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Reverse current flow through an IGBT

For applications like high voltage three phase PWM inverters when the high and low FETS are complementary to each other, the effect is similar to a synchronous rectifier circuit. When the top FET turns off and the bottom FET turns on, the freewheeling current flows backwards through the bottom fet. With Mosfets, the channel will allow current to flow in either direction and the Mosfet shorts out its antiparallel diode Vf for increased efficiency.

With an IGBT, is that also the case that the biased ON IGBT will short out the diode Vf and reduce the voltage across the C-E pins in this condition?

Reply to
Mook Johnson
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out

condition?

I don't think so.

They make IGBTs with integral reverse diodes for this purpose.

Tim

-- Deep Fryer: A very philosophical monk. Website @

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Reply to
Tim Williams

Yup, appears so. From what I've read there is the equivilent of a forward biased diode in series with the collector pin. The antiparallel diode goes around this so the reverse current voltage drop is entirely dependant on the voltage drop of the antiparallel diode.

I'm looking at ways to reduce this voltage. Looks putting a better antiparellel doide in parallel is the only way.

thanks Tim

Reply to
Mook Johnson

The entire advantage to IGBTs is their low Vce(sat), which is only a few diode drops typical. This is of no advantage to lower voltages (under

100-200V, say), where MOSFETs of comparable ratings have Rds(on) giving lower voltage drop for the same load currents.

So, what I'm saying is, why are you interested in an IGBT when you seem to be looking for a MOSFET?

What specs are you looking for in saturation voltage, current, peak voltage capacity, rise/fall time, etc.?

Tim

-- Deep Fryer: A very philosophical monk. Website @

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Reply to
Tim Williams

Nobody does it this way in practice, N channel devices are almost allways used.

the effect is similar to a

bottom

er

d

There are NO P channel igbt's.

Reply to
cbarn24050

Toshiba GT20D201, for one.

-250V, 20A

-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)

Reply to
Fred Abse

Sure there are. At least, I recall seeing some listed in an older issue of Mouser's catalog. Hmm, don't see any at the usual suspects.

Certainly, not many people _use_ them.

Tim

-- Deep Fryer: A very philosophical monk. Website @

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Reply to
Tim Williams

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