Swend
Full Member level 4
- Joined
- May 14, 2019
- Messages
- 237
- Helped
- 10
- Reputation
- 20
- Reaction score
- 9
- Trophy points
- 18
- Location
- Roskilde, Denmark
- Activity points
- 2,304
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Where are your decoupling caps?
Where is your waveform from?
Where is your PCB layout?
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
Your 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.
I see you are switching on & off quite slowly with those high-ish gate resistors
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
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 ?
how many amps are you trying to switch ?
I - without seeing the entire schematic and a picture of the hardware - it is hard to make positive suggestions ...
No decoupling caps and no PCB, and you're wondering why your circuit works like crap???
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?
Hi,
I recommend to read some MOSFET or IGBT driving tutorials.
The plateau should be well explained in every good tutorial.
Klaus
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
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.
Klaus