Opportunities and Challenges of Electric Aircraft Propulsion Tagung Energiesysteme - Elektromobilität Dr.-Ing. Claus Müller - Brugg,

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1 Opportunities and Challenges of Electric Aircraft Propulsion Tagung Energiesysteme - Elektromobilität Dr.-Ing. Claus Müller - Brugg, Unrestricted siemens.com

2 Siemens flight test history Hybrid electric Diamond Aircraft estar 1 and estar 2 Fully electric Pipistrel WattsUp trainer Fully electric Magnus efusion Record motor SP260D in the Extra 330LE Page 2

3 Magnus efusion - fully electric aircraft propulsion system installed firewall-forward Magnus efusion maiden flight Summer 2016 Battery system Auxiliary system Controller Aircraft Data Empty weight including batteries and parachute MTOW 410 kg 600 kg Wingspan 8.4 m Electric Motor with Bearing Length Height 6.6 m 2.4 m Inverter Cooling Power N max DC-link voltage (nominal) Torque M Boost Propulsion System Data 45 kw MCP 60 kw MTOP 85 kw max rpm 350 VDC ( V) 324 Nm Battery Max. airspeed 10.1 kwh 97 KIAS Page 3

4 Flying testbed for ¼-MW class electric propulsion systems Extra 330LE - maiden flight summer 2016 MTOW Wingspan Aircraft Data 1000 kg 8.0 m Height 2.6 m Length 7.5 * m Wing area 10.7 m 2 Propulsion System Data + Source: flyer.co.uk PP max PP cont NN cont MM cont 260 kw 230 kw 2250 rpm 1000 Nm ηη Mot max. 95% mm Mot, including propeller bearing 50 kg Page 4 * As rated in the Extra 330LE

5 Short History of Electric Aircraft Propulsion MB-E1 Solair 1 LiIon/LiPo commercially available Taurus G4 egenius EXTRA 330LE E-FAN 1.0 E-FAN Page 5

6 On April 7 th, 2016, Airbus Group and Siemens AG have Signed a Long-Term Collaboration Agreement in the Field of Hybrid Electric Propulsion Systems Siemens is determined to establish hybrid-electric propulsion systems for aircraft as a future business. We believe that by 2030 passenger aircraft below 100 seats could be propelled by hybrid propulsion systems... Airbus Group CEO Tom Enders Both companies take a significant joint development decision Demonstrate the technical feasibility of various hybrid-electric propulsion systems by 2020 Assemble joint development team of some 200 employees Prototype propulsion systems ranging from a few 100 kw up to 10 MW and more for short, local trips with aircraft below 100 seats, helicopters or UAVs up to classic short and mediumrange journeys. Target: breakthrough innovation in aerospace e- mobility Page 6

7 We expect electric propulsion to be the standard solution by 2050 Outlook for electric propulsion market Increasing dominance of electric propulsion Today Experimental flight with small aircraft demonstrated 2018 Market entry for ultra-light and military due to less strict certification rules 2022 Market ramp-up for certified systems, e.g., two- and fourseaters 2025 Fully electric flying for medium range (energy storage capacity sufficient) 2030 Airlines offering scheduled flights based on hybrid-driven aircraft 2050 E-propulsion is the standard solution for all aircraft segments Today 2050 Source: market evaluation Page 7

8 Opportunities Total cost of ownership (ex.: Boeing ) )1 1. Operating Cost Reduction Reduced Fuel Consumption 2. Higher Market Acceptance (reduced Noise- und CO 2 -Emissions) 51% 20% 15% 14% 100% 3. New Airframe and Traffic Concepts Fuel Invest Crew Service, Insurance, etc. TCO Fuel is a Cost Driver 1) Source: market evaluation Page 8

9 Aircraft Propulsive Efficiency Turbofan Propulsive Efficiency Is a function of bypass ratio (BPR) High BPR lead to large fan diameters 1970 s: BPR=1 Large fans require higher landing gear Source: fra-spotterforum.de 2016: A320neo BPR=12 Source: Airbus / Aero Page 9

10 Aircraft Propulsive Efficiency Distributed Propulsion Larger total disc area (BPR) Reduced tip speed Thrust vectoring Redundancy Electric Propulsion is favorable for distributed propulsion Excellent scalability Very small nacelle diameter possible Page 10

11 Aircraft Propulsive Efficiency Free Stream Propulsion Propeller-wing-integration can increase lift du to increased kinetic stream energy Smaller nacelles for propulsion help to reduce total drag. Source: Diamond Aircraft Industries Page 11

12 Aircraft Propulsive Efficiency Boundary Layer Ingestion Providing a fan at the aft of the fuselage, the wake field can be compensated Significant reduction in fuel consumption possible Electric drives are favored for this application Source: Bauhaus Luftfahrt Page 12

