Identification scheme of maximum traction force using recursive least square for traction control in electric locomotives

The railway traction system that incorporates a slip controller provides a significant improvement in the adhesion between rail and train which can lead to increase in the traction force and wheel slip controllability. Due to the change of rail track and running speed, both slip and operating traction force keep changing. Therefore, there is a requirement of reliable identification of wheel-rail contact force properties and adhesion level for acceleration or braking controls to adapt to different track conditions. Since wheel slip controller shows many applications in the aspect of safety relevant features, such as slip control, emergency brake assistance, locomotive operation, etc. the proper estimation of traction force and the detection of maximum traction force between rail and wheels are very important factors in the railway industry. Furthermore, an advanced scheme with traction drive control is required to achieve the maximum adhesion level for a railway vehicle. This paper proposes a new identification technique scheme which is designed to regulate the torque reference according to the maximum traction force. The proposed scheme is built with Recursive Least Square (RLS) scheme to identify the peak slip level at maximum traction force with the searching technique based on the traction force estimated by a Kalman Filter. Furthermore, this scheme is also used to operate the traction system within the identified maximum traction force region. Simulation model validates that the proposed controller with identification scheme can control the train or locomotive to obtain its maximum adhesion force.