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    inverter single phase with MOSFET

    i will build single phase inverter with MOSFET this is my schema..


    at the first trial, I connect it with 12VDC power sourche with lamp as load..and when I had turned on it, fuse F1 in my schema broken...please help me..
    is my schema wrong?

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    Re: inverter single phase with MOSFET

    your circute looks okay,but what did you use as you oscilator?


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    Re: inverter single phase with MOSFET

    oscilator?
    i use SPWM signal as input optocoupler...i think MOSFET on left side or right side turn on in same time..but in output optocoupler, the signal not turn on in same time...i don know why..


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    •   Alt21st December 2010, 01:35

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    Re: inverter single phase with MOSFET

    I think your problem here is due to cross conduction can you upload your circute diagram.



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    Re: inverter single phase with MOSFET

    this is the signal input opto
    [IMG][/IMG]



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    Re: inverter single phase with MOSFET

    Hi,
    I've had fuses blowing off in H-bridge circuits. The problem wasn't cross-conduction. I think the high-side MOSFETs turn on accidentally. This is explained in Raymond Mack's book "SWITCHING POWER SUPPLIES DEMYSTIFIED". This happens due to a capacitance in the MOSFET that is present between the drain and gate and causes accidental turn-on. Connect a 1k resistor from the gate to source of each MOSFET. This prevents them from accidental turn-on. This was the case many times for me and I had many fuses and MOSFETs blown off.

    Hope this helps.
    Tahmid.
    The blissful feeling of helping others is a unique reward that cannot be gotten from anything else.



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    Re: inverter single phase with MOSFET

    But did you check the signal at the gate of each mosfet before you power it?



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    Re: inverter single phase with MOSFET

    what do you mean Rg=4,7 be replaced with R1K or R1K connected parallel with gate-source MOSFET?

    tihs is signal at the gate each mosfet
    [IMG][/IMG]



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    Re: inverter single phase with MOSFET

    Hi,
    Rg should stay as it is. Connect a 1k resistor between the gate and source in parallel with the MOSFET gate-source ie parallel to the zeners eg D7,D8,D9,D10.

    Hope this helps.
    Tahmid.


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    Re: inverter single phase with MOSFET

    Replace your mosfet and check the gate signal again use your meter to measure the output voltage across j6 and j7 at Ac range and the frequency before connecting your transformer,your diagram and the pwm signal is ok therefore your inverter should work.


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    •   Alt23rd December 2010, 11:59

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    Re: inverter single phase with MOSFET

    yes, i have just Connect a 1k resistor between the gate and source for each MOSFET.and signal Vgs MOSFET for high side and low side are same. and my fuse not blowing off again.

    ---------- Post added at 05:41 ---------- Previous post was at 05:31 ----------

    what is the output SPWM inverter need filter?and how to calculate L and C?the output for inverter have variabel frecuency..



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    Re: inverter single phase with MOSFET

    What is your voltage between j6andj7 at AC range? and to calculate the value of your LC then use the resonance frequency formula, you can follow this link for more info. en.m.wikipedia.org/wiki/LC_circuit



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    Re: inverter single phase with MOSFET

    AC range is 110-220V
    hufh...,my board error again...i think connection ground IR2112 and DC- have any problem..i dont know after i turn on my DC source, and my board blow up...IR2112 was broken again..



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    Re: inverter single phase with MOSFET

    Did you have that 1k resistor from gate to source?



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    Re: inverter single phase with MOSFET

    yes, i have conected 1K resistor...what is the ground between IR 2112 and DC- need resistor too?or V supply to Dioda and capasitor bootstrap need resistor too?



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    Re: inverter single phase with MOSFET

    No,
    Everything else looks alright. The capacitors between pins 3 and 2 and the capacitor between pins 5 and 6 should be of the same value. Have you checked to see if the MOSFETs are okay or shorted? Check that, maybe you have shorted MOSFETs.

    Hope this helps.
    Tahmid.



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    Re: inverter single phase with MOSFET

    The capacitors between pins 3 and 2 and the capacitor between pins 5 and 6 are not same in my schema.The capacitors pins 3 and 2 is 2,2 uF and The capacitors pins 5 and 6 is 470nF. yes, i will check the MOSFETs



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    Re: inverter single phase with MOSFET

    Quote Originally Posted by bobbywu View Post
    The capacitors between pins 3 and 2 and the capacitor between pins 5 and 6 are not same in my schema.The capacitors pins 3 and 2 is 2,2 uF and The capacitors pins 5 and 6 is 470nF. yes, i will check the MOSFETs
    Yes, I've seen that. I don't think it will cause much problems but I've read somewhere that you should use capacitors of same value.

    Hope this helps.
    Tahmid.



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    Re: inverter single phase with MOSFET

    Hi, the capacitors value are not the problem,before you power the inverter you have to cheak the output between j6 andj7, view it with osciloscope if posible you will see if the output signal is okey before you connect your transformer,also cheak the Vgs of High side and the low side how many volt did you see?



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    Re: inverter single phase with MOSFET

    i have tested the circuit.Vgs of High side and the low side are same.and but if i connect it with DC source, lane between DC-(and wil go to the pin COM)and ground V supply for IR2112 blow up.in several literature books,DC power before go in inverter circuits will be split with two capasitors to get 0voltage in the midlle from two capasitors.what does this mean? iwhat the effect if i not use capasitors?thanks



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