Modeling and Control of a Dual Three-Phase Permanent Magnet Machine Accounting for Asymmetry between Two Winding Sets

In this paper, a dual three-phase machine is modeled with a general inductance definition considering machine saliency and asymmetry between two sets of three-phase windings. It is well known the αβ variables of a dual three-phase machine will be further transformed to the dq counterparts as a conventional three-phase machine, however, as for the xy and O
₁
O
₂
subspaces, the suitable rotational reference frames have not been studied adequately in the machine modeling level, which will be investigated from the view of resulting in a constant transformed inductance matrix. It shows the anti-synchronous reference frame would be the most proper choice in xy subspace for the isolated-neutral-points configuration. Quantitative relation among phase inductances and transformed inductances is deduced. When accounting for the asymmetry between two sets, additional coupling arises between αβ and xy subspaces, which may degrade the current control performance. The proposed model is examined by a dual three-phase flux switching permanent magnet machine, and then a current controller using the internal model control method is designed aiming at canceling the coupling due to asymmetry winding sets. Simulation verifies the effectiveness of the proposed mothed.