1 / 46

Regenerative Electric Flight Synergy and Integration of Dual-role Machines

Regenerative Electric Flight Synergy and Integration of Dual-role Machines J. Philip Barnes 25 Oct 2014. Animated slides: F5 key Also: View ~ "Notes Page". Great theoreticians and experimentalists (all Ph.D.).

warren-hines
Download Presentation

Regenerative Electric Flight Synergy and Integration of Dual-role Machines

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Regenerative Electric Flight Synergy and Integration of Dual-role Machines J. Philip Barnes 25 Oct 2014 Animated slides: F5 key Also: View ~ "Notes Page" Regenerative Electric-powered Flight J. Philip Barnes

  2. Great theoreticians and experimentalists (all Ph.D.) Ludwig Prandtl - Germany Albert Betz - Germany Photo Permission requested Photo Permission requested Academy of Achievement Royal Aeronautical Society Hermann Glauert - U.K. Paul MacCready - USA Regenerative Electric-powered Flight J. Philip Barnes

  3. Presentation Contents • Regen. elec. flight: Origin & Introduction • Dual-role machines: • Propeller and wind turbine • DC motor-generator • Brushless motor-generator • Integration: • Inverter-rectifier • DC boost converter • "Chop" Vs. "Boost" architecture • “Regenosoar” aircraft concept • Summary & Look Ahead

  4. Regen Aircraft Elements and Operation • Windprop • Fixed rotation direction • Sign change with mode • Thrust, Torque • Power, Current Motor-Gen (M-G) Power Electronics • Energy Storage Unit: • Battery and/or: • Ultra capacitor • Flywheel w/M-G Exploit opportunities to store Vs. expend energy Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  5. Presentation Contents • Regen. elec. flight: Origin & Introduction • Dual-role machines: • Propeller and wind turbine • DC motor-generator • Brushless motor-generator • Integration: • Inverter-rectifier • DC boost converter • "Chop" Vs. "Boost" architecture • “Regenosoar” aircraft concept • Summary & Look Ahead

  6. Propeller Wake, Pitch, and Blade Angles • Wake induces downwash • (normal to local section) • Pitch: • helix length per rotation • htip = 2 p R tan btip • Uniform pitch: • r tanb = R tanbtip • Blade tip angle (btip): • 14o ~ low pitch • 30o ~ high pitch Horseshoe Vortices R r • Effect of more blades (fixed T, R): • Steep blade angle, much lower RPM • Lower tip Mach, much-reduced noise • High torque → dual & counter rotation • Numerically integrate wake for loading Blade angle (b) at radius (r) is measured from rotation plane to the chord line at (r) Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  7. Test data validating Glauert's rationale on induced velocity F.E. Weick, Aircraft Propeller Design, McGraw-Hill, p. 102-103 Gradual buildup Immediate swirl, as predicted by Glauert Regenerative Electric-powered Flight J. Philip Barnes

  8. Rotor blade velocity diagram - "Pinwheeling" condition • Propeller or wind turbine • Angle of attack = 0 • No change to flow direction • No change to relative wind • Helical drag wake (unloaded) • wr tanb= Vo (all sections) • or, r tanb= const.=R tanbtip W2 Helical wake w r Blade section Looking outboard, Blade at 3 o’clock Vo Chord line Axial wind b Pinwheeling sets up "Betz Condition" • Propeller or turbine at no load Perturb w or Vo to load rotor • Helical wake (drag and/or vortex) • Sets blade angle distribution b(r): b = tan-1 [ Vo / (wr) ] • Says nothing about blade planform Vo Relative wind W1 b Rotational wind,w r Vo J. Philip Barnes www.HowFliesTheAlbatross.com

  9. Propeller blade - comprehensive velocity diagram • Non-rotational (axial) inflow • Axial velocity locally conserved • Finalswirl imparted suddenly • Helical wake anchored at c/4 • Wake ~ aligned with chordline • Wake-induced velocity (Vi) • Glauert: 2Viq at "rotor out" • Absolute velocity (V) increased • Relative wind (W) decreased • Immediate static pressure rise W2 Blade section Looking outboard Blade at 3 o’clock Helical wake vortex sheet w r - 2Viq V1 Chord line V2 b Axial wind Vix V1  Vo+Vix Vi Viq Glauert: consistent physics & geometry Vortex wake ~ aligned with chord line Betz cond. (wake helix), prop or turbine, with or without rotor loading, provided: r tan b= const. and z=0 (sym. sections) f Zero-lift line Rotational wind Wq w r - Viq z Relative wind W1 a V1 J. Philip Barnes www.HowFliesTheAlbatross.com

