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Workshop 2011Electric Powertrain
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Introduction
Name: Robert Weingart
Course of study: automotive engineering
focus: combustion engines
Team: WHZ Racing Team
Zwickau
Career in FS: season 2010: team engine
season 2011: team power train
season 2012: team leader power train
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Structure of Presentation
1. Targets of Development
2. Preliminaries
3. Electric Motor4. Wheel Hub Integration
5. Problems
6. Summary
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Structure of Presentation
1. Targets of Development
2. Preliminaries
3. Electric Motor4. Wheel Hub Integration
5. Performance
6. Problems
7. Summary
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Targets:
electric drive allows independent drive of each wheel
helps to improve vehicle dynamics
extra power through front wheels better performance in slippery conditions
increases recuperation from brake energy
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Important Facts of Development:
keep additional weight low
maximize the efficiency
integration in wheel hubs control the power by torque vectoring
minimize additional inertias (z-axis, steering)
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Structure of Presentation
1. Targets of Development
2. Preliminaries
3. Electric Motor4. Wheel Hub Integration
5. Performance
6. Problems
7. Summary
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Investigation
additional weights at the front axle with regard to:
moment of inertia
unsprung masses
weight transfer through acceleration
transferable forces (x-direction) limited by wheel load (F_z)
use of tire data diagram
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Investigation
calculation of additional weight per wheel:
increases the inertia (around z-axis) by J=5,85 kgm per wheel
part weight [kg]
motor (rotor + stator) 2,8
gearbox 1,0
drive shaft 0,6
rpm-sensor 0,1
hub/ upright 0,8
bearing 0,1
housing 0,6
= 6,0 kg
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Validation
test drive with additional masses (2x 6,0kg):
located in the wheel hubs/ in the center of gravity
track:
skid pad
slalom parcours (section like autoX)
results:
equal lap time at skid pad
slower time at slalom parcours
slower behavior of the car while steering
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Recuperation
reference lap from endurance 2010 of combustion car with
P=58kW
calculation of needed energy/ possible regenerating from
brake energy
detailed look at negative power
note dynamic weight transfer to front axle
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Power Chart ofFSG10 AX
power[kW
]
-80
-60
-40
-20
0
20
40
60
80
time [s]
0 5 10 15 20 25 30 35 40 45 50 55
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Possible Recuperation
s
kW
limited performance for energy recovery on the front axle
limited performance for energy recovery on the rear axle
limited performance for energy recovery of the vehicle
power[kW]
-60
-50
-40
-30
-20
-10
0
time [s]
0 5 10 15 20 25 30 35 40 45 50 55
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Structure of Presentation
1. Targets of Development
2. Preliminaries
3. Electric Motor
4. Wheel Hub Integration
5. Performance
6. Problems
7. Summary
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Motor
high speed motor from industrial sector
normally used for machining tools
lightweight motor with high rpm
designed as a support drive
integrated temperatur sensor
external rpm-sensor
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Structure of Presentation
1. Targets of Development
2. Preliminaries
3. Electric Motor
4. Wheel Hub Integration
5. Performance
6. Problems
7. Summary
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Different Concepts of Final Drive
criterias
weighting factor
Varianten
planetary gear spur gear
fi fj f=fi*fj p p*f p p*f
a. energy
0,7
/ / / / / /
efficiency 0,4 0,28 3 0,84 2 0,56
weight 0,3 0,21 2 0,42 1 0,21
wheel bearings 0,3 0,21 3 0,63 3 0,63b. inertias
0,1
/ / / / / /
steering axis 0,4 0,04 2 0,08 1 0,04
z-axis 0,4 0,04 2 0,08 3 0,12
rotating masses 0,2 0,02 3 0,06 1 0,02
c. manufacturing
0,2
/ / / / / /
assembling effort 0,3 0,06 2 0,12 1 0,06
tolerances 0,2 0,04 2 0,08 1 0,04
number of parts 0,2 0,04 2 0,08 1 0,04
complexity 0,3 0,06 2 0,12 1 0,06
total 1 / 1 / 2,51 / 1,78
changeable cells x x x x
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Comparison of Both Concepts
spur gear planetary gear
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Scheme of Front Motor Unit
stator
rotor
electric motorplanetary
gear
sensor
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Further Tests
investigation of connectors for
cooling system
buckling test by simulating a
reference lap from FSG
different hoses with different
buckling protections were tested
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Buckling Test
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Before Assembly
overview of all parts flanges and shafts
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Structure of Presentation
1. Targets of Development
2. Preliminaries
3. Electric Motor
4. Wheel Hub Integration
5. Performance
6. Problems
7. Summary
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Load Spectrum
values of torque from control unit show distribution during
FSG11 autoX
long time at full load,
zero load during cornering
improved performance in
rainy conditions
(FSUK11 and FSG11 EN)
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Structure of Presentation
1. Targets of Development
2. Preliminaries
3. Electric Motor
4. Wheel Hub Integration
5. Performance
6. Problems
7. Summary
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Perfomance while ACC
low efficiencies (gearbox, sealings, bearings, )
errors from control unit/ converter motor switched off
0,00
0,25
0,50
0,75
1,00
0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5
P[kW]
t [s]
efficiency at FSG11 ACC
P_mech_fl/P_el_fl
P_mech_fr/P_el_fr
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t1:40 3:20 5:00 6:40 8:20 10:00 11:40 13:20 15:00 16:40 18:20 20:00 21:40 23:20 25:00 26:40 28:20
km/h
0
7.5
15
22.5
30
37.5
45
52.5
60
67.5
75
82.5
90
C
0
25
50
75
100
125
150
175
Temperatures
T=150C
T=120C
velocitytemperature water temp.
current
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Structure of Presentation
1. Targets of Development
2. Preliminaries
3. Electric Motor
4. Wheel Hub Integration
5. Performance
6. Problems
7. Summary
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Summary
support drive at front axle in small installation space
possible improvement of performance by torque vectoring
high recuperation ability
additional weight of 30kg (motors, lines, batteries, )
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See you at Hockenheim
01. 05. August 2012