5、正弦稳态电路的功率 有功(平均)功率:P= Ul cos o 无功功率:Q= UI o 视在功率:S=UI 复功率:S=UI=P+jQ P=UI cOSp=12Zcosp=12R =Resi an p e=Ulsinp =1ZsinP =12X=Ptanp=Im(SI SES 2 P +o S=UI=IIZ=Z=UY DOWNUP DOWN 5、正弦稳态电路的功率 有功(平均)功率: P =UI cosφ S = U I = P + jQ • • 复功率: 无功功率: Q =UIsinφ 视在功率: S = UI P = UI cos cos 2 = I Z I R 2 = tan Q = = Re[S] Q = UIsin sin 2 = I Z I X 2 = = P tan = Im[ S] S = S 2 2 = P + Q • • S = U I I I Z • • = I Z 2 = = U Y 2