SOLAR PANEL CHARGE

CONTROLLER FOR INDOOR ROBOT

Ngo Khac Hoang

University of Engineering and Technology

Vietnam National University, Hanoi

Supervisor – Dr. Aaron James Danner

Internship Final Presentation

Contents

Overview of project

Power charging circuit

Future work

Internship Final Presentation

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2

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• Objective – Build a power charging circuit for a lightweight INDOOR ROBOT

• Required input voltage of robot: 1.8 – 3.6 V

• 24 amorphous silicon solar cells being used

Overview

Robot from Wall – E movie Mobile Detection and Response System

(MDARS)

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0 1 2 3 4 5 6 70

100

200

300

400

500

600

Po

we

r (µ

W)

Voltage (V)

256 lux

315 lux

417 lux

561 lux

631 lux

720 lux

Intensity value 256 – 720 lux

Maximum Power Point 190.464 – 600.237 μW

Overview

With stable light intensity• Non-linear relationship between current and voltage

• 1 Maximum Power Point (MPP)

Solar cell parameters change when the intensity of light changes

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Charge controller

Overview

Non-linear

I-V

characteristic

Track the

MPP

Current and

Voltage

Unstable

Maintain

parameters

(voltage)

Charge

Controller

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Make useful

combinations for

charging circuit

Use a micro-

controller circuit

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Internship Final Presentation

Power Charging Circuit

Arranging solar cells in a useful combination to get the target output voltage

Required conditions – maintain target voltage and maximum power

Solution – Symmetrical combination of solar cells

n = solar panels

MPP of each: (V, I)

𝑴𝒂𝒙𝒊𝒎𝒖𝒎𝑷𝒐𝒘𝒆𝒓 = 𝒂𝑽 ∗ 𝒃𝑰 = 𝐚𝐛𝐕𝐈 = 𝐧𝐕𝐈𝒂𝑽 = 𝑽𝒐𝒍𝒕𝒂𝒈𝒆 𝒐𝒇 𝒘𝒉𝒐𝒍𝒆 𝒔𝒚𝒔𝒕𝒆𝒎

𝒃𝑰 = 𝑪𝒖𝒓𝒓𝒆𝒏𝒕 𝒐𝒇 𝒘𝒉𝒐𝒍𝒆 𝒔𝒚𝒔𝒕𝒆𝒎

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Simplify: Divide 24 panels into (6 blocks * 4 panels)

n = 24

Power Charging Circuit

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a columns

b rows

No. CombinationSwitches

Closed

1. a = 1, b = 4 1,2,7,5,6,9

2. a = 2, b = 2 1,2,3,4,6

3. a = 4, b = 1 3, 8,4

Power Charging Circuit

𝑴𝒂𝒙𝒊𝒎𝒖𝒎𝑷𝒐𝒘𝒆𝒓 = 𝒂𝑽 ∗ 𝒃𝑰 = 𝐚𝐛𝐕𝐈 = 𝐧𝐕𝐈

3 USEFUL

SYMMETRICAL COMBINATIONS

Internship Final Presentation

1 Block = 4 solar cells

𝒏 = 𝟒 = 1 ∗ 4 = 2 ∗ 2 = 4 ∗ 1

Switch = MOSFET

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No. CombinationSwitches

Closed

1. a = 1, b = 61,2,5,6,9,10,11,

12,13,14

2. a = 2, b = 31,2,3,4,6,7,8,1

0

3. a = 3, b = 2 1,3,4,7,8,10

4. a = 6, b = 1 3,4,7,8,15

6 Blocks = 24 solar cells 𝒏 = 𝟔 = 6 ∗ 1 = 2 ∗ 3 = 3 ∗ 2 = 6 ∗ 1

4 USEFUL

SYMMETRICAL COMBINATIONS

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No.Combination of 24

panels

Combination of 6

blocks

Combination in each

block

1. (1,24) (1,6) (1,4)

2. (2,12) (2,3) (1,4)

3. (3,8) (3,2) (1,4)

4. (4,6) (1,6) (4,1)

5. (6,4) (6,1) (1,4)

6. (8,3) (2,3) (4,1)

7. (12,2) (6,1) (2,2)

8. (24,1) (6,1) (4,1)

(m*x , p*y) (m , p) (x , y)

Combination of 24 solar panels (6 Blocks)

𝒏 = 𝟐𝟒 = 1 ∗ 24 = 2 ∗ 12 = 3 ∗ 8 = 4 ∗ 6 = 6 ∗ 4 = 8 ∗ 3 = 12 ∗ 2 = 24 ∗ 1

8 USEFUL SYMMETRICAL COMBINATIONS

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Combination of 24 solar panels (6 Blocks) with microcontroller

Microcontroller

Bit combinations

000 100

001 101

010 110

011 111

SYSTEM24 solar panels

+

microcontroller

Vmeas

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A microcontroller uses 3 bits to select one of the 8 combinations.

The bits are then used to open and close the appropriate MOSFET switches.

Construction of real charging circuit

Program a low power microcontroller

Conduct test experiments to find the best symmetrical

combination

Future Work

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Acknowledgements

Department of Electrical and Computer Engineering,

National University of Singapore for giving me this

internship opportunity.

Dr. Aaron James Danner for guiding me in this project.

Internship Final Presentation

Internship Final Presentation

Thank You

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