Space vector based Random Pulse Width Modulation scheme for a 3-level inverter in open-end winding induction motor configuration

In this paper a Random Pulse Width Modulation (RPWM) scheme for a dual inverter fed 3-level open-end winding induction motor based drive is presented. The proposed scheme is a variable switching frequency technique in which randomization is achieved by sampling the reference space vector at random intervals. Any reference space vector for the 3-level inverter is mapped into a vector of a basic 2-level inverter. For the mapped vector, randomization is done to achieve spreading of spectral characteristics. This space vector based method in the proposed scheme uses no sector identification. Switching time for actual switching vectors of the 3-level inverter is calculated for the vector mapped into the 2-level inverter and actual switching vectors are generated. No external circuitry is required for generation of switching signals. The proposed work is implemented in a 2 hp open-end winding induction motor based drive using TMS320LF2407 DSP platform and the experimental results are presented.