L11: Batteries Mechanical and Electrical Layouts · L11: Batteries Mechanical and Electrical...
Transcript of L11: Batteries Mechanical and Electrical Layouts · L11: Batteries Mechanical and Electrical...
L11: Batteries Mechanical and Electrical Layouts
L11: 16-APR-2019
Lund University / LTH / IEA / AR / MVKF25 / 2019-04-16 2
Outlook
• Modules and modularity– Electric connections
– Ø18L650 battery back – Web tutorials
• Cells and technologies– Cylindrical, prismatic, Pouch – heat flow in cell
• Packs, Banks and packing topologies– Cooling integration
• Battery pack design
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Electric connection of cells
• Series [V] –parallel [Ah]connections
• Connection busbars and cables are for electric distribution but also part of heat generation and distribution
• Nickel plate + spot welding = healthy low resistance connections
• Soldering, mechanical bolted connections, …
Lund University / LTH / IEA / AR / MVKF25 / 2019-04-16 4
14s11p – 51.8V18.7Ah
• https://www.youtube.com/watch?v=8Xv8B93EoH0 Patreon
• Reusing batteries <1A (2-4 peak)
• Series path of paralleled pairs
• Soldered connections
• 2x2.5mm2 bus bars, 0.14mm2 fuse wire connections
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4s30p – 16.6V80Ah
• https://www.youtube.com/watch?v=NGp7cGBYOLc&t=203s
• Reusage, sorting, …
• 15x8 Cell holders & domains of parallel cells
• Net of spot welded Ni-stripes (0.15 mm thick)
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13s6p – 48V20Ah
• https://www.youtube.com/watch?v=Xoc4LIy5SnI Ebikeschool
• New batteries, sorted
• Hexagon fitted and glued cells
• Series connected stack of paralleled cells
• spot welded and soldered NI-stripes
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BPD:EM
18650 Li-ion
• Standard (size) cylindrical Li-ion cells ø18h65mm
• ?– Nortvolt Lingonberry
21.70
– NV INR21/70 E1 vs P1
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Sorting methods
• Sorting methods– Capacity and AC internal
resistance (C+ACIR)
– Electrochemical impedance spectroscopy (EIS)
– Voltage curve
– Cell dynamic parameters
– Cell thermal behaviour
• Dynamic parameters are in interest but improved SOC aging need to be studied before producing B-pack
Xiaoyu Li et. Al “A comparative study of sorting methods for Lithium-ion batteries”, ITEC Asia-Pacific, 2015
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Nickel connection strips, BMS
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Overview: BatPackDes
Battery Pack Design
Mechanical and electrical layout
Batteries thermal modeling
Battery management
Purpose, function, model Geometry, cell, module, pack
Cell design and thermal loads Cooling integration
Control and management (SOC) Usage and degradation (SOH)
BPD:intro
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Goals
• Design and dimensioning of battery pack based on suitable models
– evaluate suitable battery technologies, specify celland packing, electric and thermal termination
– battery development and energy managementsystems, predict state of charge, health, function, ..
– test battery compatibility to operating conditions, current waveforms Ageing model
Thermal model
Electrical model
BPD:intro
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Background A
• Vehicular application– Electrification improves energy
usage – hybrids
• use ICE at 35% instead of 10-20% efficiency
• Reuse deceleration energy for acceleration
– Pure renewable fuel/energy
• System view– Charging, static vs dynamic
– Compatability, AC current loading
Battery and Propulsion
BPD:intro
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Background C
Machine PE Battery cell
Peak power density (kW/L) 1.5‐6.6 3.7‐17.2 0.5‐9
Peak specific power (kW/kg) 0.5‐2.5 4‐16.7 0.2‐4
M. Yilmaz P.T.Krein 2013
BPD:intro
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PART-1: BPD.EMElectrical and mechanical layout
Function and realization
Performance chart
Cell construction and design
Pack specification
Characteristics and properties Models and tests
Cylindrical, prismatic, pouch design and realizations
Termination Modularity
BPD:EM
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Comparison of vehicle battery types
B. Sarlioglu et al, “Driving toward accessibility” IEEE 2017BPD:EM
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Comparison of battery cell types
B. Sarlioglu et al, “Driving toward accessibility” IEEE 2017BPD:EM
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Overview of cell producers for xEVs
• It is easier to find producer than product ;)
BPD:EM
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Vehicular application
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Energy storage for vehicular application
• Battery – most important, currently most expensive
• Battery technology – in its infancy, expectedly continues to mature, reducing price and size, increasing capacity
• 2010 the cost of an EV battery per kilowatt-hour (kWh) ranged from US$600 to US$1,105 (2010). Last five years has brought the estimated price near US$500/kWh.
