Article
Engineering, Electrical & Electronic
Somnath Pal, Bhim Singh, Ashish Shrivastava
Summary: This paper presents a two-stage LED driver using a front-end boost converter operating in CrCM and a second-stage LLC resonant converter, providing PFC and stable output voltage for LED load. The system significantly reduces design complexity, improves efficiency, and is validated through experimental analysis.
INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Xuliang Yao, Xiao Han, Yuefeng Liao, Jingfang Wang
Summary: In this study, an improved circuit is proposed to solve the problem of voltage gain reduction in the LLC resonant converter under light-load conditions. The impedance model considering the parasitic parameters of the primary and secondary sides is calculated, and the limitations of the previous method are explained. The proposed circuit improvement effectively suppresses the voltage gain increase when the switching frequency reaches a certain level, as verified by experimental results.
Article
Engineering, Electrical & Electronic
Guidong Zhang, Junming Zeng, Wenxun Xiao, Samson Shenglong Yu, Bo Zhang, Yun Zhang
Summary: This article presents an advanced self-protected single-stage ac-dc LLC resonant converter, which introduces a diode for overvoltage prevention, achieving self-protection, cost reduction, and smaller size. The proposed converter also features power factor correction, soft switching, and a wide output voltage range. Detailed analysis and prototype experimentation have confirmed the effectiveness of the design.
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
SangCheol Moon, ChengSung Chen, Ren-Jye Wang
Summary: In low output voltage and high output current LLC resonant converter applications, synchronous rectification is crucial for high efficiency and power density. However, stray inductances in MOSFET package and PCB pattern can lead to premature turn-off of SR gate and large SR dead time. To address this issue and improve system efficiency, a hysteresis and dead time regulation control method is proposed, utilizing a mixed signal approach.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Somnath Pal, Bhim Singh, Ashish Shrivastava
Summary: This paper presents a two-stage high-power LED driving solution for an isolated LED load, utilizing a nonisolated Zeta converter for power factor correction and a half-bridge LLC resonant converter for delivering ripple-free DC voltage. A new primary-side regulation technique is implemented to reduce component counts in the feedback loop, ensuring stable DC-bus voltage and nearly unity power factor for driving a 150 W load with low harmonics distortion in the input current.
INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Jing-Yuan Lin, Pin-Hsien Liu, Hsuan-Yu Yueh, Yi-Feng Lin
Summary: The LLC converter is widely used in the power supply industry due to its high conversion efficiency. However, when operating at low loads, the converter experiences a decrease in efficiency and exceeds the specified frequency limit. To address this issue, a valley switching control (VSC) strategy is proposed, which effectively maintains output voltage regulation and reduces operating frequency, resulting in improved efficiency and power quality.
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
Qinglin Zhao, Jianmeng Zhang, Yuxia Gao, Deyu Wang, Qiuxia Yang
Summary: This article proposes a multimode hybrid LLC resonant converter with a wide output voltage range. The converter can operate in three different modes: low-gain mode, medium-gain mode, and high-gain mode, by controlling the drive signals of the primary switches. Variable frequency modulation is used in each mode, allowing for a smooth transition and achieving an ultra-wide output voltage range. The prototype of the proposed converter demonstrates good efficiency performance over the entire voltage range, with a peak efficiency of 97.5%.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Peyman Amiri, Chris Botting, Marian Craciun, Wilson Eberle, Liwei Wang
Summary: Synchronous rectification (SR) is crucial for achieving high efficiency in high output current LLC resonant converters. Existing SR control methods have limitations due to FET package stray inductance and variable on-time, but this research introduces an analytic-adaptive method that overcomes these challenges for improved efficiency. Experimental validation on a 300W 390/12V LLC resonant converter showed peak efficiency of 93.66%.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Li Dong, Pei Jiang
Summary: This paper proposes a voltage regulation strategy based on energy feedback for LLC resonant converters under extremely light-loading conditions, aiming to improve output voltage quality and extend battery life. By adjusting the feedback energy to the source, the proposed control method effectively minimizes output voltage ripple and enhances stability, demonstrating correctness and feasibility through experiments.
IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING
(2021)
Article
Energy & Fuels
Wenzhe Chen, Kangli Liu, Jianfeng Zhao, Cheng Jin
Summary: This paper proposes a disturbance-observer-based control approach for LLC resonant converters, which achieves better performance compared with the conventional PI controller. The approach incorporates a disturbance observer to estimate and compensate for uncertain effects resulting from external disturbances, circuit parameters variation, and model mismatch in a feedforward way. The main advantage of this control structure is that it can improve stability and dynamic response simultaneously.
Article
Engineering, Electrical & Electronic
Yuqi Wei, Quanming Luo, H. Alan Mantooth
Summary: LLC resonant converter, a popular isolated dc/dc converter, can achieve higher efficiency and system performance by adopting synchronous rectification technology to replace uncontrolled diodes with SR MOSFETs. This article provides a comprehensive overview of SR driving strategies, addressing the importance of SR, methods of generating driving signals, advantages and disadvantages, and future research directions.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Cheol-Hee Jo, Dong-Hee Kim
Summary: This paper proposes a reconfigurable LLC resonant converter for bidirectional electric-vehicle chargers. By designing the resonant inductors and the structure of the windings in the transformer, the proposed converter can achieve the monotonic voltage gain curves of a unidirectional LLC resonant converter in both charging and discharging modes. Experimental results show that the converter achieves maximum efficiencies of 96.86% and 95.95% in the charging and discharging modes, respectively.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Energy & Fuels
Tsvetana Grigorova, Aleksandar Vuchev
Summary: This paper discusses a simple method for controlling an LLC resonant DC-DC converter using a state space trajectory based on a linear combination of the voltage across the capacitor and the current through the inductance in the series resonant tank. The output, control and load characteristics of the converter, required for its design and application, are built for the different inductance ratios. Simulations confirm that the considered simple trajectory control provides a fast dynamic response and stable operation of the LLC resonant converter, even in cases of a significant change in the control.
Article
Engineering, Electrical & Electronic
Fei Liu, Xinbo Ruan, Xinze Huang, Yang Qiu
Summary: This article investigates the suppression of second harmonic current (SHC) in the front-end dc-dc converter using a DC transformer (DCX)-LLC resonant converter. A unified small-signal model and control scheme are proposed to reduce the SHC, improving the output impedance and ultimately achieving the desired goal.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Energy & Fuels
T. Saravanakumar, R. Saravana Kumar
Summary: This article introduces a three-phase interleaved step-up DC-DC converter for electric vehicles, which is efficient and cost-effective. The frequency response study and design technique of the converter are explained in detail, and the design models are validated using MATLAB/Simulink and OPAL-RT.
FRONTIERS IN ENERGY RESEARCH
(2022)