This article is part of the能源管理系列：探究电源密度
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您将学到什么：
- Types of converters used in hybrid-electric propulsion systems for electric aircraft.
- What is a starter generator?
- 更多电动航空器（MEA）设计的动力总成选项。
This article will take a deep dive into challenging, but innovative, high-power-density development technologies for electric aircraft that will significantly reduce noise and fuel-burning emissions in the atmosphere.
飞机行业正在努力降低运营和维护成本，并在朝着混合动力飞机（HEA），电动飞机（MEA）以及最终全电动飞机概念的概念时减少气体排放。让我们从Hea开始。
HEA概念通过使飞机推进力和辅助飞机电力系统的振荡极大地扩展了MEA的想法。这项工作将推动飞机电气化信封的极限。
杂种推进系统
Designers are using their knowledge and creativity to enable hybrid-electric propulsion, especially for larger commercial aircraft. A megawatt-class, lightweight, high-efficiency, high-density electric power system will be needed for increased performance and low carbon emissions.
HEA的高功率密度转换器
Electric aircraft propulsion designs will need to have higher fuel efficiency and lower noise pollution, in addition to much lower carbon emissions. One possible way to achieve these goals is to use a high-power-density, medium-voltage (MV), megawatt-level power converter.1这项工作的架构基于混合设计，该设计由三级活跃的中性点斜线（ANPC）拓扑组成。
达到高效率和高功率密度的最佳方法是使功率设计人员显着将直流总线电压从当前的270 V DC提高到2 kV DC。这种较高的电压将使从电源转换器到电动推进电动机延伸的较小，较轻的电缆。
此外，设计人员将需要将功率转换器的基本频率从400 Hz提高到大于1 kHz。因此，该设计还需要更高的频率转换器。
这种设计的最佳功率晶体管元素是在设计架构中使用硅卡比德（SIC）MOSFET以及SiC Gate驱动程序。2
使用SIC设备，优化的过滤器设计以及改进的机械包装将提高效率和功率密度。最终设计是3L-ANPC电源转换器的SIC/SI混合体。逆变器设计的高效率为99.1％，高功率密度超过18 kVa/kg和10 mVa/m3at nominal operating conditions.
HEA
目前，传统的航空运输系统不符合任何合理水平的绿色模式运输水平。欧盟有一项2050年飞行路计划，试图减少二氧化碳（CO）2) and nitrogen-oxide (NOx) emissions per passenger kilometer by 75% and 90%, respectively, relative to the turn of the New Millennium.
一个发展t underway is the E-Fan X ground demonstrator in a joint effort by Airbus and Rolls-Royce. It’s a hybrid-electric propulsion system with a 2-MW electric drive powered from a 2.5-MW generator, which, in turn, is powered by a gas turbine located in the aircraft fuselage. Ground testing is continuing at present.
下一步是什么？
制造混合动力飞机飞行涉及电机的连续功率密度和效率，这将有助于飞机推进和发电。不过，推进和一代都需要超越目前的最新状态。
在这一点上，迄今为止，Mark＃1，2.5兆瓦的永久磁力（PM）发电机似乎是最好的有希望的想法。下一个高功率发电机的下一个级别将具有挑战性。但是，有一个持续的概念，即4兆瓦（或5-mVA），15,000 rpm的发电机正在努力达到18 kW/kg，这将是一种新的纪录水平。3
Electric-Aircraft Power Electronic Converters
功率密度在飞机电力电子转换器（PEC）中至关重要。5电动飞机的低重量和高功率作为关键目标至关重要。简单地提高PEC的速度并不总是有效地提高功率密度。较高的频率会导致铁和交流铜损耗的显着增加，以及对PEC性能的更高要求，这将对体重和大小产生负面影响。
伤口场同步机（WFSM）的最大功率可以达到250 kVa。一个示例是波音787 Dreamliner Architecture中的四个同样额定的WFSM。总电力为1,450 kVA（这也包括额外的发电设施）。该电源估算中包括两个主要发动机上的两个可变频率启动发电机（VFSG）。
A variable-speed variable-frequency (VSVF) power system (i.e., ‘‘frequency-wild ac system’’) seems to have attracted lots of interest. The first commercially available implementation of this system uses four 120/150-kVA variable-frequency (VF) generators in the Airbus A380 platform. The VSVF technology also is being deployed on the Boeing B787.
最重要的是，“可变电压”巴士策略的提议可能会增强整体电力管理系统。还提出了竞争性的DC-BUS拓扑，对于某些替代航空技术，有540 V和270 V。
Electric Aircraft Starter Generators (S/G)
更高的功能，例如集成的，高功率密度，开胃剂设计，5will be key technologies in the future more-electric-aircraft (MEA) system design. Gas turbines are being configured to perform electric starting (aka engine cranking) via electrical machines (EMs), that in turn will harvest mechanical power from the engine in the generator mode. This will enable elimination of hydraulic and pneumatic systems.
MEA Electric Powertrains
The Ultimate Goal: All-Electric Powertrain
In this future design concept, a set of battery energy-storage devices will be the only energy source. This design leads to zero emissions. To make this concept a reality, better state-of-the-art energy-storage devices will be needed. Stay tuned.
混合电动动力总成
In this concept, onboard aircraft energy will be supplied via jet fuel and electric energy-storage devices（见图）。使用这样的系统，可以通过电动机和喷气发动机执行飞机推进。
涡轮动力总成和分布推进
The turboelectric powertrain architecture has two sub-categories: full turboelectric and partial turboelectric. Both architectures don’t require energy-storage devices in their design. As a result, state-of-the-art ac-ac power converters could be used to interface the two machines and eliminate dc-bus electrolytic capacitors that are prone to fault problems. Just like the Series Hybrid Powertrain architecture, the full turboelectric topology implements an electric motor as the propulsion device.
With this method, the motor is powered by the electric energy provided by the onboard, high-power-density electric generators, which are in turn driven by the jet engines. Alternatively, the partial turboelectric architecture uses the jet engines and electric motors to provide propulsion power.
美国宇航局：绿色航空
NASA’s Ames Research Center支持航空科学技术的关键任务。绿色航空的目标是提高飞机燃油效率，并开发新技术和系统的工艺工艺，这些过程可以实现全球碳中性航空运输的未来。
NASA的目标是对航空对环境的影响承担责任。这将包括减少碳足迹和其他有害排放以及噪音。MEA开始使用电力总成。
概括
飞机电气化将大大减少航空旅行中的碳足迹。航空公司正在慢慢脱离喷射动力航空，并将在将来开始推出电池供电的飞机。在此期间，一些商业航空公司正在部分部署HEA。
High-power-density aircraft generators are methodically being deployed on HEA and ultimately on the MEA. NASA efforts will help speed up the introduction of HEA and MEA as we progress into the future of aviation and ultimately move toward the all-electric aircraft.
参考
1. “High Power Density Medium-Voltage Megawatt-Scale Power Converter for Aviation Hybrid-Electric Propulsion Applications,” 2019.
2.“ IGBT＆SIC GATE驱动程序基础知识”，Texas Instruments 2021。
3. “4-MW Class High-Power-Density Generator for Future Hybrid-Electric Aircraft,”IEEE Transactions on Transportation Electrification，卷。7，第4号，2021年12月
4.“在飞机上迈进更多的电力总成：技术挑战和进步，”电机和系统上的CES交易，卷。5，第3号，2021年9月。
5.“更多电动飞机的高功率机和启动器发电机拓扑：技术前景”，2020年7月24日。
