Control of Full Bridge Type Modular Multilevel Converter for Single Phase AC/AC Conversion

The Modular Multilevel Converter (MMC) with cascaded full bridge cells enables the multi-level output and has the big merit that the system is not required the transformers when it is used as a distributed power supply in high voltage system. The control method of the MMC for single phase AC-AC conversion system investigated in this study. The full bridge type MMC, which is expanded from the half-bridge type MMC and has 4 arm modules with multi-cells, is provided for AC-AC conversion. The control method of the system is theoretically analyzed. In the proposed control, the capacitor voltage control of the cells, the loop current control and the output voltage command can realize for the objective operation. And effectiveness of the proposed control method is presented by simulation results in typical cases.