This is the typical block diagram of a three-phase AC/AC converter to supply controlled power to a motor. The capacitors used in every main stage are highlighted. A star connection for the EMC filter is typical. The main purpose is to filter interferences coming from and to the grid. The DC-Link block is for smoothing and energy storage. The output IGBTs typically require snubber capacitors to protect the semiconductor from over-voltages provoked by the fast switching. The output filter will minimize the interferences generated by the IGBT module in order to provide the proper load current and voltage.