ika-Meetup: E-Mobility Herzlich Willkommen · Global Market Relevance of PHEV and BEV 0 10 20 30 40 50 2018 2025 2030] 2.0 12.5 24.5 22.6 43.4 CAGR: +23% CAGR: +29% New Policies-Szenario

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High-voltage battery systems

Challenges and opportunities for automotive suppliers

Alexander Busse

fka GmbH

19.03.2020


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Vortrag

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Alexander Busse

fka GmbH

19.03.2020

© fka GmbH20nm0000.pptx

03/19/2020

Slide No. 6

High-Voltage Battery Systems in Vehicles

Challenges and Opportunities for Automotive Suppliers

Alexander Busse, Aachen, March 19th


03/19/2020

Slide No. 7

fka GmbH

Overview

Basic Data

Founded in 1981 as a spin-off from the Institute for Automotive Engineering (ika) of RWTH Aachen

University

Together with co-operation partner ika access to a total staff of approx. 470 employees

Project structure

55% Advanced engineering

20% Serial vehicle development

25% Future development and others

References

Automotive customers from Europe, USA and Asia

OEM and suppliers

Public funded research


03/19/2020

Slide No. 8

fka GmbH

Developing tomorrows mobility

STRATEGY & CONSULTING

VEHICLE CONCEPTS

CHASSIS & ACOUSTICS

BODY

DRIVETRAIN & THERMAL MANAGEMENT

ELECTRICS / ELECTRONICS

AUTOMATED DRIVING

USER EXPERIENCE

Our holistic approach and unique infrastructure for

simulation, testing and evaluation allows us to see the

big picture and be your specialist for details at the same

time.


03/19/2020

Slide No. 9

Introduction and Motivation

Global Market Relevance of PHEV and BEV

0

10

20

30

40

50

203020252018Ann

ua

l P

HE

V+

BE

V n

ew

regis

tration

s

[mill

ion u

nits]

2.0

12.5

24.522.6

43.4

CAGR: +23%

CAGR: +29%

New Policies-Szenario

EV30-Szenario

»Massive increase in the importance of PHEV and BEV by 2030, regardless of the assumed scenario

■ Annual average growth rate 23-29 %

■ At EUR 120/kWh and Ø 40 kWh (incl. PHEV) per vehicle in 2025: market of EUR 60-120 billion

Source: [IEA19]1 2 3 4 5


03/19/2020

Slide No. 10


Schematic Structure of a HV Battery System

Battery Cell

Battery tray

Top cover

Cooling system/

Thermal

management

Lattice

reinforcement

Battery frame

Floor/

Underbody

protection

Battery Electric Vehicle

Battery housing & peripherals

Battery

Module

Lithium-IonLithium Sulphur

Modular

battery system

Stand-alone

Module

Pouch

Cylindrical

Prismatic

Solid State…

Battery

System

FOCUS

Cell Chemistry

Cell types

Module configuration

Sources: [DEU12], Image source: Audi1 2 3 4 5


03/19/2020

Slide No. 11

FOCUS


Positioning of Companies in the Value Chain (Examples)

» Supplier activities especially in battery case production

»Numerous metal forming companies, but also pure material producers who want to increase their added value

»Question about the future material mix is of crucial importance for suppliers and OEMs

Case &

System

Manu-

facturing

Cell

Production

Module

Production

Vehicle-

Integration

Use

End of Life

Second Life

Recycling

Sources: [BER18]1 2 3 4 5


03/19/2020

Slide No. 12

Agenda


Requirements and Development Trends of HV Battery Systems

Lightweight Design

Thermal Management

Conclusion and Strategic Implications

1

2

3

4

5

Guiding Questions

Which materials are most suitable for certain components of the battery system?

What are the strategic implications for suppliers?

