《电路》（英文版）9-1 Instantaneous power

89-1 Instantaneous power P=vi--(passive sign convention) R--PR=Ui=iR=U/R L--Pr=Ui=Lidi/dt C--P=ui=Cudb/dt R i The current response: i(t)=Im cos(at+9) us=Vm cos af L 9=-tan R+0- R p=ui=Mlm cos at cos(@t+9) n cos 9+ n cos(2at +9) 2 2 VI 9+VIcos20t+9)=vI cos 9+vi cos scos 2at-vI sin sin 2ot (R) L or C)

§ 9-1 Instantaneous power i − +  N P=vi--(passive sign convention) R pR i i R / R 2 2 − − = = = L p i Lidi dt L − − = = / C p i C d dt C − − = =   / The current response: i(t) = Im cos( t +) = VI cos +VI cos(2 t +) p = i =Vm Im cos t cos( t +) V t  s = m cos − + R i L = VI cos +VI cos cos 2 t −VIsin sin2 t cos(2 ) 2 cos 2 =  +  t + Vm Im Vm Im ( , tan ) 1 2 2 2 R L R L V I m m    − = − + = (R) (L or C)