gkn's activeconnect all-wheel drive system · 2019-12-18 · 2 awd systems in the age of...

1

GKN's ActiveConnect

all-wheel drive system

as an energy-efficient

solution for electrified

vehicles

Christoph Schmahl | 9/10.05.2019

2

AWD Systems in the Age of ElectrificationAWD Systems in the Age of Electrification

Electrified AWD vehicles are becoming

increasingly popular

Significant growth expected in the HEV/BEV

market with East/West configuration

GKN Internal Analysis, 2018

0

5

10

15

20

25

30

35

40

2020 2025 2030

Vo

lum

e [M

un

its]

Year

AWD - HEV/BEV

AWD - conventional

AWD - conventional & HEV/BEV - North/South

East/West

AWD is realized by an electrified secondary axis, which leads

to dual motor systems with front hybridized HEV and with BEV

Example: BEV with dual motor AWD

3

Mechanical AWD System as Alternative Approach

Dual motor systems:

Two separate drive units lead to high costs,

low efficiency and mobility disadvantages

AWD systems in conventional vehicles:

Mechanical drivetrain architecture allows use

of a single source of propulsion power

Electric vehicle with mechanical AWD system

Electric vehicle with dual

motor AWD systemConventional vehicle with

mechanical AWD system

GKN’s ActiveConnect AWD system allows to

combine the best of both worlds to achieve

high vehicle efficiency

cost reduction

enhanced mobility and driving dynamics

low engineering and integration effort

4

ActiveConnect: How much AWD is needed?

Test vehicles Road profiles

AWD demand

Most of the time AWD is not required!

Road data acquisition

0%

25%

50%

75%

100%

Snowlow-µ

Countryhigh-µ

Cityhigh-µ

Autobahnhigh-µ

25%

9% 14

%

75%

91%

86

%

100%

De

ma

nd Disconnected

AWD

Active AWD

5

GKN ActiveConnect-AWD Technology

TwinsterRDU

Booster

(Single Clutch RDU)

PTU

Dog Clutch

Disc Clutches

rotating parts

parts on down time

Modular Design

Active AWD

Disconnected AWD

Increased efficiency with ActiveConnect Twinster technology improves driving performance

Throttle on –

torque bias to outer wheel

to mitigate under-steer

Throttle off –

increased locking torque

(both wheels) to mitigate

over-steer

6

TwinsterRDU

Booster

(Single Clutch RDU)

PTU

Dog Clutch

Disc Clutches

rotating parts

parts on down time

Modular Design

Active AWD

Disconnected AWD

Increased efficiency with ActiveConnect Twinster technology improves driving performance

Throttle on –

torque bias to outer wheel

to mitigate under-steer

Throttle off –

increased locking torque

(both wheels) to mitigate

over-steer

GKN ActiveConnect-AWD Technology

7

Basis Vehicles for Efficiency Simulation

• Mech. AWD with ActiveConnect

• Speed dependent disconnect

• Motor: 100 kW front

Single motor with mechanical

ActiveConnect AWDDual motor AWD (permanent) Dual motor AWD (EDD)

• Front axle with disconnect

• Efficiency optimized disconnect

• Motor: 50 kW front / 50 kW rear

• No disconnect

• Permanent AWD

• Motor: 50 kW front / 50 kW rear

Vehicle parameter:

• Mass 1885 kg

• Front area 2,6 m²

• Drag coefficient 0,33

Schematic illustration of clutch

Simulation of three different BEV AWD concepts regarding the energy consumption:

8

Growth Laws of Electric Machines

The ratio of power to efficiency of electrical machines is

determined by the so-called growth laws [1]

Scaling up an electric machine by the factor k in all it’s

linear dimensions results in an increase [1]

– of power by the factor k4

– of volume by the factor k³

– of energy losses by the factor k³

With increasing motor power the efficiency and the ratio of

power to costs improves [1]

