Does this IGBT bridge meaningless ?

Thread Starter


Joined Sep 5, 2019
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,

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?


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?


Joined Jul 11, 2016
? are you overthinking (the point A is unlikely neg. . . . ) -- the upper fig. (a half bridge with K sources) is ok
-- the lower one however is configured mistily (i don't want to dig into this (not my area of comfort))
but either you need to swap lower transistors . . . or other that allows you to set AC/SqWv to T2
the input polarity
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