Has anyone experienced having the input current oscillating when using the UCC28070? We have followed the excel spreadsheet for resistor and capacitor values. it is a 1800 Watt design and the oscillation occur as we increase the ac input voltage from 0Vac. First we power the lvps then we put ~100Vdc on the pfc bus to allow the drives to start as the ac input is increased from 0Vac. We have about a 300 watt load on the bus.
The drives look good and it seems to work as expected until ~30Vac input. At that time a slight overshoot appears at about 30-40 degrees into the 120Hz cycle. As the input is increased the oscillations become worse and the entire input current waveform oscillates at around 1.6kHz. Both leaves are doing the same thing, also they do it if one side is disconnected and only one side is boosting.
Has anyone dealt with this type of behavior? Any help would be appreciated, we already invested considerable time into this IC and do not want to start over with something else unless absolutely necessary.
Thanks,
Steve
