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Energies 2018, 11(5), 1124;

Optimal Design of a High Efficiency LLC Resonant Converter with a Narrow Frequency Range for Voltage Regulation

School of Electrical Engineering, Wuhan University, Wuhan 430072, China
School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070, China
Authors to whom correspondence should be addressed.
Received: 24 March 2018 / Revised: 15 April 2018 / Accepted: 24 April 2018 / Published: 2 May 2018
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As a key factor in the design of a voltage-adjustable LLC resonant converter, frequency regulation range is very important to the optimization of magnetic components and efficiency improvement. This paper presents a novel optimal design method for LLC resonant converters, which can narrow the frequency variation range and ensure high efficiency under the premise of a required gain achievement. A simplified gain model was utilized to simplify the calculation and the expected efficiency was initially set as 96.5%. The restricted area of parameter optimization design can be obtained by taking the intersection of the gain requirement, the efficiency requirement, and three restrictions of ZVS (Zero Voltage Switch). The proposed method was verified by simulation and experiments of a 150 W prototype. The results show that the proposed method can achieve ZVS from full-load to no-load conditions and can reach 1.6 times the normalized voltage gain in the frequency variation range of 18 kHz with a peak efficiency of up to 96.3%. Moreover, the expected efficiency is adjustable, which means a converter with a higher efficiency can be designed. The proposed method can also be used for the design of large-power LLC resonant converters to obtain a wide output voltage range and higher efficiency. View Full-Text
Keywords: LLC resonant converter; frequency range; optimal design; gain; efficiency LLC resonant converter; frequency range; optimal design; gain; efficiency

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Luo, J.; Wang, J.; Fang, Z.; Shao, J.; Li, J. Optimal Design of a High Efficiency LLC Resonant Converter with a Narrow Frequency Range for Voltage Regulation. Energies 2018, 11, 1124.

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