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System to brake and lock motor(wind turbine)

Discussion in 'Sensors and Actuators' started by Maru, Nov 3, 2013.

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  1. Maru

    Maru

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    Nov 3, 2013
    Hello,

    I need to come up with a method to brake and stop a wind turbine from turning when a certain wind speed is reached. For the wind turbine generator, I'm using this motor http://uk.rs-online.com/web/p/dc-motors/2985076/ .

    I was considering using regenerative braking but that would not lock the wind turbine. I'm stuck at this point

    The wind turbine is small, about 0.4m x 0.4m x 0.4m

    Background information: I'm designing a braking system for a mini wind turbine. My idea is to connect a low value resistor across the end terminals of the motor to increase current and torque. When not braking, there is a 10 ohm resistor connected across end terminals of the motor by default. I only need a basic idea for a circuit since this project is in early stages.

    http://i.imgur.com/h7HnxCP.png
    Is this something I should be aiming for or is that stupid?

    Also this braking system should be activated once the wind speed reaches a certain speed, If I have a device that measures wind speed how would I create a circuit so that I get the 0.1 ohm resistor between the end terminals of motor instead of 10 ohm resistor automatically

    All help is appreciated.

    With thanks
    Maru
     
    Last edited by a moderator: Nov 21, 2013
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Regenerative braking would not stop the turbine, but it provides a powerful method to limit the RPM (however the turbine could get very hot)

    An alternative approach is to have the tail positioned such that at high speeds the turbine is turned out of the wind. Some designs rotate the turbine into a horizontal position. This only works on relatively small turbines due to the gyroscopic forces that are created.
     
  3. davenn

    davenn Moderator

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    Sep 5, 2009
    Maru

    PLEASE DONT post multiple threads on the same topic

    separate posts have been combined

    Dave
     
  4. Maru

    Maru

    3
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    Nov 3, 2013
    Ok, sorry.

    Can you edit my thread and delete the first part and only include info form my second thread. Thanks
     
  5. davenn

    davenn Moderator

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    Sep 5, 2009
    Note that I had already combined your 2 posts into the one post above :)

    also Note that Steve did respond to you


    Dave
     
  6. Maru

    Maru

    3
    0
    Nov 3, 2013
    I know you combined the two threads, but can you delete the text that was in the first thread. Steve did respond but it does not answer my other question. If you don't understand me can you just please delete this entire thread and I'll remake it.
     
  7. Solidus

    Solidus

    349
    4
    Jun 19, 2011
    Have you looked into the idea of reversing the concept of a centrifugal clutch?

    A centrifugal clutch is the mechanism used on chainsaws - it connects the shaft at a given RPM.

    Essentially, there are spring-loaded pawls or "teeth" on the inner mechanism. At a given RPM, the centrifugal action (note that I didn't say force...er, strict physics) causes the jaws to overcome the load of the spring and engage the outer drum of the clutch.

    By designing a mechanism applying this in reverse (teeth on outer wheel, normally engaged by springs), you'd have a mechanism that would disengage at a set point, determined by the spring tension.

    It wouldn't stop the turbine blade assembly from spinning, but it would allow the motor to spin down and the blades to freewheel. This is much better than trying to load the motor to stop it.
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    My profound apologies for not giving you the perfect answer the first time.

    Sure, I can delete your thread.

    But I'm not going to.

    Just explain a little more clearly what you're trying to achieve.
     
  9. jpanhalt

    jpanhalt

    426
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    Nov 12, 2013
    Why do you want to stop the turbine, rather than just reduce its speed?

    If that is to reduce stress on the tower, then moving the turbine so it is parallel with the wind, as suggested, is probably the best solution for a small unit. On a larger unit, you might consider feathering the blades , i.e., rotating each blade to be parallel with the wind. If you just stop the turbine and leave it facing the wind, the stress on the tower and turbine will remain quite high.

    John
     
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