IGBT Component Testing Question

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  #1  
Old 01-12-16, 05:36 PM
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Question IGBT Component Testing Question

Hello,

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I believe I have here a diagram of what is called an IGBT and I'm trying to determine how to test it to see if it works. I've done some research on testing IGBTs and found that there's a diode test and a capacitance test? I think I've figured out the diode part but still not sure about capacitance. Is the "gate" a capacitor indicated by the two parallel lines?

For diode check, I put the positive (red) probe on pin 2 (emitter) and negative (black) on pin 1 (collector) and I get like 0.3V which I think is correct?

If I reverse the leads I get "OL" which I think is also correct if the diode is working. Correct?

Then, if I measure resistance between pin 3 (gate) and either pins 1 or 2 I get "OL" which means they're not shorted together, correct? I noticed if I put negative (black) on the gate the resistance starts at 0 and climbs until getting "OL" whereas if I reverse the leads I just instantly get "OL". Does it make a difference?

Finally, I'm not sure how to test "capacitance". I keep reading a bunch of stuff saying to short gate and emitter together (pins 2 and 3) and then measure across(?) the collector and emitter (pins 1 and 2) I think? When I do this, and yes my DMM is set to capacitance, I just get a flashing display, no values or "OL".

I read that the DMM needs to have a low voltage supply and that a 9V powered DMM would be fine. Am I supposed to be applying additional voltage from say a 9V battery across the gate and emitter and "shorting" them with a battery? If so, does positive go to the gate? Or am I supposed to be using the DMM and positive on pin 2 and negative on pin 1?

Any help on what I should be doing?

Thanks,
Mike
 
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  #2  
Old 01-12-16, 05:51 PM
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Mike.... testing semis is one of those things we do without thinking. Instead of me typing the best way to do it.... there are some good you tube videos that demo it. Here's one that's really easy to follow. you tube/watch?v=AfV7gYChILc

You should be using the diode/ohm setting on your meter.
 
  #3  
Old 01-12-16, 06:12 PM
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So what's all this junk I'm reading about capacitance and etc.
I've been trying to use these to directions:
1. https://www.galco.com/circuit/igbt_testing.htm
2. http://www.pillartech.com/Portals/0/...-Procedure.pdf

Does this picture change anything on how I would test it?
I think this circuit would turn DC into AC right?

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  #4  
Old 01-12-16, 08:04 PM
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Your picture is of a "two-level converter". Yes, it could, with the correct driver, take DC and make a square wave. More complex variants are used to make 3 phase AC from HVDC transmission lines, and vice-versa.
 
  #5  
Old 01-12-16, 09:11 PM
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Can I test something like this the same way in the video PJmax posted or what would be different?

In this setup I would assume I can test between pins 1 and 3 and 2 and 3 to verify the diode is working by getting 0.3V or "OL" depending on how the DMM probes are connected. I assume I can also test pins 4 and 5 between pins 1, 2, and 3 to determine resistance which I would assume should all be "OL" correct?
 
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Old 01-12-16, 09:25 PM
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I assume I can also test pins 4 and 5 between pins 1, 2, and 3 to determine resistance which I would assume should all be "OL" correct?
That is correct..... OL or no continuity.
 
  #7  
Old 01-13-16, 04:24 AM
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Pete, thanks. I'm not having any luck using the method in the video with my double IGBT. I have the DMM negative on the emitter, pin 3, and positive on the collector at pin 1. I do get OL. But when I touch positive to the gate at pin 4 momentarily and go put positive back on pin 1, I get no change. I would expect that, like in the video, I would get a small voltage?

With positive on 1 and negative on 3 still, if I jump either 1 or 3 to 5, nothing happens either.
 

Last edited by Mike7143; 01-13-16 at 05:41 AM.
  #8  
Old 01-13-16, 12:59 PM
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A multi-meter might tell you if an IGBT is bad, but it can't tell you that it's definitely good. It's been a loooooong time, but here goes:
1. Set your meter for Resistance: Between E and G1 and then G2, both should be open.
2. Set your meter for Diode Check: Jumper E to both G1 and G2.
(I). Between E (+) and C1, you should see the drop across the diode.
(II). Between C1 (+) and E, you should see the drop across the diode.
(III). Between E (+) and C2, you should see an open.
(IV). Between C2 (+) and E, you should see an open.

Think I got it right. Failing any of these tests means its bad. The other tests you can't go with just a meter.
 
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