Portable Rechargeable Output Power Portable Rechargeable Output Power SupplySupply

(PROPS)(PROPS)

Final PresentationFinal Presentation

April 24, 2008April 24, 2008

Team MembersTeam Members

Daniel Evans Daniel Evans Shane Morrison Shane Morrison

Drew Mills Drew Mills Josh GentryJosh Gentry

Outline:Outline:

IntroductionIntroductionProblem StatementProblem StatementSolutionSolutionConstraintsConstraintsOperationOperationTestingTestingConclusionConclusionReferencesReferences

ProblemProblem

Commercial Power Supplies:Commercial Power Supplies:– Not PortableNot Portable

Bench top and StationaryBench top and Stationary

Can only be used where AC is availableCan only be used where AC is available

Relatively large and heavyRelatively large and heavy

SolutionSolution

Portable Power SupplyPortable Power Supply– Lightweight and PortableLightweight and Portable– RechargeableRechargeable– Variable outputsVariable outputs– Large display to show voltage and current Large display to show voltage and current

outputoutput

Proposed LayoutProposed Layout

Top Level DiagramTop Level Diagram

+ Vout- Vout

-10 to 10 V350 mA

1 to 12 V3 A

Display

Linear Regulator

Linear Regulator

PIC

ADC

Buck Converter Charger Battery

Vin

120 VAC

Pots

Technical ConstraintsTechnical Constraints

Variable output from 1-12 voltsVariable output from 1-12 volts‒ 0.1 volt increments0.1 volt increments

Tracking output from -10 to 10 voltsTracking output from -10 to 10 volts

Current up to 3.5 ampsCurrent up to 3.5 amps

Output Ripple Voltage less than 5%Output Ripple Voltage less than 5%

Output error no greater than ± 50mVOutput error no greater than ± 50mV

Runtime of 1 hour at full capacityRuntime of 1 hour at full capacity

Practical Design ConstraintsPractical Design Constraints

EconomicEconomic– Manufactured for $120.00Manufactured for $120.00

Built in Power SupplyBuilt in Power Supply

Rechargeable BatteryRechargeable Battery

Display ScreenDisplay Screen

– Marketed for $250.00Marketed for $250.00

Practical Design ConstraintsPractical Design Constraints

Manufacturability Manufacturability – SizeSize

14” x 9” x 7”14” x 9” x 7”

– WeightWeight

< < 10 pounds10 pounds

– DurabilityDurability

Operation

Battery/Charger

Outputs

Voltage and Current Sensing

Operation (battery/charger)

Operation (battery/charger)

Battery Specs– 14.8 volts @ 4000 mA/h

Charger Specs– MAX1873

Input voltage up to 28 volts

Charge up to 4 cells

Charge up to 4 amps

Operation (battery/charger)

Battery Charging

Operation (battery/charger)

Operation (Output Circuits)

Operation of Circuits– DC/DC converters– Linear Regulators

Operation (1-12 volt output)

Operation (1-12 volt output)

Operation (Tracking output)

Operation (Tracking output)

Operation (Current Monitoring)

Hall-Effect Sensor ACS713– Monitors Current

Operation (Current Monitoring)

Operation (Software)

Video

Testing (battery/charger)

Vin (V) Vout 1 Iout 1 Vout 2 Iout 2 Time (min)

15.470 12.120 2.949 10.100 0.353 0.000

15.010 12.110 2.940 10.150 0.354 5.000

14.690 12.110 2.940 10.130 0.352 10.000

14.440 12.110 2.961 10.110 0.351 15.000

14.240 12.110 2.963 10.110 0.351 20.000

14.070 12.090 2.963 10.110 0.351 25.000

13.920 12.090 2.962 10.100 0.351 30.000

13.780 12.050 2.952 10.110 0.351 35.000

13.660 12.050 2.962 10.100 0.351 40.000

13.560 12.050 2.954 10.100 0.351 45.000

13.470 12.050 2.955 10.100 0.351 50.000

13.380 12.020 2.952 10.100 0.351 55.000

13.270 11.950 2.932 10.020 0.348 60.000

Battery Lifetime Test

Testing (battery/charger)Voltage Drop Over Time

11.900

11.950

12.000

12.050

12.100

12.150

0.000 10.000 20.000 30.000 40.000 50.000 60.000 70.000

Time (min)

