Three phase Triac Control

Discussion in 'General Electronics Chat' started by thalesmaia, May 1, 2015.

  1. thalesmaia

    Thread Starter New Member

    May 1, 2015
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    Hello, first topic seeking for help. Sorry about my english...

    I build a three phase oven heater using triac and an arduino.

    During low load operation it works very good (60W bulb lamp), but when I change the load (8.5kW heater) is has a strange firing problem.

    I attached the circuit in LTSpice for more detailed explanation, but when I trigger Vbc phase I get conduction on Vab phase as well.

    The first problem is that LTSpice simulation does not converge, trying to figure it.
    Second that I have no clue what may be...

    Any help are welcome.

    https://drive.google.com/file/d/0BwVP4AzXV_MqWkdXc2UybTJ3MG8/view?usp=sharing
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Is the supply 3ph and neutral, with a element bank on each phase to neutral?
    Or how is the supply configured, is it Star or Delta supply?
    Are you phase angle controlling it or burst firing, full on/off?
    Max.
     
  3. thalesmaia

    Thread Starter New Member

    May 1, 2015
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    Hi Max, thanks for the fast answer.
    It is Delta and I'm controlling the angle as well.

    Please check the attached drawing for better understanding.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    With heating/element loads it is more common to use burst firing, not so electrically noisy and usually the same feedback is used.
    Have you considered this?
    Max.
     
  5. thalesmaia

    Thread Starter New Member

    May 1, 2015
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    It is also a good approach, I can work the way proposed. Thank you.

    In the other hand, I must understand the problem in my design, and still want to find the answer.
    Any suggestions?
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Do you mean you see see phase angle control on AB phase at the same time?
    Does it follow the change (in step) when BC phase angle is changed?
    Max.
     
  7. thalesmaia

    Thread Starter New Member

    May 1, 2015
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    Exactly! When I trigger BC phase, the AB phase conduct, even with trigger gate pin disconnected.

    The same happen for the other phases:
    Fire CA also trigger BC
    Fire AB also trigger CA

    All in that other. I added a snubber but is still the same.
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Is the circuit you show in #3 exactly the way it is configured? Could you not do it with 3 Tracs?
    Max.
     
  9. thalesmaia

    Thread Starter New Member

    May 1, 2015
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    I just need to find a 60A triac.
    Any suggestion?
    This was a cheap solution...
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You most likely will find SCR's that not only go much higher current than Triacs, but are a lot cheaper, two back to back for each phase.
    Max.
     
  11. Reloadron

    Active Member

    Jan 15, 2015
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