Rectifier Current Control for an LLC Resonant Converter Based on a Simplified Linearized Model

Zhijian Fang, Junhua Wang, Shanxu Duan, Liangle Xiao, Guozheng Hu and Qisheng Liu
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Zhijian Fang: School of Electrical Engineering, Wuhan University, Wuhan 430072, China
Junhua Wang: School of Electrical Engineering, Wuhan University, Wuhan 430072, China
Shanxu Duan: State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Liangle Xiao: China Electric Power Research Institute, Wuhan 430074, China
Guozheng Hu: School of Electrical and Electronic Engineering, Hubei Polytechnic University, Huangshi 435003, China
Qisheng Liu: School of Electrical Engineering, Wuhan University, Wuhan 430072, China

Energies, 2018, vol. 11, issue 3, 1-14

Abstract: In this paper, a rectifier current control for an LLC resonant converter is proposed, based on a simplified, two-order, linearized model that adds a rectifier current feedback inner loop to improve dynamic performance. Compared to the traditional large-signal model with seven resonant states, this paper utilizes a rectifier current state to represent the characteristics of the resonant states, simplifying the LLC resonant model from seven orders to two orders. Then, the rectifier current feedback inner loop is proposed to increase the control system damping, improving dynamic performance. The modeling and design methodology for the LLC resonant converter are also presented in this paper. A frequency analysis is conducted to verify the accuracy of the simplified model. Finally, a 200 W LLC resonant converter prototype is built to verify the effectiveness of the proposed control strategy. Compared to a traditional single-loop controller, the settling time and voltage droop were reduced from 10.8 ms to 8.6 ms and from 6.8 V to 4.8 V, respectively, using the proposed control strategy.

Keywords: LLC resonant converter; linearized model; rectifier current control; extended description function (EDF) (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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