battery simulation with ansys software – case...

© 2011 ANSYS, Inc. November 27, 2014 1

Battery Simulation with ANSYS Software – Case Studies

Sandeep Sovani, Ph.D. Manager, Global Automotive Strategy ANSYS Inc, Ann Arbor, MI, USA September 30, 2011

Xiao Hu, Ph.D. Lead Technical Services Engineer ANSYS Inc, Ann Arbor, MI, USA


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 2,000 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

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U.S. Department of Energy (DOE) major portion of $7M award given to ANSYS – General Motors – Esim

For the development of computer-aided software design tools to help produce the next generation of electric drive vehicle (EDV) batteries

ANSYS – General Motors – Esim Collaboration for Battery Software


Battery Simulation

Old Paradigms Single Component Simulation Single Physics Few design points simulated

New Paradigms Multidomain Simulation (Component and System) Multiphysics Simulation (Flow, thermal, structural, electrical, electrochemistry) Extensive Design Exploration

Simulation practices common in today’s automotive engineering are not sufficient for disruptive technologies such as EV/HEV batteries

New paradigms apply to disruptive technologies


New Paradigm 1 – Multidomain Simulation

Phenomena at one level affect those at other levels and need to be simulated in simultaneous co-simulation

Electrode Level

•Electrode layout •Manufacturing process development •Life

Molecular Level

•Material innovation •Material selection

Cell Level •Charging, dischar-ging profiles •Heating •Safety under abuse •Swelling, deformation

Pack Level •Thermal Mgmt •BMS Logic •Safety •Durability •NVH •EMI/EMC

Powertrain and Vehicle Level

•System Integration

Smal

l Sca

le

Larg

e Sc

ale


Thermal

High fidelity 3D physics solvers

Co-Simulation and Model Extraction Multidomain system

simulation software

Fluid Electro- chemical

Structural Electrical

ANSYS Multidomain Simulation New Paradigm 1 – Multidomain Simulation

Fully integrated component and system level simulation tools


Newman’s 1D Electrochemistry Model Electrode Level

Manufacture Material selection Electrochemistry

Starting from the electrode level . . .

3D Electrochemistry Simulation

Multidomain Simulation


Multidomain Simulation – Electrode Level ANSYS Case Study – 3D Electrochemistry Modeling


Multidomain Simulation – Electrode Level

Li concentration in electrodes during discharge

ANSYS Case Study – 3D Electrochemistry Modeling


Multidomain Simulation – Electrode Level ANSYS Case Study – Pseudo 2D Electrochemistry Newman Model


Multidomain Simulation – Electrode Level

• Electrochemical Kinetics • Solid-State Li Transport • Electrolytic Li Transport

• Charge Conservation/Transport • (Thermal) Energy Conservation

Results from Simplorer Results from Newman

( ) Liee

ee jF

tcDtc +−

+∇⋅∇=∂

∂ 1)(ε

ANSYS Case Study – Pseudo 2D Electrochemistry Newman Model


ANSYS Simplorer’s Results

x=0

x=Lp+Ls+Ln x=Lp+Ls

x=Lp

1/10 C 1/2 C 1 C 2 C 4 C 6 C 8 C 10 C

•Reference: Long Cai, Ralph E. White, Journal of Electrochem. Soc., 156 (3), A154-A161 (2009)

White et al’s Results

Multidomain Simulation – Electrode Level ANSYS Case Study – Pseudo 2D Electrochemistry Newman Model – Quantitative Validation


ANSYS Simplorer’s Results White et al’s Results

•Reference: Long Cai, Ralph E. White, Journal of Electrochem. Soc., 156 (3), A154-A161 (2009)

Multidomain Simulation – Electrode Level ANSYS Case Study – Pseudo 2D Electrochemistry Newman Model – Quantitative Validation


. . . incorporating electrode level effects into the cell level . . .

Cell Thermal Model with Electrochemistry Cell Level Electrical Model Heat Generation Abuse Nail Penetration Crush



- Newman & Tidemann (1993); - Gu (1983) ; - Kim et al (2008)*

( ) J=∇⋅∇ φσ

)()( TfUYJ np −−= φφ

Cathode Anode

Current Current

ip= Current Vectorsat Cathode plate in= Current Vectors

at Anode plate

J = Current DensityJ (t, x, y, T )

Cathode Anode

Current Current

ip= Current Vectorsat Cathode plate in= Current Vectors

at Anode plate

J = Current DensityJ (t, x, y, T )

Transfer current

U and Y are derived from experimentally obtained polarization curve, dependent on Depth of Discharge (DOD) & Temperature

A model based on the work of:

* Reference: U. S. Kim, C. B. Shin , C. S. Kim, “Effect of electrode configuration on the thermal behavior of a lithium-polymer battery”, Journal of Power Sources 180 (2008) 909–916.

