Device Modeling of Li-Ion battery MATLAB/Simulink Model

All Rights Reserved Copyright (C) Siam Bee Technologies 2015 1

Lithium-Ion Battery MATLAB/Simulink Model

Bee Technologies

http://www.bee-tech.info/

Device Modeling Service

Charge Characteristic

Discharge Characteristic

Device Modeling

Service MATLAB/Simulink Model




Contents

1. Model Feature 2. MATLAB/Simulink Model of Lithium-Ion Battery 3. Concept of the Model 4. Pin Configurations 5. Li-Ion Battery Specification (Example) 5.1 Charge Time Characteristic 5.1.1 Charge Time Characteristic (Simulation Circuit) 5.1.2 Charge Time Characteristic (Simulation Settings) 5.2 Discharge Time Characteristic (Simulation Circuit) 5.2.1 Discharge Time Waveform - 1400mAh (0.2C discharge) 5.2.2 Discharge Time Waveform - 1400mAh (0.5C discharge) 5.2.3 Discharge Time Waveform - 1400mAh (1.0C discharge) 5.2.4 Discharge Time Characteristic (Simulation Settings) 5.3 Vbat vs. SOC Characteristic 5.3.1 Vbat vs. SOC Characteristic (Simulation Circuit) 5.3.2 Vbat vs. SOC Characteristic (Simulation Settings) 6. Port Specifications

2 All Rights Reserved Copyright (C) Siam Bee Technologies 2015

• This Li-Ion Battery MATLAB/Simulink Model is for users who require the

model of a Li-Ion Battery as a part of their system.

• Battery Voltage(Vbat) vs. Battery Capacity Level (SOC) Characteristic, that can

perform battery charge and discharge time at various current rate conditions,

are accounted by the model.

• As a model, the effects of cycle number and temperature are neglected.

VSOC

2

MINUS

1

PLUS

VOC

+-

Rtransient_S

+-

Rtransient_L

+-

Rseries

Ibatt

+-

Ctransient_S

+-

Ctransient_L

+-

Capacity

1. Model Feature

3

Concept Circuit of Li-Ion Battery Circuit Model

All Rights Reserved Copyright (C) Siam Bee Technologies 2015

2. MTALAB/Simulink Model of Lithium-Ion Battery

4

Equivalent Circuit of Lithium-Ion Battery Model using MATLAB


1

VSOC

2

MINUS

1

PLUS

f(x)=0

Solver

Configuration

PSS

V+

-

PS S

+-

0.03

RTS

0.034

RTL

IBAT

RTS

CTS

CAH

N

TSCALE

RTCT_S

RTCT_S_EQV

IBAT

RTL

CTL

CAH

N

TSCALE

RTCT_L

RTCT_L_EQV

IBAT

RS

N

CAH

RSO

RS_EQV

0.045

RS

PS S

PSS

+

-

U

+

-

U

-K-

-K-

f(u)SOC VOUT

EOCV

I+

-

1800

CTS

15000

CTL

TSCALE

CAH

IBAT

SOC_SETTING

SOC0

CAPACITY

+-

4

%SOC

3

Tscale

2

C

1

NS

3. Concept of the Model

5

Li-Ion battery

MATLAB/Simulink Model

[Spec: C, NS]

Adjustable SOC : 0-100(%)

+

-

• The model is characterized by parameters: C, which represent the battery

capacity and SOC, which represent the battery initial capacity level.

• Open-circuit voltage (VOC) vs. SOC is included in the model as a behavioral

model.

• NS (Number of Cells in series) is used when the Li-ion cells are in series to

increase battery voltage level.

Output Characteristics


VBATT

Voch

(4.24*Ns)-0.07

VIN

5V1

Tscale

100

Soc

+-

V+

-

I+

-

SENSE_IBAT

PSS

PS S

OUTPUT

1

Ns

NS

C

Tscale

%SOC

VSOC

PLUS

MINUS

LI-ION_BATTERY

ICHG

0.5C (700mA)1.4

Capacity

4. Pin Configurations

C is the amp-hour battery capacity [Ah]

– e.g. C = 0.2, 1.4, or 2.0 [Ah]

NS is the number of cells in series

– e.g. NS=1 for 1 cell battery, NS=2 for 2 cells

battery (battery voltage is double from 1 cell)

SOC is the initial state of charge in percent

– e.g. SOC=0 for a empty battery (0%), SOC=100

for a full charged battery (100%)

TSCALE turns TSCALE seconds into a second

– e.g. TSCALE=60 turns 60s or 1min into a second

TSCALE=3600 turns 3600s or 1h into a second

• From the Li-Ion Battery specification, the model is characterized by setting parameters

C, NS, SOC and TSCALE.

6

Model Parameters:

Probe

“SOC”


VBATT

Voch

(4.24*Ns)-0.07

VIN

5V1

Tscale

100

Soc

+-

V+

-

I+

-

SENSE_IBAT

PSS

PS S

OUTPUT

1

Ns

NS

C

Tscale

%SOC

VSOC

PLUS

MINUS

LI-ION_BATTERY

ICHG

0.5C (700mA)1.4

Capacity

5. Li-Ion Battery Specification (Example)

• The battery information refer to a battery part number LIR18500 of EEMB BATTERY.

