Simple Model of Ni-MH Battery Model using LTspice

Nickel-Metal Hydride Battery
Simplified SPICE Behavioral Model

All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 1

Contents
1. Benefit of the Model
2. Model Feature
3. Concept of the Model
4. Parameter Settings
5. Ni-Mh Battery Specification (Example)
5.1 Charge Time Characteristic
5.2 Discharge Time Characteristic
5.3 Vbat vs. SOC Characteristic
6. Extend the number of Cell (Example)
6.1 Charge Time Characteristic, NS=7
6.2 Discharge Time Characteristic, NS=7
Library Files and Symbol Files Location
Simulation Index


1. Benefit of the Model

• The model enables circuit designer to predict and optimize Ni-MH
battery runtime and circuit performance.

• The model can be easily adjusted to your own Ni-MH 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.


2. Model Feature

• This Ni-MH Battery Simplified SPICE Behavioral Model is for users who
require the model of a Ni-MH Battery as a part of their system.
• The model accounts for Battery Voltage(Vbat) vs. Battery Capacity Level (SOC)
Characteristic, so it can perform battery charge and discharge time at
various current rate conditions.
• As a simplified model, the effects of cycle number and temperature are
neglected.


3. Concept of the Model

Ni-Mh battery +
Simplified SPICE Behavioral Model
[Spec: C, NS]
Output
Characteristics
Adjustable SOC [ 0-1(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 an analog
behavioral model (ABM).
• NS (Number of Cells in series) is used when the Ni-mh cells are in series to
increase battery voltage level.


4. Parameter Settings
Model Parameters:
C is the amp-hour battery capacity [Ah]
– e.g. C = 0.3, 1.4, or 2.8 [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=1 for a full
charged battery (100%)

(Default values) TSCALE turns TSCALE seconds(in the real world) into a
second(in simulation)
– e.g. TSCALE=60 turns 60s or 1min (in the real world)
into a second(in simulation), TSCALE=3600 turns 3600s
or 1h into a second.

• From the Ni-Mh Battery specification, the model is characterized by setting parameters
C, NS, SOC and TSCALE.


5. Ni-Mh Battery Specification (Example)

Nominal Voltage 1.2V

Typical 1350mAh
Capacity
Minimum 1250mAh

Charging Current × Time 1350mA × about 1.1h

Discharge cut-off voltage 1.0V
Battery capacity
Battery capacity
[Typ.] is input as aa
[Typ.] is input as
model parameter
model parameter

• The battery information refer to a battery part number HF-A1U of SANYO.


Measurement Simulation

Charge: 1350mA

(min.)

• Charging Current: 1350mA × about 1.1h

SOC=0 means
SOC=0 means
battery start from 0%
battery start from 0%
of capacity (empty)
of capacity (empty)


− Simulation Circuit and Setting

Charge Voltage
Charge Voltage

AAconstant current charger at
constant current charger at
rate of capacity (e.g.
rate of capacity (e.g.
1×1350mA)
1×1350mA)
11minute into aa
minute into
second (in simulation)

.TRAN 0 62 0 0.025
.LIB ni-mh_battery.sub


5.2 Discharge Time Characteristic
• Battery voltage vs. time are simulated at 0.2C, 1.0C, and 2.0C discharge rates.

0.2C

TSCALE turns 11minute into aa
TSCALE turns minute into
second(in simulation), battery starts
second(in simulation), battery starts 1C
from 100% of capacity (fully
from 100% of capacity (fully
charged)
charged) 2C

.TRAN 0 360 0 100m (min.)
.STEP PARAM rate LIST 0.2, 1, 2


Measurement Simulation

270mA
1350mA
2700mA

(Ah)

Simulation
1.2
1.0

0.8

0.6

0.4
Mesurement
0.2
C
A

• Nominal Voltage: 1.2V
p
a
u
y
c

Simulation
t
i
l
%
C
R

0.0
p
d
e
a
o
y
c
)
(
t
f
i

• Capacity: 1350mAh 0 1 2 3 4 5
• Discharge cut-off voltage: 1.0V Discharge Rate (Multiples of C)



AAconstant current
constant current
discharger at rate of
discharger at rate of
capacity (e.g. 1×1350mA)
capacity (e.g. 1×1350mA)
11minute into aa
minute into

.TRAN 0 360 0 100m
.STEP PARAM rate LIST 0.2, 1, 2


6. Extend the number of Cell (Example)

Ni-MH needs 77
Ni-MH needs
cells to reach
cells to reach
this voltage level
this voltage level
Basic Specification

Voltage - Rated 8.4V

Capacity 1500mAh

Structure 1 Row x 7 Cells Side to Side
The number of
The number of
cells in series is
cells in series is Number of Cells 7
input as aamodel
input as model
parameter
parameter

Voltage − Rated 8.4
NS = =
Ni - MH Nominal Voltage 1.2
• The battery information refer to a battery part number HHR-150AAB01F7
of Panasonic.


The battery needs 5 hours to be fully charged

Voltage

(hour)

• Charging Current: 300mA (0.2 Charge)



Charge Voltage
Charge Voltage

11hour into aasecond
hour into second
(in simulation)
(in simulation)
.TRAN 0 5.2 0 2.5m



0.2C

0.5C

1C

(hour)

• Voltage - Rated: 8.4V
• Discharging Current: 300mA(0.2C), 750mA(0.5C), 1500mA(1.0C)


Parametric sweep
Parametric sweep
“rate” for multiple rate
“rate” for multiple rate
discharge simulation
discharge simulation

11hour into aasecond
hour into second
(in simulation)
(in simulation)

.TRAN 0 6 0 2.5m
.STEP PARAM rate LIST 0.2, 0.5, 1
.OPTIONS RELTOL=0.01

Library Files and Symbol Files Location
…Simulation

Copy/
Copy/
Paste
Paste C:Program FilesLTCLTspiceIVlibsub
into
into

Copy/
Copy/
Paste
Paste
into
into C:Program FilesLTCLTspiceIVlibsym

1. Copy the library files (.lib) from the folder …Simulation.sub, then paste into the folder C:Program
FilesLTCLTspiceIVlibsub
2. Copy the symbol files(.asy) from the folder …Simulation.asy, then paste into the folder
C:Program FilesLTCLTspiceIVlibsym


Simulation Index

Simulations Folder name
1. Charge Time Characteristic................................. Charge_Time
2. Discharge Time Characteristic............................. Discharge_Time
3. Vbat vs. SOC Characteristic.................................. Discharge_SOC
4. Charge Time Characteristic, NS=7....................... Charge_Time(NS)
5. Discharge Time Characteristic, NS=7................... Discharge_Time(NS)


Simple Model of Ni-MH Battery Model using LTspice

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (19)

Similar to Simple Model of Ni-MH Battery Model using LTspice

Similar to Simple Model of Ni-MH Battery Model using LTspice (20)

More from spicepark

More from spicepark (20)

Recently uploaded

Recently uploaded (20)

Simple Model of Ni-MH Battery Model using LTspice