Transcript Slide 1
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. Path of the Sun Angle of Incidence Stationary Solar Cell How to track the Sun The Sun Motor Control Sensor Amp Micro Controller 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. 5Vdc 1M 7 8 390 Sensor 3 To A/D Converter 6 4 1 5 2 + Sensor 2k 1M 2k 5Vdc Power Monitoring • Both Power in and Power out will be monitored Microcontroller Programming Solar Cell Differential Signal Motor Controller DC Power • 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 Motor Control Strategies Solar Cell • Differential Signal Motor Controller DC Power Motor 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. 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 A C B D H Bridge • Receives Voltages and Control Signals • Control Signals energize motor to turn in appropriate direction • And at correct speed A C B D 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 Power Management Solar Cells Charger Battery CPU + Motor Questions…