mike buba
Member level 3
Hi All,
Last time, when I worked on a 2-level inverter, I experienced significant ringing (all documented in this thread). Finally, thanks to the support from the Forum, I was able to reduce the ringing by adding snubbers and capacitors (final solution).
Now I am planning to do a SiC MOSFET 3-level T-type 3-phase inverter and do it 'properly' from the start by adding enough snubbers and capacitors in advance to reduce all potential ringing, especially since this time the switching frequency will be between 30 kHz and 50 kHz, compared to 5 kHz for the 2-level inverter last time.
Well, to be honest, I would like to avoid ringing at all, if possible. But until then, snubbers and capacitors seem to help.
Can you please advise if I missed any capacitors or RC filter circuits in the T-type schematics below? There is a 3.3 µF and series 2.2 Ω and 10 nF across DC+ and DC-. Do I need to add anything across the bidirectional switches to the midpoint (e.g., V7 and V8)?
I have found online a few T-type inverters from Texas Instruments and Wolfspeed, but they do not use any snubbers. Not sure why and how their work.
Last time, when I worked on a 2-level inverter, I experienced significant ringing (all documented in this thread). Finally, thanks to the support from the Forum, I was able to reduce the ringing by adding snubbers and capacitors (final solution).
Now I am planning to do a SiC MOSFET 3-level T-type 3-phase inverter and do it 'properly' from the start by adding enough snubbers and capacitors in advance to reduce all potential ringing, especially since this time the switching frequency will be between 30 kHz and 50 kHz, compared to 5 kHz for the 2-level inverter last time.
Well, to be honest, I would like to avoid ringing at all, if possible. But until then, snubbers and capacitors seem to help.
Can you please advise if I missed any capacitors or RC filter circuits in the T-type schematics below? There is a 3.3 µF and series 2.2 Ω and 10 nF across DC+ and DC-. Do I need to add anything across the bidirectional switches to the midpoint (e.g., V7 and V8)?
I have found online a few T-type inverters from Texas Instruments and Wolfspeed, but they do not use any snubbers. Not sure why and how their work.
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