Harmonic Subspace and Sequence Mapping in a Series-Connected Six-Phase Two-Motor Drive

The torque and flux of sinusoidally distributed multi phase machines can be controlled by using only two stator d-q components. Thus, in these machines there exist additional degrees of freedom, which in multimotor drive systems are used to independently control a group of series-connected multi phase machines. Series connected machines share stator currents, therefore it is interesting to study how harmonics produced by non-linearities, faults or inbalance of the feeding system are distributed in the two-motor system, in terms of subspaces and sequences. This paper analyzes low-order harmonic distribution and its effects in a series-connected six-phase two-motor drive through experimental results collected from a laboratory setup.