Ni-MH battery (LTspice simplified Model)

Ni-MH battery (LTspice simplified Model)

1. Nickel-Metal Hydride Battery
Simplified SPICE Behavioral Model
All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 1

2. Contents
1.Benefit of the Model
2.Model Feature
3.Concept of the Model
4.Parameter Settings
5.Ni-MhBattery Specification (Example)
5.1 Charge Time Characteristic
5.2 Discharge Time Characteristic
5.3 V
batvs. 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
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3. 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 reducetheconvergence error and the
simulation time.
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4. •This Ni-MH Battery Simplified SPICE Behavioral Modelis for users who
require the model of a Ni-MH Battery as a part of their system.
•The model accounts for Battery Voltage(V
bat) 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.
2. Model Feature
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Equivalent circuit of Li-Ion Battery model

5. 3. Concept of the Model
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Ni-Mhbattery
Simplified SPICE Behavioral Model
[Spec: C, NS]
Adjustable SOC [ 0-1(100%) ]
+
-
•The model is characterized by parameters: Cwhich represent the battery
capacity and SOCwhich represent the battery initial capacity level.
•Open-circuit voltage (V
OC) vs. SOC is included in the model as an analog
behavioral model (ABM).
•NS (Number of Cells in series) is used when the Ni-mhcells are in series to
increase battery voltage level.
Output
Characteristics

6. 4. Parameter Settings
•From the Ni-Mh Battery specification, the model is characterized by setting parameters
C, NS, SOC and TSCALE.
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Cis the amp-hour battery capacity [Ah]
–e.g. C = 0.3, 1.4, or 2.8 [Ah]
NSis 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)
SOCis the initial state of charge in percent
–e.g. SOC=0 for a empty battery (0%), SOC=1 for a full
charged battery (100%)
TSCALEturns 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.
Model Parameters:
(Default values)

7. 5. Ni-Mh Battery Specification (Example)
•The battery information refer to a battery part number HF-A1U of SANYO.
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Nominal Voltage 1.2V
Capacity
Typical 1350mAh
Minimum 1250mAh
Charging Current Time 1350mA about 1.1h
Discharge cut-off voltage 1.0V
Battery capacity
[Typ.] is input as a
model parameter

8. 5.1 Charge Time Characteristic
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•Charging Current: 1350mA about 1.1h
(min.)
Measurement Simulation
Charge: 1350mA
SOC=0 means
battery start from 0%
of capacity (empty)

9. 5.1 Charge Time Characteristic
Simulation Circuit and Setting
.TRAN 0 62 0 0.025
.LIB ni-mh_battery.sub
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Charge Voltage
A constant current charger at
rate of capacity (e.g. 11350mA)
1 minute into a second
(in simulation)

10. 5.2 Discharge Time Characteristic
.TRAN 0 360 0 100m
.STEP PARAM rate LIST 0.2, 1, 2
.LIB ni-mh_battery.sub
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0.2C
1C
2C
(min.)
•Battery voltage vs. time are simulated at 0.2C, 1.0C, and 2.0C discharge rates.
TSCALE turns 1 minute into a
second(in simulation), battery starts
from 100% of capacity (fully charged)

11. 0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 1 2 3 4 5
Actual Capacity
(% of Rated Capacity)
Discharge Rate (Multiples of C)
Mesurement
Simulation 5.3 V
batvs. SOC Characteristic
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•Nominal Voltage: 1.2V
•Capacity: 1350mAh
•Discharge cut-off voltage: 1.0V
2700mA
Measurement Simulation
Simulation
1350mA
270mA
(Ah)

12. 5.3 V
batvs. SOC Characteristic
Simulation Circuit and Setting
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.TRAN 0 360 0 100m
.STEP PARAM rate LIST 0.2, 1, 2
.LIB ni-mh_battery.sub
A constant current
discharger at rate of
capacity (e.g. 11350mA)
1 minute into a second
(in simulation)

13. 6. Extend the number of Cell (Example)
•The battery information refer to a battery part number HHR-150AAB01F7
of Panasonic.
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Voltage -Rated 8.4V
Capacity 1500mAh
Structure 1 Row x 7 Cells Side to Side
Number of Cells 7
Basic Specification2.1
4.8



VoltageNominal MH-Ni
RatedVoltage
NS
The number of cells
in series is input as
a model parameter
Ni-MH needs 7
cells to reach this
voltage level

14. 6.1 Charge Time Characteristic, NS=7
•Charging Current: 300mA (0.2 Charge)
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Voltage
(hour)
The battery needs 5 hours to be fully charged

15. 6.1 Charge Time Characteristic, NS=7
Simulation Circuit and Setting
.TRAN 0 5.2 0 2.5m
.LIB ni-mh_battery.sub
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1 hour into a second
(in simulation)
Charge Voltage

16. •Voltage -Rated: 8.4V
•Discharging Current: 300mA(0.2C), 750mA(0.5C), 1500mA(1.0C)
6.2 Discharge Time Characteristic, NS=7
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(hour)
0.2C
1C
0.5C

17. 6.2 Discharge Time Characteristic, NS=7
Simulation Circuit and Setting
.TRAN 0 6 0 2.5m
.STEP PARAM rate LIST 0.2, 0.5, 1
.OPTIONS RELTOL=0.01
.LIB ni-mh_battery.sub
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Parametric sweep “rate”
for multiple rate
discharge simulation
1 hour into a second
(in simulation)

18. Library Files and Symbol Files Location
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…\Simulation
C:\Program Files\LTC\LTspiceIV\lib\sub
C:\Program Files\LTC\LTspiceIV\lib\sym
Copy/
Paste
into
Copy/
Paste
into
1.Copy the library files (.lib) from the folder …\Simulation\.sub\, then paste into the folder C:\Program
Files\LTC\LTspiceIV\lib\sub
2.Copy the symbol files(.asy) from the folder …\Simulation\.asy\, then paste into the folder C:\Program
Files\LTC\LTspiceIV\lib\sym

19. Simulation Index
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Simulations Folder name
1.ChargeTimeCharacteristic.................................
2.DischargeTimeCharacteristic.............................
3.V
batvs. SOC Characteristic..................................
4.Charge Time Characteristic, NS=7.......................
5.Discharge Time Characteristic, NS=7...................
Charge_Time
Discharge_Time
Discharge_SOC
Charge_Time(NS)
Discharge_Time(NS)