[1] Spring, E. Elektrische Maschinen: Eine Einführung Springer Berlin Heidelberg, 2009

[2] Pyrhonen, J. et al. Design of Rotating Electrical Machines Wiley, 2008 Efficiencies of totally enclosed 4-pole induction motors [2]

Conclusion:

Replacing two low powered electrical machines with one high powered electrical machine results in

improved efficiency and cost savings

9

Powertrain Efficiency (Example)

100 72% 82% 87% 88%

90 74% 83% 87% 89% 88% 88%

80 75% 84% 88% 90% 90% 88%

70 76% 85% 89% 90% 91% 88% 88%

60 77% 86% 89% 90% 91% 91% 88% 86%

50 77% 86% 90% 91% 91% 92% 91% 87%

40 77% 85% 90% 91% 91% 92% 91% 89% 87% 86% 86%

30 76% 84% 90% 90% 91% 91% 91% 90% 89% 88% 86% 86%

20 72% 81% 87% 89% 89% 89% 89% 88% 88% 87% 87% 85%

10 68% 73% 83% 85% 84% 84% 84% 82% 83% 83% 82% 82%1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

To

rqu

e [

Nm

]

Speed [rpm]

200 80% 88% 90% 92%

180 81% 88% 91% 92%

160 82% 89% 91% 93% 92%

140 83% 89% 92% 93% 93% 91%

120 83% 90% 92% 93% 94% 93% 90%

100 84% 90% 92% 93% 94% 93% 92% 90% 89%

80 84% 90% 92% 93% 94% 93% 93% 92% 90% 88%

60 84% 89% 92% 93% 93% 93% 93% 92% 91% 90% 86%

40 83% 89% 90% 91% 92% 93% 93% 92% 91% 91% 89% 89%

20 79% 85% 87% 88% 89% 89% 90% 90% 89% 88% 87% 87%1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Rotational Speed [rpm]

To

rqu

e [

Nm

]

PTU - Disconnect

RDU - Disconnect

PMSM + Inverter (Pmax=100 kW)

GearboxGearbox

PMSM + Inverter (Pmax=50 kW)100 72% 82% 87% 88%

90 74% 83% 87% 89% 88% 88%

80 75% 84% 88% 90% 90% 88%

70 76% 85% 89% 90% 91% 88% 88%

60 77% 86% 89% 90% 91% 91% 88% 86%

50 77% 86% 90% 91% 91% 92% 91% 87%

40 77% 85% 90% 91% 91% 92% 91% 89% 87% 86% 86%

30 76% 84% 90% 90% 91% 91% 91% 90% 89% 88% 86% 86%

20 72% 81% 87% 89% 89% 89% 89% 88% 88% 87% 87% 85%

10 68% 73% 83% 85% 84% 84% 84% 82% 83% 83% 82% 82%1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

To

rqu

e [

Nm

]

Speed [rpm]

Gearbox


Dual motor AWD

Low motor efficiency

Double load

independent losses of

gearbox and inverter

Single motor with ActiveConnect AWD

High motor efficiency

Load independent losses of single


Low drag loss of PTU and RDU in

disconnect

10

Powertrain Efficiency (Example)

100 72% 82% 87% 88%

90 74% 83% 87% 89% 88% 88%

80 75% 84% 88% 90% 90% 88%

70 76% 85% 89% 90% 91% 88% 88%

60 77% 86% 89% 90% 91% 91% 88% 86%

50 77% 86% 90% 91% 91% 92% 91% 87%

40 77% 85% 90% 91% 91% 92% 91% 89% 87% 86% 86%

30 76% 84% 90% 90% 91% 91% 91% 90% 89% 88% 86% 86%

20 72% 81% 87% 89% 89% 89% 89% 88% 88% 87% 87% 85%

10 68% 73% 83% 85% 84% 84% 84% 82% 83% 83% 82% 82%1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

To

rqu

e [

Nm

]

