Partial Discharge Prediction Model for Electric Motors With Enameled Flat Wire

Recent high-specific-power electric machines (EM) in automotive applications operate at elevated voltages and in harsh environmental conditions. The resulting electrical and thermal stress makes the winding insulation system vulnerable to premature failure due to Partial Discharge (PD) activity. The main objective of the paper is the development and validation of a generalized Finite Element Model (FEM)-based PD prediction model for enamelled flat wires that can be accurately applied to different winding geometries. The PD prediction model is simulated for different insulation thicknesses and relative permittivity values based on Schumann criterion and the Townsend discharge mechanism. To ensure model fidelity, the influence of environmental factors, such as temperature, cooling oil, and impregnation material on the PD inception voltage (PDIV) is studied. Moreover, different electrical stresses, including switching frequency, risetime, and overshoot factor (OF), are considered. The experimental results obtained in the paper are fitted with the proposed model. The findings obtained from the combined FEM and experimental results approach provide essential guidance for designing robust, reliable insulation systems for next-generation electric powertrain applications.