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The Projects Forum Working on an electronics project and would like some suggestions, help or critiques? If you would like to comment or assist others with their projects, this is the place to do it.

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  #1  
Old 04-16-2012, 10:56 PM
ocelot28374 ocelot28374 is offline
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Join Date: Apr 2012
Location: Wyoming
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Default Wind generator breaking circuit

I am having a problem with my off grid wind generators. The "moderately" high winds in wyoming are wreaking havock on my turbines. I have burned up 12 turbines from the built in breaking action of commercial controllers and over speed.

I have a background in troubleshooting but not design. I am a technician not an engineer.

My system is 24 volts DC, 27 volts float, 28.4 volts Bulk charge. I would like to use this voltage variable to control an electromagnetic breaking device on the turbine rotor. with no application at 27.0 volts and adjustable application at 28 volts and higher to reduce turbine output and prevent over speed when the battery system has reached full charge.

This would have immediate commercial applications to which I have no interest. I would just like access to test and use the design.

The circuit should have adjustable input variables and adjustable output current.

I hope someone can help me with this challenge. Contact me with questions, I can provide pictures of the turbines i will use for testing and help with physical design. I can also help with concept.

Thank You
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Old 04-16-2012, 11:21 PM
Felo Felo is offline
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Hi, I am just thinking out loud here but I find this very interesting, tell us how does the built in break woks, (or pictures of it) is it a mechanical device like a motorcycle break? (I have no idea I'm just telling something).

But then a vehicle break with hydraulic pump action may be just what you need, it should be easy to build a "electric push rod" with threads and nuts and control it by monitoring the voltage output of your turbines.

Another thought is to attach a dc motor with a "upper H" PWM drive as to control not the speed of the motor but PWM control it's breaking action.

Does these turbines have a "high side" spining speed limit? are the winds there so strong as to destroy the turbine if left spining free with no breaking action? the excess energy can be dealt with by making a SMPS wich can take a huge voltage and then regulate it for you at desired levels.

Just a few ideas
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Old 04-16-2012, 11:27 PM
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#12 #12 is offline
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Is the basic concept to redirect the excess energy so it works against the velocity of the blades?
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Old 04-16-2012, 11:28 PM
wayneh wayneh is offline
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Search on wind BRAKING. This is at least the second thread on this topic in the last month.
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  #5  
Old 04-17-2012, 12:27 AM
ocelot28374 ocelot28374 is offline
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most common small wind turbine controllers brake the turbine by shorting out the coils in the stator, other controllers accomplish loading the turbine by applying a diversion load in place of the battery bank or in parallel to the battery bank. what I would like to accomplish is physical braking of the turbine with a current controlled device such as an electromagnet with spring loaded rollers to apply resistive force to the rotation of the rotor without stopping it. this would effect a change in output current from the turbine that would limit the applied charge current automaticaly allowing the turbine to opperate in high wind conditions at much lower RPMs than the diversion load would allow as well as preventing the turbine from burning up from an exess of current from the stator coils or burning it up by trying to stop or slow the turbine by shorting out the coils. both situations I have encountered already. Also, brake pads applied by mechanical force wear out quickly and must be applied by hand. by using a device such as described the turbine would be prevented from overspeeding by physical force but not applied by manual means.
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Old 04-17-2012, 12:37 AM
ocelot28374 ocelot28374 is offline
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wayneh, Thank you for the search topic. I found a few threads but they seem to deal with shorting the turbine. in high winds this has always resulted in terminal damage to the stator. I am always looking for way to make improvements to my system, any advice would be greatly appreciated
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Old 04-17-2012, 12:39 AM
ocelot28374 ocelot28374 is offline
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#12, in short yes..
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Old 04-17-2012, 12:49 AM
ocelot28374 ocelot28374 is offline
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Felo, "attach a dc motor with a "upper H" PWM drive as to control not the speed of the motor but PWM control it's breaking action."

Please forgive my ignorance but I dont understand what you are saying.

as for the turbine control it is fairly simple, on my system the controller uses a diversion load in parallel to the batteries when the voltage has exceeded a set point. the turbines in high winds can "over run" the load and continue to provide current to the batteries, over speeding and the burning up in the process. a larger diversion load does provide for more current absorbtion but has the side effect of drastically effecting battery bank voltage and switching between over run and under voltage conditions. damaging the controller and the turbine in the process
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Old 04-17-2012, 12:53 AM
wayneh wayneh is offline
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Quote:
Originally Posted by ocelot28374 View Post
wayneh, Thank you for the search topic. I found a few threads but they seem to deal with shorting the turbine. in high winds this has always resulted in terminal damage to the stator. I am always looking for way to make improvements to my system, any advice would be greatly appreciated
The hard part is the mechanical braking system. The electronic control stuff happens at very low power and voltage. Even the translation of the control signal to higher power to drive a brake is relatively straightforward. But then what?

I know a recent thread on this topic was definitely about a mechanical brake, not electrical. Can't say it will help.
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Old 04-17-2012, 12:53 AM
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Ron H Ron H is offline
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Do your blades have pitch control?
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