电路升本辅导ppt课件

1、第第8 8章章 相量法相量法 本章重点本章重点FbReImao |F|8.1 复数复数baFj) 1(j为虚数单位为虚数单位j|eFF bajFeFFj)sin(cos|j|jFeFFFbReImao |F|baFj|jFeFFab baFarctan | 22sin| cos| F bFa图解法图解法F1F2ReImoF1+F2-F2-F2F1ReImoF1-F2F1+F2F2那么那么: :模相乘模相乘角相加角相加模相除模相除角相减角相减2121)21( j212j21j121 FFeFFeFeFFF2121)21j(212j21j1221121 | | |F|FeFFeFeFFFFF解解解

2、解?2510475)226. 4 j063. 9()657. 3 j41. 3(原式原式61. 248.12365 .2255 .132j5 .182329. 6 j238. 22 .126j2 .18016.70728. 62 .126j2 .1802 .126j2 .180 原原式式04.1462.203 .56211. 79 .2724.19?5 j20j6)(4 j9)(17 35 220 FReIm0F ejq 旋转因子旋转因子特殊旋转因子特殊旋转因子ReIm0FjFjFF留意留意j2sinj2cos ,22jej)2sin(j)2cos(,22je1)sin(j)cos(,jei(

3、t)=Imcos(w t+y)ti0TTf1正弦量为周期函数正弦量为周期函数 f(t)=f ( t+kT )波形波形)cos()(kn1kktkAtf i(t)=Imcos(w t+y) Tf22普通规定：普通规定：| | 。 =0 = /2留意留意解解)10cos(100)(3tticos100500t33)310cos(100)(3tti有有最最大大值值当当 310 13tms047. 110331t等于初相位之差等于初相位之差 tu, iu iuuiij joj j ( (180o ) 180o ) ，反相反相 tu io tu io tu io同样可比较两个电压或两个电流的相位差。同样

4、可比较两个电压或两个电流的相位差。R直流直流I IR交流交流 i20( )dTWRitt2WRI TTttiTI02defd)(1TttuTU02defd)(1TtttttTTT2121 d2) (2cos1d ) (cos 0002II2 mttITITd ) (cos1022m) cos(2) cos()(mtItItimm2m707. 0221 IITITIUUUU2 21mm或或UUuIIi, ,mmRLC+- -uCiLu+- -)(dddd22tuutuRCtuLCCCC) cos(2111tIi) cos(2222tIi正弦量正弦量复数复数变换的思想变换的思想无物理意义无物理意义

5、) j(2)(tIetF) sin(2j) cos(2tItI)() cos(2)(RetitItF) j(2)( ) cos(2tIetFtIi复常数复常数 ) cos(2)(IItItitte IeIetFjjj22)(试用相量表示试用相量表示 i, u i, u。解解解解A )15314cos(250ti. 50Hz A,1550 fI已知已知V60220 A,30100oo UI)V6014t311.1cos(3A)30314cos(4 .141oouti ) cos(2)(UUtUtuIItIti) cos(2)(UUtUtu) cos(2)(UIttttteUUeUeUeUeUtu

6、tutu j11 j2 j1 j2 j121)(2Re)22Re()2Re()2Re()()()(U21UUU)2Re() cos(2)()2Re() cos(2)( j2222 j1111tteUtUtueUtUtu321 IIIV604 V 306o2o1UUV )9 .41314cos(264. 9)()()( o21ttututuV )60314cos(24)(V )30314cos(26)(o21ttuttu60430621UUU46. 3 j23 j19. 546. 6 j19. 7V 9 .4164. 9o借助相量图计算借助相量图计算+1+j301U602U9 .41U首尾相接首

7、尾相接+1+j9 .41U602U301UV604 V 306o2o1UU2 jddiIIti2 jdiIIti ) cos(2iiIItIi j2Re 2Redddd j jtteIe IttitteIte Iti j jj2Re d 2Red相量法的优点相量法的优点 ) cos(2)(itIti d1dd)(tiCtiLRitu jjCIILIRU留意留意不不适适用用线线性性线线性性非非线性线性uR(t)i(t)R+- -UR uIRUR)cos(2)( itIti)cos(2)()( RitRItRituiiRIUIIR R+- -IRU 波形图及相量图波形图及相量图 i touRpRU

8、RIiupRR) (cos222RitIU) (2cos1 RitIUIRUIXILULLjj有效值关系：有效值关系： U=w L I相位关系：相位关系： u= i +90 i(t)uL(t)L+- -2 iLiLIUII) cos(2)( itIti)2 cos( 2 ) sin(2d)(d)(iiLtILtILttiLtuIj L+LU XL开路;开路;短路短路(直流)(直流) , ,; , 0 ,0LLXX ,jjILIXULULULUBILj11jj t iouLpL2电压超前电压超前电流电流900900) (2sin ) sin()cos( LmLmLLiiitIUttIUiupIL

9、UIXICUCj1j)cos(2)( utUtu)2 cos(2 ) sin(2d)(d)(CuutCUtCUttuCti2 uCuCUIUUC I UCj1 |XC| 1jjCICIXU CjjBCUUI t iCoupC电流超前电流超前电压电压9009002)(2sin )sin()cos(2CCCuuuCtUIttUIuipCIU 流入某一结点的一切正弦电流用相量表示流入某一结点的一切正弦电流用相量表示时仍满足时仍满足KCLKCL；而任一回路一切支路正弦电压用；而任一回路一切支路正弦电压用相量表示时仍满足相量表示时仍满足KVLKVL。 0)(ti0 2Re)( j21teIIti0I0U

10、 0)(tuLiu . 1UI005 cos5 . 2timm j . 3CUImULLL . 4IUXmmIUIU j . 5CCCIUCj1LL j . 6ILUtiCudd . 7LU?I0max=?A0?解解A16 ,A8 ,j . 4 210C2IIIXZA268 ,j 3. min0C2IXZA1468 2. max02IRZ，A1068 1. 220I为何参数为何参数2L1 ,j . 4 ZXZ 为为何何参参数数2L1 ,j 3. ZXZ 为何参数为何参数21 , 2. ZRZ CXZRZj , . 1 21若若0I1,IU2I例例3解解相量模型相量模型+_15Wu4H0.02F

11、i)(:),5cos(2120)( titt u求求已已知知00120U20j54 jjLX10j02. 051jjCXj20W-j10W-j10W+_15WIU1I2I3ICLCLRjjXUXURUIIIIA9 .36106812681012011511200jjjjjA)9 .365cos(210)( 0tt ij20W-j10W-j10W+_15WIU1I2I3I例例4 4解解相量模型相量模型)(:),1510cos(25)( 06tuttiS求求已已知知0155I5 j102 . 0101jj66CX()V3022545251555 j51550000CRSUUU+_5W-j5WUIR.,UICUSU例例5 5解解I40jI30BCUABUACUj40WjXL30WCBA? ,V78 ,V50 BCACABUUU：问问已已知知IIIU50)40()30(22ABV40 ,V30 ,A1RLUUI2BC2AC)40()30(78UUV3240)30()78(22BCUI解法解法1 1252505LLXX2102502552505CXRR) j1 (2505j)5 j5(45500