Three-Phase Mission Profile Emulator for Multiple Submodules in Modular Multilevel Converter

This article proposes a highly efficient mission profile emulator (MPE) for submodules (SM) in modular multilevel converter (MMC), with respect to its basic circuit topology, control method and design. By using a common three-phase dc-ac power converter, as well as some analytical equations of MMC, the proposed MPE is capable of emulating operating conditions of multiple SMs in the MMC system. Compared with existing single-phase testing methods, the proposed three-phase structure achieves better testing efficiency. In the proposed MPE, two testing units of SMs, including four different mission profiles of submodule, are tested simultaneously with low requirements on dc power supply voltage. The comparisons between the complete MMC system and the MPE in the simulation, as well as experimental measurements, are given to verify the validity and accuracy of the proposed testing approach.