Solar Power-Optimized Cart (SPOC) Senior Design Project Documentation Due: April 28, 2014 Group #28 Members: Jacob Bitterman Cameron Boozarjomehri William Ellett SPOC Table of contents 1. Executive Summary1 2. Project Description 2 2.1. Motivation and Goals…………………………………………………………….2 2.2. Goals……………………………………………………………………………...3 2.3. Objectives………………………………………………………………………...4 2.4. Project Requirements and Specifications……………………………………..6. 2.5. Limitations………………………………………………………………………..7 3. Research related to Project Definition 10 3.1. Existing Similar Projects and Products………………………………………1. 0 3.1.1. SEV (Solar Electric Vehicles)..........................................................1..0.. .. 3.1.2. Tindo Solar Bus………………………………………………………...12 3.1.3. NUMA 7…………………………………………………………………13 3.1.4. UCF ZENN……………………………………………………………...14 3.1.5. EVOENERGY SOFLEX 600………………………………………….15 3.1.6. Star EV…………………………………………………………………. 16 3.2. Relevant Technologies…………………………………………………………17 3.2.1. Tesla Motors Rapid Battery Charging………………………………..1. 7 3.2.2. Grape Solar……………………………………………………………..19 3.2.3. Electric Energy and Power Consumption by Light­Duty Plug­In Electric Vehicles………………………………………………………..20 3.2.4. Battery Requirements for Plug­In Hybrid Electric Vehicles – Analysis and Rationale…………………………………………………………...19 3.2.5. Designing a High­Efficiency Solar Power Battery Charger…………21 3.2.6. Choosing a Microcontroller……………………………………………2. 2 3.2.7. Bluetooth Vehicle integration Components………………………….2. 3 3.2.8. Additional Bluetooth component considerations…………………….2.5 3.2.9. I2C and the Atmega328P­PU…………………………………………26 3.3. Strategic Components…………………………………………………………27 3.3.1. Cart……………………………………………………………………... 28 3.3.2. Atmega328P­PU……………………………………………………….31 3.3.3. User Interface…………………………………………………………...33 3.3.4. T105­H Signature Line Flooded Deep Cycle 6V Battery…………..3. 4 3.3.5. Solar Array……………………………………………………………...36 3.4. Possible Architectures and Related Diagrams………………………………39 3.4.1. Solar Array Architecture……………………………………………….3. 9 3.4.2. Motor, Battery, Micro Controller Integration…………………………4..0 3.4.3. User Interface Layout…………………………………………………..4.5 4. Project Hardware and Software Design Details 47 4.1. Initial Design Architecture and Related Diagrams…………………………..4.7 4.1.1. Photovoltaic Optimization……………………………………………...47 4.1.2. Drive Circuit……………………………………………………………..47 4.1.3. User Interface…………………………………………………………...48 4.2. Solar Array………………………………………………………………………48 4.3. Cart……………………………………………………………………………... 50 4.4. Power Control Subsystem…………………………………………………….51 4.5. User Interface Subsystem……………………………………………………..52 4.5.1. Hardware Components………………………………………………..52 4.5.2. Stretch Goals…………………………………………………………...54 5. Design Summary of Hardware and Software 56 5.1. Solar Cell Charge System……………………………………………………..56 5.1.1. Buck Converter…………………………………………………………57 5.1.2. Maximum Power Point Tracking (MPPT)........................................5..8.. 5.1.3. Panel Mounting and Adjustment………………………………………6.0 5.2. Battery Motor Integration………………………………………………………6. 3 5.3. Sensor Integration………………………………………………………………65 5.3.1. Photodetectors………………………………………………………….66 5.3.2. Thermistors……………………………………………………………...67 5.4. User Interface…………………………………………………………………...67 5.5. Microcontroller…………………………………………………………………..70 5.6. Vehicle Modeling……………………………………………………………….72 5.6.1. Normal Mode……………………………………………………………72 5.6.2. Performance Mode……………………………………………………..72 5.6.3. Eco Mode……………………………………………………………….73 5.6.4. Safety Measures………………………………………………………..73 6. Part Acquisition and Bill of Materials 75 7. Project Prototype Testing 77 7.1. Hardware Test Environment…………………………………………………..7. 7 7.1.1. Location…………………………………………………………………77 7.1.2. Ground Environment……………………………………………………77 7.1.3. Weather Conditions…………………………………………………….78 7.2. Hardware Specific Testing…………………………………………………….79 7.2.1. Solar Panel Testing…………………………………………………….80 7.2.2. Electric cart Testing…………………………………………………….81 7.2.3. Battery Testing………………………………………………………….81 7.2.4. Microcontroller Testing…………………………………………………81 7.2.5. Component performance Table……………………………………….82 7.2.6. Prototype testing………………………………………………………..82 7.3. Software Test Environment……………………………………………………8.3 7.4. Software Specific Testing……………………………………………………...84 8. Administrative Content 87 8.1. Milestone Discussion…………………………………………………………..87 8.1.1. Phase 1………………………………………………………………….87 8.1.2. Phase 2………………………………………………………………….88 8.1.3. Phase 3………………………………………………………………….88 8.1.4. Phase 4………………………………………………………………….88 8.1.5. Phase 5………………………………………………………………….89 8.1.6. Phase Calendar………………………………………………………...89 8.2. Budget and Finance Discussion………………………………………………90 8.2.1. Outside Funding………………………………………………………..90 8.2.2. Personal thanks to Duke………………………………………………9. 