Current and loss for power module of modular multilevel converter

In order to perform the convenient system design for the power devices of voltage source converter( VSC) and the effective selection of parameters and cooling apparatus,it is necessary to carry out the effective estimation of current and loss. Through analyzing the working mode of newmodular multilevel converter( MMC),its current distribution was minutely analyzed. A simple loss calculation method for MMC based on the linear fitting of current distribution and element characteristic curve was proposed,and then the effect of such factors as the switching frequency and power factor on the MMC loss was analyzed. The simulated results showthat the proposed method can simply and effectively calculate the loss of various elements under different operating conditions,and the calculated results can provide some guidance for the selection of power devices and cooling apparatus.