Influence of Driving Behavior on Thermal and Lifetime Characteristics of Electric Machines for Automotive Applications

Increasing stress on power-dense electric traction machines is prompting scientists to intensify investigations into the reliability and lifetime of automotive drives in particular. Special focus is placed on the electrical insulation system, whose probability of failure increases sharply at higher stresses. The influence of physical parameters on the lifetime is investigated in many publications. There is consensus among scientists that high temperature significantly damages the insulation system of electric machines and leads to failures. In this article, the human influence is additionally investigated by considering three different driving behaviors. A mild, an average, and a sporty driver behavior is examined on a highway, a rural, and an urban driving cycle. The driving cycles are used as input to calculate the thermal effects in an initial model. As a further step, a lifetime model is developed on the basis of measured data, which indicates the lifetime as a function of the previously calculated temperature.