Position Sensorless Control of Synchronous Reluctance Machines based on Fundamental Saliency Method for Railway Traction

Synchronous reluctance machines (SynRMs) have potential for high efficiency, and are beginning to replace induction machines for applications with low to medium power. SynRMs for railway traction require the machine design achieving high speed and torque. Such design has been enabled by recent development in numerical analysis, satisfying both the magnetic performance and mechanical strength. In addition, position sensorless control is widely used for railway traction to increase the reliability by removing position sensors and accompanying cables. To apply SynRMs to railway traction, instantaneous torque control for a wide range of the torque and machine speed is required based on position sensorless control. This paper applies position sensorless control of SynRMs to railway traction. Basic performance was validated with simulations. Through test runs, stable operation was for the first time demonstrated on a main track using real-size machines.