Transient performance of linear induction machines following reconnection of supply

A frequency-domain approach for the transient modelling of a voltage-fed, double-sided sheet-secondary-type linear induction motor (l.i.m.) is discussed. The problem of sudden reconnection of the l.i.m. in the motoring and braking modes at different operating speeds is analysed using discrete Fourier transforms. Attention is focused on the transient currents and thrust pulsations immediately following the switching action. The computational considerations for efficient calculation of the time response of the machine are discussed. Experimental results pertaining to the switching-in of a 2.5 kW l.i.m. from a 3-phase supply are presented, and compared with the predicted theoretical results.