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  1. #1
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    mosfet bridge rectifier

    Hi all,

    i would like to ask about the possibility of rectification of AC input using Mosfets instead of diodes....

    is that possible that by replacing all 4 diodes with 4 N-Mos for rectification with proper gate control circuit?

    The reason of using Mosfets rather than diodes is to reduce the loss on the rectification circuitry....

    Can anyone help me?

    Thanks,
    kit

    •   Alt27th May 2009, 05:04

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    mosfet rectifier

    This is what you want, everything expalined in it. I think it helps you.

    ENJOY!


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  3. #3
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    using mosfets

    Basically possible, but needing a rather complex driver circuit with an auxilary supply or bootstrap. The equivalent circuit is a H-bridge.



    •   Alt27th May 2009, 05:56

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    full wave rectifier

    In itself its not much of a problem ,i builded this before aswell discrete (transistors),with comperators as with IRF chipsets .
    Elektor published a schema a few years ago but i didnt like it cause it used 2 p-mosfets (adding dissapation).
    (Power MOSFET Bridge Rectifier-Published in issue 356, July 2006)
    (little edit the elektor schema i mentioned is the one you posted (i dont like that one)
    Most simple solution is get some IR1166 of 1167 and build what they present in this paper .
    http://www.irf.com/technical-info/wh.../TP-080527.pdf
    When you have a look at the signals in this paper its clear you can easily do this with simple comperators like lm393 + gatedrivers or even BC transistors building emmiter coupled schmitt triggers .
    (i tryed all these versions and the difference in efficiency is neglectable)
    Personaly i prefer the comperator version for low partcount and ease of getting components .
    Take a transformer with middletap ,this way you can use 2 nmos and take the gatevoltage + supplyvoltage for the comperators etc. from the middletap .
    My prototypes managed 30 Amperes at a loss of 1,2 Watt's in the mosfets (0,58 in every mosfet .
    Its definetly the way to go for big amperes at low loss .

    Good luck :)


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    mosfet rectifier circuit

    Hi,
    Using Mosfets as rectifier is not a difficult job but I find it logical to use for bigger Ampheres like>30A.



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    mosfet full wave rectifier

    Doing this for low power applications is not really usefull .
    The cost of components and the space needed for them makes it much more usefull for higher current applications .
    For just a few Amperes ,you could choose the *ideal diodes* from linear .
    But they are just up to 5 Ampere .
    For bigger currents you can design your own or use the IRF chipset where you can go as bad as you like or need .
    (limited by 7A gatedrive capability)



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    full wave rectifier using mosfet

    Quote Originally Posted by walkura
    Take a transformer with middletap ,this way you can use 2 nmos and take the gatevoltage + supplyvoltage for the comperators etc. from the middletap .
    My prototypes managed 30 Amperes at a loss of 1,2 Watt's in the mosfets (0,58 in every mosfet .
    Its definetly the way to go for big amperes at low loss .

    Good luck :)
    If you want to go for big amperes and low loss, you want also use all the copper you have in your transformer as much as possible, so a middletap transformer is maybe not so good solution.

    stefaan



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    full wave bridge rectifier by using mosfet

    Concerning the middletap .
    You can choose this option to lower your partcount .
    In itself its no problem to build a Graetzbridge with 4 mosfets ,but it is more then twice the amount of parts .
    For me here in Poland ,using a middletap transformer is a cheaper option then adding 2 extra IR1167 + mosfets .
    My reason for using that setup is strictly a economical + ease of production .



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