Research Repot on A123 Battery Modeling

8/13/2019 Research Repot on A123 Battery Modeling

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Research Repot on A123 Battery

Modeling

Task 4 Members:

Faculty: Dr. Mo-Yuen Chow, Dr. Srdjan LukicResearch Assistants: Lei Wang, Arvind Govindaraj
http://www.ncsu.edu/


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Future Renewable Electr ic Energy Delivery and Management System s Center

Presentation Outline

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Research Objectives

Battery Properties

Battery Model

Future Research


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Research Objectives

Battery Modeling

Develop Charging Algorithms

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Research Objectives

Overview of battery properties

Battery Model

Future Research


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PHEV Battery Operation Modes

Charge-depleting mode: vehicle uses battery poweruntil SOC reaches a predetermined level

Charge-sustaining mode: uses both battery and engine

power

Blended mode: charge-depleting mode with enginepower to reach high speed

Ex. 90% of time discharging,

10% charging

Ex. 30% discharging, 70%

charging


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A123 Lithium Ion ANR26650M1

ANR26650M1 Datasheet AUGUST 2008

25C, C/30

< 20A tested

SoH


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A123 Lithium Ion ANR26650M1

Not available

Maximum discharge: 70A

Model may fail at high discharge current due

to irregular shape of the discharge curve

Operating range: -30c to 60c

Performance under different temperatures

was not testedDischarge curve shape changes at extreme

temperatures, thus may not be described by

model equations

First Step: Have a model that satisfies the nominal condition



Quantify Battery

State of Charge (SoC): 100% > SoC > 0%

SoC = (remaining capacity) / (capacity of fully chargedbattery)

SoC = (remaining capacity) / (Total amount of usablecharge at a given C-rate)

SoC = (CnQb) / Cn Cn: nominal capacity Qb: net discharge

Remaining Capacity Usable Capacity

Usable capacity depends on the cutoff voltage

Usable capacity depends on the age of the battery

Capacity of fully charged battery Total amount of usable

charge at a given C-rate Cn (C/30)

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Usable Capacity

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0 1000 2000 3000 4000 5000 6000 7000 80002.6

2.8

3

3.2

3.4

3.6

3.8

4

Time (s)

Voltage

(v)

T=7738s

Discharge Rate = 1A7738s x 1A / 3600s = 2.149Ah

0 200 400 600 800 1000 1200 1400 16001.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

Time (s)

Voltage

(v)

Discharge Rate = 5A

1537s x 5A / 3600s = 2.136Ah

T=1537s

0 100 200 300 400 500 600 700 8001.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

Time (s)

Voltage

(v)

Discharge Rate = 10A

1389s x 10A / 3600s = 2.1215Ah

T=1389s

0 50 100 150 200 250 300 350 4001.8

2

2.2

2.4

2.6

2.8

3

Time (s)

Voltage

(v)

Discharge Rate = 20A

683s x 20A / 3600s = 2.098Ah

T=683s



Usable Capacity vs Discharge rate

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2.06

2.11

2.16

2.21

2.26

2.31

0 5 10 15 20 25

Rated Capacity at 2.3Ah (using C/30

discharging rate)



Quantify State of Health (SoH)

Full Discharge Test (SOH)SoH = (measured capacity) /(rated capacity)

1 > SoH > 0 A battery is at its end of lifetime at SoH of 0.8 .(EnergyInstitute Battery Research Group)

Increase in internal resistance resulting active powerloss

Increase in self discharge

Counting charge/discharge cycles

Voltage drop during initial discharge

Two-Pulse Load Test

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State of Function (SoF)

Capability of the battery to perform a specificduty which is relevant for the functionality of a

system powered by the battery.

For example: Use 20A to discharge a battery

after 683s battery reaches the cutoff voltage 2v Battery still has the capacity left to be discharged by 10A

SoF is a function of the batterys SoC, SoH and

operating temperature.

