Electric Systems Configuration Denis Loo Denis.KC.Loo@Gmail.com Version 21 2.1 1
Motivation or Why Bother??? Clean and Quiet Indoor Flying Suited for smaller Aircraft & Heli s Electric Only Kits/ARFs FPV, Suitable for data logging Motor Gliders (Restarting/Stowing) Multi Rotor Applications Lower cost with smaller sizes Many Brands & Mfg of components available (Lots of choices and options) Convenience Reduced Maintenance Required Finishes need not be Fuel Proof Mass Stability Performance Stability ActivePropBraking Possible No more Dead Sticks Less Vibration Conversion kit availability 2
Constraints Flight Time 15 min (Shorter) Charging Time & Care Battery Life, Performance and Cost Environmental Temperature & Moisture Control and Propulsion Power Battery Access & Cooling Cost Trade Offs (Generators, Car Battery) Safety 3
Motor Components Battery, Capacitors Connectors, Spark Arresting EMI, CE (Electrical Noise) & Filters/Shielding Switches, Arming SafetySwitches Switches, Alarms Electronic Speed Control (ESC) Battery Elimination Circuit (BEC) or A123 E Props 4
Basic Knowledge 1 Horsepower (HP) = 745.7 Watts (W) 1 Kilowatt (kw) = 1000 W Voltage (V) Volts (V) Current (I) Amperes (A) Resistance (R) Ohms (Ω) Voltage (V) = Current x Resistance (V=I*R) Ohm s Law Power (P) = Current x Voltage (P=I*V or I 2 *R) Battery Capacity (β) = Current x Time (β=i*t) = 1A*h 1000 mah 5
Basis & Interpretation Force (N) = Mass (kg) x Acceleration (m/s 2 ) = kg*m/s 2 Work (J) = Force (N) x Distance (m) = N*m or Energy Power (W) = Work (J)/ Time (s)= N*m/s or Rate of Work Thus: 1 Watt (W) = Force of 1 N over a Distance of 1 m for 1 s 1 Joule (J) = 1 W for 1 s duration Volt (V) = Energy / Unit Charge Ampere (A) = Rate of flow Ohm (Ω) = Resistance to flow Coulomb (C) = Unit Charge = Charge carried by 1 Afor 1 s charge of approx 6.241 x 10 18 electrons (lots!) 6
How Much Power? Power Loading 180 160 140 Watt ts / lb 120 100 80 60 40 20 0 Slow Flyer or Park Flyer Trainer or Slow Flying Scale Sport Aerobatic & Fast Flying Scale Advanced Aerobatic & High Speed Lightly Loaded 3D & Ducted Fans Unlimited performance aerobatic & 3D 7
Glow Engine Output (HP) Output Power vs Displacement 25 Output (HP) Peak Power 20 15 10 5 2 Stroke 4 Stroke 0 01 0.1 1 10 100 Displacement (in 3 ) 8
Peak Power Output (kw) 18 16 14 12 10 8 6 4 2 0 Glow Engine Output (kw) Output Power vs Displacement 2 Stroke 4 Stroke 0.1 1 10 100 Displacement (in 3 ) 9
Engine Size and Output (HP) Pe eak Powe er Outpu (HP) 5 4 3 2 1 0 Output Power vs Displacement 2 StrokeGlow (O.S. EngineData) 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 Displacement (in 3 ) 10
Engine Size and Output (W) Pe eak Power Output (W) 3500 3000 2500 2000 1500 1000 500 0 Output Power vs Displacement 2 Stroke Glow 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Displacement (in 3 ) 11
Motor Selection Type (Brush, Rotor) Size & Weight Battery Configuration i (S) > Voltage Range Motor Constant (Kv = 1000 s RPM/volt) Current Rating (Sustained & Transient) Cooling Requirements Mechanical (Shaft, Mounting, Prop Adapter) 12