0 Appendices Appendix A­ Bibliography 92 Appendix B­ Initial PCB Schematic 96 Appendix C­ Initial PCB Board Layout 97 1. Executive Summary This project sprang out of a desire to create an electrically powered, cheap, efficient, and clean method of transportation for use over short to moderate distances. Many products currently exist that achieve the goal of electric transportation, but comparatively few of these use solar energy to dynamically charge while driving. As a result the project proposed had solar panels mounted both on top, and to the rear of the cart such that the panels could work in conjunction with the batteries to both charge and drive the vehicle. In addition, the vehicle did not need to be plugged in reducing the strain electric technologies place on metropolitan power grids. The primary objective of this project was the creation of a solar-assisted electric cart capable of recharging its own batteries via the sun’s rays. This objective included several secondary objectives that were dependent partially on efficient use of funds. The clearest method of evaluating the completion of the primary objective was by the vehicles ability to charge while driving, and to compare its performance to its none solar counterparts. Elements such as range were affected by a number of other attributes, such as solar cell efficiency, electrical system design, multi-mode operation, as well as the quality of the parts in used for the projects construction. Designing and building a vehicle like this had a powerful impact on the way American consumers traveled between locations in urban and suburban settings; particularly in large cities or other close-packed communities. The large majority of commuters use fossil fuel driven vehicles of disproportionate sizes to traverse short distances, where the vehicles would then sit in wait while in disuse. The project intended to counter this imbalance by providing a smaller, more maneuverable vehicle that would spend the time it was not in use collecting energy. The solar cells would allow for charging without the cost of additional infrastructure, appealing to both consumers and communities alike. However this dynamic design for charging such a vehicle proved to be a complicated proposal. It became necessary to set specific milestones to ensure continuous progress throughout the course of the project. Each stage on the project timeline is discussed in greater detail in Section 8. These stages were individually significant while keeping the scope of the project in focus. Primary goals were that this project achieve: environmental sustainability, market feasibility for a maximum number of viable consumers, power optimization for increased range, and financial minimization to stay within our desired budget. 1 of 97 2. Project Description This section goes about explaining what the primary focus of many of our project elements were. It also further tied in what motivated us to approach the project in this manner. Primary concerns for this section included how to distinguish our project from its non-solar counter parts. We also emphasize that this project, while still a proof of concept, is laying the groundwork for what could be a revolution in human transport in urban areas. 2.1 Motivation Our team has desired to confront a series of problems common to cities across the globe. For centuries, cities have struggled with pollution from fossil fuel driven technologies. Since the invention of the internal combustion engine, global urban air environments have grown thick, dirty, and unhealthy. Gasoline-based engines still exist as our primary source of transportation. The development of electric cars has come a long way, and ideally will be the key to not only more efficient, but all around better human transportation. However current electric vehicles indirectly depend on fossil fuels to charge. The potential to take these vehicles off of the city grid, and integrate them with solar technology would both reduce the load on city grids, and improve vehicle performance by carrying their fuel source with them. Transportation in America has become terribly inefficient, specifically within densely populated regions. Americans live with privilege and prosperity, but this has created unnecessary issues in our transportation systems. We transport 100 people within a city in a little less than 100 cars, trucks, or vans. The design of our streets and the dense population of the city does not allow for this ratio of people to cars. There are two obvious solutions: maximize the number of people per vehicle or minimize the “footprint” of the personal transportation. The advantage of this second solution relates to the individual autonomy of private transport that Americans strongly cling to. Our team decided to approach