1 PPR (or even 100 PPR) is just too low resolution
Hey Jon,
It's good to see you posting on this subject again. I followed your original posts when you were programming your
first plc controller for induction turbines. I was impressed that you were able to turn your project into a
business. Anyone here who is interested in the electronic control aspect of induction wind turbines would
likely agree with me that you have a lot of valuable experience of offer. I read your post and would have to
agree that 1 pulse per revolution would be a poor way to measure rpm if the hall effect sensor counted pulses.
It would be impossible to accurately control an induction generator turbine if this were the case, but it's not.
Your assessment that at 1800 rpm there would be 30 pulses per second is correct, but a single pulse is all that
is necessary to determine rpm. Instead of counting revolutions, the hall effect sensor, simply put, measures
the velocity of the magnet. So at 1800 rpm the breezy's hall effect sensor (with one magnet) is telling you the
rpm 30 times each second. Add another magnet 180 degrees from the breezy's single magnet and you will
get an rpm reading 60 times per second instead of 30. I don't know if it is better or worse for the wind turbine
application than the optical encoder you have been using, perhaps you can reevaluate the device objectively and
share your findings here.
This is why you either have:
A) An induction turbine that is inefficient in lower winds
B) An overly-expensive and overly-complicated hub design with pitch control. This gets around the problem of
being inefficient in lower winds, but puts it out of the realm of most hobbiests.
C) I haven't seen it personally, but a passive yawing system could work here - but keep in mind that even smaller
induction turbines easily weigh into the thousands of pounds - so engineering such a system could be a bit difficult as well
A) would define the breezy.
B) is my pet project. I'm attempting to design a (passive torque sensing torque regulating hub for use with an induction
motor/generator) that is minimally complicated that could be built at minimum expense. This would be torque regulating
only at first, to verify that it works, and if it does, centrifugal overspeed pitch feathering would be added. Yeah, it's a tall
order, but maybe not impossible.
C) one of the Jacobs induction generator type wind turbines does this. It has a 90 degree gearbox that steps up rpm and
turns a verticle shaft that powers a generator below the nacelle. This means the turbine is constantly trying to turn it self out of
the wind as the turbine turns, but the tail resists this action. The tail being spring loaded, allows the turbine to turn out of the
wind only when the torque becomes high enough to overcome the force of the springs. This turbine also has the classic centrifugal
pitch control hub as a safety feature in case of brake, gearbox, etc., failure.
They do have a place in alternative energy, but low wind speed areas and the hobby market haven't had a whole lot of experimentation
and there is a pretty big lack of information in this area.
I agree. And I know that in my wind zone, it might never pay for itself even if I build a reasonably good one on the cheap, but I'd still love
to have one. :-)
All that aside, apparently the breezy now incorporates a "soft start" device in their controls.
Can you shed some light on how this works? I read in one of your posts that some of the turbines you made controls for also have
a soft start feature.
Clint