duc=zi+ILt dt di L1"="c-(in+i2)R1+s dt L2D2=uc-(i1+i12)R1+s-R2(i+i12) dt 儿L LI R R,\ialL C 2 RI R1+ R2 2 1R, dt 2 2                        − +                             + − − − − − − =                 s s L L C L L C i u L R L L i i u L R R L R L L R L R L C C d t d i d t d i d t d u 2 2 2 1 2 1 2 1 2 2 1 2 1 1 1 1 1 2 1 1 0 1 0 0 1 1 1 1 0 L1 L2 C i i dt du −C = + C L L S L u i i R u dt di L = − 1 + 2 1 + 1 1 ( ) ( ) ( ) 1 2 1 2 2 2 2 C L L S S L L u i i R u R i i dt di L = − + + − +  C i   uL1 R i