DIR Return Create A Forum - Home
       ---------------------------------------------------------
       Lynx Wind Forum
  HTML https://lynxwindforumhtml.createaforum.com
       ---------------------------------------------------------
       *****************************************************
   DIR Return to: Electronics related to alternative Energy
       *****************************************************
       #Post#: 593--------------------------------------------------
       Alternator Basics
       By: lynx wind Date: October 16, 2013, 4:26 pm
       ---------------------------------------------------------
       I thought this might be helpful.  It's so hard to glean through
       all the information out there.
       What variables affect voltage:
       1.  Number of poles (magnets and coils)
       2.  Number of turns on a coil of wire
       3.  RPM or cycles per minute (flux change/time)
       4.  Assume magnet to coil gap is a constant, magnet size is a
       constant
       double the number of poles = 4 fold increase in voltage
       double the number of turns = 2 fold increase in voltage
       double the rpm or cycles     = 2 fold increase in voltage
       The cheapest way to increase voltage is to increase rpm.  Given
       there is enough space, increasing the number of turns is the
       next best.  Increasing the number of poles is the very best but
       usually requires a re-design and more $$$.
       #Post#: 594--------------------------------------------------
       Re: Alternator Basics
       By: burnit0017 Date: October 16, 2013, 5:57 pm
       ---------------------------------------------------------
       Hi, how about the internal stator resistance? The higher the
       resistance the higher the (I squared R) loss and that creates
       heat and drag at the stator.
       #Post#: 596--------------------------------------------------
       Re: Alternator Basics
       By: lynx wind Date: October 16, 2013, 8:46 pm
       ---------------------------------------------------------
       Yes, that's right.  A designer could use a 1000 turns of 30awg
       to get very high voltage, but the wire will only pass an amp of
       current before the wire gets so hot it melts.  So for a 12 volt
       battery that would be 12 watts max.
       The larger the diameter of wire the more current can pass
       through without it becoming excessive heat.  With careful design
       a compromise can be found that gives the best power to a certain
       load.
       I do this with spreadsheets that have all the design
       considerations as inputs.
       Magnet size, number of poles, distance between magnet and coil,
       flux, coil dimensions and turns, number of poles, gauge wire,
       and rpm range.  The spreadsheet outputs total resistance,
       voltage at rpm, watts lost in the coils, watts to the load.
       Then I readjust the inputs to align the best efficiency for the
       expected rpm range.  It is difficult to predict rpm under load
       and I have found the best way is to experiment and learn the rpm
       range for the particular machine.  After awhile it gets easier
       to predict fairly close and then adjust the alt specs.
       *****************************************************