P(t)=()i(t)= 吸收功率 t<0 2t 0≤t<ls 2t-41<t<2s 0 2 t/s t≥2s 释放功率 w(t) L wd 0 t<0 O<t<Is 2)21≤t≤2s 2 t/s 0 t>2S        −      = = = t s t t s t t s t p t u t i t 0 2 2 4 1 2 2 0 1 0 0 ( ) ( ) ( ) 1 2 t /s 2 0 p/W -2         −      = = = t s t t s t t s t W t Cu t C 0 2 2 1 2 0 1 0 0 2 1 2 2 2 ( ) ( ) ( ) 2 1 t /s 1 0 WC/J 吸收功率 释放功率