VOLTAGE-FED INVERTER DRIVE FOR LINEAR INDUCTION MOTORS IN RAILWAY TRACTION.

The single-sided linear induction motor (SLIM) drive is studied for application to railway traction, especially for maglev transport. Its characteristics in the operation of a vehicle is analysed; a voltage-source inverter is assumed to supply the controlled current to the motors. The drive system for the HSST EXPO'85 maglev vehicle is studied. Theoretical results are compared with experimental data obtained during test operations. Calculated characteristics are verified with measured data. The dynamic interaction between SLIM's and the electromagnetic suspension system (EMS) is evaluated. The constant slip frequency control scheme can reduce the effects of the normal force caused by SLIM's but the value of the slip frequency should be chosen in relation with the extent of dynamic interference and energy efficiency of the system. The thrust ripple generated by the harmonics in the stator current has an influence on the dynamic behaviour of the EMS system and should be considered in the waveform control of the inverter.