2

1 2 3 4 5

Steel Aluminum

CFRP


03/19/2020

Slide No. 13


Requirements of different Stakeholders

Durability of housing,

electronics and

modules

Good

driving

performance

High

Range

Less

environmental

footprint

Less

resource input

Manufacturability

tightness &

corrosion

protection

Structural

safety

Fire protection

and thermal safety

Electrical

safety

Price / Costs

SafetyMobility

Experience

Efficiency

Low

charging

time

High

charging comfort

Structural

vehicle-

integration

End

Customer

Society

Industry

Highest safety level, without

limit the mobility experience

1 2 3 4 5

Legislation


03/19/2020

Slide No. 14

So far: Conversion Design (e.g. e-Golf)

Battery system

Electric MotorPower Electronics ChargerElectric Motor

Battery system

ChargerPower Electronics

x

y

x

y


From Conversion to Purpose Design and Implications

Today: Purpose Design (e.g. VW MEB)

» Separated topology of the system by retrofitting into

existing package

» Utilization of vehicle tunnel and rear, otherwise

inhomogeneous design by fitting into the vehicle

» Simple geometry (rectangle) between axes

» Length-scalable in modular system with wheelbase

» Comparable approaches between different cell types,

materials, OEMs and suppliers?

Image source: VW1 2 3 4 5


03/19/2020

Slide No. 15

Tesla Model S / XChevrolet Bolt / Opel Ampera-e


Comparable Designs despite different Framework Conditions

60 kWh

Reinforcement structure Reinforcement structure

75-100kWh

» Materials used:

■ floor, tray: steel

■ Top cover: SMC (fiber composite

plastic)

» Architecture:

■ Reinforcement: longitudinal and

lateral beams

■ Tray: deep-drawn

■ No frame

■ Floor: Single tray

» Materials used:

■ Floor / Frame: aluminum

■ Top Cover: steel

» Architecture:

■ Reinforcements: Lateral beams,

one longitudinal beam

■ No tray

■ Frame: Extruded

aluminum profiles

■ Floor: Single sheet with titanium reinforcement

Image sources: Opel, Tesla1 2 3 4 5


03/19/2020

Slide No. 16

Agenda



Lightweight Design

Thermal Management


1

2

3

4

5

3

Steel Aluminum

CFRP

1 2 3 4 5


03/19/2020

Slide No. 17


electronics and

modules

Good

driving

performance

High

Range

Less

environmental

footprint

Less

resource input

Manufacturability

tightness &

corrosion

protection

Structural

safety

Fire protection

and thermal safety

Electrical

safety

Price / Costs

SafetyMobility

Experience

Efficiency

Low

charging

time

High

charging comfort

Structural

vehicle-

integration

End

Customer

Society

Legislation

Industry

Highest safety level, without

limit the mobility experience

Safe

and more

efficient

Lightweight

Design

Lightweight Design

Requirements addressed by Lightweight Construction

1 2 3 4 5


03/19/2020

Slide No. 18

"Thermal Runaway"

Area "Safe Lightweight Design“

Motivation for high Safety Requirements

Boeing 787 "Dreamliner" Tesla Model S

"Thermal Propagation"

Trigger HeatInternal cell

Reactions

1 2 3 4 5


03/19/2020

Slide No. 19


Motivation for high Safety Requirements

Sources: [AFS17] [FIN19] [HAM19]

[HEU12]1 2 3 4 5


03/19/2020

Slide No. 20


Mechanical Protection - Example Pile Crush

Fx = Fy = 100 kN

rPole = 75 mm

F

F

Top view

y

xz

Side view

Frame construction

Tub construction

Longitu

dinal

beams

Cross

beams

Frame

x

y z

FMulti-chamber-

profile

Profile deformation

critical!

Module

Crush according to GB/T 31467.3

Sources: [MAS19]

z

y xz

y x

1 2 3 4 5


03/19/2020

Slide No. 21

Lightweight Design - Analytical Consideration of the Profile

Stiffness: Assumptions

» Exclusively elastic range

» Cross beams of the battery case form only supports

» Weight balance support bearing

» External dimensions (design space) identical

» No consideration of the joining technology

MaterialsAluminum

CFRP

(isotropic)

𝑙

2

𝑙

𝐹

𝐹

2

𝐹

2

3𝐻

𝐻

𝑡2

2 ∙ 𝑡1

𝑡1

𝐵

Material CP-K

900Y1180TEN AW-7108

HM/EP, 𝜑 = 60%[25 50 25]

