Equivalent circuits for single-sided linear induction motors

Single-sided linear induction motors (SLIMs) have lately been applied in transportation system traction drives, especially in the intermediate speed range. They have merits such as the ability to exert thrust on the secondary without mechanical contact, high acceleration or deceleration, less wheel wear, small turning circle radius and flexible road line. The theory of operation for these machines can be directly derived from rotary induction motors, but several issues involving the transversal edge and the longitudinal end effects, and half-filled slots at the primary ends, need to be investigated. In this paper, a T model equivalent circuit is proposed which is based on one-dimensional magnetic equations of the air-gap, where half-filled slots are considered by an equivalent pole number. Then, it deduces two-axis equivalent circuits to study the SLIM dynamic performance. The theoretical analyses have been validated by experimental results on SLIM prototypes.