Optimizing Battery Cell, Module, Pack and Controls Design with Comprehensive Simulation

1 © 2014 ANSYS, Inc. August 21, 2014 ANSYS Confidential
Optimizing Cell, Module, Pack and
Controls Design with Comprehensive
Simulation
Sandeep Sovani, Ph.D.
Director, Global Automotive Industry
ANSYS Inc, Detroit
Acknowledgements: Xiao Hu and Scott Stanton, ANSYS Inc.

Virtual Product Development
Concept & Design
Physical
Prototype
Production
Simulation-Driven
Product Development
Today’s norm for automotive product development

Largest
Independent CAE simulation software company
Focused
Simulation is all we do.
Leading product technologies in all physics areas
Largest development team focused on simulation
Capable
2,700 employees
60 locations, 40 countries
Trusted
96 of top 100 FORTUNE 500 industrials
ISO 9001 and NQA-1 certified
Proven
Recognized as one of the world’s most innovative
and fastest-growing companies*
Independent
Long-term financial stability *BusinessWeek, FORTUNE
About ANSYS A Simulation Software Company

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About ANSYS
Advanced Physics Solvers

A multi-fidelity simulation toolset is essential
for complex systems such as batteries
Model Simulation Result
Requirement
Req 23: On request, the valve should close in 500us
X
Functional
simulation
System
simulation (0D)
High fidelity
simulation
(3D) - Open loop
validation
System
Validation
(0D-ROM-Ctrl)-
Close loop
validation
500us0
Pos
true
false
t
0
500us
t
Pos
Pmax
Actuator
t
Pos
0 500us
t
Pos
Pmax
500us
Pmax
Pmax

A Total Li-Ion Battery Simulation Solution
Module/Pack
Thermal Mgt
Durability
NVH
EMI/EMC
Electrode
Layout
Process
Life
SEI
Molecular
Materials
Powertrain
System
Integration
SmallScale
LargeScale
Cell
Charging
Discharging
Heating
Safety
ECM
CFD
ROM
FEA
ECM
CFD
FEA
Electro-
chemistry
ECM
ROM

A Total Li-Ion Battery Simulation Solution
Electric Circuit,
System Model
High Fidelity Physics,
Chemistry Models
Reduced Order Modeling (ROM)

Electrode Level - Electrochemistry
• Electrochemical Kinetics
• Solid-State Li Transport
• Electrolytic Li Transport
• Charge Conservation/Transport
• (Thermal) Energy Conservation
Li+
e
Li+
Li+ Li+
LixC6
Lix-Metal-oxide
e
Jump
  Li
ee
ee
j
F
t
cD
t
c 



 1)(
Impact of Discharge Rate on Capacity Charge Discharge CyclesTemperature Impact on Capacity
1/10 C
1/2 C
1 C
2 C
4 C
6 C
8 C
10 C
X. Hu, S. Lin, S. Stanton, SAE paper 2012-01-0665

U.S. Department of Energy CAEBAT Project
DOE’s Computer-Aided Engineering for Electric
Drive Vehicle Batteries (CAEBAT) program
ESim
Goals for the CAEBAT include:
• Developing standard battery engineering tools
to design cells and battery packs
• Improving overall battery performance, safety,
and predict battery life
CAEBAT Program:
• DOE Funded program; $7.0 M Investment
• Completion in August 2014

Newman P2D Electrochemistry Model in
ANSYS-Fluent (CAEBAT project)
Domains
• negative electrode
• separator
• positive electrode
• spherical particles
L. Cai and R.E. White, “Reduction of Model Order Based on Proper Orthogonal Decomposition for
Lithium-Ion Battery Simulations” J. of Electrochemical. Soc. 156(3) A154-A161 (2009).

Temperature Results Based on
Electrochemistry
-110
-90
-70
-50
-30
-10
10
30
50
0 200 400 600 800 1000 1200 1400
Current(A)
Time (s)

Cell Level – CFD Thermal
Temperature Distribution

Cell Level –Electro-Thermal
Current DensityCathode Anode
Current Density
  J 
)( UYJ ac  

Cell Level – ECM
Battery Equivalent Circuit Model (ECM)
Simulation Testing
X. Hu, L. Collins, S. Stanton, S. Jiang, "A Model Parameter Identification Method for Battery Applications", SAE 2013-01-1529.

• 28 cells are connected in a
module
• 4 modules are connected
to the final configuration
Module/Pack Level – ECM
Battery Pack ECM
Simulation Results

Cell Level – ECM Extraction Tool
ECM Extraction Toolkit
ECM Model
Workflow

Module Level – CFD Thermal
Temperature Distribution
Velocity Distribution
Initial
Optimized

Motivation of Reduced Order
Model(ROM)
 CFD as a general thermal analysis tool is
accurate.
 Can be computationally expensive for system level
analysis
 ROM can significantly reduce the model
size and simulation time.
 ROM is an import tool for system level
simulation.