Manufacturing Roll forming Extrusion Wrap/glue

Young's modulus [N/mm²] 210.000 70.000 94.000

Yield strength 𝑹𝒑 𝟎,𝟐 [N/mm²] 900 320 linear-elastic

Tensile strength 𝑹𝒎 [N/mm²] 1.180 360 780

tmin [mm] | ratio t1/t2 1,6 | 1 2 | x > 1 1 | x > 1

Density 𝜌 [kg/m³] 7.800 2.700 1.600

Steel

x

z

y

A A

A-A

Sources: [CHA15] [DUB05] [MAS19]

[NED20] [THY20] [UNC15]1 2 3 4 5


03/19/2020

Slide No. 22

Lightweight Design

Analytical Consideration of the Profile Stiffness: Results

» Deflection

» Area moment of

inertia:

Rectangle

» Area moment of

inertia

Profile

3𝐻

𝐻

𝑡2

2 ∙ 𝑡1

𝑡1

𝐵

𝐹

x

z

y

𝑓𝑦 =𝐹 ∙ 𝑙

48 ∙ 𝐸 ∙ 𝐼𝑧

AluminumCFRP

(isotropic)Steel

𝐼𝑍 =𝐻 ∙ 𝐵³

12

𝐼𝑍 = 3 ∙𝐻 ∙ 𝐵3 − (𝐻 − 2 ∙ 𝑡2) ∙ (𝐵 − 2 ∙ 𝑡1)

3

12

» Lightweight advantage of aluminum much less than expected

» Concrete result depending on geometry (b, h, d)

» Degree of freedom / material limitations to be observed

■ e.g. high design freedom for aluminum extrusions

■ e.g. non-isotropic, fiber-suitable CFRP construction

𝑙

2

𝑙

𝐹

𝐹

2

𝐹

2

Sources: [DUB05]

t2 [mm] 1,6 9,6 6,3

fy [mm] 3,2

mProfile [kg] 3,25 2,99 1,64

∆mProfile [%] - 8 % 65 %

1 2 3 4 5

F [kN] 100

l [mm] 500

B [mm] 60

H [mm] 30

t1 [mm] 1,6 2 1


03/19/2020

Slide No. 23

Lightweight Design

Simulative Consideration of the Profile: Results

t=2.5mm

Weight: 1.77 kg

∆mProfile: 14%

t=1mm

Weight: 2.05 kg

AluminumSteel

Material: 6082T6

Material: CP1000


03/19/2020

Slide No. 24

Lightweight Design

Background Life Cycle Assessment (LCA) - Cradle to Grave

(CO2)

Life

Cycle

Assessment

Emissions "Cradle to Gate"

Raw material mining

Component production

Vehicle assembly

Production

Utilization

"Cradle to grave"

Production

+ Utilization

- Recycling

=Total balance

sheet

GWP [kg CO2e]

Emissions "Well-to-Wheel"

Well-to-Tank: Fuel & power supply

Tank-to-Wheel: Vehicle emissions

Emissions "End-of-life" / "grave"

Disassembly

Reutilization

Credit notes possible

Recovery

Sources: [VOL20]1 2 3 4 5


03/19/2020

Slide No. 25

Lightweight Design

Comparative CO2-LCA for the battery box frame

0

200

400

600

800

GW

P [

kg

CO

2e]

207

103

35 275

AluminumCFRP

(isotropic)Steel

Electricity

mix

(=const.)

0

200

400

600

800

GW

P [

kg

CO

2e]

3410103 79

449190

544

285

218 9 110117

644

10410

529

5 10

339 354

» In the production of (primary) materials, steel has a massive advantage over Al and CFRP in the German electricity mix

» Steel loses the GWP advantage if the production of aluminum is almost exclusively based on renewable energy

» With a GWP of cell production of ca. 75 kg CO2e/kWh, the share of the case is low but significant (> 10 %)

Balance sheet for frames

(14 x partial profile)

Potential:

Reduction down to < 10

Potential:

Reduction down to < 120

Positive emissions

Potential:

