TIDUF22 January 2023
Figure 3-13 shows the AC drop at 90°, 10-ms duration, after AC voltage recover. PLL still needs time to be in the same phase with AC input, so there is an inrush current since the DC bus voltage drops a lot and PLL is out of phase, then cycle-by-cycle current protection starts to work at this time to protect GaN from overcurrent (40 A in this design).
Figure 3-14 shows the AC drop at 45°, 10-ms duration. Cycle-by-cycle current protection also works.