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

Abstract

In this paper the torque performance of optimally designed three- and five-phase reluctance synchronous machines with different normal laminated rotor structures are studied. Both the round rotor with internal flux barriers and salient-pole rotor with no internal flux barriers but only cut-outs are investigated. The effect on the torque performance by adding third harmonic current component to the phase currents in a five-phase reluctance synchronous machine is also studied. The magnetostatic finite-element field solution with skew taken into account is used directly by an optimisation algorithm to optimise in multi-dimensions the design of the machines under same copper losses and volume. It is found that the torque increase due to third harmonic current injection is only 4% in the case of the five-phase machine with salient-pole rotor; the three-phase machine with round, internal-flux-barrier rotor is shown to outperform this machine in terms of torque by 28%. The measured torque results of the three-phase machine with round, internal-flux-barrier rotor are presented and compared with calculated results.Copyright © 2004 IEEE.