Have my bus caps died?
nzoomed, Sat Nov 05 2016, 09:41PMI had my tesla coil running at my mates place last night, and after a very short time, the power output dropped off significantly not long after turning up the bus voltage to full.
I think i saw a very tiny amount of smoke come from the inverter unit, but i was expecting the caps to explode or spray out electrolyte everywhere if it was a catastrophic failure?
It popped the circuit breaker shortly afterwards in the house, and it pops it every time i plug it into the wall.
I got home late and dont have much time to check it right now, but this is what i expect has failed.
If the IGBT's had failed, should i expect to see some visible signs and/or smell?
I had always been unsure of the ripple / current rating of my caps anyway as i can not find a datasheet, and intended to upgrade them anyway.
I have been looking at these, and i think they are the same ones that Loneoceans is using on his newer coils.
Re: Have my bus caps died?
Inducktion, Sat Nov 05 2016, 10:27PM
Not every time electronics fail catastrophically. I've had times where mosfets and IGBT's failed quite quietly, which made diagnosing the issue so much more difficult. I'd definitely try checking out your switches first, to make sure that they haven't failed. It's very likely they were actually what broke and not your caps.
Inducktion, Sat Nov 05 2016, 10:27PM
Not every time electronics fail catastrophically. I've had times where mosfets and IGBT's failed quite quietly, which made diagnosing the issue so much more difficult. I'd definitely try checking out your switches first, to make sure that they haven't failed. It's very likely they were actually what broke and not your caps.
Re: Have my bus caps died?
nzoomed, Sat Nov 05 2016, 11:22PM
I dont have any switches that could have failed, but im going to have to pull the whole inverter apart now to isolate the IGBT's from the bus and test for any internal shorts on the caps.
Hopefully the IGBT's are OK, as the caps are much cheaper to replace.
nzoomed, Sat Nov 05 2016, 11:22PM
Inducktion wrote ...
Not every time electronics fail catastrophically. I've had times where mosfets and IGBT's failed quite quietly, which made diagnosing the issue so much more difficult. I'd definitely try checking out your switches first, to make sure that they haven't failed. It's very likely they were actually what broke and not your caps.
Not every time electronics fail catastrophically. I've had times where mosfets and IGBT's failed quite quietly, which made diagnosing the issue so much more difficult. I'd definitely try checking out your switches first, to make sure that they haven't failed. It's very likely they were actually what broke and not your caps.
I dont have any switches that could have failed, but im going to have to pull the whole inverter apart now to isolate the IGBT's from the bus and test for any internal shorts on the caps.
Hopefully the IGBT's are OK, as the caps are much cheaper to replace.
Re: Have my bus caps died?
Polonium210, Sun Nov 06 2016, 05:42PM
By switches I think he is referring to your IGBT's as switching devices..
Polonium210, Sun Nov 06 2016, 05:42PM
nzoomed wrote ...
I dont have any switches that could have failed, but im going to have to pull the whole inverter apart now to isolate the IGBT's from the bus and test for any internal shorts on the caps.
Hopefully the IGBT's are OK, as the caps are much cheaper to replace.
I dont have any switches that could have failed, but im going to have to pull the whole inverter apart now to isolate the IGBT's from the bus and test for any internal shorts on the caps.
Hopefully the IGBT's are OK, as the caps are much cheaper to replace.
By switches I think he is referring to your IGBT's as switching devices..
Re: Have my bus caps died?
nzoomed, Sun Nov 06 2016, 09:19PM
OK, very true, i was half asleep when posting lo.
Hopefully they are OK, but any idea if that would cause a short when connecting to mains?
I also dont know why my CM300's should fail like that after such short operation?
My OCD was set to only 750A and these can handle far more than that.
Only thing is perhaps the phase lead driver has an issue?
nzoomed, Sun Nov 06 2016, 09:19PM
Polonium210 wrote ...
By switches I think he is referring to your IGBT's as switching devices..
nzoomed wrote ...
I dont have any switches that could have failed, but im going to have to pull the whole inverter apart now to isolate the IGBT's from the bus and test for any internal shorts on the caps.
Hopefully the IGBT's are OK, as the caps are much cheaper to replace.
I dont have any switches that could have failed, but im going to have to pull the whole inverter apart now to isolate the IGBT's from the bus and test for any internal shorts on the caps.
Hopefully the IGBT's are OK, as the caps are much cheaper to replace.
By switches I think he is referring to your IGBT's as switching devices..
OK, very true, i was half asleep when posting lo.
Hopefully they are OK, but any idea if that would cause a short when connecting to mains?
I also dont know why my CM300's should fail like that after such short operation?
My OCD was set to only 750A and these can handle far more than that.
Only thing is perhaps the phase lead driver has an issue?
Re: Have my bus caps died?
Inducktion, Sun Nov 06 2016, 09:30PM
Honestly taking apart the inverter and testing the parts would likely be the safest option anyway, to make sure nothing else failed. Typically when one thing goes, it has a tendency to take other stuff with it so it's always a good idea to double check everything.