13 Opportunities 1. Operating Cost Reduction Reduced Fuel Consumption 2. Higher Market Acceptance (reduced Noise- und CO 2 -Emissions) 3. New Airframe and Traffic Concepts Target Emissions can only be achieved by use of disruptive technology. CO 2 Emissions Enhancements of current technologies Biofuels und disruptive concepts (e.g. ) Jahr Flightpath 2050 EU Vision envisages a 75% reduction of CO 2 emissions per passenger mile 1) IATA technology roadmap, June 2013 Page 13

14 Opportunities 1. Operating Cost Reduction Reduced Fuel Consumption Distributed Electric Propulsion will enable new aircraft concepts 2. Higher Market Acceptance (reduced Noise- und CO 2 -Emissions) 3. New Airframe and Traffic Concepts 1) 2) 3) 4) 1) (Dezember 2015) 2) (July 2015) 3) (Dezember 2015) 4) (Dezember 2015) Page 14

15 Visions of future individual mobility in the air Source: Airbus Group Source: Terrafugia Source: Airbus Group Source: Lilium Aviation Page 15

16 New markets enabled by electric aircraft propulsion Uber vision: elevate Passenger transport in urban areas Aerial service on demand Source: Page 16

17 Challenges 1. Power Density 2. Safety 3. Environmental Conditions Page 17

18 Electric Motor Power Density Evolution in power density of electric motors Industrial induction motors kw/kg Forced ventilated traction motors kw/kg Liquid cooled automotive traction kw/kg PP MMMMMM 1/2 MW PP MMMMMM /mm MMMMMM = 0,87 kw/kg 2016 Siemens SP kw/kg 2025 Electric aircraft propulsion > 10 kw/kg PP MMMMMM 1/4 MW PP MMMMMM /mm MMMMMM = 5,2 kw/kg Page 18

19 Motor Weight Optimization Motor sizing and loading Mechanical Power Rotational Speed Active Length Bore Diameter Winding Factor Current Loading Air-gapflux density sine wave amplitude Internal Power Factor PP mm = nn ll ee dd ssss 22 ππ22 kk 22 wwww AA BB δδδδ ccccccφφ ii Optimization levers: Current loading High-end materials Motor topology Esson s number C Motor Data P cont = 261 kw n max = 2500 rpm M cont = 1000 Nm η 260kW = 95 % D = 416 mm L = 300 mm P/M ~ 5.2 kw/kg Page 19

20 Total component weight and efficiency Energy Storage Battery Packs Converter BMS 2) Storage Extended portfolio DC DC Core portfolio Generator 1) AC DC Power Distribution AC DC Motor 1) Turbine / ICE Power Generation Generator Inverter Controller Turbine/ICE 3) 1) E-machines are capable to fulfill power generation and/or propulsion depending on e.g. mission profile, requirements and/or mode of operation, 2) Battery Management System (BMS), 3) Internal Combustion Engine (ICE) Page 20 96% 98% 99% 98% 96% η=87,6% Power Distribution Propulsion Unit Circuit Breaker Motor Switches Inverter Cables Propeller Connectors Gearbox Propulsion System

21 Challenges 1. Power Density 2. Safety 3. Environmental Conditions Page 21

22 Lowest Failure Rates Target Failure Rates better than λ=10e-6 Propulsion must be fault operational Failure-oriented design Short-circuit current <= Nominal current Single Lane architecture not sufficient Multiple lanes to reduce excess power Page 22 Source: Bennet: Fault Tolerant Electromechanical Actuators for Aircraft

23 Safety oriented Development Standards Railway EN (RAMS) EN (SW) EN (System, Assessment) EN (Communication) Automotive ISO (System, SW, HW) Aviation SAE ARP 4761 (Safety Assessment) SAE ARP 4754 A (Devel. Process) ED12C DO-178C (SW) ED80 DO-254 (HW) Courtesy clip art International Safety Standard IEC61508 (System, SW, HW) Nuclear IEC61513 IEC60880 (SW) (System, SW, HW) Process Industry IEC61511 Medicine IEC60601 Machinery IEC62061 Military Def Stan 00-56, Page 23

24 Challenges 1. Power Density 2. Safety 3. Environmental Conditions Page 24

25 Environmental Conditions Low Pressure, Low Temperatures at ft. altitude Temperature: -56 C Qualified electric components Air pressure: ~200mbar Source: geogrify.net Page 25

26 Environmental Conditions Low Pressure, Paschen law 1cm gap breakdown voltage 30kV sea level 47000ft ft Precaution has been taken regarding Tracking Partial Discharging Arcing Source: MOOG aircraft group Large creepage and clearance distances Special insulation Page 26

27 Power Electronics Challenges Cosmic Radiation Single Event Effects (SEE) Single-Event-Burnouts (SEB) typical destructive phenomenon of cosmic radiation Particle rate at flight altitude is ~300 times compared to ground level. Particle cocktail is different to ground level Source: astronomy.nmsu.edu Measure: Severe voltage derating to match cut-off-voltage Page 27 Source: ABB Application Note 5SYA

28 Thank you for your attention Dr.-Ing. Claus Müller Head of CoC Aircraft Drives and Controls Siemens Corporate Technology CT N47P AIR AS ADC Internet siemens.com/corporate-technology Page 28