Conceptual Design Presentation Electric Bike: ECE Group 6

Presentation Overview Introduction Charging Method 1: Wireless Charging System Wireless Charging System Proof of Concept Test Charging Method 2: Physical Connection Charging System Locking Methods Conclusion

Introduction Justin Hatcher

Sponsor Overview Project Sponsor – Efficient Systems LLC. About Efficient Systems, LLC: Tallahassee start-up company Developing an electric bike sharing program Focused on reducing carbon footprint Focused on reducing traffic congestion

Electric Bike Overview Electric bicycles are bicycles with an integrated electric motor The motor can be engaged manually through use of a throttle controller This allows the rider to travel quickly and comfortably E-Bikes sharing programs are gaining popularity around the world As of 2010: 120 million E-Bikes were reported in China 700,000 new E-bikes were sold in Europe

Problem Statement To create a docking station capable of charging and securing E-Bike’s that requires minimal user interaction Major Challenges: How to charge the E-Bike’s? How to securely lock the E-Bike’s? How to minimize user interaction with the docking station?

Project Overview Project Current State: Major Project Goals: Inconvenient docking method Inconvenient charging method Major Project Goals: Develop a charging method that requires minimal user interface Develop a locking method that requires minimal user interface Incorporate the developed methods created into the docking station

Needs Analysis The E-Bike docking station should: Be able to efficiently charge an E-Bike within 4 hours Be able to securely lock an E-Bike using a mechanical lock Utilize a front facing docking method Require minimal user interaction Be able to operate in adverse weather Be modular and aesthetically pleasing Be cost-effective

Project Design Approach

Charging Method 1 Hassan Aftab

Charging Method 1: Resonant Inductive Coupling Midrange wireless transmission of electrical energy Uses two self-resonant coils with internal capacitance The magnetically coupled coils are set to resonate at same frequency Allows for further transfer of power versus standard inductive coupling Distances of up to 10 times the diameter of inductive coils Study done by MIT allowed for self-resonant coils to transfer 60 W at 10 MHz over 2 meters at 40% efficiency

Charging Method 1: Resonant Inductive Coupling

Charging Method 1: Design Flow Chart

Charging Method 1 AC power drawn in from main electrical line (120-240 V, 50-60 Hz, 140 W) rectified to DC Voltage-controlled oscillator used as an electronic oscillator to produce a periodic, oscillating signal Frequency amplifier to adjust signal frequency so that it matches the resonant frequency of the sender and receiver inductive coils Sender coil directly connected to the circuit within the station, receiver coil mounted on electric bike

Charging Method 1 Both coils are magnetically coupled and tuned to resonate at the same frequency Power transfer will occur between the two coils within a near field AC power taken from receiver coil will be rectified to DC DC power will be used to charge lithium-ion battery mounted on the E-Bike Directly connected to lithium-ion battery via a male 3 pin XLR connector

Charging Method 1 Advantages: Disadvantages: Requires no user interaction Weather resistant Minimal risk to damage power transfer connections Disadvantages: More complex design More expensive design Lower power transfer efficiency compared to Charging Method 2 Potentially could causes higher energy costs and slower charging

Charging Method 1: Proof of Concept Test Xiaorui Liu

Charging Method 1: Proof of Concept Test Diagram

Charging Method 1: Proof of Concept Test Results Resonant plates fundamental frequency: 135 MHz – 145 MHz When resonant plates were ideally coupled a Port 1-2 transfer of -2.91 dB was achieved Conversion Formula: 𝑑𝐵=10 log⁡( 𝑃 𝑟𝑒𝑐𝑖𝑒𝑣𝑒𝑑 𝑃 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟𝑒𝑑 ) Power received over power transferred is equivalent to the percentage of power that was transferred from Port 1 to Port 2 -2.91 dB is equivalent to a 51.17% power transfer

Charging Method 1: Proof of Concept Test Improvements Areas to be improved: Increase the efficiency and effectiveness of the induction coils Increase the efficiency and effectiveness of the resonant plates Reduce the fundamental frequency of the resonant plates Expected results when improvements are made: Increase in power transfer efficiency well above 50% Significantly increase the distance between the resonant plates at which power can be efficiently transferred

Charging Method 1: Research There is a push to have an international standard for wireless power transfer applications that transfer over 5 W of power This comes in part from the automotive industry The push is for the frequency of wireless power transfer to be 85 kHz Evatran LLC has created an induction based wireless power transfer application for the Nissan Leaf and Chevy Volt The system is capable of charging the Nissan Leaf in 8 hours and the Chevy Volt in 3 hours The system supplies 7.68 kW of power at 240 V and 32 A

Charging Method 2 Gabriel Sejas

Charging Method 2: Physical Connection Flow Chart

Charging Method 2: Design Plans

Charging Method 2 Advantages: Disadvantages: Efficient charging system Requires no user interaction Simple and effective design Potentially more reliable than Charging Method 1 Cost effective Disadvantages: Potentially easier to damage plug connections Potentially less weather resistant than Charging Method 1 Potentially more difficult to design a mechanical locking system with charging functionality included Mechanical locking system will need to position the E-Bike precisely in order to achieve ideal coupling

Locking Method Overview Elijah Goodson, Hunter Harrison

Locking Mechanism Needs Front end loaded locking mechanism Autonomous Weather and corrosion resistant Relatively inexpensive Relatively lightweight Modular design

Bracket Design With proper material selection the current designs will be cost effective The design easily modifiable to be placed on future iterations of the bicycle Can incorporate either charging method inductance or charging cord, however different bracket shape will be necessary

Bracket Design: Option 1

Bracket Design: Option 2

Station Design

Material Selection: Aluminum 2024-T3 Strength High strength to weight ratio Machinability Ductile metal Does not require special machinery to fabricate Element Content Wt. % Aluminum, Al 90.7 - 94.7 % Chromium, Cr 0.1 % Max Copper, Cu 3.8 – 4.9 % Iron, Fe 0.5 % Max Magnesium, Mg 1.2 – 1.8 % Manganese, Mn 0.3 – 0.9 % Silicon, Si Titanium, Ti 0.15 % Max Zinc, Zn 0.25 % Max

Material Selection: Aluminum 2024-T3 Cost Low cost ($0.71 per pound as of October 14) Life Relatively corrosion resistant Can be made virtually corrosion free Priming and painting Anodizing

Conclusion Justin Hatcher

Decision Matrix Categories Transfer Efficiency Design Simplicity Cost Efficiency Tolerance Level Totals Values 10 6 8 7 # Charging Method 1 50 24 87 Charging Method 2 90 48 64 209   Wireless Bracket 70 30 72 14 186 Plug Bracket 35 219 Clamp Claw 80 42 40 204 Deadbolt 56 244

Docking Station Design Research Docking Station Prototype Construction Project Timeline Today Week 1 2 3 4 5 6 7 Finalize Docking Station Design 10/30/2015 Midterm Report Complete Research and Development on Docking Station 11/13/2015 Purchase Materials for Docking Station 11/20/2015 Final Webpage Design 11/24/2015 Final Report 12/1/2015 Begin Prototype Construction Midterm Presentation 2 11/19/2015 Poster Presentation 10/22/2015 Docking Station Design Research Docking Station Materials Research Docking Station Prototype Construction

Questions?