Speed [rpm]

200 80% 88% 90% 92%

180 81% 88% 91% 92%

160 82% 89% 91% 93% 92%

140 83% 89% 92% 93% 93% 91%

120 83% 90% 92% 93% 94% 93% 90%

100 84% 90% 92% 93% 94% 93% 92% 90% 89%

80 84% 90% 92% 93% 94% 93% 93% 92% 90% 88%

60 84% 89% 92% 93% 93% 93% 93% 92% 91% 90% 86%

40 83% 89% 90% 91% 92% 93% 93% 92% 91% 91% 89% 89%

20 79% 85% 87% 88% 89% 89% 90% 90% 89% 88% 87% 87%1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Rotational Speed [rpm]

To

rqu

e [

Nm

]

PTU - Disconnect

RDU - Disconnect


GearboxGearbox

PMSM + Inverter (Pmax=50 kW)100 72% 82% 87% 88%

90 74% 83% 87% 89% 88% 88%

80 75% 84% 88% 90% 90% 88%

70 76% 85% 89% 90% 91% 88% 88%

60 77% 86% 89% 90% 91% 91% 88% 86%

50 77% 86% 90% 91% 91% 92% 91% 87%

40 77% 85% 90% 91% 91% 92% 91% 89% 87% 86% 86%

30 76% 84% 90% 90% 91% 91% 91% 90% 89% 88% 86% 86%

20 72% 81% 87% 89% 89% 89% 89% 88% 88% 87% 87% 85%

10 68% 73% 83% 85% 84% 84% 84% 82% 83% 83% 82% 82%1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

To

rqu

e [

Nm

]

Speed [rpm]

Gearbox


Dual motor AWD

Low motor efficiency

Double load

independent losses of


Single motor with ActiveConnect AWD

High motor efficiency

Load independent losses of single


Low drag loss of PTU and RDU in

disconnect

11

Efficiency Simulation Results

Basis drive cycle: WLTP

Simulation with a range of different PMSM

Disconnection thresholds have been

established below 40 km/h

Potential energy savings by

ActiveConnect AWD:

~ 9 % vs. permanent dual motor system

~ 6 % vs. dual motor system with EDD

16

17

18

19

20

AWD -Permanent

AWD withEDD

FWD only 30 km/h 50 km/h 70 km/h 100 km/h 120 km/h AWD only

En

erg

y C

on

sum

pti

on [kW

h/1

00km

]

Single motor with mechanical ActiveConnect systemDual motor system

Disconnect threshold

Typical disconnection threshold

(v < 40 km/h)

(Battery: 60 kWh)-6

%

-9 %

1212

Cost Comparison

Inverter Motor

(PMSM)

