voltage turn-on for the active switches, zero current turn-off for the rectifier diodes, less voltage stress on the rectifier diodes, and less current stress on the transformer primary windings. The primary windings of the two transformers are connected in parallel in order to share the input current and to reduce the root-mean-square (rms) current on the primary windings. The secondary windings of the two transformers are connected in series in order to ensure that the transformer primary currents are balanced. A full-wave diode rectifier is used at the output side to clamp the voltage stress of the rectifier diode at the output voltage. Two circuit modules are operated with the interleaved PWM scheme so that the input and output ripple currents are reduced. Based on the resonant behavior, all of the active switches are turned on under zero voltage switching (ZVS), and the rectifier diodes are turned off under zero current switching (ZCS) if the operating switching frequency is less than the series resonant frequency. Finally, experiments with a 1kW prototype are described to verify the effectiveness of the proposed converter.