1. Solar Array & Maximum Power Point Tracker Group Senior Design Project 2003 Stephanie Chin Jeanell Gadson Katie Nordstrom Advisor: Karen Panetta

2. What is a Maximum Power Point Tracker? The Maximum Power Point Tracker (MPPT) optimizes the amount of power obtained from the photovoltaic array used to charge the electrical power supply Why Design a MPPT? Our design is customized to meet the varying conditions of solar car racing, i.e. shadows, over-sun exposure, weather conditions, etc.

3. Basic Design The maximum power tracker unit includes the following components: Solar Array Power Supply PIC Microcontroller Analog to Digital & Digital to Analog Converters (ADCs and DACs) Pulse Width Modulator (PWM) Field Effect Transistor (FET) Protection Diodes DC/DC Converters

4. Solar Array A solar cell is a semiconductor device that absorbs the sunlight and converts it into electrical energy Power Supply The solar array charges 4 batteries at a time

5. PIC Microcontroller Operates the DACs and ADCs Computes the power point of the array according to the I-V curve. Regulates the Integrated Circuits (ICs)

6. Converters ADCs – Built into PIC – Changes the analog output of the solar array into a digital signal DACs – Translates the digital output of the PIC into an analog signal for the PWM

7. Pulse Width Modulator (PWM) Controls the FET Field Effect Transistor (FET) Our Light Switch Prevents overcharging of the batteries Determines the current paths between the solar array, power supply, and ground

8. Protection Diodes Prevent the current from flowing back into the solar array DC/DC Converters Boost and Buck Converters which power the ADCs, DACs, PIC, and PWM

9. System Specifications MPPT can handle Solar Array Input Voltage range 0-200v and max input current of 10A. The DC/DC Buck Converter steps down the Array voltage to 5v to power the PIC, DACs, and RS-232. Similarly, the DC/DC Boost Converter steps up the 5v input to 12v to power the PWM.