7

Battery capacity is input

as a model parameter Nominal Voltage 3.7V

Nominal

Capacity Typical 1400mAh (0.2C discharge)

Charging Voltage 4.20V±0.05V

Charging Std. Current 700mA

Max Current

Charge 1400mA

Discharge 2800mA

Discharge cut-off voltage 2.75V

Table 1


5.1 Charge Time Characteristic

8

• Charging Voltage: 4.20V±0.05V

• Charging Current: 700mA (0.5C Charge)

Current=700mA

Voltage=4.20V

Measuremet Data Simulation

SOC=0 means battery start

from 0% of capacity (empty)

%SOC

(Second)

VBATT

Voch

(4.24*Ns)-0.07

VIN

5V1

Tscale

0

Soc

+-V

+-

I+

-

SENSE_IBAT

PSS

PS S

OUTPUT

1

Ns

NS

C

Tscale

%SOC

VSOC

PLUS

MINUS

LI-ION_BATTERY

ICHG

0.5C (700mA)1.4

Capacity


VBATT

Voch

(4.24*Ns)-0.07

VIN

5V1

Tscale

0

Soc

+-

V+

-

I+

-

SENSE_IBAT

PSS

PS S

OUTPUT

1

Ns

NS

C

Tscale

%SOC

VSOC

PLUS

MINUS

LI-ION_BATTERY

ICHG

0.5C (700mA)1.4

Capacity

5.1.1 Charge Time Characteristic Simulation Circuit

9

Over-Voltage Protector:

(Charging Voltage*1) - VF of Diode

Input Voltage


5.1.2 Charge Time Characteristic Simulation Settings

10

Table 2: Simulation settings

Property Value

StartTime 0

StopTime 12000

AbsTol auto

InitialStep auto

ZcThreshold auto

MaxConsecutiveZCs 1000

NumberNewtonIterations 1

MaxStep 1

MinStep auto

MaxConsecutiveMinStep 1

RelTol 1e-3

SolverMode Auto

Solver ode23t

SolverName ode23t

SolverType Variable-step

SolverJacobianMethodControl auto

ShapePreserveControl DisableAll

ZeroCrossControl UseLocalSettings

ZeroCrossAlgorithm Adaptive

SolverResetMethod Fast


5.2 Discharge Time Characteristic Simulation Circuit

11

• Battery voltage vs. time are simulated at 0.2C, 0.5C, and 1C discharge rates.

battery starts from 100% of capacity

(fully charged)

VBAT

1

Tscale

100

Soc

V+

-

PSS

1

Ns

NS

C

Tscale

%SOC

VSOC

PLUS

MINUS

LI-ION_BATTERY

IDIS

0.2C (280mA)

1.4

Capacity


12

0.2C discharge (280mA)

5.2.1 Discharge Time Waveform 1400mAh (0.2C discharge)

• Nominal Voltage: 3.7V

• Discharge cut-off voltage: 2.75V

(Second)


13





(Second)


14





(Second)


15

5.2.4 Discharge Time Characteristic Simulation Settings


Property Value

StartTime 0

StopTime 24000, 9600, 4800

AbsTol auto

InitialStep auto

ZcThreshold auto



MaxStep 10

MinStep auto


RelTol 1e-3

SolverMode Auto

Solver ode23t

SolverName ode23t








0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 0.2 0.4 0.6 0.8 1

Dis

charg

e C

apacity

(%vs.

0.2

C)

Battery Discharge Current (vs. C Rate)

Mesurement

Simulation

5.3 Vbat vs. SOC Characteristic

16


• Capacity: 1400mAh (0.2C discharge)


2.60

2.80

3.00

3.20

3.40

3.60

3.80

4.00

4.20

4.40

-0.200.20.40.60.81

Vo

ltag

e (V

)

Capacity (%)

0.5C

0.2C

1C

Measurement Data Simulation

Simulation Vbat vs. SOC

1

Tscale

100

Soc V+

-

PSS

1

Ns

NS

C

Tscale

%SOC

VSOC

PLUS

MINUS

LI-ION_BATTERY

IDIS

1400mAh*(discharge rate)

1.4

Capacity

100

Cal

VBAT

SOC


5.3.1 Vbat vs. SOC Characteristic Simulation Circuit

17

Vbat vs. SOC

1

Tscale

100

Soc V+

-

PSS

1

Ns

NS

C

Tscale

%SOC

VSOC

PLUS

MINUS

LI-ION_BATTERY

IDIS

1400mAh*(discharge rate)

1.4

Capacity

100

Cal

VBAT

SOC


5.3.2 Vbat vs. SOC Characteristic Simulation Settings

18


Property Value

StartTime 0

StopTime 19200

AbsTol auto

InitialStep auto

ZcThreshold auto



MaxStep 10

MinStep auto


RelTol 1e-3

SolverMode Auto

Solver ode23t

SolverName ode23t








6. Port Specifications

19

Table 6

Parameter Simulink Simscape

NS O

C O

TSCALE O

%SOC O

VSOC O

PLUS O

MINUS O

Voch

(4.2*Ns)-6.5m

VSOC

VIN

5V

VBAT60

Tscale

0

Soc

+-V

+-

SENSE_VBAT

I+

-

SENSE_IBAT

PS S

PS S

1

Ns

NS

C

Tscale

%SOC

VSOC

PLUS

MINUS

LI-ION_BATTERY

ICHG

0.5C

IBAT

1.4

Capacity

Battery Model


Date post:	23-Jul-2015
Category:	Engineering
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Device Modeling of Li-Ion battery MATLAB/Simulink Model

Engineering