CFRP Recycling

m = 45.5 kg m = 41.9 kg m = 23.0 kg

Sources: [NN19] [IVL19]1 2 3 4 5


03/19/2020

Slide No. 26



Lightweight Design

Thermal Management


1

2

3

4

5

4


03/19/2020

Slide No. 27


Requirements of different Stakeholders


electronics and

modules

Good

driving

performance

High

Range

Less

environmental

footprint

Less

resource input

Manufacturability

tightness &

corrosion

protection

Structural

safety

Fire protection

and thermal safety

Electrical

safety

Price / Costs

SafetyMobility

Experience

Efficiency

Low

charging

time

High

charging comfort

Structural

vehicle-

integration

End

customer

Society

Legislation

Industry

Performant

Thermal-

management

1 2 3 4 5


03/19/2020

Slide No. 28

Thermal Management

Impact of Thermal Management on Customer Satisfaction

^Image source: YouTube1 2 3 4 5


03/19/2020

Slide No. 29

Thermal Management

Design Criteria for the Thermal Management System

Customer Requirements

» Fast charging (low charging

time), high continuous driving

load

■ High durability

■ High availability of power

» Everyday use

■ Recuperation

■ Availability at frost

»General conditions

Limitations

» Irreversible cell degradation at too high

temperature lower battery capacity

■ ∆Tavg = +10 K

Service life reduced by up to 50 %

■ Homogeneous aging

Same internal resistance

» Very high internal resistance at T < 0°C

» Battery performance increases with

temperature

■ Above 50°C, however, hazard of thermal

runaway

» Lowest possible pump capacity to reduce

costs

Design Targets

» 20°C < Toptimal < 40°C

» ∆Tin cell < 5…10 K

» ∆ Tintercell < 5 K

» Tmin > 0°C if possible

» Toptimal > 20°C

» Tmax < ~50°C

» Pressure drop ∆p min

(= poutlet - pinlet)

Sources: [KOR13] [ISI13] [KOR18]

[MEU11]1 2 3 4 5


03/19/2020

Slide No. 30

Heat of Reaction

Thermal Management

Heat balance of the battery cell

ሶ𝑄𝐽𝑜𝑢𝑙𝑒 = 𝑖² ∙ 𝑅𝑖𝑛𝑡

ሶ𝑄𝑅𝑒𝑎𝑘 = 𝑖 ∙ 𝑇𝑖𝑛𝑡 ∙𝜕𝑈𝑜𝑐𝜕𝑇𝑖𝑛𝑡

Structure of Battery Cell Heat Generation Contact Points Heat Sink

Floor coolingFloor and

top cover cooling

Intercell cooling

with cooling plates

Intercell cooling

with meandering

Immersion-

cooling Pole cooling

i - amperage

Tint - Cell temperature

Uoc - open circuit voltage

with:

Joule Losses

i - amperage

Rint - Internal resistance

with:

> 0

or

< 0

Dominant Effect

Dominant Design

(exception: Tesla)

Sources: [BAE19] [HOP16] [WIE09]

[MEU11]

(charging) power:𝑃𝑐ℎ = 𝑖 ∙ 𝑈𝑐ℎwith: Uch - Charge voltage

1 2 3 4 5


03/19/2020

Slide No. 31

Temperature-

conductivity

Battery system

Thermal Management

Relevant Design Parameters to met the Regulations

Pressure drop ↓ Heat transfer ↑

Dynamics ↑

in transient operation

Channel size

Flow velocity

Channel geometry

Volume flow

Quality of heat transfer

Wall thickness

Surface area [m²]

Pump capacityType and efficiency of the heat

sink

Sources: [BAE19] [HOP16] [WIE09]

[MEU11] [MAS19]1 2 3 4 5


03/19/2020

Slide No. 32

Thermal Management

Comparison of heat transfer / wall thickness by Biot number

»Ratio of convective heat-

transition at the surface and

heat conduction in the solid state

■ α: Heat transfer coefficient at the surface the

flowing fluid

■ L: characteristic length of heat conduction in

the solid (e.g. wall thickness of the cold

plate)

■ λ: Thermal conductivity of the solid»With a cooling plate that is approximately 3 times thinner than

steel, a temperature field similar to that of aluminum can be

generated

»Mechanical strength is comparable

𝐵𝑖 =ൗ𝐿 𝜆

Τ1 𝛼=

𝛼∙𝐿

𝜆=

Thermal ResistivityHeat Transmission Resistance

; [−]

» Equal Biot Number and similar geometry with other

scales similar temperature fields

» Equal Biot Numbers for steel & aluminum

achievable?

