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  1. #1
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    Does this IGBT bridge meaningless ?

    Hello My Dear Friends!

    Hope this post finds you well.

    I am trying to develop a AC to DC rectifier 110V/50 A range.
    Feeling that I am doing wrong on making the full bridge or half bridge portion.
    The IGBT module I am using is FF75R12RT4,https://www.infineon.com/dgdl/Infine...2805fd8fd76151
    Click image for larger version. 

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    One module contains 2 IGBT that makes me confusing!
    I need to understand my switching topologies first

    Take a look my diagram, how the current flows back from primary winding of TR for a full cycle?

    Click image for larger version. 

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    1. When point A is positive then Q2 conducts, Q1 is OFF?
    2. When point A is negative then Q1 conducts Q2 is OFF?
    3. When point B is positive then Q4 conducts, Q3 is OFF?
    4. When point B is negative then Q3 conducts Q4 is OFF?

    Freewheeling built on doides are available, whats 2uF high voltage is doing here?
    Hasan

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  2. #2
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    Re: Does this IGBT bridge meaningless ?

    It's a regular full bridge, sketched in a rather nondescriptive way. 2uF are DC bus bypass capacitors, strongly suggested to avoid IGBT overvoltage caused by large di/dt.

    1. When point A is positive then Q2 conducts, Q1 is OFF?
    2. When point A is negative then Q1 conducts Q2 is OFF?
    3. When point B is positive then Q4 conducts, Q3 is OFF?
    4. When point B is negative then Q3 conducts Q4 is OFF?
    A is DC+, B is DC- bus node. They don't change polarity. Confusion is apparently caused by the inappropriate schematic style.



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  3. #3
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    Re: Does this IGBT bridge meaningless ?

    Quote Originally Posted by FvM View Post
    It's a regular full bridge, sketched in a rather nondescriptive way. 2uF are DC bus bypass capacitors, strongly suggested to avoid IGBT overvoltage caused by large di/dt.


    A is DC+, B is DC- bus node. They don't change polarity. Confusion is apparently caused by the inappropriate schematic style.
    Question arises if both node remains constant on polarity then why 4 igbts are used? One leg of primary TR connected with a pair of IGBT doesn't tell us that its polarity could interchange? Don't you mean the circuit is not wrong?
    Hasan



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    Re: Does this IGBT bridge meaningless ?

    Hi,

    the circuit seems to be correct.
    Node A is always positive, node B is always negative.

    A "full bridge" needs 4 IGBTs. It has two ouputs. The difference voltage of both these outputs may be positive or negative.

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



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