Parallel Current Sharing Control of LLC Resonant Converter Based on Virtual Impedance

Affiliation of Author(s):自动化学院

Journal:Diangong Jishu Xuebao

Abstract:In recent years, LLC resonant converter has been widely used because of its superior performance. The structure of parallel LLC resonant converter is very suitable for low voltage and large current applications, but it has the difficulty of current sharing between modules. A small difference in the parameters of the resonant network may cause large module current imbalance. In this paper, the virtual impedance is used to simulate the series impedance of the resonant network from the point of impedance. To improve the current sharing characteristics, the equivalent output impedance is adjusted by the series impedance. Taking two-parallel LLC module as an example, the control block diagram and the realization method based on the virtual impedance are given. Finally, using DSP digital control, a prototype of a two-phase parallel LLC resonant converter with 400V input and 12V/80A output is built. The experimental results show that the proposed control method can reduce the output current imbalance to 5% within the full load range, which verifies the proposed method. © 2019, Electrical Technology Press Co. Ltd. All right reserved.

ISSN No.:1000-6753

Translation or Not:no

Date of Publication:2019-11-10

Co-author:Wang, Yakun,Chen, Yu,Yue Chen,zzl,Jane Chen

Correspondence Author:Wang, Yakun,REN Xiaoyong

Date of Publication:2019-11-10