Rotary-linear induction motor composed of four primaries with independently energized ring-windings

In this paper, the authors propose a new type of tubular linear induction motor (TLIM) with two-dimensional motion. The proposed motor consists of plural short primary LIMs arranged on the same circumference and a common secondary. By adopting independently energized ring-windings to the primary, one can achieve both the reduction of coil-end region and the freedom of alternating current supply. The secondary conductor is capable of producing any one of rotary, linear and helical motions by controlling the phase of supply currents in each primary winding. From the three-dimensional (3-D) finite element analysis and experiments, the authors derive a primary scheme to increase the subsidiary rotary-force. In addition, they deduce an optimal arrangement of the primary slot currents enhancing the secondary thrust in the short primary LIM.