And yeah, when i said switches I meant your IGBT's, sorry. Should've clarified :P
Any number of different things could have caused your CM300's to die. Excessive current isn't the only killer; too much gate voltage, resonance, too much voltage period, oscillations, etc, can all very easily kill silicon.
Inducktion, Sun Nov 06 2016, 09:30PM
Honestly taking apart the inverter and testing the parts would likely be the safest option anyway, to make sure nothing else failed. Typically when one thing goes, it has a tendency to take other stuff with it so it's always a good idea to double check everything.
And yeah, when i said switches I meant your IGBT's, sorry. Should've clarified :P
Any number of different things could have caused your CM300's to die. Excessive current isn't the only killer; too much gate voltage, resonance, too much voltage period, oscillations, etc, can all very easily kill silicon.
Re: Have my bus caps died?
nzoomed, Mon Nov 07 2016, 06:00AM
They are supposed to take this OK.
My coil is running at a fairly low frequency also (under 60KHz)
If my IGBT's have fried, i have no idea where to go, as i dont really want to see another $300 go up in smoke! :(
Hopefully ill have time to look at it tomorrow.
If im lucky it may be something simple like the rectifier.
nzoomed, Mon Nov 07 2016, 06:00AM
Inducktion wrote ...
Honestly taking apart the inverter and testing the parts would likely be the safest option anyway, to make sure nothing else failed. Typically when one thing goes, it has a tendency to take other stuff with it so it's always a good idea to double check everything.
And yeah, when i said switches I meant your IGBT's, sorry. Should've clarified :P
Any number of different things could have caused your CM300's to die. Excessive current isn't the only killer; too much gate voltage, resonance, too much voltage period, oscillations, etc, can all very easily kill silicon.
Ive been using the UD 2.7 to drive the inverter at 24v on the gates.Honestly taking apart the inverter and testing the parts would likely be the safest option anyway, to make sure nothing else failed. Typically when one thing goes, it has a tendency to take other stuff with it so it's always a good idea to double check everything.
And yeah, when i said switches I meant your IGBT's, sorry. Should've clarified :P
Any number of different things could have caused your CM300's to die. Excessive current isn't the only killer; too much gate voltage, resonance, too much voltage period, oscillations, etc, can all very easily kill silicon.
They are supposed to take this OK.
My coil is running at a fairly low frequency also (under 60KHz)
If my IGBT's have fried, i have no idea where to go, as i dont really want to see another $300 go up in smoke! :(
Hopefully ill have time to look at it tomorrow.
If im lucky it may be something simple like the rectifier.
Re: Have my bus caps died?
Hydron, Tue Nov 08 2016, 11:15AM
If it's the IGBTs that have gone, you should be able to replace them for significantly less than $300, even if you have to get something off US ebay freight-forwarded to NZ
Hydron, Tue Nov 08 2016, 11:15AM
If it's the IGBTs that have gone, you should be able to replace them for significantly less than $300, even if you have to get something off US ebay freight-forwarded to NZ
Re: Have my bus caps died?
nzoomed, Tue Nov 08 2016, 11:37PM
It cost me at least $300 (NZD) for my last pair of IGBT's, plus shipping, and that was with a better exchange rate than today.
But i see other suppliers have them a little cheaper for just under $100 USD each, that would still cost me about $300 (NZD) for a pair landed here.
I have not pulled it apart yet, but as i speak, ive put my multimeter across the DC bus and it measures around 100 ohms, not sure what this should normally read, but its not a dead short.
nzoomed, Tue Nov 08 2016, 11:37PM
Hydron wrote ...
If it's the IGBTs that have gone, you should be able to replace them for significantly less than $300, even if you have to get something off US ebay freight-forwarded to NZ
Sorry, that is New Zealand dollars, im referring to.If it's the IGBTs that have gone, you should be able to replace them for significantly less than $300, even if you have to get something off US ebay freight-forwarded to NZ
It cost me at least $300 (NZD) for my last pair of IGBT's, plus shipping, and that was with a better exchange rate than today.
But i see other suppliers have them a little cheaper for just under $100 USD each, that would still cost me about $300 (NZD) for a pair landed here.
I have not pulled it apart yet, but as i speak, ive put my multimeter across the DC bus and it measures around 100 ohms, not sure what this should normally read, but its not a dead short.
Re: Have my bus caps died?
hen918, Wed Nov 09 2016, 11:38AM
If there was a dead short something would have made a really big bang! When they fail quietly they don't tend to go to 0 ohms. IGBTs should read many orders of magnitude higher than that, normally.
hen918, Wed Nov 09 2016, 11:38AM
nzoomed wrote ...
....
I have not pulled it apart yet, but as i speak, ive put my multimeter across the DC bus and it measures around 100 ohms, not sure what this should normally read, but its not a dead short.
....
I have not pulled it apart yet, but as i speak, ive put my multimeter across the DC bus and it measures around 100 ohms, not sure what this should normally read, but its not a dead short.
If there was a dead short something would have made a really big bang! When they fail quietly they don't tend to go to 0 ohms. IGBTs should read many orders of magnitude higher than that, normally.
