SAE AIR6139

Description / Abstract: This SAE Aerospace Information Report (AIR) considers the issue of power regeneration into the EPS of an aircraft. A series of options for dealing with this regenerative power are considered and arranged in categories. Advantages and disadvantages of each solution, including the existing solution, are included. Validated simulation results from representative Electrical Power systems are presented in order to demonstrate how some of the solutions may operate in practice and how power quality can be maintained during regeneration. The impact on changes to the electrical generation system are also highlighted in this AIR, as these changes may have an impact on the solution deployed and the wider impact on the design of engines and auxiliaries.

This AIR reviews concepts and excludes detailed discussions on power system design. These concepts relate to the More Electric Aircraft, cover both AC and DC systems and can be applied to both normal operating conditions or as fault mitigation.

Purpose

This AIR considers ways of dealing with power regeneration into the Electrical Power system (EPS) of an aircraft. Some types of loads, notably actuators and motors, regenerate energy under certain operating conditions. The technology move to More Electrical Aircraft power architectures has significantly increased the number of loads which may regenerate electrical energy as well as the overall magnitude of the power generated on aircraft. At the time of writing, electrical specifications for aircraft systems do not allow significant regeneration into the EPS. This specification has resulted in all the motor drives with regenerative loads employing a large resistor, switch, and associated cooling in order to dissipate the regenerated energy. These resistors have to be rated for worst case operation, resulting in the weight of the equipment being far from optimized.