LLCL型单相并网逆变器在不同滤波电感组合情况下的损耗计算

摘要

Along with application of the LLCL-filter,the working state of the large current ripple ratio for a gridtied inverter is catching more and more attention.The error may take place if the conventional efficiency analysis is adopted under this condition.In this paper,an integrated power loss calculation method is proposed,which is illustrated by analyzing the power loss of an LLCL-filter based single-phase grid-tied inverter using the discontinuous modulation.The expression of the inverter-side current of the inverter is deduced and it makes the power loss calculation more precise,where this method can be also adopted for the power loss calculation of the inverter using other modulation methods or with other type power filters.Furthermore,the efficiency curves under the different currentripple ratios are also given,which is much helpful for the selection of the LLCL-filter parameters.Finally,the calculation results are verified through the experiments on a 2 kW single-phase grid-tied inverter prototype.%随着LLCL型并网滤波器的提出,大电流纹波工况下工作的并网逆变器受到重视；此时,如果按传统方法进行逆变器的效率分析会带来偏差.本文提出了一套完整的并网逆变器的效率计算方法,并以采用不连续单极性调制的LLCL型单相并网逆变器为例进行了损耗分析与计算.具体推导了逆变器侧的电感电流表达式,然后根据IGBT的特性及制造商提供的特性参数,采取曲线拟合的方法来计算逆变器的损耗,这使得并网逆变器在大纹波电流条件下的效率计算更为准确,也对LLCL滤波器的初始设计或参数优化有着重要的指导性作用.该方法也适用于采用其他调制方式或其他滤波器的并网逆变器的损耗计算.最后,基于2 kW的单相并网逆变器平台,将理论分析结果与实验结果进行了对比验证分析.