# Calculate switching frequency for IGBTs

Discussion in 'General Electronics Chat' started by Varkatzas, Nov 8, 2012.

1. ### Varkatzas Thread Starter New Member

Oct 22, 2012
15
0
Hi,

Is it possible to calculate the max frequency at which an IGBT can operate by the information in the Datasheet?

I'm guessing that is not only by the turn-on and turn-off times, but it has to be with some of charge or current (because the 'tail current') information.

Thanks

2. ### tshuck Well-Known Member

Oct 18, 2012
3,531
675
this information should be in the datasheet... what device are you using?

3. ### Varkatzas Thread Starter New Member

Oct 22, 2012
15
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i'm using a Fuji -- 2MBI200U4B-120 but in the datasheet says nothing concrete about the switching frequency. Thanks

4. ### tshuck Well-Known Member

Oct 18, 2012
3,531
675
Provided you are using the test conditions(which, you probably aren't), you could calculate it based on the switching times.

Since you probably aren't, you'd need to do some experiments...

5. ### Varkatzas Thread Starter New Member

Oct 22, 2012
15
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Since i can't buy the module until it's well justified "why this module", i'm basing in the information in the datasheet.

The problem with the switching time information is that it only tells us the time of RISE and FALL; in other datasheets, this info is given along with the frequency of operation and it doesn't match. Because of that, i´m assuming that more information needs to be considered.

6. ### tshuck Well-Known Member

Oct 18, 2012
3,531
675
What voltages/currents are you trying to control? Another FET may be better suited to your cause...

7. ### Varkatzas Thread Starter New Member

Oct 22, 2012
15
0
It's a DC DC converter of 7.5kW: 750V and 10A on one side and 18.7v and 40A on the other side. There are not many MOSFETs which hold out for these parameters.

8. ### crutschow Expert

Mar 14, 2008
13,477
3,362
If you drive the gate with a sufficiently low impedance driver, the you can estimate the frequency based upon the rise and fall times. Generally you would want the sum of those two times to be no more than perhaps 10% of the waveform total period for good converter efficiency since the transistor dissipates significant energy during the switching time.