Advanced Electric Vehicle Concepts for Designing Electric Bicycles Created for: IEEE, Rock River Valley Section Rockford, IL by Rakesh k Dhawan Electric Motion Systems, LLC 45150 Business Court, Suite 300 Dulles, VA 20166 October 2, 2008
E+ Advantages Powerful
• •
1000 & 750 Watt Motors High top speed (30+ mph)
Versatile
• • • • •
Any terrain: on-road and off-road All electric, pedal, or both electric and pedal Simple to Operate / On demand power Range and speed variability Advanced technology & features
Reliable
• • •
Completely new designs by very experienced Team High quality components Testing, Testing, Testing
Safe
• •
Hub Motor & Hub Battery → Low center of gravity - Stable handling and riding NiMH Battery Chemistry
• • • •
9 Forward Riding Modes 9 Exercise Modes Cruise Control Virtually Silent & Vibration Free
Low Operating & Maintenance Costs
• • •
Minimal maintenance for electric drive train Standard maintenance for bike All electronics inside
Environmentally Responsible
• •
Silent, smooth, stylish Emission-free
Additional Features
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E+ Technology: The Basics E+ Display Unit
E+ Rack Battery (Future)
Power
D
at a
Data
P
er ow
Data
E+ Hub Battery
E+ Hub Motor
Power
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E+ Motor and Battery
Electric Motor in Rear Wheel
Rechargeable Battery in Front Wheel
Hub HubMounted MountedBattery Batteryand andMotor, Motor,Gearless GearlessDirect Direct Drive, Low Center Gravity, High Stability, Drive, Low Center Gravity, High Stability,Silent Silent © Electric Motion Systems 2008. All Rights Reserved
+Que: User Interface E Brake Switches • In both brake levers • Enable regenerative braking
E+Que: Display / Control Unit • Safe/easy access • Vehicle controller and key • Removable / System Lock Security
Thumb Throttle • Thumb type • Controls output torque of motor
Twist Grip Shifter • Controls de‐railler •9 Speeds
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E+ System Diagram E+ Display Unit
E+ Rack Battery (Future)
Power
D
at a
Data
P
er ow
Data
E+ Hub Battery
E+ Hub Motor
Power
The TheE+ E+is isan anIntelligent IntelligentSystem Systemthat thatTakes TakesCare Careof of Itself Itself––Riders RidersDo DoNot NotNeed Needto toWorry WorryAbout Aboutit. it. © Electric Motion Systems 2008. All Rights Reserved
E+QUE Technology
Integrated •Bicycle Computer •Electric Vehicle Controller •Exercise Machine
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E+ Testing for Reliability • Motor Level Testing – – – –
Continuous Power Stall Torque Heat Rise Torque‐Speed Performance
• Battery Level Testing – – – –
Over Current Short Circuit Over Temperature Discharge/Charge Performance
• System Level Testing: – Shock and Vibration – Vertical Drop – Water intrusion – battery, motor, and display separately – Daily ride tests © Electric Motion Systems 2008. All Rights Reserved
The E+ System can really take it…
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Vehicle Characteristics
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Vertical Velocity, Vz Yaw Velocity
Forward Velocity, Vx
Lateral Velocity, Vy
Roll Velocity
Pitch Velocity
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Forward Motion Analysis Moving Direction
F
mg b
c
mgfr L
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Fx Wf
Equations Mbicycle.a = ∑ Ftraction ‐ ∑ Rfriction a = dV/dt Wkinetic = 1/2. Mbicycle.V2
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Maximum Traction Force Fxmax = μ.N μ = ƒ (tire material, tire temperature, tire inflation pressure, tread geometry, road roughness, road material, road conditions etc.)
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Normal Forces Nf = Mbicycle.g. (c/L).cosθ‐ Mbicycle.a.(h/L) ‐ Mbicycle.a.(h/L).sinθ Nr = Mbicycle.g. (b/L).cosθ‐ Mbicycle.a.(h/L) + Mbicycle.a.(h/L).sinθ
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Rolling Resistance Rx = f.Mbicycle.g f = Coefficient of rolling resistance = ƒ (tire material, tire temperature, tire inflation pressure, tread geometry, road roughness, road material, road conditions etc.)
