In many applications, electric actuators are not subjected to a (constant) time independent load. Examples are actuators in mechatronic applications, robots, exoskeletons, etc. In the load profile of these applications a period DT of high load is followed by a period (1-D)T of low/no load. Where T is the fundamental period of the duty cycle. During the period of high load, a high current in the winding of the electric motor is drawn which results in a significant temperature increase. During the period of low (or even no -load), the winding can cool down. As a consequence, the increase of the temperature during the period of high load puts a thermal limit on the duty.
Phase change materials (PCM), have to property to capture a high amount of energy during the phase change. During the phase change, the temperature is maintained constant.
The aim of this work is to investigate if PCMs are capable to increase the peak load under variable duty cycles without exceeding the thermal limits of the winding insulation. In this analysis, the period T of variable duty will be varied and the effectiveness of the PCM will be studied will be evaluated.
This analysis will give insight for which ratio of the mechanical and thermal time constant, the PCMs are the most effective/suitable.
This evaluation phase change materials for cooling of electric motors under variable duty cycles will involve both simulations and experimental work. The experiments will be performed on an adapted (winding provided with PCM) standard actuator, and evaluated under rotation with variable loading.