As the goals of air transport shift towards more-electric or all-electric airplanes, different drive train configurations have been explored recently. A major goal on the way towards the inclusion in commercial air traffic is high reliability. One of the experimental electric airplanes is NASA’s X-57 “Maxwell”, which consists of fourteen electric motors powered from a battery pack. The aim of this paper is to assess the reliability of the proposed design of the X-57 by using the Lz-transform approach, as well as to propose several alternative designs to its electric drive train, in order to use less vehicle mass on the motors and more on the battery pack, without sacrificing the original availability and expected performance, with a final goal to increase the flight range. The reliability analyses show that the replacement of X-57’s three-phase motors with six-phase ones greatly improves availability of the electric drive train due to the use of fault-tolerant electric machines. Additionally, all of the further proposed alternative designs have higher availability than the X-57. The alternatives with CHB inverter topologies generally achieved higher availability values and higher expected performance than the B6 variants. Finally, the use of a distributed propulsion system with smaller take-off motors leads to a motor-mass advantage compared to more conventional drive train designs.

中文翻译：

---

基于Lz变换方法的NASA X-57电动飞机版本比较可靠性分析

随着航空运输的目标转向多电动或全电动飞机，最近人们探索了不同的传动系统配置。纳入商业空中交通的一个主要目标是高可靠性。其中一款实验性电动飞机是 NASA 的 X-57“麦克斯韦”，它由 14 个由电池组供电的电动机组成。本文的目的是通过使用 Lz 变换方法评估 X-57 拟议设计的可靠性，并提出其电动传动系统的几种替代设计，以便在车辆上使用更少的车辆质量电机等电池组，在不牺牲原始可用性和预期性能的情况下，最终目标是增加飞行范围。可靠性分析表明，由于使用了容错电机，将X-57的三相电机更换为六相电机，大大提高了电力传动系统的可用性。此外，所有进一步提出的替代设计都比 X-57 具有更高的可用性。采用 CHB 逆变器拓扑的替代方案通常比 B6 变体实现了更高的可用性值和更高的预期性能。最后，与更传统的传动系统设计相比，使用具有较小起飞电机的分布式推进系统具有电机质量优势。