A method for real-time simulation of the noise and vibration of electric machines

Driver-in-the-loop vehicle simulation platforms are utilised to improve the vehicle design at an early stage, in particular with regard to noise, vibration and harshness. Here, a novel, real time simulation model applied to automotive electric motors is described, generating a capability to demonstrate noise and vibration from initial design decisions, avoiding experimental or emulated recordings. Thus, a rapid method for modelling sound and vibration of a brushed DC permanent magnet motor under various loads and speeds is shown. The motor can be controlled with a PWM signal or through direct current. To obtain the sound and vibration response at a specified load condition, which will be used for quick motor design/integration, a rapid and widely applied model is needed. Hence, in this work, a simplified model has been established for analysing the permanent-magnet machine in MATLAB/Simulink, achieving a real-time/quasi-real-time estimation of the sound radiation due to the internal magnetic force. The real-time internal magnetic force is calculated under both loading and unloading conditions in a simplified polar coordinate system with consideration of the stator slotting effect. Then, a simplified structural model is created using design data appropriate to an early motor design iteration, and the real-time sound radiation profile is estimated by the modal superposition model. This method is validated with the experiment for a DC motor but can be easily extended to other types of machines such as permanent magnet synchronous motors found in automotive electrical vehicles.