基于电流过零点预计算的单有源桥变换器等效建模方法

Equivalent Modelling Method of Single Active Bridge Converter by Pre-calculating the Current Zero-crossing

模块化隔离型DC/DC变换器(modular isolated DC/DC converter,MIDC)作为光伏、风电等直流电源并网的重要方案,受到广泛关注。输入并联输出串联(input parallel output series,IPOS)型单有源桥(single active bridge,SAB)变换器是MIDC的常用拓扑之一,由于节点导纳矩阵阶数高、仿真步长小以及不控整流桥的存在,其电磁暂态仿真效率很低。文中提出一种基于电流过零点预计算的SAB变换器等效建模方法。首先,针对SAB变换器的拓扑结构和工作原理进行分析,求解不同模式下电感电流表达式。其次,计算电感电流过零点,并给出不同模式的区分条件。然后,类比DAB变换器,建立IPOS型SAB变换器的等效模型。在此基础上,利用Lyapunov法证明所提等效模型的稳定性。最后,在PSCAD/EMTDC环境中验证所提出模型的精度和加速比。

As an important scheme for grid connection of photovoltaic,wind power and other DC power sources,modular isolated DC/DC converter(MIDC)has received extensive attention.The input parallel output series(IPOS)type single active bridge(SAB)converter is one of the common topologies of MIDC.Due to the high node admittance order,low simulation step size and the existence of uncontrolled rectifier bridge,its electromagnetic transient simulation efficiency is extremely low.This paper proposed an equivalent modeling method of SAB converter by the pre-calculating current zero-crossing.First,the topology and working principle of the SAB converter were analyzed to solve the inductor current expression in different modes.Secondly,the expression of the zero-crossing point of the inductance current was given with the distinguishing conditions of different modes.Then,analogy to the DAB converter,the equivalent model of the IPOS type SAB converter was established.On this basis,Lyapunov method was used to prove the stability of the proposed equivalent model.Finally,the accuracy and acceleration ratio of the proposed model were verified in the PSCAD/EMTDC environment.