Chris M. Hutson Ganesh K. Venayagamoorthy Keith A. Corzine Optimal SVM switching for a multilevel multi-phase machine using modified discrete PSO. 1-6 2008 SIS https://doi.org/10.1109/SIS.2008.4668326 conf/swis/2008 db/conf/swis/swis2008.html#HutsonVC08