Phase-angle control of the repulsion/drive force ratio in two-phase linear induction motor with nonferromagnetic secondary

The repulsive/drive force ratio in a two-phase linear induction motor with a nonferromagnetic secondary can be changed over a wide range by changing the stator field from a travelling to a pulsating field. This can be achieved by controlling the phase angle between the two-phase currents of the stator. The stator electric loading of the unbalanced two-phase current system is derived, including the space harmonics due to the stator winding distribution. The magnetic field analysis is carried out on a three-region model using the magnetic vector potential. The force components acting on the conducting secondary sheet are calculated using Maxwell's stress tensor. The drive and suspension force components are plotted as functions of the slip, with the phase angle between the two-phase currents as parameter. The effect of the harmonic force components is also investigated. The induced voltages in the stator winding are determined, the stator voltage equations are established, and the corresponding locus diagrams are constructed for different values of the phase angle.