THERMAL MODELING OF AN ELECTRIC MOTOR USED ON ROAD VEHICLE POWERTRAIN

2012 brings new European Union regulations concerning harmful emissions for road vehicles. The hybrid electric and electric mobility is a technology revolution for the automotive industry. In response to the stringent regulations and requirements enforced, vehicle manufacturers are developing new strategies, using hybrid electric or electric powertrain solutions. In order to obtain the goal of using alternative powertrain solutions, it is important to integrate from the early beginning different devices and to optimize their behavior. However, with a minimum of one electric motor architecture, a hybrid electric powertrain triggers more concerns surrounding energy flows. During operation, there are energy losses caused by heat generation. Generated heat, emphasized as losses, is having a negative effect on motor efficiency. Apart from the functional behavior of the electric motor, which is the production of torque/rotational speed, due to internal losses it also has a thermal behavior, which needs to be taken into account. Thereby this paper aims to present the thermal behavior of an electric motor in order to study the energy flows corresponding to the electric motor and to determine its efficiency. Based on thermal resistances, a thermal network was developed to compute internal losses for different parts of the motor. Using simulation, both the motor and its thermal model, were integrated in a mock-up virtual hybrid electric vehicle to study its behavior during a predefined cycle.