trying to find IGBT gate resistor value (not internal)

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BGAmodzX

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Hello everybody here.

I have a switch mode unit working with two IGBTs each one of them got its gate connected to a resistor witch was burned , and am trying to find its value .

I have checked some other units basically small welders using IGBTS and i find values ranging from 3 ohms to 33 ohms.

This is the name of the IGBTs NGTB50N60FLWG
 

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The gate is essentially a 1.5nF capacitor according to the datasheet. What voutage and frequency are you running on the gates? And yes, 10ohms is pretty typical (3.3 to 33). Don't use a wire-wound resistor for this application!
 
gophert said:
The gate is essentially a 1.5nF capacitor according to the datasheet. What voutage and frequency are you running on the gates? And yes, 10ohms is pretty typical (3.3 to 33). Don't use a wire-wound resistor for this application!
Click to expand...
Am sure there is some formula out there but i am lacking gate voltage and maybe some other stuff.
but anyways i have some resistors to try and a potentiometer . once i get some oscillator signal from the gate using my oscilloscope , we will try to make sure its a safe signal for driving the IGBTs.
 
A ‘witch was burned’ may have been a common statement in Medieval times.
 
BGAmodzX said:
Lolz

In my case a resistor was fried to death and we dont know what to do about it
Click to expand...

If the resistor is the only connection to the gate (no additional components meandering into the junction), I would just add a 1 to 3.3 ohm resistor and see what happens. Either it will fail or it won't. If it doesn't, touch it to see if it is getting hot. If it is too hot to touch, put a higher wattage and try again. Then check if you have any interference with any TVs, cell phones or ... if not, your done.
 
Is it only the resistor that was burned at stake, or did the igbt suffer as well? My experience is that usually the power element dies first and takes the gate resistor and possobly gate driver along for the ride.
 
kubeek said:
Is it only the resistor that was burned at stake, or did the igbt suffer as well? My experience is that usually the power element dies first and takes the gate resistor and possobly gate driver along for the ride.
Click to expand...
Yes the igbts were shorted .

I also found out thay a small auxiliary power supply was down , found too many shorted components , i need to get this aux power supply running again before trying to check igbt signal with my oscilloscope.

I will try to upload some pictures
 
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