  10. Windprop Blade Angle and Operational Mode b L b b v v v w r -L w r w w r w w • Symmetrical sections and r tanb = R tanbtip Turbine Propeller Pinwheel • Pinwheeling: Zero angle of attack, root-to-tip • - No thrust, no torque, small drag • Efficient prop: Rotate ~115% of “pinwheel RPM,” or fly at 87% of “pinwheel airspeed” • Efficient turbine: Rotate ~ 87% of “pinwheel RPM,” or fly at 115% of “pinwheel airspeed” Define: “Speed ratio,” s v / vpinwheel = v / [ wR tanbtip ] Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  11. o o b b = 14 = 30 Low-RPM8 Blades, tip tip 1.0 Efficiency 0.8 c c l_min l_max Blades_btip 2_14o 8_30o 0.6 h Propeller f v / (t w) Turbine t w / (f v) 0.4 0.2 Speed Ratio, s ≡ v / (w R tan btip) 0.0 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.0 0.9 Propeller ~ climb Force Coefficient, F ≡ f/(qpR2) 0.8 High-RPM2 Blades, B=8 0.7 B=2 0.6 0.5 0.4 Propeller ~ cruise 0.3 F Sym. Sections 0.2 b b tan R r = tan tip Max efficiency 0.30 0.1 Blade Geometry Regeneration Max capacity 0.25 0.0 Regeneration Pinwheel 0.20 R Chord, c/ -0.1 0.15 F= -0.011 @ B=2 Thickness 2 -0.2 0.10 F= -0.008 @ B=8 8 hub -0.3 0.05 Speed Ratio, s≡ v / (w R tan btip) R r / -0.4 0.00 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 0.00 0.25 0.50 0.75 1.00 Windprop Efficiency and Thrust • Comparable efficiency by mode • Eight blades quieter than two • Climb power ~ 7x cruise power Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  12. Presentation Contents • Regen. elec. flight: Origin & Introduction • Dual-role machines: • Propeller and wind turbine • DC motor-generator • Brushless motor-generator • Integration: • Inverter-rectifier • DC boost converter • "Chop" Vs. "Boost" architecture • “Regenosoar” aircraft concept • Summary & Look Ahead

  13. Motor-generator Principles t Electromotive force, e = potential energy / charge = work / charge, (Fp / q) L = 2 N w (D/2) B L e = NDBL w ≡ k w (+) Charge (q) with velocity, V in magnetic field of strength, B: Force vector, F = q V x B L N turns k = "EMF constant" B w Fq e i i Fp Torque, t = 2N (D/2) B (dx/dt) dq = 2N (D/2) B (dq/dt) dx t = NDBiL = NDBL i = k i vi B vq E t w = e i Both modes t Motoring N turns w Fq e i i Fp vi B Change to generator mode: Same direction, rotation, w Same sign for EMF, e Sign change of torque, t Sign change of current, i vq E Generating Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  14. System Motoring and Regeneration Efficiencies Typical controller pulse-width modulation (PWM) of duty cycle (d) and efficiency h ≈ d 0.25 (*) Rt System total resistance em=kw t eb w Torque Motor Regen i • "Ideal system efficiency" ignoring controller and all losses • system motor ≈ t w/(eb i) ≈ emi / (eb i) = em/ eb = k w / eb • system regen ≈ ebi / (tw) ≈ eb i / (emi) = eb / em=eb / (k w) (*) AiAA 2010-483, Lundstrom, p.8 Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  15. Motor-generator & Battery ~ Performance Envelope and Data 100% Duty Cycle eb /(kw) THEO. EFFICIENCY, kw/eb CURRENT GROUP, i Rt / eb TORQUE GROUP, t Rt / (k eb) REGENERATION LMC "generator curve" 48V / 3,600 RPM k = 0.16 N-m/A Rt = 0.041 Ohm LMCLTD.net MOTORING EEMCO 427D100 24V / 15,000 RPM k = 0.015 N-m/A Rt = 0.075 Ohm Windprop synergy i t Phil Barnes Apr-08-2011 Trends match theory Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  16. Presentation Contents • Regen. elec. flight: Origin & Introduction • Dual-role machines: • Propeller and wind turbine • DC motor-generator • Brushless motor-generator • Integration: • Inverter-rectifier • DC boost converter • "Chop" Vs. "Boost" architecture • “Regenosoar” aircraft concept • Summary & Look Ahead