• Vehicular requirement (apart from no cost): Range=energy capacity, Acceleration=Power
BPD:EMhttps://www.youtube.com/watch?v=2PjyJhe7Q1g
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Roadmap: from cell to pack
• Design– path from topology
sketching to practical realization
• Cell, Module, Pack/Bank• Battery = Energy storage
[Wh] & Power supply [W]– Applications: Vehicle/Grid– Technologies: Li-ion
• Battery cell– Geometries and
dimensions– Characteristics and
properties
• Cell “virtual” packing
• Electro-Thermal models
• Packing examples
• Thermal design– Cells, modules, backs
• Battery Management System
BPD:EM
Ageing model
Electrical model
current Thermal model
power
temperature voltage
DoD SoH
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Battery back design & sizing
• Number of series connected cells in strings
– Ns=Udc/Ucell
• Number of parallel connected strings
– Np=Energy/(Ns*[Wh/kg]*[kg])
– Np=Energy/(Ucell*”cell capacity”)
• Circuits– Electric, thermal, etc
– Protection, surge, over voltageand overheat
BPD:EM
• Self study from page 161 – example cell selection consequences
– 300 V * 100 A
– Pmax = 2*30kW
– P/E ratio 2 and 20
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Cylindrical, Prismatic, Pouch
• Hundred or thousands of series and parallel coupled cells to achieve the required power and energy
• Joining requirements: electrode-to-tab + case container
AnodeSeparator
Cathode
www.jmbatterysystems.comBPD:EM
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Energy Management vs Design
• A cross-road of different disciplines
• Multi-dimensional (analysis) & multi-objective (synthesis)
Construction Production
Energy Conversion
kg kW, kWh
Pack specification
Pack architecture
Pack design
Electrical power system
Module design
Electrical distribution system
System safety
BMS design
Module CU
CELL
BPD:EM
•Joining methods
and E, M, T criteria?
Information
Energy• Monitoring – measure what
is important
• Control – keep it optimal and constrained
• Diagnosis – keep battery cells healthy
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Specific energy and power• Specific energy
originates from material chemistry
– Capacity capability
• Specific power is related to material physics and production
– Internal power losses and thermal constrains –durability and safety
BPD:EMRagone plot
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Value chain for EV batteries
• From cell realization to recycling (excluding raw materials)
• Vehicle power (performance), energy (range) and integration (BMS)
Fig.Ref.: B. Averill, P. Eldredge, “General Chemistry: Principles, Patterns and Applications”BPD:EM
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BPD:EM
Lithium Battery Technologies
• Optimal performance and lifetime capacity
• Case sensitive: application vs cell configuration
Abbr Wh/kg
Lithium cobalt oxide LiCoO2 LCO
Lithium manganese oxide LiMn204 LMO 4.0V 114-159
Lithium iron phosphate LiFePO4 LFP 3.2V 114-138
Lithium nickel manganese cobalt oxide LiNiMnCo02 NMC 3.7V 93-171Lithium nickel manganese aluminum oxide LiNiCoAlO2 NCA
Lithium titanate Li4Ti5O12 LTO
R. Purkayastha, R.M. McMeeking, "A Linearized Model for Lithium Ion Batteries and Maps for their Performance and •What is and can be done?
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Cell material properties example
materialThickness
[μm]
Thermal conductivity
[W/mK]
Electrical conductivity
[S/m]
+ I collector aluminum 20 238 37.8e6
+ Electrode 106 1.58 (wet) 13.9 (wet)
Electrolyte wet
Separator 25 0.34 (wet)
- Electrode 111 1.04 (wet) 100 (wet)
- I collector copper 14 398 59.6e6
case 162 0.16
M. Yazdanpour, “A circuit-based approach for electro-thermal modeling of Lithium-Ion batteries”
•What dimensions what materials?
