European GT Conference - gtisoft.com€¦ · Agenda 02.10.2019 01 Introduction Cell Calibration...
Transcript of European GT Conference - gtisoft.com€¦ · Agenda 02.10.2019 01 Introduction Cell Calibration...
Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
European GT Conference
M.Sc. Dennis Schier / Dr.-Ing. Frank Seifert
Frankfurt, October 2019
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Agenda
02.10.2019
Introduction01
Cell Calibration with GT-AutoLion
Thermal Model of the Battery Pack03
02
Results04
Conclusion05
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
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Introduction
• Rheinmetall Automotive is traditionally strong in the market of conventional drive trains
• Expansion of the traditional product portfolio with products for electric and hybrid drive trains
• become a competent partner for electric drives, battery packs and power electronics
Motivation:
• Development of a simple tool for the evaluation of (scalable) battery pack concepts
• Fast reaction for customer inquiries
Requirements:
• Low calibration effort based on 3D CFD
• Cell Temperature error should not exceed 1K on average
• Gradient of the individual cell temperatures across the battery pack must be consistent
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
02.10.2019
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Calibration for stationary
Cell Temperature Distribution
Simulation Workflow
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
Geometry
Preprocessing
Geometry Translation into
Thermal Masses Model
Model Parametrization
for Thermal Distances
Cell Calibration
� Comparison of stationary and transient results with 3D CFD
� Comparison of cell model with test results
� Validation with test results
� Calculation of temperature distribution for real drive cycles
02.10.2019
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Agenda
02.10.2019
Introduction01
Cell Calibration with GT-AutoLion
Thermal Model of the Battery Pack03
02
Results04
Conclusion05
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
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GT-AutoLion | Cell Description
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
Cell Characteristics:
• Prismatic Cell
• Stacked Electrodes
• LiFePO4 / Graphite
• 72 Ah Capacity
• 3.2V Nominal Voltage
• 2C max. Constant
Current
Create AutoLion model to simulate cell behaviour:
Available Data for model creation and calibration:
• CT-Scan
• Official Datasheet
• Capacity Test for 0.05C (Discharge)
• Capacity Test for 1/3C, 1C and 2C (Discharge)
Electrical Data
Thermal Data
Model
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GT-AutoLion Template
Cell Dynamics Calibration
Optimization
OCV Calibration
GT-AutoLion | Calibration Workflow
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
CT-Scan Official Datasheet
Capacity Tests for 0.05C
Capacity Tests for 1/3C, 1C and 2C
• Geometry Parameters
• Capacity Loading | N/P Ratio
• First Charge/Discharge Capacity
• OCV@100% SOC
• Contact Resistance
• Diffusivity Multiplier
• Heat Transfer Coefficient
GT-AutoLion Template Parameters
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GT-AutoLion | Calibration Results
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
• Calibration results for capacity discharge tests
OCV|1/3C|1C|2C
• Maximum error about 1% for voltage values
• Capacity fit for all cases (except 2C)
• No calibration of charging tests so far
� Template can be integrated into complete Battery
System Model
� Heat flow from cells can be extracted and fed into
Thermal Model
02.10.2019
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Agenda
02.10.2019
Introduction01
Cell Calibration with GT-AutoLion
Thermal Model of the Battery Pack03
02
Results04
Conclusion05
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
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Profile � Aluminum
Cell Fixing - Plastic
Profile
�Caoutchouc
Thermal Model (TM) | Battery Setup
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
Prismatic Cell
� Lithium Ion
Case � Aluminum
• 48 Volt Application
• Battery Capacity 15kW-h
• Two chambers (symmetrical)
• 64 prismatic battery cells
• Passive cooling
Backfilling
Material
(Compound) �
Synthetic Resin
Busbar � Copper
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TM| Geometry Preparation and Modelling
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
• Preparation of the CAD geometry in SpaceClaim
• Simplification of the CAD model
• Definition of a thermal resistance between the cells instead of a thermal
mass for the casting compound
• Consideration of the anisotropy of the battery cell
• Control of the heat flows in the battery pack
Sectioning of the casting compound into
5 thermal masses1 2
3
4
5
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Intermediate
material
• Anisotropic
material properties
• Coordinate
direction
Thermal resistance between all cells
λλλλ
Thermal
conductivity
xy
z
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TM| Battery Pack with Thermal Masses
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
One Chamber of the Battery Pack
