Vibro-acoustic modal model of a traction motor for railway applications

Abstract

A vibro-acoustic modal model of a traction motor for railway applications is presented based on an experimental modal analysis of the system. Noise requirements for railway traction motors are getting more and more demanding as part of the overall levels of new rolling stock. It is therefore of great interest to understand and predict the vibro-acoustic behaviour of electromagnetic noise generated by traction motors. The modal parameters are derived from an experimental modal analysis. The primary source for the radiated sound of the tested traction motor is the radial deflections of the stator shield. The modal parameters for the radial deflections are implemented in a reduced order modal model in a state space format using Matlab/Simulink. Only the structural modes that have a match in both the frequency and the spatial domain with the excited electromagnetic force will cause important vibro-acoustic response. This makes it possible to create an accurate and efficient reduced order modal model with only a fraction of the total number of structural modes. The simulation results from the modal model are compared to measurements of operational deflection shapes and acoustic measurements of the motor.