single phase inverter using scr

Discussion in 'General Electronics Chat' started by Tinsae, Jan 10, 2015.

  1. Tinsae

    Thread Starter New Member

    Jan 8, 2015
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    Hi guys i am new to forum. I need to build
    Single phase inverter using four scr, diodes and a capacitor as like h bridge. But i am not sure the spec of capacitor for 3kw motor. I have attached picture
     
  2. tcmtech

    Well-Known Member

    Nov 4, 2013
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    No picture and far more info is needed. :(
     
  3. Tinsae

    Thread Starter New Member

    Jan 8, 2015
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    Thankyou. I have tried to attach a picture. I will try again with further explanation
     
  4. Tinsae

    Thread Starter New Member

    Jan 8, 2015
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    Hi guys. I tried to attach a picture. To clarify my question what i need is building inverter for 3kw single phase motor using thyristor. I cant use igbt coz i couldnt get them in my country. So i want to use 4 thyristor for H-bridge type since thyristor canot be stopped via get i have seen a technique of forcing them using capacitor as shown in the figure so my question is how to select such capacitor
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    What type of 1ph motor, that is quite large for a 1ph motor?
    Thyristor are a bad choice for induction motor especially 1ph, which are prone to drop out of run, even when IGBT drives are used.
    Max.
     
  6. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,037
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    Yes an H bridge inverter can be made with SCR's to drive an induction load but it s not an easy or cheap device to make plus given your motor is ~3000 watts the odds are its typical capacitor start type which in itself by design are very limited on what speed above or below its standard rated RPM's it can work at.

    If you need a to have a wide speed and power range you would be time and money ahead to buy a 3 KW three phase motor and run that with a properly sized Variable Frequency Drive.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    This is why many of the CNC hobiest convert to 3ph motor and use a VFD with 1ph supply for induction motor control, you will seldom see any 1ph motor and VFD users among these.
    Max.
     
  8. Tinsae

    Thread Starter New Member

    Jan 8, 2015
    15
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    Thankyou all very much.
    Answering your question...
    The type of motor is 3kw single phase capacitor start motor.

    Yes thyristor is big for 3kw range but z problem is in my country Ethiopia you couldnt get igbt igbt driver and others easily what i found on scrap market is only thyristor that is why i plan to use scr.
    I understand from u that capacitor run single phase motor control is difficult there i will plan to use 3phase motor
     
  9. Tinsae

    Thread Starter New Member

    Jan 8, 2015
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