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

500us 0

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

Smal

l Sca

le

Larg

e Sc

ale

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

eeee j

F

tcD

t

c

1)(

Impact of Discharge Rate on Capacity Charge Discharge Cycles Temperature 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

Cu

rre

nt

(A)

Time (s)


Cell Level – CFD Thermal

Temperature Distribution


Cell Level –Electro-Thermal

Current Density Cathode 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

X. Hu, L. Collins, S. Stanton, S. Jiang, "A Model Parameter Identification Method for Battery Applications", SAE 2013-01-1529.

Battery Pack ECM

Simulation Results

16 © 2014 ANSYS, Inc. August 21, 2014 ANSYS Confidential X. Hu, L. Collins, S. Stanton, S. Jiang, "A Model Parameter Identification Method for Battery Applications", SAE 2013-01-1529.

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

LTI t 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 Model Embedded Controller

Control Software Development

C code

Desig

n Im

plem

entatio

n


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

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