Abstract
Motor selection is important in all mechatronic systems. This requires understanding how motor performance degrades as a function of system temperature. In this paper, bond graphs are used to develop two simple motor models that captures this performance degradation, specifically by modeling the changes in system resistance and the motor constant as a function of system temperature. In the first system, the entire motor is assumed to be one thermal mass while in the second, the rotor and stator are modeled as two thermal masses separated by an air gap. The calculation of system temperatures allow for relevant system parameters to be represented more accurately over long periods of operation. Either model is readily integrated into models of larger mechatronic systems, a task made more simple through the use of bond graphs. The results presented in this paper will help future engineers to appropriately size motors for mechatronic systems based on such considerations as steady state temperature response, low versus high load conditions, and ambient operating conditions.
