Zonal Electro-Hydraulic Power Generation in Commercial Aircraft

This thesis investigates the approach of zonal electro-hydraulic power generation that replacing conventional central hydraulic systems by multiple smaller systems. Hydraulic power is generated by electric motor-driven pumps integrated in hydraulic power packages (HPP) and is supplied to specific zones of the aircraft. This enables to retain proven hydraulic actuators in future electric system architectures. Though, zonal systems impose new challenges like increased weight, higher thermal loading, higher noise emission, and their duty cycles differ considerably. To address these challenges this thesis proposes a dedicated zonal HPP concept using redundant speed variable EMPs with internal gear pumps combined with efficient system control strategies. There is no experience with the EMP technology in aerospace so that it is verified in experiments with a representative prototype first. Further, a dedicated electronic robust pressure control concept is developed to enable single and dual EMP operation that avoids the stability issues of today’s hydro-mechanical pressure compensators.
For exemplary zonal systems that supply main landing gear and primary flight controls, dedicated advanced system control strategies, comprising pump controlled actuation and load sensing, are developed to address system specific objectives: reduced peak power demand, lower thermal loading, and improved dynamic performance. The control concepts are verified in experiments on a system test rig incorporating the EMPs and the most relevant consumers. Finally, the overall system behavior and thermal aspects are analyzed in thermal-dynamic simulations. Based on the results key performance indicators like system mass and efficiency are evaluated and compared to a conventional system with a lower de.