Evaluation of radiated Electromagnetic Field Interference due to frequency switching in PWM motor drives by 3D finite elements

This paper investigates the effect of switching frequency of PWM motor drives on radiated Electromagnetic Field Interference (EMI). The excitation system for the radiated EMI evaluations consists of a high frequency PM machine model, a high frequency cable model, and a low frequency IGBT drive model. This system provides us with the conducted EMI currents through ground paths. The radiated EMI is modeled as a time harmonic electromagnetic wave which is propagated through all the components of the electric drive system. The Radiated EMI were evaluated by 3DFE analysis, using COMSOL multiphysics, with the conducted EMI currents as the supply source of the radiated fields. The results of the proposed 3DFE model follow expected patterns and provide a novel numerical alternative during the design and development stage of electric motor drive systems.