Dual three-phase permanent magnet synchronous machine supplied by two independent voltage source inverters

This paper investigates a dual three-phase permanent magnet synchronous machine supplied by two independent three-phase voltage source inverters (VSIs). Dual three-phase machines have many important advantages compared with their conventional three-phase counterparts. Instead of six-phase converters and special vector controls, it would be a very interesting alternative to supply these machines by two conventional three-phase VSIs since they are readily commercially available. This paper shows that the proposed supply method can be used successfully although it suffers from a decrease in the dynamic performance and an error in the estimation of torque. On the other hand, two independent VSIs do not cause low-frequency current harmonics and guarantee balanced current sharing between the winding sets thus avoiding the two most common problems with dual three-phase machines. Experimental results are provided to verify the conclusions. The results suggest that the simple supply method of two conventional VSIs could be a feasible alternative for many industrial applications.