Re: Have my bus caps died?
nzoomed, Wed Nov 09 2016, 08:08PM
OK, I have removed the caps from the DC bus, and the resistance on the IGBT's is off the scale on my multimeter on one of them, and the other is way up in the megohms range.
Seems it must be the caps, but im going to need to test these on a proper PSU now...
nzoomed, Wed Nov 09 2016, 08:08PM
hen918 wrote ...
If there was a dead short something would have made a really big bang! When they fail quietly they don't tend to go to 0 ohms. IGBTs should read many orders of magnitude higher than that, normally.
nzoomed wrote ...
....
I have not pulled it apart yet, but as i speak, ive put my multimeter across the DC bus and it measures around 100 ohms, not sure what this should normally read, but its not a dead short.
....
I have not pulled it apart yet, but as i speak, ive put my multimeter across the DC bus and it measures around 100 ohms, not sure what this should normally read, but its not a dead short.
If there was a dead short something would have made a really big bang! When they fail quietly they don't tend to go to 0 ohms. IGBTs should read many orders of magnitude higher than that, normally.
OK, I have removed the caps from the DC bus, and the resistance on the IGBT's is off the scale on my multimeter on one of them, and the other is way up in the megohms range.
Seems it must be the caps, but im going to need to test these on a proper PSU now...
Re: Have my bus caps died?
Kizmo, Thu Nov 10 2016, 01:00PM
I have seen this before plenty of times. It goes like this: Upper or lower transistor goes short for whatever reason, then other transistor turns on which results dead short over your DC bus. Energy stored in your bus capacitors can and will blow up bonding wires inside your igbts and any shorts will be cleared.
IGBT brick an be totally destroyed while collector-emitter measurements appear to be within normal limits (=no shorts, antiparallel diode is still fine). Check gate connections for resistance capacitance. Healthy gate should read resistance of 100s of kOhms to Mohms and capacitance of few 10s of nF. If not the brick is most likely destroyed like this one:
This CM300 had IGBT chips completely destroyed while antiparallel diodes were fine. Diode test over C-E was normal but gate connections did not show normal capacitance (gate connection was open circuit and less than 1n of capacitance..) so i decided to cut the brick open.
Kizmo, Thu Nov 10 2016, 01:00PM
nzoomed wrote ...
OK, I have removed the caps from the DC bus, and the resistance on the IGBT's is off the scale on my multimeter on one of them, and the other is way up in the megohms range.
Seems it must be the caps, but im going to need to test these on a proper PSU now...
OK, I have removed the caps from the DC bus, and the resistance on the IGBT's is off the scale on my multimeter on one of them, and the other is way up in the megohms range.
Seems it must be the caps, but im going to need to test these on a proper PSU now...
I have seen this before plenty of times. It goes like this: Upper or lower transistor goes short for whatever reason, then other transistor turns on which results dead short over your DC bus. Energy stored in your bus capacitors can and will blow up bonding wires inside your igbts and any shorts will be cleared.
IGBT brick an be totally destroyed while collector-emitter measurements appear to be within normal limits (=no shorts, antiparallel diode is still fine). Check gate connections for resistance capacitance. Healthy gate should read resistance of 100s of kOhms to Mohms and capacitance of few 10s of nF. If not the brick is most likely destroyed like this one:
This CM300 had IGBT chips completely destroyed while antiparallel diodes were fine. Diode test over C-E was normal but gate connections did not show normal capacitance (gate connection was open circuit and less than 1n of capacitance..) so i decided to cut the brick open.
Re: Have my bus caps died?
Hydron, Thu Nov 10 2016, 01:59PM
You can check IGBTs (or at least those without short circuit protection circuitry) with a normal multimeter.
Set to diode mode, measure C (positive probe)-E (negative), keep probe connected to emitter and touch the gate with the positive probe then quickly switch it back to emitter.
If the multimeter uses a high enough voltage for diode test you should see the measurement go from out-of-range before touching the gate to something on the order of ~1-1.5V, rising as the gate capacitance discharges.
This may not work so well with large (brick) IGBTs, and almost certainly not work with anything with the "RTC Protection" circuit, but I have used with with success with smaller TO-247 IGBTs. It will also depend on the multimeter - some will not be suitable.
The other thing to test is with a current limited bench supply. Set to 10-15V at maybe 100mA or so, negative connected to emitter, repeat the procedure above with the positive lead. Should not flow current until you touch the gate, then should conduct until the gate discharges.
Edit: if it fails the multimeter test don't assume that it's dead unless others of the same type give different results. If it passes though there is a good chance that it's OK.
Hydron, Thu Nov 10 2016, 01:59PM
You can check IGBTs (or at least those without short circuit protection circuitry) with a normal multimeter.
Set to diode mode, measure C (positive probe)-E (negative), keep probe connected to emitter and touch the gate with the positive probe then quickly switch it back to emitter.
If the multimeter uses a high enough voltage for diode test you should see the measurement go from out-of-range before touching the gate to something on the order of ~1-1.5V, rising as the gate capacitance discharges.
