I don't have any yetWhere are your decoupling caps?
It's generated by a microcontroller, then entering a driver that is connected to the on/off resistors R3-6Where is your waveform from?
I don't have any, it's a bird nest, no breadboard, only soldering.Where is your PCB layout?
I don't know if I used the correct technical term, so I have marked it in red.Where is your overshoot?
What are your driving signals?
I'm using 1EDC20I12AHXUMA1 as driver with single supply +15V, and the outputs are connected to the on/off resistors R3-6
Since my last post I removed the RCD snubber and changed values of R3-6, then I got rid of the turn-on "overshoot", but I still have a problem with turn-off.
The yellow trace is "OUT" and I'm using a 1000x probe, so you have to multiply by 1000
Hi kripacharya, please see my reply to barryYour circuit and scope trace is not understand able as presented. Please add details to better explain the problem, the investigations done, and the results obtained so far - with proper cross reference to your diagrams.
Yes, this is the gate signalI see you are switching on & off quite slowly with those high-ish gate resistors
I tried with a 0.1uF (didn't have 1uF) and the only thing it seems to do is to distort the positive cycle.I - but you still need 1uF 630V say across the pair of IGBT's from top collector to bottom emitter to soak up the turn off wiring inductance energy
Like this?I zoom right in on those over shoots for a good look ( 500nS/div & 100nS/div ) it may be just CM pickup ... how many amps are you trying to switch ?
At the moment around 3-400mAhow many amps are you trying to switch ?
I know, but it's too ugly to show to other people. And I'm not asking for miracles, just a few hints and pointers from experienced people would be appreciated.I - without seeing the entire schematic and a picture of the hardware - it is hard to make positive suggestions ...
I'm sorry about that, but it's my first attempt at an IGBT application, and I didn't have anyone else to ask before posting.No decoupling caps and no PCB, and you're wondering why your circuit works like crap???
You are probably right about that.You probably have a LOT of stray inductance, not to mention inductance from the ground probe of your oscilloscope.
I recommend to read some MOSFET or IGBT driving tutorials.The plateaus disappear if I turn off V1 and V2, what could cause that?
I've been searching for decoupling caps for IGBT like 1 hour a day like 2-3 days. I checked many tutorials, datasheets and application notes. I haven't seen any decoupling capacitors.Where are your decoupling caps?
That's basically putting a capacitor at source.but you still need 1uF 630V say across the pair of IGBT's from top collector to bottom emitter to soak up the turn off wiring inductance energy
Do you mean there will be an energy stored in PCB because of an stray inductance and bypass it via that capacitor ? What if the input is AC not DC ?soak up the turn off wiring inductance energy
I searched many manufacturer IGBT tutorials, application notes, datasheets, datasheet tutorials, miller plateau voltage papers and now I'm confused like a cat watching pinball game. Could you please point out a spesific tutorial so I can print out and read line by line.Hi,
Your document is about snubbers, whuch ar connected at the output of a Mosfet / IGBT.
But I recommended a "driving" tutorial, which is at the input, the gate.
The plateau is called "miller plateau". Do an internet search, you will find a lot of informations.