VFD Circuit for wood pellet smoker auger feed motor

Discussion in 'The Projects Forum' started by Pellet Smoker, Oct 2, 2015.

  1. Pellet Smoker

    Thread Starter New Member

    Oct 2, 2015
    1
    0
    Looking for a simple design to build a vfd for a single phase 110vac auger feed motor. This auger motor goes on my pellet grill. Pulls roughly 1.5 to 2 amps. Would like to get a max of 70HZ to speed this up when wanted/needed. No design to complicated for me. Any help would be appreciated.

    Thanks,
    Dan
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Can you change the motor to a variable-speed DC motor? Much easier to deal with...
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,554
    2,375
    VFD's for 1ph induction motors do not work well, hence there is not many out there, they tend to drop out of run at low rpm and with load.
    You may be better off looking at a treadmill/DC motor and a simple SCR drive such as KB/Baldor.
    Max.
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,238
    As suggested it's likely easier to change the motor than to build a circuit to vary the line frequency.

    If you still want to do a circuit for that then it would have to deliver about 300W at 110V @ 70Hz.
    One reasonably efficient way is to rectify the line voltage to DC and use that to power a high frequency PWM circuit modulated with a 70Hz sinewave.
    The PWM output circuit would need to generate about a ±160Vpp signal at 3A peak current, which is not a trivial design.
    This PWM signal would be filtered by the motor inductance to give the 70Hz sinewave to the motor.
     
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