Platform 2: Renewable Enery

Project 5b: Green Bike Generator

Introduction

With everything going green nowadays, bicycles are no exception. There has been a rapid growth for electric bikes (e-bikes) since 1998, otherwise called green bikes. Europe, especially, is a large market for these bicycles, which are a type of motorized bicycles. Denmark, for instance, has hotels where guests can pedal on a row of green bikes to generate power to the hotel grid, then, actually get free meals or services for the equivalence of their produced power. Now, Asia is also starting to pick to pick up this trend. China alone is estimated to have 120 million green bikes in 2010, exceeding motorcycles or conventional bikes in urbanized regions.

Project History

This green bike project was started a year ago in the electronics lab at the University of Ottawa. A few electrical engineering students were working on generators with a researcher in the lab and they had the idea of applying it to a green bike, since they are so popular. Then, the project was brought to ARISE, the faculty’s Advanced Robotics Innovation Society of Engineering student club, where it became a project. This project is a mix of mechanical and electrical, as well as controls, hence, it’s a typical product of the growing field of mechatronics.

Final Product

Similar to the Denmark hotel, your final product will be a bicycle that can be plugged into the wall to return power to the grid. You will have to analyze two situations, one where the generator used is an AC generator and the other where the generator is a DC generator.

Your final product should also display whether the generator is producing power or not, RPM as well as Watts being produced while the user is pedaling. After the user’s session ends the kWh produces, the calories consumed and the session length should all be displayed. This display should be packaged into a simple user interface.

Tasks

Students are divided up into teams of 3. All groups are given the same tasks, so that each group can cover the mechanical, electrical and controls aspects to learn all of them. There are 2 options: your group can either do the AC generator system or the DC generator system. All the tasks are the same; the DC option has an extra step. The following are tasks to complete, in order to complete this e-bike project:

1) The first task is to determine what kind of input the average human will give to the bike. This data includes pedaling speed as well as power input. It is obvious that the answer will be a range of speeds and power so this range should be matched to the speeds that are on the bike (18 speeds). This data can be collected through observation at your local gym or referenced to studies from credible sources.

2) Gear Ratio – There is a certain gear ratio (from the feet that are pedaling to the generator that’s turning) that makes the system switch modes, and you must find that correct ratio to get the bike from motor to generator mode. Note that the ratios for the AC and the DC groups will be different.

3) Physical Setup - Design and build a setup for the generator system to fit onto the bike, from the tire to the generator. It should be stable when you are riding. (Try to put a low centre of gravity).

4) Monitoring System – Design a controls system to enable the generator to switch on and off when the rpm is correct (make sure you did step 2 correctly). Then, implement a monitoring system such that it displays watts, rpm, and the bike mode (either generator or not) at the minimum. However, you are encouraged to also display the voltage, current, and power factor. After a user’s session has ended (the interface can be designed as you please) the energy produced in kWh, the calories consumed and the length of the session should all be displayed.

5) DC to AC Power Conversion (*For the DC group only) – now that you produced power from your DC generator, supplying this to the grid needs the use of power electronics to convert the power the AC. For this, you should check out your local power authority’s standards for grid supply.

Schedule

The schedule is divided into tasks and the project will be spanned over 2 months.

Tasks 1 and 2 should take, cumulatively, 2 weeks to complete.

Task 3 should take about 2 weeks. It is suggested that you make complete drawings of what you are going to build before you do so.

Tasks 4 and 5 as well as writing a report on your project should take the rest of the time you are given.

Good luck J