𝐿

𝛼

Bio

tN

um

ber

Wall thickness of cooling plate [mm]

Definition Biot number

𝜆

0,00

0,02

0,04

0,06

0,08

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5

Aluminum

Comparison St/Al with α = 2500 W

m2∙K

Steel

Sources: [BAE19] [THY20] [NED20]1 2 3 4 5


03/19/2020

Slide No. 33

Definition Thermal Diffusivity

Thermal Management

Comparison of Thermal Diffusivity

»Describes the temporal change of the spatial

distribution of temperature in the solid state due to

heat conduction as a result of a temperature

gradient

■ 𝜆: Thermal conductivity of the solid

■ 𝜌: Density

■ c: Heat capacity

a =𝜆

𝜌 ⋅ 𝑐=

Heat Conduction

Thermal Mass; [

mm2

s]

» Analogous to kinematic viscosity: Measure of the

"flow property" of the temperature through a solid

body in the unsteady state

■ The higher the thermal conductivity, the faster

the temperature propagation in the body

𝜌 [kg/m³] 7800 2700

𝜆 [W/m*K] 15 60 120 200

c [J/kg*K] 470 900

a [mm²/s] 4.1 16.4 49.4 82.3

Aluminum

Steel

Result Thermal Diffusivity

» Transient homogenization behavior of steel approx. min.

factor 3 (up to 20) worse than aluminum

Sources: [BAE19] [THY20]

[NED20]

Overall Conclusion Thermal Management

» Inherent disadvantages

» (Partial) compensation

makes economic sense?

Aluminum» State-of-the-art

» Another advantage:

production process

Steel

1 2 3 4 5


03/19/2020

Slide No. 34



Lightweight Design

Thermal Management


1

2

3

4

55


03/19/2020

Slide No. 35


Conclusion

» The battery system has a significant impact on overall vehicle requirements

» Lightweight design - Stiffness requirements

» The blanket assumption of lightweight construction potentials is useless,

the result is determined by the overall system, no clear preference

» Material and production-optimized design

» Steel offers limited geometrical freedom (bending / roll forming)

» Aluminum extrusions allow a high degree of design freedom

» Fiber-compatible design complex to make sensible use of CFRP

» Lightweight Design - LCA

» The impact of the battery case on CO2 lifecycle emissions is not negligible

and its relative importance continues to increase

» Thermal management

» Steel is basically suitable as a material for cooling plates in battery

systems, besides aluminum, but has inherent disadvantages

1 2 3 4 5


03/19/2020

Slide No. 36


Strategic Implications

» Inductive Charging

» Integration of the receiver plate into the

battery housing?

» Second Life / Recycling

» Design for recycling?

» Second life

» Reutilization of the battery system

in stationary applications?

» Which components?

» General

■ As cell costs fall, the relative importance of the other

battery system for overall costs will continue to

increase

» Metal Forming Cluster

■ e.g.

■ Flexibility with regard to the choice of material,

requires broad know-how in the area of production

» Cluster "Metal Material Producers"

■ e.g.

■ Examine strategic opportunities for the forward

integration of value creation

■ Use of specific material advantages in own concepts

and optimization of the CO2 footprint

» Cluster "Alternative Materials Specialists

■ e.g.

■ Focus on niches with high margin potential

4490

~570

40 kWh

~ 1460 ~480

1 2 3 4 5


03/19/2020

Slide No. 37

Battery System Development at fka GmbH

Process with three interacting layers

2.

Mechanical

Vibration

Acceleration

Deformation

Environment

Humidity, chemicals

Temperature, fire

Recycling

Electrics / Electronics

Charging, discharging

Short-circuit (internal/external)

EMC

Concept

System

Integration and

Validation

Full Vehicle

Testing

System

Specifications

Real Traffic

SOP

Requirements

& Use-cases

Component

Development

Idea

5.

