Light load efficiency enhancement of a LLC resonant converter

Qin, Jifeng; Moussaoui, Zaki; Liu, Jun; Miller, Greg

doi:10.1109/apec.2011.5744835

Cited by 12 publications

(6 citation statements)

References 2 publications

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“…To facilitate the calculation, a practical approximate condition is proposed: the time instant tx of zero crossing of ir2 is approximately a quarter of switching cycle from the rising edge of vGS5,8 at light-load conditions, as given in (15).…”

Section: B Calculation Of Voltage Gain and Rms Values Of Resonant Cur...mentioning

confidence: 99%

“…Hence, it's necessary and important to improve the light-load efficiency of bidirectional CLLC resonant converters. CLLC resonant converter faces similar light-load problems of low efficiency and unsatisfying voltage regulation as LLC converters [15][16][17], especially at high operation frequency. Conventionally, the output voltage of CLLC converter is regulated by modulating the switching frequency, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…To regulate the output voltage and improve the efficiency of resonant converters under light-load conditions, many control methods have been proposed [14][15][16][17][18][19][20][21][22]. Burst control [14,[18][19][20][21][22] is an effective way to adjust the voltage gain and raise the light-load efficiency by switching the converter between on and off state.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of Extended Phase-Shift Control for Full-Bridge CLLC Resonant Converter With Improved Light-Load Efficiency

Zhu

Zhuo

Zhao

et al. 2020

IEEE Trans. Power Electron.

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The CLLC resonant converters are drawing more and more attention for their superiority in soft switching, wide output range and symmetrically bidirectional operation. However, CLLC converter still suffers the problems of unsatisfactory voltage regulation and low efficiency under lightload conditions. Therefore, this paper proposes an optimization for extended phase-shift (EPS) control in full-bridge CLLC resonant converter to improve the light-load efficiency. In order to study the relations between phase-shifts of EPS control and converter efficiency, a detailed circuit model is first established to solve the voltage gain, time-domain expressions of main circuit variables and root mean square (RMS) values of resonant currents. Then, a comprehensive loss evaluation is conducted by calculating and analyzing the main power losses, including conduction loss, switching loss and core losses of magnetic components. Besides, zero voltage switching (ZVS) conditions of primary and rectifier switches are derived to define the range of soft switching. Finally, based on these analyses, the optimal combination of phase-shifts for EPS control is determined to achieve the maximum conversion efficiency of full-bridge CLLC converter at light-load conditions. The validity of the proposed optimized EPS control is verified on a 18~25V/400V, 200W GaN based CLLC resonant converter prototype.

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Section: B Calculation Of Voltage Gain and Rms Values Of Resonant Cur...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optimization of Extended Phase-Shift Control for Full-Bridge CLLC Resonant Converter With Improved Light-Load Efficiency

Zhu

Zhuo

Zhao

et al. 2020

IEEE Trans. Power Electron.

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“…Some methods attempting to adjust the voltage by changing the modulation strategies are proposed in literature. [10][11][12][13][14][15] In literature, [10][11][12][13] the burst mode strategy is employed in the converter to improve the performance at light load and the efficiency of the converter. However, this not only increases the control complexity but also brings low-frequency output voltage ripple and EMI problems to the system.…”

Section: Introductionmentioning

confidence: 99%

LLC resonant converter based on PFM and secondary‐side short‐circuit control for on‐board charger

Tang

Shi

Jiang

et al. 2022

Circuit Theory & Apps

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Commonly used lithium‐ion battery on‐board charger (OBC) for electric vehicles (EVs) needs a wide output voltage range, but the traditional LLC converter is hard to meet the need under the condition of high efficiency and high power density. In this paper, a resonant converter with hybrid modulation is proposed. The converter has a relatively simple topology and control method. Compared with the traditional LLC topology, only two diodes are replaced by MOSFETs on the secondary side of the transformer, and no auxiliary components are added. The primary‐side switches adopt PFM) and the secondary‐side switches adopt short‐circuit control in the proposed converter, which can realize a wide output voltage range, in a narrow switching frequency range with excellent soft‐switching performance. The proposed converter can effectively reduce the resonant current and the volume of transformer core and achieve energy delivery with high power density and high efficiency. The operation principles, voltage gain, and soft‐switching conditions of the converter are analyzed in this paper. Finally, a 3.3‐kW SiC‐based prototype with 400‐V input and 250‐ to 430‐V output is built to verify the feasibility and validity of the proposed converter.

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“…이러한 제품들을 동작시키기 위해서는 각각의 요구 전력에 알맞은 전원 공급장치가 필요하다. 각각의 전원 공급장치 시장들은 다양한 출력 요구 조건들을 제 시하고 있는데, 그 중 공통적으로 높은 전력밀도와 경 부하 시의 높은 효율, 그리고 대기모드에서도 일정한 출 력 전압 등을 요구한다 [1]- [4] . 이러한 [1], [5]- [8] .…”

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Analysis for Light Load Regulation of LLC Converter using Bode Plot

Yeon¹,

Moon²

2016

The Transactions of the Korean Institute of Power Electronics

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In general, LLC converters show great promise in applications that require high efficiency, especially under light load conditions. In particular, LLC converters feature wide gain capability with pulse-frequency modulation and zero voltage switching over entire load conditions. However, output voltage increases in light load conditions. In this study, Bode plot and impedance asymptotes analyses were conducted to obtain insights into the regulation characteristics of LLC converters under light load conditions. To improve the regulation characteristic of LLC converters, a new resonant tank with an additional capacitor is proposed. The design guideline for the proposed LLC converter is determined by the Bode plot and impedance asymptotes analyses. Therefore, the proposed LLC converter achieves the light load regulation while maintaining the advantages of typical LLC converters.

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Light load efficiency enhancement of a LLC resonant converter

Cited by 12 publications

References 2 publications

Optimization of Extended Phase-Shift Control for Full-Bridge CLLC Resonant Converter With Improved Light-Load Efficiency

Optimization of Extended Phase-Shift Control for Full-Bridge CLLC Resonant Converter With Improved Light-Load Efficiency

LLC resonant converter based on PFM and secondary‐side short‐circuit control for on‐board charger

Analysis for Light Load Regulation of LLC Converter using Bode Plot

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