Sensorless Control of Railway Traction Motor in The Energy Point of View

Railway systems, especially electric railway, are more efficient compared to another mode of transportation. However, it consumes a lot of electrical power. Therefore, improving energy efficiency is a great interest to reduce operational cost. Traction motor consumes a lot of portion of energy in railway rolling stock. In this paper, the comparative study between Indirect Field Oriented Control (IFOC) sensored and IFOC-sensorless are studied in both performance and energy viewpoint to know which one has better efficiency. MRAS is chosen as speed estimator in sensorless method. Case studies with constant track and variable track were performed. The result shows that sensorless method using MRAS can be applied in railway application. However, its performance is decreases in braking mode shown by acceleration fluctuation. However, the speed performance is well. According to speed performance both methods have good result. In the energy point of view, sensored method resulted more energy from regenerative braking. From the total energy consumption, sensored method can save energy up to 33.76 % compared with sensorless method in constant track.

I. Introduction

Railway systems, especially electric railway, are more efficient compared to another mode of transportation [1]. However, it consumes a lot of electrical power. Therefore, improving energy efficiency is a great interest to reduce operational cost. Traction motor consumes a lot of portion of energy in railway rolling stock [2]. Fig. 1 shows the energy portion of an electrical multiple units (EMU), ICE 3, and a locomotive, Re 465, which show that traction motor contributes a lot of energy consumption. Two way to improve traction motor efficiency: first by using less loss type motor, second by improving traction motor control [1].