Battery Thermal Behavior
via ROM
Type 1: Thermal Network
• Careful calculation and
calibration needed
• Accuracy compromises
Type 2: LTI – state space
• Can be as accurate as CFD
• No calibration
LTIt t
Step
Input
Step
Response
1

LTI ROM gives the same results as CFD. LTI
ROM runs in less than 2 seconds while
the CFD runs 2 hours on one single CPU.
X. Hu, S. Lin, S. Stanton, W. Lian, “A Foster Network Thermal Model for HEV/EV Battery Modeling,” IEEE TRANSACTIONS ON
INDUSTRY APPLICATIONS, VOL. 47, NO. 4, JULY/AUGUST 2011
X. Hu, S. Lin, S. Stanton, W. Lian, “A State Space Thermal Model for HEV/EV Battery Modeling", SAE 2011-01-1364
Heat Profile
LTI ROM for General Motors
Battery Module

Module Level – ROM for Thermal
ROM vs CFD
ROM for the Battery Module

 SVD = Singular Value Decomposition
 SVD ROM technology allows for quick temperature distribution
calculation in addition to average temperature calculation.
 Using a heat source from GM, SVD ROM is applied to the GM 16 cell case.
SVD ROM :
General Motors 16 Cell Test Case
Heat source used
S. Asgari, X. Hu, M. Tsuk, S. Kaushik, “Application of POD plus LTI ROM to Battery Thermal Modeling: SISO Case,” SAE 2014.-01-1843
X. Hu, S. Asgari, I. Yavuz, S. Stanton, C-C Hsu, Z. Shi, B. Wang, H-K Chu, “A Transient Reduced Order Model for Battery Thermal Management Based
on Singular Value Decomposition,“ Submitted to ECCE 2014.

SVD ROM Validation: GM 16 Cell Test Case
CFD (200 sec)
SVD ROM
(200 sec)
CFD (400 sec) CFD (600 sec) CFD (800 sec)
SVD ROM
(400 sec)
SVD ROM
(600 sec)
SVD ROM
(800 sec)
X. Hu, S. Asgari, I. Yavuz, S. Stanton, C-C Hsu, Z. Shi, B. Wang, H-K Chu, “A Transient Reduced Order Model for Battery Thermal Management Based
on Singular Value Decomposition,“ Submitted to ECCE 2014.

Temperature Distribution - Animation
Temperature calculated from CFD.
7 hr simulation time with 6 CPUs.
Temperature calculated from SVD ROM.
0.5 hr simulation time with 1 CPU.

 ECM calculates heat source and sends it to the two
ROMs.
 LTI ROM calculates average temperature and sends it to ECM.
 SVD ROM calculates temperature distribution.
GM Battery Module –
ECM Coupled with ROMs

ROMs/ECM Coupled Results
LTI ROM calculates average temperature.
SVD ROM calculates temperature field.
– Needs to be post-processed back in FLUENT.
ECM calculates electrical performance.
Average Cell Temperature Battery Voltage as a Function of Time

Module/Pack Level –
Bus Bar Model
Electromagnetic FEA Analysis for Busbar
RLC Network Extraction

Full Battery Simulation
Voc = -1.031*exp(-35*(abs(IBatt.V/Vinit))) + 3.685 + 0.2156*(abs(IBatt.V/Vinit))
- 0.1178*(abs(IBatt.V/Vinit))^2 + 0.3201*(abs(IBatt.V/Vinit))^3 +
0.3/30.0*(U1.Temp_block_1-273)

System Assembly
Battery ROM Inverter ROM Machine ROM
Embedded Software
Behavioral Models

HIL
PIL
SIL
MIL
Plant ModelEmbedded Controller
Control Software Development
C code
DesignImplementation

Control Software Development
Bringing Aerospace Safety Best Practices to Automotive
SCADE = Safety Critical Application Development Environment
Certified Automatic Embedded Code Generation
Certified Embedded Code Generation:
ISO 26262 certification up to ASIL D

Summary
 Effective virtual product development of batteries
needs combination of
High fidelity physics and chemistry models
Circuit/system level models
Reduced Order Methods (ROMs) are key enablers for
combining high fidelity and system models
Such high accuracy, fast-running models can be used for
many development purposes, including controller
software development
Bringing Aerospace best practices, to improve
development of automotive embedded systems

Optimizing Battery Cell, Module, Pack and Controls Design with Comprehensive Simulation

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Optimizing Battery Cell, Module, Pack and Controls Design with Comprehensive Simulation