igbt gate drive issue

Thread Starter

jbest

Joined Nov 18, 2008
37
Hello i am building an igbt gate drive and i cant seem to get it to work i am using parts that were recommended by some one else as i have no real electronics knowledge to speak of



I am using a 7406 hex inverter ,acnw3130 opto igbt gate drive and igbt g4bc20f

I have attached the pdf for both of them. In the ancw3130 pdf circuit number 29 is the exact circuit i have built except pin 6 of the opto isnt connected and i am running a 2 amp 15 volt supply to it

Any help would be most appreciated thanks james
 

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Thread Starter

jbest

Joined Nov 18, 2008
37
i bypassed the opto and touched the gate directly to the power supply for the opto and the igbt wouldnt turn on i believe the igbt needs more than the power supply and opto can deliver but i dont know how to read the data sheet correctly to confirm this the igbt
 

beenthere

Joined Apr 20, 2004
15,819
If the IGBT gate is more than 10 volts above the source and it's not conducting, it's because the device has failed. The turn on and off rates are dependent on the rate your driver can move charge, but no power is involved with turning the device on and off.

Gate voltage 0 with respect to the source - no conduction. Gate 10 volts above the source - full conduction. Make sure you have correctly identified the gate, source, and drain pins.
 

Thread Starter

jbest

Joined Nov 18, 2008
37
i am using the right pins 1 gate 2 collector 3 emitter

so if i am putting 40 volts into the source pin the i would have to trip the gate with 50 volts

if so i am only putting the 15 volts from the isolated circuit into the igbt and it will never work

do you know where i can find a schematic of circuit with part numbers i can copy

i am wanting to chop up a half wave dc just like a pulse converter dose
i have a 555 square wave circuit up to the 7406 done but the opto isolater and igbt portion is a problem for me and if what i am interpeting from your last post is correct than this is wrong design for me
 

beenthere

Joined Apr 20, 2004
15,819
Can you post up the schematic of the circuit? That way we might be able to make more suggestions as to how to overcome the difficulty.
 

mik3

Joined Feb 4, 2008
4,843
Connect the emitter of the IGBT to ground and connect your load between the collector of the IGBT and the positive of the rectified supply voltage. Also, you need to power the opto with 12 V or more as to be able to turn on the IGBT. What is the part number of the IGBT?
 

nanovate

Joined May 7, 2007
666
if so i am only putting the 15 volts from the isolated circuit into the igbt and it will never work
it will work but the voltage must with respect to the emitter. What is your emitter (pin 3) connected to? Try connecting it to pin 5 of the optocoupler.
 

Thread Starter

jbest

Joined Nov 18, 2008
37
mik the igbt is part number g4bc20f their is a pdf attached to the first post of this thread

nanovate the pin 3 emitter is hooked to the inductive load will it cause damage to the opto isolater if i hook it directly to pin 5 and the inductive load

beenthere i tried hooking the circuit to groung as you said prior to this using an scr and it made the power supply hum like it was causing damage thats what made me move on to this
 
Last edited:

mik3

Joined Feb 4, 2008
4,843
Connect it as I told you in post #10, place the inductor between the collector and the rectified voltage and make sure you have a fast diode across the inductor as to absorb the back EMF when the IGBT switches off. Also, you need to apply more than 10V between the gate and the emitter to turn it on. The maximum gate-emitter voltage is 20V.
 

Thread Starter

jbest

Joined Nov 18, 2008
37
i just tryied as in post 11 and the power is now going thru except it isnt pulsing i remove the trigger wire to the opto and remained on


mik3 i will try it as you said will be back in a moment
 

mik3

Joined Feb 4, 2008
4,843
Post #11 says the same as me because pin 5 of the opto is essentially connected to ground.
Also, connect a 10K resistor between the gate and the emitter as when you remove the signal from the gate the IGBT will turn off. If you don't do it the IGBT will turn off slowly and go into the linear region and you it may get destroyed.
 

Thread Starter

jbest

Joined Nov 18, 2008
37
i dont know whats wrong here their appears to be multiple problems :(
im pretty discoraged ive been messing with this for months on and off

the igbt is turning it self on with nothing attached to the gate the opto isolater isnt doing anything on constant 15.10 volts

all i was trying to do is push a high amplitude wave into the inductor to force it to ring creating a force resonance ringing wave ,transient spike , and a steping up and down pattern that matches the half wave dc it just wont happen for me

:confused:
 

mik3

Joined Feb 4, 2008
4,843
Are you sure you have connected the IGBT with the correct pins?

Did you connect the 10K resistor between gate and emitter? I suspect you connected it between gate and collector.

Check if your oscillator works and if the opto outputs a signal without thr IGBT connected to it. Test the IGBT if it turns on/off when you apply 15V with a wire directly.
 

Thread Starter

jbest

Joined Nov 18, 2008
37
i replaced the opto with a new one im not sure how this opto isolater works i put a scope on the output and it is on constant dose this opto need to have the igbt and resistors attached to turn of

i checked at the input to the opto and has a square wave going to it

and 13.75 constant out of the opto couple and never turns off
i would say thats the first problem i have to fix

the 7406 is feeding directly into the the opto along with a 270 ohm resistor from the 5 vcc i disconected the resistor and measure voltage into the opto and the voltage to opto was.703 just from 7406 with the resistor on the voltage was 1.56 i measured the voltage with resistor hooked to thw vcc was comming out resistor was 4.96
 
Last edited:

mik3

Joined Feb 4, 2008
4,843
The 270 ohm resistor has to be there because the inverter has an open collector output. But why you don't connect the output of the 555 to the input of the opto via a resistor?
What value is the resistor going from the output of the opto to the IGBT?
 
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