Simple Model of Ni-MH Battery Model using PSpice

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

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.


• 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


3. Concept of the Model


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

-+

U 1

N I -M H _ B A TTE R Y

C = 1 3 5 0 MTS C A L E = 1

N S = 1S O C = 1

4. Parameter Settings

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.

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


Model Parameters:

(Default values)

-+

U 1


C = 1 3 5 0 M

TS C A L E = 1

N S = 1

S O C = 1

5. Ni-Mh Battery Specification (Example)

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


Battery capacity [Typ.] is input as a model parameter

Battery capacity [Typ.] is input as a model parameter

Nominal Voltage 1.2V

Capacity

Typical 1350mAh

Minimum 1250mAh

Charging Current Time 1350mA about 1.1h

Discharge cut-off voltage 1.0V

Time

0s 10s 20s 30s 40s 50s 60s 70s 80sV(HI)

1.0V

1.1V

1.2V

1.3V

1.4V

1.5V

1.6V

1.7V

1.8V

5.1 Charge Time Characteristic


• Charging Current: 1350mA about 1.1h

(min.)

Measurement Simulation

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

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

-+

U 1


C = 1 3 5 0 MTS C A L E = 6 0

N S = 1S O C = 0

Charge: 1350mA

PARAMETERS:ra t e = 1C A h = 1 3 5 0 m

0

V in3 V

I B A TT0

C 11 0 n

H I

IN-

OUT+

OUT-

IN+

G 1L im it (V (% I N +, % I N -)/ 1 m , 0 , ra t e * C A h ) 0

-+

U 1


C = 1 3 5 0 MTS C A L E = 6 0

N S = 1S O C = 0

5.1 Charge Time Characteristic Simulation Circuit and Setting

*Analysis directives: .TRAN 0 62 0 25m .PROBE V(*) I(*) W(*) D(*) NOISE(*)


1 minute into a second (in simulation)


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)

Time

0s 60s 120s 180s 240s 300s 360sV(HI)

0.9V

1.0V

1.1V

1.2V

1.3V

1.4V

1.5V

1.6V

H I

0

0

0IN-

OUT+

OUT-

IN+

G 1

lim it (V (% I N + , % I N -)/ 1 m , 0 , ra t e * C A h )G V A L U E


C 11 0 n

s e n s e

-+

U 1


C = 1 3 5 0 MTS C A L E = 6 0

N S = 1S O C = 1

5.2 Discharge Time Characteristic

*Analysis directives: .TRAN 0 360 0 100m .STEP PARAM rate LIST 0.2,1,2 .PROBE V(*) I(*) W(*) D(*) NOISE(*)


0.2C

1C

2C

(min.)

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)

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

-+

U 1


C = 1 3 5 0 MTS C A L E = 6 0

N S = 1S O C = 1

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

0 250 500 750 1000 1250 1500

Cel

l Vo

ltag

e [V

]

Discharge Capacity [mAh]

0.2C (270mA)1.0C (1350mA)2.0C (2700mA)

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


• Nominal Voltage: 1.2V• Capacity: 1350mAh• Discharge cut-off voltage: 1.0V

2700mA

Measurement Simulation

Simulation

1350mA270mA

H I

0

0

0IN-

OUT+

OUT-

IN+

G 1


PARAMETERS:ra t e = 0 . 2C A h = 1 3 5 0 m

C 11 0 n

s e n s e

-+

U 1


C = 1 3 5 0 MTS C A L E = 6 0

N S = 1S O C = 1

5.3 Vbat vs. SOC Characteristic Simulation Circuit and Setting


*Analysis directives: .TRAN 0 296.4 0 100m .PROBE V(*) I(*) W(*) D(*) NOISE(*)

A constant current discharger at rate of

capacity (e.g. 11350mA)

A constant current discharger at rate of

capacity (e.g. 11350mA)



-+

U 1


C = 1 5 0 0 M

TS C A L E = 3 6 0 0

N S = 7

S O C = 1

6. Extend the number of Cell (Example)

• The battery information refer to a battery part number HHR-150AAB01F7

of Panasonic.


The number of cells in series is input as a model parameter

The number of cells in series is input as a model parameter

Voltage - Rated 8.4V

Capacity 1500mAh

Structure 1 Row x 7 Cells Side to Side

Number of Cells 7

Basic Specification

Ni-MH needs 7 cells to reach

this voltage level

Ni-MH needs 7 cells to reach

this voltage level

2.1

4.8

VoltageNominal MH-NiRatedVoltage

NS

Time

0s 1s 2s 3s 4s 5s 6s 7s 8s 9s 10sV(HI)

7.0V

7.7V

8.4V

9.1V

9.8V

10.5V

11.2V

11.9V

12.6V

6.1 Charge Time Characteristic, NS=7

• Charging Current: 300mA (0.2 Charge)


Voltage

(hour)

The battery needs 5 hours to be fully charged

PARAMETERS:ra t e = 0 . 2C A h = 1 5 0 0 m

0

V in1 2 V

I B A TT0

C 11 0 n

H I

0

IN-

OUT+

OUT-

IN+

G 1L im it (V (% I N +, % I N -)/ 1 m , 0 , ra t e * C A h )

-+

U 1


C = 1 5 0 0 MTS C A L E = 3 6 0 0

N S = 7S O C = 0

6.1 Charge Time Characteristic, NS=7 Simulation Circuit and Setting

*Analysis directives: .TRAN 0 5.2 0 2.5m .PROBE V(*) I(*) W(*) D(*) NOISE(*)


Charge VoltageCharge Voltage

1 hour into a second (in simulation)


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

Time

0s 1.0s 2.0s 3.0s 4.0s 5.0s 6.0sV(HI)

6.3V

7.0V

7.7V

8.4V

9.1V

9.8V

10.5V

11.2V

6.2 Discharge Time Characteristic, NS=7


(hour)

0.2C

1C

0.5C

H I

0

0

0IN-

OUT+

OUT-

IN+

G 1



C 11 0 n

s e n s e

-+

U 1


C = 1 5 0 0 MTS C A L E = 3 6 0 0

N S = 7S O C = 1

6.2 Discharge Time Characteristic, NS=7 Simulation Circuit and Setting

*Analysis directives: .TRAN 0 6 0 2.5m .STEP PARAM rate LIST 0.2,0.5,1 .PROBE V(*) I(*) W(*) D(*) NOISE(*)


Parametric sweep “rate” for multiple rate discharge simulation

Parametric sweep “rate” for multiple rate discharge simulation



Simulation Index


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)

Simple Model of Ni-MH Battery Model using PSpice

Technology

parameters c

cells battery ts c

h ts c

battery charge

model nimh battery

c secondin simulation

c discharge rates

cell battery