A new coupled-circuit model of a linear induction motor and its application to steady-state, transient, dynamic and control studies

In this thesis, aspects of a coupled-circuit model, and the steady-state, dynamic, transient and control performance of linear induction motors are studied. A new coupled-circuit model, based on quasi-one-dimensional electromagnetic field analysis, is developed. The concept of winding functions is used to calculate the LIM parameters. The secondary winding functions are derived from the air gap flux density obtained from Maxwell's equations. The end effects are automatically included in the machine parameters. The derived machine equations are simple and can be solved more easily than those for other models developed previously. The new model is capable of solving steady-state, dynamic, transient and control problems of a LIM, taking end effects into account.;The steady-state performance of LIM is calculated by using the derived machine equations, and the computed results are compared with test data. It is shown that the machine equations resulting from the new model yield close correlation with steady-state test results.;The new model is used to analyze the dynamic and transient performance of an urban transit LIM. The behaviour of the LIM during acceleration and deceleration, under fault conditions, in response to a step frequency change, and when connected to an inverter supply is studied. The LIM parameter changes and consequent transient behaviour brought on by sudden changes in rail top-cap conductivity, secondary rail discontinuity and the equivalent secondary sheet current are evaluated under various transient conditions.;The characteristics of LIM under slip frequency control for constant current, constant voltage conditions, and in both constant current and voltage drive regions are investigated. The performance of a novel pole changing LIM to produce improved thrust capability at high speed under slip frequency control is also studied. Finally, the closed-loop behaviour of the slip frequency control under constant current and constant V/f drives, open-loop behaviour under constant V/f control, and maximum thrust control are presented. Where possible, computer simulation results are compared to test measurements from operational linear induction motor drives.