三相双降压逆变器中电感的磁集成方式比较与优化设计

Comparison and Optimal Design for Magnetic Integration Methods of Inductors in Three-Phase Dual-Buck Inverters

三相双降压逆变器克服了传统桥式逆变器中桥臂功率管直通的问题,可靠性高,但输出滤波电感数量多、体积大,利用磁集成的技术可以减小磁性元件的体积重量,提高系统功率密度。针对该问题从电感耦合方式的角度入手分析不同磁集成方案,从电路原理上讨论各方案的可行性及电感对进网电流波形和电路运行特性的影响。据此提出一种同名端相连不完全耦合的电感集成方案,其等效的三电感形式和传统双降压拓扑中两电感在电路中工作特性一致。和已有的磁集成方案及不采用任何磁集成方案相比,该方案在电感体积和滤波效果等方面均得到优化。最后设计并搭建一台15 k V·A的三相双降压并网逆变器原理样机进行实验验证,实验结果与理论分析吻合。

The three-phase du al-buck inverter has higher re lia bility as it overcomes the straight-legproblem existing in the tradition al bridge inverter. How ever, many output filte rin g inductors are needed in thetopology, which causes bulk capacity. Magnetic integration is a good way to reduce the volume and weight of them agnetic components and im prove the power density of the system. In this paper, analysis of differentintegration methods is carried out considering inductor coupling. The c irc u it princip le s are utilize d to discuss thepossibilities of various methods and the effects of the inductors to the current fed to the grid. Based on thediscussion, an optim ized method is proposed to integrate the inductors in an incom plete-coupling way w ithconnected dotted term in als, whose equivalent three inductors has id en tical characteristics w ith those of the twoinductors in the tradition al dual-buck topology. This method is better in aspects of the volume and filte rin geffects in comparison with the existed integration methods and discrete inductors. Finally the theory is validatedby a 15 k V ＊ A three-phase du al-buck grid-connected inverter prototype. The experim ent results are in consistentw ith the analysis.