model s – a game changer of electric vehicle
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Model S – A Game Changer of Electric Vehicle. Yih-Charng Deng ( 鄧益常 ) Technical Fellow, Crash Safety, Tesla Motors Weilin Chang ( 張維麟 ) Engineering Manager, Power & Vehicle Electronics, Tesla Motors. Transportation Issues Facing the Human Race. - PowerPoint PPT PresentationTRANSCRIPT
Model S – A Game Changer of Electric VehicleYih-Charng Deng (鄧益常 )
Technical Fellow, Crash Safety, Tesla MotorsWeilin Chang (張維麟 )
Engineering Manager, Power & Vehicle Electronics, Tesla Motors
Transportation Issues Facing the Human Race
• Global automobile population > 1 billion in 2010 (Ward’s Auto report)
• Will double by 2030• Not sustainable (petroleum & capacity for production,
greenhouse gases emission)• Sperling & Gordon, 2009, Two Billion Cars: Driving Toward
Sustainability– Vehicle transformation (hybrid, electric, etc.)– Fuel transformation (biofuel, hydrogen, etc.)– Mobility transformation (rapid mass transit,
telecommunication, etc.)
History of EV
• In 1900: 40% steam, 38% electricity, 22% gasoline• In 1920s, IC engine vehicles started to dominate• Air pollution problems in major US cities• 1990 Clean Air Resources Board (CARB) of CA &
Zero-Emission Vehicle (ZEV) mandate• EV1 from GM• ZEV abolished in 2003, EV1 program terminated
by GM
Fuel Economy Drive
• 1975 – Corporate Average Fuel Economy (CAFÉ)
• 2007 – Energy Independence and Security Act (EISA), 35 mpg by 2020
• 2009 New Fuel Economy Proposal – 35.5 mpg by 2016
• 2011 US Government Agreement w/ 13 Car Manufacturers – 54.5 mpg by MY2025
• Hybrid vehicles and new wave of EV
EV Advantages/Disadvantage
• Higher efficiency (80%), 3 times that of IC engine• Energy chain (source to wheels) – EV is 10-30%
more efficient (expect to increase)• Can use clean energy source at power plants
(solar, wind, hydro)• Current EV’s < 100 miles range• 2012 Model S from Tesla Motors
– Over 300 miles range– 0 to 60 mph in 4.4 sec.
Electric Vehicle Powertrain
Type of EV Electric Propulsion System
Energy Storage System
(Primary)
Energy Storage System
(Secondary)Electrical Charge Vehicle Model
Battery EV All Electric Motor Battery Pack External Power
Source & Regenerative Brake
Tesla Roadster, Model S, Nissan
Leaf
Fuel Cell EV All Electric Motor Fuel Cell
Extended Range EV Hybrid
Motor (ICE as
generator)Battery Pack Gasoline Tank for
Generator
External Power Source, Regenerative
Brake & Generator (ICE)
GM Volt
Plug in EV Hybrid Motor & ICE Gasoline Tank Battery PackExternal Power
Source & Regenerative Brake
Fisker Karma, Toyota Plugin
Prius
Hybrid EV Hybrid Motor & ICE Gasoline Tank Battery Pack Regenerative Brake Toyota Prius
EV Energy EfficiencyElectric Vehicle Efficiency
Internal Combustion Vehicle Efficiency
Hybrids and Plug-In Hybrid Vehicle Efficiency
All Electric Powertrain
• Energy Storage System (Battery Pack)
• Propulsion System:– Motor– Gearbox– Inverter
• Charger
Battery Design • Cell:
– Cell selection – Energy & power density– Cycle and calendar life
• Module:– Safety protection technology (open, short & propagation)– Voltage balancing– Package density– Isolation and thermal management
• Battery Pack:– Safety protection circuit– Lightweight & durability– Design for quick swap
Battery Cell Form Factor• Cylindrical Cell:
– Good cycling ability, mechanical stability, economical for manufacturing
– Heavy and relative low package density• Prismatic Cell:
– Optimal use of space by using layered approach, improving space utilization, and allowing flexible design to achieve higher package density, the metallic housing providing mechanical stability
– More expensive, less efficient in thermal management, shorter cycle life
• Pouch Cell:– Simple, flexible and lightweight solution to
battery design, highest package efficiency, cost-effective for manufacturing
