High Efficiency Electric Vehicle Powertrain · – High motor speeds required with single speed systems to get vehicle speed range (Vmax) – High motor speed effects of speed related

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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