BPD:EM
• Explore the ”rolled” structure inside the battery cells in order to study loss generation and dissipation
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Cell construction
• Electrode arrangement: spiral wound jelly roll, stackedelectrodes, bobbin type
• Geometry: Cylindrical, Prismatic, Pouch, Button
www.toray-eng.com
• Components– Case: plastic (PET)
or metallic (steel, Al)
– Core=activecomponents+collectors, separator
– Terminals
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Prismatic Cells
• Some cell producers– Hitachi, Samsung-SDI,
Panasonic (Sanyo)
– Northvolt Cloudberry173.115, Lingonberry NV INP27/91/148 L1 vs E1
• PHEV2 format
Prismatic cell
L, [mm] W, [mm] T, [mm] M, [kg] U, [V] C,[Ah]p,
[W/kg]c,
[Wh/kg]Hitatchi-1 148 91 26.5 0.72 3.6 28 2300 140
SDI-1 37SDI-2 60SDI-3 94
BPD:EM
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Kokam’s SLPB cell
• SLPB – Superior Lithium Polymer Battery
• Pouch type improvedheat dissipation due to larger surfaces
• Example 240Ah 4.8kg cell
– Pheat=1.1kW @ 480A
– Acool=2x0.15 m2
– V=46.2x32.7x1.58 cm
Kokam.com
0 500 1000 1500 2000 250060
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SLPB160460330
specific power, pcell
[W/kg]
spec
ific
ener
gy,
wce
ll [W
h/kg
]
Kokam large cells
BPD:EM
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Specification list
LinkSource Sink
• Forced heating/cooling for battery back– Concepts, topologies, realization ideas, …
• Battery cell – Construction, properties, heat sources, thermal
loads, …
• Heat conductor– Thermal accessibility, thermal contacts, …
• Cooling plate– Realisation, performance, …
BPD:EM
BPD:TH
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Thermal design
• Methods, models, calculation examples for thermal design
• Practical realisation examples from some car manufacturers
Heat
Electricity
BPD:TH
CELL
PACK
SYSTEM
• Chemistry
• Geometry
• Properties
• Thermal interface
• Coolingintegration
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Thermal modelling
LinkSource Sink
• Models 1D, 2D, 3D analytic or numeric– Computation time vs accuracy, …
• Single cell, a module of cells, battery back – Specification of equivalent cell volume with specific losses, …
• Assembling, heat transport and temperature distribution– Mechanical assembly and thermal accessibility, thermal contacts
• Integration of active cooling circuits– Realisation, estimation of coolant flow and performance, …
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Thermal integration• Power semiconductor
example
• Direct cooling where it is most needed in order to minimize heat transport through the solids that causes interior temperature rise and uneven temperature distribution
• Consider the effects of thermal cycling and expansion
• Experiences from other electric drive components
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Cooling integration
• Cooling mechanisms
• Cooling flow determination
• Cooling duct and system design
• From rough design point of view – identify cooling surface and applied HTC on the surface
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Cell library• Connect geometry and power
capability into battery-pack layout
• Selected cell examples: cylindrical, prismatic, pouch
• This information is used for virtual packing and rough estimation on temperature rise and distribution
Manufacturer
configuration Geometry Voltage CapacitySpecific power
Weight
[mm] [V] [Ah] [W/kg] [g]Panasonic Cylindrical Ø18.5x65.3 3.6 3.2 120 48.5
Hitatchi Prismatic 148x91x26.5 3.6 28 2300 720Kokam Pouch 462x327x15.8 3.6 240 360 4780
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Cell “virtual” packing• For 300V there is need of 84 series
connected 3.6V cells
• First draft of 148x26.5 mm prismatic cell arrangement where 5 mm distance is left between the rows and groups of 7 cells
• First draft of ø18 mm 4 parallel cylindrical cell arrangement with cooling channel in between the cells
• Not only visualization but a parameterized model with coupling to finite element analysis (FEA)
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Battery pack with cylindrical cells• “Empty” space between cells
• Cross-flow through battery module– Narrow spacing – expectedly no
cooling
– Large spacing for sake of better cooling is often considered impractical
• CFD vs “fast” design approaches
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Battery back with prismatic cells
• Temperature homogenization analysis
• Analysis of thermal runaway
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Battery pack with pouch cells• Coupled electro-thermal
FE+model order reduction (MOR) simulation compared to thermographic images
– A reduced order model (ROM) based on singular value decomposition (SVD)
• Direct air-cooled Li-ion pouch battery cell in order to improve the understanding (modelling) and practical realization of battery module
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Chevy 104kW 20kWh• GM Volt and Spark EV use thin
prismatic shaped cooling plates in between the cells with the liquid coolant circulating thru the plate.
• The Volt cooling scheme is very effective from a cooling point of view but it is complicated. The cells are encased in multiple plastic frames
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Tesla S 285kW 70kWh• Tesla snakes a flattened
cooling tube thru their cylindrical cells resulting in a very simple coolingscheme with very few points for leakage.
