A five-level inverter voltage space phasor generation for an open-end winding induction motor drive

A topology for voltage space phasor generation equivalent to a 5-level inverter for an open-end winding induction motor is presented. The open-end winding induction motor is fed from both ends by two 3-level inverters. The three level inverters are realised by cascading two 2-level inverters. This inverter scheme does not experience neutral point fluctuations. Of the two 3-level inverters only one inverter will be switching at any instant in the lower speed ranges. In the multi level carrier based SPWM used for the proposed drive, a progressive discrete DC bias depending upon the speed range is given to the reference wave to reduce the inverter switchings. The drive is implemented and tested with a 1Hp open-end winding induction motor and the experimental results are presented.