This may not work so well with large (brick) IGBTs, and almost certainly not work with anything with the "RTC Protection" circuit, but I have used with with success with smaller TO-247 IGBTs. It will also depend on the multimeter - some will not be suitable.
The other thing to test is with a current limited bench supply. Set to 10-15V at maybe 100mA or so, negative connected to emitter, repeat the procedure above with the positive lead. Should not flow current until you touch the gate, then should conduct until the gate discharges.
Edit: if it fails the multimeter test don't assume that it's dead unless others of the same type give different results. If it passes though there is a good chance that it's OK.
Re: Have my bus caps died?
nzoomed, Fri Nov 11 2016, 01:32AM
OK, thanks for the advice.
I dont think my multimeter is very crash hot, so im going to look for a better meter.
Either way, its probably simple enough to just apply power to the DC bus with the caps removed with a low voltage 12V supply.
There should not be any current drain or shorting, so should be pretty easy to see if they are at fault that way.
nzoomed, Fri Nov 11 2016, 01:32AM
OK, thanks for the advice.
I dont think my multimeter is very crash hot, so im going to look for a better meter.
Either way, its probably simple enough to just apply power to the DC bus with the caps removed with a low voltage 12V supply.
There should not be any current drain or shorting, so should be pretty easy to see if they are at fault that way.
Re: Have my bus caps died?
Hydron, Fri Nov 11 2016, 12:36PM
run a signal generator into the feedback CT input, run the bus off a 12V PSU and you should be able to get the bridge to switch like normal (freq determined by sig gen - use something like 50-100kHz) if the IGBTs are fine
Hydron, Fri Nov 11 2016, 12:36PM
run a signal generator into the feedback CT input, run the bus off a 12V PSU and you should be able to get the bridge to switch like normal (freq determined by sig gen - use something like 50-100kHz) if the IGBTs are fine
Re: Have my bus caps died?
nzoomed, Sat Nov 12 2016, 03:23AM
I didnt even have to do that!
Ive just confirmed that one of the IGBT's has died, and now ive got to ask a few questions!
I tested both IGBT's this way here:
After testing both, i discovered one has indeed failed, but im pretty sure the other one tests OK according to these tests, but i just hope it has not suffered any damage, is it better to replace both if one has failed?
I also think i may have discovered the cause of failure, but would like your thoughts on this.
When i went to disconnect the GDT from the gates to test the IGBT's, I discovered one of the gate wires had broken off the spade connector (on the failed IGBT)
Measuring across E2 and G2 on this brick was 0 Ohms and across E1 and G1 was about 2.5 Ohms, so I knew straight away this was dead.
It does not appear to have melted off or anything, so I can only assume this bought on the failure perhaps?
I know you have to be careful when stripping this solid core cat5 cable, and i thought I had when i was assembling the inverter.
Both TVS clamps pictured here on the failed IGBT were also giving me a reading on my multimeter, when the ones on the "good" IGBT are perfectly normal and measure no conductance with my multimeter.
Anyway, ive also attached a photo of the failed IGBT brick, this was a nightmare to open, but it confirms that it has failed.
(how on earth are supposed to open these units for modification, ill never know? lol I had to destroy this to open it!)
nzoomed, Sat Nov 12 2016, 03:23AM
Hydron wrote ...
run a signal generator into the feedback CT input, run the bus off a 12V PSU and you should be able to get the bridge to switch like normal (freq determined by sig gen - use something like 50-100kHz) if the IGBTs are fine
run a signal generator into the feedback CT input, run the bus off a 12V PSU and you should be able to get the bridge to switch like normal (freq determined by sig gen - use something like 50-100kHz) if the IGBTs are fine
I didnt even have to do that!
Ive just confirmed that one of the IGBT's has died, and now ive got to ask a few questions!
I tested both IGBT's this way here:
After testing both, i discovered one has indeed failed, but im pretty sure the other one tests OK according to these tests, but i just hope it has not suffered any damage, is it better to replace both if one has failed?
I also think i may have discovered the cause of failure, but would like your thoughts on this.
When i went to disconnect the GDT from the gates to test the IGBT's, I discovered one of the gate wires had broken off the spade connector (on the failed IGBT)
Measuring across E2 and G2 on this brick was 0 Ohms and across E1 and G1 was about 2.5 Ohms, so I knew straight away this was dead.
It does not appear to have melted off or anything, so I can only assume this bought on the failure perhaps?
I know you have to be careful when stripping this solid core cat5 cable, and i thought I had when i was assembling the inverter.
Both TVS clamps pictured here on the failed IGBT were also giving me a reading on my multimeter, when the ones on the "good" IGBT are perfectly normal and measure no conductance with my multimeter.
Anyway, ive also attached a photo of the failed IGBT brick, this was a nightmare to open, but it confirms that it has failed.
(how on earth are supposed to open these units for modification, ill never know? lol I had to destroy this to open it!)
Re: Have my bus caps died?
Kizmo, Sat Nov 12 2016, 11:27AM
Now, we have some evidence right here!
