A SPICE-based lumped parameter thermal model with geometrically distributed elements for electro-hydraulic actuators

In highly exploited and integrated mechatronic systems the thermal design and management defines the maximum load case. The trend to move to higher power densities needs precise and reliable thermal models of electrical machines to determine the limits of new and thermally demanding use cases and/or gives design guidelines for future generations of the product. For the electro-hydraulic system investigated in this paper a mathematically lumped parameter model with geometrically distributed elements has been developed. The thermal properties of the elements are calculated with physical material properties according to their geometric sizes. This allows to implement a comfortable parameterized interface that facilitates an easy change of geometrical dimensions and material properties. Moreover sub-sections of the system can be grouped which allows modularized modeling - this possibility shows its strength when an electrical sub-system is combined with a hydraulic sub-system. Together with automated model generation the resulting SPICE model is well suited for parameterized optimization. The model applies to both transient and/or steady state temperature including the effects of heat radiation and air convection. Thus, fast and accurate calculation of the temperature distribution and heat flow is possible and has been validated by measurements on a test rig.