f = f0 + 3.24. fs. (V/224)2.5 [Stuttgart Model]
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Aerodynamic Drag Dx = 1/2.ρ.Af.Cd.V2 Af = Vehicle Frontal Area Ρ = Shape of the Vehicle and Air Density Cd = Aerodynamic Drag Coefficient
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Grade Climbing
mg.sinθ
mg.cosθ
mg
θ
Gx = Mbicycle.g.Sin θ Wp = Mbicycle.g.z © Electric Motion Systems 2008. All Rights Reserved
Acceleration Performance F1
F1>F2>F3 P1>P2>P3 W1>W2>W3
Constant Force F2
Constant Power
Force F3
W1, P1 W2, P2 W3, P3 Vbase
Speed
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Acceleration Performance • Maximum Acceleration is defined by maximum available force in the vehicle and tire ground contact. • The vehicle is designed to be in constant force mode followed by constant power mode. • Rated power can be reduced considerably by minimizing the constant force region thereby reducing size, weight, and cost. © Electric Motion Systems 2008. All Rights Reserved
Equations Prated = Fmax.Vbase F = Prated/V Wkinetic = ∫Ptraction.dt
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Let us Define our Vehicle
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Vehicle Parameters Vehicle Parameters Tire diameter Vehicle Weight
English 2.17 ft= 60 lbs=
SI 0.661 27.216
m kg
Number of Passengers
1
Weight per passenger
185
lbs=
83.916
kg
Total weight
245
lbs=
111.132
kg
5.0 1.00 0.014 1
ft =
2
0.46
m
Projected area Horiz drag coefficient Rolling coefficient Number of motors
2
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Performance Requirements • Top Speed = 30 mph on a flat ground with a 185 lb rider • Climb 20% grade at 10 mph for 2 miles • Range of 20+ miles at a speed of 15 mph on a flat ground • 0 to 25 mph in 10 seconds © Electric Motion Systems 2008. All Rights Reserved
Top Speed = 30 mph Total system efficiency
70%
Flat Road Acceleration Slope grade Angle of inclination Acceleration force Grade force Rolling force Drag force Total force = Accel + Drag + Rolling + Grade Speed Angular speed Total torque req'd. Output torque Output power Input power
0.00 0.0% 0.00 0 0 3.43 11.5
Gs
0.00
m/s2
deg lbs= lbs= lbs= lbs=
0 0 15 51.2
N= N= N= N=
0.0 0.0 1.6 5.2
kg kg kg kg
15 30.0 40.32 16 16 1.19 1.72
lbs= mph= rad/sec= ft-lb= ft-lb= hp= hp
67 48.00 385.0 22.0 22.0 0.887 1.267
N= km/h= rpm N-m N-m kW kW
7 13.3
kg m/s
360 0.28 17 8.5 13.6
Battery Energy Time Range
W hr hrs mins miles km
Battery Capacity 10 Ah Battery Voltage 36 V © Electric Motion Systems 2008. All Rights Current 35.19 A
Reserved
Grade Climb of 20% Total system efficiency Maximum climb Acceleration Slope grade Angle of inclination Acceleration force Grade force Rolling force Drag force Total force = Accel + Drag + Rolling + Grade Speed Angular speed Total torque req'd. Output torque Output power Input power
65%
0.00 20.0% 11.31 0 48.048 3.4 1.3
Gs
0.00
m/s2
deg lbs= lbs= lbs= lbs=
0 214 15 5.7
N= N= N= N=
0.0 21.8 1.5 0.6
kg kg kg kg
53 10.0 13.44 57 57 1.40 2.18
lbs= mph= rad/sec= ft-lb= ft-lb= hp= hp
234 16.0 128 77.5 77.5 1.042 1.603
N= km/h= rpm N-m N-m kW kW
24 4.4
kg m/s
Battery Energy Time Range
360 0.22 13 2.2 3.6
W hr hrs mins miles km
Ah Battery Capacity 10 Battery Voltage 36 V Current© Electric Motion Systems 2008. All Rights 45 A Reserved
Range = 20+ miles Total system efficiency Maximum climb Acceleration Slope grade Angle of inclination Acceleration force Grade force Rolling force Drag force Total force = Accel + Drag + Rolling + Grade Speed Angular speed Total torque req'd. Output torque Output power Input power
80%
0.00 0.0% 0.00 0 0 3.4 2.9
Gs
0.00
m/s2
deg lbs= lbs= lbs= lbs=
0 0 15 12.8
N= N= N= N=
0.0 0.0 1.6 1.3
kg kg kg kg
6 15.0 20.16 7 7 0.25 0.32
lbs= mph= rad/sec= ft-lb= ft-lb= hp= hp
28 24.0 193 9.3 9.3 0.187 0.234
N= km/h= rpm N-m N-m kW kW
3 6.7
kg m/s
360 1.54 92 23.1 36.9
Battery Energy Time Range
W hr hrs mins miles km
Ah Battery Capacity 10 Battery Voltage 36 V © Electric Motion Systems 2008. All Rights Current 6 A Reserved
Min Torque vs Speed Curve 100.00 90.00 80.00
Torque (N-m)
70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00 0
25
50
75
100
125
150
175
200
225
250
rpm
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275
300
325
350
375
400
Vehicle Performance Data Vehicle Acceleration vs Time 2.50
90.00 Drag Force (N)
Motor Torque (N-m)
Velocity (kph)
Accel (m/s^2)
80.00 2.00
70.00
1.50 50.00
40.00 1.00
A c ce lra tion (m /s
60.00
30.00
20.00
0.50
10.00
0.00
0.00 0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
Time (sec)
