Multimode Optimization of the Phase-Shifted <i>LLC</i> Series Resonant Converter

Mumtahina, Umme; Wolfs, P.

doi:10.1109/tpel.2018.2803741

Cited by 31 publications

(3 citation statements)

References 21 publications

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“…With PSM, the equivalent input voltage is reduced and the voltage regulation range is extended [28]- [30]. Besides, PSM has also been used to suppress in-rush current during the start-up process [31], [32]. The above articles provide some control algorithms to enhance the efficiency or power density of LLC, but the 2DOFs are usually analyzed separately.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of LLC Resonant Converter With Two Degrees of Freedom Based on Operation Stage Trajectory Analysis

Xiao

Ning

et al. 2021

IEEE Access

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LLC resonant DC-DC converter has been widely used in high power density and high efficiency applications. Pulse frequency modulation (PFM) is commonly applied due to its wide soft-switching range. In some special cases, phase shift modulation (PSM) is applied to widen voltage regulation range, improve light-load efficiency, or implement a soft start-up process. Because LLC is with 2 control degrees of freedom (2DOFs), switching frequency and duty ratio, a unified analysis and optimization for LLC with 2DOFs is desired. This paper makes an effort to present a unified time domain operation stage trajectories (OSTs) analysis of LLC. On this basis, a unified numerical optimization method is proposed with arbitrarily designed optimization objectives. With the proposed optimization method, the optimized LLC with 2DOFs is with better performance compared to conventional PFM and PSM, which is verified by the experimental results.

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Section: Introductionmentioning

confidence: 99%

“…An analytical model has been proposed in [39], but not all possible modes are applicable. A multimode optimization of LLC in PSM is discussed in [31]. In short, most literature only focuses on PFM or PSM, and the comparison is not comprehensive since there is only one DOF in PFM or PSM.…”

Section: Introductionmentioning

confidence: 99%

Optimization of LLC Resonant Converter With Two Degrees of Freedom Based on Operation Stage Trajectory Analysis

Xiao

Ning

et al. 2021

IEEE Access

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“…To extend the ZVS range, a series of the full-bridge converters with various resonant tanks are presented. Among them, the converters with LC or LLC resonant tank are more attractive [14][15][16][17][18][19]. Nevertheless, the parameters of resonant tank should be selected carefully to achieve higher performance.…”

Section: Introductionmentioning

confidence: 99%

Performance Evaluation of a Semi-Dual-Active-Bridge with PPWM Plus SPS Control

2018

Electronics

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In this paper, a semi-dual-active-bridge (S-DAB) DC/DC converter with primary pulse-width modulation plus secondary phase-shifted (PPWM + SPS) control for boost conversion is analyzed in detail. Under the new control scheme, all effective operation modes are identified at first. Then, the working principle, switching behaviour, and operation range in each mode are discussed. Compared with conventional secondary phase-shifted control, PPWM + SPS control with two controllable phase-shift angles can extend the zero-voltage switching (ZVS) range and enhance control flexibility. In addition, an effective control route is also given that can make the converter achieve at the global minimum root-mean-square (RMS) current across the whole power range and avoid the voltage ringing on the transformer secondary-side at a light load. Finally, a 200 W prototype circuit is built and tested to verify correctness and effectiveness of theoretical results.

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Soft‐switching boundary and piecewise control of LLC converter with hybrid modulation

Liu,

Han,

Zhou

et al. 2024

Circuit Theory & Apps

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The voltage gain range of LLC converter can be effectively broadened by using the hybrid modulation of phase‐shift modulation (PSM) and pulse frequency modulation (PFM). However, the harmonic of resonant tank increases dramatically in PSM mode, and the first harmonic approximation is no longer suitable for solving the voltage gain. Moreover, the conditions for soft switching in PSM mode are not clear. Meanwhile, the small‐signal models of the converter in different modulation modes are quite different, and it is difficult for a fixed controller to ensure a good dynamic performance of the converter in both modulation modes. To address above issues, a voltage gain modeling method of PSM mode LLC converter is proposed. By establishing the function between input current and resonant current, the voltage gain model of the converter is obtained according to the power conservation. Moreover, considering the parasitic capacitance charge and resonant current commutation time, the condition for soft switching is derived. Furthermore, a control strategy of LLC converter in hybrid modulation is proposed. The piecewise proportional integral (PI) controller is adopted, and the parameters of the controller are dynamically adjusted with the modulation mode, so that the converter has excellent dynamic performance in both modes. And the hysteresis control is used to ensure the stability of mode switching. An experimental prototype with 200–340 V input and 28 V/1 kW output was built based on gallium nitride (GaN) devices. The peak efficiency was 97.82%, and the power density was 65.76 w/in3.

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Multimode Optimization of the Phase-Shifted LLC Series Resonant Converter

Cited by 31 publications

References 21 publications

Optimization of LLC Resonant Converter With Two Degrees of Freedom Based on Operation Stage Trajectory Analysis

Optimization of LLC Resonant Converter With Two Degrees of Freedom Based on Operation Stage Trajectory Analysis

Performance Evaluation of a Semi-Dual-Active-Bridge with PPWM Plus SPS Control

Soft‐switching boundary and piecewise control of LLC converter with hybrid modulation

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