– Swelling factor, shortest cycle life and less durable
Cell Chemistry
Why Lithium-ion
• Advantages– Today’s lithium-ion cells have the highest density w/ a good
balance of power density– Relatively low self-discharge, less than half that of NiCd and
NiMH– Low maintenance, no periodic discharge needed– No memory effect
• Challenges– Requires protection circuit to limit voltage and current– Subjects to aging, even if not in use – Transportation regulations when shipping in larger quantities– Higher cost
Lithium-Based Battery ComparisonSpecifications
Li-cobalt Li-manganese Li-phosphate NMCLiCoO2 (LCO) LiMn2O4 (LMO) LiFePO4 (LFP) LiNiMnCoO2
Voltage 3.60V 3.80V 3.30V 3.60/3.70VCharge limit 4.20V 4.20V 3.60V 4.20V
Cycle life2 500–1,000 500–1,000 1,000–2,000 1,000–2,000
Operating temperature Average Average Good Good
Specific energy 150–190Wh/kg 100–135Wh/kg 90–120Wh/kg 140-180Wh/kg
Specific power 1C 10C, 40C pulse 35C continuous 10C
Safety Average. Requires protection circuit and cell balancing of
multi cell pack. Requirements for small formats with 1 or 2 cells can be relaxed
Very safe, needs cell balancing and V protection.
Safer than Li-cobalt. Needs cell balancing and protection.
Thermal. runaway3 150°C 250°C 270°C 210°C
(302°F) (482°F) (518°F) (410°F)
Cost Raw material high Moli Energy, NEC Hitachi, Samsung High High
In use since 1994 1996 1999 2003
Researchers, manufacturers Sony, Sanyo, GS Yuasa, LG Chem Samsung Hitachi,
Toshiba
Hitachi, Samsung, Sanyo, GS Yuasa, LG Chem, Toshiba A123, Valence, GS Yuasa, BYD,
JCI/Saft, LishenSony, Sanyo, LG Chem, GS Yuasa, Hitachi Samsung
Moli Energy, NEC
Notes Very high specific energy,
limited power; cell phones, laptops
High power, good to high specific energy; power tools,
medical, EVs
High power, average
Very high specific energy, high power; tools, medical, EVsspecific energy, elevated self-
discharge
Model S Battery
• Equipped with over 7000 lithium-ion 18650 cells to provide up to 85kWh total energy capacity
• Active liquid cooling/heating thermal management system • Total weight about 600kg and located underneath the floor,
resulting in low center of gravity for high resistance to rollover and excellent vehicle handling
• Model S achieves 320 miles range based on EPA-2 cycle procedure
• Touchsafe quick disconnect for battery replacement or maintenance
• Multi-layers of safety protection features from cell, module to pack design
• Capable of supercharge (high current charging)• 8 years, unlimited miles warranty
Battery Pack Options of Model S
Factors Influence Range
Range vs. Speed
• Model S Cd = 0.24• EPA 2-cycle: 320 miles• EPA 5-cycle: 265 miles• New record for EV
Propulsion System
• Rear wheel drive propulsion system to provide better acceleration, road handling and no torque steering
• Fully integrated system (motor, gearbox and inverter) to provide world record power density and reduce transmission power lose between sub-systems to increase power efficiency
• Liquid cooling system for thermal management• Significantly less moving parts compared
with ICE resulting in simplicity, reliability, low material and operation cost
• IP6K9K ingress protection and IP8X under wading line depth
• Communicate with vehicle through CAN and generate desired torque based on paddle position and inputs from other modules
• Three-Phase, four- poles AC induction motor• Why AC motor (vs. DC brushless motor):
– Cost, no rare-earth metal for permanent magnets– Efficiency, adjustable magnet field strength
• Performance– Max torque: 600 Nm (443 lb-ft) during 0-5100 rpm – Max power: 416 hp (310 kW) during 5K-8.6K rpm– Top speed: 1600 rpm (130 mph)– Efficiency: Over 90%
Propulsion System – Motor
Torque Speed and Power Curve
Vehicle Metrics
0
50
100
150
200
250
300
350
400
450
0 20 40 60 80 100 120 140
MPH
Pow
er (k
W) /
Tor
que
(Nm
)
Pmax Mechanical
TaumaxElectrical
Pmax inflection point.
