Robustness and Sensitivity of Aging Models for Batteries and Electric Machines in Heavy-Duty Electrified Powertrains

This study evaluates the robustness and sensitivity of a Reduced-order battery aging model and a Dynamic thermal aging model for electric machines (EMs) in heavy-duty electric vehicles. The battery aging model is calibrated and validated using two datasets, with consideration of two temperature conditions and six charging/discharging rates (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{C} / 4$</tex>, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1 \mathrm{C}, 3 \mathrm{C}$</tex> at 23° C, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1 \mathrm{C}, 4 \mathrm{C}, 8 \mathrm{C}$</tex> at 30° C). The model estimates capacity degradation with good accuracy under both fast and normal charging scenarios, effectively capturing the degradation trends observed in experimental data. The estimated capacity degradation resulted in a best-case Relative Standard Error of Prediction (RSEP) of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${6. 2 1 \%}$</tex> and a worst-case RSEP of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${1 4. 2 5 \%}$</tex>. For the EM, four temperature profiles are utilized: two obtained experimentally by testing an EM under different conditions, and two generated by inputting distinct drive cycles into a range extender powertrain simulator. Using the experimental data, the Dynamic thermal aging model indicates a significant reduction in EM lifetime when exposed to prolonged high temperatures. For the simulated temperature profiles, the Federal Highway Driving Schedule (FHDS) results in a notable increase in lifetime loss due to extended exposure to elevated temperatures, whereas the HighEfficiency Truck Users Forum (HTUF) drive cycle shows a lower lifetime loss, attributed to reduced thermal stress.