Analytical multiphysics methodology to predict vibroacoustics in PMSMs combining tangential electromagnetic excitation and tooth modulation effects

The vastly increased range of operating speeds and loads of Electric Vehicle (EV) traction motors, implies that the use of traditional Finite Element (FE) based Noise Vibration and Harshness (NVH) optimisation methodologies becomes challenging due to extensive computational loads. Thus, reduced order analytical methodologies have become of crucial significance for fast decision-making at pre-design stages. In this work, a novel combination of analytical techniques is utilised, to formulate a multiphysics methodology for Electromagnetic NVH prediction of typical high-speed Surface-mounted Permanent Magnet Synchronous Machines (S-PMSMs). Calculation of the electromagnetic stresses in open-circuit conditions was performed using the 2-Dimensional (2D) Complex Permeance methodology. Vibroacoustic predictions were made using analytical expressions for an equivalent 2D representing the stator. Unlike traditional analytical methodologies, further refinements were implemented to improve the accuracy of the vibroacoustic calculations without sacrificing computational efficiency, through a set of force transformation techniques. These allowed for consideration of the tooth modulation and tangential excitation effects, which are typically neglected in similar studies. The methodology was applied on a 48-slot 8-pole S-PMSM with electromagnetic and vibroacoustic results validated numerically. A fast parametric study was performed on the design parameters for the optimisation of the generated force harmonics, achieving significant reductions in the sound power levels at specific frequencies.