Design, Modeling, and Analysis of a Railway Traction Motor With Independently Rotating Wheelsets

A conventional railway vehicle adopts the rigid-axle wheelset (RW) due to its inherently characteristics of automatic restoration capability without additional actuators or control. RW allows the railway vehicle to run to the center of the rail. However, there is no restoring force in independently rotating wheelsets (IRWs), if only traction torque control is applied as in RW. As a result, excessive wear and noise between the rail and the wheel are generated, and in severe cases a derailment may occur. In order for IRWs to generate restoring force, an active control strategy is needed that controls the left and right wheel torques independently. Because of this control characteristic, unlike the conventional traction motor of RW, fast torque response and precise torque control performance are required. In this paper, the design and modeling of an IRW traction motor were accomplished considering active restoring force control. A quasi-semi-closed slot structure is proposed to improve the power density and restoring torque control performance. In the next step, control simulation was performed using a static interior permanent magnet synchronous motor model considering slot harmonics. The validity of the proposed methods was verified through experiments using a dynamo.