I just found this forum
As a hobby project I've been building my own bicycle engine and engine controller (both from scratch
using of the shelf stuff like magnets, an iron bar and some sheets of aluminium and using only
tools like a simple drill and a jigsaw).http://www.youtube.com/watch?v=dGfrcnu5J-I
(There's a second video where it spins up to around 900 rpm @ 67 V)
The engine is supposed to be build onto the luggage carrier of my bike with a chain going
down to a sprocket (attached to spokes) on the left hand side of the wheel. The axle of
the engine is actually a shimano deore rear-axle, this gives me bearings, freewheel, easy attachment
of a sprocket to the engine and I have a wide range of choises for the transmission ratio. The
rotor of the engine is attached to the axle by 32 screws going through the (drilled out) spoke holes.
The controller is build around a general purpose PIC 16F88 processor (a component which does not
have a motor controller in it) running around 300 lines of code (assembler). There are no
hall or optical sensors, its a sensorless design.
For smooth and constant torgue I am planning to drive the engine not from a voltage source but
from a current source using a DCDC converter and a (different from standard) control loop. Battery
will probably be relatively low voltage, 18V. I'm not planning to use PWM or sinusoidal PWM as found
on commercial bikes
As a small introduction, I am 39 yrs old, Dutch (so excuse my english) and live in Switzerland. I am an
analog / mixed signal design engineer by trade (basically an electronics engineer who designs IC's,
I mostly do ADC's, DAC, amplifiers and stuff like that).