Motor Example Mfg: TURNIGY AerodriveXp Type: Brushless, Outrunner Model: TR35 30 B Input Voltage: 7.4V~11.1V (2~3S Li Po) KV: 1400 rpm/v within 10% # of turns: 22 Delta I MAX : 10~15A I CAP : 22A/60s Internal Resistance : 76 mω I NO LOAD @ 7V: 1.19A Dimensions: 35mm X 30mm / 1.38in X 1.18in Shaft Ø: 4mm / 0.16in Weight: 77g / 2.72oz # of poles/magnets: 14 Recommended Model Weight : 600~1300g / 21~45oz Power Equivalence :.12, 2 stroke 13
ESC Selection Type (Brushless/Brushed/Application) Current Rating (Amps) BEC Rating, Mode PWM Speed, Timing Programming Method and Options (many) Size & Weight Cooling Needs Electrical Noise and Shielding Connectors 14
ESC Selection (Typical) I CONST : 30A I BURST : 40A BEC Mode:Linear BEC: 5V / 2A Li Po Cells: 2 4 NiMH :5 12 Weight: 25g Size: 45x24x11mm User Programmable, both via controller & optional programming card. UBEC Simplicity is the key to reliability! 15
Safety Accessories Voltage Protectors Battery Alarms Arming Safety Switches Voltmeters Jeti Anti-Spark 16
Accessories ESC Programming Card USB Programming Adaptor Li-Po Charger Watt Meters Charging Bags Li-Po Cell Checker 17
Battery Options (for R/C) Type Pros Cons Alkaline Ni Cd NiMH Li Po Li FePO4 (A123) Convenient, Availability Safe, Reliable, Disposable Can be cheaper than other rechargeable types Durable, Safe Faster recharge Better Life Cycle Than Ni Cd Fewer Memory issues Higher capacity Availability, Light Weight, Popular Fast charging, Efficient Packaging High Capacity, (3.6V/cell) Charge remaining easily measured Non Rechargeable, Costly Heavier, Memory, Limited Performance Outgassing, Disposal Issues (Cadmium) Lower voltage than alkaline Heavier than Li types Lower voltage than alkaline Special Charger, Need for Balancing Voltage varies with charge, Need BEC Somewhat fragile, can be more costly Fire hazard if abused, limited cycle life g g y, y Safety and durability of Ni Cd Lighter weight than NiMH Flat Discharge (3.3v/cell) Can eliminate BEC High Current http://www.flyelectric.ukgateway.net/lithium a123.htm Limited selection, more expensive Special Charger, cylindrical cells Charge Remaining harder to measure ( t) Voltage Sag A little heavier than Li Po 18
Li Po Battery Selection Configuration: (S) = # of cells in Series Voltage (V) & Speed (P) = # of cells in Parallel Current (I) & Torque (C) = Max Continuous Discharge Max Current (I) & Peak Torque mah = Capacity & Run Time Example: 20C, 3S2P 2100 mah Battery: = 3 Cell Battery = 3.7 V/cell nominal x 3 = 11.1 V = 2 Cells in parallel = 3 x 2 = 6 Cells in pack = 2100/1000 A x 20 C x 2 P = 84A Peak Current =1C* 2100/1000 = 2.1A Max Charge Current 19
Battery Example Type: Lithium Polymer Capacity: 1800 mah Connector Type: EC2 Balancing Connector: Std 4-Pin Wire Gauge: 13 # of cells: 3 Weight: 4.0 oz (114g) Configuration: 3S Voltage (nominal): 11.1v Length: 4.05 in (103mm) Width: 1.35 in (34.5mm) Height: 0.55 in (14mm) Max Continuous Discharge: 20C Max Continuous Current: 36A 20