Larger rectangular chips are your actual IGBT transistors. All of them have failed as you can see. But: more interesting thing is that you also have at least one diode chip that is failed in catastrophic manner. In DRSSTC there is only one reason why the antiparallel diode failes like that, and it is overvoltage.
My guess is that there was an overvoltage event that caused at least one diode short out which made opposing igbt chip to die to overcurernt and so on.
So, what may have caused the overvoltage then? Bus layout, insufficient decoupling and/or snubbering, switching timing and similar things. I had very similar CM300 failure (Diode and igbt chip damage) in past due to the 20µ plastic film decoupling capacitor failed open circuit during TC run :D
Kizmo, Sat Nov 12 2016, 11:27AM
nzoomed wrote ...
Anyway, ive also attached a photo of the failed IGBT brick, this was a nightmare to open, but it confirms that it has failed.
(how on earth are supposed to open these units for modification, ill never know? lol I had to destroy this to open it!)
Mod edit: cleaned up your double posts :)Anyway, ive also attached a photo of the failed IGBT brick, this was a nightmare to open, but it confirms that it has failed.
(how on earth are supposed to open these units for modification, ill never know? lol I had to destroy this to open it!)
Now, we have some evidence right here!
Larger rectangular chips are your actual IGBT transistors. All of them have failed as you can see. But: more interesting thing is that you also have at least one diode chip that is failed in catastrophic manner. In DRSSTC there is only one reason why the antiparallel diode failes like that, and it is overvoltage.
My guess is that there was an overvoltage event that caused at least one diode short out which made opposing igbt chip to die to overcurernt and so on.
So, what may have caused the overvoltage then? Bus layout, insufficient decoupling and/or snubbering, switching timing and similar things. I had very similar CM300 failure (Diode and igbt chip damage) in past due to the 20µ plastic film decoupling capacitor failed open circuit during TC run :D
Re: Have my bus caps died?
nzoomed, Sat Nov 12 2016, 06:38PM
Overvoltage, now thats interesting!
I wouldnt have thought that overvoltage would be possible, since these are rated at 1200V, and my maximum bus voltage would not be any more than 700VDC.
As i mentioned, I discovered one of the GDT wires from the cat5 cable was broken off the spade terminal to the gate on that very IGBT, could this have caused the failure?
Do you think the other IGBT will be OK? (it appears to test OK)
nzoomed, Sat Nov 12 2016, 06:38PM
Kizmo wrote ...
Now, we have some evidence right here!
Larger rectangular chips are your actual IGBT transistors. All of them have failed as you can see. But: more interesting thing is that you also have at least one diode chip that is failed in catastrophic manner. In DRSSTC there is only one reason why the antiparallel diode failes like that, and it is overvoltage.
My guess is that there was an overvoltage event that caused at least one diode short out which made opposing igbt chip to die to overcurernt and so on.
So, what may have caused the overvoltage then? Bus layout, insufficient decoupling and/or snubbering, switching timing and similar things. I had very similar CM300 failure (Diode and igbt chip damage) in past due to the 20µ plastic film decoupling capacitor failed open circuit during TC run :D
nzoomed wrote ...
Anyway, ive also attached a photo of the failed IGBT brick, this was a nightmare to open, but it confirms that it has failed.
(how on earth are supposed to open these units for modification, ill never know? lol I had to destroy this to open it!)
Mod edit: cleaned up your double posts :)Anyway, ive also attached a photo of the failed IGBT brick, this was a nightmare to open, but it confirms that it has failed.
(how on earth are supposed to open these units for modification, ill never know? lol I had to destroy this to open it!)
Now, we have some evidence right here!
Larger rectangular chips are your actual IGBT transistors. All of them have failed as you can see. But: more interesting thing is that you also have at least one diode chip that is failed in catastrophic manner. In DRSSTC there is only one reason why the antiparallel diode failes like that, and it is overvoltage.
My guess is that there was an overvoltage event that caused at least one diode short out which made opposing igbt chip to die to overcurernt and so on.
So, what may have caused the overvoltage then? Bus layout, insufficient decoupling and/or snubbering, switching timing and similar things. I had very similar CM300 failure (Diode and igbt chip damage) in past due to the 20µ plastic film decoupling capacitor failed open circuit during TC run :D
Overvoltage, now thats interesting!
I wouldnt have thought that overvoltage would be possible, since these are rated at 1200V, and my maximum bus voltage would not be any more than 700VDC.
As i mentioned, I discovered one of the GDT wires from the cat5 cable was broken off the spade terminal to the gate on that very IGBT, could this have caused the failure?
Do you think the other IGBT will be OK? (it appears to test OK)
Re: Have my bus caps died?
dexter, Sat Nov 12 2016, 07:53PM
i had the same problem before (one disconnected gate) and the IGBT's failed even at a lower buss voltage
i had this problem for a half bridge with discrete IGBT's but i guess but i guess your other IGBT brick has survived
dexter, Sat Nov 12 2016, 07:53PM
nzoomed wrote ...
As i mentioned, I discovered one of the GDT wires from the cat5 cable was broken off the spade terminal to the gate on that very IGBT, could this have caused the failure?
