Lumped Node Thermal Modeling of EMA with FEA Validation

The development of electromechanical actuators (EMAs) is the key technology to build an all-electric aircraft. One of the greatest hurdles to replacing all hydraulic actuators on an aircraft with EMAs is the acquisition, transport and rejection of waste heat generated within the EMAs. The absence of hydraulic fluids removes an attractive and effective means of acquiring and transporting the heat. To address thermal management under limited cooling options, accurate spatial and temporal information on heat generation must be obtained and carefully monitored. In military aircraft, the heat loads of EMAs are highly transient and localized. Consequently, a FEA-based thermal model should have high spatial and temporal resolution. This requires tremendous calculation resources if a whole flight mission simulation is needed. A lumped node thermal network is therefore needed which can correctly identify the hot spot locations and can perform the calculations in a much shorter time. The challenge in forming an accurate lumped node thermal network is to determine all the suitable thermal resistances and capacitances of the thermal network. In this paper we present an FEA-based lumped node network and its simulation of a mission profile. This model is based on a detailed FEA model to locate the hot spots, to determine the network parameters and to verify its effectiveness. The model can also deal with the nonlinear behavior of the EMA system introduced by phase-change materials (PCM) if thermal energy storage is needed, and temperature-dependent magnetic properties. This model can also be incorporated into lumped node magnetic and electric model to develop a full multi-physics, multi-scale simulation engine. This engine can accurately analyze the complete EMA system in a systematic scale and whole-mission duration.