Induction Motors Versus Permanent-Magnet Actuators for Aerospace Applications

This paper introduces a comparative study on the design of aerospace actuators concerning induction motor and permanent-magnet motor technologies. In the analysis undertaken, the two candidate configurations are evaluated in terms of both their electromagnetic and thermal behaviors in a combined manner. On a first step, the basic dimensioning of the actuators and their fundamental operational characteristics are determined via a time-stepping finite-element analysis. The consideration of the thermal robustness of the proposed motor configurations is integrated in the design procedure through the appropriate handling of their respective constraints. As a result, all comparisons are carried out on a common thermal evacuation basis. On a second step, a single objective optimization procedure is employed, considering several performance and efficiency indexes using appropriate weights. Manufacturing and construction-related costs for both investigated topologies are considered by employing specific penalty functions. The impact of the utilized materials is also examined. The resultant motor designs have been validated through manufactured prototypes, illustrating their suitability for aerospace actuation.

1. Nomenclature

Magnetic reluctivity.

Magnetic vector potential.

Source current density.

Electrical conductivity.

Electric potential.

Coercive force of the permanent magnet.

Phase resistance.

End-winding inductance.

Stator current.

Supply voltage.

Active motor length.

Number of conductors.

Total conductor surface.

Total surface of conductors with positive phase current.

Total surface of conductors with negative phase current.

Tangential component of the magnetic force.

Mean tangential pressure.

Air-gap surface.

Electromagnetic torque.

Rotor radius.

Normal magnetic flux density component.

Tangential magnetic flux density component.

Angular coordinate.

Radial magnetic force density.

Design variable vector.

Length of the stator teeth.

Width of the stator teeth.

Width of the stator tooth tip.

Vector of initial values of the design variables.

Weight coefficients.

Mean electromagnetic torque.

Electromagnetic torque ripple.

Third and fifth normalized amplitude sum.

Copper losses.

Problem constraints.

Term associated with the winding fill factor.

Term associated with the slot shape.

Total technical cost.

Ratio of end-ring resistance to bar resistance.

Mechanical angle.

DC bus voltage.

Measured three-phase line currents.

-axis reference voltage.

-axis reference voltage.

Three-phase reference voltages.