Do you think the other IGBT will be OK? (it appears to test OK)
As i mentioned, I discovered one of the GDT wires from the cat5 cable was broken off the spade terminal to the gate on that very IGBT, could this have caused the failure?
Do you think the other IGBT will be OK? (it appears to test OK)
i had the same problem before (one disconnected gate) and the IGBT's failed even at a lower buss voltage
i had this problem for a half bridge with discrete IGBT's but i guess but i guess your other IGBT brick has survived
Re: Have my bus caps died?
Hydron, Mon Nov 21 2016, 08:16AM
Appears that this is a tried and tested way of killing bricks (see link above)
Hydron, Mon Nov 21 2016, 08:16AM
Appears that this is a tried and tested way of killing bricks (see link above)
Re: Have my bus caps died?
nzoomed, Mon Nov 21 2016, 08:29AM
OK, very interesting, at least its not just me!
Now ive got to wait for my IGBT replacement to arrive.
Im wondering if soldering directly to the IGBT is a better idea?
Either way, I dont like using cat5 cable for the GDT, but i dont think there is any better option, you just have to be careful when stripping the stuff.
nzoomed, Mon Nov 21 2016, 08:29AM
Hydron wrote ...
Appears that this is a tried and tested way of killing bricks (see link above)
Appears that this is a tried and tested way of killing bricks (see link above)
OK, very interesting, at least its not just me!
Now ive got to wait for my IGBT replacement to arrive.
Im wondering if soldering directly to the IGBT is a better idea?
Either way, I dont like using cat5 cable for the GDT, but i dont think there is any better option, you just have to be careful when stripping the stuff.
Re: Have my bus caps died?
Finn Hammer, Mon Nov 21 2016, 08:54AM
Nzoomed,
When you strip the cat5 cable, it is difficult to avoid circumscribing a nick into the copper, and later on, this point is likely to break off.
One way to avoid this is, to solder a length of multistrand wire to the end of the cat5, and heatshrink that connection.
The benefit of this is, that the multistrand wire is flexible, and unlikely to transfer a bending momentum to the solid cat5 wire, therefore making it less prone to breaking.
Another benefit is, that you can colour code the gate wire to make it straightforward to phase the bridge.
Hope this helps.
Cheers, Finn Hammer
Finn Hammer, Mon Nov 21 2016, 08:54AM
Nzoomed,
When you strip the cat5 cable, it is difficult to avoid circumscribing a nick into the copper, and later on, this point is likely to break off.
One way to avoid this is, to solder a length of multistrand wire to the end of the cat5, and heatshrink that connection.
The benefit of this is, that the multistrand wire is flexible, and unlikely to transfer a bending momentum to the solid cat5 wire, therefore making it less prone to breaking.
Another benefit is, that you can colour code the gate wire to make it straightforward to phase the bridge.
Hope this helps.
Cheers, Finn Hammer
Re: Have my bus caps died?
Kizmo, Mon Nov 21 2016, 10:15AM
It works really well for normal PVC installation wire :D
Kizmo, Mon Nov 21 2016, 10:15AM
Finn Hammer wrote ...
Nzoomed,
When you strip the cat5 cable, it is difficult to avoid circumscribing a nick into the copper, and later on, this point is likely to break off.
One way to avoid this is, to solder a length of multistrand wire to the end of the cat5, and heatshrink that connection.
The benefit of this is, that the multistrand wire is flexible, and unlikely to transfer a bending momentum to the solid cat5 wire, therefore making it less prone to breaking.
Another benefit is, that you can colour code the gate wire to make it straightforward to phase the bridge.
Hope this helps.
Cheers, Finn Hammer
I like to strip small single strand wires with my fingernails.Nzoomed,
When you strip the cat5 cable, it is difficult to avoid circumscribing a nick into the copper, and later on, this point is likely to break off.
One way to avoid this is, to solder a length of multistrand wire to the end of the cat5, and heatshrink that connection.
The benefit of this is, that the multistrand wire is flexible, and unlikely to transfer a bending momentum to the solid cat5 wire, therefore making it less prone to breaking.
Another benefit is, that you can colour code the gate wire to make it straightforward to phase the bridge.
Hope this helps.
Cheers, Finn Hammer
It works really well for normal PVC installation wire :D
Re: Have my bus caps died?
Hydron, Mon Nov 21 2016, 10:38AM
You could also use stranded CAT5e (the stuff for patch cables). Less likely to run into issues with that (is what I use). Finn's suggestion is also good.
Hydron, Mon Nov 21 2016, 10:38AM
You could also use stranded CAT5e (the stuff for patch cables). Less likely to run into issues with that (is what I use). Finn's suggestion is also good.
Re: Have my bus caps died?
Alex Yuan, Tue Nov 22 2016, 12:37AM
Personally I have never used spade connectors on IGBT gates because 1. I didn't have any and 2. I don't trust them. I've just been soldering them directly. I've also been using solid CAT5e cables with no problems. Depending on the insulation type, even if you knick it while stripping it, when you solder the wire the insulation will shrink back a bit and you'll end up covering the knick with solder anyway so that wasn't ever an issue for me either.
