ECE 110/120 Honors Lab Section : Automagic Bike Phone Charging System

Created by Sokolowski, Stefan, last modified on Sep 23, 2020

Stefan Sokolowski - stefans2 - ECE 110 , Oliver Johnson - owj2 - ECE 110, Griffin Rzonca - grzonca2 - ECE 110, Carlos Paredes - cfp3 - ECE 120

  1. Intro
    1. Statement of Purpose
      1. Our project aims to harness the mechanical energy generated by pedaling a bike, and convert some of it into electrical energy to be used to charge personal electronic devices such as cell phones, headphones, laptops.
    2. Background Research
      1. From our research we have determined that BLDC three phase motors are most efficient in generating but they will require a low KV number and a high gearing ratio in order to properly convert the kinetic energy of the bike to electrical energy at a high enough voltage to be useful in our charging circuit. We will be shooting for 5 V of power at medium to low speed on the bike. We will be creating a BMS system for the components integrated into the battery bank circuit. It is imperative that the cells don't drop below 3V and don't go over 4.2V, or we could be dealing with some explosive results. We will most likely be using either a pre-made battery bank module widely available on the internet because of the sheer amount of features it has (Quick-charge, USB-C, etc) or designing a circuit around a battery bank IC we find. We also need to make sure our BLDC motor has a proper KV rating and gearing so that we get a usable voltage out of it and can draw a decent amount of power from it. There are many options for motors out there but we would probably want about 10 Volts at about a 100rpm to have a good bike compatible motor.
  2. Design Details
    1. Block Diagram / Flow Chart
    2. System Overview
      The BLDC Motor and Gearbox will convert the kinetic energy of the bike into electrical energy which will then go to our filtering circuit. The filtering circuit will take the 3 phase shifted sine waves of the BLDC motor and produce a DC voltage. This variable DC voltage will then be passed into the charging circuit which will feed the battery bank circuit which will charge the batteries in a controlled manner and allow discharge of them at a regulated 5V level for most modern cell phones and tablets.
  3. Parts and Estimated cost

    1. 1 Bike - Free (Somebody's got one)

    2. 1 BLDC Motors with gearing - $40

    3. 4 18650 cells - $12

    4. Diodes for Six Pulse Rectifier - $5
    5. Passive components for circuitry - $25
  4. Possible Challenge

    1. Making sure the motor is compatible with all bike models.

    2. Generating enough kinetic energy in the bike to get a decent charge.

    3. Getting good filtering from the 6 pulse rectifier

  5. References

    1. https://www.youtube.com/watch?v=cJ_vDA7xsGs 

    2. https://www.eleccircuit.com/unregulator-power-supply/


Attachments:

image2020-9-17_18-27-6.png (image/png)

Comments:

For each team member, please include the class you're currently taking (ECE 110 or 120).

Have you done any research on a Battery Management System (BMS) to properly manage charging? You will need this if you don't want to risk overcharging your batteries and causing an explosion. If so, please include that in your project proposal.

Please also list the quantities and costs associated with each of your parts.
Posted by jamesw10 at Sep 19, 2020 22:53

Good job on the proposal, but a few comments:

-Make sure you do your research on BDLC motors- there are many kinds of them, and each comes with some quirks and compatibility particulars with the other components. 

-Be sure to get a charge controller for your battery that can handle the all the varying power/voltage output from the pedals. See if you can come up with some estimates for the power/voltages your components may be seeing so it's easier to find the right parts.  

-There are a bunch of youtubers that have designed mechanisms for connecting dc motors to bikes (PeterSripol and Tom Stanton pop up immediately to my mind)- thier projects, while having a different purpose, may help you with your mechanisms. 

-Other than that, it's a great idea-should be fun to see in action!
Posted by siva3 at Sep 19, 2020 23:30

BMS is a pretty advanced topic. Please do your due diligence to ensure safety and lack of explosions! (smile)

As long as you do your research on BMS, this should be a great project. Approved. (Swamy's comments on checking out Peter Sripol and Tom Stanton are VERY good. Tom Stanton has some great stuff on mounting motors to bikes.)
Posted by fns2 at Sep 30, 2020 16:09