Torque performance of optimally designed three- and five-phase reluctance synchronous machines with two rotor structures
SAIEE Africa Research Journal
Electrical Machines and Drives Laboratory, Department of Electrical and Electronic Engineering, University of Stellenbosch, Private Bag X1, Matieland (Stellenbosch) 7602, South Africa
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.
Copper loss; Cut out; Design optimization; Finite-element fields; Five-phase machines; Internal fluxes; Laminated rotors; Optimisations; Phase currents; Reluctance synchronous machine; Rotor structures; Third harmonic; Third harmonic current injection; Three-phase machines; Finite element method; Optimal systems; Poles; Structural optimization; Torque; Machine design