1、第第2章章 电路的分析方法电路的分析方法URRRU2111 URRRU2122 IRRRI2121 IRRRI2112 21111 RRR ROY-ROCBADCADBbcRaRcRbabCRaRcRba)/()/()/(bcabcacabaabbccbbacaabbaRRRRRRRRRRRRRRR CbCRaRcRbabaccbbacaaaccbbabccccbbaabRRRRRRRRRRRRRRRRRRRRRRRRa cabcabbccaccabcababbcbcabcabcaabaRRRRRRRRRRRRRRRRRR Y Y a等效变换等效变换bcRaRcRbbcRaRcRba例例1：1
2、2由图：由图：R12=2.68 12CD12 284484cabcabcaaba RRRRRR 184444b R 284448c R 52)1(5)24()1(5)24(RA A 2.15121524151 I0SREI 注意事项：注意事项：解解:+abU2 5V(a)+abU5V(c)+a+-2V5VU+-b2(c)+(b)aU 5A2 3 b+(a)a+5V3 2 U+a5AbU3(b)+A1A22228 I例例3：解：解：2 +-+-6V4VI2A 3 4 6 1 2A3 6 2AI4 2 1 1AI4 2 1 1A2 4AA2A3122 II4 2 1 1A2 4A1 I4 2 1A
3、2 8V+-I4 1 1A4 2AI2 1 3A作业:P76 2.1 (C)(D)2.2(A)2.7Thanks!当不需求当不需求a、c和和b、d间的电流时，间的电流时，(a、c)(b、d)可分别看成一个结点。可分别看成一个结点。支路数支路数b=4，且恒流，且恒流源支路的电流已知。源支路的电流已知。I1=2A，I2=3A，I3=6A 例例3：试求各支路电流试求各支路电流。对结点对结点 a：I1+I2 I3=7对回路对回路1：12I1 6I2=42对回路对回路2：6I2 +UX=0baI2I342V+I112 6 7A3 cd123+UX对回路对回路3：UX+3I3=0结点电压方程的推导：结点电
4、压方程的推导：设：设：Vb=0 V 结点电压为结点电压为 U，参，参考方向从考方向从 a 指向指向 b。111RIEU 因因为为111RUEI 所所以以2.应用欧姆定律求各支路电流应用欧姆定律求各支路电流：111RUEI 222RUEI 33RUI 1.用用KCL对结点对结点 a 列方程：列方程：I1 I2+IS I3=0E1+I1R1U+baE2+I2ISI3E1+I1R1R2R3+U3211RUIRUERUE S23212211111RRRIREREUS RIREUS1 RIREU1Sab V18V316112171242 A2 A1218421242ab1 UIA3 A618 6 ab2
5、 UIA6 3183ab3 UI212S1S2211ab11RRIIREREU V24V312127330250 1ab11RUEI A13A22450 A18A324302ab22 RUEI1A11RVUIS2A2RVI 3AB3RVVI4B4RVI 5B25RVUISR1作业:P77 2.9 2.11 2.15Thanks!2121RREII SIRRRI2121 S21221111IRRRRREIII SIRRRI2112 S21121IRRRRRE 22112S1RIRIEIII S212211 IRRRRREI S211212 IRRRRREI 12112112111211)(RIR
6、IRIIRIP A1A5510322 RREIV5V5122S RIUA5.0A5.0A1 222 III所所以以A5.01555S3232 IRRRIV5.2V55.022S RIUV5.72.5V5VSSS UUUA5.2A4420402121 RREEI 221210RRRRR，所以所以A2A13230303 RREIA2.1A5512211 RREIA8.0A51012432 RREIR0abR3R4R1R2 8.5434321210RRRRRRRRR，所以所以A126.0A108.52G0G RREIA07.2A8.512 REI A38.1A07.2510103131 IRRRI A035.12142 IIIA126.0 A345.0108.58.5 SG00G IRRRI 作业:P77 2.21 2.23 2.24Thanks!
