求开路电压U 3g2 U 62× 45V 49 U=U,+ 29U =30-9=21V b 392 a U1"+U2 oc 62U1〃 =0+12=12V 15A 22U U=0+ o b 21+12=33VUoc'=U1'+U2' =30-9=21V Uoc''=U1''+U2'' =0+12=12V Uoc=Uoc’+Uoc'’ =21+12=33V 求开路电压Uoc: ab Uoc' Us 45V3 4 62 4 +- +- +-U1' +-U2' ab Uoc'' Is 15A3 4 62 4 +- +-U1'' +-U2