Multidomain Simulation – Cell Level ANSYS Case Study – Pouch Cell Thermal Simulation


Geometry & Mesh

Temperature Current Density

Multidomain Simulation – Cell Level ANSYS Case Study – Prismatic Cell Thermal Simulation


ANSYS Simplorer Battery Electrochemistry Model ANSYS FLUENT Battery CFD Model

Heat Dissipated

Temperature Negative Electrode

Positive Electrode

Separator

δs δn δp

x=0 x=L

Multidomain Simulation – Cell Level ANSYS Case Study – Cell Level Thermal Simulation Coupled with Electrode Level Electrochemistry Simulation

Electrode level electrochemistry is simulated simultaneously with cell level thermal simulation. Electrochemistry simulation provides local heat generation to the cell thermal simulation. The cell thermal simulation returns local temperature values to the electrochemistry simulation.


Ref: Hu et al. “A Novel Thermal Model for HEV/EV Battery Modeling Based on CFD Calculation”, IEEE Energy Conversion Congress and Expo, Atlanta, Sep 12-16, 2010

Module Level Thermal Mgmt BMS Crash, Crush Durability NVH EMI/EMC

Detailed module level simulation and reduced order model extraction

. . . incorporating cell level effects into the module level . . .



Multidomain Simulation – Module Level ANSYS Case Study – Paper presented by Magna Steyr at ANSYS European Automotive CFD Conference


Multidomain Simulation – Module Level ANSYS Case Study – Numerous Publications from NREL Describing ANSYS Simulations



Battery Electro-Thermal Modeling


Cooling and Preheating of Batteries in Hybrid Electric Vehicles

Comparison of heating rates for two rectangular batteries with different aspect ratios (energy input of 6.62 Wh/kg in 2 min)



Two Publications By Delphi and Ford

Multidomain Simulation – Module Level ANSYS Case Study – Two Collaborative Publications from Ford and Delphi Describing ANSYS Simulations


Full Hybrid Electrical Vehicle Battery Pack System Design, CFD Simulation and Testing

Velocity contours of airflow through the brick, inlet and outlet plenum

Airflow path into the battery pack Airflow path and air outlet

Front view of the pack with the two bricks assembled and inlet busbar

Multidomain Simulation – Module Level ANSYS Case Study – Two Collaborative Publications from Ford and Delphi Describing ANSYS Simulations


Multidomain Simulation – Module Level ANSYS Case Study – Several Papers Co-Authored by ANSYS and General Motors on Model Order Reduction


Motivation of Using Model Order Reduction – CFD as a general thermal analysis tool is accurate but • Can be expensive for large system level repeated transient CFD analysis • Can be cumbersome to couple with electrical circuit model for large system

analysis



Linear Time Invariant (LTI) Method Used to Drastically Reduce Runtime of Long Transient Simulations

State space model gives the same results as CFD. State space model runs in less than 5 seconds while the CFD runs 2 hours on one single CPU.

1. X. Hu, S. Lin, S. Stanton, W. Lian, “A Novel Thermal Model for HEV/EV Battery Modeling Based on CFD Calculation” IEEE Energy Conversion Congress and Expo, Atlanta, Sep 12-16, 2010 2. X. Hu, S. Lin, S. Stanton, W. Lian, “A State Space Thermal Model for HEV/EV Battery Modeling", SAE 2011-01-1364



The LTI Method works for moderately non-linear cases as well

Non-linear CFD: Ideal gas law plus temperature dependent properties are used. Full Navier-Stokes equations are solved

LTI: Assumes the system is linear and time invariant.

A speed-up factor of 10,000 is observed. Huge time saving.



• E.g. 60 Cells connected in matrix pack

• Packs are connected in matrix to final configuration

Pack Level Thermal Mgmt BMS Crash, Crush Durability NVH EMI/EMC

Individual Cells

Module

Pack

. . . incorporating module level effects into the pack level . . .

System Model of the Pack



• 60 Cells connected in matrix pack

• Packs are connected in matrix to final configuration

5 cells

• Peak voltage: 16 V (4 cells in series) • Peak current: ~3.25 Amp (15 cells in parallel)

– 0.4 Amp for single battery case – And yet runtime is ~doubled – Estimated life: 0.4/(3.25/15)x8000 sec

without rate factor consideration

Multidomain Simulation – Pack Level ANSYS Case Study – Pack Level Circuit Model


Battery model incorporated into powertrain system with traction motor controls

. . . incorporating the pack model into powertrain level simulations


System Integration



Multi-disc clutch Torque limiter Linear Coupling Drive shafts

Alternator/inverter Perm. Mag. Motor Solid-state Controller Solid-state driver chips

Multidomain Simulation – System Level ANSYS Case Study – Battery in Control System with Motor Controller


Tight interplay of multiple physics in a battery

Old one-physics-at-a-time simulation approach does not work for batteries

New Paradigm 2 – Multiphysics Simulation

Thermal Fluid Dynamics

Electrical Electrochemical

Explicit Structural

Fatigue

Vibration


Electrode Level

•Electrochemistry •Life models •Thermal and Electrical Field Solvers

Molecular Level

•Molecular dynamics

Cell Level •Thermal, Electrical, Fluid Solvers •Structural Implicit and Explicit Solvers

