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Dual axial flux PMG wind turbine

  1. Jun 13, 2014 #1
    I am making a small vertical savonius type wind turbine and would like some general rule guidelines. I am using 14awg magnetic wire--70 turns (2"oval) and ceramic block 1" x 2" x.375" magnets. I am hoping to get the most power possible at lower wind speeds. Is there a rule that states a relationship between wire gauge, turns, magnet strength ie thicker wire,more turns stronger magnets=max power.Also when testing my voltage it spins freely-then test amps and it comes to a screeching halt. is this a problem-if so, how do I fix it?thanks
  2. jcsd
  3. Jun 14, 2014 #2


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    When you measure voltage you are using a high impedance voltmeter that takes almost no energy from the generator. When you measure current you take real energy from the generator and so magnetically brake the generator.

    Ask yourself; why do we not see more Savonius rotors being built and used productively

    A Savonius rotor is the most inefficient rotor available. Unfortunately beginners get fixated on the SR and so can never advance to designs with 10 times the efficiency. The cost of the structural tower needed to handle high winds for a SR is way more than a standard windmill tower where an offset tail can turn the head sideways to reduce damage in strong winds.

    As the devil's advocate I will point out that: An axial flux generator will be less efficient than a traditional design because the magnetic flux path and the length of copper required for the same performance will be greater. Couple that to an inefficient SR, that will stall unless it is duplicated, and you have the engineering equivalent of double jeopardy.
  4. Jun 16, 2014 #3
    Baluncore,thanks for your reply.The reason for the Savonius type rotor is for ease of transportation, size, safety and low wind start up. Basically I am trying to fill a portable power niche for people to charge a battery either in an emergency or for leisure--when off grid.
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