Analysis of the effects of high coil temperatures on performance and drivability of electric sports cars

Abstract

Electric motors feature temporary high power densities. To avoid overheating, the allowable torque is derated dependent on temperature signals from thermal sensors. The investigation of thermal sensors in the coil ends with a special test device shows absolute and dynamic deviations. In this paper, the influence of deviations of the thermal sensor on performance and drivability of the vehicle is investigated.

The investigation is executed using simulation models of the vehicle and the electric motor. The model of the electric motor is a lumped-parameter thermal network which includes the thermal sensor. The absolute deviations of the thermal sensors are simulated by temperature offsets. Slow sensors which cannot follow dynamic temperature profiles result in overshooting temperatures. Thus the slowness must be compensated by a temperature offset.

The offsets due to absolute and dynamic deviations have to be combined to avoid overheating. The used thermal sensor of the examined electric motor causes a considerable loss of performance. The drivability is mostly influenced by the dynamic of the sensor. A slower sensor improves drivability but at the same time degrades the performance significantly.