Multi-Dimensional Approach to Multi-Phase Space Vector Pulse Width Modulation

A space vector PWM (SVPWM) technique for multi-phase voltage source inverters (VSI), based on a multi-dimensional space approach, is presented. The additional degrees of freedom, which appear as the number of phases increases, make the SVPWM more complex because VSI space vectors are not in a single two-dimensional space (as in three-phase case) any more. Existing approaches are based on n-dimensional space decomposition into (n-1)/2 two-dimensional sub-spaces. The methodology proposed here is different since the voltage space vectors are selected on the basis of criteria that are formulated for the multi-dimensional space, so that all the two-dimensional sub-spaces are simultaneously considered. The paper details the mathematical analysis that establishes the necessary conditions for appropriate selection of the voltage space vectors in the multi-dimensional case. Different criteria for the general n-phase case are presented for the selection of the VSI space vectors and the methodology is verified by simulation of a five-phase VSI