  17. Brushless "DC" Motor-generator ~ "Y" configuration Brushed Vs. Brushless Virtues, features, & limits Brushed: Theory foundation tw=ei ; e=kw ; t=ki 2-wire interface Simplified control Brush maintenance ~120V limit (arcing) Low-speed cogging N S Brushless: Inverter required 3-wire interface >1000V capable Minimal cogging Same as brushed: tw=ei ; e=kw ; t=ki Regenerative Electric-powered Flight J. Philip Barnes

  18. Brushless motor-gen. & inverter: Equivalent DC machine t w = emi motor or gen Equivalent DC machine Inverter- Rectifier t M-G eb w i Brushless machine with inverter/rectifier as a system follows brushed DC machine principles: tw = emi ; em = kw ; t = k i Both systems have 2-wire interface with the power circuit Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  19. Presentation Contents • Regen. elec. flight: Origin & Introduction • Dual-role machines: • Propeller and wind turbine • DC motor-generator • Brushless motor-generator • Integration: • Inverter-rectifier • DC boost converter • "Chop" Vs. "Boost" architecture • “Regenosoar” aircraft concept • Summary & Look Ahead

  20. Transistor and flyback diode • "High-tech, high-power light switch" • Inverter commutation & DCBC boost adjust • Lo-freq. (20-100 Hz) for commutation • Hi-freq. (>10 kHz) pulse-width-mod (PWM) • VGE (say 12 V) sets the collector current IC • Collector voltage VCE(say 600 V) sets power • Flyback diode for switch energy dissipation • iGBT & diode unidirectional (via arrows) • Transistor ~ 2V loss ; Diode ~ 0.7V loss IC iGBT MOSFET VCE Collector Flyback Diode Gate VGE Emitter Gate voltage (VGE) "opens the valve" Gate voltage, VGE Gate voltage, VGE Regenerative Electric-powered Flight J. Philip Barnes

  21. Inverter-rectifier ("inverter" for motoring mode) VB 1 1 2 2 3 3 VB • Switch pairs: one "upper" & one "lower" • Avoid short circuit: Always "diagonalize" • Each phase, per cycle: • - Connect to battery voltage 120o • - Connect to ground 120o • - "Float" twice for 60o each float • Inverter converts 2-wire DC to 3-wire "AC" • Commutation toggles each phase 0-to-VB Regenerative Electric-powered Flight J. Philip Barnes

  22. DC-to-AC conversion ~ "inverter" commutation waveforms AC basis "Dead time" avoids short circuit Inverter Regenerative Electric-powered Flight J. Philip Barnes

  23. Inverter-rectifier ("inverter" for motoring mode) ~ Snapshots VB VB VB VB 1 1 1 1 1 1 1 VB VB VB 1 2 2 2 2 2 2 VB 2 2 3 3 3 3 3 3 3 3 "Upper" switch pairs diagonally with a lower switch Two phases are operating; one phase is "floating" Regenerative Electric-powered Flight J. Philip Barnes

  24. Inverter-rectifier ("rectifier" for generating mode) - iGBT Snapshot E1 - E3 > EB 1 1 2 2 EB Diodes provide "free" regen! 3 3 Current to battery! • Rectifier converts 3-wire AC to 2-wire DC • Battery is recharged via flyback diodes • Diodes enable only two phases at once • Commutation "ignored" (unidirect. iGBT) Regenerative Electric-powered Flight J. Philip Barnes

  25. Inverter-rectifier ("rectifier" for generating mode) - MOSFET E1 - E3 > EB 1 1 2 2 3 3 EB Current to battery • Rectifier converts 3-wire AC to 2-wire DC • Charge battery via MOSFETs & flyback diodes • Bi-directional: Comm. MOSFET assists diode Regenerative Electric-powered Flight J. Philip Barnes

  26. Pulse-width modulation: Energy loss due to "chopping" • Commutation voltage cycle ion iav • Comm. + PWM superimposed || dt | t | • At a given voltage, cruise current ≈ 15% of climb or accel current • Superimposed on commutation: PWM "chopping" at part load • Typical switching frequency (f) for chopping ≈ 20 kHz (inaudible) • Reduce the duty cycle (d) to reduce average current (iav = d ion) • Energy is lost (iGBT & diode) with each on/off switching cycle • Per-iGBT switching energy loss (Sp) ≈ 20 mJ per switch cycle • To minimize chopping losses, apply PWM only to "upper" phase • Switch power loss = f Sp = 0.4-1.0 kW = 13-05% @ 3-20 kW/phase Remove PWM from commutation; Incorporate DC boost converter Regenerative Electric-powered Flight J. Philip Barnes

