Solar Powered Golf Cart Group 9 Jake Bettis Jacob Krueger Matthew Roland Matt Tourtelot With Support from:

Motivation ●Rapid growth in renewable energy, such as solar power, has caused a huge increase in the demand for engineers that know how to utilize these alternative sources of energy. ●With our project we are able to design and create an environmentally friendly vehicle while gaining first-hand knowledge and experience in a growing industry.

Goals To create and energy efficient golf cart that is capable of running on solar power and external outlet. A heads-up-display (HUD) will give the user options for different energy modes, navigational help, and status of golf cart.

Objectives ●Harvest energy from sunlight to power electric motor and onboard electronic systems ●Three modes of energy operations o standard, max performance, max efficiency ●Power monitoring system to display battery levels and check for battery storage defects ●Two user touch-screen displays o Display 1: power mode options, charge remaining, and current speed o Display 2: GPS system with map of current location and any necessary directions

Objectives Energy Modes ●Standard mode: motor will operate at 80% of maximum output and on-board electronics will be set at medium brightness levels ●Max Performance: motor will operate at 100% of maximum output and on-board electronics will be set to maximum brightness levels ●Max Efficiency: motor will operate at 60% of maximum output and on-board electronics will be set to low brightness The power monitoring system will automatically switch to max efficiency mode if the battery charge drops below 25% in order to conserve power for as long as possible

Specifications and Requirements 1.Must have a top speed of at least 15 mph 2.Must have 3 modes of operation which can be controlled by user 3.Must run off of a 36V or 48V battery storage bank 4.Batteries must be able to charge from solar panels or wall outlet 5.Must automatically go into power saving mode at 25% battery capacity 6.Must have two touch-screen displays for user information 7.Must provide navigational aid to user 8.Must provide charge remaining, power mode options, range left, and current speed

Budget PartEstimated Cost Motor Controller$600 Batteries$600 Charge Controller$150 Microcontroller(s)$120 Touch-Screen Displays$120 Sensors$150 Misc.$100 Total$1,840

Fully Connected System Diagram

Power System Components ●Solar Panels and Wall Outlet o provide power for motor and onboard electronics ●Charge Controller o Regulate power inputs from solar panels or outlet to the batteries o Implement MPPT algorithm to keep from overcharging and damaging the batteries ●Battery Bank o provide 36V battery supply

Power System Overview

Solar Panel

Solar Panel Electrical Specs Project design implements two panels connected in series. UnitQuantity Maximum Power P max 250 W Voltage at maximum power point V mpp 30.7 V Current at maximum power point I mpp 8.15 A Open Circuit Voltage V oc 37.7 V Open Circuit Current I oc 8.72 A Operating Temperature-40° C to +85° C *Specs are based on single panel at standard test conditions

Battery Supply

Battery Specs UnitQuantity Voltage6 V Amp hours (20 hour rate)232 Ah Minutes at 75 Amps122 min. Minutes at 56 Amps179 min. Minutes at 25 Amps474 min. Wet Weight Lbs.62 Lbs. U.S XC2 Deep Cycle Lead-Acid battery

Battery Specs Rate of discharge Batteries need to be able operate as long as possible while supporting different energy modes Consider the Current versus Discharge time

Battery Wiring We will be using six 6V batteries connected in series to obtain a 36V supply. The 232Ah will remain the same. Represented is the battery wiring configuration for the exact golf cart model we will be using.

Charge Controller Goal is to regulate voltage and current from solar panels to the battery to prevent overcharging Will implement a Maximum Power Point Tracking Algorithm (MPPT) This will find the maximum point on the I/V curve and track that point as sunlight conditions vary Works as a DC to DC converter Converts a high voltage DC to a high frequency AC, then back down to lower voltage DC to match battery supply Design will be based off of Texas Instruments TIDA-00120

Charge Controller Block Diagram Block diagram of Charge Controller system Based from TI evaluation board of TIDA MSP430 will implement a Perturb and Observe MPPT algorithm

MPPT P&O Algorithm Method is to modify the operating voltage or current from PV panel until you obtain maximum power from it P K = current power value P K-1 = Previously acquired power value Start Increase Operating Voltage Decrease Operating Voltage Is P K > P K-1 ? Yes No

Charge Controller Issues The reference design of the TIDA MPPT charge controller is based on 12-24V systems Our array will be based on a 36V system with a max V in of ~60V Solution: scale power MOSFETS to handle a higher system

HUD System Objectives ●Provide users with straightforward navigation around the UCF campus via GPS location. o Navigational map will be interactive and contain certain customizable features. ●Display the golf cart’s current speed, operating mode, and battery charge remaining. ●Allow users to easily switch between available cart operating modes.

