Modular multilevel converter with Half bridge submodule. This is my first project designed to demonstrate MMC capabilities. Final prototype consists of 4 sub modules per arm of each phase totalling 24 modules for all the three phases. This circuit is the design for single sub module. Each half bridge consists of an IPM module, isolated voltage supply, hall effect based voltage sensor, and shunt based current sensor. BOM is expensive but I am working on cheaper version of the MMCs. See gallary for the final prototype built inside a rack. AC-DC and DC-AC operations are tested successfully with grid connection. The prototype uses dSPACE controller but can be used with a simple DSP controller as well.

System sepcs:

Output 200V, 30A, 50Hz 3 phase.

Peak voltage 600V, Peak current 40A.

Gate driver is based on boot strap circuit with an additional input stage by an isolated DC-DC converter NDTS4815. It can withstand upto 5kV isolation. The operation of MMC for higher voltages is limited by this isolation withstanding capability as the supply IC on one side would see the mid point voltage of H Bridge sub module.