Author Topic: Large Parabolic Trough Tracking  (Read 1879 times)

darcyd

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Large Parabolic Trough Tracking
« on: July 16, 2013, 05:33:36 AM »
Hi All,
Iím in the process of planning a large-ish parabolic trough (around 40 square meters) which would require some reasonably heavy-duty tracking gear. I have no experience with stepper motors or arduino so have a few - probably hundreds of - questions:
Can the sun harvester shield be used (as is) to control large (NEMA 34 1694 oz-in) stepper motors with the appropriate motor drivers?
As I have no experience with stepper motors I have no intuitive understanding of their torque/power but it seems to me that the larger steppers coupled to reduction drives/gearboxes would be capable of moving and holding a 40 sq meter trough in average winds. Any advice here?
Darcy


Gabriel

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Re: Large Parabolic Trough Tracking
« Reply #1 on: July 17, 2013, 07:29:34 AM »
Hi Darcy,

The Sun Harvester shield shouldn't have to be modified to control larger driver boards. Just so long as it is a step / direction type driver board that runs off of 5V signals, it should be fine. Sid's setup is the largest I've seen that uses this project, but it sounds like yours is even larger still!
http://www.cerebralmeltdown.com/wp-content/uploads//2011/07/Solar-Panel-Tracking-Electronics.jpg

I think these are the stepper motors he is using (212oz-in).
http://www.interinar.com/4023-833.html

and this is the driver board
http://www.circuitspecialists.com/cw230.html

That example might at least give you some "intuitive understanding of their torque/power".

I guess we would need a better idea of what design you want to build though before we can nail down the electronics.

Something else to consider too is that the Sun Harvester Program isn't currently setup to control a parabolic trough. I don't think (???) that it would be too difficult to modify it to make it operate as one though. I've just never had access to one to test code on.

Gabriel


dave-in-NJ

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Re: Large Parabolic Trough Tracking
« Reply #2 on: August 28, 2013, 05:00:59 AM »
sorry to see this end after one post..... 
I too am working on a trough.
as I see it, I need to have elevation and rotation, not azimuth.
if one considers the sun, the target and the mirror to be in a flat plane, the axis of the mirror needs to rotate.
I have been having a hard time with the worm gear cutting.  using threaded rod that I cut cutters into with a dremel. 
I have an arduino powered and using simple pulsing, was able to move the motor, not up to loading the program and tracking yet.

so, my question would be about converting the azimuth based on angles of rotation of the mirror and not just the rotation of the planet in relation to the sun.  I can see it is possible, but have no clue as to the math.

Gabriel

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Re: Large Parabolic Trough Tracking
« Reply #3 on: August 29, 2013, 06:49:04 PM »
I don't have much experience with parabolic troughs, but the way I understand it is that they typically use the sun's declination and hour angle for positioning. Both of these values are already calculated in the Arduino program since they are ultimately what is required for calculating the sun's altitude and azimuth. I don't think that it would be too hard to cheat and just plug in the declination (with the latitude value added in somehow) and hour angle values in place of the sun's altitude and azimuth.

There might be more to it than that though. How is the geometry setup for your machine? I know that there is more than one way that parabolic troughs track the sun, which means you would have to do different things to the code to make it work depending on your design.