R r LSu 4、求电感电压: t 解一:l1=L Ll(I-er dt L R t>0 解二:l1=(15-i)R=[s-s(1-e)R Rle tt>o解一: dt di u L L L = ( 1 ) t S I e dtd L − = − t S LI e − = 1 , 0 t RI e t S − = 解二: u L = ( IS − iL ) R [ I I ( 1 e ) R ] t S S − = − − , 0 t RI e t S − = O t u L RI S 4、求电感电压: R L +_uL i L i R I S