How are you sourcing your IGBT's? I just checked eBay here in the USA and I can get some surplus for $25 a piece plus $8 shipping. I'm sure there's a way we could help you out so that you aren't paying 300NZD ($212 USD) for two CM300s.
Speaking of CM300's you can push them further than 750A... that's almost in spec even! I push my CM200s up to 900A at 100kHz...
Alex Yuan, Tue Nov 22 2016, 12:37AM
Personally I have never used spade connectors on IGBT gates because 1. I didn't have any and 2. I don't trust them. I've just been soldering them directly. I've also been using solid CAT5e cables with no problems. Depending on the insulation type, even if you knick it while stripping it, when you solder the wire the insulation will shrink back a bit and you'll end up covering the knick with solder anyway so that wasn't ever an issue for me either.
How are you sourcing your IGBT's? I just checked eBay here in the USA and I can get some surplus for $25 a piece plus $8 shipping. I'm sure there's a way we could help you out so that you aren't paying 300NZD ($212 USD) for two CM300s.
Speaking of CM300's you can push them further than 750A... that's almost in spec even! I push my CM200s up to 900A at 100kHz...
Re: Have my bus caps died?
nzoomed, Tue Nov 22 2016, 04:29AM
I was searching for them on ebay (CM300DY-24H), and the cheapest ones i could find from china were around $98 USD.
I know there are a few variants in the CM300 series, and some have to be modified to work properly for TC use.
I think there is a 24F etc? the 24NFH i think need the modification inside.
Are you sure you are not referring to the 600V version (12H?) I know these are alot cheaper.
Anyway, thanks for everyone's suggestions, I too had been thinking of soldering stranded wire to the ends, and i think i will modify all the remaining connections this way and solder to the gates.
I had seen spade terminals used on other projects, and naturally thought that was a good idea.
There is stranded cat5/6 cable available, as is used in patch leads etc.
I was not sure if this stuff was suitable, i know from using the stranded stuff in the past that there is not much wire to play around with either.
As far as current goes, yes I know they can handle much more than 750A.
I actually want to upgrade the coil to take more, main thing is the MMC will need to be beefed up, it can only take about 850A max currently.
nzoomed, Tue Nov 22 2016, 04:29AM
Alex Yuan wrote ...
Personally I have never used spade connectors on IGBT gates because 1. I didn't have any and 2. I don't trust them. I've just been soldering them directly. I've also been using solid CAT5e cables with no problems. Depending on the insulation type, even if you knick it while stripping it, when you solder the wire the insulation will shrink back a bit and you'll end up covering the knick with solder anyway so that wasn't ever an issue for me either.
How are you sourcing your IGBT's? I just checked eBay here in the USA and I can get some surplus for $25 a piece plus $8 shipping. I'm sure there's a way we could help you out so that you aren't paying 300NZD ($212 USD) for two CM300s.
Speaking of CM300's you can push them further than 750A... that's almost in spec even! I push my CM200s up to 900A at 100kHz...
If you can provide me the link to one of those listings, that would be great!Personally I have never used spade connectors on IGBT gates because 1. I didn't have any and 2. I don't trust them. I've just been soldering them directly. I've also been using solid CAT5e cables with no problems. Depending on the insulation type, even if you knick it while stripping it, when you solder the wire the insulation will shrink back a bit and you'll end up covering the knick with solder anyway so that wasn't ever an issue for me either.
How are you sourcing your IGBT's? I just checked eBay here in the USA and I can get some surplus for $25 a piece plus $8 shipping. I'm sure there's a way we could help you out so that you aren't paying 300NZD ($212 USD) for two CM300s.
Speaking of CM300's you can push them further than 750A... that's almost in spec even! I push my CM200s up to 900A at 100kHz...
I was searching for them on ebay (CM300DY-24H), and the cheapest ones i could find from china were around $98 USD.
I know there are a few variants in the CM300 series, and some have to be modified to work properly for TC use.
I think there is a 24F etc? the 24NFH i think need the modification inside.
Are you sure you are not referring to the 600V version (12H?) I know these are alot cheaper.
Anyway, thanks for everyone's suggestions, I too had been thinking of soldering stranded wire to the ends, and i think i will modify all the remaining connections this way and solder to the gates.
I had seen spade terminals used on other projects, and naturally thought that was a good idea.
There is stranded cat5/6 cable available, as is used in patch leads etc.
I was not sure if this stuff was suitable, i know from using the stranded stuff in the past that there is not much wire to play around with either.
As far as current goes, yes I know they can handle much more than 750A.
I actually want to upgrade the coil to take more, main thing is the MMC will need to be beefed up, it can only take about 850A max currently.
Re: Have my bus caps died?
Alex Yuan, Tue Nov 22 2016, 07:02PM
Not the F version (you won't need to cut out the RTC!), but also not the NFH version (slower) but I don't think there's any issue with using them in a coil.
