STSPIN32G4 buck output dropped trigger uvlo protection

[XShiy.1]

I use Internal comparator trigger Timer etr function to impelement cycle-by-cycle current mode control. I got uvlo protection when motor at heavy load(~40A pk).But when i use voltage control ,it would not occur. Does any one occur this problem?

GHSU-OUTU(yellow),OUTU(red),GLSU(blue),Buck VCC(green)

GHSV-OUTV(yellow),OUTV(red),GLSV(blue),Buck VCC(green)Phase Current