2 ao AoT a 2(7S+1) TS+1 S+0 s1+72 t Uo(t=eT+d e o+,el lim U(t=d,e jot +d,elor t→o0 △sn(o- arcola 1+Ta2 这里应用欧拉公式sm=° 22 2 2 2 2 1 ( 1) 1 s 1 a 1     T A T Ts a Ts T s + + = +  + = =− j e t arctgT U t d e d e e d e d e j j t j t j t j t T t 2 e sin sin( ) lim ( ) U (t) j 1 T A 0 1 2 t T 1 2 a 0 2 2           − + − → − − − = = − = + = + + 这里应用欧拉公式