Showing posts with label electric vehicles. Show all posts
Showing posts with label electric vehicles. Show all posts

Saturday, September 13, 2008

Electric Motorbike Update

Here's an update on the electric motorbike project:


(Yes, it's crap quality, a better one will be uploaded soon.)

The back wheel hits 100mph with no load on the bike.

The battery rack:
Next we will be adding the batteries onto the frame and implementing a pwm throttle.

Thursday, June 26, 2008

Electric Motorbike Conversion

Old Bike Frame
+

Forklift Motor

=

Vroom!
...it will probably be more of an electric-sounding whine. Anyways, the motorbike was stripped of its engine, gas tank, transmission, and the rest of its innards. The forklift motor was pulled out of a dead forklift. A basic prototype using a different bike frame and motor was demonstrated at the last Maker Faire. When this thing is finished, it will make for one hell of a stealth bike, and will eventually make use of those heatsinked mosfets in the UPS's as explained a couple posts back. Here is a pic of the older version, which is using a different frame and motor:


Wednesday, June 25, 2008

UPS's, MOSFETS, PWM and more!

This post will discuss an idea related to the circuitry inside UPS's and a possible application. Now I don't take credit for this idea, I am posting it here to get input on whether you/readers think it is feasible, or have any suggestions on its implementation.This is a picture of the circuit board of a UPS. There are many dead UPS's lying around the ACCRC.
This is a closeup of a bunch of the heatsink, which cools off a group of mosfets wired in parallel, the main current shifter. Each one of these mosfets, an irf3710, is capable of dissipating 50 watts. (according to the irf3710 datasheet) So together, they can supply 1000 watts, easily enough for a powerful motor.

The idea is to take these mosfets, and use them as the basis for a scalable high-wattage motor controller. When I was building a robot (more on that in a later post), the hardest part of the initial hardware design was getting a motor controller circuit which could put out suitable current to drive the motors. Motor controllers are expensive, and the lack of them is the main restricting factor of a lot of the electric vehicle/robot work that goes on here. Anyways, the mosfets would be wired in parallel, allowing for scalability. They would take input from a computer or a microcontroller which puts out PWM, like the arduino board, or the circuit based off a parallel port, as described at http://lukecole.name/parallelport_pwm_driver.php.

Combined with easy pwm circuitry, these mosfet arrays will make it a heck of a lot easier and cheaper to conduct robotic and electric vehicle research. Any questions/suggestions?