Research on Current Sharing Control Method Based on Duty Cycle Regulation for Interleaved Parallel LLC Resonant Converters

• Published in: IEEE journal of emerging and selected topics in power electronics Vol. 12; no. 4; pp. 3977 - 3985
• Main Authors: Gao, Tian, Sun, Gang, Wang, Haoyue, Gao, Longxiang, Jia, Yetao, Xue, Wei, Yang, Yan
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.08.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Control methods; Current sharing; Current sharing control; Frequency conversion; Inductance; interleaved; LLC resonant converter; MOSFET; PWM; Rectifiers; Resonant converters; Resonant frequency; RLC circuits; Switching; Transmission circuits; Zero voltage switching; zero-voltage switching (ZVS)
• ISSN: 2168-6777; 2168-6785
• DOI: 10.1109/JESTPE.2024.3416749

Due to the particular advantages of the LLC resonant converter (e.g., high-efficiency and high-power density), it has been widely applied in both energy and power areas. The interleaved parallel structure LLC resonant converter can reduce the output ripple of a single LLC resonant converter and improve the upper limit of power capacity. However, there always exist parameters deviation between the parallel modules. As a result, the interleaved paralleled LLC resonant converter inevitably experiences power imbalance in each transmission circuit. To solve the problem, a new current-sharing control method is proposed in this work. The proposed method takes the conditions required for zero-voltage switching (ZVS) soft-switching characteristics of LLC resonant converters into consideration and adjusts the duty cycle of driving signals of two interleaving parallel LLC resonant converters independently, further realizes the power equalization of two-phase resonant converters. Extensive simulations and measurements are performed. It is found that the current sharing control method can reduce the current imbalance from more than 20% to less than 3% when the resonant inductance of the two interleaved LLC resonant converter deviates by 6.4% and the resonant capacitance deviates by 9.1%.