Po

siti

ve O

utp

ut

(Vo

lts)

Current Drop Over Time

2.930

2.935

2.940

2.945

2.950

2.955

2.960

2.965

0.000 10.000 20.000 30.000 40.000 50.000 60.000 70.000

Time (min)

Cu

rren

t (a

mp

s)

Testing (1-12 volt output)

1 – 12 volt test data

Voltage (measured)

Voltage displayed on LCD % Error

Difference (V)

1.078 1.09 1.113 0.012

1.527 1.535 0.524 0.008

2.02 2.025 0.248 0.005

3.04 3.055 0.493 0.015

4.01 4.037 0.673 0.027

5 5.035 0.700 0.035

6.06 6.11 0.825 0.050

7.1 7.139 0.549 0.039

8.05 8.106 0.696 0.056

9.04 9.104 0.708 0.064

10.04 10.117 0.767 0.077

11.02 11.1 0.726 0.080

12.11 12.206 0.793 0.096

       

  Average: 0.623 0.026

Testing (Positive Tracking output)

Positive 1.5 – 10 volt

Voltage (measured)

Voltage displayed on LCD % Error

Difference (V)

1.001 0.996 0.500 0.005

1.525 1.509 1.049 0.016

2.05 2.039 0.537 0.011

3.03 3.019 0.363 0.011

4.01 4 0.249 0.010

5.03 4.996 0.676 0.034

6.02 5.992 0.465 0.028

7.1 7.066 0.479 0.034

8 7.969 0.388 0.031

9.15 9.105 0.492 0.045

10.06 10 0.596 0.060

11.04 10.97 0.634 0.070

12.01 11.95 0.500 0.060

       

  Average: 0.573 0.020

Testing (Negative Tracking Output)

Negative 1.5 – 10 volts

Voltage (measured) Voltage displayed on LCD % Error Difference (V)

0 0 0 0

-1.504 -1.4938 0.67819149 0.0102

-2.046 -2.0338 0.59628543 0.0122

-2.03 -2.0178 0.60098522 0.0122

-3 -3 0 0

-4.01 -4.0038 0.15461347 0.0062

-5.01 -5.0048 0.10379242 0.0052

-6.01 -6.0058 0.06988353 0.0042

-7 -6.99 0.14285714 0.01

-8.02 -8.006 0.17456359 0.014

-9 -8.9768 0.25777778 0.0232

-10.05 -10.024 0.25870647 0.026

-11.01 -10.993 0.15440509 0.017

-12.06 -12.02 0.33167496 0.04

       

  Average: 0.26067224 0.0101

Testing of Output CurrentTesting of Output CurrentApplied Current with Power

Supply (read with Fluke)Current displayed

on Display % Error0 0 0

0.103 0.084 18.450.202 0.201 0.4950.297 0.288 3.03

0.4 0.404 10.507 0.492 2.959

0.6 0.608 1.3330.702 0.695 0.9970.804 0.812 0.9950.899 0.899 01.01 1.016 0.594

1.098 1.103 0.4551.197 1.19 0.5851.304 1.307 0.231.399 1.394 0.3571.505 1.51 0.332

Testing Output Ripple

Testing (LCD)

LCD RS and R/W LCD Enable and DB7

Testing (Rotary Encoders)

Rotary Encoder Signals

Testing (Digital Pots)Testing (Digital Pots)

I2C lines to Digital Potentiometers

Results vs. Constraints

Constraint Pass Fail

1-12 Volt Output

Tracking Output

Output Current

Output Ripple

Output Error

Runtime

Future ImplementationsFuture Implementations

Rotary EncodersRotary Encoders

Digital PotentiometersDigital Potentiometers

DC/DC Converter DC/DC Converter

Future Implementations Future Implementations (Digital Pots)(Digital Pots)

Future Implementations Future Implementations (Rotary Encoders)(Rotary Encoders)

Design II Goals

Change prototype from a Linear Power Supply to a Switching Power Supply

Integrate new Digital Potentiometers into PROPS

Integrate Rotary Encoders

PCB layout

QuestionsQuestions