Alex Yuan, Tue Nov 22 2016, 07:02PM
Not the F version (you won't need to cut out the RTC!), but also not the NFH version (slower) but I don't think there's any issue with using them in a coil.
Re: Have my bus caps died?
Hydron, Tue Nov 22 2016, 09:30PM
This is the seller i bought my MMC caps off (48x 2uF 1kV Aerovox snubbers). They couldn't ship to NZ but i got them sent via Youshop ( ) which cost about $100 but didn't have much other choice. They were nice and friendly and gave me an approximate size of the box before I hit "Buy Now".
Hydron, Tue Nov 22 2016, 09:30PM
Alex Yuan wrote ...
Not the F version (you won't need to cut out the RTC!), but also not the NFH version (slower) but I don't think there's any issue with using them in a coil.
Not the F version (you won't need to cut out the RTC!), but also not the NFH version (slower) but I don't think there's any issue with using them in a coil.
This is the seller i bought my MMC caps off (48x 2uF 1kV Aerovox snubbers). They couldn't ship to NZ but i got them sent via Youshop (
) which cost about $100 but didn't have much other choice. They were nice and friendly and gave me an approximate size of the box before I hit "Buy Now".Re: Have my bus caps died?
Alex Yuan, Tue Nov 22 2016, 10:14PM
Yup, I've bought snubber caps from them before too. As well as a bunch of electrolytics. No problems with them.
Alex Yuan, Tue Nov 22 2016, 10:14PM
Hydron wrote ...
This is the seller i bought my MMC caps off (48x 2uF 1kV Aerovox snubbers). They couldn't ship to NZ but i got them sent via Youshop ( ) which cost about $100 but didn't have much other choice. They were nice and friendly and gave me an approximate size of the box before I hit "Buy Now".
This is the seller i bought my MMC caps off (48x 2uF 1kV Aerovox snubbers). They couldn't ship to NZ but i got them sent via Youshop (
) which cost about $100 but didn't have much other choice. They were nice and friendly and gave me an approximate size of the box before I hit "Buy Now".Yup, I've bought snubber caps from them before too. As well as a bunch of electrolytics. No problems with them.
Re: Have my bus caps died?
Kizmo, Wed Nov 23 2016, 03:02PM
I can offer same bricks (CM300DY-24H) from my collection at about same price too i you want :)
Kizmo, Wed Nov 23 2016, 03:02PM
I can offer same bricks (CM300DY-24H) from my collection at about same price too i you want :)
Re: Have my bus caps died?
nzoomed, Wed Nov 23 2016, 09:21PM
nzoomed, Wed Nov 23 2016, 09:21PM
Kizmo wrote ...
I can offer same bricks (CM300DY-24H) from my collection at about same price too i you want :)
OK, I could be interested :)I can offer same bricks (CM300DY-24H) from my collection at about same price too i you want :)
Re: Have my bus caps died?
Kizmo, Thu Nov 24 2016, 06:41AM
ok, PM me :)
Kizmo, Thu Nov 24 2016, 06:41AM
ok, PM me :)
Re: Have my bus caps died?
nzoomed, Sat Jul 22 2017, 05:47AM
Hi everyone, just getting back to my project after many months.
I ended up buying another IGBT off ebay and reassembled my coil again today.
No idea what's wrong, but my coil is no longer working since one of the IGBT's died.
Is there anything else i should be checking after an IGBT failure?
I believe the failure was caused on a floating gate, as i discovered that one of the cat 5 wires from the GDT had broken off the failed IGBT.
Im still getting a signal on the scope on the GDT outputs and on the bridge output itself also.
The scope shot below is taken from across the bridge, and the odd thing is i get the same waveform even if i remove the power from the bus!
Dont know whats going on here, but i think i might try and inject a signal from the signal generator into the UD board and see if that makes any difference. Right now my MIDI interrupter is simply emulating a spark gap coil in this screenshot.
Either way, i can hear the GDT making the usual buzzing noise when its being driven, so the feedback driver must be doing something right.
Any ideas?
TIA
=
nzoomed, Sat Jul 22 2017, 05:47AM
Hi everyone, just getting back to my project after many months.
I ended up buying another IGBT off ebay and reassembled my coil again today.
No idea what's wrong, but my coil is no longer working since one of the IGBT's died.
Is there anything else i should be checking after an IGBT failure?
I believe the failure was caused on a floating gate, as i discovered that one of the cat 5 wires from the GDT had broken off the failed IGBT.
Im still getting a signal on the scope on the GDT outputs and on the bridge output itself also.
The scope shot below is taken from across the bridge, and the odd thing is i get the same waveform even if i remove the power from the bus!
Dont know whats going on here, but i think i might try and inject a signal from the signal generator into the UD board and see if that makes any difference. Right now my MIDI interrupter is simply emulating a spark gap coil in this screenshot.
Either way, i can hear the GDT making the usual buzzing noise when its being driven, so the feedback driver must be doing something right.
Any ideas?
TIA
=
Re: Have my bus caps died?
nzoomed, Sat Jul 22 2017, 05:49AM
photo
nzoomed, Sat Jul 22 2017, 05:49AM
photo
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