Soft start-up for high frequency LLC resonant converter with optimal trajectory control

Chao, Fei; Lee, Fred C.; Li, Qiang

doi:10.1109/apec.2015.7104412

Cited by 25 publications

(3 citation statements)

References 22 publications

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“…In that case, the peak of resonant capacitor voltage can reach (6V in -6nV o ), (8V in -8nV o ) and increases as an arithmetical ascending sequence until output voltage is heavily distorted. The phenomenon of ascending is analogous to the start-up issue in a dc-dc LLC resonant converter [35], which tends to energize the resonant tank rapidly during start-up and causes huge ringing. Therefore, the proposed SPDM utilizes two-pulse pattern to restrict every "energizing" process and stop before resonant voltage and current grow excessive.…”

Section: Spdm Regionmentioning

confidence: 99%

A Hybrid Modulation Method for Single-Stage Soft-Switching Inverter Based on Series Resonant Converter

Yeh

Chen

Lee

et al. 2020

IEEE Trans. Power Electron.

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Pseudo-dc-link inverters are promising due to the single-stage configuration. The inverters can be isolated by high-frequency transformers, which also provide the freedom of step-up/down through winding turns ratio. Conventionally, a pseudo-dc-link inverter is based upon a pulsewidth modulation converter like flyback converter, but the accompanying switching losses can degrade efficiency and overall system performance. Alternatively, resonant converters (e.g., series resonant converter) seem to fit the need as they typically display soft-switching characteristics. However, the relevant research results are scarce because of two main reasons: high resonant current and limited soft-switching range. To overcome the difficulties, a hybrid modulation method is proposed in this article for a pseudo-dc-link inverter based on series resonant converter. In high-line region, the inverter operates with variable-frequency modulation, which leads to zero-voltage switching and relatively low-resonant current. In low-line region, the inverter operates with a short-pulse density modulation so that switching losses are greatly curtailed without excessive resonant current. The merits in both regions together contribute toward the high efficiency of the inverter. This article presents the operational principle of the proposed modulation as well as a comparison with other modulation methods. In addition, a 400 V-230 V ac , 2-kW prototype was built to verify the proposed modulation and the peak efficiency reaches 98.0%.

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Section: Spdm Regionmentioning

confidence: 99%

A Hybrid Modulation Method for Single-Stage Soft-Switching Inverter Based on Series Resonant Converter

Yeh

Chen

Lee

et al. 2020

IEEE Trans. Power Electron.

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“…An approach called multi‐step SOTC could minimize the controller's resource usage. For high‐frequency LLC converters using low‐cost MCUs, it is possible to achieve soft start‐up, fast transient response, and other functions more efficiently [19–21]. To improve efficiency at light load, the primary side configuration of the LLC converter can be changed from full bridge (FB) to half‐bridge (HB), allowing the output of the LLC DC transformer (DCX) to step down from 12V to 6V [22].…”

Section: Introductionmentioning

confidence: 99%

“…An approach called multi-step SOTC could minimize the controller's resource usage. For high-frequency LLC converters using low-cost MCUs, it is possible to achieve soft start-up, fast transient response, and other functions more efficiently [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Transient response improvement of half‐bridge LLC resonant converter with full‐bridge rectifier for DC microgrid

Ma,

Cao,

et al. 2023

IET Renewable Power Gen

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LLC resonant converter has the features of low noise, high efficiency and power density, which is suitable to be integrated into DC microgrid. Due to severe stresses in the resonant tank, achieving fast and safe transient performance has been challenging for resonant converters. With less switch number and voltage stress, half‐bridge LLC resonant converter with full‐bridge rectifier (H‐F LLC resonant converter) are more suitable for high‐voltage application. To improve the transient response of the converter, this paper proposes a method based fixed center state trajectory for the converter to achieve soft start‐up. To reduce dynamic response time during start‐up, each step of fixed center state‐trajectory is designed optimally for the shortest path with symmetrical current limitation. In addition, the proposed method is also applicable to full‐bridge LLC converters. Moreover, according to the state‐plane analysis, load stepping‐up and stepping‐down transient state trajectories with the shortest path are carried out as well. To minimize the adverse effect of digital delay, fast load transient control based on 3D look‐up table is given based on FPGA‐EP3C25E144I7, which would also significantly reduce the computation requirement of the hardware controllers. The experimental results are verified on a 380V/12V LLC converter prototype at 130 kHz.

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A LLC Soft-Start Control Strategy Based on PSM and PFM

Niu

Xin

et al. 2022

Lecture Notes in Electrical Engineering

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Soft start-up for high frequency LLC resonant converter with optimal trajectory control

Cited by 25 publications

References 22 publications

A Hybrid Modulation Method for Single-Stage Soft-Switching Inverter Based on Series Resonant Converter

A Hybrid Modulation Method for Single-Stage Soft-Switching Inverter Based on Series Resonant Converter

Transient response improvement of half‐bridge LLC resonant converter with full‐bridge rectifier for DC microgrid

A LLC Soft-Start Control Strategy Based on PSM and PFM

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