Pack Level •Thermal, Electrical, Fluid Solvers •Structural Implicit and Explicit Solvers •Circuit models •EMI/EMC Solver


•System and Component Co-Simulation

Battery issues involve multiple physics at each stage



Fluids

Electrical CAD

Import

Structural

Post- process

Meshing

Magnetic

Workflow

Design Points

Thermal

ANSYS Multiphysics


All loading conditions can be simulated simultaneously . . . . . . as in the real environment • Current, Power Profile • Transient Drive Cycles • Heat Generation/Dissipation • Cooling Flow • Structural Durability • NVH • Crash, Abuse • EMI, EMC • etc…

Study interactions/trade-offs • E.g. electrical heating


Multiphysics Simulation

Battery Electrical Model

Cell 4

Cell 5

Cell 6

Cell 1

Cell 2

Cell 3

Battery Cooling Flow and Thermal CFD

Model

Heat Dissipated

Temperature

ANSYS Case Study – Electrical, Thermal, Fluids – Multiphysics Co-Simulation of a Module


Heat Dissipated

Temperature

Heat dissipation

Discharge curve

Temperature contours


ANSYS Case Study – Electrical, Thermal, Fluids – Multiphysics Co-Simulation of a Module


Electrical circuit and thermal circuit are coupled • Includes Positive Temperature Coefficient (PTC)

* Reference: L. Gao, S. Liu, and R. A. Dougal, “Dynamic lithium-ion battery model for system simulation,” IEEE Trans, Compon. Packag. Technol., vol. 25, no. 3, pp. 495-505, Sep. 2002

Implemented using VHDL-AMS ANSYS Simplorer® Model with PTC and 3 T Nodes

PTC and Battery Temperature Normal

Voltage Discharge with a load of 10 Ω

Discharge with a load of 2 Ω

PTC and Battery Temperature Overloading

Voltage


ANSYS Case Study – Electrical, Thermal, Network Model – ANSYS Multiphysics Simulation Described by Gao et al*


Temperature Distribution Current Density Distribution

Structural Deformation, Fatigue Life


ANSYS Case Study – Electrical, Thermal, Structural – Multiphysics Co-Simulation of Busbars


• Electrical circuit and Foster network are coupled

• Electrical circuit provides power to Foster network

• Foster network provides temperature to electrical circuit

Battery1 Heat Temperature1 Temperature2

Temperature3

Battery2 Heat

Battery3 Heat LTI

Electrical/thermal interaction


ANSYS Case Study – Electrical Circuit and Thermal Foster Network Model – Multiphysics Simulation of a Li-Ion Battery Module


0

0

0

0

0

00

CONST

H00RT_LRT_S

CT_LCT_SIBattCcapacity

Rseries

VOC

E1

R1

C1 I7C2 C3

R2 R3

CONST

H01

E2

R5

C4 I8C5 C6

R6 R7

CONST

H02

E3

R9

C7 I9C8 C9

R10 R11

CONST

H03

E4

R13

C10 I10C11 C12

R14 R15

CONST

H04

E5

R17

C13 I11C14 C15

R18 R19

CONST

H05

RLoad

SIMPARAM1

Qcell1Qcell2Qcell3Qcell4Qcell5Qcell6

Tambien

Temp_block_1Temp_block_2Temp_block_3Temp_block_4Temp_block_5Temp_block_6

0.00 2000.00 4000.00 6000.00 8000.00Time [s]

300.00

310.00

320.00

330.00

340.00

350.00

Y1

[kel

]

Curve InfoU1.Temp_block_1

TR

U1.Temp_block_3TR

U1.Temp_block_5TR

Voc=f(SOC, U1.Temp_block_1)


ANSYS Case Study – Electrical Circuit and Thermal Foster Network Model – Multiphysics Simulation of a Li-Ion Battery Module



ANSYS Case Study – General Motors and ANSYS Collaborative Publication Describing Electrical, Thermal, Fluids Multiphysics Battery Modeling


Variable x

Vari

able

y

Variable x

Vari

able

y

Design Points Evaluated

Old Paradigm

Simulation of only a few design points

New Paradigm 3 – Extensive Design Exploration

Design Space Design Space

New Paradigm

Evaluation of entire design space


ANSYS WorkBench and DesignXplorer A platform engineered for extensive design exploration

• Design of Experiments • Six Sigma Analysis • Goal Driven Optimization • What-If Analysis • Deterministic Analysis • Variational Technology • Robust Design

Automated Tool Set

High Performance Computing Distributed Solve Options

Extensive Design Exploration


Extensive Design Exploration ANSYS Case Study – NREL Publication Describing ANSYS Simulation for Six-Sigma Analysis of Battery Thermal Management


Input with Variations • Gap Thickness • Cell Resistance • Flow Rate

Outputs with variations • Max temperature • Differential temperature • Pressure drop

Extensive Design Exploration ANSYS Case Study – NREL Publication Describing ANSYS Simulation for Six-Sigma Analysis of Battery Thermal Management


Questions

Thank You

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