Torque performance of optimally designed three and five phase reluctance synchronous machines with two rotor structures

In this paper, the torque performance of optimally designed 3- and 5-phase reluctance synchronous machines with different rotor structures are studied with sinusoidal currents. The rotor structures are the internal flux barrier rotor (IFBR) and the rotor with no internal flux barriers but only cut-outs (CRR). The torque performance of 5-phase machines is also investigated with sinusoidal-plus-third-harmonic current injection. The finite element (FE) calculation method is used directly by the optimisation algorithm (Powell method) to optimise in multi-dimensions the design of the reluctance machines under same copper losses and volume. From the FE results it reveals that under same copper losses and volume, optimised sinusoidal machines (3-phase & 5-phase) with the same rotor structure, result in almost the same torque. The results also show that the reluctance machines with the IFBR develop higher torque in comparison to the machines with the CRR. For the five phase machines with sinusoidal-plus-third-harmonic current, there is a slight increase in torque for the machine with the CRR and a decrease for the machine with the IFBR