Axially laminated reluctance motor: analytical and finite-element methods for magnetic analysis

This paper describes two methods - one numerical, the other analytical for analyzing an axially laminated reluctance (ALAREL) motor. The numerical method, finite-element analysis (FEA), is generally used for estimation of the motor magnetic loading and capability for given stator currents. The accuracy of the FEA prediction is confirmed by a comparison between computed and measured magnetic quantities. The analytical model allows a rapid evaluation of the flux density in different parts of the motor, as well as of the capability for given stator current. It uses a distributed parameter network. The paper compares the results obtained from this network with those obtained from FEA. The methods agree well. Finally, the paper uses the two methods to investigate the effect of the quality of the magnetic material as well as the effect on motor performance of a nonuniform distribution of the laminations in the rotor. It shows that, with grain-oriented steel and nonuniformly distributed laminations, a higher flux linkage can be obtained. Consequently, lower current is required to develop the same motor torque.