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Research Objectives

Battery Properties

Battery Model

Model results and analysis

Future Research



Discharging Results

0 2000 4000 6000 8000 10000 12000 14000

1.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

3.8

1

2

3

4

51A

0 500 1000 1500 2000 2500 3000

1.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

1

2

3

4

5

5A

0 200 400 600 800 1000 1200 1400

1.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

1

2

3

4

5

10A

0 100 200 300 400 500 600 700

1.8

2

2.2

2.4

2.6

2.8

3

3.2

1

2

3

4

5

20A



Discharging Results - Average

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0 1000 2000 3000 4000 5000 6000 7000 80002.6

2.8

3

3.2

3.4

3.6

3.8

4

Time (s)

Voltage

(v)

0 200 400 600 800 1000 1200 1400 16001.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

Time (s)

Voltage

(v)

0 100 200 300 400 500 600 700 8001.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

Time (s)

Voltage

(v)

0 50 100 150 200 250 300 350 4001.8

2

2.2

2.4

2.6

2.8

3

Time (s)

Voltage

(v)



Temperature vs Time

Temperature vs. Time

0

5

10

15

20

25

30

35

40

45

0 5 10 15 20 25 30 35 40 45

Time (s)

Temperatur

1A

5A

10A

20A


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Constant Current Discharging

@ 20A, 10A, 5A, 1A

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 11.5

2

2.5

3

3.5

4A123 High Power Lithium Ion ANR26650 Cell Discharge Curves

R2_01A = 0.99

R2_05A = 0.97

R2_10A = 0.93

R2_20A = 0.85

Y: observed dataF: model data



Voltage Error: Actual voltageestimated

0 2000 4000 6000 8000 10000 12000 14000-0.14

-0.12

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

1A:


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Model 20% - 80% of SOC

At a low state of charge: nearly all the charging

current is absorbed by the chemical reaction.

Above 80% of SOC, more and more energy

goes into heat.reduce current for the last 20%


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Model output: Smooth line

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0 2000 4000 6000 8000 10000 12000 140001.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

3.8


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Measured

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4000 4200 4400 4600 4800 5000 5200 5400 5600 5800 60003.23

3.235

3.24

3.245

3.25

3.255

3.26

3.265

3.27

Zoomed in


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Interval Discharge

5A for 60s & 20A for 30s

0 100 200 300 400 500 600 700 800 9001.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

Time (s)

Voltage

(V)

Experimental data

Model output

Purpose: When driving, different discharging currents are applied to the battery


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Hysteresis

Hysteresis slowly changes as the cell

is charged or discharged

Hysteresis is considerably larger at

low temperatures.


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Modeling hysteresis effect

constant tunes the rate of decay

M is a function that gives the maximum polarization due to hysteresis as a function of

SOC and the rate-of-change of SOC.


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Relaxation effect

If a cell is pulsed with current, it takes time for thevoltage to converge to its steady-state level.Relaxation effect may be implemented as a low-passfilter on ik

The output equation had the form:


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Simulink Model

filter

i filter

To Workspace

VTSubsystem

i/cn hysteresis

Scope 5

Scope 4

Scope 3

Scope 2

Scope 1

Scope

Pulse

Generator 1

Pulse

Generator

Battery Cell

ik

i/cn

ocv

Add2

Add 1

Add


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Result

0 100 200 300 400 500 600 700 800 9001.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

Time (s)

Voltage

(V)

Experimental data

Model output


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Future Work

Pulse Discharging

SoH, SoF

Charging Algorithms

Optimum power usage

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Acknowledgement

Please use one of the following three languages

1. This work was supported by ERC Program ofthe National Science Foundation under AwardNumber EEC-08212121.

2. This work made use of ERC shared facilitiessupported by the National Science Foundationunder Award Number EEC-08212121.

3. This work was partially supported by theNational Science Foundation (NSF) underAward Number EEC-08212121.

Documents

Research Repot on A123 Battery Modeling