Hybrid Electric Aircraft Battery Heat Acquisition System

The electric drive train or electric energy & power storage, conversion and distribution (ESC&D) system of a hybrid electric aircraft, even at high efficiency, will reject significant heat at relatively low temperature. Thus effective thermal management of the ESC&D system is critical to realizing the potential benefits of a hybrid electric aircraft as the thermal management system (TMS) can add excessive weight (heat exchangers and pumps) and impose excessive parasitic power consumption (pumps and fans) and drag (engine fan stream air and ram air) on the aircraft. A 5MW parallel hybrid configuration [1] supplies a representative set of requirements for the development of TMS technology. The ESC&D system is comprised of a 1780 kWhr battery system, 2×2.2 MW motor drives, 2×2.1 MW motors and the associated power panels and feeders. A study has been completed to develop the lowest weight, highest performance (least amount of thermal resistance) approach for acquiring cell level battery heat such that it can be cooled by an aircraft TMS supplied coolant. The baseline battery heat acquisition (HA) system, based on SOA automotive electric vehicle packaging is approximately the same weight as the battery cells themselves, thus doubles the weight of the battery package. Alternative approaches currently under study, have the promise of reducing this weight by >60%.