Sensitivity of TeDP Microgrid System Weight and Efficiency to Operating Voltage

Abstract

The development of turboelectric distributed propulsion (TeDP) systems requires the identification of operating voltage standards particular to this revolutionary airborne form of microgrid. This paper introduces a holistic approach for nominal operating voltage and voltage limit definition. Preferred nominal design voltage ranges were identified for the NASA N3-X DC superconducting TeDP system. This was accomplished by decomposing the architecture concept to the subcomponent and device level and integrating technology sensitivities into a system level parametric model. The effect of voltage on electrical system mass and efficiency are presented considering the potential effects of device improvements and protection system variations. Nomenclature AC= Alternating Current BSCCO = Bismuth Strontium Calcium Copper Oxide DC = Direct Current FBC = Force Balanced Coil LN2 = Liquid Nitrogen SFCL = Superconducting Fault Current Limiter SMES = Superconducting Magnetic Energy Storage TeDP = Turboelectric Distributed Propulsion TRL = Technology Readiness Level SSCB = Solid State Circuit Breaker UPS = Uninterrupted Power Supply YBCO = Yttrium Barium Copper Oxide

A Review of Concepts, Benefits, and Challenges for Future Electrical Propulsion-Based Aircraft

“…NASA's N3-X design study suggested adoption of a minimum voltage level of 6 kV in order to capture the system level weight reduction benefits [51,128]. In further pursuance, for a cryogenically cooled DC system, a voltage level of 4.5 kV is recommended when optimized for the system mass accounting detailed component mass, efficiency estimations in the system [178]. The SUGAR team design has made a selection for a 10 kV system architecture for the system studies [29,179].…”

Comparison of Candidate Architectures for Future Distributed Propulsion Aircraft

“…It is proposed that the full electrical system is a high temperature superconducting (HTS) cryocooled system, operating at 77K [15] (as far as is technologically possible) to reduce power losses associated with transitioning from an HTS system at 77K, to a warmer non-super conducting system [8]. It is acknowledged that any solid-state switching components within a distributed propulsion electrical architecture are unlikely to be superconducting, and assumed to operate at 100K [8].…”

“…It is acknowledged that any solid-state switching components within a distributed propulsion electrical architecture are unlikely to be superconducting, and assumed to operate at 100K [8]. Clearly the advantages of a superconducting power system must be traded against the mass and efficiency penalties attributable not only to the electrical components of the power system, but also the required cryogenic cooling system.…”

“…This paper compares three candidate architectures identified from the literature: DC [8], hybrid AC-DC [10] and AC [9]. For the DC architecture, the transmission system is AC between the electric machines and power electronics, and DC throughout the transmission and distribution system.…”

“…The rated power levels for all three architectures include a significant level of redundancy to allow for scenarios such as engine out or loss of up to two propulsor motors [8]. For the purposes of this study, the required power for rolling take-off is estimated to be 22.4 MW (30 000 HP) [17].…”