HUD System Components ●Microcomputer ○ Provides platform for Android Operating System ○ Processes GPS and display signal input and output ●GPS PCB module ○ Outputs GPS coordinate information to the microcomputer ●Touchscreen Display ○ Provides user with display of the Android Application ○ Supplies microcomputer with user input

HUD Data Flow Chart

Microcomputer BeagleBone Black Raspberry Pi Market Price$45$35 CPU1000 MHz Cortex- A8 + 2xPRU (200 MHz) 700 MHz ARM1176JZF-S Video OutputsMicro-HDMIHDMI and composite video Power SourceMini USB, 2.1mm x 5.5mm 5V jack 5V via MicroUSB or GPIO header

BeagleBone Black Features Implemented ●Android Runtime Environment compatibility o Allows for the creation of a specialized Android Application o Easy Debugging ●HDMI video signal output o Allows video signal to be sent to the touch screen display while freeing up the USB input for the touch screen’s user input signals

Touchscreen Display HDMI 4 Pi: 5” Display w/ Touch and Mini Driver - 800x480 HDMI Tekit 619AHT 7” LCD Monitor Market Price$79.95$ Screen Size4.8” x 3.0”8.23” x 5.7” Resolution800 x 480 Display Ratio16:1016:9 Contrast300:1500:1

HDMI 4 Pi Display Features Implemented ●5V, 1A of electrical powered required for operation ●Receives video signal through HDMI connection o Micro-HDMI from BeagleBone to default HDMI port on the HDMI 4 Pi Display PCB ●Transmits touchscreen inputs through USB connection o Connected to the BeagleBone Black’s USB port for user gestures to be processed by the Android Application

MTK3339 GPS Module ●Sends GPS data pertaining to the current user position to the BeagleBone Black ●10 Hz update frequency ●Accurate to about 3 meters

GPS Module - PCB Schematic

GPS Module - PCB Design

GPS Module - PCB

Android Application User Requirements ●Access a navigational map that will track the user’s position and provide relevant information to user to help navigate around UCF’s campus ●Provide real-time updates on the cart’s power and speed ●Allow the user to switch between the cart’s modes of operation as they desire ●Create application settings that users can change from a settings menu

Android Application Development ●Developed within the Eclipse IDE using the latest Android SDK ●Many other inherent features of Java are used throughout the application design ●Tested for accuracy and reliability on every design prototype iteration

Android Application Class Diagram

UCF EzNAV Main Menu ●Very simple, intuitive interface ●The only screen that gives access to every created class ●Each button takes the user to a new screen within the app

Navigate Screen ●Interactive Google Maps Fragment ●“My Location” button and functionality ●Map markers for reference and building information ●License key for Google Maps API obtained through Google Inc.

Cart Status Screen ●Features updating data fields for cart information o Uses signals from the Motor Controller and GPS module to generate values ●Interface buttons that allow users to change the cart’s operating mode

Settings Screen ●Brightness slide bar allows users to change the display’s brightness ●Spinner selection list gives users the ability to change the marker colors in the Navigate screen.

Motor Controller Overview ●Pre-charge circuit prevents inrush current to motor controller ●ITS pedal outputs voltage from V with a 14V input ●Direction switch removes need for H- Bridge

Power Board

Power Board Schematic ●High current MOSFET’s ●On-Resistance of 1.45mΩ ●Capacitance ●Flyback diodes

Power Board BOM Part NumberDescriptionQuantityCostTotal IRFP7718PbFPower MOSFET LR821M200J uF capacitor STPS80150CWDiode N/APower Board Total

Motor Controller Logic MicrocontrollerTivaC 129XL Price (USD)20 Processor Speed (MHz)120 ADC Resolution (bits)12 PWM Channels8 QEI FeedbackYes Dedicated SPI/I2C PinsYes Flash Available1MB Low Power ModeYes PWM Hardware InterruptYes

Pedal ●ITS final decision

Modes of Operation ●Mode determined by user from touch screen

Voltage and Current Sensors ●Voltage and current sensors included to monitor battery power ●Power levels used to determine drive mode and remaining battery power

Progress

Final Steps 9-Feb16-Feb23-Feb2-Mar9-Mar16-Mar23-Mar30-Mar Order parts Create Android app Configure HUD Add V/I sensors Wire motor controller Wire charge controller Assemble cart Test features

Questions?