EE1111A PROJECT��Design and Prototyping of a Smart Solar-Powered Street Lamp �

by Team 3 B06

Jung Jihoon, Justin Yeo Wei Jie, Kim Hogyun, Manya Gupta, You Qixuan, Zhu Yuxin

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Table of contents

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System Design

Introduction

Detailed Calculations

• User requirements
• Technical requirements

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• Brief background
• Project objectives

• Risk / Opportunities
• Functional block diagram

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• LED
• Battery sizing
• PV panel

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Project Specifications

Testing & Challenges

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Prototype & BOM

Conclusion

• Flowchart & Code
• Arduino brightness control

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• 3D model, 2D schematic
• Bill of Materials (BOM)

• Testing Results
• Challenges & Solutions

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• Summary
• Limitations & Future improvements

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Control Logic

Introduction

• Designing Sustainable Lighting for Rural Communities

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Our project focuses on creating an affordable, smart solar-powered street lamp tailored for rural and off-grid communities, especially in areas near Singapore. With limited access to electricity, these areas require sustainable and autonomous lighting solutions that can improve safety and quality of life without relying on the traditional power grid.

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By harnessing solar energy and incorporating adaptive brightness control, this project aims to provide a reliable, environmentally friendly lighting system that can operate independently. The design meets essential requirements for rural deployment, including minimal maintenance, high efficiency, and cost-effectiveness.

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Project Specifications

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User Requirements

• Solar-powered operation: The lamp should store energy from a PV panel during the day and utilize it at night.
• Battery reliability: Batteries should last for at least two nights when fully charged to account for rainy or overcast days.
• Automatic control: The lamp should turn on automatically at dusk and turn off at dawn.
• Illumination standard: The lamp must provide a minimum of 10 lux, as recommended by the Singapore Land Transport Authority (LTA) for rural roads.
• Brightness adjustment: The lamp should dynamically adjust brightness to maintain consistent illumination, particularly during dawn and dusk
• Cost-effectiveness: The design should minimize costs to support wide deployment.

Technical Requirements

• Lighting color: Use neutral white LEDs

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• Flicker-free operation: Unaffected by brief or sudden external light sources.

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• Control functionality: Integration of an Arduino microcontroller (Uno)

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• DC-DC boost converter: Supply a steady 12V output to the load (LED array)

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• Risk / Opportunities​
• Functional block diagram​

Risk / Opportunities

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Risk / Opportunities

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Functional Block Diagram

Detailed Calculations�

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• LED
• Battery sizing
• PV panel

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• Illumination Calculation at 5-Meter Mounting Height

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• LED Selection and Practicality

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• Justification of Design

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• Energy Storage

• Capacity & Sizing

• Capacity & Sizing

• PV Panel

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Prototype & BOM

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• 3D model, 2D schematic
• Bill of Materials (BOM)

• BOM for Physical Prototype

• BOM for Theoretical Model

• Flowchart & Code
• Arduino brightness control

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Control Logic

• Flowchart for LDR Control

• Arduino Code

• Arduino Code
• Smoothing Using a Moving Average

• Arduino Code
• Rate-Limiting for Smoother Brightness Transitions

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• Arduino Code
• Combined Effect

• Testing Results
• Challenges & Solutions

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Testing & Challenges

• Photo of the Prototype Using Breadboard

• Photos of the Prototype Using Breadboard

• Oscilloscope captures under different input conditions.

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• (a) - (d) show images captured under 2.5V input condition.

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•  (e) - (h) show images captured under 5V input condition.

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• 70kHz

Challenges and Solutions

1. Heat Dissipation

• Challenge: After running for around 40 minutes, certain components, especially the MOSFET and capacitors, start to overheat, causing the LO output voltage to drop to 7.68V (from the expected 12-15V).
• Impact: The voltage drop affects the circuit's performance, leading to instability over prolonged operation.
• Solution: Allow the components to cool for about 1 hour, after which the circuit functions as expected. Additionally, for future iterations, consider using heat sinks or more efficient MOSFETs to improve thermal management and prevent overheating during extended use.

