Home  |  Contents 
Windmills
  Forum Index : Windmills         Section
Subject Topic: F&P Electronic Dynamic braking Post ReplyPost New Topic
<< Prev Page of 3
Author
Message << Prev Topic | Next Topic >>
DaveP68
Senior Member
Senior Member
Avatar

Joined: 25 November 2014
Location: New Zealand
Online Status: Offline
Posts: 202
Posted: 05 July 2017 at 12:32am | IP Logged Quote DaveP68

Yep will go with that about starting them young, my little boy is 4 & 1/2 and already show lots of interest in what goes on in the work shop.

Wow tower climb with the young chap. Must say from photos you've posted, that's a great view from the top.

Can I ask what part of the US you're located in?

Also what timber did you make those blades from?

Cheers

David


Back to Top View DaveP68's Profile Search for other posts by DaveP68
 
kitestrings
Regular Member
Regular Member


Joined: 23 April 2014
Location: United States
Online Status: Offline
Posts: 76
Posted: 05 July 2017 at 3:25pm | IP Logged Quote kitestrings

We have four boys: ages 31, 12, 9 & 7. My youngest seems to be the most determined to "help". He's really into tools, jacks, things with engines and the like. I'm usually a stickler when it comes to safety gear - this is how I found on a recent day in the yard.

We're in the northeast corner of VT; aptly named the "Northeast Kingdom". We're about 20 mi. to the Canadian border.

We used balsam fir for our blades. If I was given a choice I'd probably use Sitka spruce, but it is not local. Balsam is locally available - we cut these logs and had them locally sawn, and air-dried - it is pretty strong for its weight, but is not as resistant to rot as say cedar.
Back to Top View kitestrings's Profile Search for other posts by kitestrings
 
DaveP68
Senior Member
Senior Member
Avatar

Joined: 25 November 2014
Location: New Zealand
Online Status: Offline
Posts: 202
Posted: 06 July 2017 at 10:29am | IP Logged Quote DaveP68

I thought you had sourced your supply of timber locally, good on you as that is the renewable approach for sure.

We travel to the US every 2 to 3 years and have family and friends in Pittsfield, MA not that far from your state. Next visit may try to look you up to pay a visit.

That's a wee bit of an age gap between the 4 boys. We only have to one at present.
Back to Top View DaveP68's Profile Search for other posts by DaveP68
 
gpalterpower
Senior Member
Senior Member
Avatar

Joined: 19 July 2009
Location: Australia
Online Status: Offline
Posts: 156
Posted: 12 July 2017 at 7:42am | IP Logged Quote gpalterpower

Hi Dave,
I been following this thread with some interest as I have always been looking for a way to control the sometimes "Out of Control" fan on my mill. The furling works ok, but I am all in favor of having a secondary backup to slow things down when wild weather hits. It is scary to see those blades spinning at break neck speed. Is your controller purely based on sensing over voltage, or can the system be incorporated with the R.P.S to slow things down. This would suit in my case as the mill is fed with a 24vdc supply. Marcus

__________________
if it aint broke dont fix it!!
Back to Top View gpalterpower's Profile Search for other posts by gpalterpower
 
DaveP68
Senior Member
Senior Member
Avatar

Joined: 25 November 2014
Location: New Zealand
Online Status: Offline
Posts: 202
Posted: 13 July 2017 at 8:24am | IP Logged Quote DaveP68

Hi Marcus

Thanks for taking an interest in this topic.

This dynamic brake circuit has been modified for 24 VDC operation but requires the IGBT switching device and dump load resistor to be in parallel multiples.

The trip voltage is set for say 29 VDC (adjustable) and the load resistors can be reduced to 5 ohms. You would need a minimum of 5x IGBT switches and 5x 5 ohm dump load resistors set up in parallel. All feed from the same drive transistor to each IGBT gate input.

This again is "Concept Only" and does not reflect an actual operational circuit!



The actual voltage trigger circuit would be some logic to trip then keep the clamp circuit on for the desired braking period. This could be minutes to say a few hours to said high winds have passed. Could also have an anemometer input to release the brake once winds have dropped to an operation level after a set period.

What are your thoughts?