Transmission ActiveConnect

AWD System

Cost benefit is achieved by single motor

concept due to

– reduced number of complex drive

components

– generating drive power by one central

motor

Cost estimate based on current market

prices

– Inverters, motors, transmissions and

ActiveConnect-AWD evaluated

– Cost of wiring, cooling and potential

battery modification not considered

4%

9%8%

13%

ActiveConnect withTwinster RDU

ActiveConnect withBooster RDU

Cost benefit by ActiveConnect AWD

vs. Dual Motor Systemwith permanent AWD

vs. Dual Motor Systemwith Front Axle EDD

1313

Mobility and Dynamics

Dual motor AWD

Dual motor system

– Axle torque is limited

to the torque of the

respective motor

Single motor with

mech. AWD

– Full torque available

on both axles

– Twinster enables

torque vectoring and

cross-axle locking

Single motor with mech. AWD (Twinster RDU) low-µ

low-µ

low-µ

low-µ

high-µ

high-µ

high-µ

high-µ

high-µ

high-µ

1414


Dual motor AWD

Dual motor system



respective motor

Single motor with

mech. AWD


on both axles



cross-axle locking


low-µ

low-µ

low-µ

high-µ

high-µ

high-µ

high-µ

high-µ

high-µ

1515


Dual motor AWD

Dual motor system



respective motor

Single motor with

mech. AWD


on both axles



cross-axle locking


low-µ

low-µ

low-µ

high-µ

high-µ

high-µ

high-µ

high-µ

high-µ

1616


Dual motor AWD

Dual motor system



respective motor

Single motor with

mech. AWD


on both axles



cross-axle locking

– Mobility benefits on

poor road surfaces

and off-road,

significantly

improved driving

dynamics


low-µ

low-µ

low-µ

high-µ

high-µ

high-µ

high-µ

high-µ

high-µ

1717

Application Scenarios for Electrified Vehicles

Ba

tte

ry

Ba

tte

ry

Ac

tiv

eC

on

ne

ct

AW

DV

ari

ab

el

ICE HEV

(P1 – P3)

DHT BEVeAxle with

integrated PTU

DHT with

integrated PTU

GKN’s ActiveConnect

system is the AWD

solution for all vehicle

concepts!

1818


Ideal solution in the low and medium-price segment

or in the commercial vehicle sector

Cost reduction is particularly relevant

Batteries tend to be smaller (simplified integration of

propshaft)

Effects of propshaft on passenger compartment are

less critical

Optimum use of the efficiency advantage

Mobility benefit is especially considerable

Pyrhonen, J. et al. Design of Rotating Electrical Machines Wiley, 2008

Multi-speed transmissions are a challenge for dual

motor systems

two multi-speed gearboxes are needed

or a compromise regarding efficiency and driving

performance has to be found

AWD can be provided by mech. System

with a single multi-speed transmission

Front:

Booster

Rear: eTwinster 2speed

with integrated PTU

1919


OEM with low market share in AWD

Hybridization of front axle to achieve high

reduction in fleet consumption (P1 – P3/DHT)

+ Simplified battery design

+ No impact on passenger

compartment

- Additional engineering

effort for rear axis

Electrified Rear Axle

+ Efficiency benefit

+ Cost reduction

+ Enhanced mobility and

driving dynamics

Mech. ActiveConnect AWD

AWD options

OEM with average market share in AWD

Option between P4 axle or P1 – P3/DHT with

mechanical ActiveConnect-AWD



compartment



P4 Axle

+ Hybridization covers full

vehicle fleet


driving dynamics

+ Electric AWD driving

+ Recuperation on both axles


AWD options

2020


OEM with low market share in AWD

Hybridization of front axle to achieve high

reduction in fleet consumption (P1 – P3/DHT)



compartment



Electrified Rear Axle

+ Efficiency benefit

+ Cost reduction


driving dynamics


AWD options

OEM with average market share in AWD

Option between P4 axle or P1 – P3/DHT with

mechanical ActiveConnect-AWD



compartment



P4 Axle

+ Hybridization covers full

vehicle fleet


driving dynamics

+ Electric AWD driving

+ Recuperation on both axles


AWD options

2121

Summary

Application scenarios for electrified vehicles

BEV:

– Recommended for low and medium price segment or

commercial vehicles

– Beneficial for BEVs with multi-speed transmission

HEV:

– Recommended for OEMs with low to medium AWD

market share

Enhanced DRIVING DYNAMICSdue to

Twinster Technology

COST REDUCTION by mechanical

solution up to 13 %

ENERGY SAVINGS over 9 % possible, supported by growth laws

and ActiveConnect

Full torque available on both axles for superior MOBILITY

AND OFFROAD CAPABILTITIES

GKN’s mechanical ActiveConnect system is the

attractive AWD solution for hybrid and battery

electric vehicles!

As an alternative approach to dual motor solutions,

AWD can be provided by GKN’s ActiveConnect system

2222

Global Leader in Traditional and Electrified Drivelines

gkn's activeconnect all-wheel drive system · 2019-12-18 · 2 awd systems in the age of...

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