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不知道是驱动波形导致变压器原边电流不稳,还是变压器原边电流导致驱动占空比不稳???

Other Parts Discussed in Thread: UCC28950

采用ucc28950的移向全桥整流DC-DC,输入电压390V,输出390V,5A时,采集到的驱动波形和变压器原边波形是这样的,可能是什么原因???

 

震荡频率从图上看好像是10几K的;

在小电流(1A)输出的情况下没发现这种情情况 ;

电流采样电阻选择的是0.005Ω,然后经INA213芯片后在分压到EA-端口。和采样电阻阻值小有关??