一种具有自动均流特性的并联LLC谐振变换器

A Parallel LLC Resonant Converter With Automatic Current Sharing Characteristics

在大功率低压大电流应用中,常将多路变换器并联运行以提高效率和可靠性。由于LLC谐振变换器的增益对元器件参数非常敏感,因此并联运行时,各路之间由于器件参数不一致引起的均流问题较突出。通过减少均流误差源的办法,该文提出一种具有自动均流特性的并联LLC谐振变换器。利用共用谐振电容、耦合谐振电感,该谐振变换器无需增加额外的元器件和控制策略,便可自动实现较好的均流特性。建立该变换器的均流误差时域模型,分析在谐振电感、谐振电容和励磁电感出现不对称情况下的均流误差分布特性。与传统的并联LLC谐振变换器比较,仿真和实验研究结果均表明所提出的并联LLC谐振变换器能产生较好的均流特性,与理论研究的结果一致。

With low-voltage and high-current,it is often to run the converter in parallel to improve its efficiency and reliability in high-power applications.Since the gain of the LLC resonant converter is very sensitive to component parameters,current sharing problem caused by inconsistency of component parameters between each phase is more prominent when working in parallel.Based on the principle of reducing the sharing current error source,there was a parallel LLC resonant converter with automatic current sharing characteristics presented in this paper.With the resonant capacitors common using and the resonant inductors coupling, there was a better current sharing characteristics can be automatically achieved without any other additional components or control strategies.In this paper,the time domain models of the converter were established and the characteristics of the current sharing error were analyzed when the resonant inductances,resonant capacitors and excitation inductances appeared asymmetry.Compared with the traditional parallel LLC resonant converter,the results of simulation and experiment showed that there were better current sharing characteristics achieved in the proposed parallel LLC resonant converter under the same condition,which was in high agreement with the theory deduction.