  27. Presentation Contents • Regen. elec. flight: Origin & Introduction • Dual-role machines: • Propeller and wind turbine • DC motor-generator • Brushless motor-generator • Integration: • Inverter-rectifier • DC boost converter • "Chop" Vs. "Boost" architecture • “Regenosoar” aircraft concept • Summary & Look Ahead

  28. DC boost converter enables efficient motoring & regen VM L M-G brushed or brushless with inv. VB C iGBT PWM Boost battery voltage to efficiently drive the M-G as a motor Boost motor-generator EMF to efficiently recharge the battery • DCBC: Key enabler, efficient bi-directional power management • Only the motoring mode is shown in the introductory graphic above • “Boosts” DC voltage ~ 0-500 % with minor input/output ripple • Power conservation: doubling the voltage halves the current • Enables reduced battery totem pole length, i.e. Toyota Prius* • DC voltage gain or “boost” is controlled by PWM “duty cycle” • PWM used for DCBC gate current, not motor-gen main current Regenerative Electric-powered Flight J. Philip Barnes

  29. DC boost converter – Equivalent circuits VM L M-G brushed or brushless with inv. VB C iGBT PWM iGBT on iGBT off iB iB VM VM iM iM L diB /dt L diB /dt C dVM/dt VB VB C dVM/dt dt |--t--| iGBT gate PWM d≡ duty cycle ; t≡ period Regenerative Electric-powered Flight J. Philip Barnes

  30. DC boost converter – Voltage gain & conversion efficiency Time segment 1: iGBT on for Dt = dt Segment 2: iGBT off for Dt = (1-d)t [a] Voltage loop: VB - L DiB1 /(dt) = 0 [b] VB - L DiB2 /[(1-d)t] = VM iB iB VM VM [c] Output current: iM - C DVM1 /(dt) = 0 [d] iB - C DVM2 /[(1-d)t] = iM iM iM L DiB2 /[(1-d)t] L DiB1 /(dt) [e] PWM cycle: DiB1 + DiB2 = 0 [f] DVM1 + DVM2 = 0 C DVM1/(dt) C DVM2 /[(1-d)t] [g] Combine [a,b,e]: VM/VB = 1/(1-d) VB [h] via [c,d,f]: iM/iB = 1-d VB Combine [g,h]: h ≡iMVM /(iBVB) = 1 iGBT gate PWM dt |--t--| • Voltage gain is set by duty cycle (d) • Efficiency = 1 (resistance neglected) d≡ duty cycle ; t≡ period Regenerative Electric-powered Flight J. Philip Barnes

  31. DC boost converter - efficiency and regen application 233 Vdc in Regen Cruise Climb Regen 5 10 15 20 kW Motor "Evaluation of 2004 Toyota Prius," Oakridge National Lab, U.S. Dept. of Energy L VB M-G C iGBT PWM • DC boost converter integrates windprop and motor-generator • Adjust PWM duty cycle to hold voltage gain as RPM decreases • Efficient bi-directional power over a wide operating range Regenerative Electric-powered Flight J. Philip Barnes

  32. Voltage Map - Motoring and Regen with DC boost converter Batt, boost factor 3.0 Voltage Climb Batt: 600V M-G: 400V M-G, boost = 2.0 M-G, boost = 1.5 Batt, boost factor 2.0 Cruise Max Regen M-G: 260V Batt: 200V Motor-gen EMF, no boost Opt. Regen Battery, no boost • Boost the battery for motoring • Boost the M-G for regeneration %RPM Regenerative Electric-powered Flight J. Philip Barnes

  33. Presentation Contents • Regen. elec. flight: Origin & Introduction • Dual-role machines: • Propeller and wind turbine • DC motor-generator • Brushless motor-generator • Integration: • Inverter-rectifier • DC boost converter • "Chop" Vs. "Boost" architecture • “Regenosoar” aircraft concept • Summary & Look Ahead

  34. Architectures compared i Inverter- Rectifier eb M-G PWM superimposed on commutation "Chopper" architecture PWM main current chop Cruise: high chopping loss Regen: none or inefficient PWM w w t t Commutation 12V i Inverter- Rectifier DC Boost Converter 2-way boost eb M-G "Boost" architecture PWM sets DCBC boost Efficient motor & regen Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  35. Presentation Contents • Regen. elec. flight: Origin & Introduction • Dual-role machines: • Propeller and wind turbine • DC motor-generator • Brushless motor-generator • Integration: • Inverter-rectifier • DC boost converter • "Chop" Vs. "Boost" architecture • “Regenosoar” aircraft concept • Summary & Look Ahead

