Lithium Ion Battery Simplified Simulink Model using MATLAB

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

MATLAB Version

Lithium Ion Battery Simplified Simulink Model

using MATLAB

Bee Technologies

Contents

1. Benefit of the Model 2. Model Feature 3. Simulink Model of Lithium-Ion Battery 4. Concept of the Model 5. Pin Configurations 6. Li-Ion Battery Specification (Example) 6.1 Charge Time Characteristic 6.1.1 Charge Time Characteristic (Simulation Circuit) 6.1.2 Charge Time Characteristic (Simulation Settings) 6.2 Discharge Time Characteristic (Simulation Circuit) 6.2.1 Discharge Time Waveform - 1400mAh (0.2C discharge) 6.2.2 Discharge Time Waveform - 1400mAh (0.5C discharge) 6.2.3 Discharge Time Waveform - 1400mAh (1.0C discharge) 6.2.4 Discharge Time Characteristic (Simulation Settings) 6.3 Vbat vs. SOC Characteristic 6.3.1 Vbat vs. SOC Characteristic (Simulation Circuit) 6.3.2 Vbat vs. SOC Characteristic (Simulation Settings) 7. Extend the number of Cell (Example) 7.1.1 Charge Time Circuit - NS=4, TSCALE=3600 7.1.2 Charge Time Waveform - NS=4, TSCALE=3600 7.2.1 Discharge Time Circuit - NS=4, TSCALE=3600 7.2.2 Discharge Time Waveform - NS=4, TSCALE=3600 7.3 Charge & Discharge Time (Simulation Settings)

8. Port Specifications

Simulation Index

Appendix Diode

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

1. Benefit of the Model

• The model enables circuit designer to predict and optimize battery

runtime and circuit performance.

• The model can be easily adjusted to your own battery specifications

by editing a few parameters that are provided in the datasheet.

• The model is optimized to reduce the convergence error and the

simulation time


• This Li-Ion Battery Simplified 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 simplified model, the effects of cycle number and temperature are

neglected.

2. Model Feature

4

Battery Circuit Model

All Rights Reserved Copyright (C) Siam Bee Technologies 2015

3. Simulink Model of Lithium-Ion Battery

5

Equivalent Circuit of Lithium-Ion Battery Model using Matlab


2

MINUS

1

PLUS

4. Concept of the Model

6

Li-Ion battery

Simplified 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

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

5. 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.

7

Model Parameters:

All Rights Reserved Copyright (C) Bee Technologies Corporation 2015

Probe

“SOC”


6. Li-Ion Battery Specification (Example)

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

8

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


6.1 Charge Time Characteristic

9

• Charging Voltage: 4.20V±0.05V

• Charging Current: 700mA (0.5C Charge)

Current=700mA

Voltage=4.20V

Datasheet Simulation

SOC=0 means battery start

from 0% of capacity (empty)


%SOC

(Second)


6.1.1 Charge Time Characteristic Simulation Circuit

10

Over-Voltage Protector:

(Charging Voltage*1) - VF of Diode

Input Voltage


6.1.2 Charge Time Characteristic Simulation Settings

11 All Rights Reserved Copyright (C) Bee Technologies Corporation 2015

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


6.2 Discharge Time Characteristic Simulation Circuit


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

battery starts from 100% of capacity

(fully charged)


13

0.2C discharge (280mA)


6.2.1 Discharge Time Waveform 1400mAh (0.2C discharge)

• Nominal Voltage: 3.7V

• Discharge cut-off voltage: 2.75V

(Second)


14






(Second)


15






(Second)



6.2.4 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

6.3 Vbat vs. SOC Characteristic

17


• 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

Datasheet Simulation

Simulation


6.3.1 Vbat vs. SOC Characteristic Simulation Circuit

18 All Rights Reserved Copyright (C) Bee Technologies Corporation 2015 All Rights Reserved Copyright (C) Siam Bee Technologies 2015

6.3.2 Vbat vs. SOC Characteristic Simulation Settings



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








• The battery information refer to a battery part number PBT-BAT-0001 of BAYSUN

Co., Ltd.

20

The number of cells in

series is input as a model

parameter

Output Voltage DC 12.8~16.4V

Capacity of Approximately 4400mAh

Input Voltage DC 20.5V

Charging Time About 5 hours

Basic Specification

Li-ion needs 4 cells to

reach this voltage level


7. Extend the number of Cell (Example) NS=4, TSCALE=3600

1 hour into a second

(in simulation)


7.1.1 Charge Time Circuit NS=4, TSCALE=3600

21

Input Voltage

Over-Voltage Protector:

(Charging Voltage 4) - VF of Diode


Number of Cells


22

• Input Voltage: 20.5V

• Charging Voltage: 16.8V

• Charging Current: 880mA (0.2 Charge)

Current=880mA

Voltage=16.8V

Capacity=100%

(hour)

The battery needs 5 hours to be fully charged


7.1.2 Charge Time Waveform NS=4, TSCALE=3600

BATTERY PACK LI-ION 12.8~16.4V

Number of Cells: 4


7.2.1 Discharge Time Circuit NS=4, TSCALE=3600


Number of Cells

• Output Voltage: 12.8~16.4V

• Capacity: 4400mAh

• Discharge Current: 2200mA (0.5C)


24

2200mA (0.5C)

16.4V

12.8V

Output

voltage

range


7.2.2 Discharge Time Waveform NS=4, TSCALE=3600

• Output Voltage: 12.8~16.4V

• Capacity: 4400mAh

• Discharge Current: 2200mA (0.5C)

BATTERY PACK LI-ION 12.8~16.4V

Number of Cells: 4

(hour)


7.3 Charge & Discharge Time Simulation Settings



Property Value

StartTime 0

StopTime 8, 3

AbsTol auto

InitialStep auto

ZcThreshold auto



MaxStep 0.01

MinStep auto


RelTol 1e-3

SolverMode Auto

Solver ode23t

SolverName ode23t








8. Port Specifications


Table 6

Parameter Simulink Simscape

NS O

C O

TSCALE O

%SOC O

VSOC O

PLUS O

MINUS O

Battery Model


Simulation Index

27

Simulations Folder name

1. Charge Time Characteristic..................................................

2. Discharge Time Characteristic..............................................

3. Vbat vs. SOC Characteristic...................................................

4. Charge Time Characteristic - NS=4, TSCALE=3600.............

5. Discharge Time Characteristic - NS=4, TSCALE=3600.........

Charge_Time

Discharge_Time

Discharge_SOC

Charge_Time(NS)

Discharge_Time(NS)


Appendix


If Diode is error, Please choice Diode of SPICE-Compatiable

Semiconductors/Diode

Appendix


Setting of Diode

Emission coefficient ,ND Default Value change 0.01

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Lithium Ion Battery Simplified Simulink Model using MATLAB