Edge effect and independently supplied slot currents in tubular linear induction motors

Abstract

The linear induction motor (LIM) is divided structurally into the flat and the tubular-type. This paper examines one kind of tubular linear induction motor whose primary configuration consists of four pieces of a flat-type core. We call this type of motor “the square tubular LIM.” The square tubular LIM has various merits of the cylindrical tubular LIM in addition to those of the usual flat-type LIM. The two remarkable features of the square tubular LIM that the flat-type LIM does not have are as follows. The first feature is that it has no edge effect, and the second is that the normal force in secondary conductor is cancelled by that of the opposite side of the secondary conductor. In comparison with the cylindrical tubular LIM, moreover, the square tubular LIM is easy to manufacture and maintain. The tubular LIM also has a feature that its primary winding is a kind of ring winding. Thus we can supply independently the primary current in each slot and hence easily obtain various winding schemes. Finally, the features of the square tubular LIM are studied. After numerically analyzing an experimental model, the motor is driven by the independently controlled slot currents, resulting in the expected performance.