A Modified Fractional Level Modulation Strategy for Fractional Level MMC
The fractional level modular multilevel converter(FLMMC)can effectively improve the voltage quality of MMC with small quantities of submodules.However,the switching loss of FLMMC under existing fractional level mod-ulation(FLM)strategy is high.In order to reduce the switching loss of FLMMC,a modified FLM strategy including submodule energy balancing segment and submodule classification inserting segment was proposed in this paper.During the energy balancing segment,both the conventional submodule and the fractional level submodule participated in sorting and inserting at the time of each level change,so as to achieve energy balance between the two types of submodules.During the classification inserting segment,the conventional submodule and the fractional level submodule were sorted and inserted separately according to the integral level or the fractional level,so as to decrease the switching times of pow-er devices.Simulation results based on Matlab/Simulink and experimental results reveal that the proposed modified FLM strategy can significantly reduce the switching loss of FLMMC,and obtain excellent effectiveness in level multiplying.
万方数据
维普