4. Testing on system level

1. Scenario-based definition of requirements

(production, use-phase, repair & recycling)

Testing on vehicle level

Advanced testing

methods and infrastructureMulti-domain

battery system development

Multi-scale

simulation

Multi-parameter

optimisation

Deduction of specification on

system and component level

HiL testing

3. Holistic modeling,

simulation & optimisation

Battery-Management-System

Electrical Layout & connection

Thermal- Battery Layout

Mechanical Cell Integration

Benchmarking

[HIL17]


03/19/2020

Slide No. 38

Battery System Development

Agile combination of Simulation and Tests

Database

Battery systems, EVs & regulations

Agile design & Concept

development

Development approach

Modelling the mechanical cell propertiesBlack box

approach

Test facilities

Component

testing

Acustic / climate

chamber Drop tower

Pedestrian

protection

Servo-hydraulic

bench

Crash facility

Outdoor

Crash facility


03/19/2020

Slide No. 39

Battery System Development – Mechanical layer

Multi-Scale Modelling & Optimization of Batteries

Optimised battery integration by innovative protection systems and simulation tools

Battery concept & placement

• Reinforcement of battery

depending on position

Source: Gidas Database

Design Battery System Relevant load cases Cell tests FE Model (cell) Design validation

New concepts

Source: Ficosa

• Inflatable battery

protection structure

• Removable modules

Cell: Kokam 40 Ah pouch cell

Plastic strain battery cellsDeformed battery pack

Simulation

• Generation of cell

simulation model for full

vehicle simulation

Testing

• Identification of real life

loads


03/19/2020

Slide No. 40

» Assessment of thermal requirements

» Conception of suited thermal management designs & virtual integration

» Parameter studies on geometrical design, influences of material choices, etc.

» Simulative studies on hydro-thermal behaviour under various boundary conditions,

e.g. fast-charging or high transient cycles

» Battery testing and simulation chamber

» Electrical and thermal characterization of battery systems

under various boundary conditions

» Development of BMS and thermal management systems

» Dimensions: 2m x 2.5m x 2.2m (w/d/h)

» Temperature range: -40 – 70°C

» 2 K/min transient response

» Voltage range: 10-1000 V, current range: ± 1000A

» Max power: +/- 400 kW

Simulative thermal management system design and assessment Testbench for prototype validation

Top, bottom and module integrated cooling concepts, ©voestalpine

Battery System Development – Thermal layer

Thermal System Design


03/19/2020

Slide No. 41

fka GmbH

Steinbachstr. 7

52074 Aachen

Germany

Alexander Busse

phone +49 241 8861 167

e-mail [email protected]

web www.fka.de


Bitte merken Sie die nächsten Termine vor:

Vielen Dank !

Elektrische Antriebsstränge auf dem Prüfstand

Spezielle Anforderungen an (HD)-Antriebsstrang-Prüfstände

Dipl.-Ing. Marc von Papen (AVL DEUTSCHLAND GmbH)

14.05.2020

Reinventing the wheel

Why the Silicon Valley is reinventing the automobile and if this can actually work

Christian Roth (fka Silicon Valley)

23.04.2020

Certainly Unknown

Application of Neural Network Uncertainties in Automated Driving

Daniel Bauer (Ford Research & Advanced Engineering Europe)

18.06.2020


ika-Meetup powered by

Vielen Dank für die Unterstützung!

www.fka.de


Damian Backes

Institut für Kraftfahrzeuge – RWTH Aachen University

Steinbachstraße 7

52074 Aachen

Tel.: +49 241 80 25420

Fax: +49 241 80 22147

[email protected]

www.ika.rwth-aachen.de/meetup

Kontakt

Documents

ika-Meetup: E-Mobility Herzlich Willkommen · Global Market Relevance of PHEV and BEV 0 10 20 30 40 50 2018 2025 2030] 2.0 12.5 24.5 22.6 43.4 CAGR: +23% CAGR: +29% New Policies-Szenario