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2. Input Voltage Selection

• Challenge: Initially, the circuit didn’t function properly with a lower voltage input due to powering both the circuit and Arduino from the same source, which resulted in inconsistent behavior.
• Solution: Used a dedicated 5V power supply for the Arduino and powered the breadboard’s positive rail directly from the bench-top power supply (2.5V - 5.0V). This setup stabilized the circuit without needing any changes to wiring or code, ensuring consistent LED operation even at lower input voltages.

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Conclusion

• Summary
• Limitations & Future improvements

Summary

This project successfully meets the user requirements specified for a solar-powered street lamp suitable for an off-shore rural setting in Singapore. Each design aspect addresses specific user needs:

• The solar power system is designed to store sufficient energy during the day to power the lamp throughout the night, ensuring autonomous operation.
• Battery capacity calculations and testing indicate that the system can maintain illumination for up to two nights on a full charge, covering scenarios with limited sunlight.
• The lamp’s brightness is controlled via an LDR- based feedback loop, ensuring it lights up automatically in low-light conditions and maintains a consistent illuminance level.
• With LEDs rated at 130 lumens, the lamp achieves the 10 lux requirement at 5 meters, as recommended by the LTA for rural roads in Singapore.
• Cost considerations were prioritized, and components were selected to balance performance with affordability.

In summary, this project meets the technical and user requirements effectively, providing a robust and sustainable lighting solution for remote applications.

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Limitations & Future improvements

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• Weather Resistance: Although the prototype enclosure provides basic water resistance, long-term exposure to harsh weather conditions may impact durability. For real-world implementation, a fully waterproof and UV-resistant casing is recommended.
• Component Degradation: Components like the LEDs, battery, and PV panel may degrade over time due to exposure to environmental elements. Implementing a maintenance schedule and using industrial-grade components can mitigate this risk.
• Ambient Light Sensitivity: The LDR-based brightness control is effective but may respond inconsistently in varying lighting conditions, such as sudden headlights or shadows. Further calibration or a digital sensor upgrade could improve accuracy.
• Power Limitations: The prototype battery can last for approximately two nights on a full charge, but this duration may reduce with battery aging. Additional or higher-capacity batteries could extend operational time.
• Control Circuit Constraints: As the circuit complexity increases, such as with additional sensors or features, the Arduino's processing power and memory may become limiting factors. A more advanced microcontroller may be necessary for future upgrades.

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Thank You for Listening!

Demonstration and Q&A

Prototype testing under normal lab condition, with 5.0V voltage input

Final prototype testing after implementing:

1️⃣Smoothing using a moving average

2️⃣Rate-limiting step calculation

1️⃣As required, the DC-DC boost converter will step up the 5V supplied by Arduino to a high voltage around 15V (tested to be 17.6V) by adjusting the duty cycle of the PWM signal to be 65%.

2️⃣Then the 15V is input into the LIN pin of IR2110 MOSFET Driver, to modulate the current and voltage. 3️⃣Then around 13V (theoretically 15V) is output from the LO pin to be used for our LED array.

4️⃣Connect the LED array in series with the power resistor to adjust the brightness of the array using the principle of potential divider. 5️⃣Finally, the frequency of the PWM signal generated for the circuit for use is 70kHz (as the project requires a high frequency PWM signal of above 50kHz). And the voltage supplied across the LED array is around 11.8V, depending on the ambient brightness.

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We can fulfill all the requirements stated in the document. Most importantly:

1️⃣the LEDs turn off automatically when the preset brightness threshold is exceeded

2️⃣there is no/little effect of flickering shown when the brightness of the surrounding suddenly changes. As shown in the video (achieved by adjusting the Timer)

3️⃣the brightness of the LEDs vary based on the LDR value. Additionally, we can adjust the sensitivity of the LDR by connecting it in series with the variable resistor.

This corresponds to:

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1️⃣When the potentiometer resistance is at minimum. Least sensitive to ambient brightness variation.

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2️⃣When the potentiometer resistance is medium. Moderately sensitive to ambient brightness variation.

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3️⃣When the potentiometer resistance is at maximum. Most sensitive to ambient brightness variation.

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Use the benchtop power supply: the LEDs will only turn on with voltage input above 3.6V.

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Use a separate 5.0V voltage input for the arduino, and input a voltage to the circuit rails directly: the LEDs can turn on with voltage input of as low as 2.5V, and functions per normal at 5.0V.

2.5V Power Supply

5.0V Power Supply