Acoustic near field of HV capacitor calculated from laser vibration measurements

This study presents a comprehensive methodology for calculating the acoustic near field of high-voltage (HV) capacitor using laser vibration measurements. Conducted in a semi-anechoic chamber with a Polytec Robovib system, the measurements involved over 14,000 discrete points on all radiating surfaces ensuring precise operational deflection shapes characterization. Utilizing 3D laser vibrometry (LV) scanning, the complex vibration velocities in all three spatial directions were meticulously measured on the capacitor surface. These velocities were then converted into normal velocity boundary conditions for finite element method (FEM) simulations aimed at accurately predicting near-field acoustic radiation. The point cloud data was imported into FEM software, which included a meshed sphere of acoustic elements to simulate acoustic propagation using real velocity vector excitations. The FEM model development was carried out using Comsol Multiphysics and Ansys Mechanical software, incorporating various empirical calculation approaches. This study provides a comparative analysis focusing on sound power levels, directivity plots, and the data post-processing efforts associated with each approach. The results include predictions of radiated power and directivity at frequencies of 50 Hz, 200 Hz, and 400 Hz.