General Guidelines: Battery Selection Up to 50W 1s-2s Park and Indoor Flyers Up to 100W 2s-3s Park Flyers 100W-500W 3s 5lb AUW 500W-800W 4s 0.40 to 0.46 Glow Engine 800W-1000W 5s 900W-1500W 6s 0.60 to 0.90 Glow Engine More 8s-10s Specialized Large Models 21
Li Po Battery Safety Min Voltage per cell: 3.0 Min ESC Voltage Cutout: 3.0 (Hard), 3.3 (Soft) Max Charge: 1C (i.e. 1800 mah 1.8A) Lower is better Max Draw (I MAX ): Rated on battery (i.e. 30C = 1.8*30= 54A Storage @ 50 60% of Capacity (i.e. Nominal Voltage) Always connect battery last or use an arming switch Check and discard (discharge first) if mechanically upset Charge in a monitored Non-Flammable Area with approved charger Check and balance charge as required Store in non-flammable Container (i.e. Battery Safety Bag) Overheating occurs with excessive current drain or overcharging Puffing (Ballooning) may occur if overheated (capacity degraded) Battery life is finite, Capacity and I MAX will degrade with # of cycles 22
Li Po Charging Importance of balancing 23
Li Po Voltage and % Capacity Remaining 24
Battery Energy Power = I * V P = A * v (Watts) Energy = Power * Time E = W * t (Joules) Capacity of a battery β in units of ma*hr For an 3S (11.1V), 1800 mah battery: Power (for 1 hr) = 1800 / 1000 x 11.11 = 20 W for 1 hr Energy Content = 3.6 *1800 * 11.1 = 71928 J Note: Battery Capacity is degraded with frequency of excursions to I MAX! 25
Battery Output But limited by battery temp, I MAX and wire sizes! 26
Battery Life vs Output Demand 80 Curren nt (A) Outout 70 60 50 40 30 20 10 0 3600 mah 1800 mah 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Time (Min) 27
Battery Mass Mass (g) Battery 160 140 120 100 80 60 40 20 0 Li-Po Battery Mass vs Cell Capacity y = 0.0297x - 2.4149 y = 0.0247x + 1.25 y = 0.0237x + 1.0817 5-10C 10-15C15C 15-20C 0 1000 2000 3000 4000 5000 6000 Cell Capacity (mah) 28
Battery Energy Density 6000 Li-Po Cell Capacity vs Volume Capac city (ma Ah) 5000 4000 3000 2000 1000-2% y = 41.136x - 17.972-17.5% y = 40.287x - 41.279 y = 33.241x + 97.463 5-10C 10-15C 15-20C 0 0 50 100 150 Cell Volume (cm 3 ) 29
Battery Density ght (g) Wei 160 140 120 100 80 60 40 20 0 Li-Po Cell Weight vs Volume (Density) 5-10C 10-15C y = 2.1691x - 2.8829 15-20C 6% Premium y = 2.0478x - 1.4472 y = 1.9981x - 0.3891 2.5% Premium 0 20 40 60 80 Volume (cm 3 ) 30
Wire Silicone Noodle Type Popular Flexible, Hi Temp and Current Rating, Low Ω Plating to be suited to soldering (Sn, Si) Restrain to prevent fatigue due to wire movement Wire Gage vs Current Carrying Capacity 31
Connectors Polarization or Keying (non Reversible) Standards for convenience, Availability Insulation and security, Ease of installation Current trti Rating (Amps) and Wire Gage Deans popular but short circuit risk Practice Soldering Skills for good joints Use Heat shrink to prevent shorts! Anti Spark connectors can minimize arcing Arming Switches Recommended d 32
Popular Connectors EC Type JST Deans style Bullet Type XT60 HXT 33
Soldering Stuff Soldering Iron (With Cleaning Pad) Solder Flux Solder Removal Tools Soldering Jigs IPA Vise Wire Strippers Heat Gun 34
