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Please confirm IGBT only conducts in one direction

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The title page tells "IGBT and diode"
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There are a few small IGBTs without diode (in e.g. TO-247 package) on the market, but no power module. Reason is that IGBT has low (e.g. a few 10 V) reverse breakdown voltage and must be protected by an antiparallel diode anyway.

Difference to MOSFET is that you see diode voltage drop and reverse recovery losses associated with reversed current direction. Voltage drop of high voltage MOSFET at rated current can be lower, but not much.
 
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thanks, sorry, i am not referring to the diode, i am referring to the CE channel. Please confirm no current can go from E to C? (lets pretend the pllel diode isnt there)
Effectively, we could say there is like effectively a diode from C to E, with cathode to E? (and this diode comes on when Gate is pulsed high......is that plausable explanation? (i know its not accurate from a semi phys point of view)
 

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nah mate, take the diode away and the Vec break down is typically 6-7V, put loads of current thru in this direction and you'll bugger it.
 
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You should know well that IGBT are not actively reverse conducting, any power electronics designer knows. But whats the problem behind your question?
 
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Hi,

The diode does exist. So it does conduct in reverse.
So where do you see the difference between "pure IGBT reverse conduction" and "diode reverse conduction".

From the electrical view I see no difference.

Klaus
 
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But whats the problem behind your question?
Click to expand...
Difficult to give detail without violating NDA....but basically, if an IGBT is gated ON, but V(e) > V(c), then absolutely no current will flow from e to c?...it will *all* go through the anti-parallel diode?
 

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Thanks, theres no IGBTs in LTspice so i guess i will have to use a NFET and put a series diode with it.
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Hi,
We all know IGBTs have tail current, as the channel stays conducting for some 500ns after the gate voltage goes to zero...but where in the datasheet of the top post does it give the "tail time"?...ie, that time that the channel stays condcuting after gate voltage has fallen to zero?.......i dont believe its in the datasheet?....ive looked thru and thru.
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Also, if your "off" gate drive goes negative...say to -5V, then does that reduce the "tail time"?
 
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correct, tail times are not given these days as they are generally small and less than 200nS, depending on the part, you can buy reverse blocking IGBT, but they are rare.
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neg gate has very little effect on tail.
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thanks, is the point of neg gate drive with IGBTs to stop spurious gate turn on?
Thanks for the rev block IGBT... i will check the sim and see what rev volts we have on e-c. If its too high then i guess we need rev blocking..

ive just realised the igbt in the top post doesnt give V(ec) max. Wonder why not?
 

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Yes. It's somewhat strange to see an IGBT referred to that way, since "reverse conducting" is the norm.

In principle, yes, if you take away the antiparallel diode, IGBTs can block reverse current to some extent. Some vendors do offer IGBTs without the antiparallel diode. In theory these are fine to use in circuits like boost converters where the IGBT should never need to operate in quadrant 3 (like a boost converter). Interestingly, these devices never seem to specify their behavior in quadrant 3, suggesting that they're intended to be used with an external antiparallel diode.

While reading about this, I came across some info about devices that are actually intended for reverse-blocking. Not sure if they're even obtainable anymore.
 
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