Battery Cell
Case
Air
Volume
Ambient
Conditions
Cover Plate
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Part of the
Backfilling
Material
Busbar126 thermal masses
Model with nearly 1000 possible
calibration Parameter for “DtMC”
Optimization:
17 Parameter for “DtMC” in use
to keep it “as simple as possible”
“DtMC”: Distance to Mass Center
CFD Analysis
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8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1
37.3 37.7 37.9 38.0 38.0 38.0 37.9 37.6 4 37.4 37.7 37.8 37.9 38.0 37.9 37.9 37.6 4
37.6 38.1 38.4 38.5 38.6 38.5 38.3 38.0 3 37.6 38.1 38.4 38.5 38.5 38.4 38.3 37.9 3
37.7 38.1 38.4 38.5 38.5 38.5 38.3 37.9 2 37.6 38.1 38.4 38.5 38.5 38.4 38.3 37.9 2
37.4 37.7 37.9 38.0 38.0 38.0 37.9 37.6 1 37.4 37.8 37.9 38.0 37.9 37.9 37.8 37.6 1
left side of the battery pack - 3D CFD Simulation left side of the battery pack - GT-Suite Simulation
TM | Model Calibration
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
• Calibration of stationary load points with results from 3D CFD
for different cases
• Variation of stationary cell heat source
• Variation of stationary ambient conditions
• Optimization for “Case Sweep and Cross-Case Studies”
• Goal: average cell temperature calibration error ≤ 1K
• Result: max. ave. error about 0.25K / symmetry between chambers
• Transient results for a 7-Day-Cycle with calibrated model
• Changing BC´s for HTC, temperature and heat source
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8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1
37.4 38.1 38.4 38.6 38.6 38.5 38.3 37.8 4 37.5 38.2 38.5 38.6 38.8 38.7 38.5 38.0 4
37.9 38.8 39.3 39.5 39.5 39.4 39.1 38.3 3 38.1 39.1 39.5 39.7 39.8 39.7 39.3 38.6 3
37.9 38.8 39.2 39.4 39.5 39.4 39.0 38.2 2 38.1 39.1 39.5 39.7 39.8 39.7 39.3 38.6 2
37.4 38.1 38.4 38.5 38.6 38.5 38.2 37.6 1 37.6 38.3 38.6 38.7 38.7 38.6 38.4 38.0 1
left side of the battery pack - 3D CFD Simulation left side of the battery pack - GT-Suite Simulation
8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1
44.4 45.9 46.6 47.0 47.0 47.0 46.6 45.5 4 44.6 46.0 46.6 46.9 47.2 47.0 46.6 45.6 4
45.6 47.6 48.6 49.1 49.2 49.0 48.4 46.9 3 45.4 47.7 48.7 49.2 49.3 49.0 48.2 46.5 3
45.6 47.6 48.5 49.0 49.2 48.9 48.3 46.7 2 45.5 47.7 48.8 49.2 49.3 49.0 48.2 46.5 2
44.6 46.0 46.6 46.9 47.1 46.9 46.5 45.3 1 44.6 46.2 46.9 47.1 47.0 46.8 46.4 45.5 1
left side of the battery pack - 3D CFD Simulation left side of the battery pack - GT-Suite Simulation
3D CFD3D CFD GTGT
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TM | Battery Pack with Thermal Masses and GT-AutoLion
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
• Electrochemical integration with GT-AutoLion � validated model
• Build up of the battery cell arrangement and electrical flow
• 4 cells in parallel and 16 cells in series (4p16s)
• Transfer of dissipated heat from battery cell and ave. temperature from thermal mass
Temperature from
thermal masses to
the cells
4 cells in parallel 4 cells in parallelDissipated heat
rate from the
cells to the
thermal masses
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Current profile
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Agenda
02.10.2019
Introduction01
Cell Calibration with GT-AutoLion
Thermal Model of the Battery Pack03
02
Results04
Conclusion05
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
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Results | 1C Discharge Battery Pack
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
Boundary Conditions
• Measurement for 1C Discharge
• Battery cell initial temperature 31-33°C
• Ambient temperature 25°C
• Start-SOC = 0.85
Results
• The gradient of the temperature characteristic is
similar
• Note: model calibration only with 3D CFD!
• Simulation results for the 1C discharge match
the test results very well
• For the case of battery charging, there are
currently deviations between simulation and
measurement
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Different initial
temperature
Test 1C: Max TCell
Test 1C: Min TCell
Sensor
Position
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Agenda
02.10.2019
Introduction01
Cell Calibration with GT-AutoLion
Thermal Model of the Battery Pack03
02
Results04
Conclusion05
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
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Conclusion
• GT-AutoLion Cell Calibration successful according to recommended workflow by GT
• Small Error for discharging curves after calibration
• GT suitable for thermal management modeling
• Easy build-up of a battery model with passive cooling
• First verification with battery pack measurements shows good matches
• The model fulfills the defined requirements
• Further investigations are necessary
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
02.10.2019
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Thanks to
GT Conference 2019 – Evaluation of the Thermal Behavior of a 48V EV Battery with Passive Cooling
02.10.2019
Peter Stopp / Vehicle & Electrification
Dr. Dig Vijay / Thermal Management
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