Implementation of fault tolerant control for modular multilevel converter using EtherCAT communication

Modular Multilevel Converter (MMC) is very promising technology this days. It offers fault tolerant capabilities and ensures high efficiency with low output voltage harmonic content which results in need for smaller filter size. A disadvantage of the system is that the control becomes more cumbersome due to the high number of the employed submodules. A very efficient way to control the MMC is by using a real time communication platform between the sub-modules and a central unit. Thus, the central unit can deal with the overall control and some of the tasks can be distributed to the submodules. This communication platform has to ensure a perfect synchronization between the modules, and it should be also fault tolerant. The analysis of a MMC based on EtherCAT is presented in this paper from implementation and module fault point of view. The experimental tests show that the MMC operates after communication or module hardware fault occurred.