David
Back to Top View DaveP68's Profile Search for other posts by DaveP68
 
gpalterpower
Senior Member
Senior Member
Avatar

Joined: 19 July 2009
Location: Australia
Online Status: Offline
Posts: 156
Posted: 16 July 2017 at 2:15pm | IP Logged Quote gpalterpower

Hi Dave,

Thanks for your help in adding to your original circuit diagram even though its still in the concept stage. I'm assuming there could still be a few bugs to iron out. Are you planning on testing one soon?

I like your anemometer idea, but would it be possible to somehow utilise the f&p speed sensor to just slow the mill down and not come to a complete stop. More like squeezing on the brakes to a useable speed. This way it could still charge, but not be out of control. Maybe too complicated

Marcus

__________________
if it aint broke dont fix it!!
Back to Top View gpalterpower's Profile Search for other posts by gpalterpower
 
kitestrings
Regular Member
Regular Member


Joined: 23 April 2014
Location: United States
Online Status: Offline
Posts: 76
Posted: 17 July 2017 at 3:05pm | IP Logged Quote kitestrings

Quote:
We travel to the US every 2 to 3 years and have family and friends in Pittsfield, MA not that far from your state. Next visit may try to look you up to pay a visit.


Normally I'd say that's a bit of a haul form where we live, but in relative comparison (to NZ ) it is quite close. By all means look us up if you can.

Years ago I worked for a wind small manufacturer that did induction, grid-tied turbines. They employed hydraulic braking early on, and then went dynamic braking. On the larger (40-50 kW) units they used electric water heater elements in free air as the resistive load. It worked quite well, but they also used "tip brakes" on the blades which were operated by centrifugal force if the rotor exceeded its operating range. This prevented run-aways in the event that there was a gearbox failure, or malfunction of the dynamic brake. It also added another maintenance item however.

I generally favor control strategies where the fail-safe mode is just that; something fails and the system shuts down. If you can incorporate that into the braking scheme it will likely work out best in the end. ~ks
Back to Top View kitestrings's Profile Search for other posts by kitestrings
 
DaveP68
Senior Member
Senior Member
Avatar

Joined: 25 November 2014
Location: New Zealand
Online Status: Offline
Posts: 202
Posted: 29 July 2017 at 2:31am | IP Logged Quote DaveP68

kitestrings wrote:
[QUOTE] I generally favor control strategies where the fail-safe mode is just that; something fails and the system shuts down. If you can incorporate that into the braking scheme it will likely work out best in the end. ~ks


Yes fail-safe mode is the best approach to take. What I'm proposing here is complementary to the fail-safe system that always should be there.

It's like having reverse thrust on aircraft jet engines which of course can fail to deploy on landing. But the wheel brakes are always there no matter what happens, just need to brake harder in an emergency if reverse thrust fails due to engine failure.

This dynamic braking idea is still only at a concept stage as I don't have a wind turbine to test it on. That's why I haven't bothered trying to make a fully operational unit yet as it requires more control circuitry to function on an actual wind turbine. So there no bugs so to speak Marcuus in this concept only circuit. It does what it was designed to do.
Back to Top View DaveP68's Profile Search for other posts by DaveP68
 
DaveP68
Senior Member
Senior Member
Avatar

Joined: 25 November 2014
Location: New Zealand
Online Status: Offline
Posts: 202
Posted: 17 September 2017 at 5:09am | IP Logged Quote DaveP68

The main reason I've been able to get good results from 'Power Factor Correction Capacitors' is due to the constant current control that this dynamic braking circuit provides.

Can now get up to 2.7 W per RPM peak from a single stator between 500 & 600 RPM.

When the optimum current is kept close to a constant value of 2.3 Amps from a 36 pole stator wired Delta, then the voltage can rise to the level required for maximum output power.

It's an easy circuit to build if you can get hold of a scrapped F&P motor control module.

Have been able to get more than a 1 kW out of my test stator using the module in the photo on the previous page. The catch is not to run the test for more than 10 seconds as the heat in the resistor gets the module VERY HOT!
Back to Top View DaveP68's Profile Search for other posts by DaveP68
 


If you wish to post a reply to this topic you must first login
If you are not already registered you must first register

  Search the forums using Google.
<< Prev Page of 3
In the news...
 
Post ReplyPost New Topic
Printable version Printable version
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You can vote in polls in this forum

Powered by Web Wiz Forums version 7.8
Copyright ©2001-2004 Web Wiz Guide

This page was generated in 0.0781 seconds.
Privacy Policy     Process times : 0, 0, 0, 0.08