Technical Reports

Design Studies on Iron-Core Synchronously Operating Linear Motors

  • 01
  • Dec
  • 1981
AUTHOR: Enrico Levi
OFFICE: RPD
REPORT NUMBER: FRA/ORD 81/74
SUBJECT: Evaluation
KEYWORDS: Inductor Motors, Claw-Pole Motors, Motor Design
ABSTRACT: This report concerns the design of iron-core synchronously-operating linear motors with passive rail track. Claw-pole and homopolar inductor motors were the 2 basic types considered. The work interacted strongly with that done by GE under separate contract, part of which involved construction and testing of 112 kW models. The principal conclusions were: 1. The homopolar inductor motor is the preferred form for the linear synchronous motor; 2. Two factors significantly influence the performance of the inductor type motor: a) flux leakage bridging the two armature halves in the interpolar space and b) iron saturation affecting preferentially the armature teeth under the poles. Both factors tend to decrease the difference in reluctance between the polar and the interpolar regions; 3. Although the weight of the inductor motor approaches that of the induction motor, a smaller power conditioner is required, tending to give the synchronous alternative a competitive edge; 4. The inductor motor has high lift and guidance forces almost independent of speed. One interesting by-product of this work was the development of a method, using conformal mapping, for finding the magnetic field for arbitrary magnetic potential distributions on the bounding surfaces. Another was the demonstration that, in saturation-limited machines, the output power is proportional to the square of the magnetic loading.
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