  36. Regenosoar - Features and Design Rationale Regen parked in the wind With safety perimeter Counter rotors Symmetric flow Zero net torque 8-blade rotors Low RPM, quiet, Low vibration Low tip Mach Ground handling No assistance req'd Winglet tip wheels Pod-air-cooled MG & PE Compact power train Battery, motor-gen and powertrain Pusher Config. Symmetry upstream Max. laminar flow Regenerative Electric-powered Flight J. Philip Barnes

  37. Min. Sink Section Windprop System Removed Max L/D Section and Vehicle Drag Polars "Clean configuration" ~ Windprop System Removed 1.50 Lift Coefficient, c or c L l 1.25 1.00 "Clean" aircraft 0.75 0.50 0.25 Drag Coefficient, c or c D d 0.00 0.00 0.01 0.02 0.03 0.04 0.05 Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  38. Steady-state load factor (nn) ~ “g-load” and turn radius L= nn w v nn L/ w = cosg / cosf * Glide: nn 1 Turn: nn 1 / cosf f g * SAE 2004-01-3088 EQN 5.2, dg/dt = 0 w Load Factor and Bank Angle Load Factor and Turn Radius 400 1.05 50 350 n Bank Angle Turn Radius, m n 300 fo 40 1.1 250 r = v2(cosg) / (g tanf) 30 200 1.2 f = cos-1[(cosg)/nn)] Thermaling 150 20 1.4 1.6 100 10 50 Load Factor, nn Airspeed, v_km/h 0 0 0 20 40 60 80 100 120 140 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  39. Load Factor and “Clean” Sink Rate 0.0 dz/dt ~m/s Sea level Max L/D 2 25 kg / m Min Sink A = 16 -0.5 1.0 -1.0 1.2 1.4 -1.5 1.6 g-Load, nn -2.0 Airspeed, v ~ km/h -2.5 50 60 70 80 90 100 110 120 130 140 150 cL= nn w / (qs) “Clean” REGEN Windprop removed Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  40. Steady-state climb or descent ~ New Formulation, New Insight Derive steady-climb Equation f v L= nn w T-D g g w Note:nn= cosg /cosf * cL= nn w / (qs) • Glider, soaring bird, or "clean" regen • T/D=0 (no thrust) • Sink rate (-dz/dt) = nn(D/L)v • With or without propulsion system • Sink increases with g-load (nn) • D/L also increases with (nn) • Sink increases with airspeed (v) • Regen operating mode T/D • climb 6.3 • cruise = 1.0 • pinwheel glide -0.1 • efficient regen (thermal) -0.4 • capacity regen (descent) -1.0 * SAE 2004-01-3088 EQN 5.2, dg/dt = 0 Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  41. Regenerative Electric Flight Equation and Implications • Regen must have • Updraft • High L/D, Low sink • High efficiency • Prop & turbine • Energy storage “Clean” sink rate Windprop Effect Updraft • e ≡ “Exchange Ratio,” as applicable: • turbine system efficiency ~71% • 1 / propeller system efficiency • 0 for pinwheeling (no exchange) “Total Climb” “Total Sink”

  42. Thermal Updraft Contours Elevation, zo ~ m • 1oC warmer-air column • 20-minute lifetime • ~ solar power x 10 U ~ m/s 1 2 3 Total Energy = Kinetic + Potential 4 Total Energy = Kinetic + Potential + Stored Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  43. Climb and Regeneration in the Thermal (minimum-sink airspeed) Elevation, m Elevation, m Climb rate Contours Energy rate Contours Optimum Elevation, m Equilibrium Regeneration Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  44. Regenerative Electric Flight Equation Applied for RegenoSoar 0.82 0.88 Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

  45. Presentation Contents • Regen. elec. flight: Origin & Introduction • Dual-role machines: • Propeller and wind turbine • DC motor-generator • Brushless motor-generator • Integration: • Inverter-rectifier • DC boost converter • "Chop" Vs. "Boost" architecture • “Regenosoar” aircraft concept • Summary & Look Ahead

  46. Regenerative Electric-powered Flight • Windprop: 8 blades spin slow, quiet, & efficient • DC & BLDC machines: EMF proportional to RPM • M-G & battery verify theoretical efficiency trends • Synergy of windprop & MG: Efficiency Vs. RPM - Optimum “speed ratios” ~ 85% & 115% by mode • Popular "chopper" control: inefficient at cruise • DC boost converter: efficient climb, cruise, regen • Regen applications: • Thermal, ridge, wave, final descent, .... • UAV fleet, storm rider, earth observer, .... • Give up 2% prop efficiency w/symmetric sections to gain perhaps 5-15% range and/or flying time VM M-G iGBT A "regen" is coming soon to an airport near you! Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

More Related