Soldering Tips Cleanliness is key Wattage of Iron and Temperature critical! Thermocouple Type Iron Faster and Stable Tip Temperature 60Sn/40Pb solder with Rosin Flux core is optimal for electronics Use suitable flux generously but avoid inhaling flux vapors Stronger solders available (not for electronics) but generally harder to use & more toxic! Avoid mixing soldering iron tips with Solder/Flux types Clean and Tin tip of soldering iron often Pre Tin components to be soldered Heat part with Iron Tip, apply solder to Part Clean completed Joint with IPA (l (Flux is corrosive) 35
Soldering Tips Lots of online Resources: http://www.talkingelectronics.com/projects/5-projects/projects13.html http://homediyelectronics.com/tutorials/solderingiseasy/?p=6 http://youtube.com/watch?v=blfxxrfrizy http://aaroncake.net/electronics/solder.htmnet/electronics/solder htm 36
Calculator Tools Many available, Some Free: Di Drive Cl Calculator: l http://www.drivecalc.de/ d / ecalc: http://www.ecalc.ch/ FlyDMA: http://brantuas.com/ezcalc/dma1.asp RC Groups Compilation: http://www.rcgroups.com/forums/showthread.php?t=606703 ETC 37
Plane: Configuration Example Ultra Stick 25E ARF Mfg Config: Baseline Option X Motor: Power 25 Power 25 Battery / mah 3S2P / 4000 4S2P / 4000 ESC 40A with BEC 40A with BEC Prop 12 x 6E 11 x 5E What would be the estimated performance benefit of a 4S battery if we want to keep the same 40A ESC? Can manually calculate, test or use online tools 38
Online Software (ecalc) Baseline 39
Online Software (ecalc) 4S Case 40
Online Software (ecalc) Plots 3S Battery Baseline : 3S2P, 4000 mah Power 25 12 x 6E New 4S Battery : 4S2P, 4000 mah Power 25 11 x 5E 41
Example Result Summary Flight Time: 9% Aircraft / Prop Speed: 15% Battery Weight: 33% Overall llaircraft Wih Weight: 14% Power Output (Max): 50% Peak Current: 10% Power/Weight Ratio: 28% Thrust/Weight Ratio: 3% 4S2P + 11x5E vs 3S2P + 12x6E 42
Bench Testing is Recommended! 43
Data: 2S 20C 7x5E APC 44
Data: 3S 35C 7x5E APC 45
Data: 2S 20C 8x4E APC 46
Data: 3S 35C 8x4E APC 47
Test Data in in amps Volts Watts Cells Rating mah KPH Mfg Type D P Imax Vmin Speed Pmax S C Capacity Speed APC SF 7 4 10.2 6.8 9624 72.4 2 20 1800 36.5 59 APC SF 7 5 11.4 6.7 9381.3 80.9 2 20 1800 44.4 71 APC SF 8 6 17.8 6 7384.3 112.2 2 20 1800 42.0 68 APC E 7 5 11.4 6.8 9399.8 79.3 2 20 1800 44.5 72 MA 7 5.5 13.4 6.5 8714.9 91.3 2 20 1800 45.4 73 APC E 8 4 12.6 65 6.5 9163.2 87.88 2 20 1800 34.7 56 MA 8 5 15.8 6.2 8116 103.2 2 20 1800 38.4 62 APC E 8 6 16.2 6.2 8217.8 110.4 2 20 1800 46.7 75 APC E 8 8 18.6 5.8 7406.4 118.9 2 20 1800 56.1 90 APC SF 7 4 19.4 11.2 14433 223.1 3 35 2100 54.7 88 APC SF 7 5 21.8 10.9 13746.6 244.6 3 35 2100 65.1 105 APC SF 8 6 37.4 10.4 10420.4 403.6 3 35 2100 59.2 95 APC E 7 5 21 11.2 14201.1 241.5 3 35 2100 67.2 108 MA 7 5.5 25.4 10.9 13017.4 281.3 3 35 2100 67.8 109 APC E 8 4 23 11.11 13669.2 264.5 3 35 2100 51.8 83 MA 8 5 29.8 10.7 11984.1 321.6 3 35 2100 56.7 91 APC E 8 6 30.6 10.7 11941.5 338.9 3 35 2100 67.8 109 APC E 8 8 35.4 10.4 10785.4 377 3 35 2100 81.7 131 48
Questions? Thank you for your interest! 49