Top Speed
Continuous Power
Propulsion System – Gearbox
• Single speed, oil-cooled, open-differential transaxle gearbox• Fixed gear reduction ratio 9.73 to optimize top speed and
range• No transmission and clutch to reduce system complexity
and cost• Electrically actuated park brake• Design challenges
– High motor rpm– Thermal management– High power and torque– Durability
Propulsion System - Inverter
• Paralleling discrete IGBT’s forming half bridge power stage to convert DC to 3 phase AC
• Capable of converting AC back to DC to charge battery during regenerative brake
• Rated at 450A rms continuous current• Digital controller generating PWM to control switch• Coprocessor to ensure no misinterpretation of
accelerator paddle position while generating torque• Continuously monitoring inputs from vehicle and other
modules to determine current needed for desired torque• Several layers of safety features, hardware & software
Motor Control Algorithm
• Vector control (also called FOC) is a variable frequency drive control algorithm to control speed and torque of motor.
• Vector control outperforms other motor control algorithm (such as Scalar and DTC) because the non-constant vehicle speed and quick response time requirements in real driving situation.
• Both direct and Indirect FOC to calculate rotor flux position
• Produce desirable torque through flux control and torque-producing current
• Commercial DSP available for vector motor control (Clarke and Park transformation)
Vector Control Block Diagram
Onboard Charger• Each box is capable of 10KW charging, up to 31 miles per hour
of charge for Model S• Option to add 2nd charger in parallel to increase to 20kW
charging capacity (62 miles/hour)• Single phase, acceptable voltage range from 85-265V at
frequency 45-65Hz• Trickle charge if power source voltage is greater than battery
voltage• Peak charger efficiency of 92%• Maximum charge current at normal condition
– 110V: 20A from power source– 240V: 40A from single phase power source
• Program charging schedule through vehicle touch screen and check charging status remotely
• Universal Mobile Connector:– 110V, 240V and J1772 public charging station adaptors
are standard to ensure compatibility to different electrical outlets through different regions or countries.
– GFCI protection– Communicate charging status and fault condition
through indicator light– NEMA 4 environment sealed enclosure for outdoor
usage• High Power Wall Connector:
– Wall-mounted charger to provide up to 20kW charging capacity
– Enclosure design meets NEMA 3R for environmental protection
– Draw up to 80A from electrical outlet during charge– GFCI protection– Communicate charging status and fault condition
through indicator light• Supercharger:
– Dedicated industrial graded high speed charge station– Charge half the battery (85kWh) in 30 minutes
Charging Infrastructure
Powertrain Components from Taiwan
Existing Projects:• Roadster & OEM Programs:
– PEM, Charger, stator, rotor, motor shaft …• Model S Components:
– Motor steel laminations, gears …Taiwan Industry Strengths:• Power and vehicle electronics• Motor & gears• Machining, sheet metal & die casting parts
Other Salient Features – Body
• Lightweight aluminum materials for maximum mass savings• Double octagon rails for high energy absorption in crash• High strength steel used in the B-pillars and bumpers• Superb side impact and rollover protection• Structural reinforcement for rear impact protection
Chassis
• Double wishbone, virtual steer axis front suspension and independent multi-link rear suspension
• Optional air suspension
Edmunds INSIDE LINE
Interior
• 17” Capacitive Touchscreen• Optional all-glass panoramic roof
Safety
• 8 airbags• Retractor pretensioners• Load limiters• 5 point belt systems for the optional 3rd row
child seats• Sensors to trigger high voltage battery cut-off• Extensive CAE in the design and development
phases
Automobile Magazine’s 2013 Automobile of the Year Testing 10/9/12:Model S out-dragged BMW M5 (560 hp, 501 lb-ft torque) in 0-100 mph race
Compared with Other Cars
Motor Trend 8/27/12
Tesla Supercharger Network
Tesla Supercharger Network
• 6 locations unveiled on 9/25/12
• Solar carport systems, free charge for Model S owners indefinitely
• Slight net positive power transfer back to the electricity grid
• More supercharger stations in the US, Europe and Asia in 2013
Concluding Remarks
• Team dedication• Relentless pursuit of excellence• Open working environment• 2012 production all reserved• Extremely positive feedback from customers
and car critics (WSJ, USA Today, Motor Trend, 2013 Car of the Year – Yahoo Autos, Automobile Magazine)
• A sea change of automotive landscape
THANK YOU