high efficiency electric vehicle powertrain · – high motor speeds required with single speed...
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DATE:
High Efficiency Electric Vehicle Powertrain Alex Tylee-Birdsall Drive System Design FPC 2014
20th February 2014
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How to get high efficiency
Main issues with current single speed EV powertrain systems:
– High motor speeds required with single speed systems to get vehicle speed range (Vmax)
– High motor speed effects of speed related loss: bearings, gears, windage, seals
– Reliance on field weakening to get high speeds
– High losses in power electronics – Difficult balance between vehicle launch and
Vmax requirements
Solution? MUTLI-SPEED TRANSMISSION
Where are the issues?
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System Efficiency
Powertrain Efficiency Map
>91% Efficiency
1st Gear 2nd Gear 3rd Gear
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Background
• The challenge introduced by a multispeed system…
… IT NEEDS TO SHIFT!! – “POWERSHIFT”
Why the novel shift system?
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Concept Definition
• DSD considerations for EV shift system:
Shift system consideration
Shift Quality
Drag
In Gear Energy
Cost
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Concept Definition
• DSD considerations for EV shift system:
Shift system consideration
Shift Quality
Drag
In Gear Energy
Cost
SEAMLESS
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Concept Definition
• DSD considerations for EV shift system:
Shift system consideration
Shift Quality
Drag
In Gear Energy
Cost CLOSE TO MANUAL
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Concept Definition
• DSD considerations for EV shift system:
Shift system consideration
Shift Quality
Drag
In Gear Energy
Cost
NO ENERGY
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Concept Definition
• DSD considerations for EV shift system:
Shift system consideration
Shift Quality
Drag
In Gear Energy
Cost ESTABLISHED TECHNOLOGY
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Concept Definition
• Review of available technologies • Friction: smooth torque control • Mechanical lock: reduced energy requirements
Technology research
Power Shift Drag In Gear Energy Cost
Clutches/brakes Synchronisers Dog Clutches One way clutches ? Const. Load Synch. * ? MSYS
* DSD - CTI 2009: “Next Steps In Automated Manual Transmission Technology”
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Concept Definition
"Separation of synchroniser functions”
DSD solution
ACT 1
1st
ACT 2 ACT 3
3rd 2nd
CONE CLUTCH “FRICTION”
DOG CLUTCH “LOCK”
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Hardware
MSYS 3D
3D view
Cone Dog Gear
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Hardware
• MSYS input shaft
Input Shaft 2D
1st CONES
Act#3 Act#2
Act#1
1st 2nd 3rd
3RD CONES
2ND CONES
2ND DOG
3RD DOG
1ST DOG
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Shift Control MSYS generic power shift
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Shift Control
• STEP1: 1st Gear DOG Engaged
Shift Sequence Explained
ACT 1
1st
ACT 2 ACT 3
3rd 2nd
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Shift Control
• STEP2: Apply CLT
Shift Sequence Explained
ACT 1
1st
ACT 2 ACT 3
3rd 2nd
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Shift Control
• STEP3: Release 1st Gear DOG – Drive on CLT
Shift Sequence Explained
ACT 1
1st
ACT 2 ACT 3
3rd 2nd
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Shift Control
• STEP4: Perform CLT2CLT torque transfer
Shift Sequence Explained
ACT 1
1st
ACT 2
3rd 2nd
ACT 3
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Shift Control
• STEP5: Adjust input speed to new gear & Release 1st Gear CLT
Shift Sequence Explained
ACT 1
1st
ACT 2
3rd 2nd
ACT 3
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Shift Control
• STEP6: Engage 2nd Gear DOG
Shift Sequence Explained
ACT 1
1st
ACT 2
3rd 2nd
ACT 3
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Shift Control
• STEP7: Release 2nd Gear CLT
Shift Sequence Explained
ACT 1
1st
ACT 2
3rd 2nd
ACT 3
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Shift Control MSYS optimised power shift
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Shift Control MSYS "fast shift"
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Cooling and Lubrication
• Motor and transmission will share fluid for cooling, lubrication and hydraulics – Lubrizol developed fluid
• A single motor drives a two stage pump providing a twin path for oil flow – High Pressure - Hydraulic – Low Pressure – Cooling / Lubrication
• The transmission sump is used to cool the powertrain using cooling fins
• Large sump volume allows gears to be out of oil reducing churning losses
• Low pressure / high flow circuit flows through the motor then the transmission
Integrated Fluid System
Low Pressure Pump
High Pressure Pump
Sump Cooling Fins Pump Motor
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Powertrain Specification 100kW 3-Speed
E-Machine Type Axial Flux YASA motor
E-Machine Power 55kW continuous (100kW+ for 60s peak)
E-Machine Max Torque 200Nm @ 4000 rpm (limited by power electronic)
Transmission Ratios (3 speed)
1st - 9.93:1 2nd - 7.11:1
3rd - 5.08:1
Gear Shift Hydraulically Actuated Powershift Technology
Driveline Efficiency 98% Transmission, 95% Motor, 97% Power electronics, 91% Overall
Lubrication System Dry Sump (Light Oil Spray)
Park Lock Integrated Plunger Type with Electrical Actuation
Powertrain Weight 55kg Prototype Unit (wet) 45kg Production Intent (wet)
Installation Length 366mm Prototype Unit 320mm Production Intent
Cooling System Pump and In-built Sump Radiator
Options Output disconnect for e-AWD application 366
477
390
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Demonstrator Vehicle
0-100kph in 8.3s Max Speed on Flat: 160kph (continuous torque) Max Speed 33% Grade: 20kph (continuous torque) 55kph (peak torque) Max Speed 17% Grade: 83kph (continuous torque) 107kph (peak torque) A 33% grade can be driven in 1st & 2nd (Laden or Unladen) 1st Gear will break traction in unladen “kerb+100kg” condition
Performance Calculation
Kerb weight +100kg = 1405kg Gross vehicle weight = 1855kg
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Status
• Currently in prototype testing and development phase
• Vehicle build on going at MIRA
• Concept demonstrator vehicle available to drive Q2 2014.
Where are we today?
2011 2014 2012 2013
Prototype Design Concept Build & Test Vehicle Demo
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Development
• Torque to Pressure Curve:
Results
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Development
• Test facilities:
Facilities
TRANSMISSION SPIN RIG
COMPONENT RIG
DEMO VEHICLE
HYDRAULIC RIG
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Conclusions
• DSD has created a high efficiency and controllable power shift transmission for EV based on established technology
In one sentence
Shift Quality
Drag
In Gear Energy
Cost
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Acknowledgement
• Co-funded by the Technology Strategy Board, the UK’s innovation agency.
• DSD is grateful to the project partners:
MSYS Partners
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Contact us
Tel: +44 (0) 1926 678310 www.drivesystemdesign.com