Dynamic Vibrational Analysis of a Traction Inverter Housing

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One key aspect to be considered when designing an electric vehicle (EV) inverter is its dynamic response to vibrational loads. The source of these vibrational loads can be as simple as driving the vehicle, where the displacement of the suspension generates vibration that is transferred through the powertrain components, exciting the inverter. Additionally, with the increased adoption of integrated drives for EVs, the inverter is placed in close proximity to the motor or the gearbox, which can induce even more vibrations. Therefore, modal analysis is performed to extract the modal shapes and natural frequencies of the inverter. Ideally, an equipment should not be subjected to vibrations at its natural frequencies because that can lead to resonance, potentially causing a mechanical or operational failure. However, it is usually not possible to completely avoid the natural frequencies. In such cases, harmonic analysis is performed to understand the peak dynamic response of the inverter and ensure that it is within the operational limits. Nevertheless, only a few papers have discussed how to perform vibration analysis of traction inverters. Thus, this paper presents a brief overview of the fundamentals of mechanical vibrations, focusing on modal and harmonic analyses of a high-power traction inverter. Along with the vibration theory, simulation results carried out with ANSYS Mechanical are presented and used to assess the dynamic performance of the inverter under a wide range of vibration loads and excitation frequencies. The results indicate that the inverter is appropriate for in-vehicle operation and, although each inverter design presents different responses to vibrational loads, the results and assumptions adopted in this paper could serve as a reference for future work.