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EBaM:an EDA tool for Battery Modeling

POLITO

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Outline…Energy efficiency is often centered around the “device”…But overall efficiency can be decided in other parts of the “energy

path”

DC-DCconverter/

charger

MPPT &

control

load

Energy source

I, V

t

DC-DCconverter

Energy storage device (ESD)(Optional)

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Limitations: Costs & Time: calculation of model parameters is

based on actual measurements Lack of generality: a given circuit/model cannot be

used to represent another device, i.e., validation is carried out on the specific battery under measure

Solution: Modeling from datasheet: resort to information

available in the datasheets provided by the battery manufacturers;

Variable accuracy model templates: since datasheets often provide limited info, adapt the model template (accuracy) to the amount of information.

Automation for battery modelingMany battery models, with different complexities, are proposed in literature.

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EBaM Framework

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Battery Models should include...

I-order effects:

Battery runtime;

SOC-OCV relation;

SOC-transient response relation.

II-order effects:

Temperature effects on battery

voltage;

Temperature effects on capacity;

Capacity fading due to cycling and

storage (aging).

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Model levels overview  Level 1 Level 2 Level 3

I Orde

r Effec

ts

RunTime SOC

RunTime SOC Steady-State

Response

RunTime SOC Steady-State

Response Transient

Response

II Orde

r Effec

ts

Level 1+ Temperature

Level 2+ Temperature

Level 3+ Temperature

Level 1+ Capacity Fading

Level 2+ Capacity Fading

Level 3+ Capacity Fading

HIGHER ACCURACY

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Level 1 model

Current (A)

Time (h)

Temperature (°C)(d)

(I,T,LT) FROM DATASHEET

PEUKERT’S FITTING SURFACE

TIME (h)(a)

VOLTAGE (V

)

VOLTAGE (V

)

VOLTAGE (V

)

(b) (c)

@ Tref

Vcutoff

TIME (h) TIME (h)

@ T1 @ T2

Vcutoff Vcutoff

TEMPERATURE EFFECTS

I1LT1

(I1,Tref,LT1)

battery runtime; temperature effects; possibility to further extend

it for capacity fade.

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Level 2 modelEquivalent electric circuit model

battery runtime; SOC-OCV relation; temperature effects; possibility to extend it

for capacity fade.

+-

C M(T)

VSOC

I B

+ +R(VSOC)VB

VR -+-IB

(d)

c1TEMPERATURE(T)(a)

CAPACITY(A

h)

DISCHARGE CAPACITY (Ah)

VOLTAGE (V

)

DISCHARGE CAPACITY (Ah)VOLTA

GE (V)

c2 cref

(b) (c)TrefT1T2T3

+-

TEMPERATURE EFFECTS

@ cref @ Tref@ cref

VOC(VSOC)VDRIFT(T,VSOC)

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Level 3 model

battery runtime; SOC-OCV relation

(transient); temperature effects; possibility to extend it

for capacity fade.+-V OC(V

SOC)C M

VSOC

I B

+ +R(VSOC) RS(VSOC)CS(VSOC)

RL(VSOC)CL(VSOC)

(a)

CURRENT (A

)/VOLTAGE

(V)

TIME (s)VOLTA

GE (V)

TIME (s)τS τL

VRVS VL

VB

(b)

VR -+VS -+ VL -+

VOLTAGE DROP: OHIMC LOSSES BETWEEN ELECTRODES AND ELECTROLYTELONG-TIME EFFECT: DIFFUTION PHENOMENA IN THE ELECTROLYTE

SHORT-TIME EFFECT:DOUBLE LAYER CAPACITY tS tL s

-IB(c)

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AccuracyLevel 2

Level 3

Sony UP383562

Energizer CR2032constant current @0.0008C 2s @0.1C