simple model of ni-mh battery model using ltspice
DESCRIPTION
Simple Model of Ni-MH Battery Model using LTspice by Bee TechnologiesTRANSCRIPT
Nickel-Metal Hydride BatterySimplified 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
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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.
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• 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.
2. Model Feature
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3. Concept of the Model
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Ni-Mh batterySimplified SPICE Behavioral Model
[Spec: C, NS]
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.
Output Characteristics
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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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%)
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.
Model Parameters:
(Default values)
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 1.0VBattery capacity
[Typ.] is input as a model parameter
Battery capacity [Typ.] is input as a model parameter
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)
SOC=0 means battery start from 0% of capacity (empty)
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 VoltageCharge Voltage
A constant current charger at rate of capacity (e.g.
11350mA)
A constant current charger at rate of capacity (e.g.
11350mA) 1 minute into a
second (in simulation)1 minute into a
second (in simulation)
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)
TSCALE turns 1 minute into a second(in simulation), battery starts
from 100% of capacity (fully charged)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 1 2 3 4 5
Act
ual C
apac
ity(%
of R
ated
Cap
acity
)
Discharge Rate (Multiples of C)
Mesurement
Simulation
5.3 Vbat vs. SOC Characteristic
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• Nominal Voltage: 1.2V• Capacity: 1350mAh• Discharge cut-off voltage: 1.0V
2700mA
Measurement Simulation
Simulation
1350mA270mA
(Ah)
5.3 Vbat vs. 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. 11350mA)
A constant current discharger at rate of
capacity (e.g. 11350mA)
1 minute into a second (in simulation)
1 minute into a second (in simulation)
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 Specification
2.1
4.8
VoltageNominal MH-NiRatedVoltage
NS
The number of cells in series is input as a model parameter
The number of cells in series is input as a model parameter
Ni-MH needs 7 cells to reach
this voltage level
Ni-MH needs 7 cells to reach
this voltage level
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
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)
1 hour into a second (in simulation)
Charge VoltageCharge Voltage
• 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
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
Parametric sweep “rate” for multiple rate discharge simulation
1 hour into a second (in simulation)
1 hour into a second (in simulation)
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
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
Simulation Index
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Simulations Folder name
1. Charge Time Characteristic.................................
2. Discharge Time Characteristic.............................
3. Vbat vs. 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)