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Specifications • Vehicle: A bicycle which remains a bicycle after installation of propulsion components. No noise is added during operation by propulsion components
• Motor and Controller: 85Nm, 1000W, 85% Efficient, 8 kg, No Vibration, No Noise, In the spokes of a bicycle wheel
• Battery Pack: 36V, 10AHr, NiMH, 8kg, Safe, In the spokes of a bicycle wheel
• Vehicle Controller: Bicycle computer, electric vehicle controller and exercise computer in one. © Electric Motion Systems 2008. All Rights Reserved
Challenges • A Bicycle Chassis is very light. • Motor Design – 1000W • Motor with embedded controller • 36V, 10AHr Battery Pack in a hub • Battery Pack with embedded BMS © Electric Motion Systems 2008. All Rights Reserved
Motor Design
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Starting with a Clean Slate • Off the shelf motor? • Which motor technology is best suited? – Switched Reluctance Motor – Induction Motor – Brushless Permanent Magnet – Brushed DC
• What are the trade offs?
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Trade‐Offs ? SRM
IM
Brushless
Brushed DC
Vibration Free
No
Yes
Yes
Yes
Smooth Operation
No
Yes
Yes
Yes
Ease of Control
No
No
Yes
Yes
Low Maintenance
Yes
Yes
Yes
No
Constant Power Range
Yes
Yes
Yes
No
Cost
Low
Low
High
High
Efficiency
High
High
High
Low
Ease of Cooling
Low
Low
High
High
Reliability
High
High
Medium
Low
Compactness
Low
Low
High
Medium
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Motor Technology • Decisions to be made: – – – – – – – –
Geared vs. Gearless Hub vs. Chain Driven Output Power/Peak Torque Number of Magnets Number of Stator Poles Half Bridge vs. Full Bridge Sensing Scheme Location of the Motor Controller © Electric Motion Systems 2008. All Rights Reserved
Motor Parameters Characteristic
Value
Unit
Torque, Peak
85
Nm
Torque, Continuous
30
Nm
Speed, Top
450
rpm
Speed, Base
125
rpm
Voltage, Bus (nom)
36
V
Rotor Diameter
0.244
m
Stack Length
0.05
m
Air Gap
1.0
mm
Weight
8.2
Kg
© Electric Motion Systems 2008. All Rights Reserved
Good Prior Art [2003] 7‐Phase TidalForce Motor
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Good Prior Art [2003] Example Motor Design Parameters
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Example FEA Analysis
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Sources of Loss • • • • • •
Battery Internal Resistance Core Back Iron and PM ring Bearing Resistive Inverter
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Design of Power Electronics Factors which affect the design: •Motor Phase Current •Switching Frequency •Overall System Efficiency •Half‐Bridge vs. Full‐Bridge Configuration •Input ripple current
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What do we worry about? • • • • • • • • • • •
Winding Loss Power Input Power Output Temperature Rise Efficiency Battery Time Conduction Losses Range Duty Cycle Switching Loss Torque Produced per Amp © Electric Motion Systems 2008. All Rights Reserved
Example Winding Loss Plot (Torque Vs. Motor Speed with Winding Loss in Watts)
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Example Input Power Plot (Torque Vs. Motor Speed with Input Power in Watts)
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Example Output Power Plot (Torque Vs. Motor Speed with Output Power in Watts)
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Example Phase Current Plot (Torque Vs. Motor Speed with Phase Current in Amps)
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Example MOSFET Conduction Losses Plot (Torque Vs. Motor Speed with MOSFET Conduction Loss in Watts)
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Example MOSFET Switching Losses Plot (Torque Vs. Motor Speed with MOSFET Switching Loss in Watts)
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Example System Duty Cycle Plot (Torque Vs. Motor Speed with Duty Cycle in %)
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Power Electronics Architecture – Comparing Half Bridge vs. Full Bridge
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
© Electric Motion Systems 2008. All Rights Reserved
Example Ripple Current Estimation Plot for Estimating Input DC Link Capacitors
Source: Seven phase brush‐less synchronous motor with reduced inverter size, Dhawan, Soghomonian, IEEE Applied Power Electronics Conference and Exposition No19, Anaheim CA , ETATS‐UNIS (22/02/2004)
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Control Algorithm • BLDC (Trapezoidal Control) – Basic Control – Most Motors in the industry today – Chinese Kits, BionX, Crystalyte, Giant Twist, Optibike, etc.)
