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VT_Ebike

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Members

  • Oscar Alarcon
            Electrical Engineering 
            aoscar@vt.edu

Mentors

  • TBD

Current Status

  • First prototype is under construction

Project Overview

Every day, electrical bicycles are becoming more common in densely populated areas and cities, such as, Northern Virginia and New York. They are becoming a desirable form of transportation to avoid dealing with heavy traffic, parking struggles, fluctuating gas prices, and green house gas emissions. The goal of this project is to build an electrical bicycle that can be a safe, low-cost and reliable form of transportation, while delivering high energy efficiency. 


Tasks

  • Research different types of motor drives for bicycles and determine which option will deliver the highest efficiency.
  • Research the composition of possible battery types that can be implemented. 
    • Factors to keep in mind:
      • Battery life
      • Battery capacity
      • Weight of the battery pack vs charge capacity
      • Rider's safety (In extreme cases batteries can cause unwanted/dangerous chemical reactions) 
      • Battery cost
    • A lower-cost viable solution would be to build a battery pack using 18650 cells
      • These cells are known to be reliable and have a longer life
      • Safety concerns regarding the temperature of the battery pack can arise
      • Welding the cells together has its own risks
  • Research on a method to waterproof sensitive electronic controls, and LCD display.
  • Decide what type of braking system will be most suitable for the bicycle 
    • Disk Brakes
    • Rubber pad brakes
  • Decide on motor controls
    • Braking system sensor (disabling the motor)
    • Pedal Assist System (PAS) vs twist throttle
    • LCD display type
    • Lighting instruments (headlight/backlight) 

Educational Value Added

I am learning how to build an electric vehicle strictly following safety guidelines, as well as making it a reliable vehicle that delivers high energy efficiency and extended battery life. In the design of the system, key issues will arise regarding specifications, design implementation, and rider's safety. Such design challenges will give me an insight of what king of issues also arise in the industry. The design will have to prioritize the rider's safety over any other factor.


Design Decisions

Decisions which were made about the design and should be documented 

Decision 1

To improve the bicycle's suitability for cities the motor will be a 1000W direct drive hub motor. It will deliver the highest torque efficiency, while effectively using the battery charge.

Decision 2

Disk brakes will be used in both tires. Disk brakes are the most cost efficient braking system that can be used on the bike. Unlike rubber braking pads, disk breaks will not wear out as fast and will improve the braking distance for the rider.

Decision 3

TBD

Design Misc.

Other information about the design, parts used, etc.

Parts

  • A12v 8" LED floodlight will be used as headlight. This was the best pick given its weight, lighting capacity, and energy consumption. It is very important for the rider to have good visibility at night.
  • Both a twist throttle and a Pedal Assist System will control the bike's speed. The rider can choose between putting in minimal effort or pedaling along to extend the battery life.

BOM + Component costs



Timeline

I have already spent about four months doing research on my free time. 
During December 2017, I installed the brushless motor on the back tire, as well as installing electronic controls.
Most design decisions are defined at this point. 
The next big thing on the to-do list is the battery  

Useful Links

  • http://www.batteryspace.com/
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