【摘要】 近年来，双向LLC-DCX在电源系统中得到了越来越广泛的应用。为应对系统功率等级的提升，多模块并联成为实现系统扩容的重要方法。然而，均流性能是LLC谐振变换器并联系统的设计难点，各模块微小的谐振参数差异即可引起较大的电流不均衡。该文根据双向LLC谐振变换器的增益特性，定量分析双向LLC-DCX的并联特性，提出一种通过优化谐振网络参数提升并联均流性能的方法。最后，搭建一套三模块双向LLC-DCX并联系统样机，实验结果验证了所提方法的可行性和有效性。更多还原

【Abstract】 In recent years, bidirectional LLC DC transformers(DCX) have been widely applied in power supply systems. Multi-module parallel has become an important way to increase the power level of the system.However, the current sharing performance is the design difficulty of an LLC resonant converter parallel system.For LLC-DCX, if conventional current sharing methods are adopted, the fully decoupled modular parallel cannot be realized, and the current sharing control will reintroduce the control cost that has been saved. A current sharing method for a bidirectional LLC-DCX parallel system is proposed. By optimizing the resonant parameters,the natural current sharing performance of the converter can be improved, and the fully decoupled and modularized open-loop current sharing can be realized, which can simplify the control and reduce the cost to the maximum extent.Firstly, according to the equivalent circuit of the bidirectional LLC converter, the gain characteristics of the bidirectional operation are derived. Next, the forward parallel characteristics of bidirectional LLC-DCX are quantitatively analyzed. According to the forward equivalent circuit, the external characteristic curve equation is derived, and the expression of the current imbalance of each module in the forward parallel system is further derived. The current imbalance is composed of two parts. The first part is related to the no-load output voltage deviation of each module, and the second part is related to the internal resistance deviation of each module.According to the forward gain characteristics, the analysis shows that increasing the inductance ratio can optimize the impedance distribution of the resonant network, then reduce the first part of the current imbalance.Therefore, we can calculate the value range of the inductance ratio according to the requirement, then optimize the design of resonant parameters, to improve the current sharing performance of the forward parallel system.Next, the reverse parallel characteristics of bidirectional LLC-DCX are quantitatively analyzed. Similarly, the expression of the current imbalance of each module in the reverse parallel system is derived. Because the reverse no-load output voltage is constant, the current-sharing performance is only related to the internal resistance deviation. Therefore, the reverse parallel system naturally has a good current sharing performance without requiring to design of resonant parameters.Finally, a prototype of a three-module bidirectional LLC-DCX parallel system is built for the experiment. After optimizing resonant parameters, the current sharing performance of the forward parallel system is improved.Before and after the resonant parameter optimization, the reverse parallel system has good current sharing performance, and there is no noticeable difference. The forward parallel system and reverse parallel system have good dynamic current-sharing performance. The experimental results verify the feasibility and effectiveness of the proposed method. By optimizing the resonant parameters, the fully decoupled and modularized open-loop current sharing can be realized in a bidirectional LLC-DCX parallel system.更多还原