Help me to convert single phase AC in to Three phase AC Voltage

Discussion in 'The Projects Forum' started by g_shyam1682, Jan 25, 2010.

  1. g_shyam1682

    Thread Starter New Member

    Jan 25, 2010
    hello friend

    Currently, in my project, i am using VFD drive to convert single phase in to three phase AC Voltage

    But, VFD(AC Drive) is costly for my project
    So, i want to build a Circuit to convert them
    and i want to build that myself

    so any one has some idea, please tell me and help me
  2. BillB3857

    AAC Fanatic!

    Feb 28, 2009
    Have you opened the VFD you have to see the complexity involved? If you do, you will probably change your mind. Just my opinion.
  3. 3ldon

    Active Member

    Jan 9, 2010
    VFD's are on ebay for 10 cents a watt. It is impossible to beat that building it yourself.
  4. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    If you are only running a small motor with low starting torque, you can cheat...

    Configure the motor so it's set for the same voltage as your single phase supply (or use a transformer to provide an appropriate single phase voltage).

    Connect the supply across two phases and a motor run capacitor from one supply phase to the third motor phase. Which supply phase you use will control the direction.

    The capacitor value depends on the motor ratings.

    In effect, you are making it in to a 'capacitor run' motor.

    You won't get the full torque you would with a true three phase supply, but it's fine for many applications.
  5. davlok

    New Member

    Oct 28, 2009
    I have a 5HP three phase 240 volt motor that i bring up to rpm with a small 110v motor coupled to the shaft, it is on a momentary switch. When it is up to rpm I switch 220volts into one leg and shut down the starter motor. and just hook up my Milling machine motor up to this (pony)motor,phase to phase and it has been working fine for the last 15 years. Your pony motor has to match rpm's as your machine motor and the pony motor has to be the same or larger for this to work.
    I here guys putting capcitors in and other things. I just use the pony motor and a three phase contactor to put power into one leg and basicly tun it into a 3 phase alternator. I can go from full power one direction to stop and full power the other direction with no problems. This system has been used for years by home machinests