Speed and load torque observer application in high-speed train electric drive

This paper presents an application of induction motor mechanical speed and load torque observers in high-speed train drives. The observers are applied for a 1.2-MW electric drive with an induction motor. The goal of using such observers is to utilize computed variables for diagnostic purposes of speed sensors and torque transmission system. The concept of diagnostic system is presented in this paper, and proper criteria are proposed. The suggested system is designed to work without a speed sensor in the case of existing sensor faults. Monitored motor load torque is used to limit the maximum motor torque in the case of existing problems in the gearbox. The results of simulation and experimental investigations for a 1.2-MW induction motor drive are presented.