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BWM i3 125kW 21-33kWh
• The BMW i3 cools the bottom of the battery case with refrigerant eliminating the liquid coolant entirely.
• New energy dense lithium ion cells (50% more)
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Integration example by BMW
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Integration example by Tesla
• 60kWh, 352V, 14 modules, 6216 cells in groups of 74=6x14
• 85kWh, 402V, 16 modules, 7104 cells
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Integration example by Tesla
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Accommodation of cylindrical cells
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• Single stage heat transfer insufficient hA vs UA
Cool-plate and coolant
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Heat transfer mapping
• Driving parameters for cooling P=f(out,Q) at in
• Flow (Re) and coolant (Pr) characterization
• Heat transfer – correlations (Nu) and – coefficient h
• Wall and winding temperature• Pressure across cooling
channel– Power for supply
• Expected cooling power P=f(w,Q) at in
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B. Sundén, “Introduction to Heat transfer”
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Thermal analysis of cell assembly
• Geometric data– Defined by German standard
DIN 91252
• Heat transfer inside the cell
– From cell to module and pack
– Cell = Jelly-roll (heater) + carrier (assembly)
• Heating power – Worst case P=I2Ro=50W
Hitachi 3.6v 35Ah 0.8mΩ@10A155x27x118 incl terminals 810g
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Thermal accessibility of a cell
• Available thermal connection areas
– Large long sides2x134cm2 but low thermal conductivity
– Sides, lateral sides2x24cm2 and Bottom side39cm2
• Bottom and short sides have expectedly betterinherit thermal contact
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Inside a battery cell
• Cell dimensions are known, jelly-roll geometry only guessed
• Heat conductivity defined in-plane and cross-plane for whole cell unit and jelly roll (including heat capacity)
• Important part for thermal models are termination and equivalent jelly-roll
DIN SPEC 91252:2011Lundgren et al 2016
H. Lundgren et al, ”Thermal Management of Large-Format Prismatic Lithium-Ion Battery in PHEV Application”
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Surface temperature response
• Thermal vs electric power extraction and comparison
• Thermal conductivity– Through-foil
0.95W/mK– Along foil 30.8 W/mK
H. Lundgren et al, ”Thermal Management of Large-Format Prismatic Lithium-Ion Battery in PHEV Application”
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2D FE over cross-sections
CaseQbase
[W]Qlateral
[W]max
[oC]
1 50 0 60
2 33 17 55
3 21 29 44λcell=1 W/mK
λcell=20 W/mK
Qv=140W/dm3, surf=30oC
6054484236
Temperature , [C]
30
2
1
3
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Observations A
• Battery cell– P=50 W heating, 1/R=0.6 0.5 0.28 K/W, Δ=30 25 14 K
• Heat conductor– Ideal 1/R=0 K/W, Δ=0 K
• Cooling plate– Ideal fluid=wall=surf=30oC
LinkSource Sink
50 W per cell
surf=30oC wall=30oC fluid=30oCcell= surf+Δ
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Realization A
• Mechanical assembly in “cross” plane direction
• Thermal enhancement both in plane directions
– Lateral clamp or forcing plate
– Battery to base contact
• ..
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Cell clamped into heat conductor
CaseQbase
[W]Qlateral
[W]max
[oC]
1 34 16 51
2 32 18 54
3 27 23 72
Qv=140W/dm3, surf=30oC
6054484236
Temperature , [C]
30
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heig
ht,
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Cell linked to cool-plate
CaseQbase
[W]Qlateral
[W]max
[oC]
1-30 36 14 53
2-h1 35 15 68
3-h2 35 15 148
Qv=140W/dm3, fluid=25oC
6054484236
Temperature , [C]
30
h1=1000W/Km2 wall Δwall=15oCh2=200W/Km2 wall Δwall=95oC
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Transient heating
• 5 minutes between the frames (FEMM transient HT)
• Hot side of the scale (usually presented in between 20-30oC)
• One dominating heat capacitance only
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Summary
• Battery cell– Δb=30 25 14 K @ 50W – actual load is lower
• Heat conductor– Insufficient thermal contact 0.1 mm air Δc=20K @ 50W
• Cooling plate– Insufficient heat transfer h2=200W/Km2 wall Δwl=95oC
LinkSource Sink
50 W per cell
surf= wall+Δc wall= fluid+Δw fluid=30oCcell= surf+Δb
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Thermal design, control and management
• .J. Li, Z. Zhu, “Battery Thermal Management Systems of Electric Vehicles”, MSc Chalmers 2014
• 29.5/17.7 kWh &1700/270 kg