• Sinusoidal PWM (Scalar Control) – Semi‐Advanced Control • TidalForce Motor/Sparta Ion Motor (designed at Wavecrest Laboratories)
• SVPWM (Space Vector PWM) – Most Advanced and State of the Art Control – E+ Electric Bicycle Motor by Electric Motion Systems © Electric Motion Systems 2008. All Rights Reserved
Field Weakening/Phase Advance Control to achieve 6 to 1 Speed Advance w.r.t Base Speed
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E+ Motor Technology • Brushless permanent magnet motor – No maintenance, highly reliable, smooth operation
• Powerful: – 1000W
• No Gears: – No maintenance, no noise, highly efficient
• ‘Inverted design’: – high torque, low inertia
• All electronics inside: – Unique – much higher reliability (min wires, connectors, ‘boxes’), easy to replace if necessary
• Advanced software control: – Higher torque, speed, efficiency, and safety
• Sealed: – Against water, dirt, sand, etc. © Electric Motion Systems 2008. All Rights Reserved
E+ Motor Performance • 80Nm Torque – Extremely high – Fast acceleration – Great hill climbing ability
• 1000W max power – High Top speed
• High peak efficiency – 82% Efficiency
• 8.2kg (18lbs) – Very High torque/power density
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Battery Technology
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Battery Decisions • Battery Types – Lead Acid – NiMH – Li Ion – NiCd etc.
• Cell Shapes – D Cells – C Cells – Rectangular shapes etc. © Electric Motion Systems 2008. All Rights Reserved
Pack Design Considerations • • • • • • • • • •
Chemistry Weight Safety Power Density Operational Behavior Serviceability Maintenance Requirements Longevity Cost Load Characteristics etc. © Electric Motion Systems 2008. All Rights Reserved
Battery Management System • Regulate Charge • Regulate Discharge • Protect Cells against – Short Circuit – Over Temperature – Under Voltage
• Record Data to understand usage and behavior • Allow more than one pack to be connected in parallel © Electric Motion Systems 2008. All Rights Reserved
NiMH Battery Efficiency
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Source www.batteryuniversity.com
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E+ Battery Technology • 30 NiMH 10 Ahr D‐cells: – Safe technology
• 5‐cell modules: – Unique ‐ Battery can be easily refurbished
• All electronics inside: – Much higher reliability (min wires, connectors, ‘boxes’), easy to replace if necessary
• Advanced Battery Management System: – Uses battery to max safe limits, Protects from over discharge & abuse, Maximizes battery life
• ~ 500 charge cycles – 80% of original capacity remaining
• Sealed: – Against water, dirt, sand
© Electric Motion Systems 2008. All Rights Reserved
Vehicle Controller
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E+QUE Technology
Integrated •Bicycle Computer •Electric Vehicle Controller •Exercise Machine
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E+Que: Display Technology • Vehicle Controller and Key – Removing display disables system
• 19 different drive modes – 9 Power Modes, 9 Regen Modes, Neutral
• • • • •
Security Mode Cruise Control Speedometer Battery State of Charge Other Vehicle Data: – Odometer, Trip Odometer, Trip Timer, Battery Power (+/‐), Average Speed, Max Speed, etc.
• LED Backlight – for night riding
• Sealed: – Against water, dirt, sand, etc. © Electric Motion Systems 2008. All Rights Reserved
Inside E+ Que LCD
•Plastic Housing PCB
LCD Lens
Push Buttons
Waterproof Connectors Plastic Cover Waterproof Design © Electric Motion Systems 2008. All Rights Reserved
Questions
Email:
[email protected] Phone: Toll Free (877) 624‐5339
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