The Solar Tracker

Solar Tracking Project Team Members: –Cristian Ruvalcaba –Ken Seal –David Clark –Mark McKinley –Richard DeJarnatt

What are the objectives of the Solar Tracker? Have a solar cell that tracks the Sun as it moves across the sky

Why track the movement of the Sun? Because Solar cells only collect all the potential sunlight when the sun is directly over them

Stationary Solar Cell Limitation A Stationary Solar Cell is subject to the movement of the sun. Stationary Solar Cell Angle of Incidence Path of the Sun

How to track the Sun SensorAmp Micro Controller The Sun Motor Control

Determining the Relative Position of the Sun

Signals Generated from Sensor Shadows are caused by the moving sun on the dual panel photo sensor.

Amplifying the Differential Signal The two signals from the dual cell photo sensor will be sent to a differential amplifier.

Power Monitoring Both Power in and Power out will be monitored

Microcontroller Programming Micro-Controller –Inputs: Analog signal 0-5v from solar cell amplification circuit Limit Switches –Outputs: PWM motor signal Multiple signals for H Bridge Control –Microchip Development Microchip PIC chip –Uses assembly language or C for programming Solar Cell Differential Signal Motor Controller DC Motor Power

Control Strategies Problem: Correct error from solar cell: –Threshold Control System As the error breaks a set “Threshold” for error the microcontroller sends the signal to move the motor to correct. This is simple and allows the system to be in a energy efficient sleep mode. This is our feedback loop. –Limit Control Limit the maximum amount the motor can rotate so that there is no mechanical damage. Solar Cell Differential Signal Motor Controller DC Motor Power

PWM to Software H Bridge Receives a Pulse Width Modulated signal from microcontroller PWM Signal controls two transistors. Two other transistors are either “on” or “off” allowing for a directional change

H Bridge Receives Voltages and Control Signals Control Signals energize motor to turn in appropriate direction And at correct speed

Microcontroller Microchip 18F4520 –40 pin PIC chip –18 Familly Benefits 8 bit hardware multiplier 20 Mhz clock Software H-Bridge Aprox cost: $4.59 Enhanced Flash Memory Very “C” friendly hardware architecture

HMI – Human Machine Interface LCD –Menus Manual Mode –Right / Left Move Auto Mode –System automatically tracks the sun Power Management –Power used by electronics circuit –Power produced by solar cells –Power signals are produced from 2 voltage and 2 current signals. –When the circuit

HMI – Human Machine Interface LCD –Control 4 bit data and 3 bit control Keypad –Standard Row / Column 8 bit interface –Keypad enables the user to control system

Schematic

Movement Simulator

Power Management

ChargerBattery CPU + Motor Solar Cells

Questions…