Analysis of optimal operating points for electro-hydraulic energy system in aircraft mission profiles

Abstract: In the future, all-electric/more-electric aircraft will gradually adopt electric pump sources to replace traditional hydraulic systems centered on engine-driven pumps. The core components of the electric hydraulic energy system, namely permanent magnet synchronous motors and constant-pressure variable displacement pumps, have the problem of low efficiency at some operating points. Focusing on a typical electric energy system architecture, this paper studies the quantitative relationship between its efficiency and system states such as rotational speed, current, torque, pressure, and displacement. Moreover, with the goal of maximizing efficiency in the full load range, and taking motor speed and current as optimization variables, a calculation model for the optimal operating point is constructed within the scope of system design constraints. Finally, taking the electric hydraulic energy system of an actual aircraft as the research object, a state equation covering all its efficiency-related variables is established based on Matlab. With the optimization goal of the highest efficiency, the optimal combination of speed and displacement when the load flow changes in a wide range is given, and verified based on experimental data. Compared with the traditional constant-speed operation mode, the range of the high-efficiency operating area of the system can be increased by about 5.2 times after efficiency optimization.