Cumulative thermal coupling modeling and analysis of oil-immersed motor-pump assembly for electro–hydrostatic actuator

The Electro–Hydrostatic Actuator (EHA) is applied to drive the control surface in flight control system of more electric aircraft. In EHA, the Oil-Immersed Motor Pump (OMP) serves as the core as a power assembly. However, the compact integration of the OMP presents challenges in efficiently dissipating internal heat, leading to a performance degradation of the EHA due to elevated temperatures. Therefore, accurately modeling and predicting the internal thermal dynamics of the OMP hold considerable significance for monitoring the operational condition of the EHA. In view of this, a modeling method considering cumulative thermal coupling was hereby proposed. Based on the proposed method, the thermal models of the motor and the pump were established, taking into account heat accumulation and transfer. Taking the leakage oil as the heat coupling point between the motor and the pump, the dynamic thermal coupling model of the OMP was developed, with the thermal characteristics of the oil considered. Additionally, the comparative experiments were conducted to illustrate the efficiency of the proposed model. The experimental results demonstrate that the proposed dynamic thermal coupling model accurately captured the thermal behavior of OMP, outperforming the static thermal parameter model. Overall, this advancement is crucial for effectively monitoring the health of EHA and ensuring flight safety.