Other Parts Discussed in Thread: TMDSCNCD28379D
Hi,
I am trying to scale up the Vienna rectifier design for higher voltage and current operation.
I have built a 440V 15kW rectifier using 1200V SiC Mosfets & Diodes with inductor and capacitor values scaled according to the TIDM-1000 Calculation spreadsheet (higher voltage capacitors obviously).
I am using the same board ("TMDSCNCD28379D F28379D controlCARD for C2000 Real time control development kits") for the control that I used with the evaluation kit, running the same Vienna application, in debug from the laptop
I have scaled the application to correctly monitor my ac voltage sense and currents (and set my current limit) successfully from the main.cfg page.
The setup has, so far, worked very well as I have, in small steps, increased the applied ac voltage and the dc voltage set-point, with a 48Ω load on the dc. Stable dc operation, <2% THD currents, unity power factor. I got up to 440V input with the VDC set to 700V (10.3kW) without issues
But I believe, in order to regulate with the worst-case (highest) tolerance on my 440V supply, I will need to set the VDC above 700V, so for my next step, I left the input at 440 and set the dc ref to 720V
In this case it would always work perfectly for approx 1.3 seconds, and then just stop: no fault message in the Expressions list, still reading "BoardStatus_NoFault"
I see in the vienna_settings.h file, line 184 reads #define VIENNA_VBUS_TRIP_LIMIT_VOLTS ((float32_t)720.0)
So is 720V a safety limit on the buss? and it does not give a fault message in the debug expressions window? Does my observed 1.3 sec delay make sense? Note that I accidentally ran it nearer 740V one time and it shut down in the same way (no fault message after controlling ok) but this time after less than 0.5sec
So with my higher voltage-rated circuit, assuming my power components, gate drives etc are adequate, if I edit this line of this file to change the 720V value to, say, 750V, will this allow me to run at a higher dc bus? Or is there some extra complexity? I believe I need to generate a buss somewhere around 730V to allow the regulation to work at my worst-case (highest) input voltage.
Thank you for your help
Chris